Cabaletta Bio, Inc. 10-K

Item 9A. Controls and Procedures. Evaluation of Disclosure Controls and Procedures The Company has established disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act) designed to ensure that information required to be disclosed in the reports that the Company files or submits under the Securities Exchange Act of 1934, as amended, or Exchange Act, is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms and is accumulated and communicated to management, including the principal executive officer (our Chief Executive Officer) and principal financial officer (our Chief Financial Officer), to allow timely decisions regarding required disclosure. In addition, the design of disclosure controls and procedures must reflect the fact that there are resource constraints and that management is required to apply judgment in evaluating the benefits of possible controls and procedures relative to their costs. Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated, as of December 31, 2024, the effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act). Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Our disclosure controls and procedures have been designed to provide reasonable assurance of achieving their objectives. Based on that evaluation, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act) were effective at the reasonable assurance level as of December 31, 2024. Management’s Annual Report on Internal Control Over Financial Reporting Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Internal control over financial reporting is a process designed to provide reasonable assurance of the reliability of financial reporting and of the preparation of consolidated financial statements for external reporting purposes, in accordance with U.S. generally accepted accounting principles. Internal control over financial reporting includes policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect transactions and disposition of assets; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of consolidated financial statements in accordance with U.S. generally accepted accounting principles, and that receipts and expenditures are being made only in accordance with the authorization of its management and directors; and (3) provide reasonable assurance regarding the prevention or timely detection of unauthorized acquisition, use, or disposition of our assets that could have a material effect on its consolidated financial statements. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of the effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies and procedures included in such controls may deteriorate. Our management has assessed the effectiveness of our internal control over financial reporting as of December 31, 2024. In making this assessment, management used the criteria established by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in Internal Control - Integrated Framework (2013). These criteria are in the areas of control environment, risk assessment, control activities, information and communication, and monitoring. Management’s assessment included extensive documentation, evaluating and testing the design and operating effectiveness of its internal controls over financial reporting. Based on management’s processes and assessment, as described above, management has concluded that, as of December 31, 2024, our internal control over financial reporting was effective. Attestation Report of the Registered Public Accounting Firm As a non-accelerated filer, we are not required to provide an attestation report of our independent registered public accounting firm on the effectiveness of our internal control over financial reporting. 111 Changes in Internal Control over Financial Reporting There was no change in our internal control over financial reporting (as defined in Rule 13a-15(f) of the Exchange Act) that occurred during the fiscal quarter ended December 31, 2024 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting. Item 9B. Other Information. Rule 10b5-1 Trading Plans During the fiscal quarter ended on December 31, 2024, none of our directors and officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted , modified or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as those terms are defined in Item 408(a) of Regulation S-K, except as described in the table below: Name and Title Action Action Date Duration of Trading Arrangements (1) Rule 10b5-1 Trading Arrangement? (Y/N)* Aggregate Number of Securities Subject to Trading Arrangement Steven Nichtberger Chief Executive Officer Terminate (2) October 18, 2024 July 8, 2024 - July 31, 2025 Y Up to 350,000 shares to be sold Steven Nichtberger Chief Executive Officer Adopt (2) October 18, 2024 February 16, 2025 – July 27, 2026 Y Up to 350,000 shares to be sold Gwendolyn Binder President of Science and Technology Terminate November 21, 2024 February 20, 2024 – February 21, 2025 Y Up to 100,756 shares to be sold Gwendolyn Binder President of Science and Technology Adopt December 18, 2024 March 27, 2025 to December 12, 2025 Y Up to 100,756 shares to be sold * Denotes whether the trading plan is intended, when adopted, to satisfy the affirmative defense of Rule 10b5-1(c). (1) Except as indicated by footnote, each trading arrangement permitted or permits transactions through and including the earlier to occur of (a) the completion of all purchases or sales or (b) the date listed in the table. (2) Represents the modification, as described in Rule 10b5-1(c)(1)(iv) under the Exchange Act, of a written trading arrangement adopted on November 9, 2023 that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections. Not applicable. 112 PART III Item 10. Directors, Executive Off icers and Corporate Governance. The following table sets forth information about our directors and executive officers as of March 27, 2025. Name Positions and Offices Held with Cabaletta Officer/Director Since Class and Year in Which Term Will Expire Age Executive Officers Steven Nichtberger, M.D. Chief Executive Officer, President, Chairman of the Board of Directors and Director 2017 Class III—2025 63 Gwendolyn K. Binder, Ph.D. President, Science and Technology 2019 — 50 Anup Marda, MBA Chief Financial Officer 2019 — 47 David J. Chang, M.D., M.P.H. Chief Medical Officer 2019 — 62 Michael Gerard, J.D. General Counsel and Secretary 2021 — 45 Arun Das, M.D. Chief Business Officer 2022 — 35 Non-Employee Directors Mark Simon, MBA (1)(2)(3) Director 2018 Class III—2025 63 Scott Brun, M.D. (1)(3) Director 2021 Class I—2026 57 Shawn Tomasello, MBA (2) Director 2023 Class I—2026 66 Catherine Bollard, MBChB, M.D. (3) Director 2019 Class II—2027 57 Richard Henriques, MBA (1)(2) Director 2019 Class II—2027 69 (1) Member of the Audit Committee. (2) Member of the Compensation Committee. (3) Member of the Nominating and Corporate Governance Committee. Executive Officers Steven Nichtberger, M.D. Dr. Nichtberger has served as our Chief Executive Officer, President and Chairman of our board of directors since our founding in 2017. He is also a Professor of Professional Practice in the Vagelos LSM program and adjunct professor at The Wharton School of the University of Pennsylvania in addition to being a member of the board of directors of the BioAdvance Greenhouse Fund. Previously, Dr. Nichtberger served as president, chief executive officer, and a member of the board of directors of Tengion, Inc. from 2004 to 2011. In 2008, his leadership was recognized nationally with the National Ernst & Young Entrepreneur of the Year Award for emerging companies. Earlier in his career, Dr. Nichtberger served as the head of global marketing for Merck and in various commercial operating roles at the company from 1995 to 2003. He has previously served as a member of the boards of directors of the Alliance for Regenerative Medicine (as a founding member), Pennsylvania Bio (including as chairman), and Biotechnology Industry Organization. From 2008 to 2019, he was a member of the board of overseers for the School of Arts & Sciences at the University of Pennsylvania. Dr. Nichtberger received his M.D. from the State University of New York at Buffalo, his B.S. from The Wharton School at the University of Pennsylvania and his B.A. from the University of Pennsylvania. He completed internship, residency and fellowship in the Department of Medicine and the Division of Cardiology of the Mount Sinai Medical Center in New York. We believe Dr. Nichtberger is qualified to serve as a member and Chairman of our board of directors because of his scientific and medical background as well as his corporate leadership experience. Gwendolyn K. Binder, Ph.D. Dr. Binder joined our company in February 2019 as our Executive Vice President, Science and Technology and was appointed President, Science and Technology in January 2022. Dr. Binder is an R&D executive with specialized expertise in the discovery and early clinical development and optimization of engineered T cell therapies. Prior to joining Cabaletta, Dr. Binder was the Chief Technology Officer of Adaptimmune Therapeutics Plc from March 2016 to January 2019, where she ultimately led the research team focusing on understanding mechanisms of tumor response and resistance and translating this understanding to next generation products and clinical study designs. In prior roles, from March 2011 to February 2016, she established and led the translational research group, in addition to the manufacturing and quality teams including oversight of the buildout of an in-house manufacturing facility. Earlier in her career, Dr. Binder served as Director of Operations for the Translational Research Program at the University of Pennsylvania, where she where she progressed multiple investigational new drug submissions for novel engineered T-cell therapies in HIV and oncology, including the CD19 CAR IND acquired by Novartis (now Kymriah), the first human gene editing IND, and three TCR engineered T cell therapy studies in oncology and HIV. Prior to that, she served as the 113 Director of Scientific Affairs at VIRxSYS Corporation in Gaithersburg Maryland where she supported the development of the first clinical lentiviral vector used in humans, for the application of engineered T cell therapy for HIV. In addition, Dr. Binder has served on the Board of Directors of Instil Bio (Nasdaq: TIL), a clinical-stage biopharmaceutical company focused on developing a pipeline of novel therapies including a lead PD-L1xVEGF bispecific antibody for solid tumors, since July 2020, and as a member of the Scientific Advisory Board for Immatics, which is a publicly traded company developing engineered T cell immunotherapy for cancer, since July 2020. Dr. Binder studied viral immunology and translational research at the Johns Hopkins University in Baltimore, Maryland where she earned a Ph.D. in Cellular and Molecular Medicine in 2002. She has authored over 30 publications in the field, including top international journals such as “Science”, and “Nature Medicine”. She is a recognized leader in the biotechnology sector for the translational and clinical advancement of novel T cell therapies for patients with serious diseases. Anup Marda, MBA. Mr. Marda joined our company in January 2019 as our Chief Financial Officer. From April 2001 to January 2019, Mr. Marda held positions at Bristol-Myers Squibb, including, most recently, as Vice President, Head of Global Corporate Financial Planning & Analysis, and previously as Head of Finance, R&D Operations and Head of Finance, R&D Portfolio Management and Global Medical from 2014 to 2018. Prior to this, Mr. Marda held the role of Executive Director, U.S. Pharmaceuticals from 2012 to 2014 and Assistant Treasurer, Capital Markets from 2008 to 2012. Mr. Marda received his MBA from the Krannert School of Business of Purdue University and his B.Tech in Chemical Engineering from the Indian Institute of Technology Bombay. David J. Chang, M.D., M.P.H. Dr. Chang joined our company in June 2019 as our Chief Medical Officer. From June 2015 to May 2019, he was Senior Vice President and Head, Inflammation, Autoimmunity & Neuroscience, or IA&NS, Global Medicines Development at AstraZeneca Pharmaceuticals LP, where he oversaw development projects of both biologics and small molecules in a variety of indications and led the late-stage clinical development organization for IA&NS. From October 2007 to June 2015, Dr. Chang served in various positions at GlaxoSmithKline plc, including VP and Head, Immuno-Inflammation, Clinical Development. While at AstraZeneca and GlaxoSmithKline, he provided leadership in driving the clinical development and registration of the only two products approved for systemic lupus erythematosus in the US in over 60 years. He received his M.D. from New York University School of Medicine, his M.P.H. from Emory University and his B.S. from Yale University. Dr. Chang completed his internship and residency in internal medicine at the New York Hospital—Cornell University Medical Center and fellowship in rheumatology at the Hospital for Special Surgery—Cornell University Medical Center. Michael Gerard, J.D. Mr. Gerard joined our company in September 2021 as our General Counsel and Secretary. Prior to joining Cabaletta, Mr. Gerard served as Associate General Counsel of Spark Therapeutics, Inc., or Spark, from September 2020 to August 2021. Prior to Spark, Mr. Gerard served in various legal roles at Sandoz, Inc., a division of the Novartis Group, beginning in 2013, with the most recent role being Executive Director, Associate General Counsel, Business Development and Licensing, Strategy and Portfolio. Earlier in his career, Mr. Gerard served as Assistant General Counsel at Aramark and as a litigator at the law firms of Morrison & Foerster, LLP and K&L Gates, LLP in New York. Mr. Gerard received a B.A. in Political Science from the University of Michigan, Ann Arbor and a J.D. from Cornell Law School. Arun Das, M.D. Dr. Das joined our company in July 2019 after serving as a consultant to the company since 2017, and served in several roles, most recently Executive Director of New Product Planning and Business Development, prior to being appointed Chief Business Officer in January 2022. He is also a Lecturer in the Health Care Management Department at the Wharton School of the University of Pennsylvania. Prior to joining Cabaletta, Dr. Das was a resident physician in General Pediatrics at the Children’s Hospital of Philadelphia from June 2018 to June 2019. Previously, he was an investment banking analyst in the healthcare group at Goldman Sachs from 2010 to 2012. In addition, Dr. Das has spent multiple years consulting in business development and operations for several start-ups in the biotechnology space. Dr. Das received his M.D. from Johns Hopkins University School of Medicine and a B.A. and B.S. dual degree from the University of Pennsylvania. Non-Employee Directors Mark Simon, MBA . Mr. Simon joined our board of directors in October 2018. He is a Strategic Advisor since 2020 to the Founder and CEO of Sun Pharmaceutical Industries Ltd., which is the largest pharmaceutical company in India, and a board observer of Sun Pharma Advanced Research Company Ltd., both public companies in India, where Mr. Simon is focused on accelerating their innovation initiatives. He is also a consultant to Stifel Nicolaus & Company (NYSE: SF) and co-founder of Torreya Partners, LLC, a global investment banking firm serving companies in the life sciences industry that Stifel acquired in 2023. Prior to co-founding Torreya, Mr. Simon was a managing director and head of life sciences investment banking at Citigroup from 2002 to 2005 where he covered global pharmaceutical companies with a focus on large-capitalization players in the U.S., Europe and Japan. Prior to Citigroup, Mr. Simon served as a Managing Director at Robertson Stephens in San Francisco and New York where he was responsible for covering the biotechnology investment banking sector. During his tenure overseeing the group, he was involved in raising 45% of all biotechnology dollars raised in the U.S. from 1999-2001. Prior to joining the investment banking group, Mr. 114 Simon was a senior biotechnology research analyst at Robertson Stephens, and was named a Wall Street All-Star Analyst for three years in a row. He began his career at Kidder Peabody as a biotechnology research associate in 1984 and participated in the IPO of Genzyme and the early financings of companies such as Amgen. Mr. Simon currently serves on the boards of directors of several disease advocacy and philanthropic foundations in the oncology, CNS/neuroscience and metabolic areas. He previously served on the board of directors of Portage Biotech Inc. (Nasdaq: PRTG) until April 2024. Mr. Simon received his MBA from Harvard Business School and his B.A. from Columbia College. We believe that Mr. Simon is qualified to serve on our board of directors because of his extensive experience of over 35 years in the life sciences industry and biotechnology and specialty pharmaceutical transactions. Scott Brun, M.D. Dr. Brun joined our board of directors in June 2021. Dr. Brun is currently President at Gold Mast Consulting, LLC, an advisory firm he founded in 2019 to provide technical advice and strategic guidance related to biopharmaceutical research and development, pipeline portfolio management, commercialization of new therapeutics and strategic communications related to R&D activities. Dr. Brun serves as a Venture Partner at Abingworth LLP and a Senior Medical Advisor to Launch Therapeutics. Prior to his current roles, Dr. Brun had two decades of experience in various leadership roles at AbbVie, Inc., including 15 years at the predecessor company, Abbott Laboratories. The majority of his career has been focused on leading teams and clinical development organizations across a broad variety of therapeutic areas including autoimmune, neurologic, and renal among others. He was most recently Corporate Vice President of Scientific Affairs and Head of AbbVie Ventures, a corporate venture fund responsible for investment opportunities within AbbVie’s R&D therapeutic areas as well as technology platforms of interest from 2016 to 2019. Previously, Dr. Brun served as Corporate Vice President and Head of Pharmaceutical Development at AbbVie from 2013 to 2016. During his tenure at AbbVie, Dr. Brun oversaw a global organization with responsibilities for AbbVie’s entire portfolio of early and late-stage clinical pre-registration pipeline compounds as well as marketed compounds within oncology, neurology, immunology, renal, infectious disease, and women’s and men’s health therapeutic areas. Prior to joining AbbVie, Dr. Brun spent over 15 years at Abbott Laboratories, where he held positions of increasing leadership responsibility in drug development within the R&D organization. Dr. Brun is a member of the boards of directors of Axial Biotherapeutics, Inc. and Trishula Therapeutics, Inc., both private, clinical-stage biopharmaceutical companies, Jasper Therapeutics, Inc. (Nasdaq: JSPR) a biotechnology company focused on targeting mast cells and stem cells to treat chronic diseases and Forte Biosciences, Inc. (Nasdaq: FBRX) a preclinical-stage company focused on autoimmune diseases. Previously, Dr. Brun served as a Senior Advisor to the business development team at Horizon Therapeutics plc (Nasdaq: HZNP) from 2020 to 2023. Dr. Brun received his B.S. in Biochemistry from the University of Illinois at Urbana-Champaign and earned his M.D. from the Johns Hopkins University School of Medicine. He completed his residency in ophthalmology at the Massachusetts Eye and Ear Infirmary, Harvard Medical School. We believe Dr. Brun is qualified to serve as a member of our board of directors because of his scientific background and significant experience in clinical and research efforts. Shawn Tomasello, MBA . Ms. Tomasello joined our Board of Directors in July 2023. She is currently Chief Executive Officer at CoRegen, Inc., a private company. Prior to her current role, Ms. Tomasello served as the Chief Commercial Officer of Kite Pharma, where she oversaw the global commercialization of Yescarta, from 2015 to 2018 including through its acquisition by Gilead for $11.9 billion in October 2017. She was previously Chief Commercial Officer at Pharmacyclics, where she led commercial and medical affairs activities for Imbruvica®, a first-in-class treatment for hematologic malignancies, from August 2014 until its acquisition by AbbVie for $21.0 billion in August 2015. Prior to Pharmacyclics, Ms. Tomasello served in leading commercial roles with multiple major pharmaceutical companies, including Celgene as President of the Americas Hematology and Oncology, where she led the company through five successful product launches encompassing 11 indications and played a critical role in acquisitions. At Genentech for 14 years prior, Ms. Tomasello was the National Director of Hematology for Rituxan. She currently serves on the board of directors of AlloVir, Inc. (Nasdaq: ALVR) since March 2022, 4D Molecular Therapeutics Inc. (Nasdaq: FDMT) since November 2020 and Centrexion Therapeutics Corp., a private, clinical-stage biopharmaceutical company, since 2017. She previously served as a board member of TCR2 Therapeutics Inc. (Nasdaq: TCRR) until June 2023, Urogen Pharma Ltd (Nasdaq: URGN) until 2022, Mesoblast, Ltd. (Nasdaq: MESO) until August 2022, Clementia Pharmaceuticals, Diplomat Pharmacy, Inc. until 2020, Abeona Therapeutics (Nasdaq: ABEO) until 2020, Principia Biopharma until 2020, and Gamida Cell Ltd. (Nasdaq: GMDA) until 2024, as well as several private boards. On such boards, she at various times has served and serves on the Compensation, Nominating and Corporate Governance, Compliance, and Transaction committees. Ms. Tomasello received her B.S. in Marketing from the University of Cincinnati and her M.B.A. from Murray State University in Kentucky. We believe Ms. Tomasello is qualified