Cabaletta Bio, Inc.

Notes to the Consolidated Financial Statements

1. Basis of Presentation

Cabaletta Bio, Inc. (the Company or Cabaletta) was incorporated in April 2017 in the State of Delaware as Tycho Therapeutics, Inc. and, in August 2018, changed its name to Cabaletta Bio, Inc. The consolidated financial statements include the accounts of Cabaletta Bio and its wholly owned subsidiaries: Cabaletta Bio GmbH and Cabaletta Bio (Germany) GmbH. All intercompany balances and transactions have been eliminated in consolidation.

The Company is headquartered in Philadelphia, Pennsylvania. Cabaletta is a clinical-stage biotechnology company focused on the discovery and development of engineered T cell therapies for autoimmune diseases. Principal operations commenced in April 2018.

Risks and Uncertainties

The Company does not expect to generate revenue from sales of engineered T cell therapies for autoimmune diseases or any other revenue unless and until the Company completes preclinical and clinical development and obtains regulatory approval for one or more product candidates. If the Company seeks to obtain regulatory approval for any of its product candidates, the Company expects to incur significant commercialization expenses.

The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. As a result, the Company is unable to predict the timing or amount of increased expenses or when or if the Company will be able to achieve or maintain profitability. Further, the Company is dependent on third parties for certain research and development activities, including manufacturing services (Note 6 and Note 7). Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. Even if the Company is able to generate revenues from the sale of its product candidates, if approved, it may not become profitable. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations.

Liquidity and Going Concern

In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, ("ASC 205-40") the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern. The Company has sustained annual operating losses since inception and expects to continue to generate operating losses for the foreseeable future. As of December 31, 2024, the Company has incurred an accumulated deficit of$349,101 and has a cash and cash equivalents balance of $163,962. The Company’s ultimate success depends on the outcome of its research and development activities. Management expects to incur additional losses in the future as it continues its research and development and will need to raise additional capital to fully implement its business plan and to fund its operations. The Company intends to raise such additional capital through a combination of equity offerings, debt financings, government funding arrangements, strategic alliances or other sources. However, if such financing is not available at adequate levels and on a timely basis, or such agreements are not available on favorable terms, or at all, as and when needed, the Company will need to reevaluate its operating plan and may be required to delay or discontinue the development of one or more of its product candidates or operational initiatives. The Company expects that its current cash and cash equivalents may not be sufficient to fund operations for at least the next twelve months from the date of issuance of these consolidated financial statements. The Company's cash forecast contains estimates and assumptions based on success of ongoing clinical trials, and management cannot predict the amount or timing of all expenditures with certainty. Accordingly, the Company has concluded that substantial doubt exists about the Company’s ability to continue as a going concern. The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business.

2. Summary of Significant Accounting Policies

Principles of Consolidation

The accompanying consolidated financial statements included herein have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP") and under the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include but are not limited to advance payments and accruals related to the Company’s research and development expenses. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.

Off-Balance Sheet Risk and Concentrations of Credit Risk

Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist of cash and cash equivalents, which are invested in U.S. treasury-based money market funds. As of December 31, 2023, the Company held available-for-sale securities, which were invested in U.S. treasury securities. These investments matured in 2024. A portion of the Company’s cash is maintained at two federally insured financial institutions, and account balances may at times exceed federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk. The Company has no off‑balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements.

The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts.

Investments

Investments are available-for-sale and carried at estimated fair value. The Company’s valuations of available-for-sale debt securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. Management determines the appropriate classification of its investments in debt securities at the time of purchase and at the end of each reporting period. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than, twelve months from the balance sheet date are classified as current.

Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive income. The Company periodically evaluates whether declines in fair values of its available-for-sale securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors including the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or if more likely than not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. Realized gains and losses and declines in fair value judged to be other-than-temporary, if any, on available-for-sale securities are included in interest and other income, net. The cost of investments sold is based on the specific-identification method. Interest income on investments as well as amortization of discount or premium is included in interest income.

Property, Plant and Equipment

Property, plant and equipment are recorded at cost less accumulated depreciation. Cost includes the acquisition costs and all costs necessary to bring the asset to the location and working condition necessary for its intended use. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the accompanying statements of operations. Expenditures for normal, recurring or periodic repairs and maintenance related to property and equipment are charged to expense as incurred. The cost for planned major maintenance activities, including the related acquisition or construction of assets, is capitalized if it will result in future economic benefits.

Estimated useful lives for property and equipment are as follows:

Fair Value Measurement

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Leases

The Company has leases related to its facilities used for offices and laboratory space, which are classified as operating leases as well as leases related to its manufacturing arrangements, which are classified as finance leases.

At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease and its classification based on the unique facts and circumstances present in the arrangement. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets and current and non-current lease liabilities, as applicable.

Lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments. Subsequent to the initial measurement, the Company will continue to account for:

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the lease liability at the net present value using the incremental borrowing rate that was in effect as of the lease commencement, lease modification, or transition date, and;

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the finance lease and operating lease expense on a straight line basis.

Leases with terms of 12 months or less are considered short-term leases and right-of-use assets and lease obligations are not recognized. Payments associated with short-term leases are expensed on a straight-line basis over the lease term.

In accordance with ASC 842, components of a lease should be split into three categories: lease components, non-lease components and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) must be allocated based on the respective relative fair values to the lease components and non-lease components. Entities may elect not to separate lease and non-lease components. Rather, entities would account for each lease component and related non-lease component together as a single lease component. The Company has elected to aggregate all lease and non-lease components for each class of underlying assets into a single lease component for real-estate leases and embedded manufacturing arrangements.

ASC 842 allows for the use of judgment in determining whether the assumed lease term is for a major part of the remaining economic life of the underlying asset and whether the present value of lease payments represents substantially all of the fair value of the underlying asset. The Company applies the guidance in ASC 842-10-55-2 to assist in determining lease classification across its leases.

Research and Development Expenses

Research and development costs include costs incurred for internal and external research and development activities and are expensed as incurred in the accompanying statements of operations. Research and development costs consist of salaries and benefits, including associated stock-based compensation, and laboratory supplies and facility costs, as well as fees paid to entities that conduct certain research and development and clinical trial activities on the Company’s behalf.

The Company records accrued liabilities for estimated costs of research and development activities conducted by service providers, which include preclinical studies, contract manufacturing activities and clinical trial activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided and in accordance with agreements established with service providers and includes these costs in accrued and other current liabilities in the accompanying balance sheets and within research and development expense in the accompanying statements of operations. Non-refundable advance payments made for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as expense as the goods are received or the related services are rendered. The Company makes significant judgments and estimates in determining the accrued liabilities and prepaid expenses in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities and prepaid expenses. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception.

Stock-based Compensation

The Company measures its stock-based awards granted to employees and non-employees based on the estimated fair values of the awards on the respective grant dates. The Company uses the Black-Scholes option-pricing model (Black-Scholes) to estimate the fair value of its stock-based awards. The Company recognizes compensation expense for time-based awards on a straight-line basis over the requisite service period, which is generally the vesting period of the award. The Company accounts for forfeitures of stock option awards as they occur.

Income Taxes

The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax base, as well as for net operating loss carryforwards and research and development credits, and are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.

Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, the Company concludes that it is more-likely-than-not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. Because of the uncertainty of the realization of deferred tax assets, the Company has recorded a full valuation allowance against its deferred tax assets.

Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more-likely-than-not to be sustained on examination by a taxing authority, assuming they possess full knowledge of the position and facts. Interest and penalties related to uncertain tax positions are recognized in the provision of income taxes; however, the Company currently hasno interest or penalties related to uncertain income tax benefits.

Net Loss Per Share

The Company calculates basic and diluted net loss per share in conformity with the two-class method required for participating securities because the Company had both voting and non-voting common stock outstanding in 2023 and for a portion of 2024. The rights, including the liquidation and dividend rights, of the holders of the voting and non-voting common stock are identical, except with respect to voting. Each share of non-voting common stock may be converted at any time into one share of voting common stock at the option of its holder by providing written notice to the Company, subject to the limitations provided for in the amended and restated certificate of incorporation. As of December 31, 2024, no shares of non-voting common stock remain outstanding.

Basic net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted average number of shares of common stock, including any pre-funded warrants to purchase shares of common stock that may be outstanding. The undistributed loss for each year is allocated to common stockholders based on the contractual participation rights of the voting and non-voting common stock as if the losses for the year had been distributed. As the liquidation and dividend rights are identical, the undistributed losses are allocated on a proportionate basis. Diluted net loss per share attributable to common stockholders is computed under the if-converted method and assumes that all non-voting common stock has been converted to common stock. Since the Company was in a loss position for all periods presented, the effects of the other potentially dilutive securities are antidilutive.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (CODM) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer (CEO). The Company has determined it operates in asingle operating segment and hasone reportable segment. Refer to Note 8 – Segment Reporting for further information related to our segment.

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated.

After consummation of the equity financing, these costs are recorded as a reduction to the carrying value of stockholders’ equity as a reduction of additional paid-in capital or equity generated as a result of such offering. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss.

Emerging Growth Company Status

Prior to December 31, 2024, the Company was an “emerging growth company” (EGC) as defined in the Jumpstart Our Business Startups Act, (JOBS Act), and elected to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies until the Company no longer qualifies as an EGC, including using the extended transition period for complying with new or revised accounting standards. As of December 31, 2024, the Company ceased to qualify as an EGC.

