1. Organization

Description of the business

CARGO Therapeutics, Inc. (the “Company”) was incorporated in the state of Delaware in December 2019 as Syncopation Life Sciences, Inc. and changed its name to CARGO Therapeutics, Inc. in September 2022. The Company is a biotechnology company historically focused on designing, engineering and developing next generation, potentially curative cell therapies for cancer patients.

Restructuring

On January 28, 2025, the Company’s board of directors (the “Board”) approved a reduction in the Company’s workforce by approximately 50% in connection with the Company’s election to discontinue the Phase 2 study of firicabtagene autoleucel (firi-cel). The Company had no plans for restructuring as of December 31, 2024. Therefore, no restructuring expense or related liability was recorded as of December 31, 2024.

On March 18, 2025, in connection with the Company’s ongoing strategic assessment and evaluation of strategic options, the Company announced that the Board determined to suspend various development efforts and continue to pursue potential strategic alternatives such as a reverse merger, other business combination, dissolution and wind-down, or cash sale transaction. On March 13, 2025, the Board also approved a reduction in the Company’s current workforce of approximately 90% (collectively with the January 28, 2025 reduction in force, the “2025 Restructuring”).

In connection with the 2025 Restructuring, the Company recorded a restructuring charge of $37.1 million and $83.4 million during the three and six months ended June 30, 2025, respectively. The restructuring charge includes: (i) severance and termination benefit expense for employees terminated with separation dates between April 2025 and November 2025, (ii) a charge related to the impairment of property and equipment, including research and development equipment, leasehold improvements, furniture and fixtures, computer equipment and software, and (iii) contract termination and other costs. Refer to Note 10 for additional information on the 2025 Restructuring.

Since its founding through the 2025 Restructuring, the Company has devoted substantially all of its resources to organizing and staffing the Company, business planning, raising capital, establishing licensing arrangements, building its proprietary platform technologies, discovering its product candidates, establishing its intellectual property portfolio, conducting research, preclinical studies, and clinical trials, establishing arrangements with third parties for the manufacture of its product candidates and related raw materials, and providing general and administrative support for these operations.

The Agreement and Plan of Merger

On July 7, 2025, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Concentra Biosciences, LLC, a Delaware limited liability company (“Concentra”), and Concentra Merger Sub III, Inc., a Delaware corporation and a wholly owned subsidiary of Concentra (“Merger Sub”). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock by Concentra through a cash tender offer (the “Offer”) by Merger Sub, for a price per share of the common stock of (A) $4.379 in cash (the “Cash Amount”), subject to applicable tax withholding and without interest; plus (B) one contingent value right (“CVR”, and collectively with the Cash Amount, the “Offer Price”) and (ii) the merger of Merger Sub with and into the Company (the “Merger”) with the Company surviving the Merger.

Refer to Note 12—Subsequent Events for additional details.

Liquidity

Since inception, the Company has incurred significant operating losses and negative cash flows, and it expects that it will continue to incur costs and expenditures in connection with its streamlined operations. As of and for the

six months ended June 30, 2025, the Company had an accumulated deficit of $447.1 million, cash and cash equivalents and marketable securities of $252.6 million and negative cash flows from operations of $115.1 million. The Company believes its existing cash and cash equivalents and marketable securities will be sufficient to support operations for at least 12 months from the issuance of these unaudited condensed financial statements.