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

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 Number)	(I.R.S. Employer Identification No.)

2929 Arch Street, Suite 600, Philadelphia, PA	19104
(Address of principal executive offices)	(Zip Code)

(267) 759-3100

(Registrant’s telephone number, including area code)

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 2.02 Results of Operations and Financial Condition.

On August 8, 2024, Cabaletta Bio, Inc. (the “Company”) announced its financial results for the second quarter ended June 30, 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 Item 2.02 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 reference in such filing.

Item 7.01 Regulation FD Disclosure

On August 8, 2024, 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 and is incorporated by reference into this Item 7.01 of this Current Report on Form 8-K.

The information contained in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.2 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 9.01 Financial Statements and Exhibits.

(d) Exhibits

99.1	Press Release issued by the registrant on August 8, 2024, furnished herewith.
99.2	Cabaletta Bio, Inc. Corporate Presentation, dated August 8, 2024, furnished herewith.
104	Cover Page Interactive Data File (embedded within the Inline XBRL Document).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.

	CABALETTA BIO, INC.
Date: August 8, 2024	By:	/s/ Steven Nichtberger
		Steven Nichtberger, M.D.
		President and Chief Executive Officer

EX-99.1

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-SSc^™ and RESET-MG^™ trials anticipated in 2H24 –

– Initial clinical and translational data from each of the first patients in the RESET-Myositis and RESET-SLE trials presented at EULAR in June 2024 –

– An LN patient with very active, refractory disease dosed with CABA-201 in late June experienced a protocol-defined dose-limiting toxicity of Grade 4 ICANS, which resolved rapidly following standard management; the independent data monitoring committee recommended the study to proceed as designed, without delay, at the current dose –

– Recently signed Lonza and Cellares agreements support progression into next stage of manufacturing strategy to support expansion of clinical supply while preparing to efficiently scale commercial supply for CABA-201 –

– Cash, cash equivalents and short-term investments total $203.2 million as of June 30, 2024, expected to support operations into the first half of 2026 –

PHILADELPHIA, Aug. 8, 2024 – Cabaletta Bio, Inc. (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, today reported financial results for the second quarter ended June 30, 2024, and provided a business update.

“We have seen increased enrollment and additional clinical sites open since presenting positive initial clinical and translational data for the first two patients dosed with CABA-201 at the EULAR 2024 Congress in June. We look forward to sharing additional clinical data on CABA-201 in the second half of this year,” said Steven Nichtberger, M.D., Chief Executive Officer of Cabaletta. “In addition, we have recently advanced our manufacturing strategy for CABA-201 through a new CDMO agreement with Lonza and by expanding our existing fully automated manufacturing collaboration with Cellares. We have also added Sarah Yuan, Ph.D., as our Chief Technology Officer. Sarah brings substantial cell therapy development and commercial launch experience, including at bluebird bio and 2seventy bio, where she was instrumental in the regulatory approval process for Abecma^™ and two other cell therapy medicines. With the momentum and milestones achieved in the second quarter and recent period, we believe we are well positioned to realize our vision of developing and launching the first curative targeted cell therapy for patients with autoimmune diseases.”

Recent Operational Highlights and Upcoming Anticipated Milestones

Chimeric Antigen Receptor T cells for Autoimmunity (CARTA) Strategy

CABA-201: Autologous, engineered T cells designed with a chimeric antigen receptor containing a fully human CD19 binder and a 4-1BB co-stimulatory domain as a potential treatment for a broad range of autoimmune diseases where B cells contribute to the initiation and/or maintenance of disease.

Rheumatology Portfolio

• Myositis (idiopathic inflammatory myopathies, IIM)

• In June 2024, Cabaletta reported positive initial clinical data on the first patient in the immune-mediated necrotizing myopathy (IMNM) cohort of the Phase 1/2 RESET-Myositis trial with three months of follow-up. The data were presented at a satellite symposium at the EULAR 2024 Congress.

• Patient enrollment in the RESET-Myositis trial is ongoing and additional clinical data from the trial are expected in the second half of 2024.

• Systemic lupus erythematosus (SLE)

• In June 2024, Cabaletta reported positive initial clinical data on the first patient in the SLE non-renal cohort of the Phase 1/2 RESET-SLE trial with one month of follow-up. The data were presented at a satellite symposium at the EULAR 2024 Congress.

• In late June 2024, a lupus nephritis (LN) patient with very active, refractory disease was dosed with CABA-201 and subsequently experienced a protocol-defined dose-limiting toxicity of grade 4 immune effector cell-associated neurotoxicity syndrome (ICANS). The ICANS resolved rapidly following standard management. After data review, the Independent Data Monitoring Committee recommended that the study proceed at the current dose without delay. The Company has proposed and is implementing protocol modifications designed to improve patient safety, including enhanced monitoring for fever and neurologic symptoms along with seizure prophylaxis for all patients, in line with the practice at many academic sites including at Erlangen University, the site of the CD19-CAR T studies led by Dr. Georg Schett. Last month, the Company communicated details of the event and proposed protocol changes to all active clinical sites within the RESET clinical trial program.

• Patient enrollment in both cohorts of the RESET-SLE trial is ongoing and additional clinical data from the trial are expected in the second half of 2024.

• Systemic sclerosis (SSc)

• Patient enrollment in the Phase 1/2 RESET-SSc^™ trial is ongoing and initial clinical data from the trial are expected in the second half of 2024.

Neurology Portfolio

• Generalized myasthenia gravis (gMG)

• Patient enrollment in the Phase 1/2 RESET-MG^™ trial is ongoing and initial clinical data from the trial are expected in the second half of 2024.

Dermatology Portfolio

• Pemphigus vulgaris (PV)

• Cabaletta is working with active clinical sites to incorporate the RESET-PV^™ sub-study within the Phase 1 DesCAARTes^™ trial following the submission of a protocol amendment. The RESET-PV sub-study will evaluate CABA-201 as a monotherapy without preconditioning in patients with mucosal PV (mPV) and mucocutaneous PV (mcPV).