Recently Adopted Accounting Pronouncements

In November 2023, the FASB issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures. This ASU requires that a public entity provide additional segment disclosures on an interim and annual basis. The amendments in this ASU should be applied retrospectively to all prior periods presented in the consolidated financial statements, unless impracticable. Upon transition, the segment expense categories and amounts disclosed in the prior periods should be based on the significant segment expense categories identified and disclosed in the period of adoption. The Company adopted this ASU for the annual period ended December 31, 2024 and the amendments have been applied retrospectively to all prior periods presented in the financial statements. Refer to Note 8 – Segment Reporting for further information related to our segment.

Recently Issued Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures. ASU 2023-09 enhances the transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is effective for public business entities for annual periods beginning after December 15, 2024. Early adoption is permitted. This update is effective beginning with the Company’s 2025 fiscal year annual reporting period. The Company is currently planning to adopt this guidance when effective and is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes.

In November 2024, the FASB issued ASU 2024-03, Income Statement (Subtopic 220-40): Reporting Comprehensive Income-Expense Disaggregation Disclosures. ASU 2024-03 requires enhanced disclosures about components of expense captions on the face of the income statement. This standard will be effective for fiscal years beginning after December 15, 2026. Early adoption is permitted. ASU 2024-03 applies on a prospective basis for periods beginning after the effective date. However, retrospective application to any or all prior periods presented is permitted. The Company is currently planning to adopt this guidance when effective and is assessing the impact of the adoption on the Company’s consolidated financial statements and accompanying footnotes.

There have been no other new accounting pronouncements or changes to accounting pronouncements that, if adopted, would have or may have a material impact on the Company’s consolidated statements or disclosures.

3. Fair Value Measurements

As of December 31, 2024 and 2023, the Company’s financial instruments included cash and cash equivalents, available-for-sale debt securities, accounts payable and accrued expenses. The carrying amounts for cash and cash equivalents, accounts payable and accrued expenses reported in the Company’s consolidated financial statements for these instruments approximate their respective fair values because of the short-term nature of these instruments.

The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:

Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as Level 1. Investments are measured at fair value based on inputs other than quoted prices that are derived from observable market data and are classified as Level 2 inputs.

For debt securities classified as available-for-sale investments, the Company records unrealized gains or losses resulting from changes in fair value between measurement dates as a component of other comprehensive income. The Company did not hold any available-for-sale securities as of December 31, 2024:

4. Property, Plant and Equipment

Property, plant and equipment consists of the following:

Depreciation expense was $1,711 and $1,426 for the years ended December 31, 2024 and 2023, respectively.

5. Accrued and Other Current Liabilities

Accrued and other current liabilities consist of the following:

6. Collaborations, Licensing Agreements and other Agreements

Amended and Restated License Agreement with the Trustees of the University of Pennsylvania and Children’s Hospital of Philadelphia

In August 2018, the Company entered into a license agreement with Penn, as amended and restated in July 2019 to include the Children’s Hospital of Philadelphia (CHOP) as a party, and as amended in May 2020 and October 2021 (the License Agreement) pursuant to which the Company obtained (a) a non-exclusive, non-sublicensable worldwide license to certain of Penn’s intellectual property to conduct research, product development, clinical trials, cell manufacturing and other activities, and (b) an exclusive, worldwide, royalty-bearing right and license, with a right to sublicense, on a target-by-target basis, under certain of Penn’s intellectual property to make, use, sell, offer for sale, import, and otherwise commercialize products for the treatment of autoimmune and alloimmune diseases. Unless earlier terminated, the License Agreement expires on the expiration or abandonment or other termination of the last valid claim in Penn’s intellectual property licensed by the Company. The Company may terminate the License Agreement at any time for convenience upon 60 days' written notice. In the event of an uncured, material breach, Penn may terminate the License Agreement upon 60 days' written notice. Under the terms of the License Agreement, the Company was obligated to pay $2,000 annually forthree years beginning August 2018 for funding to the laboratories of each of Drs. Milone and Payne. This was satisfied through completed sponsored research agreements with a total cost of $12,560. During the term of the License Agreement until the first commercial sale of the first product, the Company is obligated to pay Penn a non-refundable, non-creditable annual license maintenance fee of $10. In May 2020, the Company paid Penn an additional, non-refundable, non-creditable license fee of $33 under the amended License Agreement.

The Company is required to pay certain milestone payments upon the achievement of specified clinical and commercial milestones. Milestone payments are reduced by a certain percentage for the second product that achieves a milestone, by an additional percentage for the third product that achieves a milestone, and so on, for each subsequent product that achieves a milestone. In the event that the Company is able to successfully develop and launch multiple products under the License Agreement, total milestone payments could be approximately $21,000. Penn is also eligible to receive tiered royalties at percentage rates in the low single-digits, subject to an annual minimum royalty, on annual worldwide net sales of any products that are commercialized by the Company or its sublicensees that contain or incorporate, or are covered by, the intellectual property licensed by the Company. To the extent the Company sublicenses its license rights under the License Agreement, Penn would be eligible to receive tiered sublicense income at percentage rates in the mid-single to low double-digits. There wereno amounts due under the License Agreement as of December 31, 2024.

