8-K

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 12, 2026

    

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 Number)	(IRS Employer Identification No.)

2929 Arch Street Suite 600
Philadelphia, Pennsylvania		19104
(Address of Principal Executive Offices)		(Zip Code)

     Registrant’s Telephone Number, Including Area Code: (267) 759-3100

    

     Not Applicable

    

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.00001 per share	CABA	The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 7.01 Regulation FD Disclosure.

On January 12, 2026, Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) issued a press release announcing its 2026 strategic priorities (the “Press Release”). A copy of the Press Release is furnished herewith as Exhibit 99.1 to this Current Report on Form 8-K.

The information contained in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1 and 99.2 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of 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 or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Item 8.01 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 into a pipeline in a product across autoimmune diseases

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Initiation of myositis registrational cohort: Cabaletta initiated the U.S. Food and Drug Administration (FDA)-aligned dermatomyositis (DM) and antisynthetase syndrome (ASyS) registrational cohort in December 2025. These subtypes affect approximately 70,000 patients in the U.S., with DM comprising approximately 60,000 patients. The registrational cohort is expected to evaluate 17 patients with a 16-week primary endpoint of moderate or major total improvement score response while off immunomodulators and on no or low-dose steroids. Data from the Phase 1/2 RESET-Myositis® trial presented at ACR Convergence 2025 demonstrated that all DM patients with sufficient follow-up who would have met key inclusion criteria in the registrational cohort achieved the registrational primary endpoint with durability throughout the follow-up period as long as one year. Based on that data, Cabaletta elected to expand the registrational trial by 3 patients to permit enrollment of approximately 14 DM patients aligned with natural U.S. prevalence estimates. If successful, data from this cohort will support Cabaletta’s first projected Biologics License Application (BLA) submission for rese-cel in myositis next year.

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FDA alignment on new registrational cohort designs in SLE and LN: Cabaletta has aligned with the FDA on registrational cohort designs in RESET-SLE to evaluate the current rese-cel weight-based dose of 1 million cells/kg in a single infusion with preconditioning, including two independent, single-arm cohorts, one consisting of patients with non-renal systemic lupus erythematosus (SLE) and one consisting of patients with lupus nephritis (LN), each evaluating approximately 25 patients with unique endpoints in each cohort. Cabaletta will provide an update on next steps for these cohorts later this year subject to dose-ranging data evaluating rese-cel without preconditioning in lupus patients.

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Additional RMAT designation granted and registrational cohort alignments and initiations anticipated in 2026: The FDA has recently granted a Regenerative Medicine Advanced Therapy (RMAT) designation to rese-cel for the treatment of systemic sclerosis. Cabaletta is continuing to engage with the FDA to align on registrational cohort designs for RESET-SSc™ and anticipates providing an update regarding registrational alignment for RESET-SSc in 1H26 and RESET-MG™ in mid-2026.

Advance fully automated, scalable manufacturing with Cellares to support the anticipated post-approval market expansion of rese-cel

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Automated manufacturing of rese-cel using the Cellares Cell Shuttle™ and Cellares Cell Q™ to initiate imminently: Investigational New Drug (IND) amendment clearance has been obtained to use the Cellares Cell Shuttle to manufacture rese-cel. This is a first for any autologous CAR T program. The IND submission included three engineering runs that demonstrated product consistency compared to existing rese-cel manufacturing runs at current contract development and manufacturing organizations (CDMOs) and is the result of the collaboration between Cabaletta and Cellares since 2023. This follows the previously announced completion of the Technology Adoption Program which successfully demonstrated the ability of Cellares’ Cell Shuttle to automate the rese-cel manufacturing process. Cabaletta anticipates clinical manufacturing data in the first half of 2026, which is intended to confirm overall supply chain GMP readiness, including supply chain logistics, for Cellares-produced rese-cel implementation across the rese-cel portfolio. The Company continues to work with its existing manufacturing partners to support the myositis registrational trial and launch-readiness efforts for rese-cel. The Cellares Integrated Development and Manufacturing Organization (IDMO) Smart Factory can enable unprecedented scale with minimal capital investment, rapid expansion to global capacity, lower manufacturing cost and improve scheduling flexibility for rese-cel after commercialization.

Expand the clinical experience of rese-cel and in combination with process innovations to deliver an industry-leading therapy for patients and physicians

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No preconditioning dose-escalation ongoing in RESET-PV: Following the presentation of the first rese-cel data demonstrating biologic activity and early clinical responses without preconditioning at the 2025 European Society of

Gene & Cell Therapy Annual Congress, Cabaletta is now evaluating rese-cel at a higher dose without preconditioning in patients with pemphigus vulgaris with additional patients currently enrolled. Additional durability data from patients dosed at the initial dose and initial clinical data from patients dosed at the higher dose are expected in 1H26.

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No preconditioning cohort added in RESET-SLE: Cabaletta has incorporated a dose-escalation cohort without preconditioning in RESET-SLE, which is the current focus for the trial. This decision was based on the safety and activity data at the initial dose evaluating rese-cel without preconditioning in the RESET-PV study and the clinical responses observed in lupus following complete B cell depletion after administration of rese-cel with preconditioning. Pending dose-ranging clinical data anticipated in 2026, Cabaletta will evaluate pursuing alignment with the FDA on a registrational pathway for the no preconditioning cohort.