External Scientific Presentations and Publications

• In May 2024, Cabaletta’s manuscript on the preclinical characterization of CABA-201 titled “Preclinical specificity and activity of a fully human 4-1BB expressing anti-CD19 CART therapy for treatment-resistant autoimmune disease” was published in Molecular Therapy Methods & Clinical Development. The preclinical data support the evaluation of CABA-201 for clinical development in patients with autoimmune diseases and were included within the Investigational New Drug submissions for CABA-201.

• In June 2024, Cabaletta presented positive initial clinical data from each of the first two patients dosed with CABA-201 in the RESET-Myositis and RESET-SLE trials at a EULAR European Congress of Rheumatology 2024 Industry Symposia session titled “Immune Reset: The Potential of CAR T Cell Therapy to Transform the Treatment of Patients with Autoimmune Disease” in Vienna, Austria. The initial clinical data demonstrated:

• CABA-201 was generally well-tolerated with no serious adverse events reported for either patient through the follow-up period.

• CABA-201 exhibited its anticipated profile of CAR T cell expansion and contraction with complete B cell depletion observed in both patients by day 15 post-infusion.

• Improvements in both patients’ specific disease measures, consistent with the academic experience of a similar 4-1BB CD19-CAR T, suggest a potential emerging clinical benefit with CABA-201.

• Immature, naïve B cell repopulation in first IMNM patient observed at week 8 is consistent with a potential immune system reset.

Chimeric AutoAntibody Receptor T (CAART) cells Strategy

• DSG3-CAART: Cabaletta is evaluating desmoglein 3 chimeric autoantibody receptor T (DSG3-CAART) cells as a potential treatment for patients with mPV. The DesCAARTes trial is no longer dosing patients with DSG3-CAART after evaluation of clinical and translational data from the combination cohort, where patients were pre-treated with IVIg, cyclophosphamide and fludarabine prior to DSG3-CAART infusion.

• MuSK-CAART: Cabaletta is evaluating muscle-specific kinase (MuSK) chimeric autoantibody receptor T (MuSK-CAART) cells as a potential treatment for patients with MuSK-associated myasthenia gravis (MuSK MG). Based on review of the initial clinical data and the data from the DSG3-CAART trial, the MusCAARTes^™ trial is currently dosing patients in the A2 cohort, where patients are treated with MuSK-CAART without preconditioning.

Manufacturing Leadership and Strategy Updates

• In June 2024, Sarah Yuan, Ph.D., joined the Company as Chief Technology Officer. Dr. Yuan possesses over 20 years of experience in process development and manufacturing strategy leadership in the life sciences industry and most recently served as Chief Technical Operations Officer at Sigilon Therapeutics, Inc., a wholly owned subsidiary of Eli Lilly & Co. Prior to that, Dr. Yuan was Vice President of Process and Analytical Development at bluebird bio and 2seventy bio, where she was instrumental in the regulatory approval process for Abecma^™ and two additional cell therapy medicines. Dr. Yuan reports to Gwendolyn Binder, Ph.D., President of Science and Technology of Cabaletta, and is responsible for the process and analytical development, manufacturing strategy, and supply chain operations, in addition to supporting CMC quality control.

• In July 2024, Cabaletta entered into a new manufacturing agreement with Lonza, a leading Contract Development and Manufacturing Organization (CDMO). Under the terms of the agreement, a technology transfer of the manufacturing process for CABA-201 will be performed from Cabaletta to Lonza in anticipation of being able to supply Good Manufacturing Practices (GMP) products to support any of Cabaletta’s current and planned clinical trials that evaluate CABA-201, including potential late-stage clinical trials and commercial readiness activities for CABA-201.

• In August 2024, Cabaletta expanded its original November 2023 partnership with Cellares, the first Integrated Development and Manufacturing Organization (IDMO) dedicated to clinical and industrial-scale cell therapy manufacturing, following a successful initial proof-of-concept technology transfer process for the manufacture of CABA-201 using the Cell Shuttle^™. The expanded partnership facilitates the potential to incorporate Cellares’ manufacturing platform in the CABA-201 clinical program.

Second Quarter 2024 Financial Results

• Research and development expenses were $23.4 million for the three months ended June 30, 2024, compared to $11.8 million for the same period in 2023.

• General and administrative expenses were $6.9 million for the three months ended June 30, 2024, compared to $4.1 million for same period in 2023.

• As of June 30, 2024, Cabaletta had cash, cash equivalents and short-term investments of $203.2 million, compared to $241.2 million as of December 31, 2023.

The Company expects that its cash, cash equivalents and short-term investments as of June 30, 2024, will enable it to fund its operating plan into the first half of 2026.

About CABA-201

CABA-201 is designed to deeply and transiently deplete CD19-positive cells following a one-time infusion, which may enable an “immune system reset” with the potential for durable remission without chronic therapy in patients with autoimmune diseases. Cabaletta is evaluating CABA-201 in multiple autoimmune conditions within five disease-specific company sponsored INDs including myositis (idiopathic inflammatory myopathy, or IIM), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), generalized myasthenia gravis (gMG), and pemphigus vulgaris (PV; a sub-study to evaluate CABA-201 without preconditioning).

About Cabaletta Bio

Cabaletta Bio (Nasdaq: CABA) is a clinical-stage biotechnology company focused on the discovery and development of engineered T cell therapies that have the potential to provide a deep and durable, perhaps curative, treatment for patients with autoimmune diseases. The CABA^™ platform encompasses two strategies: the CARTA (chimeric antigen receptor T cells for autoimmunity) strategy, with CABA-201, a 4-1BB-containing fully human CD19-CAR T, as the lead product candidate being evaluated in the RESET^™ (REstoring SElf-Tolerance) clinical trials in myositis, systemic lupus erythematosus, systemic sclerosis, generalized myasthenia gravis and in the RESET-PV^™ sub-study within the DesCAARTes^™ clinical trial in pemphigus vulgaris, along with the CAART (chimeric autoantibody receptor T cells) strategy, with multiple clinical-stage candidates, including DSG3-CAART for mucosal pemphigus vulgaris and MuSK-CAART for MuSK-associated myasthenia gravis. The expanding CABA^™ platform is designed to develop potentially curative therapies that offer deep and durable responses for patients with a broad range of autoimmune diseases. Cabaletta Bio’s headquarters and labs are located in Philadelphia, PA.