Master Translational Research Services Agreement

In October 2018 and February 2023, the Company entered into services agreements (the CAART and CARTA Services Agreements) with Penn for research, development and manufacturing services from various laboratories within Penn. The activities are detailed in separately executed Penn organization-specific addenda. In May 2020, the Company amended its Addendum with the Center for Advanced Retinal and Ocular Therapeutics (CAROT) to expand access to vector manufacturing.

Research and development expense related to executed addenda under the master translational research service agreements with Penn recognized in the accompanying statements of operations was $3,250 and $3,786 for the years ended December 31, 2024 and 2023, respectively. The Company iscommitted to pay up to $3,000 under the CARTA Services Agreement for cell processing manufacturing through December 31, 2025. The Company may incur additional expenses up to$643 through the remaining term of the CAROT Amended Addendum.

Exclusive License Agreement with IASO Biotherapeutics

On October 7, 2022, the Company entered into an Exclusive License Agreement (the IASO Agreement) with Nanjing IASO Biotherapeutics Co., Ltd. (IASO). Pursuant to the IASO Agreement, the Company received an exclusive, worldwide license under certain IASO intellectual property to use a novel clinical-stage anti-CD19 binder to develop, manufacture, commercialize and otherwise exploit T cell products directed to CD19 for the purpose of diagnosis, prevention or treatment of any autoimmune or alloimmune indications in humans. As partial consideration for the exclusive license, IASO received an upfront payment of $2,500. IASO is also eligible to receive up to mid double digit millions in milestone payments based upon the achievement of specified pre-clinical, development and regulatory milestones, and up to an additional low triple digit millions in milestone payments based upon achievement of specified sales milestones, for a total consideration, inclusive of the upfront payment, of up to $162,000, along with tiered mid-single digit royalties on future net sales for licensed products that may result from the IASO Agreement. Upon the U.S. Food and Drug Association’s clearance of the rese-cel Investigational New Drug application for the treatment of systemic lupus erythematosus in March 2023, a milestone payment of $1,000 was recognized in the accompanying statements of operations. A milestone payment of $1,500 was paid to IASO in the first quarter of 2024 after the first patient in a rese-cel trial was dosed.

IASO has the right of first negotiation if the Company desires to grant a third party an exclusive license to develop, manufacture, commercialize or otherwise exploit the licensed products in the Greater China region. Pursuant to the IASO Agreement, each of IASO and the Company have agreed, subject to certain exceptions, to refrain from engaging in certain competitive activities with respect to certain programs. The Company also may sublicense through multiple tiers the rights granted to it by IASO under the IASO Agreement at any time, however, it must pay IASO a low double-digit percentage of any revenue obtained from sublicenses or options to third parties, subject to certain customary exclusions. The IASO Agreement will continue on a country-by-country, licensed product-by-licensed product basis until the expiration of the royalty term as identified in the IASO Agreement, unless earlier terminated. Each of the Company and IASO may terminate the Agreement for a material, uncured breach or insolvency of the other party. The Company may also terminate the Agreement at will upon advance written notice and in the event IASO rejects the Agreement due to bankruptcy-related matters. IASO may also terminate the Agreement if the Company fails to achieve certain specified diligence milestones in a timely manner and/or if the Company commences any patent challenges with respect to the patents and patent applications relating to the licensed sequence, in each case upon advance written notice.

Licence and Supply Agreement with Oxford Biomedica

In December 2021, the Company entered into a Licence and Supply agreement (LSA) with Oxford Biomedica (UK) Limited (Oxford), wherein the LSA grants the Company a non-exclusive license to Oxford’s LentiVector® platform for its application in the Company’s DSG3-CAART program and put in place a multi-year vector supply agreement. Under the terms of the agreement, the Company was required to pay Oxford an upfront fee, as well as costs associated with initial vector manufacturing activities for a total cost incurred of $1,100. Oxford is eligible to receive regulatory and sales milestones in the low tens of millions and royalties in the low single digits on net sales of products that incorporate the Oxford technology. In May 2023, the Company amended the LSA with Oxford to expand the license to include the Company's rese-cel program for an upfront fee of $500, and in August 2023, the Company and Oxford entered into a vector supply agreement for rese-cel, and a related second amendment to the LSA, with a total cost under the vector supply agreement of up to approximately $5,000, of which approximately $3,500 and $1,500 were recognized as research and development expense for the years ended December 31, 2024 and 2023, respectively. In February 2024, the Company and Oxford entered into a third amendment to the LSA to update the patent schedule. In June 2024, the Company and Oxford entered into a fourth amendment to the LSA elimin ating royalties on net sales of products that incorporate the Oxford technology if Oxford manufactures the vector. In December 2024, the Company and Oxford entered into a work order with a cost of approximately $9,000 for certain process characterization activities as part of commercial readiness activities. The Company can terminate the LSA or any work order under the LSA at will upon advance written notice and subject to certain cancellation fees.

