Description of the Business	3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business Cartesian Therapeutics, Inc., or the Company, was incorporated in Delaware on December 10, 2007, and is headquartered in Frederick, Maryland. The Company is a late clinical-stage biotechnology company pioneering cell therapy for the treatment of autoimmune diseases. The Company leverages its proprietary technology and manufacturing platform to introduce mRNA into cells to provide a therapeutic effect to patients suffering from a variety of autoimmune conditions. Unlike DNA, mRNA degrades naturally over time without integrating into the cell’s genetic material. The Company’s cell therapies are designed to be dosed repeatedly like conventional drugs, administered in an outpatient setting and given without pre-treatment chemotherapy, which is required with many conventional cell therapies. The Company’s Product Candidates The Company aims to provide a personalized approach to treating patients that begins with the collection of a patient’s cells, which are then used to manufacture the Company’s cell therapy product candidates. Once a patient’s cells have expanded in the Company’s process, mRNA is introduced to deliver a chimeric antigen receptor into the cell. Once the manufacturing process is complete, the product candidate is sent back to the treating physician where they administer six weekly infusions of the Company’s cell therapy candidate to the patient. The Company’s product candidates are specifically designed to target and destroy the pathogenic, self-reactive cells that are the underlying cause of the autoimmune disease, with the goal of creating a precision immune reset for the patient. Descartes-08, the Company’s lead cell therapy product candidate, is an autologous chimeric antigen receptor T-cell therapy, or CAR-T, product targeting B-cell maturation antigen, or BCMA, in clinical development for the treatment of generalized myasthenia gravis, or MG, and myositis, specifically, moderate to severe multi-refractory dermatomyositis and antisynthetase syndrome. In contrast to conventional DNA-based CAR T-cell therapies, the Company’s CAR-T administration is designed to not require preconditioning chemotherapy, to be administered in the outpatient setting and does not carry the risk of genomic integration associated with cancerous transformation. Descartes-08 has been granted Orphan Drug Designation and Regenerative Medicine Advanced Therapy Designation by the U.S. Food and Drug Administration, or FDA, for the treatment of MG, and Rare Pediatric Disease Designation for the treatment of juvenile dermatomyositis. Liquidity and Management’s Plan As of March 31, 2026, the Company had an accumulated deficit of $861.6 million. The Company anticipates operating losses to continue for the foreseeable future due to, among other things, costs related to research and development of its product candidates and its administrative organization. The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain and sustain profitable operations. The successful development of product candidates requires substantial working capital, which may not be available to the Company on favorable terms or at all. As of March 31, 2026, the Company’s cash, cash equivalents, and restricted cash were $120.4 million, of which $1.7 million was restricted cash related to lease commitments. The Company believes the cash, cash equivalents and restricted cash as of March 31, 2026 will enable it to fund its current planned operations for at least the next 12 months. Further, the liability associated with the CVR Agreement (as defined below) will be settled solely through cash flow received under the Company’s License and Development Agreement, or as so amended, the Sobi License, with Swedish Orphan Biovitrum AB (publ.), or Sobi, and any other Gross Proceeds (as defined in the CVR Agreement) net of certain agreed deductions. Under the CVR Agreement, 100% of all milestone payments, royalties and other amounts paid to the Company or controlled entities under the Sobi License, and any other Gross Proceeds will be distributed, net of specified deductions, to holders of the CVRs. There is no obligation to the Company to fund any amount related to the CVR liability. See Note 5, “Fair Value Measurements”. If the Company is unable to obtain additional funding on a timely basis, it may be forced to significantly curtail, delay, or discontinue one or more of its planned research or development programs or be unable to expand its operations or otherwise capitalize on its commercialization of its product candidates.

Cartesian Therapeutics, Inc., or the Company, was incorporated in Delaware on December 10, 2007, and is headquartered in Frederick, Maryland. The Company is a late clinical-stage biotechnology company pioneering cell therapy for the treatment of autoimmune diseases. The Company leverages its proprietary technology and manufacturing platform to introduce mRNA into cells to provide a therapeutic effect to patients suffering from a variety of autoimmune conditions. Unlike DNA, mRNA degrades naturally over time without integrating into the cell’s genetic material. The Company’s cell therapies are designed to be dosed repeatedly like conventional drugs, administered in an outpatient setting and given without pre-treatment chemotherapy, which is required with many conventional cell therapies.

The Company aims to provide a personalized approach to treating patients that begins with the collection of a patient’s cells, which are then used to manufacture the Company’s cell therapy product candidates. Once a patient’s cells have expanded in the Company’s process, mRNA is introduced to deliver a chimeric antigen receptor into the cell. Once the manufacturing process is complete, the product candidate is sent back to the treating physician where they administer six weekly infusions of the Company’s cell therapy candidate to the patient. The Company’s product candidates are specifically designed to target and destroy the pathogenic, self-reactive cells that are the underlying cause of the autoimmune disease, with the goal of creating a precision immune reset for the patient.

Descartes-08, the Company’s lead cell therapy product candidate, is an autologous chimeric antigen receptor T-cell therapy, or CAR-T, product targeting B-cell maturation antigen, or BCMA, in clinical development for the treatment of generalized myasthenia gravis, or MG, and myositis, specifically, moderate to severe multi-refractory dermatomyositis and antisynthetase syndrome. In contrast to conventional DNA-based CAR T-cell therapies, the Company’s CAR-T administration is designed to not require preconditioning chemotherapy, to be administered in the outpatient setting and does not carry the risk of genomic integration associated with cancerous transformation. Descartes-08 has been granted Orphan Drug Designation and Regenerative Medicine Advanced Therapy Designation by the U.S. Food and Drug Administration, or FDA, for the treatment of MG, and Rare Pediatric Disease Designation for the treatment of juvenile dermatomyositis.

As of March 31, 2026, the Company had an accumulated deficit of $861.6 million. The Company anticipates operating losses to continue for the foreseeable future due to, among other things, costs related to research and development of its product candidates and its administrative organization. The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain and sustain profitable operations. The successful development of product candidates requires substantial working capital, which may not be available to the Company on favorable terms or at all.

As of March 31, 2026, the Company’s cash, cash equivalents, and restricted cash were $120.4 million, of which $1.7 million was restricted cash related to lease commitments. The Company believes the cash, cash equivalents and restricted cash as of March 31, 2026 will enable it to fund its current planned operations for at least the next 12 months.

Further, the liability associated with the CVR Agreement (as defined below) will be settled solely through cash flow received under the Company’s License and Development Agreement, or as so amended, the Sobi License, with Swedish Orphan Biovitrum AB (publ.), or Sobi, and any other Gross Proceeds (as defined in the CVR Agreement) net of certain agreed deductions. Under the CVR Agreement, 100% of all milestone payments, royalties and other amounts paid to the Company or controlled entities under the Sobi License, and any other Gross Proceeds will be distributed, net of specified deductions, to holders of the CVRs. There is no obligation to the Company to fund any amount related to the CVR liability. See Note 5, “Fair Value Measurements”.