of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Other Events. On June 3, 2026, the Company posted to the “Investors & Media” section of the Company’s website at www.cabalettabio.com an updated corporate presentation (the “Corporate Presentation”). A copy of the Corporate Presentation is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference. On June 3, 2026, the Company issued the Press Release announcing new rese-cel data and development updates across the Company's autoimmune portfolio, in…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Other Events. On May 14, 2026, the Company posted to the “Investors & Media” section of the Company’s website at www.cabalettabio.com an updated corporate presentation (the “Corporate Presentation”). A copy of the Corporate Presentation is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference. On May 14, 2026, the Company issued the Press Release presenting its preconditioning-free clinical data and automated manufacturing translational data f…

Other Events. The full text of the press release announcing the pricing of the underwritten offering on May 4, 2026 is attached as Exhibit 99.1 hereto and is incorporated herein by reference. The Company currently intends to use the net proceeds from this offering together with its existing cash and cash equivalents, primarily to fund the expanded clinical development of rese-cel in multiple indications with and/or without preconditioning, including the ongoing myositis registrational study a…

Results of Operations and Financial Condition. As of March 31, 2026, the Company had approximately $117 million in cash and cash equivalents. This preliminary financial information is subject to completion, and is the responsibility of management and has been prepared in good faith on a consistent basis with prior periods. However, the Company has not reported its financial results for the three months ended March 31, 2026, and its actual results could be materially different from this prelim…

Entry into a Material Definitive Agreement. On May 4, 2026, Cabaletta Bio, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with TD Securities (USA) LLC, Guggenheim Securities, LLC and Cantor Fitzgerald & Co. (collectively, the “Underwriters”), relating to an underwritten registered direct offering (the “Offering”) of 51,725,000 shares (the “Shares”) of the Company’s common stock, $0.00001 par value per share (the “Common Stock”). The Shares are being…

are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: risks related to regulatory filings and potential clearance; the risk that signs of biologic activity or persistence may not inform long-term results; Cabaletta’s ab…

Results of Operations and Financial Condition. On March 23, 2026, Cabaletta Bio, Inc. (the "Company") announced its financial results for the fourth quarter and fiscal year ended December 31, 2025. A copy of the press release is being furnished as Exhibit 99.1 to this Report on Form 8-K.

Other Events. On January 12, 2026, the Company posted to the “Investors & Media” section of the Company’s website at www.cabalettabio.com an updated corporate presentation (the “Corporate Presentation”). A copy of the Corporate Presentation is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference. On January 12, 2026, the Company issued the Press Release announcing its 2026 strategic priorities. Translate registrational pathways with rese-cel…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Entry into a Material Definitive Agreement. On June 11, 2025, Cabaletta Bio, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, TD Securities (USA) LLC and Cantor Fitzgerald & Co. (collectively, the “Underwriters”), relating to an underwritten offering (the “Offering”) of (i) 39,200,000 shares (the “Shares”) of the Company’s common stock, $0.00001 par value per share (the “Common Stock”), (ii) in lieu of Common Stock to certain inves…

Termination of a Material Definitive Agreement. As previously disclosed, on March 21, 2024, Cabaletta Bio, Inc. (the “Company”) entered into a Sales Agreement (the “Sales Agreement”) with TD Securities (USA) LLC (“TD Cowen”), pursuant to which the Company may sell from time to time, at its option, up to an aggregate of $200,000,000 of shares of the its Common Stock (the “ATM Shares”), through TD Cowen as the Company’s sales agent (the “ATM Program”). On June 11, 2025, the Company and TD Cowen…

The company repriced underwater stock options for current employees and certain directors to retain and motivate them.

of this Form 8-K does not present all information necessary for an understanding of the Company’s financial condition as of March 31, 2025 and is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exch…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

of this Current Report on Form 8-K is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific refere…

Entry Into a Material Definitive Agreement. On September 30, 2024, Cabaletta Bio, Inc. (the “ Company ”) entered into an Amendment to Service Agreement (the “ Lease Amendment ”) with CIC Innovation Communities, LLC (“ CIC ”), to be effective as of October 1, 2024, which amends the Company’s existing Service Agreement with CIC, dated as of February 1, 2019, as amended December 1, 2021 (the “ Existing Lease ” and, together with the Lease Amendment, the “ Lease ”), to revise the Company’s paymen…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific refere…

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific refere…

Results of Operations and Financial Condition. On May 15, 2024, Cabaletta Bio, Inc. (the “Company”) announced its financial results for the first quarter ended March 31, 2024. A copy of the press release is being furnished as Exhibit 99.1 to this Report on Form 8-K. The information contained in

of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing

Results of Operations and Financial Condition. On January 8, 2024, Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) disclosed that its unaudited cash, cash equivalents and short-term investments as of December 31, 2023 was $241 million. This cash balance is inclusive of the sale of 4,760,899 shares of common stock in the fourth quarter of 2023 under the Company’s “at-the-market” sales program (“ATM Program”) pursuant to the Sales Agreement, dated March 16, 2023 with Cowen and Company, LLC (…