to serve as a member of our Board of Directors because of her experience serving in various commercial roles in the life sciences industry. Catherine Bollard, MBChB, M.D. Dr. Bollard joined our board of directors in April 2019. She currently serves as Senior Vice President and Chief Research Officer and Director of the Center for Cancer and Immunology Research at the Children’s National Research Institute (CNRI). She is also a faculty member of the Division of the Blood and Marrow Transplantation at CNH. Since 2013, Dr. Bollard has served as a tenured Professor of Pediatrics and Microbiology, Immunology and Tropical Medicine at the George Washington University and is the Associate Center Director (ACD) for Translational Research and Innovation within the George Washington Cancer Center. Prior to her move in 2013, Dr. Bollard was Professor of Pediatrics, Medicine and 115 Immunology at Baylor College of Medicine. She is a past president of the International Society for Cell Therapy (ISCT), and she served on the Cellular, Tissues and Gene Therapy Advisory Committee of the FDA until 2019. Dr. Bollard chaired the Non-Hodgkin’s Lymphoma Committee of the Children’s Oncology Group from 2012 to 2020 and in 2021 became the President of the Foundation for the Accreditation of Cellular Therapy (FACT). Dr. Bollard was the scientific co-founder of Catamaran Bio, a company developing novel, off-the-shelf chimeric antigen receptor (CAR)-NK cell therapies designed to treat a broad range of cancers and served on its Scientific Advisory Board until 2024. Dr. Bollard was previously on the board of directors and subsequently the Scientific Advisory Board of Mana Therapeutics. She currently serves on the SAB of Minovia Tx Ltd and serves as Chair of the DSMB for SOBI. Bollard also serves on the board of directors for Alliance for Regenerative Medicine and a nonprofit organization she co-founded called Access4Kids. Dr. Bollard received her medical degree (MBChB) and her doctor of medicine (MD) from the University of Otago Medical School in New Zealand. We believe Dr. Bollard is qualified to serve as a member of our board of directors because of her scientific background and significant experience in clinical and translational research efforts. Richard Henriques, MBA. Mr. Henriques joined our board of directors in February 2019. Since 2015, he has been a senior fellow at the Center for High Impact Philanthropy at the University of Pennsylvania, with a focus on impact investing. From 2010 to 2014, Mr. Henriques was the Chief Financial Officer of the Bill & Melinda Gates Foundation, where he was responsible for finance and accounting, financial planning and analysis, strategic planning, measurement and evaluation, program related investments and information technology. From 1981 to 2008, Mr. Henriques held positions at Merck & Co., Inc., including as Senior Vice President of Finance for Global Human Health, Vice President and Corporate Controller, and Principal Accounting Officer. Mr. Henriques serves on the boards of directors or trustees of the Bucks County Playhouse, International Vaccine Institute, Heritage Conservancy, Delaware Canal 21, Fisherman’s Mark and The Franklin Institute. Mr. Henriques served on the board of directors of Arbutus Biopharma Corporation (Nasdaq: ABUS) from December 2014 to February 2025. Mr. Henriques received his MBA from the Wharton School of the University of Pennsylvania and a BA from the University of Pennsylvania. We believe that Mr. Henriques is qualified to serve as a member of our board of directors because of his extensive corporate leadership experience and expertise in finance and investment management. Family Relationships and Legal Proceedings There are no family relationships between or among any of our directors or executive officers. Our executive officers are appointed by, and serve at the discretion of, our board of directors. The principal occupation and employment during the past five years of each of our directors was carried on, in each case except as specifically identified above, with a corporation or organization that is not a parent, subsidiary or other affiliate of us. There is no arrangement or understanding between any of our directors and any other person or persons pursuant to which he or she is to be selected as a director. There are no material legal proceedings to which any of our directors, officers or affiliate, any owner of record or beneficially of more than five percent of any class of our voting securities, or any associate of any such director, officer, affiliate, or security holder is a party adverse to us or any of our subsidiaries or in which any such person has a material interest adverse to us or our subsidiary. Board Committees Our board of directors has established an audit committee, a compensation committee, and a nominating and corporate governance committee. Each of the audit committee, compensation committee, and nominating and corporate governance committee operates under a charter that satisfies the applicable standards of the SEC and Nasdaq. Our board of directors has also established a science and technology committee, an advisory committee of the board of directors which operates under a charter duly adopted by the board of directors. Each such committee reviews its respective charter at least annually. A current copy of the charter for each of the audit committee, compensation committee, nominating and corporate governance committee and science and technology committee is posted on the corporate governance section of our website, www.cabalettabio.com/investors/corporate-governance/governance-documents . From time to time, our board of directors may establish certain committees for scientific, business or other matters. Audit Committee Scott Brun, M.D., Richard Henriques, MBA and Mark Simon, MBA serve on the audit committee, which is chaired by Richard Henriques, MBA. Our board of directors has determined that each member of the audit committee is “independent” for audit committee purposes as that term is defined in the rules of the SEC and the applicable Nasdaq rules, and each has sufficient knowledge in financial and auditing matters to serve on the audit committee. Our board of directors has designated Mr. Henriques as an “audit 116 committee financial expert,” as defined under the applicable rules of the SEC. During the fiscal year ended December 31, 2024, the audit committee met seven times. The audit committee’s responsibilities include: • appointing, approving the compensation of, and assessing the independence of our independent registered public accounting firm; • pre-approving auditing and permissible non-audit services, and the terms of such services, to be provided by our independent registered public accounting firm; • reviewing the overall audit plan with our independent registered public accounting firm and members of management responsible for preparing our financial statements; • reviewing and discussing with management and our independent registered public accounting firm our annual and quarterly financial statements and related disclosures as well as critical accounting policies and practices used by us; • coordinating the oversight and reviewing the adequacy of our internal control over financial reporting; • establishing policies and procedures for the receipt and retention of accounting-related complaints and concerns; • recommending based upon the audit committee’s review and discussions with management and our independent registered public accounting firm whether our audited financial statements and our related disclosures under the “Management’s Discussion and Analysis” section shall be included in our 2024 Annual Report; • monitoring the integrity of our financial statements and our compliance with legal and regulatory requirements as they relate to our financial statements and accounting matters; • preparing the audit committee report required by SEC rules to be included in our annual proxy statement; • reviewing all related person transactions for potential conflict of interest situations and approving all such transactions; • reviewing quarterly earnings releases; and • discussing the Company’s risk assessment and management guidelines, including the Company’s major financial risk exposures, cybersecurity risks and the steps that the Company’s management has taken to monitor and control such exposures and risks. All audit and non-audit services, other than de minimis non-audit services, to be provided to us by our independent registered public accounting firm must be approved in advance by our audit committee. Compensation Committee Richard Henriques, MBA, Mark Simon, MBA and Shawn Tomasello, MBA serve on the compensation committee, which is chaired by Mark Simon, MBA. Our board of directors has determined that each member of the compensation committee is “independent” as defined in the applicable Nasdaq rules. During the fiscal year ended December 31, 2024, the compensation committee met four times. The compensation committee’s responsibilities include: • annually reviewing and recommending to the board of directors corporate goals and objectives relevant to the compensation of our chief executive officer; • evaluating the performance of our chief executive officer in light of such corporate goals and objectives and based on such evaluation (i) recommending to the board of directors the cash compensation of our chief executive officer and (ii) reviewing and approving grants and awards to our chief executive officer under equity-based plans; • reviewing and approving the compensation of our other executive officers; • reviewing and establishing our overall management compensation, philosophy, and policy; • overseeing and administering our compensation and similar plans; • evaluating and assessing potential and current compensation advisors in accordance with the independence standards identified in the applicable Nasdaq rules; • reviewing and making recommendations to our board of directors about our policies and procedures for the grant of equity-based awards; 117 • preparing the compensation committee report required by SEC rules, if and when required, to be included in our annual proxy statement; • reviewing and discussing annually with management our “Compensation Discussion and Analysis,” if and when required, to be included in our annual proxy statement; and • reviewing and approving the retention or termination of any consulting firm or outside advisor to assist in the evaluation of compensation matters. Nominating and Corporate Governance Committee Catherine Bollard, MBChB, M.D., Scott Brun, M.D., and Mark Simon, MBA, serve on the nominating and corporate governance committee, which is chaired by Scott Brun, M.D. Our board of directors has determined that each member of the nominating and corporate governance committee is “independent” as defined in the applicable Nasdaq rules. During the fiscal year ended December 31, 2024, the nominating and corporate governance committee met two times. The nominating and corporate governance committee’s responsibilities include: • developing and recommending to the board of directors criteria for board and committee membership; • establishing procedures for identifying and evaluating board of director candidates, including nominees recommended by stockholders; • reviewing the composition of the board of directors to ensure that it is composed of members containing the appropriate skills and expertise to advise us; • identifying individuals qualified to become members of the board of directors; • recommending to the board of directors the persons to be nominated for election as directors and to each of the board’s committees; • reviewing and discussing with the board of directors corporate succession plans for our chief executive officer and other key officers; • developing and recommending to the board of directors a code of business conduct and ethics and a set of corporate governance guidelines; and • overseeing the evaluation of our board of directors. The nominating and corporate governance committee considers candidates for board of directors membership suggested by its members and the chief executive officer. Additionally, in selecting nominees for directors, the nominating and corporate governance committee will review candidates recommended by stockholders in the same manner and using the same general criteria as candidates recruited by the committee and/or recommended by our board of directors. Any stockholder who wishes to recommend a candidate for consideration by the committee as a nominee for director should follow the procedures described in our proxy statement under the heading “Stockholder Proposals.” The nominating and corporate governance committee will also consider whether to nominate any person proposed by a stockholder in accordance with the provisions of our bylaws relating to stockholder nominations as described in our proxy statement under the heading “Stockholder Proposals.” Identifying and Evaluating Director Nominees. Our board of directors is responsible for filling vacancies on our board of directors and for nominating candidates for election by our stockholders each year in the class of directors whose term expires at the relevant annual meeting. The board of directors delegates the selection and nomination process to the nominating and corporate governance committee, with the expectation that other members of the board of directors, and of management, will be requested to take part in the process as appropriate. Generally, the nominating and corporate governance committee identifies candidates for director nominees in consultation with management, through the recommendations submitted by stockholders or through such other methods as the nominating and corporate governance committee deems to be helpful to identify candidates. Once candidates have been identified, the nominating and corporate governance committee confirms that the candidates meet all of the minimum qualifications for director nominees established by the nominating and corporate governance committee. The nominating and corporate governance committee may gather information about the candidates through interviews, detailed questionnaires, comprehensive background checks or any other means that the nominating and corporate governance committee deems to be appropriate in the evaluation process. The nominating and corporate governance committee then meets as a group to discuss and evaluate the qualities and skills of each candidate, both 118 on an individual basis and taking into account the overall composition and needs of our board of directors. Based on the results of the evaluation process, the nominating and corporate governance committee recommends candidates for the board of directors’ approval to fill a vacancy or as director nominees for election to the board of directors by our stockholders each year in the class of directors whose term expires at the relevant annual meeting. Science and Technology Committee Catherine Bollard, MBChB, M.D., Scott Brun, M.D., and Shawn Tomasello, MBA, serve on the science and technology committee, which is chaired by Catherine Bollard, MBChB, M.D. The science and technology committee supports Board oversight of the Company’s research and development, manufacturing and supply activities, by providing a forum for review of strategic considerations and issues in such areas, as well as to evaluate relevant emerging technology and advances in the field. The science and technology committee was formed in July 2023 and held four meetings in during the fiscal year ended December 31, 2024. Code of Business Conduct and Ethics We have adopted a written code of business conduct and ethics that applies to our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A current copy of the code is posted on the corporate governance section of our website, which is located at www.cabalettabio.com/investors/corporate-governance/governance-documents . If we make any substantive amendments to, or grant any waivers from, the code of business conduct and ethics for any officer or director, we will disclose the nature of such amendment or waiver on our website or in a current report on Form 8-K. Insider Trading Policies and Procedures We have adopted an insider trading policy that governs the purchase, sale, and/or other transactions of our securities by our directors, officers, employees and designated consultants that we believe is reasonably designed to promote compliance with applicable insider trading laws, rules and regulations, and listing standards applicable to us. A copy of our insider trading policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K for the fiscal year ended December 31, 2024. In addition, with regard to trading in our own securities, it is our policy to comply with the federal securities laws and the applicable exchange listing requirements. Our insider trading policy prohibits our directors, officers, employees and certain designated consultants, and their affiliated persons, from trading in company securities while in possession of material nonpublic information about our company. The policy also prohibits tipping (i.e., disclosing material nonpublic information about our company to others who may trade of the basis of that information). Under our insider trading policy, designated insiders may only trade in company securities at a time when they do not possess material nonpublic information about our company. We also require our directors, officers and certain other employees to receive approval before trading in company securities. Our insider trading policy also expressly prohibits short sales; purchases or sales of puts, calls, or other derivative securities or hedging transactions; using company securities as collateral in a margin account; or pledging company securities as collateral for a loan. Any waiver of the provisions of this policy requires the approval of our Audit Committee. To date, no such requests have been made or approved. We have also adopted an additional policy that governs adoption, modification and termination of written securities trading plans, known as Rule 10b5-1 plans, by our directors, executive officers and certain other persons. Our policy provides that all Rule 10b5-1 plans must comply with SEC rules applicable to the Rule 10b5-1 safe harbor and imposes additional requirements and limitations. 119 Item 11. Executiv e Compensation. Our named executive officers for the year ended December 31, 2024 are: • Steven Nichtberger, M.D., our President and Chief Executive Officer; • Gwendolyn Binder, Ph.D., our President, Science and Technology; and • David J. Chang, M.D., M.P.H., our Chief Medical Officer. 