Option and License Agreement with Autolus

In January 2023, the Company entered into an Option and License Agreement (Autolus Agreement) with Autolus Holdings (UK) Limited (Autolus), wherein the Autolus Agreement granted the Company a non-exclusive license to access Autolus' RQR8 technology in its CD19-CAR T cell therapy program, and subject to additional nominal option exercise fees, up to four additional targets. In January 2025, the Company and Autolus agreed to novate the Autolus Agreement with both Autolus and Autolus Limited jointly assuming the rights, obligations and liabilities of Autolus, under the Autolus Agreement. Under the terms of the Autolus Agreement, the Company was required to pay Autolus an upfront license fee of $1,200 that was recognized as expense in the first quarter of 2023 in the accompanying statements of operations, of which $1,100 was paid in 2023 and $100 was paid in January 2024. Autolus is also eligible to receive regulatory milestones of up to $12,000 for each licensed target, sales milestones of up to a total of $15,000 and royalties in the low single digits on net sales of all products that incorporate the RQR8 technology. The Autolus Agreement will continue on a country-by-country, licensed product-by-licensed product basis until the expiration of the royalty term as identified in the Autolus Agreement, unless earlier terminated. The Company can terminate the Autolus Agreement at will upon advance written notice. Each of the Company and Autolus may terminate the Agreement for a material, uncured breach or insolvency of the other party.

7. Commitments and Contingencies

Manufacturing Agreements

In January 2021, the Company entered into a Development and Manufacturing Services Agreement (WuXi Agreement) with WuXi Advanced Therapies, Inc. (WuXi) to serve as an additional cell processing manufacturing partner for the MuSK-CAART Phase 1 clinical trial, or MusCAARTes TM trial. The WuXi Agreement is scheduled to expire upon completion of WuXi's services related to MuSK-CAART and rese-cel. In August 2023, and as extended in August 2024, the Company entered into an agreement with WuXi to serve as one of the Company's manufacturing partners for the global clinical development of rese-cel in multiple indications, including potential late-stage clinical trials and commercial readiness activities for rese-cel. Under the August 2023 work orders, WuXi converted the Company’s non-dedicated suite to a dedicated suite for GMP manufacturing for the Company’s rese-cel and MuSK-CAART programs, or the Dedicated Suite, for an initial term of 18 months with two 18-month extensions at the Company’s sole option on six months' notice prior to the end of the term. In August 2024, the Company sent a notice to WuXi to extend the initial term of the WuXi Agreement by 18 months through August 2026. In addition, the Company agreed to certain monthly minimum runs. In August 2024, the 2023 work order related to GMP manufacturing was amended to reduce the minimum monthly runs through the end of 2024. In lieu of the original $1,500 termination fee under the terms of the WuXi Agreement, the Company would incur up to a $1,080 terminationfee if it terminates both the rese-cel and MuSK-CAART work orders for any reason. The Company may terminate for conveniencethe WuXi Agreement or any work order with six months' prior written notice. However, the Company may not terminate the Dedicated Suite without terminating both the MuSK-CAARTand rese-cel GMP run work orders. WuXi may terminate for convenience the WuXi Agreement or any work order on 18 months' prior written notice, but such notice may not be effective prior to February 2028.

In December 2024, the Company entered into a Development and Manufacturing Services Agreement (the Lonza Agreement) with Lonza Houston Inc. (Lonza) to serve as one of the Company's manufacturing partners for the global clinical development of rese-cel in multiple indications, including potential late-stage clinical trials and preparations for commercial readiness. Under the initial work order, Lonza will perform cell therapy manufacturing activities for Cabaletta’s CAR-T cell therapy product rese-cel for a term of 12 months and total cost of approximately $16,000 with the ability to extend the manufacturing period subject to the terms of the Lonza Agreement.

Other Purchase Commitments

In the normal course of business, the Company enters into various purchase commitments with third-party contract manufacturers for the manufacture and processing of its product candidates and related raw materials, contracts with contract research organizations for clinical trials and agreements with vendors for other services and products for operating purposes. These agreements generally provide for termination or cancellation, other than for costs already incurred.

