CABA / Cabaletta Bio, Inc. - Pengajuan SECLaporan Tahunan, Pernyataan Proksi

Corporate Presentation September 2025

Corporate Presentation September 2025 Disclaimer This presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document distributed at or in connection with the presentation (collectively, the “Presentation”) has been prepared by Cabaletta Bio, Inc.

FORM 8-K Item 7.01 Regulation FD Disclosure.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 03, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission

Cabaletta Bio Reports Second Quarter 2025 Financial Results and Provides Business Update – Registrational cohort enrollment in RESET-Myositis™ trial on track to start in 2H25 with anticipated 2027 BLA submission for rese-cel in myositis – – Five dise

Exhibit 99.1 Cabaletta Bio Reports Second Quarter 2025 Financial Results and Provides Business Update – Registrational cohort enrollment in RESET-Myositis™ trial on track to start in 2H25 with anticipated 2027 BLA submission for rese-cel in myositis – – Five disease-specific cohorts fully enrolled in the RESET™ clinical development program from over 70 clinical sites as of July 31, 2025, with expa

Sales Agreement, dated as of August 7, 2025 between the Registrant and TD Securities (USA) LLC

EX-1.2 Exhibit 1.2 CABALETTA BIO, INC. $150,000,000 COMMON STOCK SALES AGREEMENT August 7, 2025 TD Securities (USA) LLC 1 Vanderbilt Avenue New York, NY 10017 Ladies and Gentlemen: Cabaletta Bio, Inc. (the “Company”), confirms its agreement (this “Agreement”) with TD Securities (USA) LLC (“TD Cowen”), as follows: 1. Issuance and Sale of Shares. The Company agrees that, from time to time during the

Form of Subordinated Indenture between Registrant and one or more trustees to be named

EX-4.5 Exhibit 4.5 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Subordinated Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1 Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4 Section 2.01 Designation and Terms of Securities 4 Section 2.02 Form of Securities and Trustee’s C

Form of Senior Indenture between Registrant and one or more trustees to be named

EX-4.4 Exhibit 4.4 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Senior Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1   Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4   Section 2.01 Designation and Terms of Securities 4   Section 2.02 Form of Securities and Trustee’s C

As filed with the Securities and Exchange Commission on August 7, 2025

S-3 Table of Contents As filed with the Securities and Exchange Commission on August 7, 2025 Registration No.

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 07, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission Fil

Development and Manufacturing Services Agreement, dated as of December 19, 2024, between the Registrant and Lonza Houston Inc.

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. Development and Manufacturing Services Agreement (the “Agreement”) by and between Lonza Houston Inc. 14905 Kirby

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Cabaletta Bio, Inc.

Current Report

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 11, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission File

39,200,000 Shares of Common Stock Pre-funded Warrants to Purchase up to 10,800,000 Shares of Common Stock Warrants to Purchase up to 50,000,000 Shares of Common Stock (or Pre-Funded Warrants)

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-278126 PROSPECTUS SUPPLEMENT (To prospectus dated March 31, 2025) 39,200,000 Shares of Common Stock Pre-funded Warrants to Purchase up to 10,800,000 Shares of Common Stock Warrants to Purchase up to 50,000,000 Shares of Common Stock (or Pre-Funded Warrants) We are selling 39,200,000 shares of our common stock, par value $0.000

Underwriting Agreement, dated June 11, 2025, between Cabaletta Bio, Inc. and Jefferies LLC, TD Securities (USA) LLC and Cantor Fitzgerald & Co. as representatives of the several underwriters named therein.

Exhibit 1.1 39,200,000 Shares of Common Stock Pre-Funded Warrants to purchase 10,800,000 Shares Warrants to Purchase 50,000,000 Shares of Common Stock (or Pre-Funded Warrants in lieu thereof) CABALETTA BIO, INC. UNDERWRITING AGREEMENT June 11, 2025 JEFFERIES LLC TD SECURITIES (USA) LLC CANTOR FITZGERALD & CO. As Representatives of the several Underwriters c/o JEFFERIES LLC 520 Madison Avenue New Y

Form of Pre-Funded Warrant.

Exhibit 4.1 Form of Pre-Funded Warrant CABALETTA BIO, INC. WARRANT TO PURCHASE COMMON STOCK Number of Shares: [] (subject to adjustment) Warrant No. [] Original Issue Date: June [], 2025 Cabaletta Bio, Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [] or its registered assigns (

Cabaletta Bio Announces Pricing of Public Offering of Securities

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces Pricing of Public Offering of Securities PHILADELPHIA, June 11, 2025 — Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies designed specifically for patients with autoimmune diseases, announced today the pricing of an unde

Form of Common Stock Warrant.

Exhibit 4.2 CABALETTA BIO, INC. WARRANT TO PURCHASE COMMON STOCK OR PRE-FUNDED WARRANTS Number of Shares: [] (subject to adjustment) Warrant No. [] Original Issue Date: June [], 2025 Cabaletta Bio, Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [] or its registered assigns (the

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 11, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 11, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File N

Subject to Completion Preliminary Prospectus Supplement dated June 11, 2025

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-278126 The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been declared effective by the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell

Cabaletta Bio Announces New Rese-cel Safety and Efficacy Data in Patients with Myositis, Lupus and Scleroderma to Be Presented at the EULAR 2025 Congress – 7 of 8 myositis patients achieved clinically meaningful TIS responses after discontinuation of

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces New Rese-cel Safety and Efficacy Data in Patients with Myositis, Lupus and Scleroderma to Be Presented at the EULAR 2025 Congress – 7 of 8 myositis patients achieved clinically meaningful TIS responses after discontinuation of all immunomodulators, while off or actively tapering steroids; responses were sustained throughout the follow-up period in all r

Disclaimer This presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document distr

EX-99.2 Corporate Presentation JUNE 2025 Exhibit 99.2 Disclaimer This presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document distributed at or in connection with the presentation (collectively, the “Presentation”) has been pre

Certificate of Amendment to the Third Amended and Restated Certificate of Incorporation

EX-3.1 Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE THIRD AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF CABALETTA BIO, INC. Cabaletta Bio, Inc. (the “Corporation”), a corporation duly organized and existing under the laws of the State of Delaware pursuant to Section 242 of the General Corporation Law of the State of Delaware (the “DGCL”), hereby certifies as follows: 1. The Third Amended and

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 9, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 9, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 15, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission File N

Cabaletta Bio Announces 2027 Rese-cel BLA Submission Anticipated in Myositis Following Recent FDA Alignment on Registrational Cohorts – Two subtype specific cohorts with ~15 patients each added to the ongoing RESET-MyositisTM trial – – RMAT designati

Exhibit 99.1 Cabaletta Bio Announces 2027 Rese-cel BLA Submission Anticipated in Myositis Following Recent FDA Alignment on Registrational Cohorts – Two subtype specific cohorts with ~15 patients each added to the ongoing RESET-MyositisTM trial – – RMAT designation granted for rese-cel in myositis, which is a disabling, multi-system autoimmune disease affecting approximately 80,000 U.S. patients w

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 15, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission File N

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitte

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 31, 2025 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission File

As filed with the Securities and Exchange Commission on March 31, 2025

As filed with the Securities and Exchange Commission on March 31, 2025 Registration No.

Power of Attorney (included on signature pages hereto)

Table of Contents As filed with the Securities and Exchange Commission on March 31, 2025 Registration No.