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 ability to grow its autoimmune pipeline; Cabaletta’s business plans and objectives as a whole; Cabaletta’s ability to realize its vision of launching the first curative targeted cell therapy 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; the uncertainties inherent in clinical testing and accruing patients for clinical trials; the timing and results of Cabaletta’s clinical trials, as well as its ability to conduct and complete clinical trials; expectation that clinical results will support CABA-201’s safety and activity profile; statements regarding the expectations of trial modifications and prophylactic measures, continued trial operations; statements regarding the timing of regulatory filings and interactions with regulatory authorities, including such authorities’ review of safety information from Cabaletta’s ongoing clinical trials; Cabaletta’s ability to retain and recognize and its expectations around the intended incentives conferred by Fast Track Designation for CABA-201 for the treatment of multiple autoimmune diseases; Cabaletta’s expectations around the potential success and therapeutic benefits of CABA-201, including its belief that CABA-201 may enable an “immune system reset” with the potential for durable remission without chronic therapy in patients with autoimmune diseases; the Company’s advancement of separate Phase 1/2 clinical trials of CABA-201 in patients with SLE, myositis, SSc and gMG and advancement of a RESET-PV sub-study within the ongoing DesCAARTes trial in PV, including updates related to status, safety data, or otherwise and the expected timing of the related data read-outs; Cabaletta’s ability to accelerate its pipeline, develop meaningful therapies for patients and leverage its research and translational insights and its expanding manufacturing partnerships; Cabaletta’s ability to execute its manufacturing strategy to enable expansion of clinical supply and efficiently scale commercial supply for CABA-201; Cabaletta’s planned additional clinical data read-out for patients with myositis and SLE treated with CABA-201; Cabaletta’s planned initial clinical data read-outs for patients with SSc and gMG treated with CABA-201 or otherwise; Cabaletta’s ability to increase enrollment from its rapidly expanding clinical network in the RESET clinical program; Cabaletta’s planned assessment of its DesCAARTes^™ and MusCAARTes^™ trials; use of capital, expense and other financial results in the future; ability to fund operations into the first half of 2026 and the anticipated contribution of the members of Cabaletta’s executives to the company’s operations and progress.

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 CABA-201; 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 CABA-201; 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 efficacy data observed during clinical studies; risks related to volatile market and economic conditions and public health crises; Cabaletta’s ability to retain and recognize the intended incentives conferred by Orphan Drug Designation and Fast Track Designation or other designations for its product candidates, as applicable; risks related to Cabaletta’s ability to protect and maintain its intellectual property position; risks related to fostering and maintaining successful relationships with Cabaletta’s collaboration and manufacturing partners, including in light of recent legislation; uncertainties related to the initiation and conduct of studies and other development requirements for its product candidates; the risk that any one or more of Cabaletta’s product candidates will not be successfully developed and/or commercialized; and the risk that the initial or interim results of preclinical studies or clinical studies will not be predictive of future results in connection with future studies. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause Cabaletta’s actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in Cabaletta’s most recent annual report on Form 10-K as well as discussions of potential risks, uncertainties, and other important factors in Cabaletta’s other filings with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and Cabaletta undertakes no duty to update this information unless required by law.

CABALETTA BIO, INC.

SELECTED FINANCIAL DATA

(unaudited; in thousands, except share and per share data)

Statements of Operations

	Three Months Ended June 30,						Six Months Ended June 30,
	2024			2023			2024			2023
	unaudited						unaudited
Operating expenses:
Research and development	$	23,427		$	11,797		$	45,381		$	24,232
General and administrative		6,852			4,093			12,929			8,614
Total operating expenses		30,279			15,890			58,310			32,846
Loss from operations		(30,279	)		(15,890	)		(58,310	)		(32,846	)
Other income:
Interest income		2,677			1,403			5,661			2,505
Net loss		(27,602	)		(14,487	)		(52,649	)		(30,341	)
Net loss per share of voting and non-voting common stock, basic and diluted	$	(0.56	)	$	(0.37	)	$	(1.07	)	$	(0.81	)

Selected Balance Sheet Data

	June 30, 2024		December 31, 2023
	(unaudited)
Cash, cash equivalents and investments	$	203,225	$	241,249
Total assets		217,418		253,650
Total liabilities		17,899		17,452
Total stockholders’ equity		199,519		236,198

Contacts:

Anup Marda

Chief Financial Officer

investors@cabalettabio.com

William Gramig

Precision AQ

william.gramig@precisionaq.com

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 “Presentation”) has been prepared by Cabaletta Bio, Inc. (“we,” “us,” “our,” “Cabaletta” or the “Company”) and is made for informational purposes only. This Presentation does not purport to be a prospectus, to be complete or to contain all of the information you may desire. Statements contained herein are made as of the date of this Presentation unless stated otherwise, and this Presentation shall not under any circumstances create an implication that the information contained herein is correct as of any time after such date or that information will be updated or revised to reflect information that subsequently becomes available or changes occurring after the date hereof. This Presentation may contain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 relating to our business, operations, and financial conditions, and include, but are not limited to, express or implied statements regarding our current beliefs, expectations and assumptions regarding: our business, future plans and strategies for our CAAR T and CARTA technologies; our ability to grow our autoimmune-focused pipeline; the ability to capitalize on and potential benefits resulting from our research and translational insights; including those related to any similarly-designed constructs or dosing regimens; the anticipated market opportunities for CABA-201 in patients with autoimmune diseases; the Company’s business plans and objectives; our expectations around the potential success and therapeutic benefits of CABA-201, including our belief that CABA-201 may enable an “immune system reset”; Cabaletta's belief of the potential for CAR T to enable a paradigm shift in autoimmunity, including its potential achieve durable remissions without chronic therapy; our plans for Phase 1/2 clinical trials of CABA-201 in patients with systemic lupus erythematosus (SLE), myositis, SSc, and generalized myasthenia gravis (gMG), and for advancement of a RESET-PV sub-study within the ongoing DesCAARTes trial in PV, including the timing thereof, including our anticipated progress, timing of enrollment, expectations for the efficiency of trial designs, updates related to status, safety data, or otherwise and the expected timing of the related data read-outs, and ability to leverage our experience in autoimmune cell therapy; our ability to enroll the requisite number of patients, dose each dosing cohort in the intended manner, and advance the trial as planned in our Phase 1/2 clinical trials of CABA-201; the timing any planned regulatory filings for our development programs, including IND applications; the progress and results of our MusCAARTes™ Phase 1 trial, including the significance and impact around reported safety and clinical and translational data of cohorts from our MusCAARTes™ Phase 1 trial; Cabaletta's potential to eliminate the need for apheresis by using a simpler collection process to obtain the starting material for the CABA-201 manufacturing process the therapeutic potential and clinical benefits of our product candidates; the expectation that Cabaletta may improve outcomes for patients suffering from SLE, SSc, myositis, gMG, mucosal pemphigus vulgaris, MuSK myasthenia gravis, or other autoimmune diseases; the ability of our clinical strategy to reduce risk, maximize reach and accelerate timelines of our Phase 1/2 clinical trials of CABA-201; expectation that clinical results will support CABA-201's safety and activity profile; statements regarding the timing of regulatory filings and interactions with regulatory authorities, including such authorities' review of safety information from our ongoing clinical trials; our ability to successfully complete our preclinical and clinical studies for our product candidates, including our ability to enroll the requisite number of patients, dose each dosing cohort in the intended manner, and progress the trial; our ability to obtain and maintain regulatory approval of our product candidates, including our expectations regarding the intended incentives conferred by and ability to retain Orphan Drug Designation and Fast Track Designations for our product candidates, as applicable; our ability to accelerate our pipeline and to develop meaningful therapies for patients, including in collaboration with academic and industry partners and the ability to optimize such collaborations on our development programs; our ability to contract with third-party suppliers and manufacturers and retain such manufacturers, whether due to legislative action or otherwise; to implement an enhanced manufacturing process and further develop our internal manufacturing strategy, capabilities and facilities; our ability to execute its manufacturing strategy to enable expansion of clinical supply and efficiently scale commercial supply for CABA-201; our potential commercial opportunities, including value and addressable market, for our product candidates; and our expectations regarding our use of capital and other financial results, including our ability to fund operations into the first half of 2026. Words such as, but not limited to, “look forward to,” “believe,” “expect,” “anticipate,” “estimate,” “intend,” “plan,” “would,” “should” and “could,” and similar expressions or words, identify forward-looking statements. Various risks, uncertainties and assumptions could cause actual results to differ materially from those anticipated or implied in our forward-looking statements. Such risks and uncertainties include, but are not limited to, risks related to the success, cost, and timing of our product candidate development activities and preclinical studies and clinical trials, risks related to our ability to demonstrate sufficient evidence of safety, efficacy and tolerability in our preclinical studies and clinical trials of CABA-201 and MuSK-CAART, the risk that the results observed with the similarly-designed construct, including, but not limited to, due to dosing regimen, are not indicative of the results we seek to achieve with CABA-201, the risk that signs of biologic activity or persistence may not inform long-term results, the risk that persistence observed with effective CD19-CAR T oncology studies in combination with lymphodepletion is not indicative of, or applicable to, clinical responses in patients with mPV, risks related to clinical trial site activation or enrollment rates that are lower than expected, our ability to demonstrate sufficient evidence of safety, efficacy and tolerability in its preclinical studies and clinical trials of CABA-201; 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; our ability to protect and maintain our intellectual property position, risks related to our relationships with third parties, uncertainties related to regulatory agencies’ evaluation of regulatory filings and other information related to our product candidates, our ability to retain and recognize the intended incentives conferred by any Orphan Drug Designations and Fast Track Designations, risks related to regulatory filings and potential clearance, the risk that any one or more of our product candidates will not be successfully developed and commercialized, the risk that the results of preclinical studies or clinical studies will not be predictive of future results in connection with future studies, and risks related to volatile market and economic conditions and public health crises. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise. Although we believe the expectations reflected in such forward-looking statements are reasonable, we can give no assurance that such expectations will prove to be correct. Accordingly, you are cautioned not to place undue reliance on these forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ materially from those contained in the forward-looking statements, see the section entitled "Risk Factors" in our most recent annual report on Form 10-K, as well as discussions of potential risks, uncertainties, and other important factors in our other and subsequent filings with the Securities and Exchange Commission. Certain information contained in this Presentation relates to or is based on studies, publications, surveys and other data obtained from third-party sources and the Company’s own internal estimates and research. While the Company believes these third-party sources to be reliable as of the date of this Presentation, it has not independently verified, and makes no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. The Company is the owner of various trademarks, trade names and service marks. Certain other trademarks, trade names and service marks appearing in this Presentation are the property of third parties. Solely for convenience, the trademarks and trade names in this Presentation are referred to without the ® and TM symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.