Indemnification

The Company enters into certain types of contracts that contingently require the Company to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company’s Amended and Restated Bylaws, as amended, (bylaws) under which the Company must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers and consultants for liabilities arising out of their relationship, (iii) contracts under which the Company may be required to indemnify partners against certain claims, including claims from third parties asserting, among other things, infringement of their intellectual property rights, and (iv) procurement, consulting, or license agreements under which the Company may be required to indemnify vendors, consultants or licensors for certain claims, including claims that may be brought against them arising from the Company’s acts or omissions with respect to the supplied products, technology or services. From time to time, the Company may receive indemnification claims under these contracts in the normal course of business. In addition, under these contracts, the Company may have to modify the accused infringing intellectual property and/or refund amounts received.

In the event that one or more of these matters were to result in a claim against the Company, an adverse outcome, including a judgment or settlement, may have a material adverse effect on the Company’s future business, operating results or financial condition. It is not possible to determine the maximum potential amount under these contracts due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement.

Litigation

From time to time, the Company may become involved in litigation or legal proceedings. While the outcome of any such proceedings cannot be predicted with certainty, as of December 31, 2024, the Company is not involved in any material litigation or legal proceedings that it would expect to have a material adverse impact on its financial position, results of operations, or cash flows.

8. Segment Information

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the CODM in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is the CEO. The Company has determined that it has one operating and reportable segment. The segment consists of the development of clinical and preclinical product candidates for the discovery and development of innovative engineered T cell therapies and related administrative activities. The

CODM assesses performance and allocates resources based on the Company’s consolidated statement of operations, which is reported on the income statement as consolidated net loss and considers forecast-to-actuals variances on a quarterly basis for expenses that are deemed significant. Further, the CODM reviews the segment’s assets based on the consolidated balance sheet to assess liquidity and funding capacity. The majority of the Company's assets are located in the United States.

The Company’s CODM views specific categories within expenses as significant given the direct correlation between cash burn and profitability as a pre-revenue company. Significant segment expenses, as provided to the CODM, are presented below. For additional information on the year over year change of segment expenses refer to Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

(1)Other research and development costs includes costs associated with information technology, travel, medical and scientific symposiums and conferences.

9. Leases

The Company leases office and laboratory space in addition to a manufacturing agreement which has been determined to contain an embedded lease.

Operating lease commitments

The Company leases office and laboratory space which include rent escalations and are subject to additional variable charges, including common area maintenance, property taxes and property insurance. Given the variable nature of such costs, they are recognized as expense as incurred. Additionally, some of the Company’s leases are subject to certain fixed fees which the Company has determined to be non-lease components. The Company has elected the practical expedient to account for lease and non-lease components as a single-lease component and has included fixed payments related to non-lease components in calculating the operating lease liability. In 2024, the Company extended the terms of its lab and office operating leases and leased additional lab space resulting in an increase in the right-of-use asset and lease liability of $4,242.

Finance lease commitments - Embedded leases

As described further in Note 7, in August 2023, the Company entered into new work orders under the WuXi Agreement for WuXi to serve as one of the Company’s cell processing manufacturing partners for the global clinical development of rese-cel. WuXi converted the Company’s non-dedicated suite to a Dedicated Suite for GMP manufacturing for the Company’s rese-cel and MuSK-CAART programs, for an initial term of 18 months. Theterms of the August 2023 work orders included both fixed costs and contingent variable costs. The lease commenced October 1, 2023. In 2024, the Company remeasured the lease due to resolution of the contingency related to variable costs and an amendment to the 2023 work order to extend the term of the agreement for an additional 18 months through August

2026 resulting in an increase in the right-of-use asset and lease liability of $10,963. The Company may terminate the Dedicated Suite lease for convenience with six months’ prior written notice and up to a $1,080 termination fee if both the rese-cel and MuSK-CAART work orders are terminated.

As described further in Note 7, in December 2024, the Company entered into the Lonza Agreement with Lonza to serve as one of our manufacturing partners. Under the initial work order, Lonza will perform cell therapy manufacturing activities for our CAR-T cell therapy product rese-cel for a term of 12 months and total cost of approximately $16,000 with the ability to extend the manufacturing period subject to the terms of the Lonza Agreement. The Lonza Agreement is currently being evaluated for lease accounting under ASC 842. No right-of-use asset or liability was recognized as of December 31, 2024, as lease commencement begins in fiscal year 2025.

Summary of lease costs recognized under ASC 842

The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating and finance leases for the years ended December 31, 2024 and 2023.

For finance leases embedded in CDMO arrangements, interest expense is recognized using the effective interest method, applying the Company's incremental borrowing rate as required by ASC 842, and amortization expense is recognized on a straight-line basis over the shorter of the life of the asset or the term of the lease.