Fourth Amended and Restated Non-Employee Director Compensation Policy

Exhibit 10.17 CABALETTA BIO, INC. FOURTH AMENDED AND RESTATED NON-EMPLOYEE DIRECTOR COMPENSATION POLICY The purpose of this Third Amended and Restated Non-Employee Director Compensation Policy of Cabaletta Bio, Inc. (the “Company”), is to provide a total compensation package that enables the Company to attract and retain, on a long-term basis, high-caliber directors who are not employees or office

Cabaletta Bio Reports Fourth Quarter and Full Year 2024 Financial Results and Provides Business Update – FDA meeting to align on myositis registrational trial designs for rese-cel in 1H25 on track – – Enrolling approximately one patient per week acro

Exhibit 99.1 Cabaletta Bio Reports Fourth Quarter and Full Year 2024 Financial Results and Provides Business Update – FDA meeting to align on myositis registrational trial designs for rese-cel in 1H25 on track – – Enrolling approximately one patient per week across the RESET™ clinical development program since ACR Convergence presentation in November 2024 with 33 patients enrolled across 56 active

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Cabaletta Bio, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-39103 CABALETTA BIO,

List of Subsidiaries of the Registrant

Exhibit 21.1 Cabaletta Bio, Inc. The following is a list of subsidiaries of Cabaletta Bio, Inc. as of December 31, 2024. SUBSIDIARY STATE OR OTHER JURISDICTION OF INCORPORATION OR ORGANIZATION Cabaletta Bio, Inc. Delaware Cabaletta Bio GmbH Switzerland Cabaletta Bio (Germany) GmbH Germany

As filed with the Securities and Exchange Commission on March 31, 2025

Table of Contents As filed with the Securities and Exchange Commission on March 31, 2025 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Cabaletta Bio, Inc.

Insider Trading Policy

Exhibit 19.1 CABALETTA BIO, INC. STATEMENT OF COMPANY POLICY ON INSIDER TRADING AND DISCLOSURE This memorandum sets forth the policy of Cabaletta Bio, Inc. and its subsidiaries (collectively, the “Company”) regarding trading in the Company’s securities as described below and the disclosure of information concerning the Company. This Insider Trading Policy (the “Insider Trading Policy”) is designed

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 February 18, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 February 18, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fi

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation FEBRUary 2025 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Pr

Cabaletta Bio Announces Updated Clinical Data Demonstrating Deepening Clinical Responses across Multiple Indications with Rese-cel at February Scientific – Clinical efficacy continued to deepen over time with three SLE patients in DORIS remission, th

EX-99.2 Exhibit 99.2 Cabaletta Bio Announces Updated Clinical Data Demonstrating Deepening Clinical Responses across Multiple Indications with Rese-cel at February Scientific Meetings – Clinical efficacy continued to deepen over time with three SLE patients in DORIS remission, the first LN patient achieving complete renal response, and the first dermatomyositis patient maintaining a major TIS impr

Regulation FD Disclosure

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No. 1) CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 February 18, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorpora

Cabaletta Bio Announces Updated Clinical Data Demonstrating Deepening Clinical Responses across Multiple Indications with Rese-cel at February Scientific – Clinical efficacy continued to deepen over time with three SLE patients in DORIS remission, th

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces Updated Clinical Data Demonstrating Deepening Clinical Responses across Multiple Indications with Rese-cel at February Scientific Meetings – Clinical efficacy continued to deepen over time with three SLE patients in DORIS remission, the first LN patient achieving complete renal response, and the first dermatomyositis patient maintaining a major TIS impr

Cabaletta Bio Outlines Strategic Priorities and Anticipated Key Milestones for 2025 – Company plans to meet with the FDA to align on registrational trial designs in 1H25 based on emerging clinical profile of resecabtagene autoleucel (rese-cel, former

Exhibit 99.2 Cabaletta Bio Outlines Strategic Priorities and Anticipated Key Milestones for 2025 – Company plans to meet with the FDA to align on registrational trial designs in 1H25 based on emerging clinical profile of resecabtagene autoleucel (rese-cel, formerly referred to as CABA-201) and increased pace of enrollment with 44 active clinical trial sites – – Favorable safety profile observed ac

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 January 13, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, IN

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 January 13, 2025 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

Corporate Presentation JANUARY 2025 © 2025 Cabaletta Bio. All rights reserved. 

Exhibit 99.1 Corporate Presentation JANUARY 2025 © 2025 Cabaletta Bio. All rights reserved.  Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the

CABA / Cabaletta Bio, Inc. / ALGER ASSOCIATES INC - CABALETTA BIO, INC. Passive Investment

Cabaletta Bio, Inc. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 3)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) November 30, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursua

CABA / Cabaletta Bio, Inc. / PRUDENTIAL FINANCIAL INC Passive Investment

SC 13G/A 1 caba2.htm DOCUMENT TYPE SC 13G/A TEXT SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 Amendment # 1 Name of Issuer: CABALETTA BIO INC Title of Class of Securities: Common Stock CUSIP Number: 12674W109 1) NAME AND I.R.S. IDENTIFICATION NO. OF REPORTING PERSON Prudential Financial, Inc. 22-3703799 2.) MEMBER OF A GROUP: (a)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 18, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 18, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fi

Cabaletta Bio Presents Positive Clinical Safety and Efficacy Data on CABA-201 at ACR Convergence 2024 – CABA-201 safety profile suggests favorable risk-benefit with no CRS or ICANS in the majority of patients; low-grade CRS in three of eight patients

EX-99.2 Exhibit 99.2   Cabaletta Bio Presents Positive Clinical Safety and Efficacy Data on CABA-201 at ACR Convergence 2024 – CABA-201 safety profile suggests favorable risk-benefit with no CRS or ICANS in the majority of patients; low-grade CRS in three of eight patients and one previously reported ICANS event – – Compelling clinical responses observed in lupus and myositis patients with up to s

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Exhibit 99.1 CABA-201 Clinical and Translational Data from the RESET Phase 1/2 Trials NOVEMBER 2024 © 2024 Cabaletta Bio. All rights reserved. Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docu

Poster presentation from Cabaletta Bio, Inc., dated November 16, 2024

Exhibit 99.3 Correlative Studies of CABA-201, a Fully Human, Autologous 4-1BB Anti-CD19 CAR T Cell Therapy in #0324 Patients with Immune-Mediated Necrotizing Myopathy and Systemic Lupus Erythematosus from the Presented at the TM TM ACR Convergence 2024 RESET-Myositis and RESET-SLE Clinical Trials 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 Nov 14-19, 2024 Daniel Nunez , Jenell Volkov , Jason Stadanlick , Za

Disclosures Author Disclosures David J. Chang Employee: Cabaletta Bio Saira Sheikh Consultant: AstraZeneca; Biogen; Cabaletta Bio; GSK Tahseen Mozaffar Advisor or Review Panel Member, Grant/Research Support: Amicus; AnnJi; Argenx; Astellas Gene Thera

EX-99.4 Safety and efficacy of CABA-201, a fully human, autologous 4-1BB anti-CD19 CAR T cell therapy in patients with immune-mediated necrotizing myopathy and systemic lupus erythematosus from the RESET-Myositis™ and RESET-SLE™ clinical trials Saira Sheikh1; Tahseen Mozaffar2; Vimal Derebail1; Natalie Grover1; Jonathan Hogan3; Courtney Little3; Yvonne White3; Claire Miller3; Rebecca Estremera3; J