Develop and launch the first curative targeted cellular therapies for patients with autoimmune diseases

Realizing the vision to transform autoimmune disease treatment 1H24: Reported initial myositis & SLE clinical data at EULAR2 Evaluating CABA-201 without preconditioning Advancing program to potentially eliminate apheresis Securing scalable commercial manufacturing Cash runway into 1H26 Engineered CABA-201 specifically for use in autoimmune patients Leveraging data from an academic 4-1BB CD19-CAR T construct with favorable safety data & durable, drug free remissions1 Executing novel and broad clinical program to accelerate path to approval No requirement for dose escalation Independent, parallel 6-patient cohorts Increasing enrollment at >20 clinical sites 2H24: Additional data from myositis & SLE trials Initial clinical data in SSc & gMG trials FDA fast track designation granted for CABA-201 in multiple indications3 SLE – Systemic lupus erythematosus; SSc – Systemic sclerosis; gMG – Generalized myasthenia gravis Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. The construct utilized in these studies has a similar design to CABA-201, sharing the 4-1BB costimulatory domain, but is a different construct. Data cut-off as of 28 May 2024. FDA Fast Track Designation received in dermatomyositis, SLE, lupus nephritis and systemic sclerosis.

Innovative and scalable clinical strategy with potential for accelerated development path Pipeline targeting autoimmune diseases with high unmet need Program Trial Preclinical Phase 1/2 Pivotal CABA-201 4-1BB CD19-CAR T RESET-Myositis™ CARTA Chimeric Antigen Receptor T cells for Autoimmunity RESET-SLE™ RESET-SSc™ RESET-MG™ RESET-PV™ Sub-study1 CAART Chimeric AutoAntibody Receptor T cells MusCAARTes™ Dermatomyositis Anti-synthetase syndrome IMNM Lupus Nephritis Non-Renal SLE Skin + Organ Cohort AChR-Ab neg. gMG AChR-Ab pos. gMG Skin Cohort Rheumatology Neurology Dermatology FTD Mucocutaneous & mucosal pemphigus vulgaris2 Contains cohort(s) without preconditioning Juvenile Myositis Pediatric Indication MuSK-Ab positive MG2 FTD RESET™ – REstoring SElf-Tolerance; IMNM – Immune-mediated necrotizing myopathy; SLE – Systemic lupus erythematosus; Ab – Antibody; AChR – Acetylcholine receptor; gMG – Generalized myasthenia gravis Sub-study incorporated into DesCAARTes™ study. 2. Currently being evaluated in a Phase 1 trial. FDA Fast Track Designation received in dermatomyositis, SLE and lupus nephritis, systemic sclerosis, mucosal pemphigus vulgaris, and MuSK-Ab positive MG.

Chimeric Antigen Receptor T Cells for Autoimmunity CABA-201

Cabaletta’s CD19 binder with similar in vitro & in vivo activity to FMC631,2 (binder used in academic report3) CABA-201: CD19-CAR T specifically designed for autoimmunity IIT – Investigator-initiated trial; Flu/Cy – Fludarabine/Cyclophosphamide Peng, Binghao J, et al. “Preclinical specificity and activity of CABA-201, a fully human 4-1BB containing CD19 CAR T therapy for treatment-resistant autoimmune disease.” Poster presented at: American Society Gene and Cell Therapy 26th Annual Meeting; 2023 May 19; Los Angeles, CA. Dai, Zhenyu, et al. "Development and functional characterization of novel fully human anti‐CD19 chimeric antigen receptors for T‐cell therapy." Journal of Cellular Physiology 236.8 (2021): 5832-5847. Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. Evaluated as part of CT120, a dual-CD19xCD22 CAR T product candidate under development by Nanjing IASO Biotherapeutics, Co., Ltd. (IASO Bio). Transmembrane domain in CABA-201 is CD8α vs. TNFRSF19 (Troy) utilized in the academic construct. The two transmembrane domains have not been shown to have a significant difference in function or IFN-γ production in preclinical studies. The CD8α transmembrane domain is employed in tisagenlecleucel. CABA-201 Clinical data reported by IASO using licensed CD19 binder in oncology4 Fully human binder Evaluated as dual-CAR combined with CD22 binder with standard Flu/Cy preconditioning Data reported in ~20 patients to date B cell leukemia and lymphoma in IIT in China Safety data supports autoimmune development Fully human anti-CD19 binder Similar binding affinity & biologic activity to FMC63, with binding to the same epitopes1,2 4-1BB costimulatory domain Same co-stim. domain as used in academic studies CD3-zeta signaling domain CABA-2015

SLE & myositis trials currently enrolling, with a broadening portfolio to realize the potential of CABA-201 REstoring SElf-Tolerance (RESET™) Phase 1/2 trials advancing SLE – Systemic lupus erythematosus; DM – Dermatomyositis; SSc – Systemic sclerosis; gMG – Generalized myasthenia gravis; ESRD – End-stage renal disease CABA-201 also to be evaluated in the absence of preconditioning in pemphigus vulgaris sub-study CABA-201 SSc gMG 2024 ~88k ~55k Over 1 million Middle age onset common Progressive skin & organ fibrosis with lung, cardiac, renal damage Average survival of 12y Bimodal age of onset Profound weakness that can be disabling Risk for myasthenic crises, with respiratory failure Phase 1/2 Trials Rheum Neuro Undiscl. U.S. Prevalence Preclinical Autoimmune diseases in which B cells play a key role SLE ~160-320k Affects young women & people of color ~40% with lupus nephritis, which carries ~25% risk of death or ESRD within 10y > > > Myositis ~68k Typical onset middle age Only FDA-approved therapy is IVIg in DM High mortality due to lung & cardiac involvement >