2024 Summary Compensation Table The following table presents the compensation awarded to, earned by or paid to each of our named executive officers for the years indicated. Dr. Nichtberger also serves as a member of our board of directors but does not receive any additional compensation for his service as a director. Year Salary ($) Option Awards ($)(1) Non-Equity Incentive Plan Compensation ($)(2) All Other Compensation ($)(3) Total ($) Steven Nichtberger, M.D. 2024 646,328 7,008,417 428,157 14,045 8,096,947 President and Chief Executive Officer 2023 597,417 3,784,529 412,288 14,045 4,808,279 Gwendolyn K. Binder, Ph.D. 2024 529,687 2,581,003 246,869 — 3,357,559 President, Science and Technology 2023 477,417 1,618,263 245,203 — 2,340,883 David J. Chang, M.D., M.P.H. 2024 496,833 2,581,003 268,290 — 3,346,126 Chief Medical Officer 2023 476,910 1,379,202 244,940 — 2,101,052 (1) Amounts reflect the grant date fair value of option awards granted in 2024 and 2023 in accordance with the Financial Accounting Standards Board’s Accounting Standards Codification Topic 718, or ASC 718. Such grant date fair value does not take into account any estimated forfeitures related to service-vesting conditions. For information regarding assumptions underlying the valuation of equity awards, see Note 10 to our financial statements for the year ended December 31, 2024. These amounts do not correspond to the actual value that may be recognized by the named executive officers upon vesting of applicable awards. (2) The amounts represent bonuses earned in 2024 and 2023 and paid in 2025 and 2024, respectively, pursuant to the Company’s cash incentive plan based on the factors described under “Non-Equity Incentive Plan Compensation” below. (3) Amount includes reimbursements for life insurance premiums. Narrative to 2024 Summary Compensation Table Our board of directors and compensation committee review compensation annually for our chief executive officer and his direct reports. In setting executive base salaries and bonuses, and granting equity incentive awards, our board of directors considers compensation for comparable positions in the market, the historical compensation levels of our executives, individual performance as compared to our expectations and objectives, our desire to motivate our employees to achieve short-and long-term results that are in the best interests of our stockholders, and a long-term commitment to our company. We target a general competitive position, based on independent third-party benchmark analytics to inform the mix of compensation of base salary, bonus or long-term incentives. Our board of directors has historically determined our executives’ compensation. Our compensation committee typically reviews and discusses management’s proposed compensation with the chief executive officer for all of his direct reports. Based on those discussions and its discretion, taking into account the factors noted above, the compensation committee determines the compensation for each executive officer other than the chief executive officer. Our board of directors discusses the compensation committee’s recommendations and ultimately approves the compensation of our chief executive officer without the chief executive officer and chief financial officer present. In 2024, the compensation committee continued to retain the services of Radford, an AON Hewitt company, as its external compensation consultant and the board of directors and the compensation committee considered Radford’s input on certain compensation matters as they deemed appropriate. Annual base salary Each named executive officer’s base salary is a fixed component of annual compensation for performing specific duties and functions, and has been established by our board of directors taking into account each individual’s role, responsibilities, skills, and 120 experience. Base salaries for our named executive officers are reviewed annually by our compensation committee, typically in connection with our annual performance review process, and adjusted from time to time, based on the recommendation of the compensation committee, to realign salaries with market levels after taking into account individual responsibilities, performance, and experience. The base salary of each named executive officer in 2024 is noted below: Name 2024 Base Salary through February 29, 2024 Base Salary Effective March 1, 2024 Steven Nichtberger, M.D. 602,200 638,300 Gwendolyn K. Binder, Ph.D. 480,500 500,200 David J. Chang, M.D., M.P.H. 480,000 500,200 Non-Equity Incentive Plan Compensation Annual cash awards are determined based on company performance, which is assessed based on predetermined annual objectives, and on individual performance. When determining the individual component of our annual incentive awards, the compensation committee considers each executive’s contributions to the company’s strategic achievements and financial and operational performance. In addition, the compensation committee considers how each executive demonstrates Cabaletta behaviors. Each of our named executive officers was eligible to receive a bonus with respect to 2024 as a percentage of base salary listed below, modified by company and individual performance. Name 2024 Target Bonus Rate (% of base salary) Steven Nichtberger, M.D. 55 % Gwendolyn K. Binder, Ph.D. 40 % David J. Chang, M.D., M.P.H. 40 % Company performance was assessed as achievement of 2024 company objectives, including certain clinical development, business development and financial and operational goals and development of a strong team culture. As a result, the compensation committee recommended and our board of directors approved 2024 company achievement at 108%. The compensation committee recommended (and/or approved) and the board of directors approved (as applicable, in the instance of the chief executive officer), a further adjustment of bonuses based on the individual achievement of each of the named executive officers, as noted below: Name Individual Achievement (%) Steven Nichtberger, M.D. 114 % Gwendolyn K. Binder, Ph.D. 115 % David J. Chang, M.D., M.P.H. 125 % Long-term equity incentives Our equity grant program is intended to align the interests of our named executive officers with those of our stockholders and to motivate them to make important contributions to our performance. In 2024, we granted stock options to each of our named executive officers, as reflected in the “Outstanding Equity Awards at 2024 Fiscal Year End Table” below. Employment arrangements with our named executive officers In October 2019, we entered into amended and restated employment agreements with each of our named executive officers. Each of our named executive officers is employed at will. Steven Nichtberger, M.D. Under his amended and restated employment agreement, Dr. Nichtberger is entitled to an annual base salary, which is subject to review and redetermination by our board of directors or our compensation committee, and he is eligible to receive an annual bonus determined by our board of directors or the compensation committee (subject to the terms of any applicable incentive compensation plan that may be in effect from time to time), with a target amount calculated as a percentage of his annual base salary. Dr. 121 Nichtberger is also eligible to participate in the employee benefit plans available to our employees, subject to the terms of those plans, and is reimbursed for his existing, personal life insurance policy premiums. Dr. Nichtberger’s employment agreement provides that, in the event that his employment is terminated by us without “cause” or by him for “good reason,” then subject to the execution and effectiveness of a separation agreement and release and compliance with his continuing obligations, he will be entitled to receive (i) an amount equal to (x) 12 months of base salary payable on our normal payroll cycle if such termination occurs outside of the period commencing 60 days before and ending 12 months after the occurrence of the first event constituting a “change in control”, or the Change in Control Period, or (y) 1.5 times the sum of his base salary plus his target bonus for the then-current year payable on our or our successor’s normal payroll cycle over 18 months if such termination occurs within Change in Control Period; (ii) payment of the monthly employer COBRA premium for the same level of group health coverage as in effect for Dr. Nichtberger on the date of termination for up to (x) 12 months if such termination occurs outside of the Change in Control Period, and (y) 18 months if such termination occurs within the Change in Control Period; and (iii) full acceleration of all stock options and other stock-based awards held by Dr. Nichtberger if such termination occurs within the Change in Control Period. In addition to standard good reason triggers, Dr. Nichtberger may elect to resign for good reason if within six months following the appointment of a chairperson of the board of directors, Dr. Nichtberger provides written notice of his reasonable dissatisfaction with such chairperson and the board fails to designate a new chairperson within 30 days of such notice. In the event of such a resignation for good reason outside of the Change in Control Period, subject to the execution and effectiveness of a separation agreement and release and compliance with his continuing obligations, in addition to the severance benefits described above, all stock options and other stock-based awards held by Dr. Nichtberger will accelerate and become fully exercisable or nonforfeitable. The payments and benefits provided to Dr. Nichtberger under his employment agreement in connection with a sale event may not be eligible for a federal income tax deduction for the company pursuant to Section 280G of the Code. These payments and benefits also may be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Nichtberger in connection with a sale event would be subject to the excise tax on golden parachutes imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after tax benefit to Dr. Nichtberger. In addition, Dr. Nichtberger has entered into a non-competition, non-solicitation, confidentiality and assignment agreement with us that contains, among other things, non-competition and non-solicitation provisions that apply during the term of Dr. Nichtberger’s employment and for 12 months thereafter. Gwendolyn K. Binder, Ph.D. Under her amended and restated employment agreement, Dr. Binder is entitled to an annual base salary, which is subject to review and redetermination by our board of directors or our compensation committee, and she is eligible to earn an annual bonus with a target amount calculated as a percentage of her base salary. Dr. Binder is also eligible to participate in the employee benefit plans available to our employees, subject to the terms of those plans. Dr. Binder’s employment agreement provides that, in the event that her employment is terminated by us without “cause” or by her for “good reason,” then subject to the execution and effectiveness of a separation agreement and release and compliance with her continuing obligations, she will be entitled to receive (i) an amount equal to (x) nine months of base salary payable on our normal payroll cycle if such termination occurs outside of the Change in Control Period or (y) a lump sum in cash in the amount of 1.0 times the sum of her base salary plus her target bonus for the then-current year payable on our or our successor’s normal payroll cycle over 12 months if such termination is occurs within the Change in Control Period; (ii) payment of the monthly employer COBRA premium for the same level of group health coverage as in effect for Dr. Binder on the date of termination up to (x) nine months if such termination occurs outside of the Change in Control Period, and (y) 12 months if such termination occurs within the Change in Control Period; and (iii) full acceleration of all stock options and other stock-based awards subject to time-based vesting held by Dr. Binder if such termination occurs within the Change in Control Period. The payments and benefits provided to Dr. Binder under her employment agreement in connection with a sale event may not be eligible for a federal income tax deduction for the company pursuant to Section 280G of the Code. These payments and benefits also may be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Binder in connection with a sale event would be subject to the excise tax on golden parachutes imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to such officer. In addition, Dr. Binder has entered into a non-competition, non-solicitation, confidentiality and assignment agreement with us that contains, among other things, non-competition and non-solicitation provisions that apply during the term of Dr. Binder’s employment and for 12 months thereafter. 122 David J. Chang, M.D., M.P.H. Under his amended and restated employment agreement, Dr. Chang is entitled to an annual base salary, which is subject to review and redetermination by our board of directors or our compensation committee, and he is eligible to earn an annual bonus with a target amount calculated as a percentage of his base salary. Dr. Chang is also eligible to participate in the employee benefit plans available to our employees, subject to the terms of those plans. Dr. Chang’s employment agreement provides that, in the event that his employment is terminated by us without “cause” or by him for “good reason,” then subject to the execution and effectiveness of a separation agreement and release and compliance with his continuing obligations, he will be entitled to receive (i) an amount equal to (x) nine months of base salary payable on our normal payroll cycle if such termination occurs outside of the Change in Control Period or (y) a lump sum in cash in the amount of 1.0 times the sum of his base salary plus his target bonus for the then-current year payable on our or our successor’s normal payroll cycle over 12 months if such termination occurs within the Change in Control Period; (ii) payment of the monthly employer COBRA premium for the same level of group health coverage as in effect for Dr. Chang on the date of termination up to (x) nine months if such termination occurs outside of the Change in Control Period, and (y) 12 months if such termination occurs outside of the Change in Control Period; and (iii) full acceleration of all stock options and other stock-based awards subject to time-based vesting held by Dr. Chang if such termination occurs within the Change in Control Period. The payments and benefits provided to Dr. Chang under his employment agreement in connection with a sale event may not be eligible for a federal income tax deduction for the company pursuant to Section 280G of the Code. These payments and benefits also may be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Chang in connection with a sale event would be subject to the excise tax on golden parachutes imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to such officer. In addition, Dr. Chang has entered into a non-competition, non-solicitation, confidentiality and assignment agreement with us that contains, among other things, non-competition and non-solicitation provisions that apply during the term of Dr. Chang’s employment and for 12 months thereafter. 123 Outstanding Equity Awards at 2024 Fiscal Year End Table The following table presents information regarding all outstanding stock awards and stock options held by each of our named executive officers as of December 31, 2024. Option awards Stock awards Name Number of Securities Underlying Unexercised Options (#) Exercisable Number of Securities Underlying Unexercised Options (#) Unexercisable Option Exercise Price ($) Option Expiration Date Number of Shares or Units of Stock that Have Not Vested (#) Market Value of Shares or Units of Stock that Have Not Vested ($) Steven Nichtberger, M.D. 186,451 229,677 99,714 300,000 312,656 261,250 180,075 — — —(1) —(2) —(3) 20,844(7) 118,750(8) 231,525(9) 353,000(10) 1.01 1.01 11.00 14.94 11.47 3.21 11.09 23.97 10/28/2028 10/28/2028 10/23/2029 2/28/2030 2/28/2031 1/17/2032 1/17/2033 2/28/2034 — — — — — — — — — — — — — — — — Gwendolyn K. Binder, Ph.D. 100,756 66,667 29,908 117,188 110,000 77,000 — —(4) —(5) —(2) 7,812(7) 50,000(8) 99,000(9) 130,000(10) 1.01 9.54 11.00 11.47 3.21 11.09 23.97 10/28/2028 8/21/2029 10/23/2029 2/28/2031 1/17/2032 1/17/2033 2/28/2034 — — — — — — — — — — — — — — David J. Chang, M.D., M.P.H. 185,709 48,836 38,238 106,406 92,813 65,625 — —(6) —(2) — (3) 7,094(7) 42,187(8) 84,375(9) 130,000(10) 6.30 11.00 14.94 11.47 3.21 11.09 23.97 6/23/2029 10/23/2029 2/28/2030 2/28/2031 1/17/2032 1/17/2033 2/28/2034 — — — — — — — — — — — — — — (1) These options vest over four years, with 25% vesting on October 11, 2019, and the remaining shares vesting in 36 equal monthly installments thereafter, subject to a continued service relationship with us. (2) These options vest over four years, with 25% vesting on October 24, 2020, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (3) These options vest over four years, with 25% vesting on March 1, 2021, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (4) These options vest over four years, with 25% vesting on October 11, 2019 and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (5) These options vest over four years, with 25% vesting on August 22, 2020, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (6) These options vest over four years, with 25% vesting on June 17, 2020, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (7) These options vest over four years, with 25% vesting on March 1, 2022, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (8) These options vest over four years, with 25% vesting on January 18, 2023, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (9) These options vest over four years, with 25% vesting on January 18, 2024, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. (10) These options vest over four years, with 25% vesting on March 1, 2025, and the remaining shares vesting in 12 equal quarterly installments thereafter, subject to a continued service relationship with us. 124 Additional Narrative Disclosure 401(k) Savings Plan. We participate in a retirement savings plan, or 401(k) plan, that is intended to qualify for favorable tax treatment under Section 401(a) of the Code, and contains a cash or deferred feature that is intended to meet the requirements of Section 401(k) of the Code. U.S. employees who are at least 21 years of age are generally eligible to participate in the 401(k) plan, subject to certain criteria. Participants may make pre-tax and certain after-tax (Roth) salary deferral contributions to the plan from their eligible earnings up to the statutorily prescribed annual limit under the Code. Participants who are 50 years of age or older may contribute additional amounts based on the statutory limits for catch-up contributions. Participant contributions are held in trust as required by law. An employee’s interest in his or her salary deferral contributions is 100% vested when contributed. We have the ability to make discretionary contributions under the plan and all eligible employees will receive a Safe Harbor matching contribution up to 4% of eligible pay for the 2024 plan year. Health and Welfare Benefits . All of our full-time employees, including our executive officers are eligible to participate in certain medical, disability and life insurance benefit programs offered by us. We pay the premiums for term life insurance and long-term disability for all of our employees, including our executive officers. We also provide all employees, including executive officers, with a flexible spending account plan and paid time off benefits including, vacation, sick time and holidays. We do not sponsor any qualified or non-qualified defined benefit plans for any of our employees or executives. Compensation Risk Assessment We believe that although a portion of the compensation provided to our executive officers and other employees is performance-based, our executive compensation program does not encourage excessive or unnecessary risk taking. Our compensation programs are designed to encourage our executive officers and other employees to remain focused on both short-term and long-term strategic goals, in particular in connection with our pay-for-performance compensation philosophy. As a result, we do not believe that our compensation programs are reasonably likely to have a material adverse effect on us. Policy on Trading, Pledging and Hedging of Company Stock Certain transactions in our securities (such as purchases and sales of publicly traded put and call options, and short sales) create a heightened compliance risk or could create the appearance of misalignment between management and stockholders. In addition, securities held in a margin account or pledged as collateral may be sold without consent if the owner fails to meet a margin call or defaults on the loan, thus creating the risk that a sale may occur at a time when an officer or director is aware of material, non-public information or otherwise is not permitted to trade in Company securities. Our insider trading policy expressly prohibits short sales and derivative transactions of our stock by our executive officers, directors, employees and certain designated consultants and contractors, including short sales of our securities. Our insider trading policy expressly prohibits, without the advance approval of our audit committee, purchases or sales of puts, calls, or other derivative securities of the company or any derivative securities that provide the economic equivalent of ownership. Compensation Recovery Policy (Clawback Policy) On September 12, 2023, we adopted a Compensation Recovery Policy, or the Clawback Policy, in compliance with the requirements of the Dodd-Frank Act, final SEC rules and applicable Nasdaq listing standards (the “final clawback rules”), which covers our current and former executive officers, including all of our named executive officers. Under the Clawback Policy, in the event that we are required to prepare a restatement of our previously issued financial statements due to our material noncompliance with any financial reporting requirement under securities laws, we are required to recover (subject to certain limited exceptions described in the Clawback Policy and permitted under the final clawback rules) any cash or equity incentive-based compensation received by any current or former executive officer after the effective date of the Clawback Policy and in the three years prior to the date we are required to restate our financial statements that is in excess of the amount that would have been received based on the restated financial statements. Compensation Committee Interlocks and Insider Participation Each of Richard Henriques, Mark Simon and Shawn Tomasello, served on the compensation committee during fiscal year 2024. No member of the compensation committee has ever been an officer or employee of the Company. None of our executive officers serve, or have served during the last fiscal year, as a member of the board of directors, compensation committee, or other 125 board committee performing equivalent functions of any other entity that has one or more executive officers serving as one of our directors or on our compensation committee. Policy on the Timing of Awards of Options and Other Option-Like Instruments Our compensation committee has generally granted annual equity awards, including stock option grants to our named executive officers, in the first quarter of each fiscal year, specifically early March. In addition, new hires receive stock option grants at the time of their hiring. Eligible employees, including our named executive officers, may voluntarily enroll in our Employee Stock Purchase Plan and receive an option to purchase shares at a discount using payroll deductions accumulated during the prior six months, with purchase dates occurring in May and November. During 2024, our compensation committee did not take into account any material nonpublic information when determining the timing and terms of equity incentive awards, and we did not time the disclosure of material nonpublic information for the purpose of affecting the value of executive compensation. During 2024, we did not grant stock options to our named executive officers during any period beginning four business days before and ending one business day after the filing or furnishing of a Form 10-Q, 10-K or 8-K that discloses material nonpublic information. Please see Item 10 for details regarding corporate governance, including the composition of our compensation committee, as required by Regulation S-K 407(e)(4) and (e)(5). Director Compensation The following table presents the total compensation for each person who served as a non-employee member of our board of directors and received compensation for such service during the fiscal year ended December 31, 2024. Other than as set forth in the table and described more fully below, we did not pay any compensation, make any equity awards or non-equity