Amendment to the Services Agreement, dated as of December 1, 2021, between the Registrant and CIC Innovation Communities, LLC

Exhibit 10.2 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. Large Lab Client Customization Agreement 12/1/21 Terms for new space and fees for Cabaletta Bio custom laboratory

Cabaletta Bio Reports Third Quarter 2024 Financial Results and Provides Business Update – Clinical data from the RESET-Myositis™ and RESET-SLE™ trials, along with initial clinical data from the RESET-SSc™ trial, to be presented this weekend in oral a

Exhibit 99.1 Cabaletta Bio Reports Third Quarter 2024 Financial Results and Provides Business Update – Clinical data from the RESET-Myositis™ and RESET-SLE™ trials, along with initial clinical data from the RESET-SSc™ trial, to be presented this weekend in oral and poster presentations at ACR Convergence 2024 – – 16 patients enrolled with 10 patients dosed as of November 12 across the RESET™ clini

CABA / Cabaletta Bio, Inc. / Venrock Healthcare Capital Partners III, L.P. - SC 13G/A Passive Investment

SC 13G/A 1 tm2428137d4sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of this Statement)

Amendment to the Services Agreement, dated as of September 30, 2024, between the Registrant and CIC Innovation Communities, LLC

Exhibit 10.3 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. SERVICE AGREEMENT Amendment AMENDMENT TO SERVICE AGREEMENT CIC and Client hereby agree to supplement the Service

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 14, 2024 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission F

CABA / Cabaletta Bio, Inc. / ALGER ASSOCIATES INC - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 d891197dsc13ga.htm CABALETTA BIO, INC. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropriate b

Services Agreement, dated as of February 1, 2019, between the Registrant and CIC Innovation Communities, LLC

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. SERVICE AGREEMENT The licensee(s) identified on the signature block of this agreement (the “Licensee”) and CIC he

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

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.

Exhibit 10.4 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. SECOND AMENDMENT TO LEASE THIS SECOND AMENDMENT TO LEASE (“Amendment”) is made and entered into as of October 1,

CABA / Cabaletta Bio, Inc. / Adage Capital Management, L.P. - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 p24-3076sc13ga.htm CABALETTA BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 5)*, ** Cabaletta Bio, Inc. (Name of Issuer) Voting Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of This State

CABA / Cabaletta Bio, Inc. / STATE STREET CORP Passive Investment

SC 13G/A 1 CabalettaBioInc.htm SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* CABALETTA BIO INC (Name of Issuer) COMMON STOCK (Title of Class of Securities) 12674W109 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant to

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation OCTOBER 2024 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Pre

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 October 7, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 October 7, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 30, 2024 CABALETTA BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-39103 82-1685768 (State or Other Jurisdiction of Incorporation) (Commission

CABA / Cabaletta Bio, Inc. / Bain Capital Life Sciences Opportunities III, LP - SC 13G Passive Investment

SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.

Fourth Amendment to the Licence and Supply Agreement, dated as of June 24, 2024, between the Registrant and Oxford Biomedica (UK) Limited

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. Fourth Amendment Agreement This fourth amendment agreement (“Agreement”) is dated the date of the last signature

Cabaletta Bio Reports Second Quarter 2024 Financial Results and Provides Business Update – Nine patients enrolled as of August 5, 2024 across the RESET™ clinical development program, including four since EULAR in June, with 22 U.S. clinical sites now

Exhibit 99.1 Cabaletta Bio Reports Second Quarter 2024 Financial Results and Provides Business Update – Nine patients enrolled as of August 5, 2024 across the RESET™ clinical development program, including four since EULAR in June, with 22 U.S. clinical sites now enrolling – – Additional clinical data from the RESET-Myositis™ and RESET-SLE™ trials as well as initial clinical data from the RESET-SS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 8, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 8, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.2 Corporate Presentation augusT 2024 Exhibit 99.2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Pres

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

CABA-201 Initial Clinical Data from the RESET-Myositis™ & RESET-SLE™ Phase 1/2 Trials JUNE 2024 Exhibit 99.

Symposium Speakers Drs Georg Schett and Carl June are members of Cabaletta Bio’s Scientific Advisory Board. David J. Chang, MD, MPH, FACR Chief Medical Officer Cabaletta Bio Philadelphia, PA Carl H. June, MD Director of the Center for Cellular Immunoth

IMMUNE Reset: The potential of car t cell therapy to transform the treatment of patients with autoimmune disease Exhibit 99.

Regulation FD Disclosure, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 14, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File N

Cabaletta Bio Reports Positive Initial Clinical Data from Phase 1/2 RESET-Myositis™ and RESET-SLE™ Trials of CABA-201 – No CRS, ICANS, infections or serious adverse events observed in either of the first two patients through data cut-off of May 28, 2

Exhibit 99.2 Cabaletta Bio Reports Positive Initial Clinical Data from Phase 1/2 RESET-Myositis™ and RESET-SLE™ Trials of CABA-201 – No CRS, ICANS, infections or serious adverse events observed in either of the first two patients through data cut-off of May 28, 2024 – – CABA-201 exhibited anticipated profile of CAR T cell expansion and contraction with complete B cell depletion observed in both pa

Current Report

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 3, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Third Amendment to the Licence and Supply Agreement, dated as of February 21, 2024, between the Registrant and Oxford Biomedica (UK) Limited

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. Amendment Agreement This amendment agreement (“Agreement”) is dated 21st February 2024 PARTIES (1) OXFORD BIOMEDI

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 15, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 15, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.2 Exhibit 99.2 Corporate Presentation MAY 2024 © 2024 Cabaletta Bio. All rights reserved. Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with t

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Cabaletta Bio Reports First Quarter 2024 Financial Results and Provides Business Update – No CRS or ICANS of any grade observed during the 28-day DLT observation window for either of the first patients dosed with CABA-201 in the RESET-Myositis™ and R

EX-99.1 Exhibit 99.1 Cabaletta Bio Reports First Quarter 2024 Financial Results and Provides Business Update – No CRS or ICANS of any grade observed during the 28-day DLT observation window for either of the first patients dosed with CABA-201 in the RESET-Myositis™ and RESET-SLE™ trials – – Initial clinical data from each of the first patients in the RESET-Myositis and RESET-SLE trials to be prese

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitte

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Cabaletta Bio, Inc.

Cabaletta Bio, Inc.'s Compensation Recovery Policy

Exhibit 99.7 CABALETTA BIO, INC. COMPENSATION RECOVERY POLICY Cabaletta Bio, Inc., a Delaware corporation (the “Company”), has adopted a Compensation Recovery Policy (this “Policy”) as described below. 1. Overview The Policy sets forth the circumstances and procedures under which the Company shall recover Erroneously Awarded Compensation from Covered Persons (as defined below) in accordance with r

Cabaletta Bio Reports Fourth Quarter and Full Year 2023 Financial Results and Provides Business Update – First patient dosed with CABA-201 in the RESET™ (REstoring SElf-Tolerance) clinical trial program – – Initial clinical data from each of the firs

Exhibit 99.1 Cabaletta Bio Reports Fourth Quarter and Full Year 2023 Financial Results and Provides Business Update – First patient dosed with CABA-201 in the RESET™ (REstoring SElf-Tolerance) clinical trial program – – Initial clinical data from each of the first patients in the RESET-Myositis™ and RESET-SLE™ trials anticipated in 1H24; longer term follow-up on these and additional patients to be

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-39103 CABALETTA BIO,

As filed with the Securities and Exchange Commission on March 21, 2024

As filed with the Securities and Exchange Commission on March 21, 2024 Registration No.