Broad investigation of CABA-201 in well-defined patient populations with the same dose & similar design Clinical strategy to reduce risk, maximize reach & accelerate timelines SLE – Systemic lupus erythematosus; SSc – Systemic sclerosis; gMG – Generalized myasthenia gravis; ASyS – Anti-synthetase syndrome; DM – Dermatomyositis; IMNM – Immune-mediated necrotizing myopathy Subjects will be treated with a standard preconditioning regimen consisting of fludarabine and cyclophosphamide prior to a single dose CABA-201, followed by short inpatient stay. The data reported in the academic literature does not employ CABA-201. Each cohort to include 6 patients treated with an identical dose – without dose escalation requirement – and designed to inform discussions with FDA on registrational path for each indication CABA-201 ASyS Cohort Single infusion1 CABA-201 IMNM Cohort Single infusion1 DM Cohort CABA-201 Skin + Organ Involvement Cohort CABA-201 AChR+ gMG Cohort CABA-201 Lupus Nephritis Cohort CABA-201 Non-renal SLE Cohort Severe Skin Involvement Cohort AChR- gMG Cohort CABA-201 CABA-201 CABA-201 No CD19-CAR T clinical data CD19-CAR T clinical data reported in academic literature2 Single infusion1 Single infusion1 Single infusion1 Single infusion1 Single infusion1 Single infusion1 Single infusion1 CABA-201 Juvenile myositis cohort recently incorporated into trial

Initial data presented at EULAR 2024 Congress; enrolling patients with active myositis with DM, ASyS or IMNM RESET-Myositis™: Phase 1/2 study design for CABA-201 IIM – Idiopathic inflammatory myopathy; DM – Dermatomyositis; ASyS – Anti-synthetase syndrome; IMNM – Immune-mediated necrotizing myopathy; CK – creatine kinase Subjects will be treated with a standard preconditioning regimen consisting of fludarabine and cyclophosphamide prior to a single dose CABA-201, followed by short inpatient stay. Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. CABA-201 ASyS B cell-depleting agent within prior ~6 months Primary objective Safety & tolerability within 28 days of infusion Categories of key secondary objectives Myositis clinical activity CK / muscle enzymes Myositis-specific autoantibody levels Adverse events PK / PD analysis Open-label trial with parallel 6-subject cohorts Equivalent to dose of 4-1BB CD19-CAR T used in academic report along with standard preconditioning1,2 Screening Study Objectives Phase 1/2 Study Design Evidence of active disease despite standard of care Key inclusion criteria Cancer associated myositis Key exclusion criteria Significant lung or cardiac impairment Adults 18-75y with a clinical IIM diagnosis Single dose of 1x106 cells/kg1 CABA-201 Single dose of 1x106 cells/kg1 CABA-201 Single dose of 1x106 cells/kg1 CABA-201 DM IMNM Previous CAR T cell therapy and/or HSCT Subtype based on serology Juvenile idiopathic inflammatory myopathy (JIIM, juvenile myositis) cohort recently incorporated into trial

Initial data presented at EULAR 2024 Congress; enrolling patients with active SLE with or without renal disease RESET-SLE™: Phase 1/2 study design for CABA-201 SLE – Systemic lupus erythematosus; SSc – Systemic sclerosis; gMG – Generalized myasthenia gravis Subjects will be treated with a standard preconditioning regimen consisting of fludarabine and cyclophosphamide prior to a single dose CABA-201, followed by short inpatient stay. Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. CABA-201 SLE with lupus nephritis SLE without renal disease Open-label trial with parallel 6-subject cohorts Equivalent to dose of 4-1BB CD19-CAR T used in academic report along with standard preconditioning1,2 Screening Study Objectives Phase 1/2 Study Design Similarly designed Phase 1/2 trials – RESET-SSc™ & RESET-MG™ – advancing in SSc & gMG Confirmatory serology B cell-depleting agent within prior ~6 months SLE: active, moderate to severe SLE, SLEDAI 2K ≥8 despite standard therapy Key inclusion criteria Presence of kidney disease other than LN Key exclusion criteria Single dose of 1x106 cells/kg1 CABA-201 Single dose of 1x106 cells/kg1 CABA-201 Adults 18-65y with an SLE diagnosis Primary objective Safety & tolerability within 28 days of infusion Categories of key secondary objectives SLE disease activity Complete renal response Adverse events PK / PD analysis Biomarker analyses LN: active, biopsy-proven LN class III or IV, ± class V Previous CAR T cell therapy and/or HSCT

Evaluating CABA-201 without preconditioning in pemphigus DSG – Desmoglein; PV – Pemphigus vulgaris Cohen, Adam D., et al. "B cell maturation antigen–specific CAR T cells are clinically active in multiple myeloma." The Journal of Clinical Investigation 129.6 (2019). Schmidt, Enno, et al. "Novel ELISA systems for antibodies to desmoglein 1 and 3." Experimental dermatology 19.5 (2010): 458-463. CABA-201 Published data in multiple myeloma suggests preconditioning may not be necessary1 Experience with and without preconditioning in PV in DesCAARTes™ study Open-label umbrella trial incorporating CABA-201 into DSG3-CAART study Updated PV Study Design Mucocutaneous & mucosal PV Initiating sub-study without preconditioning CABA-201 New sub-study As a well-defined autoantibody-mediated disease, PV is a potentially ideal evaluation setting Anti-DSG antibodies necessary & sufficient for disease Anti-DSG antibodies 98-100% sensitive & specific2 Anti-DSG antibodies correlate with disease activity Depletion of B cells or antibodies improve disease Clinical scoring based on mucosal & skin disease Elimination of preconditioning may expand CAR T opportunity for autoimmune patients Dose-ranging cohorts in absence of preconditioning DSG3-CAART Mucosal PV Combination with IVIg & CY Mucosal PV Combination with IVIg, CY & fludarabine Mucosal PV Enrollment completed