awards to, or pay any other compensation to any of the non-employee members of our board of directors in 2024. We reimburse members of our board of directors for reasonable travel expenses. Dr. Nichtberger, our Chief Executive Officer and President, did not receive any compensation for his service as a member and Chairman of our board of directors in 2024. Dr. Nichtberger’s compensation for service as an employee for fiscal years 2024 and 2023 is presented in “Executive Compensation—2024 Summary Compensation Table.” Name Fees Earned or Paid In Cash ($) Option Awards (1)(2) All Other Compensation Total ($) Catherine Bollard, MBChB, M.D. 60,000 181,810 — 241,810 Scott Brun, M.D. 65,000 181,810 — 246,810 Richard Henriques, MBA 60,500 181,810 — 242,310 Mark Simon, MBA 63,500 181,810 — 245,310 Shawn Tomasello, MBA 53,000 181,810 — 234,810 (1) Amount shown reflects the grant date fair value of an option award granted during 2024. The grant date fair value was computed in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 718, Compensation—Stock Compensation, or FASB ASC Topic 718, disregarding the effect of estimated forfeitures related to service-based vesting. See Note 10 to the financial statements in our 2024 Annual Report on Form 10-K regarding assumptions we made in determining the fair value of option awards. (2) As of December 31, 2024, the aggregate number of shares subject to option awards held by our non-employee directors were: Dr. Bollard: 134,428; Dr. Brun: 110,000; Mr. Henriques: 134,428; Mr. Simon: 134,428 and Ms. Tomasello 66,000. As of December 31, 2024, the aggregate number of unvested shares outstanding held by our non-employee directors were: Dr. Bollard: 22,000; Dr. Brun: 22,000; Mr. Henriques: 22,000; Mr. Simon: 22,000 and Ms. Tomasello 47,667. Amended and Restated Non-Employee Director Compensation Policy Under our director compensation policy, we pay our non-employee directors a cash retainer for service on the board of directors and for service on each committee on which the director is a member. The chairman of each committee receives a higher retainer for such service. These fees are payable in arrears in four equal quarterly installments on the last day of each quarter, provided that the amount of such payment is prorated for any portion of such quarter that the director is not serving on our board of directors. The fees paid to non-employee directors for service on the board of directors and for service on each committee of the board of directors on which the director is a member for 2024 are as follows: 126 Member Annual Retainer ($) Chairperson Annual Retainer ($) Board of Directors 40,000 — Audit Committee 7,500 15,000 Compensation Committee 5,500 11,000 Nominating and Corporate Governance Committee 5,000 10,000 Science and Technology Committee 7,500 15,000 In February 2025, we amended our director compensation policy. Accordingly, the fees paid to non-employee directors for service on the board of directors and for service on each committee of the board of directors on which the director is a member for 2025 are as follows: Member Annual Retainer ($) Chairperson Annual Retainer ($) Board of Directors 40,000 — Audit Committee 10,000 20,000 Compensation Committee 6,250 12,500 Nominating and Corporate Governance Committee 5,000 10,000 Science and Technology Committee 7,500 15,000 We also reimburse our non-employee directors for reasonable out-of-pocket expenses incurred in connection with attending our board of director and committee meetings. In addition, each new non-employee director elected to our board of directors will be granted an initial, one-time award of a stock option to purchase 44,000 shares, which shall vest in equal quarterly installments over a three-year period from the date of vesting commencement, subject to continued service as a director through each such vesting date. In addition, on the date of each annual meeting of stockholders of our company, each non-employee director will receive an annual stock option award of 22,000 shares, which shall vest in full upon the earlier to occur of the first anniversary of the date of grant or the date of the next annual meeting provided , however , that all vesting shall cease if the director resigns from the board of directors or otherwise ceases to serve as a director, unless the board of directors determines that the circumstances warrant continuation of vesting. This program is intended to provide a total compensation package that enables us to attract and retain qualified and experienced individuals to serve as directors and to align our directors’ interests with those of our stockholders. 127 Item 12. Security Ownership of Certain Beneficial Own ers and Management and Related Stockholder Matters. Equity Compensation Plan Information The following table provides information as of December 31, 2024 regarding shares of common stock that may be issued under our equity compensation plans, consisting of the 2018 Plan, the 2019 Plan and the 2019 Employee Stock Purchase Plan, or the ESPP. We have no equity compensation plans that were not approved by security holders. Plan Category Number of securities to be issued upon exercise of outstanding options, units and rights (#) Weighted-average exercise price of outstanding options, units and rights ($) Number of securities remaining available for future issuance under equity compensation plan (excluding securities referenced in first column) Equity compensation plans approved by security holders(1) 11,231,148(2) $ 10.63 1,693,564(3)(4) Equity compensation plans not approved by security holders — — — Total 11,231,148 $ 10.63 1,693,564 (1) Consists of our 2019 Stock Option and Incentive Plan, 2018 Stock Option and Grant Plan, and 2019 Employee Stock Purchase Plan. Following our initial public offering, we have not and will not grant any awards under our 2018 Stock Option and Grant Plan, but all outstanding awards under the 2018 Stock Option and Grant Plan will continue to be governed by their existing terms. The shares of common stock underlying any awards granted under the 2018 Stock Option and Grant Plan or 2019 Stock Option and Incentive Plan that are forfeited, canceled, reacquired by us prior to vesting, satisfied without the issuance of stock, or otherwise terminated (other than by exercise) and the shares of common stock that are withheld upon exercise of a stock option or settlement of such award to cover the exercise price or tax withholding will be added to the shares of common stock available for issuance under the 2019 Stock Option and Incentive Plan. (2) Includes 11,231,148 shares of common stock issuable upon the exercise of outstanding options, of which 1,235,458 are subject to our 2018 Stock Option and Grant Plan and 9,995,690 are subject to our 2019 Stock Option and Incentive Plan. (3) As of December 31, 2024, there were 1,379,305 shares available for grant under the 2019 Stock Option and Incentive Plan and 314,259 shares available for grants under the 2019 Employee Stock Purchase Plan. (4) The 2019 Stock Option and Incentive Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2020, by 4% of the outstanding number of shares of our common stock on the immediately preceding December 31. The 2019 Employee Stock Purchase Plan provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2020, through January 1, 2029, by the least of 234,229 shares of our common stock, 1% of the outstanding number of shares of our common stock on the immediately preceding December 31, or such lesser number of shares as determined by our compensation committee. Security Ownership of Certain Beneficial Owners and Management The following table sets forth information, to the extent known by us or ascertainable from public filings, with respect to the beneficial ownership of our common stock as of March 7, 2025 by: • each of our directors; • each of our named executive officers; • all of our directors and executive officers as a group; and • each person, or group of affiliated persons, who is known by us to beneficially own greater-than-5.0% of our common stock. The column entitled “Shares Beneficially Owned” is based on a total of 50,743,101 shares of our common stock outstanding as of March 7, 2025. Beneficial ownership is determined in accordance with the rules and regulations of the SEC and includes voting or investment power with respect to our common stock. Shares of our common stock subject to options or warrants that are currently exercisable or exercisable within 60 days of March 7, 2025 are considered outstanding and beneficially owned by the person holding the options or warrants for the purpose of calculating the percentage ownership of that person but not for the purpose of calculating the percentage ownership of any other person. Except as otherwise noted, the persons and entities in this table have sole voting and investing power with respect to all of the shares of our common stock beneficially owned by them, subject to community property 128 laws, where applicable. Except as otherwise indicated in the table below, addresses of named beneficial owners are in care of Cabaletta Bio, Inc., 2929 Arch Street, Suite 600, Philadelphia, Pennsylvania 19104. Shares beneficially owned Name and address of beneficial owner(1) Number Percentage > 5% Stockholders: BlackRock, Inc.(2) 3,397,260 6.7% Entities Affiliated with Adage Capital Partners, L.P.(3) 3,634,475 7.2% T. Rowe Price Investment Management, Inc.(4) 3,673,724 7.2% Entities affiliated with Prudential Financial, Inc.(5) 2,798,863 5.5% Bain Capital Life Sciences Opportunities III, LP(6) 2,760,888 5.4% The Vanguard Group(7) 2,553,710 5.0% Named Executive Officers and Directors: Steven Nichtberger, M.D.(8) 3,127,350 5.95% Gwendolyn K. Binder, Ph.D.(9) 603,831 1.18% David Chang, M.D., M.P.H.(10) 612,846 1.19% Catherine Bollard, MBChB, M.D.(11) 113,428 0.22% Scott Brun, M.D.(12) 88,000 0.17% Richard Henriques, MBA(13) 112,428 0.22% Mark Simon, MBA(14) 255,572 0.50% Shawn Tomasello, MBA(15) 25,667 0.05% All executive officers and directors as a group (11 persons)(15) 6,056,069 10.96% * Represents beneficial ownership of less than one percent. (1) Unless otherwise indicated, the address for each beneficial owner is c/o Cabaletta Bio, Inc., 2929 Arch Street, Suite 600, Philadelphia, Pennsylvania 19104. (2) The information reported is based on information in a Schedule 13G/A, as filed by BlackRock, Inc. with the SEC on February 5, 2025. In that filing, BlackRock, Inc. reports sole voting power with respect to 3,329,097 shares of common stock and sole dispositive power with respect to 3,397,260 shares, and lists its address as 50 Hudson Yards, New York, New York 10001. (3) The information is based on a Schedule 13G/A filed with the SEC on November 12, 2024. Consists of 3,036,645 shares of common stock and 597,830 shares of common stock issuable upon the exercise of pre-funded warrants held by Adage Capital Partners, L.P., or ACP. Adage Capital Partners GP, L.L.C., or ACPGP, is the general partner of ACP. Adage Capital Management, L.P., or ACM, is the investment manager of ACP. Adage Capital Advisors, L.L.C., or ACA, is managing member of ACPGP. Adage Capital Partners LLC, or ACPLLC , is the general partner of ACM, with respect to the shares of voting common stock directly held by ACP. Robert Atchinson and Phillip Gross are managing members of ACA and ACPGP and are general partners of ACP. Each of ACP, ACPGP, ACA, ACM, Robert Atchinson, and Phillip Gross have shared voting and dispositive power over all of the shares. The ability of the Adage entities to exercise their pre-funded warrants is subject to a beneficial ownership limitation, which prevents the Adage entities from exercising any portion of the warrants to the extent such exercise would result in the Adage entities exceeding a certain percentage of the total number of issued and outstanding shares of our common stock following such exercise. The address for Adage Capital Partners, L.P. is 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116. (4) The information reported is based on information in a Schedule 13G/A, as filed by T. Rowe Price Investment Management, Inc. (Price Investment Management) with the SEC on November 14, 2024. In that filing, T. Rowe Price Investment Management, Inc. (Price Investment Management) reports sole voting power with respect to 3,666,024 shares of common stock and sole dispositive power with respect to 3,673,724 shares, and lists its address as 101 E. Pratt Street, Baltimore, MD 21201. (5) The information reported is based on information in a Schedule 13G/A, as filed by Prudential Financial, Inc. with the SEC on December 5, 2024. In that filing, Prudential Financial, Inc. reports shared voting and dispositive power over (i) 2,796,053 shares of our common stock, being 2,512,053 shares held through its subsidiary Jennison Associates LLC and 284,000 shares held through its subsidiary PGIM, Inc., and (ii) sole voting and dispositive power over 2,810 shares of our common stock held through its subsidiary PGIM Quantitative Solutions LLC. The address provided for Prudential Financial, Inc. is 751 Broad Street, New Jersey 07102. (6) The information reported is based on information in a Schedule 13G, as filed by Bain Capital Life Sciences Opportunities III, LP with the SEC on August 22, 2024. In that filing, Bain Capital Life Sciences Opportunities III, LP reports shared voting power and shared dispositive power with respect to 2,760,888 shares of common stock. Bain Capital Life Sciences Investors, LLC, or BCLSI, is the manager of Bain Capital Life Sciences III General Partner, LLC, which is the general partner of Bain Capital Life Sciences Fund III, L.P., which is the sole member of Bain Capital Life Sciences Opportunities III GP, LLC, which is the general partner of Bain Capital Life Sciences Opportunities III, LP. As a result, BCLSI may be deemed to share voting and dispositive power with respect to the securities held by Bain Capital Life Sciences Opportunities III, LP. The address of BCLSI is 200 Clarendon Street, Boston, MA 02116. 129 (7) The information reported is based on information in a Schedule 13G/A, as filed by The Vanguard Group with the SEC on November 12, 2024. In that filing, The Vanguard Group reports shared voting power with respect to 31,135 shares of common stock, sole dispositive power with respect to 2,500,994 shares and shared dispositive power with respect to 52,716 shares, and lists its address as 100 Vanguard Blvd., Malvern, PA 19355. (8) Consists of (i) 986,483 shares of common stock held by Dr. Nichtberger, (ii) 363,000 shares of common stock held by the 2017 Nichtberger Family Trust, or the Trust Shares, and (iii) 1,177,867 shares of common stock underlying options exercisable within 60 days of March 7, 2025. Dr. Nichtberger may be deemed to beneficially own the Trust Shares. Dr. Nichtberger disclaims beneficial ownership of the Trust Shares and this shall not be deemed an admission that he is the beneficial owner of the Trust Shares. (9) Consists of (i) 20,000 shares of common stock held and (ii) 583,831shares of common stock underlying options exercisable within 60 days of March 7, 2025. (10) Consists of 612,846 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (11) Consists of (i) 1,000 shares of common stock held and (ii) 112,428 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (12) Consists of 88,000 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (13) Consists of 112,428 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (14) Consists of (i) 143,144 shares of common stock held and (ii) 112,428 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (15) Consists of 25,667 shares of common stock underlying options exercisable within 60 days of March 7, 2025. (16) See notes (7) through (14); also includes an aggregate of (i) 50,000 shares of common stock and (ii) 1,066,947 shares of common stock subject to options exercisable within 60 days of March 7, 2025 held by Anup Marda, our Chief Financial Officer, Michael Gerard, our General Counsel and Secretary, and Arun Das, M.D., our Chief Business Officer. 130 Item 13. Certain Relationships and Related Transactions, and Director Independence. Certain Relationships and Transactions Other than the compensation agreements and other arrangements described under “Executive compensation” and “Director compensation” in this Annual Report on Form 10-K for the fiscal year ended December 31, 2024 and the transactions described below, since January 1, 2023, there has not been and there is not currently proposed, any transaction or series of similar transactions to which we were, or will be, a party in which the amount involved exceeded, or will exceed, $120,000 (or, if less, 1% of the average of our total assets amounts at December 31, 2023 and 2024) and in which any director, executive officer, holder of five percent or more of any class of our capital stock or any member of the immediate family of, or entities affiliated with, any of the foregoing persons, had, or will have, a direct or indirect material interest. May 2023 Offering In May 2023, we issued 8,337,500 shares of our common stock at a price of $12.00 per share in connection with an underwritten public offering. Certain existing holders of five percent or more of a class of our capital stock participated in the transaction, as evidenced by the table below. Greater than Five Percent Holder Aggregate Common Stock Purchased Aggregate Purchase Price Adage Capital Partners LP 725,000 $ 8,700,000 Fred Alger Management Inc 400,000 $ 4,800,000 Cormorant Global Healthcare Master Fund LP 400,000 $ 4,800,000 Commodore Capital LP 400,000 $ 4,800,000 Limitation of Liability and Indemnification of Officers and Directors Our certificate of incorporation contains provisions that limit the liability of our directors for monetary damages to the fullest extent permitted by Delaware law. Consequently, our directors will not be personally liable to us or our stockholders for monetary damages for any breach of fiduciary duties as directors, except liability for the following: • any breach of their duty of loyalty to our company or our stockholders; • any act or omission not in good faith or that involves intentional misconduct or a knowing violation of law; • unlawful payments of dividends or unlawful stock repurchases or redemptions as provided in Section 174 of the Delaware General Corporation Law; or • any transaction from which they derived an improper personal benefit. Any amendment to, or repeal of, these provisions will not eliminate or reduce the effect of these provisions in respect of any act, omission or claim that occurred or arose prior to that amendment or repeal. If the Delaware General Corporation Law is amended to provide for further limitations on the personal liability of directors of corporations, then the personal liability of our directors will be further limited to the greatest extent permitted by the Delaware General Corporation Law. In addition, we adopted bylaws which provide that we will indemnify, to the fullest extent permitted by law, any person who is or was a party or is threatened to be made a party to any action, suit or proceeding by reason of the fact that he or she is or was one of our directors or officers or is or was serving at our request as a director or officer of another corporation, partnership, joint venture, trust, or other enterprise. Our bylaws provide that we may indemnify to the fullest extent permitted by law any person who is or was a party or is threatened to be made a party to any action, suit, or proceeding by reason of the fact that he or she is or was one of our employees or agents or is or was serving at our request as an employee or agent of another corporation, partnership, joint venture, trust or other enterprise. Our bylaws also provide that we must advance expenses incurred by or on behalf of a director or officer in advance of the final disposition of any action or proceeding, subject to very limited exceptions. We have entered into and in the future plan to enter into agreements to indemnify our directors and executive officers. These agreements, among other things, require us to indemnify these individuals for certain expenses (including attorneys’ fees), judgments, fines and settlement amounts reasonably incurred by such person in any action or proceeding, including any action by or in our right, on account of any services undertaken by such person on behalf of our company or that person’s status as a member of our board of directors to the maximum extent allowed under Delaware law. 131 Related person transaction policy Our board of directors adopted a written related person transaction policy providing that transactions with our directors, officers and holders of five percent or more of our voting securities and their affiliates, each a related person, must be approved by our audit committee. This policy became effective on October 29, 2019, the date our registration statement for our initial public offering became effective. Pursuant to this policy, the audit committee has the primary responsibility for reviewing and approving or disapproving “related person transactions,” which are transactions between us and related persons in which the aggregate amount involved exceeds or may be expected to exceed $120,000 and in which a related person has or will have a direct or indirect material interest. For purposes of this policy, a related person is defined as a director, executive officer, nominee for director, or greater than 5% beneficial owner of our common stock, in each case since the beginning of the most recently completed year, and their immediate family members. As appropriate for the circumstances, the audit committee will review and consider: • the related person’s interest in the related person transaction; • the approximate dollar amount involved in the related person transaction; • the approximate dollar amount of the related person’s interest in the transaction without regard to the amount of any profit or loss; • whether the transaction was undertaken in the ordinary course of our business; • whether the terms of the transaction are no less favorable to us than terms that could have been reached with an unrelated third party; • the purpose of, and the potential benefits to us of, the related-party transaction; and • any other information regarding the related-party transaction or the related person in the context of the proposed transaction that would be material to investors in light of the circumstances of the particular transaction. Director Independence Applicable Nasdaq rules require a majority of a listed company’s board of directors to be comprised of independent directors within one year of listing. In addition, the Nasdaq rules require that, subject to specified exceptions, each member of a listed company’s audit, compensation and nominating and corporate governance committees be independent and that audit committee members also satisfy independence criteria set forth in Rule 10A-3 under the Exchange Act and that compensation committee members satisfy independence criteria set forth in Rule 10C-1 under the Exchange Act. Under applicable Nasdaq rules, a director will only qualify as an “independent director” if, in the opinion of the listed company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In order to be considered independent for purposes of Rule 10A-3, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors, or any other board committee, accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the listed company or any of its subsidiaries or otherwise be an affiliated person of the listed company or any of its subsidiaries. In addition, in affirmatively determining the independence of any director who will serve on a company’s compensation committee, Rule 10C-1 under the Exchange Act requires that a company’s board of directors must consider all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director’s ability to be independent from management in connection with the duties of a compensation committee member, including: the source of compensation to the director, including any consulting, advisory or other compensatory fee paid by such company to the director, and whether the director is affiliated with the company or any of its subsidiaries or affiliates. Our board of directors has determined that all members of the board of directors, except Dr. Nichtberger are independent directors, including for purposes of the rules of Nasdaq and the SEC. In making such independence determination, our board of directors considered the relationships that each non-employee director has with us and all other facts and circumstances that our board of directors deemed relevant in determining their independence, including the beneficial ownership of our capital stock by each non-employee director. In considering the independence of the directors listed above, our board of directors considered the association of our directors with the holders of more than 5% of our common stock. There are no family relationships among any of our directors or executive officers. Dr. Nichtberger is not an independent director under these rules because he is an executive officer of the Company. 