Sales Agreement, dated as of March 21, 2024 between the Registrant and Cowen and Company, LLC

Exhibit 1.2 CABALETTA BIO, INC. $200,000,000 COMMON STOCK SALES AGREEMENT March 21, 2024 Cowen and Company, LLC 599 Lexington Avenue New York, NY 10022 Ladies and Gentlemen: Cabaletta Bio, Inc. (the “Company”), confirms its agreement (this “Agreement”) with Cowen and Company, LLC (“Cowen”), as follows: 1. Issuance and Sale of Shares. The Company agrees that, from time to time during the term of th

List of Subsidiaries of the Registrant

Exhibit 21.1 List of Subsidiaries None.

Form of Subordinated Indenture between Registrant and one or more trustees to be named

Exhibit 4.4 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Subordinated Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1 Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4 Section 2.0 Designation and Terms of Securities 4 Section 2.02 Form of Securities and Trustee’s Certifica

Form of Senior Indenture between Registrant and one or more trustees to be named (incorporated by reference to Exhibit 4.3 to the Registrant’s Registration Statement on Form S-3 (File No. 333-278126) field with the SEC on March 21, 2024)

Exhibit 4.3 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Senior Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1 Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4 Section 2.01 Designation and Terms of Securities 4 Section 2.02 Form of Securities and Trustee’s Certificate 6

Description of Securities (incorporated by reference to Exhibit 4.3 of the Registrant’s Annual Report on Form 10-K (File No. 001-39103) filed with the Securities and Exchange Commission on March 21, 2024).

Exhibit 4.3 Description of the Registrant’s Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934, as amended The following summary of the general terms and provisions of the registered capital stock of Cabaletta Bio, Inc. (“Cabaletta”, “we”, “our”) does not purport to be complete and is subject to, and qualified in its entirety by, reference to our Third Amended and

Third Amended and Restated Non-Employee Director Compensation Policy

Exhibit 10.19 CABALETTA BIO, INC. THIRD AMENDED AND RESTATED NON-EMPLOYEE DIRECTOR COMPENSATION POLICY The purpose of this Third Amended and Restated Non-Employee Director Compensation Policy of Cabaletta Bio, Inc. (the “Company”), is to provide a total compensation package that enables the Company to attract and retain, on a long-term basis, high-caliber directors who are not employees or officer

As filed with the Securities and Exchange Commission on March 21, 2024

Table of Contents As filed with the Securities and Exchange Commission on March 21, 2024 Registration No.

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3ASR (Form Type) Cabaletta Bio, Inc.

Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 21, 2024 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Cabaletta Bio Announces FDA Granted Orphan Drug Designation to CABA-201 for Treatment of Systemic Sclerosis

Exhibit 99.1 Cabaletta Bio Announces FDA Granted Orphan Drug Designation to CABA-201 for Treatment of Systemic Sclerosis PHILADELPHIA, March 20, 2024 — Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced that the U.S. Food and Drug Administrat

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2024 CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2024 CABALETTA BIO, INC. (Exact name of registrant as specified in its charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

CABA / Cabaletta Bio, Inc. / BAKER BROS. ADVISORS LP - SC 13G/A Passive Investment

SC 13G/A 1 tm242424d12sc13ga.htm SC 13G/A SCHEDULE 13G SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event which Requires Filing of this Statement) Check the appropri

CABA / Cabaletta Bio, Inc. / ALGER ASSOCIATES INC - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 d743764dsc13ga.htm CABALETTA BIO, INC. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate bo

CABA / Cabaletta Bio, Inc. / Lynx1 Capital Management LP - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 p24-0765sc13ga.htm CABALETTA BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, $0.00001 par value per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of this Statement) Check

CABA / Cabaletta Bio, Inc. / Venrock Healthcare Capital Partners III, L.P. - SC 13G/A Passive Investment

SC 13G/A 1 tm246235d4sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of this Statement) C

CABA / Cabaletta Bio, Inc. / Cormorant Asset Management, LP - AMENDMENT NO. 2 Passive Investment

SC 13G/A 1 sc13ga.htm AMENDMENT NO. 2 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designa

CABA / Cabaletta Bio, Inc. / COMMODORE CAPITAL LP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

CABA / Cabaletta Bio, Inc. / Bain Capital Life Sciences Opportunities III, LP - SC 13G/A Passive Investment

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.

CABA / Cabaletta Bio, Inc. / Nichtberger Steven - SC 13G/A Passive Investment

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to design

CABA / Cabaletta Bio, Inc. / Flynn James E Passive Investment

SC 13G/A 1 e619242sc13ga-cb.htm SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(b) (Amendment No. 1) * Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023

CABA / Cabaletta Bio, Inc. / ADAGE CAPITAL PARTNERS GP, L.L.C. - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 p24-0432sc13ga.htm CABALETTA BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 4)* Cabaletta Bio, Inc. (Name of Issuer) Voting Common Stock, $0.00001 par value per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of This Statement)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 1, 2024 CABALETTA BIO, I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 1, 2024 CABALETTA BIO, INC. (Exact name of registrant as specified in its charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fi

Cabaletta Bio Announces FDA Granted Orphan Drug Designation to CABA-201 for Treatment of Myositis

Exhibit 99.1 Cabaletta Bio Announces FDA Granted Orphan Drug Designation to CABA-201 for Treatment of Myositis PHILADELPHIA, Feb. 1, 2024 — Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced that the U.S. Food and Drug Administration (FDA) ha

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 8, 2024 CABALETTA BIO, INC. (Exact name of registrant as specified in its charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

Cabaletta Bio Receives Additional FDA Fast Track Designations for CABA-201 in Dermatomyositis and Systemic Sclerosis – Second and third FDA Fast Track Designations for CABA-201, following the systemic lupus erythematosus (SLE) and lupus nephritis (LN

Exhibit 99.2 Cabaletta Bio Receives Additional FDA Fast Track Designations for CABA-201 in Dermatomyositis and Systemic Sclerosis – Second and third FDA Fast Track Designations for CABA-201, following the systemic lupus erythematosus (SLE) and lupus nephritis (LN) designation, providing the opportunity for expedited development and review of CABA-201 for the treatment of these autoimmune diseases

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

Exhibit 99.1 Corporate Presentation JANUARY 2024 © 2024 Cabaletta Bio. All rights reserved. Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the p

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

Corporate Presentation NOVEMBER 2023 Exhibit 99.2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Presentati

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)

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. Cabaletta Bio, Inc. 2929 Arch Street, Suite 600, Philadelphia, PA 19104, USA Attention: CEO 16 Aug 2023 To whom i

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition, Completion of Acquisition or Disposition of Assets

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 9, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

Amendment No. 5, dated July 25, 2023, to the Sponsored Research Agreement, dated April 23, 2018, between the Registrant and the Trustees of the University of Pennsylvania

Exhibit 10.2 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. AMENDMENT NO. 5 TO SPONSORED RESEARCH AGREEMENT This Amendment No. 5 to the Sponsored Research Agreement (“Amendm

Cabaletta Bio Reports Third Quarter 2023 Financial Results and Provides Business Update – Initial clinical data from CABA-201 treated patients in Phase 1/2 trials for lupus and/or myositis expected in the first half of 2024, with the first lupus clin

