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

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 provided a business update.

The DesCAARTes trial is continuing to advance through additional cohorts including higher

doses as well as a planned combination cohort with intravenous immunoglobulin and cyclophosphamide administered prior to DSG3-CAART infusion, which are expected to start dosing following cohort A5. We also expect to present 6 month clinical and

translational data from cohort A4 as well as 28-day safety data from cohort A5 at the upcoming European Association of Dermatology and Venereology Congress next month, said Steven Nichtberger, M.D.,

Chief Executive Officer and Co-founder of Cabaletta. With cash on hand to fund operations through the first quarter of 2024, the goal of our autoimmune-focused pipeline is to achieve deep, durable and

perhaps curative outcomes for patients. We are confident that we are well-positioned to build on our progress to date and deliver long-term value to patients and our other key stakeholders.

Pipeline Highlights and Anticipated Upcoming Milestones

DSG3-CAART: Desmoglein 3 chimeric autoantibody receptor T (DSG3-CAART) cells as a potential treatment for patients with mucosal pemphigus vulgaris

MuSK-CAART: Muscle-specific kinase (MuSK) chimeric autoantibody receptor T (MuSK-CAART) cells

as a potential treatment for patients with MuSK-associated myasthenia gravis.

Cabaletta will participate in the following upcoming investor conferences:

Second Quarter 2022 Financial Results

Based on updated forecasting, the Company expects that its cash, cash equivalents and

investments as of June 30, 2022 will enable it to fund its operating plan through the first quarter of 2024.

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, in combination with Cabaletta Bio s proprietary

technology, has advanced a growing pipeline that currently includes potential treatments for patients with mucosal pemphigus vulgaris, MuSK-associated myasthenia gravis, PLA2R-associated membranous nephropathy, mucocutaneous pemphigus vulgaris and

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 expectations regarding:

Cabaletta s ability to grow and advance its autoimmune-focused and preclinical pipeline; the progress and results of its DesCAARTes Phase 1 trial and planned MusCAARTes trial, including its ability to enroll the requisite number of patients, dose each dosing cohort in the intended manner, and progress the trial; the significance and impact around the clinical

and translational data updates from cohorts A1 through A3 of the DesCAARTes trial; the expected timing and significance of the announcement of 28-day

safety for cohort A5 and clinical and translational data for cohort A4 at the 31st EADV Congress in September 2022; the expectation that Cabaletta may improve outcomes for patients suffering from

mPV; Cabaletta s ability to escalate dosing as high as 10 to 15 billion cells in a planned future cohort, initiate dosing in a combination cohort or otherwise; Cabaletta s plans to implement a

pre-treatment regimen; Cabaletta s ability to advance dose escalation in the DesCAARTes Phase 1 trial at the current dose ranges for the current

cohorts and any projected potential dose ranges for future cohorts, and to optimize its targeted cell therapy; Cabaletta s ability to evaluate, and the potential significance of, the relationship between DSG3-CAART persistence and potential

clinical responses in patients with mPV; the expectation that Cabaletta Bio may improve outcomes for patients suffering from MuSK MG; plans to initiate patient dosing in an open-label Phase 1 clinical trial to evaluate MuSK-CAART safety and

tolerability in MuSK MG patients in 2022; the effectiveness and timing of product candidates that Cabaletta may develop, including in collaboration with academic partners; presentation of additional data at upcoming scientific conferences, and other

preclinical data; expectations regarding the design, implementation, timing and success of its current and

planned clinical trials and the successful completion of nonclinical studies; planned potential timing and advancement of its preclinical studies and clinical trials and related regulatory

submissions; ability to optimize the impact of its collaborations on its development programs; use of capital, expenses, future accumulated deficit and other financial results in the future; and ability to fund operations through the first quarter

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:

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 and clinical trials of DSG3-CAART and

MuSK-CAART; the risk that persistence observed with effective CART-19 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; risks related to unexpected safety or efficacy data observed during clinical studies; risks related to the impact of public health epidemics, such as the

ongoing COVID-19 pandemic, affecting countries or regions in which we have operations or do business; Cabaletta s ability to retain and recognize the intended incentives conferred by Orphan Drug

Designation and Fast Track Designation for DSG3-CAART for improving healing of mucosal blisters in patients with mucosal pemphigus vulgaris; Cabaletta s ability to demonstrate sufficient evidence of safety, efficacy and tolerability in its

preclinical and clinical trials of DSG3-CAART and MuSK-CAART; risks related to fostering and maintaining successful relationships with Cabaletta s manufacturing partners; risks related to Cabaletta s ability to protect and maintain its

intellectual property position; 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 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.

SELECTED FINANCIAL DATA

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

Statements of Operations

Selected Balance Sheet Data

Chief Financial Officer

Stern Investor Relations, Inc.