132 Item 14. Principal Accountant Fees and Services. Our independent public accounting firm is Ernst & Young, Philadelphia, PA, PCAOB Auditor ID 42 . Cabaletta incurred the following fees from Ernst & Young for the audit of the financial statements and for other services provided during the years ended December 31, 2024 and 2023. 2024 2023 Audit fees(1) $ 646,500 $ 830,000 Audit-Related fees(2) — — Tax fees(3) 66,950 65,000 All other fees(4) — — Total fees $ 713,450 $ 895,000 (1) Audit fees consist of fees for the audit of our annual financial statements, the review of our interim financial statements included in our quarterly reports on Form 10-Q, comfort letters and consents. (2) Audit-related fees consist of services that are reasonably related to the performance of the audit or review of our financial statements. There were no such fees incurred in 2024 or 2023. (3) Tax Fees consist of fees for tax compliance, advice and tax services. (4) There were no other fees incurred in 2024 or 2023. Audit Committee Pre-approval Policy and Procedures Our audit committee has adopted policies and procedures relating to the approval of all audit and non-audit services that are to be performed by our independent registered public accounting firm. This policy provides that we will not engage our independent registered public accounting firm to render audit or non-audit services unless the service is specifically approved in advance by our audit committee or the engagement is entered into pursuant to the pre-approval procedure described below. From time to time, our audit committee may pre-approve specified types of services that are expected to be provided to us by our independent registered public accounting firm during the next 12 months. Any such pre-approval details the particular service or type of services to be provided and is also generally subject to a maximum dollar amount. During our 2024 and 2023 fiscal years, no services were provided to us by Ernst & Young other than in accordance with the pre-approval policies and procedures described above. 133 PART IV Item 15. Exhibits, Consolidated Financ ial Statement Schedules. (a) The following documents are filed as part of this Annual Report on Form 10-K: (1) Consolidated Financial Statements: Page Report of Independent Registered Public Accounting Firm F- 2 Consolidated Balance Sheets as of December 31, 2024 and 2023 F- 4 Consolidated Statements of Operations and Comprehensive Loss for the Years Ended December 31, 2024 and 2023 F- 5 Consolidated Statements of Stockholders’ Equity for the Years Ended December 31, 2024 and 2023 F- 6 Consolidated Statements of Cash Flows for the Years Ended December 31, 2024 and 2023 F- 7 Notes to Consolidated Financial Statements F- 8 (2) Consolidated Financial Statement Schedules: All consolidated financial statement schedules have been omitted because they are not applicable, not required or the information required is shown in the consolidated financial statements or the notes thereto. (3) Exhibits. The exhibits required by Item 601 of Regulation S-K and Item 15(b) of this Annual Report on Form 10-K are listed in the Exhibit Index immediately preceding the signature page of this Annual Report on Form 10-K. The exhibits listed in the Exhibit Index are incorporated by reference herein. Item 16. Form 10-K Summary None. 134 INDEX TO FINANCIAL STATEMENTS Page Report of Independent Registered Public Accounting Firm F- 2 Consolidated Balance Sheets as of December 31, 2024 and 2023 F- 4 Consolidated Statements of Operations and Comprehensive Loss for the Years Ended December 31, 2024 and 2023 F- 5 Consolidated Statements of Stockholders’ Equity for the Years Ended December 31, 2024 and 2023 F- 6 Consolidated Statements of Cash Flows for the Years Ended December 31, 2024 and 2023 F- 7 Notes to Consolidated Financial Statements F- 8 F- 1 Report of Independent Regist ered Public Accounting Firm To the Stockholders and the Board of Directors of Cabaletta Bio, Inc. Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Cabaletta Bio, Inc. (the Company) as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles. The Company's Ability to Continue as a Going Concern The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the consolidated financial statements, the Company has suffered recurring losses from operations and has stated that substantial doubt exists about the Company’s ability to continue as a going concern. Management's evaluation of the events and conditions and management’s plans regarding these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. Basis for Opinion These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion. F- 2 Critical Audit Matter The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the account or disclosures to which it relates. Accounting for Accrued Clinical Trial Expenses Description of the Matter As disclosed in Note 2 to the consolidated financial statements, the Company expenses research and development costs as incurred, which include costs relating to clinical trial activities. The Company’s accrued clinical trial expenses are based on factors such as estimates of the work completed in accordance with agreements established with a contract research organization. As disclosed in Note 5 to the consolidated financial statements, the Company’s total accrued expenses and other current liabilities related to research and development costs were $3.5 million at December 31, 2024, which included the estimated clinical trial expenses incurred as of December 31, 2024 but not paid as of that date. Auditing the Company’s accrued clinical trial expenses required subjective auditor judgement due to the estimation required by management in determining the services provided but not yet invoiced. Specifically, the amount of accrued clinical trial expenses recognized is sensitive to the availability of information to make the estimate, including the estimate of the period over which services will be performed, the associated cost of such services, and the level of services performed and progress in the period for which the Company has not yet received an invoice. How We Addressed the Matter in Our Audit To test the accrued clinical trial expenses our audit procedures included, among others, reviewing a sample of agreements with the service providers to corroborate key financial and contractual terms, and testing the accuracy and completeness of the underlying data used in the accrual expense computations. We also evaluated management’s estimates of the progress of a sample of clinical trial activities by making inquiries of the Company’s operations personnel that oversee the clinical trials and confirming information directly with the contract research organization. To evaluate the completeness of the accruals, we also examined subsequent invoices from the service providers and cash disbursements to the service providers, to the extent such invoices were received, or payments were made prior to the date that the consolidated financial statements were issued. /s/ Ernst & Young LLP We have served as the Company’s auditor since 2018. Philadelphia, Pennsylvania March 31, 2025 F- 3 CABALETTA BIO, INC. Consolidated Balance Sheets (in thousands, except share and per share amounts) December 31, 2024 2023 Assets Current assets: Cash and cash equivalents $ 163,962 $ 193,238 Short-term investments — 48,011 Prepaid expenses and other current assets 2,713 3,241 Total current assets 166,675 244,490 Property and equipment, net 2,743 2,541 Finance lease right-of-use assets 7,020 — Operating lease right-of-use assets 6,315 4,910 Other assets 2,293 1,709 Total Assets $ 185,046 $ 253,650 Liabilities and stockholders’ equity Current liabilities: Accounts payable $ 4,923 $ 4,547 Accrued and other current liabilities 12,188 7,887 Finance lease liabilities, current portion 5,989 — Operating lease liabilities, current portion 3,986 3,560 Total current liabilities 27,086 15,994 Finance lease liabilities, net of current portion 3,241 — Operating lease liabilities, net of current portion 2,384 1,458 Total Liabilities 32,711 17,452 Commitments and contingencies (see Notes 6 and 7) Stockholders’ equity: Preferred stock, $ 0.00001 par value: 10,000,000 shares authorized as of December 31, 2024 and December 31, 2023; no shares issued or outstanding at December 31, 2024 and December 31, 2023 — — Voting and non-voting common stock, $ 0.00001 par value: 150,000,000 ( 143,590,481 voting and 6,409,519 non-voting) shares authorized as of December 31, 2024 and December 31, 2023; 50,743,101 voting shares issued and outstanding as of December 31, 2024 and 47,823,232 ( 46,378,937 voting and 1,444,295 non-voting) shares issued and outstanding as of December 31, 2023 1 — Additional paid-in capital 501,435 469,396 Accumulated other comprehensive income — 39 Accumulated deficit ( 349,101 ) ( 233,237 ) Total stockholders’ equity 152,335 236,198 Total liabilities and stockholders’ equity $ 185,046 $ 253,650 The accompanying notes are an integral part of these consolidated financial statements. F- 4 CABALETTA BIO, INC. Consolidated Statements of Operations and Comprehensive Loss (in thousands, except share and per share amounts) Year Ended December 31, 2024 2023 Operating expenses: Research and development $ 97,203 $ 55,424 General and administrative 27,938 19,236 Total operating expenses 125,141 74,660 Loss from operations ( 125,141 ) ( 74,660 ) Other income: Interest income 10,025 6,985 Interest expense ( 748 ) — Net loss $ ( 115,864 ) $ ( 67,675 ) Other comprehensive income: Net unrealized (loss) gain on available-for-sale investments, net of tax ( 39 ) 86 Net comprehensive loss $ ( 115,903 ) $ ( 67,589 ) Net loss per share of voting and non-voting common stock, basic and diluted $ ( 2.34 ) $ ( 1.65 ) The accompanying notes are an integral part of these consolidated financial statements. F- 5 CABALETTA BIO, INC. Consolidated Statements of Stockholders’ Equity (in thousands, except share and per share amounts) Common Stock Shares Amount Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Accumulated Deficit Total Stockholders’ Equity Balance—December 31, 2022 29,445,134 $ — $ 270,129 $ ( 47 ) $ ( 165,562 ) $ 104,520 Stock-based compensation — — 11,343 — — 11,343 Issuance of common stock, net of issuance costs of $ 8,647 13,098,399 — 185,495 — — 185,495 Issuance of common stock in connection with exercise of stock options 489,672 — 2,321 — — 2,321 Issuance of common stock under employee stock purchase plan 16,053 — 108 — — 108 Issuance of common stock upon exercise of pre-funded warrants 4,773,974 — — — — — Net unrealized losses on available-for-sale securities — — — 86 — 86 Net loss — — — — ( 67,675 ) ( 67,675 ) Balance—December 31, 2023 47,823,232 $ — $ 469,396 $ 39 $ ( 233,237 ) $ 236,198 Stock-based compensation — — 19,465 — — 19,465 Issuance of common stock, net of issuance costs of $ 252 1,483,070 1 10,875 — — 10,876 Issuance of common stock in connection with exercise of stock options 210,695 — 1,430 — — 1,430 Issuance of common stock under employee stock purchase plan 58,056 — 269 — — 269 Issuance of common stock upon exercise of pre-funded warrants 1,168,048 — — — — — Net unrealized losses on available-for-sale securities — — — ( 39 ) — ( 39 ) Net loss — — — — ( 115,864 ) ( 115,864 ) Balance—December 31, 2024 50,743,101 $ 1 $ 501,435 $ — $ ( 349,101 ) $ 152,335 The accompanying notes are an integral part of these consolidated financial statements. F- 6 CABALETTA BIO, INC. Consolidated Statements of Cash Flows (in thousands) Year Ended December 31, 2024 2023 Cash flows from operating activities: Net loss $ ( 115,864 ) $ ( 67,675 ) Adjustments to reconcile net loss to net cash used in operating activities: Stock-based compensation 19,465 11,343 Depreciation 1,711 1,426 Amortization of finance lease 3,102 — Non-cash operating lease expense 2,838 2,070 Accretion of operating lease liabilities 405 408 Amortization of discount on investments ( 1,528 ) ( 1,222 ) Loss on foreign currency exchange rates 38 — Changes in operating assets and liabilities: Prepaid expenses and other current assets 528 ( 954 ) Other assets ( 584 ) ( 1,144 ) Accounts payable 1,011 1,675 Accrued and other current liabilities 3,947 2,980 Lease liabilities ( 3,291 ) ( 2,456 ) Net cash used in operating activities ( 88,222 ) ( 53,549 ) Cash flows from investing activities: Purchases of property and equipment ( 2,211 ) ( 687 ) Purchases of investments — ( 84,264 ) Proceeds from maturities of investments 49,500 62,500 Net cash provided by (used in) investing activities 47,289 ( 22,451 ) Cash flows from financing activities: Proceeds from the issuance of common stock, net of issuance costs 10,875 185,202 Proceeds from issuance of common stock in connection with the exercise of stock options 1,430 2,321 Proceeds from issuance of common stock under employee stock purchase plan 269 108 Principal payments on finance leases ( 897 ) — Net cash provided by financing activities 11,677 187,631 Effect of exchange rate changes on cash and cash equivalents ( 20 ) — Net (decrease) increase in cash and cash equivalents ( 29,276 ) 111,631 Cash and cash equivalents—beginning of period 193,238 81,607 Cash and cash equivalents—end of period $ 163,962 $ 193,238 Supplemental disclosures Cash paid for interest $ 748 $ — Property and equipment purchases included in accounts payable and accrued expenses $ 404 $ 702 Right-of-use assets obtained in exchange for finance lease obligations $ 10,963 $ 2,048 Right-of-use assets obtained in exchange for operating lease obligations $ 4,242 $ — The accompanying notes are an integral part of these consolidated financial statements. F- 7 CABALETTA BIO, INC. Notes to the Consolidated Financial Statements (in thousands, except share and per share amounts) 1. Basis of Presentation Cabaletta Bio, Inc. (the Company or Cabaletta) was incorporated in April 2017 in the State of Delaware as Tycho Therapeutics, Inc. and, in August 2018, changed its name to Cabaletta Bio, Inc. The consolidated financial statements include the accounts of Cabaletta Bio and its wholly owned subsidiaries: Cabaletta Bio GmbH and Cabaletta Bio (Germany) GmbH. All intercompany balances and transactions have been eliminated in consolidation. The Company is headquartered in Philadelphia, Pennsylvania. Cabaletta is a clinical-stage biotechnology company focused on the discovery and development of engineered T cell therapies for autoimmune diseases. Principal operations commenced in April 2018. Risks and Uncertainties The Company does not expect to generate revenue from sales of engineered T cell therapies for autoimmune diseases or any other revenue unless and until the Company completes preclinical and clinical development and obtains regulatory approval for one or more product candidates. If the Company seeks to obtain regulatory approval for any of its product candidates, the Company expects to incur significant commercialization expenses. The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. As a result, the Company is unable to predict the timing or amount of increased expenses or when or if the Company will be able to achieve or maintain profitability. Further, the Company is dependent on third parties for certain research and development activities, including manufacturing services (Note 6 and Note 7). Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. Even if the Company is able to generate revenues from the sale of its product candidates, if approved, it may not become profitable. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations. Liquidity and Going Concern In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, ("ASC 205-40") the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern. The Company has sustained annual operating losses since inception and expects to continue to generate operating losses for the foreseeable future. As of December 31, 2024, the Company has incurred an accumulated deficit of $ 349,101 and has a cash and cash equivalents balance of $ 163,962 . The Company’s ultimate success depends on the outcome of its research and development activities. Management expects to incur additional losses in the future as it continues its research and development and will need to raise additional capital to fully implement its business plan and to fund its operations. The Company intends to raise such additional capital through a combination of equity offerings, debt financings, government funding arrangements, strategic alliances or other sources. However, if such financing is not available at adequate levels and on a timely basis, or such agreements are not available on favorable terms, or at all, as and when needed, the Company will need to reevaluate its operating plan and may be required to delay or discontinue the development of one or more of its product candidates or operational initiatives. The Company expects that its current cash and cash equivalents may not be sufficient to fund operations for at least the next twelve months from the date of issuance of these consolidated financial statements. The Company's cash forecast contains estimates and assumptions based on success of ongoing clinical trials, and management cannot predict the amount or timing of all expenditures with certainty. Accordingly, the Company has concluded that substantial doubt exists about the Company’s ability to continue as a going concern. The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. F- 8 2. Summary of Significant Accounting Policies Principles of Consolidation The accompanying consolidated financial statements included herein have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP") and under the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include but are not limited to advance payments and accruals related to the Company’s research and development expenses . The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. Off-Balance Sheet Risk and Concentrations of Credit Risk Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist of cash and cash equivalents, which are invested in U.S. treasury-based money market funds. As of December 31, 2023, the Company held available-for-sale securities, which were invested in U.S. treasury securities. These investments matured in 2024. A portion of the Company’s cash is maintained at two federally insured financial institutions, and account balances may at times exceed federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk. The Company has no off‑balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts. Investments Investments are available-for-sale and carried at estimated fair value. The Company’s valuations of available-for-sale debt securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. Management determines the appropriate classification of its investments in debt securities at the time of purchase and at the end of each reporting period. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than, twelve months from the balance sheet date are classified as current. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive income. The Company periodically evaluates whether declines in fair values of its available-for-sale securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors including the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or if more likely than not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. Realized gains and losses and declines in fair value judged to be other-than-temporary, if any, on available-for-sale securities are included in interest and other income, net. The cost of investments sold is based on the specific-identification method. Interest income on investments as well as amortization of discount or premium is included in interest income. F- 9 Property, Plant and Equipment Property, plant and equipment are recorded at cost less accumulated depreciation. Cost includes the acquisition costs and all costs necessary to bring the asset to the location and working condition necessary for its intended use. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the accompanying statements of operations. Expenditures for normal, recurring or periodic repairs and maintenance related to property and equipment are charged to expense as incurred. The cost for planned major maintenance activities, including the related acquisition or construction of assets, is capitalized if it will result in future economic benefits. Estimated useful lives for property and equipment are as follows: Property and equipment Estimated useful life Laboratory equipment Three years Furniture and fixtures Three years Computer equipment Three years Leasehold improvements Lesser of estimated useful life or remaining lease term Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Leases The Company has leases related to its facilities used for offices and laboratory space, which are classified as operating leases as well as leases related to its manufacturing arrangements, which are classified as finance leases. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease and its classification based on the unique facts and circumstances present in the arrangement. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets and current and non-current lease liabilities, as applicable. Lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments. Subsequent to the initial measurement, the Company will continue to account for: • the lease liability at the net present value using the incremental borrowing rate that was in effect as of the lease commencement, lease modification, or transition date, and; F- 10 • the finance lease and operating lease expense on a straight line basis. Leases with terms of 12 months or less are considered short-term leases and right-of-use assets and lease obligations are not recognized. Payments associated with short-term leases are expensed on a straight-line basis over the lease term. In accordance with ASC 842, components of a lease should be split into three categories: lease components, non-lease components and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) must be allocated based on the respective relative fair values to the lease components and non-lease components. Entities may elect not to separate lease and non-lease components. Rather, entities would account for each lease component and related non-lease component together as a single lease component. The Company has elected to aggregate all lease and non-lease components for each class of underlying assets into a single lease component for real-estate leases and embedded manufacturing arrangements. ASC 842 allows for the use of judgment in determining whether the assumed lease term is for a major part of the remaining economic life of the underlying asset and whether the present value of lease payments represents substantially all of the fair value of the underlying asset. The Company applies the guidance in ASC 842-10-55-2 to assist in determining lease classification across its leases. Research and Development Expenses Research and development costs include costs incurred for internal and external research and development activities and are expensed as incurred in the accompanying statements of operations. Research and development costs consist of salaries and benefits, including associated stock-based compensation, and laboratory supplies and facility costs, as well as fees paid to entities that conduct certain research and development and clinical trial activities on the Company’s behalf. The Company records accrued liabilities for estimated costs of research and development activities conducted by service providers, which include preclinical studies, contract manufacturing activities and clinical trial activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided and in accordance with agreements established with service providers and includes these costs in accrued and other current liabilities in the accompanying balance sheets and within research and development expense in the accompanying statements of operations. Non-refundable advance payments made for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as expense as the goods are received or the related services are rendered. The Company makes significant judgments and estimates in determining the accrued liabilities and prepaid expenses in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities and prepaid expenses. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception. Stock-based Compensation The Company measures its stock-based awards granted to employees and non-employees based on the estimated fair values of the awards on the respective grant dates. The Company uses the Black-Scholes option-pricing model (Black-Scholes) to estimate the fair value of its stock-based awards. The Company recognizes compensation expense for time-based awards on a straight-line basis over the requisite service period, which is generally the vesting period of the award. The Company accounts for forfeitures of stock option awards as they occur. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax base, as well as for net operating loss carryforwards and research and development credits, and are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. F- 11 Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, the Company concludes that it is more-likely-than-not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. Because of the uncertainty of the realization of deferred tax assets, the Company has recorded a full valuation allowance against its deferred tax assets. Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more-likely-than-not to be sustained on examination by a taxing authority, assuming they possess full knowledge of the position and facts. Interest and penalties related to uncertain tax positions are recognized in the provision of income taxes; however, the Company currently has no interest or penalties related to uncertain income tax benefits. Net Loss Per Share The Company calculates basic and diluted net loss per share in conformity with the two-class method required for participating securities because the Company had both voting and non-voting common stock outstanding in 2023 and for a portion of 2024. The rights, including the liquidation and dividend rights, of the holders of the voting and non-voting common stock are identical, except with respect to voting. Each share of non-voting common stock may be converted at any time into one share of voting common stock at the option of its holder by providing written notice to the Company, subject to the limitations provided for in the amended and restated certificate of incorporation. As of December 31, 2024, no shares of non-voting common stock remain outstanding. Basic net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted average number of shares of common stock, including any pre-funded warrants to purchase shares of common stock that may be outstanding. The undistributed loss for each year is allocated to common stockholders based on the contractual participation rights of the voting and non-voting common stock as if the losses for the year had been distributed. As the liquidation and dividend rights are identical, the undistributed losses are allocated on a proportionate basis. Diluted net loss per share attributable to common stockholders is computed under the if-converted method and assumes that all non-voting common stock has been converted to common stock. Since the Company was in a loss position for all periods presented, the effects of the other potentially dilutive securities are antidilutive. Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (CODM) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer (CEO). The Company has determined it operates in a single operating segment and has one reportable segment. Refer to Note 8 – Segment Reporting for further information related to our segment. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded as a reduction to the carrying value of stockholders’ equity as a reduction of additional paid-in capital or equity generated as a result of such offering. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss. Emerging Growth Company Status Prior to December 31, 2024, the Company was an “emerging growth company” (EGC) as defined in the Jumpstart Our Business Startups Act, (JOBS Act), and elected to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies until the Company no longer qualifies as an EGC, including using the extended transition period for complying with new or revised accounting standards. As of December 31, 2024, the Company ceased to qualify as an EGC. F- 12 Recently Adopted Accounting Pronouncements In November 2023, the FASB issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures . This ASU requires that a public entity provide additional segment disclosures on an interim and annual basis. The amendments in this ASU should be applied retrospectively to all prior periods presented in the consolidated financial statements, unless impracticable. Upon transition, the segment expense categories and amounts disclosed in the prior periods should be based on the significant segment expense categories identified and disclosed in the period of adoption. The Company adopted this ASU for the annual period ended December 31, 2024 and the amendments have been applied retrospectively to all prior periods presented in the financial statements. Refer to Note 8 – Segment Reporting for further information related to our segment. Recently Issued Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures . ASU 2023-09 enhances the transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is effective for public business entities for annual periods beginning after December 15, 2024. Early adoption is permitted. This update is effective beginning with the Company’s 2025 fiscal year annual reporting period. The Company is currently planning to adopt this guidance when effective and is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes. In November 2024, the FASB issued ASU 2024-03, Income Statement (Subtopic 220-40): Reporting Comprehensive Income-Expense Disaggregation Disclosures. ASU 2024-03 requires enhanced disclosures about components of expense captions on the face of the income statement. This standard will be effective for fiscal years beginning after December 15, 2026. Early adoption is permitted. ASU 2024-03 applies on a prospective basis for periods beginning after the effective date. However, retrospective application to any or all prior periods presented is permitted. The Company is currently planning to adopt this guidance when effective and is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes. There have been no other new accounting pronouncements or changes to accounting pronouncements that, if adopted, would have or may have a material impact on the Company’s consolidated statements or disclosures. F- 13 3. Fair Value Measurements As of December 31, 2024 and 2023, the Company’s financial instruments included cash and cash equivalents, available-for-sale debt securities, accounts payable and accrued expenses. The carrying amounts for cash and cash equivalents, accounts payable and accrued expenses reported in the Company’s consolidated financial statements for these instruments approximate their respective fair values because of the short-term nature of these instruments. The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: December 31, 2024 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial assets Cash equivalents: Money market funds $ 162,634 $ 162,634 $ — $ — Short-term investments: U.S. Treasury securities — — — — Total $ 162,634 $ 162,634 $ — $ — December 31, 2023 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial assets Cash equivalents: Money market funds $ 180,124 $ 180,124 $ — $ — U.S. Treasury securities - original maturity less than three months 12,371 — 12,371 — Short-term investments: U.S. Treasury securities 48,011 — 48,011 — Total $ 240,506 $ 180,124 $ 60,382 $ — F- 14 Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as Level 1. Investments are measured at fair value based on inputs other than quoted prices that are derived from observable market data and are classified as Level 2 inputs. For debt securities classified as available-for-sale investments, the Company records unrealized gains or losses resulting from changes in fair value between measurement dates as a component of other comprehensive income. The Company did not hold any available-for-sale securities as of December 31, 2024: December 31, 2023 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair value Financial assets Cash $ 743 $ — $ — $ 743 Money market funds 180,124 — — 180,124 U.S. Treasury securities - original maturity less than three months 12,367 4 — 12,371 Included in cash and cash equivalents 193,234 4 — 193,238 U.S. Treasury securities - due in one year or less Included in short-term investments 47,976 39 ( 4 ) 48,011 Total $ 241,210 $ 43 $ ( 4 ) $ 241,249 F- 15 4. Property, Plant and Equipment Property, plant and equipment consists of the following: December 31, 2024 2023 Laboratory equipment $ 7,663 $ 5,893 Furniture and fixtures 277 277 Computer equipment 196 53 Leasehold improvements 113 113 Total property, plant and equipment 8,249 6,336 Less: accumulated depreciation ( 5,506 ) ( 3,795 ) Property, plant and equipment, net $ 2,743 $ 2,541 Depreciation expense was $ 1,711 and $ 1,426 for the years ended December 31, 2024 and 2023, respectively. 5. Accrued and Other Current Liabilities Accrued and other current liabilities consist of the following: December 31, 2024 2023 Research and development services $ 3,491 $ 2,459 General and administrative services 342 188 Compensation expense 8,315 5,200 Other 40 40 $ 12,188 $ 7,887 6. Collaborations, Licensing Agreements and other Agreements Amended and Restated License Agreement with the Trustees of the University of Pennsylvania and Children’s Hospital of Philadelphia In August 2018, the Company entered into a license agreement with Penn, as amended and restated in July 2019 to include the Children’s Hospital of Philadelphia (CHOP) as a party, and as amended in May 2020 and October 2021 (the License Agreement) pursuant to which the Company obtained (a) a non-exclusive, non-sublicensable worldwide license to certain of Penn’s intellectual property to conduct research, product development, clinical trials, cell manufacturing and other activities, and (b) an exclusive, worldwide, royalty-bearing right and license, with a right to sublicense, on a target-by-target basis, under certain of Penn’s intellectual property to make, use, sell, offer for sale, import, and otherwise commercialize products for the treatment of autoimmune and alloimmune diseases. Unless earlier terminated, the License Agreement expires on the expiration or abandonment or other termination of the last valid claim in Penn’s intellectual property licensed by the Company. The Company may terminate the License Agreement at any time for convenience upon 60 days' written notice. In the event of an uncured, material breach, Penn may terminate the License Agreement upon 60 days' written notice. Under the terms of the License Agreement, the Company was obligated to pay $ 2,000 annually for three years beginning August 2018 for funding to the laboratories of each of Drs. Milone and Payne. This was satisfied through completed sponsored research agreements with a total cost of $ 12,560 . During the term of the License Agreement until the first commercial sale of the first product, the Company is obligated to pay Penn a non-refundable, non-creditable annual license maintenance fee of $ 10 . In May 2020, the Company paid Penn an additional, non-refundable, non-creditable license fee of $ 33 under the amended License Agreement. F- 16 The Company is required to pay certain milestone payments upon the achievement of specified clinical and commercial milestones. Milestone payments are reduced by a certain percentage for the second product that achieves a milestone, by an additional percentage for the third product that achieves a milestone, and so on, for each subsequent product that achieves a milestone. In the event that the Company is able to successfully develop and launch multiple products under the License Agreement, total milestone payments could be approximately $ 21,000 . Penn is also eligible to receive tiered royalties at percentage rates in the low single-digits, subject to an annual minimum royalty, on annual worldwide net sales of any products that are commercialized by the Company or its sublicensees that contain or incorporate, or are covered by, the intellectual property licensed by the Company. To the extent the Company sublicenses its license rights under the License Agreement, Penn would be eligible to receive tiered sublicense income at percentage rates in the mid-single to low double-digits. There were no amounts due under the License Agreement as of December 31, 2024. Master Translational Research Services Agreement In October 2018 and February 2023, the Company entered into services agreements (the CAART and CARTA Services Agreements) with Penn for research, development and manufacturing services from various laboratories within Penn. The activities are detailed in separately executed Penn organization-specific addenda. In May 2020, the Company amended its Addendum with the Center for Advanced Retinal and Ocular Therapeutics (CAROT) to expand access to vector manufacturing. Research and development expense related to executed addenda under the master translational research service agreements with Penn recognized in the accompanying statements of operations was $ 3,250 and $ 3,786 for the years ended December 31, 2024 and 2023, respectively. The Company is committed to pay up to $ 3,000 under the CARTA Services Agreement for cell processing manufacturing through December 31, 2025. The Company may incur additional expenses up to $ 643 t hrough the remaining term of the CAROT Amended Addendum. Exclusive License Agreement with IASO Biotherapeutics On October 7, 2022, the Company entered into an Exclusive License Agreement (the IASO Agreement) with Nanjing IASO Biotherapeutics Co., Ltd. (IASO). Pursuant to the IASO Agreement, the Company received an exclusive, worldwide license under certain IASO intellectual property to use a novel clinical-stage anti-CD19 binder to develop, manufacture, commercialize and otherwise exploit T cell products directed to CD19 for the purpose of diagnosis, prevention or treatment of any autoimmune or alloimmune indications in humans. As partial consideration for the exclusive license, IASO received an upfront payment of $ 2,500 . IASO is also eligible to receive up to mid double digit millions in milestone payments based upon the achievement of specified pre-clinical, development and regulatory milestones, and up to an additional low triple digit millions in milestone payments based upon achievement of specified sales milestones, for a total consideration, inclusive of the upfront payment, of up to $ 162,000 , along with tiered mid-single digit royalties on future net sales for licensed products that may result from the IASO Agreement. Upon the U.S. Food and Drug Association’s clearance of the rese-cel Investigational New Drug application for the treatment of systemic lupus erythematosus in March 2023, a milestone payment of $ 1,000 was recognized in the accompanying statements of operations. A milestone payment of $ 1,500 was paid to IASO in the first quarter of 2024 after the first patient in a rese-cel trial was dosed. IASO has the right of first negotiation if the Company desires to grant a third party an exclusive license to develop, manufacture, commercialize or otherwise exploit the licensed products in the Greater China region. Pursuant to the IASO Agreement, each of IASO and the Company have agreed, subject to certain exceptions, to refrain from engaging in certain competitive activities with respect to certain programs. The Company also may sublicense through multiple tiers the rights granted to it by IASO under the IASO Agreement at any time, however, it must pay IASO a low double-digit percentage of any revenue obtained from sublicenses or options to third parties, subject to certain customary exclusions. The IASO Agreement will continue on a country-by-country, licensed product-by-licensed product basis until the expiration of the royalty term as identified in the IASO Agreement, unless earlier terminated. Each of the Company and IASO may terminate the Agreement for a material, uncured breach or insolvency of the other party. The Company may also terminate the Agreement