Exhibit 99.1 Cabaletta Bio Reports Third Quarter 2023 Financial Results and Provides Business Update – Initial clinical data from CABA-201 treated patients in Phase 1/2 trials for lupus and/or myositis expected in the first half of 2024, with the first lupus clinical site actively recruiting patients – – Expanded CABA-201 clinical development program within rheumatology and into neurology with add

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Cabaletta Bio Receives FDA Clearance of CABA-201 IND Application for Treatment of Generalized Myasthenia Gravis – First cleared CD19-CAR T IND application for generalized myasthenia gravis announced in the U.S. and fourth IND clearance for CABA-201 a

Exhibit 99.1 Cabaletta Bio Receives FDA Clearance of CABA-201 IND Application for Treatment of Generalized Myasthenia Gravis – First cleared CD19-CAR T IND application for generalized myasthenia gravis announced in the U.S. and fourth IND clearance for CABA-201 across a broad range of autoimmune diseases – – Clearance expands the clinical development of CABA-201 beyond rheumatology into neurology

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 6, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, IN

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 6, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

Exhibit 99.1 Corporate Presentation OCTOBER 2023 © 2023 Cabaletta Bio. All rights reserved. Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the p

Cabaletta Bio Receives FDA Clearance of IND Application for Treatment of Systemic Sclerosis with CABA-201 – Third IND application clearance for CABA-201 within the past 6 months across a broad range of autoimmune diseases – – Phase 1/2 clinical trial

Exhibit 99.2 Cabaletta Bio Receives FDA Clearance of IND Application for Treatment of Systemic Sclerosis with CABA-201 – Third IND application clearance for CABA-201 within the past 6 months across a broad range of autoimmune diseases – – Phase 1/2 clinical trial evaluating CABA-201 in systemic sclerosis features parallel cohort design and the same starting dose as the CABA-201 INDs for lupus and

Regulation FD Disclosure, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 October 2, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation September 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “P

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 September 5, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 September 5, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fi

Cabaletta Bio and WuXi Advanced Therapies Announce Expansion of GMP Manufacturing Agreement to Include CABA-201 – Agreement expansion facilitates preparation for commercial readiness for CABA-201, enabling treatment of patients in multiple planned cl

Exhibit 99.1 Cabaletta Bio and WuXi Advanced Therapies Announce Expansion of GMP Manufacturing Agreement to Include CABA-201 – Agreement expansion facilitates preparation for commercial readiness for CABA-201, enabling treatment of patients in multiple planned clinical trials with separate parallel cohorts – – Partnership for CABA-201 builds on existing manufacturing agreement for clinical trial s

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 18, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 18, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

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)

Exhibit 10.2 Cabaletta Bio, Inc. 2929 Arch Street, Suite 600, Philadelphia, PA 19104, USA Attention: CEO 27 March 2023 To whom it may concern Amendment to Licence and Supply Agreement 1. We refer to the Licence and Supply Agreement dated 30 December 2021 entered into between Oxford Biomedica (UK) Limited and Cabaletta Bio, Inc. (the “Licence Agreement”). Unless expressly defined herein, capitalise

Filing Fee Table.

EX-FILING FEES Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Cabaletta Bio, Inc.

Cabaletta Bio Reports Second Quarter 2023 Financial Results and Provides Business Update – Received second IND application clearance for CABA-201 in myositis as well as Fast Track Designation in SLE and LN – – Strengthened balance sheet by closing $1

EX-99.1 Exhibit 99.1 Cabaletta Bio Reports Second Quarter 2023 Financial Results and Provides Business Update – Received second IND application clearance for CABA-201 in myositis as well as Fast Track Designation in SLE and LN – – Strengthened balance sheet by closing $100M public offering extending cash runway into the fourth quarter of 2025 – PHILADELPHIA, Aug. 10, 2023 – Cabaletta Bio, Inc. (Na

Second Amended and Restated Non-Employee Director Compensation Policy

Exhibit 10.3 CABALETTA BIO, INC. SECOND AMENDED AND RESTATED NON-EMPLOYEE DIRECTOR COMPENSATION POLICY The purpose of this Amended and Restated Non-Employee Director Compensation Policy of Cabaletta Bio, Inc. (the “Company”), is to provide a total compensation package that enables the Company to attract and retain, on a long-term basis, high-caliber directors who are not employees or officers of t

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

As filed with the Securities and Exchange Commission on August 10, 2023

S-8 As filed with the Securities and Exchange Commission on August 10, 2023 Registration No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 10, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 10, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

Corporate Presentation JULY 2023 Exhibit 99.2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Presentation”)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 21, 2023 CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 21, 2023 CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Cabaletta Bio Appoints Global Commercial Leader Shawn Tomasello to Board of Directors – Ms. Tomasello created and led global commercial and medical affairs functions at Kite Pharma from pre-launch through its acquisition by Gilead Sciences –

EX-99.1 Exhibit 99.1 Cabaletta Bio Appoints Global Commercial Leader Shawn Tomasello to Board of Directors – Ms. Tomasello created and led global commercial and medical affairs functions at Kite Pharma from pre-launch through its acquisition by Gilead Sciences – PHILADELPHIA, July 24, 2023 – Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launch

CABA / Cabaletta Bio Inc / Bain Capital Life Sciences Opportunities III, LP - SC 13G Passive Investment

SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.

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)

EX-10.1 Exhibit 10.1 AMENDMENT NO. 1 TO THE CABALETTA BIO, INC. 2019 STOCK OPTION AND INCENTIVE PLAN WHEREAS, Cabaletta Bio, Inc. (the “Company”) maintains the Cabaletta Bio, Inc. 2019 Stock Option and Incentive Plan (the “Plan”), which was previously adopted by the Board of Directors of the Company (the “Board”) and approved by the stockholders of the Company; WHEREAS, the Board desires to amend

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 1, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

CABA / Cabaletta Bio Inc / Flynn James E Passive Investment

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(b) (Amendment No.

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 22, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Cabaletta Bio Announces Closing of $100 Million Public Offering of Common Stock, Including Full Exercise of Option to Purchase Additional Shares

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces Closing of $100 Million Public Offering of Common Stock, Including Full Exercise of Option to Purchase Additional Shares PHILADELPHIA, May 22, 2023 — Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with au

7,250,000 Shares of Common Stock

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-270599 PROSPECTUS SUPPLEMENT (To prospectus dated April 26, 2023) 7,250,000 Shares of Common Stock We are selling 7,250,000 shares of our common stock, par value $0.00001 per share, or the common stock, in this offering pursuant to this prospectus supplement and the accompanying prospectus. Our common stock is listed on

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 17, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Underwriting Agreement, dated May 17, 2023, between the Company, Cowen and Company, LLC, Evercore Group L.L.C. and Guggenheim Securities, LLC as representatives of the several underwriters named therein.