Time to B cell repopulation B cell phenotype3 Autoantibody changes Durability of clinical activity Rate & severity of infection Delayed cytopenias Chronic maintenance / concomitant medications, if any Up to 12+ months Translational & clinical parameters inform framework to evaluate advanced modalities in autoimmunity Metrics to assess outcomes of B cell depletion in autoimmunity Indicates data presented at EULAR 2024 for either or both of the first two patients in the RESET clinical program. Illustrative graphic, adapted from Taubmann, J., et al. "OP0141 Long Term Safety and Efficacy Of CAR-T Cell Treatment in Refractory SLE-Data from the First Seven Patients." (2023): 93-94. Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. Flow phenotyping data; confirmatory analyses ongoing. Following treatment with autologous CD19-CAR T, 6 pts with 12+ mo. of drug-free remission, as reported by Erlangen group2 Infusion 1 mo. 3 mo. 12+ mo. 6 mo. CD19-CAR T Cells Naïve B cells Healthy B cells Autoreactive B cells CAR T & B cell levels1 Translational measures Clinical data Patient experience B cell depletion: Timing & depth CAR T expansion: Magnitude & timing Rate of CRS more severe than fever Rate & grade of ICANS Rate & severity of infection Hospitalization requirements Apheresis & preconditioning Single vs. multiple infusions Autoantibody changes Vaccine titer changes Inflammatory marker changes Early efficacy signals Rate & severity of infection Chronic maintenance therapy / concomitant medications, if any Within 1 month ~3 months Metrics of evaluation

CABA-201 exhibited anticipated profile of expansion and contraction1 CABA-201 demonstrated expansion & targeted B cell depletion Response appears to be consistent with published data of cryopreserved CAR T products as well as the expansion profile of BCMA-CAR T products in patients with multiple myeloma, in which the number of target cells is more similar to autoimmune disease than to B cell leukemias and lymphomas.2-6 Shah BD, et al. Lancet. 2021;398(10299):491-502. Awasthi R, et al. Blood Adv. 2020;4(3):560-572. IMNM #1 SLE #1 Expansion of CAR T cells to anticipated range suggests target engagement Complete B cell depletion achieved by day 15 on flow cytometry Peripheral peak CAR T expansion occurred at approximately 2 weeks & rapid contraction suggests systemic B cell aplasia was achieved 4.98% of T cells 3.32% of T cells CABA-201 cells/µL Blood 102 101 100 0 −5 0 5 10 15 20 25 30 Days post infusion SLE #1 IMNM #1 Preconditioning CABA-201 infusion CD19+ CD20+ B cells/µL 60 80 60 20 0 −5 0 5 10 15 20 25 30 Days post infusion Munshi NC, et al. N Engl J Med. 2021;384(8):705-716. Cohen AD, et al. Blood Cancer J. 2022;12(2):32. Müller F, et al. N Engl J Med. 2024;390(8):687-700.

Antibody reduction & clinical improvement in disease activity observed with follow-up of 12 weeks1 CK reduction & clinical improvement observed in SRP IMNM Data cut-off as of May 28, 2024. Luminex assay developed and performed by Cabaletta Labs. Qualitative commercial assay (Myositis Antigen Panel, performed at National Jewish Health Advanced Diagnostic Laboratories) suggests SRP54 antibody remains strongly positive at Week 12; Ro-52 normalizes by week 8. Based on patient’s moderate level of muscle disease at baseline, mild-moderate disability and limited extramuscular manifestations, the maximum achievable score is 70 points on the 100-point TIS scale. Patient treated in third-party CASTLE Phase I/II basket study, TIS data at Week 12 and 24 provided via personal communication with and as presented by Dr. Georg Schett at the EULAR 2024 symposium. Müller F, et al. N Engl J Med. 2024;390(8):687-700. IMNM #1 Discontinued all disease-specific therapies Disease markers continuing to trend positively Patient reported symptoms as much improved Disease activity & improvement measures Quantitative translational assay shows ongoing reduction in SRP & Ro-52 antibodies2,3 12-week TIS consistent with IMNM case report5 Baseline Week 4 ULN U/L 600 400 200 0 Week 8 Week 12 Creatine Kinase Normal strength MMT-8 150 140 130 120 Baseline Week 4 Week 8 Week 12 Score Major Score (points) 100 80 Minor Moderate 60 40 20 Week 24 Baseline Week 12 None RESET-Myositis IMNM #1 patient-specific TIS ceiling4 TIS RESET-Myositis IMNM #1 patient treated with CABA-201 IMNM patient in CASTLE basket study5 ASyS patients treated at Univ. Hospital Erlangen via German expanded access program6 Academic published data overlaid for illustrative purposes SRP9 SRP54 SS-A/Ro-52 Week 8 Week 4 Baseline 10000 5000 0 Week 8 Week 4 Baseline 1500 500 2000 Week 12 1000 0 Net MFI Net MFI SRP No CRS, ICANS, or infections reported (no tocilizumab received), and the SRP IMNM patient was discharged 4 days post infusion

0 0 Month 3 Month 6 SLEDAI-2K Score 25 20 30 10 5 15 Academic published data for illustrative purposes Trend toward improvement in disease manifestations observed with follow up of 4 weeks2 Early efficacy signals in first patient in non-renal SLE cohort1 Patient in non-renal SLE cohort due to isolated Class V LN. Data cut-off as of 28 May 2024. Baseline and Day 29 SLEDAI-2K score are reflective of disease activity at study visit day. SLE #1 Vasculitis, arthritis and hematuria resolved within 4 weeks despite discontinuation of all therapies at infusion other than ongoing taper from prednisone 10mg per day Alopecia Low complement Increased DNA binding4 Proteinuria5 Hematuria Arthritis Vasculitis 26 10 20 SLEDAI-2K3 10 0 Baseline Week 4 30 SLE patient #1 Academic SLE data6 4. Anti-dsDNA antibody titer decreased from 1:40 to 1:10 from Baseline to Week 4. 5. Urine Protein Creatinine Ratio decreased from 1.08 to 0.80 from Baseline to Week 4. 6. SLE patients treated at Univ. Hospital Erlangen via German expanded access program; Müller F, et al. N Engl J Med. 2024;390(8):687-700. No CRS, ICANS, or infections reported (no tocilizumab received), and the non-renal SLE patient was discharged 4 days post infusion