at will upon advance written notice and in the event IASO rejects the Agreement due to bankruptcy-related matters. IASO may also terminate the Agreement if the Company fails to achieve certain specified diligence milestones in a timely manner and/or if the Company commences any patent challenges with respect to the patents and patent applications relating to the licensed sequence, in each case upon advance written notice. F- 17 Licence and Supply Agreement with Oxford Biomedica In December 2021, the Company entered into a Licence and Supply agreement (LSA) with Oxford Biomedica (UK) Limited (Oxford), wherein the LSA grants the Company a non-exclusive license to Oxford’s LentiVector® platform for its application in the Company’s DSG3-CAART program and put in place a multi-year vector supply agreement. Under the terms of the agreement, the Company was required to pay Oxford an upfront fee, as well as costs associated with initial vector manufacturing activities for a total cost incurred of $ 1,100 . Oxford is eligible to receive regulatory and sales milestones in the low tens of millions and royalties in the low single digits on net sales of products that incorporate the Oxford technology. In May 2023, the Company amended the LSA with Oxford to expand the license to include the Company's rese-cel program for an upfront fee of $ 500 , and in August 2023, the Company and Oxford entered into a vector supply agreement for rese-cel, and a related second amendment to the LSA, with a total cost under the vector supply agreement of up to approximately $ 5,000 , of which approximately $ 3,500 and $ 1,500 were recognized as research and development expense for the years ended December 31, 2024 and 2023, respectively. In February 2024, the Company and Oxford entered into a third amendment to the LSA to update the patent schedule. In June 2024, the Company and Oxford entered into a fourth amendment to the LSA elimin ating royalties on net sales of products that incorporate the Oxford technology if Oxford manufactures the vector. In December 2024, the Company and Oxford entered into a work order with a cost of approximately $ 9,000 for certain process characterization activities as part of commercial readiness activities. The Company can terminate the LSA or any work order under the LSA at will upon advance written notice and subject to certain cancellation fees. Option and License Agreement with Autolus In January 2023, the Company entered into an Option and License Agreement (Autolus Agreement) with Autolus Holdings (UK) Limited (Autolus), wherein the Autolus Agreement granted the Company a non-exclusive license to access Autolus' RQR8 technology in its CD19-CAR T cell therapy program, and subject to additional nominal option exercise fees, up to four additional t argets. In January 2025, the Company and Autolus agreed to novate the Autolus Agreement with both Autolus and Autolus Limited jointly assuming the rights, obligations and liabilities of Autolus, under the Autolus Agreement. Under the terms of the Autolus Agreement, the Company was required to pay Autolus an upfront license fee of $ 1,200 that was recognized as expense in the first quarter of 2023 in the accompanying statements of operations, of which $ 1,100 was paid in 2023 and $ 100 was paid in January 2024. Autolus is also eligible to receive regulatory milestones of up to $ 12,000 for each licensed target, sales milestones of up to a total of $ 15,000 and royalties in the low single digits on net sales of all products that incorporate the RQR8 technology. The Autolus Agreement will continue on a country-by-country, licensed product-by-licensed product basis until the expiration of the royalty term as identified in the Autolus Agreement, unless earlier terminated. The Company can terminate the Autolus Agreement at will upon advance written notice. Each of the Company and Autolus may terminate the Agreement for a material, uncured breach or insolvency of the other party. 7. Commitments and Contingencies Manufacturing Agreements In January 2021, the Company entered into a Development and Manufacturing Services Agreement (WuXi Agreement) with WuXi Advanced Therapies, Inc. (WuXi) to serve as an additional cell processing manufacturing partner for the MuSK-CAART Phase 1 clinical trial, or MusCAARTes TM trial. The WuXi Agreement is scheduled to expire upon completion of WuXi's services related to MuSK-CAART and rese-cel. In August 2023, and as extended in August 2024, the Company entered into an agreement with WuXi to serve as one of the Company's manufacturing partners for the global clinical development of rese-cel in multiple indications, including potential late-stage clinical trials and commercial readiness activities for rese-cel. Under the August 2023 work orders, WuXi converted the Company’s non-dedicated suite to a dedicated suite for GMP manufacturing for the Company’s rese-cel and MuSK-CAART programs, or the Dedicated Suite, for an initial term of 18 months with two 18-month extensions at the Company’s sole option on six months' notice prior to the end of the term. In August 2024, the Company sent a notice to WuXi to extend the initial term of the WuXi Agreement by 18 months through August 2026. In addition, the Company agreed to certain monthly minimum runs. In August 2024, the 2023 work order related to GMP manufacturing was amended to reduce the minimum monthly runs through the end of 2024. In lieu of the original $ 1,500 termination fee under the terms of the WuXi Agreement, the Company would incur up to a $ 1,080 termination fee if it terminates both the rese-cel and MuSK-CAART work orders for any reason. The Company may terminate for F- 18 convenience the WuXi Agreement or any work order with six months' prior written notice. However, the Company may not terminate the Dedicated Suite without terminating both the MuSK-CAART and rese-cel GMP run work orders. WuXi may terminate for convenience the WuXi Agreement or any work order on 18 months' prior written notice, but such notice may not be effective prior to February 2028. In December 2024, the Company entered into a Development and Manufacturing Services Agreement (the Lonza Agreement) with Lonza Houston Inc. (Lonza) to serve as one of the Company's manufacturing partners for the global clinical development of rese-cel in multiple indications, including potential late-stage clinical trials and preparations for commercial readiness. Under the initial work order, Lonza will perform cell therapy manufacturing activities for Cabaletta’s CAR-T cell therapy product rese-cel for a term of 12 months and total cost of approximately $ 16,000 with the ability to extend the manufacturing period subject to the terms of the Lonza Agreement. Other Purchase Commitments In the normal course of business, the Company enters into various purchase commitments with third-party contract manufacturers for the manufacture and processing of its product candidates and related raw materials, contracts with contract research organizations for clinical trials and agreements with vendors for other services and products for operating purposes. These agreements generally provide for termination or cancellation, other than for costs already incurred. Indemnification The Company enters into certain types of contracts that contingently require the Company to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company’s Amended and Restated Bylaws, as amended, (bylaws) under which the Company must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers and consultants for liabilities arising out of their relationship, (iii) contracts under which the Company may be required to indemnify partners against certain claims, including claims from third parties asserting, among other things, infringement of their intellectual property rights, and (iv) procurement, consulting, or license agreements under which the Company may be required to indemnify vendors, consultants or licensors for certain claims, including claims that may be brought against them arising from the Company’s acts or omissions with respect to the supplied products, technology or services. From time to time, the Company may receive indemnification claims under these contracts in the normal course of business. In addition, under these contracts, the Company may have to modify the accused infringing intellectual property and/or refund amounts received. In the event that one or more of these matters were to result in a claim against the Company, an adverse outcome, including a judgment or settlement, may have a material adverse effect on the Company’s future business, operating results or financial condition. It is not possible to determine the maximum potential amount under these contracts due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. Litigation From time to time, the Company may become involved in litigation or legal proceedings. While the outcome of any such proceedings cannot be predicted with certainty, as of December 31, 2024, the Company is not involved in any material litigation or legal proceedings that it would expect to have a material adverse impact on its financial position, results of operations, or cash flows. 8. Segment Information Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the CODM in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is the CEO. The Company has determined that it has one operating and reportable segment. The segment consists of the development of clinical and preclinical product candidates for the discovery and development of innovative engineered T cell therapies and related administrative activities. The F- 19 CODM assesses performance and allocates resources based on the Company’s consolidated statement of operations, which is reported on the income statement as consolidated net loss and considers forecast-to-actuals variances on a quarterly basis for expenses that are deemed significant. Further, the CODM reviews the segment’s assets based on the consolidated balance sheet to assess liquidity and funding capacity. The majority of the Company's assets are located in the United States. The Company’s CODM views specific categories within expenses as significant given the direct correlation between cash burn and profitability as a pre-revenue company. Significant segment expenses, as provided to the CODM, are presented below. For additional information on the year over year change of segment expenses refer to Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations. Year Ended December 31, 2024 2023 (in thousands) Research and development expenses: Personnel $ 39,239 $ 22,375 Clinical trials 22,286 8,302 Development services 16,417 12,486 Manufacturing of preclinical and clinical supplies 15,523 8,498 License of intellectual property 1,523 2,383 Other research and development costs (1) 2,215 1,380 General and administration expenses 27,938 19,236 Interest income ( 10,025 ) ( 6,985 ) Interest expense 748 — Net loss $ 115,864 $ 67,675 (1) Other research and development costs includes costs associated with information technology, travel, medical and scientific symposiums and conferences. 9 . Leases The Company leases office and laboratory space in addition to a manufacturing agreement which has been determined to contain an embedded lease. Operating lease commitments The Company leases office and laboratory space which include rent escalations and are subject to additional variable charges, including common area maintenance, property taxes and property insurance. Given the variable nature of such costs, they are recognized as expense as incurred. Additionally, some of the Company’s leases are subject to certain fixed fees which the Company has determined to be non-lease components. The Company has elected the practical expedient to account for lease and non-lease components as a single-lease component and has included fixed payments related to non-lease components in calculating the operating lease liability. In 2024, the Company extended the terms of its lab and office operating leases and leased additional lab space resulting in an increase in the right-of-use asset and lease liability of $ 4,242 . Finance lease commitments - Embedded leases As described further in Note 7, in August 2023, the Company entered into new work orders under the WuXi Agreement for WuXi to serve as one of the Company’s cell processing manufacturing partners for the global clinical development of rese-cel. WuXi converted the Company’s non-dedicated suite to a Dedicated Suite for GMP manufacturing for the Company’s rese-cel and MuSK-CAART programs, for an initial term of 18 months. The terms of the August 2023 work orders included both fixed costs and contingent variable costs. The lease commenced October 1, 2023. In 2024, the Company remeasured the lease due to resolution of the contingency related to variable costs and an amendment to the 2023 work order to extend the term of the agreement for an additional 18 months through August F- 20 2026 resulting in an increase in the right-of-use asset and lease liability of $ 10,963 . The Company may terminate the Dedicated Suite lease for convenience with six months’ prior written notice and up to a $ 1,080 termination fee if both the rese-cel and MuSK-CAART work orders are terminated . As described further in Note 7, in December 2024, the Company entered into the Lonza Agreement with Lonza to serve as one of our manufacturing partners. Under the initial work order, Lonza will perform cell therapy manufacturing activities for our CAR-T cell therapy product rese-cel for a term of 12 months and total cost of approximately $ 16,000 with the ability to extend the manufacturing period subject to the terms of the Lonza Agreement. The Lonza Agreement is currently being evaluated for lease accounting under ASC 842. No right-of-use asset or liability was recognized as of December 31, 2024, as lease commencement begins in fiscal year 2025. Summary of lease costs recognized under ASC 842 The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating and finance leases for the years ended December 31, 2024 and 2023. For the year ended December 31, 2024 2023 Finance leases Interest expense $ 748 $ — Amortization expense 3,102 — Total fixed finance lease cost $ 3,850 $ — Variable lease cost 930 — Total finance lease cost $ 4,780 $ — Operating leases Fixed lease cost $ 3,247 $ 2,477 Total fixed operating lease cost $ 3,247 $ 2,477 Variable lease cost 296 65 Short-term lease cost 750 717 Total operating lease cost $ 4,293 $ 3,259 Cash paid in the measurement of lease liabilities Operating cash flows used for operating leases $ 3,291 $ 2,456 Operating cash flows used for finance leases 748 — Financing cash flows for finance leases 897 — Other information Weighted average remaining lease term - finance leases (in years) 1.7 — Weighted average discount rate - finance leases 11.5 % — Weighted average remaining lease term - operating leases (in years) 1.7 1.5 Weighted average discount rate - operating leases 11.0 % 9.5 % F- 21 For finance leases embedded in CDMO arrangements, interest expense is recognized using the effective interest method, applying the Company's incremental borrowing rate as required by ASC 842, and amortization expense is recognized on a straight-line basis over the shorter of the life of the asset or the term of the lease. Future lease payments under the non-cancelable operating and finance leases as of December 31, 2024 are as follows : Finance Leases Operating Leases 2025 $ 6,328 $ 4,227 2026 3,792 2,769 Total undiscounted lease payments 10,120 6,996 Less imputed interest ( 890 ) ( 626 ) Total lease liability $ 9,230 $ 6,370 10. Common Stock Common Stock Pursuant to the Company’s Third Amended and Restated Certificate of Incorporation filed in October 2019, the Company is authorized to issue 143,590,481 shares of voting common stock and 6,409,519 shares of non-voting common stock. Holders of voting common stock shall have the exclusive right to vote for the election of directors of the Company and on all other matters requiring stockholder action. Each share of the Company’s non-voting common stock may be converted at any time into one share of common stock at the option of its holder by providing 61 days written notice to the Company , subject to certain limitations, as described in the amended and restated certificate of incorporation. In May 2024, 1,444,295 shares of non-voting common stock was converted to voting common stock and no shares of non-voting common stock remain outstanding. May 2023 Financing In May 2023, the Company issued 8,337,500 shares of its common stock in an underwritten public offering, including the exercise in full by the underwriters of their option to purchase an additional 1,087,500 shares, at a public offering price of $ 12.00 per share. Aggregate net proceeds were $ 93,755 after deducting underwriting discounts and commissions and offering expenses of $ 6,295 . December 2022 Financing In December 2022, the Company issued 126,815 shares of its common stock at a price of $ 5.52 per share and to certain investors in lieu of common stock, pre-funded warrants to purchase 6,213,776 shares of common stock at a price of $ 5.51999 per pre-funded warrant. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $ 0.00001 per share exercise price of such pre-funded warrant. Aggregate net proceeds were $ 32,562 after deducting underwriting discounts and commissions and offering expens es. As of December 31, 2024, 6,213,775 pre-funded warrants had been exercised and no warrants remain outstanding. The pre-funded warrants were classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company’s common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return. At-the-Market Offering F- 22 On March 21, 2024, the Company filed an automatic shelf registration statement (S-3ASR) in relation to the registration of common stock, preferred stock, debt securities, warrants and/or units of any combination thereof for the purposes of selling, from time to time, the Company’s common stock, debt securities or other equity securities in one or more offerings. This S-3ASR became effective immediately. We intend to convert the S-3ASR to S-3 by post-effective amendments in connection with the filing of this Annual Report. The Company has a Sales Agreement with Cowen and Company, LLC (Cowen) to provide for the offering, issuance and sale of up to an aggregate amount of $ 200.0 million of common stock from time to time in “at-the-market” offerings (2024 ATM Program) pursuant to its S-3ASR, and subject to the limitations thereof. In December 2024, the Company sold 1,225,000 shares pursuant to the 2024 ATM Program for net proceeds of $ 5,129 , after deducting commissions of $ 105 . The Company previously had a Sales Agreement with Cowen to provide for the offering, issuance and sale of up to an aggregate amount of $ 100.0 million of common stock from time to time in “at-the-market” offerings (2023 ATM Program) pursuant to its shelf registration statement on Form S-3 (File No. 333-270599), which was declared effective April 26, 2023. During the year ended December 31, 2023, the Company sold 4,760,899 shares pursuant to the 2023 ATM Program for net proceeds of $ 91,740 , after deducting commissions of $ 2,352 . In the first quarter of 2024, the Company sold 258,070 additional shares, completing the 2023 ATM Program for net proceeds of $ 5,746 , after deducting commissions of $ 147 . 2018 Stock Option and Grant Plan In September 2018, the Company adopted the 2018 stock option and grant plan (the 2018 Plan), which provided for the Company to sell or issue common stock, or other stock-based awards, to employees, members of the board of directors and consultants of the Company. The Company generally granted stock-based awards with service conditions only (service-based awards), although there was one grant with performance conditions. As of December 31, 2020, there are no unvested options with performance conditions. Stock options granted under the 2018 Plan generally vest over three to four years . There were 1,959,411 options granted under the 2018 Plan prior to the Company’s IPO in October 2019. No further grants may be made under the 2018 Plan subsequent to the IPO. 2019 Stock Option and Incentive Plan The 2019 Stock Option and Incentive Plan (2019 Plan) was approved by the Company’s board of directors on October 14, 2019, and became effective on October 23, 2019. The 2019 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, directors and consultants. The number of shares initially reserved for issuance under the 2019 Plan was 2,342,288 , which will be increased each January 1 thereafter by 4 % of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s board of directors or compensation committee of the board of directors. On June 1, 2023, at the 2023 Annual Meeting of Stockholders of the Company, the stockholders of the Company approved Amendment No. 1 to the 2019 Plan, increasing the number of shares of common stock reserved for issuance under the 2019 Plan by 3,000,000 shares. On January 1, 2025, the total number of shares under the 2019 Plan was increased by 2,029,724 shares pursuant to the 2019 Plan Evergreen Provision. As of December 31, 2024, there were 1,379,305 shares remaining available for issuance under the 2019 Plan. A summary of the stock option activity is presented below: F- 23 Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding as of January 1, 2024 8,141,035 $ 8.28 7.6 $ 117,384 Granted 3,476,700 16.13 Exercised ( 210,695 ) 6.79 2,889 Forfeited/Cancelled ( 175,892 ) 15.04 Outstanding as of December 31, 2024 11,231,148 $ 10.63 7.4 $ 989 Options Exercisable at December 31, 2024 5,642,705 $ 7.92 6.1 $ 966 The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock. The weighted average grant-date fair value of stock options granted during the year ended December 31, 2024 and 2023 was $ 13.44 and $ 9.51 , respectively. The fair value of each award is estimated using Black-Scholes based on the following assumptions: Year Ended December 31, 2024 2023 Risk-free interest rate 3.43 %— 4.60 % 3.38 %— 4.68 % Expected term 5.5 years— 6.2 years 5.5 years— 6.1 years Expected volatility 106 %— 111 % 105 %— 107 % Expected dividend yield 0 % 0 % Black-Scholes requires the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include: Expected term —The expected term represents the period that stock-based awards are expected to be outstanding. The expected term for option grants is determined using the simplified method, which is the midpoint between the vesting period and the contractual term of the option. Expected volatility —As a privately held company prior to the Company’s IPO in October 2019, the Company has limited trading history for its common stock and, as such, the expected volatility is estimated based on a weighted average volatility for the Company's stock price and comparable publicly traded biotechnology companies over a period equal to the expected term of the stock-based awards. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Risk-free interest rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of a stock-based award. Expected dividend —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. Stock-based Compensation The Company has recorded stock-based compensation in the accompanying statements of operations as follows: Year Ended December 31, 2024 2023 Research and development $ 10,163 $ 5,520 General and administrative 9,302 5,823 Total $ 19,465 $ 11,343 F- 24 As of December 31, 2024, there was $ 51,239 of unrecognized compensation cost related to unvested option awards, which is expected to be recognized over a weighted-average period of 2.8 years. 2019 Employee Stock Purchase Plan The 2019 Employee Stock Purchase Plan (2019 ESPP) was approved by the Company’s board of directors on October 14, 2019, and became effective on October 23, 2019. A total of 234,229 shares of common stock were initially reserved for issuance under the 2019 ESPP, and such number of shares will be increased each January 1 thereafter through January 1, 2029 by the least of (i) 234,229 shares of common stock, (ii) 1 % of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or (iii) such lesser number of shares determined by the 2019 ESPP’s administrator. There was no increase to the total number of shares available under the 2019 ESPP on January 1, 2024, 2023 or 2022, respectively. As of December 31, 2024, there were 314,259 shares remaining available for issuance under the 2019 ESPP. Employee contributions are made through payroll deductions of up to 15 % of eligible compensation over the offering period. A participant may not accrue rights to purchase more than $ 25 worth of the Company’s common stock for each calendar year in which such right is outstanding. At the end of each offering period, shares of the Company’s common stock may be purchased at 85 % of the lesser of the Company’s common stock on (i) the first trading day of the relevant offering period and (ii) the last trading day of the relevant offering period. Each offering period will be six months in duration and will commence on each December 1 and June 1. 11. Income Taxes The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2024 2023 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % State and local taxes, net of federal benefit 7.7 7.6 Research and development credit, net 5.3 6.4 Non-deductible items and other ( 1.1 ) ( 0.5 ) Change in state and local tax rate — ( 0.7 ) Change in valuation allowance ( 32.9 ) ( 33.8 ) Total 0.0 % 0.0 % Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s deferred tax assets and liabilities consisted of the following: December 31, 2024 2023 Deferred tax assets: Federal, state and local net operating loss carryforwards $ 44,369 $ 34,534 Capitalized research and development costs 36,646 19,830 Research and development tax credits 16,296 10,192 Stock-based compensation deductions 9,919 6,066 License fee deductions 221 240 Operating lease liabilities 4,607 1,482 Accrued expenses 2,603 1,665 Gross deferred tax assets 114,661 74,009 Less: valuation allowance ( 110,723 ) ( 72,560 ) Total deferred tax assets 3,938 1,449 Deferred tax liabilities: Operating lease right-of-use assets ( 3,938 ) ( 1,449 ) Net deferred tax assets $ — $ — F- 25 The Company increased its valuation allowance by $ 38,163 for the year ended December 31, 2024 in order to maintain a full valuation allowance against its deferred tax assets. Based on the Company’s history of losses, the Company recorded a full valuation allowance against its deferred tax assets as of December 31, 2024. The Company intends to maintain a valuation allowance until sufficient positive evidence exists to support a reversal of the allowance. As of December 31, 2024, the Company had federal, state and local net operating loss carryforwards of $ 157,448 , $ 181,362 and $ 88,701 , respectively; $ 157,198 of the federal net operating losses do not expire, and the remaining $ 250 expire in 2037 . The state net operating losses begin to expire in 2037 . The local net operating losses begin to expire in 2042 . As of December 31, 2024, the Company had federal and state research and development tax credit carryforwards of $ 15,684 and $ 612 , respectively, which begin to expire in 2038 and 2036 , respectively. Under the provisions of Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the IRC), these net operating losses, credit carryforwards and other tax attributes may be subject to limitation based on previous significant changes in ownership and upon future significant changes in ownership of the Company, as defined by the IRC. The Company files income tax returns in the U.S. federal jurisdiction as well as in Pennsylvania and Philadelphia. The tax years 2023, 2022 and 2021 remain open to examination by the jurisdictions where the Company is subject to tax. The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50 % likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. As of December 31, 2024, the Company had no unrecognized income tax benefits that would affect the Company’s effective tax rate if recognized. F- 26 12. Net Loss Per Share The Company calculates basic and diluted net loss per share in conformity with the two-class method required for participating securities. For the year ended December 31, 2023, the Company had voting and non-voting common stock outstanding. In May 2024, 1,444,295 shares of non-voting common stock was converted to voting common stock and as of December 31, 2024, no shares of non-voting common stock remain outstanding. Since the rights of the voting and non-voting common stock are identical, except with respect to voting, the undistributed losses of the Company have been allocated on a proportionate basis to the two classes. Basic net loss per share of common stock is computed by dividing the net loss per share of common stock by the weighted average number of shares of common stock outstanding for the period. The weighted average shares of common stock outstanding as of December 31, 2023 included outstanding pre-funded warrants to purchase up to an aggregate of 1,168,054 shares of common stock. No pre-funded warrants remain outstanding as of December 31, 2024. Diluted net loss per share is calculated using the if-converted method, which assumes conversion of all non-voting common stock to voting common stock. Year ended December 31, 2024 Voting common stock Non-voting common stock Basic net loss per share: Numerator Allocation of undistributed losses $ ( 114,728 ) $ ( 1,136 ) Denominator Weighted average number of shares used in basic per share computation 49,038,726 485,378 Net loss per share, basic $ ( 2.34 ) $ ( 2.34 ) Diluted net loss per share: Numerator Allocation of undistributed losses for basic computation $ ( 114,728 ) $ ( 1,136 ) Reallocation of undistributed losses as a result of conversion of non-voting to voting common shares ( 1,136 ) — Allocation of undistributed losses $ ( 115,864 ) $ ( 1,136 ) Denominator Weighted average number of shares used in basic per share computation 49,038,726 485,378 Add: conversion of non-voting to voting common shares outstanding 485,378 — Weighted average number of shares used in diluted per share computation 49,524,104 485,378 Net loss per share, diluted $ ( 2.34 ) $ ( 2.34 ) F- 27 Year ended December 31, 2023 Voting common stock Non-voting common stock Basic net loss per share: Numerator Allocation of undistributed losses $ ( 64,776 ) $ ( 2,899 ) Denominator Weighted average number of shares used in basic per share computation 39,192,445 1,753,505 Net loss per share, basic $ ( 1.65 ) $ ( 1.65 ) Diluted net loss per share: Numerator Allocation of undistributed losses for basic computation $ ( 64,776 ) $ ( 2,899 ) Reallocation of undistributed losses as a result of conversion of non-voting to voting common shares ( 2,899 ) — Allocation of undistributed losses $ ( 67,675 ) $ ( 2,899 ) Denominator Weighted average number of shares used in basic per share computation 39,192,445 1,753,505 Add: conversion of non-voting to voting common shares outstanding 1,753,505 — Weighted average number of shares used in diluted per share computation 40,945,950 1,753,505 Net loss per share, diluted $ ( 1.65 ) $ ( 1.65 ) The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive: As of December 31, 2024 2023 Stock options to purchase common stock 11,231,148 8,141,035 11,231,148 8,141,035 F- 28 13. 401(k) Savings Plan The Company maintains a defined-contribution savings plan under Section 401(k) of the IRC, or the 401(k) Plan. The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis. Effective January 1, 2020, the Plan provided for matching contributions on a portion of participant contributions pursuant to the 401(k) Savings Plan’s matching formula, up to 4 % of eligible compensation. All matching contributions and participant contributions vest immediately. Contributions totaled $ 894 and $ 521 for the years ended December 31, 2024 and 2023, respectively, and have been recorded in the statements of operations. F- 29 EXHIBIT INDEX Exhibit Number Description 3.1 Third Amended and Restated Certificate of Incorporation of the Registrant, as currently in effect (incorporated by reference to Exhibit 3.1 of the Registrant’s Current Report on Form 8-K (File No. 001-39103) filed on October 30, 2019) 3.2 Amended and Restated Bylaws of the Registrant, as currently in effect (incorporated by reference to Exhibit 3.2 of the Registrant’s Current Report on Form 8-K (File No. 001-39103) filed on October 30, 2019) 3.3 Amendment No. 1 to the Amended and Restated Bylaws of the Registrant (incorporated by reference to Exhibit 3.3 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed with the SEC on May 12, 2022) 4.1 Specimen Common Stock Certificate (incorporated by reference to Exhibit 4.1 of the Registrant’s Registration Statement on Form S-1 (File No. 333-234017) filed on October 16, 2019 ) 4.2 Description of Securities (incorporated by reference to Exhibit 4.3 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 21, 2024) 4.3 Form of Pre-Funded Warrant (incorporated by reference to Exhibit 4.1 of the Registrant's Current Report on Form 8-K (File No. 001-39103) filed with the SEC on December 12, 2022 10.1# 2018 Stock Option and Grant Plan, as amended, and form of award agreements thereunder (incorporated by reference to Exhibit 10.1 of the Registrant’s Registration Statement on Form S-1 (File No. 333-234017) filed on September 30, 2019) 10.2# 2019 Stock Option and Incentive Plan, and form of award agreements thereunder. (incorporated by reference to Exhibit 10.2 of the Registrant’s Registration Statement on Form S-1/A (File No. 333-234017) filed on October 16, 2019) 10.3# Amendment No. 1 to the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed on June 1, 2023) 10.4# 2019 Employee Stock Purchase Plan. (incorporated by reference to Exhibit 10.3 of the Registrant’s Registration Statement on Form S-1/A (File No. 333-234017) filed on October 16, 2019) 10.5# Senior Executive Cash Incentive Bonus Plan (incorporated by reference to Exhibit 10.4 of the Registrant’s Quarterly Report on Form 10-Q filed on December 5, 2019) 10.6# Form of Indemnification Agreement between the Registrant and each of its directors (incorporated by reference to Exhibit 10.5 of the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.7# Form of Indemnification Agreement between the Registrant and each of its executive officers (incorporated by reference to Exhibit 10.4 of the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.8+ Amended and Restated License Agreement, dated as of July 23, 2019, among the Registrant, the Trustees of the University of Pennsylvania and the Children’s Hospital of Philadelphia (incorporated by reference to Exhibit 10.6 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 135 10.9+ Master Translational Research Services Agreement, dated as of October 2018, between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.9 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.10+ CAROT Master Services Addendum to Master Translational Research Services Agreement, dated as of February 4, 2019, between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.10 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.11+ CVPF Master Services Addendum to Master Translational Research Services Agreement, dated as of October 22, 2018, between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.11 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.12 Lease, dated as of February 11, 2019, between the Registrant and Brandywine Cira, L.P. (incorporated by reference to Exhibit 10.13 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.13# Employment Agreement between the Registrant and Steven Nichtberger (incorporated by reference to Exhibit 10.16 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.14# Employment Agreement between the Registrant and Anup Marda (incorporated by reference to Exhibit 10.17 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.15# Employment Agreement between the Registrant and Gwendolyn Binder (incorporated by reference to Exhibit 10.18 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.16# Employment Agreement between the Registrant and David Chang (incorporated by reference to Exhibit 10.19 to the Registrant’s Registration Statement on Form S-1, filed with the SEC on September 30, 2019) 10.17* Fourth Amended and Restated Non-Employee Director Compensation Policy 10.18+ First Amendment, dated May 27, 2020, to the Amended and Restated License Agreement, dated July 23, 2019, among the Registrant, the Trustees of the University of Pennsylvania and the Children’s Hospital of Philadelphia (incorporated by reference to Exhibit 10.2 to the Registrant’s Current Report on Form 8-K (File No. 001-39103) filed on May 28, 2020) 10.19+ Amendment to CAROT Master Services Addendum to Master Translational Research Services Agreement, dated as of May 18, 2020 between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on August 6, 2020) 10.20+ Second Amendment, dated October 19, 2021, to the First Amended and Restated License Agreement, dated May 27, 2020, among the Registrant, the Trustees of the University of Pennsylvania and the Children’s Hospital of Philadelphia (incorporated by reference to Exhibit 10.2 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 1, 2021) 10.21 First Amendment, dated February 15, 2022, to the Lease, dated as of February 11, 2019, between the Registrant and Brandywine Cira, L.P. (incorporated by reference to Exhibit 10.26 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 17, 2022) 10.22# Form of Employment Agreement (incorporated by reference to Exhibit 10.28 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 17, 2022) 136 10.23+ Option Agreement, dated December 23, 2021, by and between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.30 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 17, 2022) 10.24+ Licence and Supply Agreement, dated December 30, 2021, by and between the Registrant and Oxford Biomedica (UK) Limited (incorporated by reference to Exhibit 10.31 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 17, 2022) 10.25+ First Amendment to the Licence and Supply Agreement, dated as of May 2, 2023, between the Registrant and Oxford Biomedica (UK) Limited (incorporated by reference to Exhibit 10.2 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on August 10, 2023) 10.26+ Second Amendment to the Licence and Supply Agreement, dated as of August 18, 2023, between the Registrant and Oxford Biomedica (UK) Limited (incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 9, 2023) 10.27+ Exclusive License Agreement, dated October 7, 2022, by and between the Registrant and Nanjing IASO Biotherapeutics Co., LTD.(incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 10, 2022 ) 10.28+ Development, Manufacturing, and Testing Services Agreement, dated January 11, 2021, between the Registrant and WuXi Advanced Therapies Inc. (incorporated by reference to Exhibit 10.34 to the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed on March 16, 2023) 10.29+ Master Translational Research Services Agreement, dated as of February 9, 2023, between the Registrant and the Trustees of the University of Pennsylvania (incorporated by reference to Exhibit 10.1 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on May 11, 2023) 10.30+ Third Amendment to the Licence and Supply Agreement, dated as of February 21, 2024, between the Registrant and Oxford Biomedica (UK) Limited (incorporated by reference to Exhibit 10.1 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on May 15, 2024) 10.31+ Fourth Amendment to the Licence and Supply Agreement, dated as of June 24, 2024, between the Registrant and Oxford Biomedica (UK) Limited (incorporated by reference to Exhibit 10.1 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on August 8, 2024) 10.32+ Services Agreement, dated as of February 1, 2019, between the Registrant and CIC Innovation Communities, LLC (incorporated by reference to Exhibit 10.1 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 14, 2024) 10.33+ Amendment to the Services Agreement, dated as of December 1, 2021, between the Registrant and CIC Innovation Communities, LLC (incorporated by reference to Exhibit 10.2 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 14, 2024) 10.34+ Amendment to the Services Agreement, dated as of September 30, 2024, between the Registrant and CIC Innovation Communities, LLC (incorporated by reference to Exhibit 10.3 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 14, 2024) 10.35+ Second Amendment, dated September 24, 2024, to the Lease, dated as of February 11, 2019, between the Registrant and Brandywine Cira, L.P., as amended. (incorporated by reference to Exhibit 10.4 to the Registrant's Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 14, 2024) 19.1* Insider Trading Policy 21.1* List of Subsidiaries of the Registrant 137 23.1* Consent of Ernst & Young, independent registered public accounting firm 31.1* Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended 31.2* Certification of Principal Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended 32.1** Certification of Principal Executive Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to 18 U.S.C. Section 1350, as adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 32.2** Certification of Principal Financial Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to 18 U.S.C. Section 1350, as adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 99.7 Cabaletta Bio, Inc.'s Compensation Recovery Policy (incorporated by reference to Exhibit 99.7 to the Registrant's Annual Report on Form 10-K (File No. 001-39103) filed on March 21, 2024) 101.INS* Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document 101.SCH* Inline XBRL Taxonomy Extension Schema Document 101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase Document 101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase Document 101.LAB* Inline XBRL Taxonomy Extension Label Linkbase Document 101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase Document 104* Cover Page Interactive Data File (formatted as Inline XBRL with applicable taxonomy extension information contained in Exhibits 101*) # Management Contract or compensatory plan or arrangement. + Portions of this exhibit (indicated by asterisks) have been omitted pursuant to Item 601(b)(10) of Regulation S-K. * Filed herewith. ** The certifications furnished in Exhibit 32.1 and 32.2 hereto are deemed to accompany this Annual Report on Form 10-K and will not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended. Such certifications will not be deemed to be incorporated by reference into any filings under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, except to the extent that the Registrant specifically incorporates it by reference. 138 SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this Form 10-K to be signed on its behalf by the undersigned, thereunto duly authorized . Cabaletta Bio, Inc. Date: March 31, 2025 By: /s/ Steven Nichtberger Steven Nichtberger, M.D. Chief Executive Officer and President Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Annual Report on Form 10-K has been signed below by the following persons on behalf of the Registrant in the capacities and on the dates indicated. Name Title Date /s/ Steven Nichtberger Director, Chief Executive Officer and President March 31, 2025 Steven Nichtberger, M.D. (Principal Executive Officer) /s/ Anup Marda Chief Financial Officer March 31, 2025 Anup Marda (Principal Financial and Accounting Officer) /s/ Catherine Bollard Director March 31, 2025 Catherine Bollard, M.D. /s/ Scott Brun Director March 31, 2025 Scott Brun, M.D. /s/ Richard Henriques Director March 31, 2025 Richard Henriques /s/ Mark Simon Director March 31, 2025 Mark Simon /s/ Shawn Tomasello Director March 31, 2025 Shawn Tomasello 139