Exhibit 1.1 CABALETTA BIO, INC. 7,250,000 Shares of Common Stock UNDERWRITING AGREEMENT May 17, 2023 COWEN AND COMPANY, LLC EVERCORE GROUP L.L.C. GUGGENHEIM SECURITIES, LLC As Representatives of the several Underwriters c/o Cowen and Company, LLC 599 Lexington Avenue New York, New York 10022 c/o Evercore Group L.L.C. 55 East 52nd Street New York, New York 10055 c/o Guggenheim Securities, LLC 330 M

Subject to Completion Preliminary Prospectus Supplement dated , 2023

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-270599 The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been declared effective by the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell

Cabaletta Bio Announces Pricing of Public Offering of Common Stock

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces Pricing of Public Offering of Common Stock PHILADELPHIA, May 17, 2023 — Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced the pricing of an underwritten public offer

Cabaletta Bio Receives FDA Clearance of IND Application for CABA-201 for Treatment of Myositis

EX-99.1 Exhibit 99.1 Cabaletta Bio Receives FDA Clearance of IND Application for CABA-201 for Treatment of Myositis — Phase 1/2 trial for CABA-201 planned to initiate in patients with myositis at an initial dose that is equivalent to the dose used in a patient with myositis as reported in the recent Lancet Rheumatology publication – — Second IND clearance for CABA-201, obtained within two months o

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 16, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 16, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation MAY 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Present

Regulation FD Disclosure, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 16, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Cabaletta Bio Reports First Quarter 2023 Financial Results and Provides Business Update – IND application cleared within 30 days for clinical trial of CABA-201 in patients with LN and SLE and Fast Track Designation granted by the FDA for CABA-201 to

EX-99.1 Exhibit 99.1 Cabaletta Bio Reports First Quarter 2023 Financial Results and Provides Business Update – IND application cleared within 30 days for clinical trial of CABA-201 in patients with LN and SLE and Fast Track Designation granted by the FDA for CABA-201 to deplete CD19-positive B cells and improve disease activity in patients with LN and SLE – – Phase 1/2 trial planned to evaluate CA

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 11, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 11, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Master Translational Research Services Agreement, dated as of February 9, 2023, between the Registrant and the Trustees of the University of Pennsylvania

Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. MASTER TRANSLATIONAL RESEARCH SERVICES AGREEMENT This Master Translational Research Services Agreement (“Agreemen

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Cabaletta Bio to Present at the American Society of Gene and Cell Therapy 26th Annual Meeting

EX-99.1 Exhibit 99.1 Cabaletta Bio to Present at the American Society of Gene and Cell Therapy 26th Annual Meeting PHILADELPHIA, May 2, 2023 — Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced that Samik Basu, M.D., Chief Scientific Officer

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 2, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 2, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Num

Cabaletta Bio Receives FDA Fast Track Designation for CABA-201

EX-99.2 Exhibit 99.2 Cabaletta Bio Receives FDA Fast Track Designation for CABA-201 PHILADELPHIA, May 1, 2023 — Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designa

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 1, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 1, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Num

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation MAY 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Present

Cabaletta Bio, Inc. 2929 Arch Street, Suite 600 Philadelphia, Pennsylvania 19104

Cabaletta Bio, Inc. 2929 Arch Street, Suite 600 Philadelphia, Pennsylvania 19104 April 24, 2023 Via EDGAR Transmission Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Attention: Alan R. Campbell Re: Cabaletta Bio, Inc.: Registration Statement on Form S-3 filed March 16, 2023 (File No. 333-270599) Ladies and Gentlemen: Pursuant to Rule 46

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

DEFA14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

DEF 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

- IND application cleared within 6 months of in-licensing CABA-201 binder - CABA-201 data package and experience from prior autoimmune cell therapy INDs informed Phase 1/2 clinical trial design, including the initial dose to be evaluated and the pati

EX-99.2 Exhibit 99.2 Cabaletta Bio Receives FDA Clearance of IND Application for CABA-201 for Treatment of Systemic Lupus Erythematosus - IND application cleared within 6 months of in-licensing CABA-201 binder - CABA-201 data package and experience from prior autoimmune cell therapy INDs informed Phase 1/2 clinical trial design, including the initial dose to be evaluated and the patient dosing int

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 31, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 31, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 2 d491365dex991.htm EX-99.1 Corporate Presentation March 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentati

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 16, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 16, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Power of Attorney (included on signature page).

S-8 As filed with the Securities and Exchange Commission on March 16, 2023 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Cabaletta Bio, Inc.

List of Subsidiaries of the Registrant

Exhibit 21.1 List of Subsidiaries None.

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.2 Corporate Presentation march 2023 Exhibit 99.2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Prese

Development, Manufacturing, and Testing Services Agreement, dated January 11, 2021, between the Registrant and WuXi Advanced Therapies Inc.

EX-10 4 caba-ex1034.htm EX-10.34 Exhibit 10.34 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. DEVELOPMENT, MANUFACTURING, AND TESTING SERVICES AGREEMENT This Development, Ma

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Cabaletta Bio, Inc.

Form of Subordinated Indenture between Registrant and one or more trustees to be named

Exhibit 4.4 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Subordinated Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1 Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4 Section 2.01 Designation and Terms of Securities 4 Section 2.02 Form of Securities and Trustee’s Certific

Cabaletta Bio Reports Fourth Quarter and Full Year 2022 Financial Results and Provides Business Update – Company expecting Investigational New Drug (IND) clearance in the first half of 2023 for CABA-201, a 4-1BB-containing fully human CD19-CAR T cell

Exhibit 99.1 Cabaletta Bio Reports Fourth Quarter and Full Year 2022 Financial Results and Provides Business Update – Company expecting Investigational New Drug (IND) clearance in the first half of 2023 for CABA-201, a 4-1BB-containing fully human CD19-CAR T cell therapy, with potential to generate initial clinical data by the first half of 2024 – PHILADELPHIA, March 16, 2023 – Cabaletta Bio, Inc.

Form of Senior Indenture between Registrant and one or more trustees to be named

EX-4.3 Exhibit 4.3 CABALETTA BIO, INC., Issuer AND [TRUSTEE], Trustee INDENTURE Dated as of [•], 202[•] Senior Debt Securities TABLE OF CONTENTS1 ARTICLE 1 DEFINITIONS 1 Section 1.01 Definitions of Terms 1 ARTICLE 2 ISSUE, DESCRIPTION, TERMS, EXECUTION, REGISTRATION AND EXCHANGE OF SECURITIES 4 Section 2.01 Designation and Terms of Securities 4 Section 2.02 Form of Securities and Trustee’s Certifi

Sales Agreement, dated as of March 16, 2023 between the Registrant and Cowen and Company, LLC

Exhibit 1.2 CABALETTA BIO, INC. $100,000,000 COMMON STOCK SALES AGREEMENT March 16, 2023 Cowen and Company, LLC 599 Lexington Avenue New York, NY 10022 Ladies and Gentlemen: Cabaletta Bio, Inc. (the “Company”), confirms its agreement (this “Agreement”) with Cowen and Company, LLC (“Cowen”), as follows: 1. Issuance and Sale of Shares. The Company agrees that, from time to time during the term of th

Form 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-39103 CABALETTA BIO,

Amendment No. 4, dated December 1, 2022, to the Sponsored Research Agreement, dated April 23, 2018, between the Registrant and the Trustees of the University of Pennsylvania

Exhibit 10.33 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH “[***]”. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. AMENDMENT NO. 4 TO SPONSORED RESEARCH AGREEMENT This Amendment No. 4 to the Sponsored Research Agreement (“Amend

Power of Attorney (included on signature pages hereto)

S-3 Table of Contents As filed with the Securities and Exchange Commission on March 16, 2023 Registration No.