BAFF B cells Preconditioning CABA-201 infusion Initial patient phenotyping data consistent with potential immune system reset; confirmatory analyses ongoing Naïve B cell repopulation occurred at 2 months in first IMNM patient Note: Flow plot gating reflects CD19+ CD20+ live lymphocytes. Data cut-off as of May 28, 2024. Systemic B cell depletion triggers BAFF to encourage bone marrow B cell repopulation IMNM #1 15000 10000 5000 0 0 25 50 Days post infusion CD19+ CD20+ B cells/µL BAFF (pg/mL) 80 60 40 20 0 B Cell, % CD20 Baseline CD19 107 106 105 104 0 0 104 106 105 B cells (CD19+, CD20+) 5.08 Week 12 107 106 105 104 0 0 104 106 105 B cells (CD19+, CD20+) 6.56 107 Day 15 107 106 105 104 0 0 104 106 105 B cells (CD19+, CD20+) 0 Week 8 107 106 105 104 0 0 104 106 105 B cells (CD19+, CD20+) 7.02 CD38 CD24 106 105 104 0 0 104 106 105 106 105 104 0 0 104 106 105 106 105 104 0 0 104 106 105 B cell phenotyping data 1 Early Naïve (Transitional) B cell Naïve B cell Remaining CD19+ CD20+ B cells

Staged approach allows for efficient allocation of capital while leveraging experienced partners Manufacturing strategy Late Phase & Commercial: Scale-Up & Commercialization Data-gated, staged investment Early Phase: Penn, CDMOs & CABA Process Ongoing Penn has reliably provided timely product for years Expanded commercial CDMO partnerships for vector and cell product supply Process development work on track to implement commercial-ready process in pivotal studies Evaluating paths to commercial-ready manufacturing: Expansion of CDMO relationships Opportunities for automated manufacturing Cabaletta-operated facility Strategic partnership(s) Continuous focus on innovations to address scale Internal program Cellares technology assessment program advancing

Securing & expanding our leadership in autoimmune cell therapy Myositis Systemic lupus erythematosus Systemic sclerosis Generalized myasthenia gravis Pemphigus vulgaris Minimizing the requirement for inpatient stay Evaluating CABA-201 without preconditioning Seeking to remove the burden of apheresis1 Innovating to address scale in autoimmune disease Immune thrombocytopenic purpura Thrombotic thrombocytopenic purpura Antiphospholipid syndrome Autoimmune hemolytic anemia Hematology Type 1 diabetes Graves’ disease Hashimoto’s disease Endocrinology Rheumatology Rheumatoid arthritis ANCA-associated vasculitis Sjögren’s syndrome Neurology Multiple sclerosis Neuromyelitis optica CIDP Nephrology Membranous nephropathy Goodpasture’s syndrome Dermatology Pemphigus foliaceus Epidermolysis bullosa acquisita Bullous pemphigoid Increased enrollment since EULAR presentation Broadening potential to serve patients Biologic opportunity for potential cure or paradigm-shifting treatment may be possible in dozens of autoimmune diseases Advancing the RESET™ clinical trials with the goal of delivering on our commitment to patients 1. Abstract 1372: Autologous CD19 CART Manufacturing from Whole Blood Collection for the Treatment of Autoimmune Disease. ASGCT 2024.

Corporate Summary

Track record of operational success evaluating novel cell therapy candidates in autoimmunity Cabaletta Bio leadership LEADERSHIP TEAM Anup Marda Chief Financial Officer Arun Das, M.D. Chief Business Officer David J. Chang, M.D., M.P.H., FACR Chief Medical Officer Martha O’Connor Chief HR Officer Michael Gerard General Counsel Steven Nichtberger, M.D. President, CEO & Chairman Heather Harte-Hall Chief Compliance Officer Samik Basu, M.D. Chief Scientific Officer Gwendolyn Binder, Ph.D. President, Science & Technology SCIENTIFIC ADVISORY BOARD Aimee Payne, M.D., Ph.D. Co-Founder and Co-Chair Michael C. Milone, M.D., Ph.D. Co-Founder and Co-Chair Carl June, M.D. Jay Siegel, M.D. Brian Daniels, M.D. Drew Weissman, M.D., Ph.D. Iain McInnes, Ph.D., FRCP, FRSE, FMedSci Georg Schett, M.D. BOARD OF DIRECTORS Steven Nichtberger, M.D. Richard Henriques Scott Brun, M.D. Mark Simon Catherine Bollard, M.D. Shawn Tomasello From Fortune. ©2023 Fortune Media IP Limited. All rights reserved. Used under license. Sarah Yuan Chief Technology Officer

Realizing the vision to transform autoimmune disease treatment 1H24: Reported initial myositis & SLE clinical data at EULAR2 Evaluating CABA-201 without preconditioning Advancing program to potentially eliminate apheresis Securing scalable commercial manufacturing Cash runway into 1H26 Engineered CABA-201 specifically for use in autoimmune patients Leveraging data from an academic 4-1BB CD19-CAR T construct with favorable safety data & durable, drug free remissions1 Executing novel and broad clinical program to accelerate path to approval No requirement for dose escalation Independent, parallel 6-patient cohorts Increasing enrollment at >20 clinical sites 2H24: Additional data from myositis & SLE trials Initial clinical data in SSc & gMG trials FDA fast track designation granted for CABA-201 in multiple indications3 SLE – Systemic lupus erythematosus; SSc – Systemic sclerosis; gMG – Generalized myasthenia gravis Müller, Fabian, et al. "CD19 CAR T-Cell Therapy in Autoimmune Disease—A Case Series with Follow-up." New England Journal of Medicine 390.8 (2024): 687-700. The construct utilized in these studies has a similar design to CABA-201, sharing the 4-1BB costimulatory domain, but is a different construct. Data cut-off as of 28 May 2024. FDA Fast Track Designation received in dermatomyositis, SLE, lupus nephritis and systemic sclerosis.

Corporate Presentation AUGUST 2024

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