Future lease payments under the non-cancelable operating and finance leases as of December 31, 2024 are as follows:

10. Common Stock

Common Stock

Pursuant to the Company’s Third Amended and Restated Certificate of Incorporation filed in October 2019, the Company is authorized to issue 143,590,481 shares of voting common stock and 6,409,519 shares of non-voting common stock. Holders of voting common stock shall have the exclusive right to vote for the election of directors of the Company and on all other matters requiring stockholder action. Each share of the Company’s non-voting common stock may be converted at any time into one share of common stock at the option of its holder by providing 61 days written notice to the Company, subject to certain limitations, as described in the amended and restated certificate of incorporation. In May 2024,1,444,295 shares of non-voting common stock was converted to voting common stock and no shares of non-voting common stock remain outstanding.

May 2023 Financing

In May 2023, the Company issued 8,337,500 shares of its common stock in an underwritten public offering, including the exercise in full by the underwriters of their option to purchase an additional 1,087,500 shares, at a public offering price of $12.00 per share. Aggregate net proceeds were $93,755 after deducting underwriting discounts and commissions and offering expenses of $6,295.

December 2022 Financing

In December 2022, the Company issued 126,815 shares of its common stock at a price of $5.52 per share and to certain investors in lieu of common stock, pre-funded warrants to purchase 6,213,776 shares of common stock at a price of $5.51999 per pre-funded warrant. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $0.00001 per share exercise price of such pre-funded warrant. Aggregate net proceeds were $32,562 after deducting underwriting discounts and commissions and offering expenses. As of December 31, 2024,6,213,775 pre-funded warrants had been exercised andno warrants remain outstanding.

The pre-funded warrants were classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company’s common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return.

At-the-Market Offering

On March 21, 2024, the Company filed an automatic shelf registration statement (S-3ASR) in relation to the registration of common stock, preferred stock, debt securities, warrants and/or units of any combination thereof for the purposes of selling, from time to time, the Company’s common stock, debt securities or other equity securities in one or more offerings. This S-3ASR became effective immediately. We intend to convert the S-3ASR to S-3 by post-effective amendments in connection with the filing of this Annual Report.

The Company has a Sales Agreement with Cowen and Company, LLC (Cowen) to provide for the offering, issuance and sale of up to an aggregate amount of $200.0 million of common stock from time to time in “at-the-market” offerings (2024 ATM Program) pursuant to its S-3ASR, and subject to the limitations thereof. In December 2024, the Company sold 1,225,000 shares pursuant to the 2024 ATM Program for net proceeds of $5,129, after deducting commissions of $105.

The Company previously had a Sales Agreement with Cowen to provide for the offering, issuance and sale of up to an aggregate amount of $100.0 million of common stock from time to time in “at-the-market” offerings (2023 ATM Program) pursuant to its shelf registration statement on Form S-3 (File No. 333-270599), which was declared effective April 26, 2023. During the year ended December 31, 2023, the Company sold 4,760,899 shares pursuant to the 2023 ATM Program for net proceeds of $91,740, after deducting commissions of $2,352. In the first quarter of 2024, the Company sold 258,070 additional shares, completing the 2023 ATM Program for net proceeds of $5,746, after deducting commissions of $147.

2018 Stock Option and Grant Plan

In September 2018, the Company adopted the 2018 stock option and grant plan (the 2018 Plan), which provided for the Company to sell or issue common stock, or other stock-based awards, to employees, members of the board of directors and consultants of the Company. The Company generally granted stock-based awards with service conditions only (service-based awards), although there was one grant with performance conditions. As of December 31, 2020, there areno unvested options with performance conditions. Stock options granted under the 2018 Plan generally vest over three tofour years. There were 1,959,411 options granted under the 2018 Plan prior to the Company’s IPO in October 2019. No further grants may be made under the 2018 Plan subsequent to the IPO.

2019 Stock Option and Incentive Plan

The 2019 Stock Option and Incentive Plan (2019 Plan) was approved by the Company’s board of directors on October 14, 2019, and became effective on October 23, 2019. The 2019 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, directors and consultants. The number of shares initially reserved for issuance under the 2019 Plan was 2,342,288, which will be increased each January 1 thereafter by 4% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s board of directors or compensation committee of the board of directors. On June 1, 2023, at the 2023 Annual Meeting of Stockholders of the Company, the stockholders of the Company approved Amendment No. 1 to the 2019 Plan, increasing the number of shares of common stock reserved for issuance under the 2019 Plan by 3,000,000 shares. On January 1, 2025, the total number of shares under the 2019 Plan was increased by 2,029,724 shares pursuant to the 2019 Plan Evergreen Provision. As of December 31, 2024, there were 1,379,305 shares remaining available for issuance under the 2019 Plan.

A summary of the stock option activity is presented below:

The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock. The weighted average grant-date fair value of stock options granted during the year ended December 31, 2024 and 2023 was $13.44 and $9.51, respectively.

The fair value of each award is estimated using Black-Scholes based on the following assumptions:

Black-Scholes requires the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Expected term—The expected term represents the period that stock-based awards are expected to be outstanding. The expected term for option grants is determined using the simplified method, which is the midpoint between the vesting period and the contractual term of the option.