Description of Securities

Exhibit 4.3 Description of the Registrant’s Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934, as amended The following summary of the general terms and provisions of the registered capital stock of Cabaletta Bio, Inc. (“Cabaletta”, “we”, “our”) does not purport to be complete and is subject to, and qualified in its entirety by, reference to our Third Amended and

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation march 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Prese

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 6, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 March 6, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File N

AGREEMENT

EX-99.1 2 tm234999d11ex99-1.htm EXHIBIT 99.1 EXHIBIT 99.1 AGREEMENT In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that this Statement on Schedule 13G relating to the Common Stock of Cabaletta Bio, Inc. is being filed with the Securities and Exchange Commission on behalf of each of them. February 14, 2023 BAKER BROS. ADVISORS

CABA / Cabaletta Bio Inc / Lynx1 Capital Management LP - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 p23-0352sc13ga.htm CABALETTA BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, $0.00001 par value per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing of this Statement) Check

CABA / Cabaletta Bio Inc / Eversept Partners, LP - SC 13G/A Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) Kamran Moghtaderi, Eversept Partners, L.P., 444 Madison Avenue, 22nd Floor, New York, NY 10022, 212-271-4211 (Name, Ad

CABA / Cabaletta Bio Inc / CITADEL ADVISORS LLC - SC 13G/A Passive Investment

SC 13G/A 1 tm233474-9sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G* (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2 (Amendment No. 2)* CABALETTA BIO, INC. (Name of Issuer) Common Stock, par value $0.00001 per share (the “Shares”) (Ti

CABA / Cabaletta Bio Inc / BAKER BROS. ADVISORS LP - SC 13G Passive Investment

SC 13G 1 tm234999d11sc13g.htm SC 13G SCHEDULE 13G SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 Under the Securities Exchange Act of 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2022 (Date of Event which Requires Filing of this Statement) Check the appropriate bo

CABA / Cabaletta Bio Inc / Nichtberger Steven - SC 13G/A Passive Investment

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to design

CABA / Cabaletta Bio Inc / Cormorant Asset Management, LP Passive Investment

SC 13G/A 1 sc13ga.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2022 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule purs

AGREEMENT REGARDING JOINT FILING OF STATEMENT ON SCHEDULE 13D OR 13G

EXHIBIT A AGREEMENT REGARDING JOINT FILING OF STATEMENT ON SCHEDULE 13D OR 13G The undersigned agree to file jointly with the Securities and Exchange Commission (the “SEC”) any and all statements on Schedule 13D or Schedule 13G (and any amendments or supplements thereto) required under section 13(d) of the Securities Exchange Act of 1934, as amended, in connection with purchases by the undersigned of the securities of any issuer.

CABA / Cabaletta Bio Inc / ALGER ASSOCIATES INC - CABALETTA BIO, INC. Passive Investment

SC 13G 1 d410308dsc13g.htm CABALETTA BIO, INC. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* CABALETTA BIO, INC. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) January 31, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to

CABA / Cabaletta Bio Inc / ADAGE CAPITAL PARTNERS GP, L.L.C. - CABALETTA BIO, INC. Passive Investment

SC 13G/A 1 p23-0746sc13ga.htm CABALETTA BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 3)* Cabaletta Bio, Inc. (Name of Issuer) Voting Common Stock, $0.00001 par value per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing of This Statement)

CABA / Cabaletta Bio Inc / COMMODORE CAPITAL LP Passive Investment

SC 13G 1 formsc13g.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) January 3, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box t

Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any docum

EX-99.1 Corporate Presentation JANUARY 2023 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Pre

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 January 9, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 January 9, 2023 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

CABA / Cabaletta Bio Inc / Venrock Healthcare Capital Partners III, L.P. - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, $0.00001 par value (Title of Class of Securities) 12674W109 (CUSIP Number) December 13, 2022 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuan

Form of Pre-Funded Warrant (incorporated by reference to Exhibit 4.1 to the Registrant’s Current Report on Form 8-K (File No. 001-39103) filed with the SEC on December 12, 2022)

EX-4.1 Exhibit 4.1 Form of Pre-Funded Warrant CABALETTA BIO, INC. WARRANT TO PURCHASE COMMON STOCK Number of Shares: [] (subject to adjustment) Warrant No. [] Original Issue Date: December [], 2022 Cabaletta Bio, Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [] or its registere

Underwriting Agreement, dated December 7, 2022, between Cabaletta Bio, Inc. and Cowen and Company, LLC, and Evercore Group L.L.C. as representatives of the several underwriters named therein.

EX-1.1 Exhibit 1.1 CABALETTA BIO, INC. 126,815 Shares of Common Stock Pre-Funded Warrants to purchase 6,213,776 Shares of Common Stock UNDERWRITING AGREEMENT December 7, 2022 COWEN AND COMPANY, LLC EVERCORE GROUP L.L.C. As Representatives of the several Underwriters c/o Cowen and Company, LLC 599 Lexington Avenue New York, New York 10022 c/o Evercore Group L.L.C. 55 East 52nd Street New York, New

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 December 7, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, IN

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 December 7, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

Cabaletta Bio Announces $35 Million Offering

EX-99.1 Exhibit 99.1 Cabaletta Bio Announces $35 Million Offering PHILADELPHIA, Dec. 8, 2022 — Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today announced that it has agreed to sell, by way of an underwritten public offe

Cabaletta Bio, Inc.

Filed Pursuant to Rule 433 under the Securities Act of 1933 Issuer Free Writing Prospectus dated December 7, 2022 Registration Statement No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 December 8, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, IN

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 December 8, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fil

126,815 Shares of Common Stock Pre-funded Warrants to Purchase 6,213,776 Shares of Common Stock

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-250006 PROSPECTUS SUPPLEMENT (To prospectus dated November 18, 2020) 126,815 Shares of Common Stock Pre-funded Warrants to Purchase 6,213,776 Shares of Common Stock We are selling 126,815 shares of our common stock, par value $0.00001 per share, or the common stock, in this offering and, in lieu of common stock to certai

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EX-99.1 Corporate Presentation DECEMBER 2022 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “Pr

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Exclusive License Agreement, dated October 7, 2022, by and between the Registrant and Nanjing IASO Biotherapeutics Co., LTD.(incorporated by reference to Exhibit 10.31 to the Registrant’s Quarterly Report on Form 10-Q (File No. 001-39103) filed on November 10, 2022

nvelope ID: 4CDBC5A9-258E-41FC-8002-AE5A57906617 Exhibit 10.1 CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT HAVE BEEN OMITTED AND REPLACED WITH ?[***]?. SUCH IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS (I) NOT MATERIAL AND (II) THE TYPE OF INFORMATION THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. EXCLUSIVE LICENSE AGREEMENT BY AND BETWEEN CABALETTA BIO, INC. A

Cabaletta Bio Reports Third Quarter 2022 Financial Results and Provides Business Update

EX-99.1 Exhibit 99.1 Cabaletta Bio Reports Third Quarter 2022 Financial Results and Provides Business Update PHILADELPHIA, Nov. 10, 2022 – Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on developing and launching the first curative targeted cell therapies for patients with autoimmune diseases, today reported financial results for the third quarter ended Septemb

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EX-99.2 Corporate Presentation november 2022 Exhibit 99.2 2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the “

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 10, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 November 10, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission Fi

CABA / Cabaletta Bio Inc / Nichtberger Steven - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the ru

CABA / Cabaletta Bio Inc / Cormorant Asset Management, LP Passive Investment

SC 13G 1 sc13g.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) October 20, 2022 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant

CABA / Cabaletta Bio Inc / Lynx1 Capital Management LP - CABALETTA BIO, INC Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, $0.00001 par value per share (Title of Class of Securities) 12674W109 (CUSIP Number) October 20, 2022 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 October 7, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 October 7, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