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Complete Phase 1/2 data readouts across three RESET™ trials expected in 1H26: Following the presentation of complete Phase 1/2 clinical data from RESET-Myositis cohorts in 2025, Cabaletta anticipates complete Phase 1/2 clinical data from cohorts in RESET-SLE, RESET-SSc and RESET-MG in 1H26.

About rese-cel (resecabtagene autoleucel)

Rese-cel (formerly referred to as CABA-201) is an investigational, autologous CAR T cell therapy engineered with a fully human CD19 binder and a 4-1BB co-stimulatory domain, designed specifically for the treatment of autoimmune diseases. Administered as a single, weight-based infusion, rese-cel is intended to transiently and deeply deplete CD19-positive cells, with the goal of resetting the immune system and achieving durable clinical responses without the need for chronic therapy. Cabaletta is evaluating rese-cel in the RESET™ (REstoring SElf-Tolerance) clinical development program, which includes multiple ongoing company-sponsored trials across a diverse and growing range of autoimmune diseases in rheumatology, neurology and dermatology.

About Cabaletta Bio
Cabaletta Bio (Nasdaq: CABA) is a late-stage clinical biotechnology company focused on developing and launching the first curative targeted cell therapies designed specifically for patients with autoimmune diseases. The CABA™ platform encompasses two complementary strategies which aim to advance the discovery and development of engineered T cell therapies with the potential to become deep and durable, perhaps curative, treatments for a broad range of autoimmune diseases. The lead CARTA (Chimeric Antigen Receptor T cells for Autoimmunity) strategy is prioritizing the development of rese-cel, a 4-1BB-containing fully human CD19-CAR T cell investigational therapy. Rese-cel is currently being evaluated in the RESET™ (REstoring SElf-Tolerance) clinical development program spanning multiple therapeutic areas, including rheumatology, neurology and dermatology. Cabaletta Bio’s headquarters and labs are located in Philadelphia, PA. For more information, please visit www.cabalettabio.com and connect with us on LinkedIn.

Forward-Looking Statements

This press release contains “forward-looking statements” of Cabaletta Bio within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including without limitation, express or implied statements regarding: Cabaletta’s business plans and objectives as a whole; Cabaletta’s ability to realize its vision of launching the first curative targeted cell therapy designed specifically for patients with autoimmune diseases; Cabaletta’s ability to successfully complete research and further development and commercialization of its drug candidates in current or future indications, including the timing and results of Cabaletta’s clinical trials and its ability to conduct and complete clinical trials; expectation that clinical results will support rese-cel’s safety and activity profile; statements regarding the timing of interactions with regulatory authorities, including such authorities’ review of safety information from Cabaletta’s ongoing clinical trials and alignment with regulatory authorities on potential registrational pathway for rese-cel; Cabaletta’s ability to leverage its emerging clinical data and its efficient development strategy; Cabaletta’s plans to advance a new generation of autologous innovations that can support scalable outpatient use with attractive margins and minimal capital investment; Cabaletta’s belief that clinical data without preconditioning, if durable, may further increase access for patients; Cabaletta’s ability to capitalize on and potential benefits resulting from its research and translational insights; the clinical significance of the clinical data read-out at upcoming scientific meetings and timing thereof; Cabaletta’s expectations around the potential success and therapeutic benefits of rese-cel, including its belief that rese-cel has the potential to reset the immune system and achieve durable clinical responses without the need for chronic therapy; the Company’s advancement of separate Phase 1/2 clinical trials of rese-cel in patients with SLE, myositis, SSc, gMG and PV and advancement RESET-MS trial, including updates related to status, enrollment, safety data, efficiency of clinical trial design and timing of data read-outs or otherwise; Cabaletta’s plans to submit a BLA for rese-cel in myositis in 2027 and obtain regulatory approval from the FDA and other regulatory authorities, among others.

Any forward-looking statements in this press release 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 ability to demonstrate sufficient evidence of safety, efficacy and tolerability in its preclinical studies and clinical trials of rese-cel; the risk that the results observed with the similarly-designed construct employed in academic publications, including due to the dosing regimen, are not indicative of the results we seek to achieve with rese-cel; risks that results from one program may not translate to results for another program; risks that modifications to trial design or approach may not have the intended benefits and that the trial design may need to be further modified; risks related to clinical trial site activation, delays in enrollment generally or enrollment rates that are lower than expected; delays related to assessment of clinical trial results; risks related to unexpected safety or


	CABALETTA BIO, INC.

Date: January 12, 2026	By:	/s/ Steven Nichtberger
		Steven Nichtberger
		Chief Executive Officer and President (Principal Executive Officer)



99.1		Press Release issued by the registrant on January 12, 2026, furnished herewith.

99.2		Cabaletta Bio, Inc. Corporate Presentation, dated January 2026, filed herewith.

104		Cover Page Interactive Data File (embedded within the Inline XBRL Document).