Expected volatility—As a privately held company prior to the Company’s IPO in October 2019, the Company has limited trading history for its common stock and, as such, the expected volatility is estimated based on a weighted average volatility for the Company's stock price and comparable publicly traded biotechnology companies over a period equal to the expected term of the stock-based awards. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-free interest rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of a stock-based award.

Expected dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Stock-based Compensation

The Company has recorded stock-based compensation in the accompanying statements of operations as follows:

As of December 31, 2024, there was $51,239 of unrecognized compensation cost related to unvested option awards, which is expected to be recognized over a weighted-average period of 2.8 years.

2019 Employee Stock Purchase Plan

The 2019 Employee Stock Purchase Plan (2019 ESPP) was approved by the Company’s board of directors on October 14, 2019, and became effective on October 23, 2019. A total of 234,229 shares of common stock were initially reserved for issuance under the 2019 ESPP, and such number of shares will be increased each January 1 thereafter through January 1, 2029 by the least of (i)234,229 shares of common stock, (ii)1% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or (iii) such lesser number of shares determined by the 2019 ESPP’s administrator. There wasno increase to the total number of shares available under the 2019 ESPP on January 1, 2024, 2023 or 2022, respectively. As of December 31, 2024, there were 314,259 shares remaining available for issuance under the 2019 ESPP.

Employee contributions are made through payroll deductions of up to 15% of eligible compensation over the offering period. A participant may not accrue rights to purchase more than $25 worth of the Company’s common stock for each calendar year in which such right is outstanding. At the end of each offering period, shares of the Company’s common stock may be purchased at 85% of the lesser of the Company’s common stock on (i) the first trading day of the relevant offering period and (ii) the last trading day of the relevant offering period. Each offering period will be six months in duration and will commence on each December 1 and June 1.

11. Income Taxes

The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows:

Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s deferred tax assets and liabilities consisted of the following:

The Company increased its valuation allowance by $38,163 for the year ended December 31, 2024 in order to maintain a full valuation allowance against its deferred tax assets. Based on the Company’s history of losses, the Company recorded a full valuation allowance against its deferred tax assets as of December 31, 2024. The Company intends to maintain a valuation allowance until sufficient positive evidence exists to support a reversal of the allowance.

As of December 31, 2024, the Company had federal, state and local net operating loss carryforwards of $157,448, $181,362 and $88,701, respectively; $157,198 of the federal net operating losses do not expire, and the remaining $250 expire in 2037. The state net operating losses begin to expire in 2037. The local net operating losses begin to expire in 2042. As of December 31, 2024, the Company had federal and state research and development tax credit carryforwards of $15,684 and $612, respectively, which begin to expire in 2038 and 2036, respectively. Under the provisions of Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the IRC), these net operating losses, credit carryforwards and other tax attributes may be subject to limitation based on previous significant changes in ownership and upon future significant changes in ownership of the Company, as defined by the IRC.

The Company files income tax returns in the U.S. federal jurisdiction as well as in Pennsylvania and Philadelphia. The tax years 2023, 2022 and 2021 remain open to examination by the jurisdictions where the Company is subject to tax.

The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. As of December 31, 2024, the Company hadno unrecognized income tax benefits that would affect the Company’s effective tax rate if recognized.

12. Net Loss Per Share

The Company calculates basic and diluted net loss per share in conformity with the two-class method required for participating securities. For the year ended December 31, 2023, the Company had voting and non-voting common stock outstanding. In May 2024,1,444,295 shares of non-voting common stock was converted to voting common stock and as of December 31, 2024, no shares of non-voting common stock remain outstanding. Since the rights of the voting and non-voting common stock are identical, except with respect to voting, the undistributed losses of the Company have been allocated on a proportionate basis to the two classes. Basic net loss per share of common stock is computed by dividing the net loss per share of common stock by the weighted average number of shares of common stock outstanding for the period.

The weighted average shares of common stock outstanding as of December 31, 2023 included outstanding pre-funded warrants to purchase up to an aggregate of 1,168,054 shares of common stock. No pre-funded warrants remain outstanding as of December 31, 2024.

Diluted net loss per share is calculated using the if-converted method, which assumes conversion of all non-voting common stock to voting common stock.

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive:

13. 401(k) Savings Plan

The Company maintains a defined-contribution savings plan under Section 401(k) of the IRC, or the 401(k) Plan. The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis. Effective January 1, 2020, the Plan provided for matching contributions on a portion of participant contributions pursuant to the 401(k) Savings Plan’s matching formula, up to 4% of eligible compensation. All matching contributions and participant contributions vest immediately. Contributions totaled $894 and $521 for the years ended December 31, 2024 and 2023, respectively, and have been recorded in the statements of operations.

EXHIBIT INDEX