Cabaletta Bio and IASO Biotherapeutics Announce Exclusive Worldwide License Agreement for Clinically Validated CD19 Binder

Exhibit 99.2 Cabaletta Bio and IASO Biotherapeutics Announce Exclusive Worldwide License Agreement for Clinically Validated CD19 Binder PHILADELPHIA, Pennsylvania and SAN JOSE, California, NANJING and SHANGHAI, China ? October 11, 2022 ? IASO Biotherapeutics (?IASO Bio?), a clinical-stage biopharmaceutical company engaged in discovering, developing, and manufacturing innovative medicines and Cabal

Cabaletta Bio Announces CABA-201, a Newly Designed CD19-Targeting CAR T Cell Therapy Engineered to Address a Broad Range of Autoimmune Diseases

Exhibit 99.3 Cabaletta Bio Announces CABA-201, a Newly Designed CD19-Targeting CAR T Cell Therapy Engineered to Address a Broad Range of Autoimmune Diseases ? Company has obtained exclusive worldwide license for a fully human CD19 binder with clinical tolerability data that support potential clinical development in autoimmune diseases ? CABA-201 Investigational New Drug (IND) application planned f

2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any doc

Corporate Presentation OCTOBER 2022 Exhibit 99.1 2 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the ?Presentat

Regulation FD Disclosure, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 September 10, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission F

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Corporate Presentation SEPTEMBER 2022 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the ?Presentat

Cabaletta Bio Presents New Interim Data from the DesCAARTes™ Phase 1 Trial at the 31st EADV Congress

Exhibit 99.2 Cabaletta Bio Presents New Interim Data from the DesCAARTes? Phase 1 Trial at the 31st EADV Congress PHILADELPHIA, Sept. 10, 2022 ? Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on the discovery and development of targeted cell therapies for patients with autoimmune diseases, today presented updated clinical and translational data through 6 months

Cabaletta Bio to Present Data at the 31st EADV Congress and Provides Update on DesCAARTes™ Trial

Exhibit 99.1 Cabaletta Bio to Present Data at the 31st EADV Congress and Provides Update on DesCAARTes? Trial PHILADELPHIA, Aug. 29, 2022 ? Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on the discovery and development of targeted cell therapies for patients with autoimmune diseases, today announced that it will present new clinical and translational data from

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 29, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

AGREEMENT REGARDING JOINT FILING OF STATEMENT ON SCHEDULE 13D OR 13G

EXHIBIT A AGREEMENT REGARDING JOINT FILING OF STATEMENT ON SCHEDULE 13D OR 13G The undersigned agree to file jointly with the Securities and Exchange Commission (the ?SEC?) any and all statements on Schedule 13D or Schedule 13G (and any amendments or supplements thereto) required under section 13(d) of the Securities Exchange Act of 1934, as amended, in connection with purchases by the undersigned of the securities of any issuer.

CABA / Cabaletta Bio Inc / Eversept Partners, LP - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Cabaletta Bio, Inc. (Name of Issuer) Common Stock, par value $0.00001 per share (Title of Class of Securities) 12674W109 (CUSIP Number) Kamran Moghtaderi, Eversept Partners, L.P., 444 Madison Avenue, 22nd Floor, New York, NY 10022, 212-707-6113 (Name, Add

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Cabaletta Bio Reports Second Quarter 2022 Financial Results and Provides Business Update

Exhibit 99.1 Cabaletta Bio Reports Second Quarter 2022 Financial Results and Provides Business Update PHILADELPHIA, Aug. 11, 2022 ? Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on the discovery and development of targeted cell therapies for patients with autoimmune diseases, today reported financial results for the second quarter ended June 30, 2022, and provi

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Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 August 11, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File

CABA / Cabaletta Bio Inc / 5AM Ventures V, L.P. - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-l(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a) (Amendment No. 5)* Cabaletta Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 12674W109 (CUSIP Number) Rebecca Lucia 5AM Venture Management, LLC 501 2

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 June 1, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

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Corporate Presentation MAY 2022 Exhibit 99.1 Disclaimer The following presentation, including any printed or electronic copy of these slides, the talks given by the presenters, the information communicated during any delivery of the presentation and any question and answer session and any document or material distributed at or in connection with the presentation (collectively, the ?Presentation?)

Cabaletta Bio Presents Updated Interim DesCAARTes™ Trial Phase 1 Data at the ASGCT 25th Annual Meeting

Exhibit 99.2 Cabaletta Bio Presents Updated Interim DesCAARTes? Trial Phase 1 Data at the ASGCT 25th Annual Meeting PHILADELPHIA, May 18, 2022 ? Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on the discovery and development of targeted cell therapies for patients with autoimmune diseases, today presented updated clinical and translational data through 6 months

Regulation FD Disclosure, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 18, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39103 CABALETTA BIO, INC.

Cabaletta Bio Reports First Quarter 2022 Financial Results and Provides Business Update – DesCAARTes™ trial clinical and translational data from cohorts A3 and A4 and 28-day safety data from cohort A5 expected to be presented at upcoming scientific m

Exhibit 99.1 Cabaletta Bio Reports First Quarter 2022 Financial Results and Provides Business Update ? DesCAARTes? trial clinical and translational data from cohorts A3 and A4 and 28-day safety data from cohort A5 expected to be presented at upcoming scientific meetings in mid-2022 ? Multiple abstracts accepted for presentation at upcoming ASGCT and SID Annual Meetings ? MuSK-CAART first-in-human

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)

Exhibit 3.3 AMENDMENT TO THE AMENDED AND RESTATED BY-LAWS OF CABALETTA BIO, INC. (the ?Corporation?) Section 8 of Article VI of the Amended and Restated By-laws of the Corporation (the ?Bylaws?), is hereby amended and restated in its entirety to read as follows: ?SECTION 8. Exclusive Jurisdiction of Delaware Courts or the United States Federal District Courts. Unless the Corporation consents in wr

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 12, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Nu

Cabaletta Bio to Present DSG3-CAART Clinical Data and MuSK-CAART Preclinical Data at Upcoming Scientific Meetings in May

Exhibit 99.1 Cabaletta Bio to Present DSG3-CAART Clinical Data and MuSK-CAART Preclinical Data at Upcoming Scientific Meetings in May PHILADELPHIA, May 2, 2022 ? Cabaletta Bio, Inc. (Nasdaq: CABA), a clinical-stage biotechnology company focused on the discovery and development of targeted cell therapies for patients with autoimmune diseases, today announced that data from its two lead programs, DS

Regulation FD Disclosure, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 May 2, 2022 Date of Report (Date of earliest event reported) CABALETTA BIO, INC. (Exact name of Registrant as Specified in its Charter) Delaware 001-39103 82-1685768 (State or other jurisdiction of incorporation) (Commission File Num

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.) Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

DEF 14A 1 d292029ddef14a.htm DEF 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Us

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Cabaletta Bio, Inc.

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)

Exhibit 10.26 FIRST AMENDMENT TO LEASE THIS FIRST AMENDMENT TO LEASE (?Amendment?) is made and entered into as of February 15, 2022, by and between BRANDYWINE CIRA, L.P., a Pennsylvania limited partnership (?Landlord?), and CABALETTA BIO, INC., a Delaware corporation (?Tenant?). A.Landlord and Tenant are parties to a Lease (?Current Lease?) dated as of February 11, 2019, for the Premises deemed to