0001453687-26-000082 | 10-Q | XBRL Viewer | Cartesian Therapeutics INC

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Leases - Schedule of Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Leases [Abstract]
Operating lease cost	$ 583	$ 584
Variable lease cost	431	406
Short-term lease cost	4	11
Total lease cost	$ 1,018	$ 1,001

Goodwill and Indefinite-Lived Intangible Assets	3 Months Ended
Goodwill and Indefinite-Lived Intangible Assets	Mar. 31, 2026
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Indefinite-Lived Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets As of March 31, 2026, the Company has goodwill of approximately $48.2 million and an indefinite-lived intangible asset of $93.9 million related to Descartes-08 for MG. There were no changes to the carrying value of the Company’s goodwill or in-process research and development asset related to Descartes-08 for MG during the three months ended March 31, 2026 and 2025.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2026
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of presentation and consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Selecta (RUS), LLC, or Selecta (RUS), a Russian limited liability corporation, and Cartesian Bio, LLC, a Delaware limited liability company, which is a variable interest entity for which the Company is the primary beneficiary and have been prepared in conformity with accounting principles generally accepted in the United States of America, or U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the relevant Accounting Standards Codification, or ASC and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. All significant intercompany accounts and transactions have been eliminated. The accompanying unaudited consolidated financial statements for the three months ended March 31, 2026 and 2025 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2025 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 9, 2026. The unaudited interim financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of management, the accompanying unaudited interim consolidated financial statements contain all adjustments that are necessary for a fair statement of the Company’s financial position as of March 31, 2026, the consolidated results of operations for the three months ended March 31, 2026, and cash flows for the three months ended March 31, 2026. Such adjustments are of a normal and recurring nature. The results of operations for the three months ended March 31, 2026 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2026. Significant accounting policies The Company disclosed its significant accounting policies in Note 2, “Summary of Significant Accounting Policies” included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. There have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2026. Recent Accounting Pronouncements Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Income Statement Reporting- Comprehensive Income- Expense Disaggregation Disclosures (ASU 2024-03), which requires public companies to disclose, in interim and annual reporting periods, additional information about certain expenses in notes to financial statements, including purchases of inventory, employee compensation, depreciation, amortization of intangible assets, and selling expenses. This guidance will be effective for the annual period beginning the year ended December 31, 2027 and for interim periods beginning January 1, 2028, with early adoption permitted. The Company is currently evaluating the impact of the standard’s adoption on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-10, Government Grants (Topic 832): Accounting for Government Grants Received by Business Entities (ASU 2025-10), which establishes authoritative guidance on the recognition, measurement, presentation, and disclosure of government grants. Under ASU 2025-10, government grants are recognized when it is probable that the entity will both comply with the conditions of the grant and the grant will be received. The ASU provides specific accounting models for grants related to assets and grants related to income, including options to recognize government grants as deferred income or as a reduction of the asset’s cost basis. The ASU also requires enhanced disclosures regarding the nature of government grants, significant terms and conditions, accounting policies applied, and amounts recognized in the financial statements. ASU 2025-10 is effective for fiscal years beginning after December 15, 2028, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2025-10 on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements (ASU 2025-11), which clarifies the guidance in Topic 270 to improve the consistency of interim financial reporting. The ASU provides a comprehensive list of required interim disclosures and introduces a disclosure principle requiring entities to disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for fiscal years beginning after December 15, 2027, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2025-11 on its consolidated financial statements and related disclosures.
Goodwill and Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets As of March 31, 2026, the Company has goodwill of approximately $48.2 million and an indefinite-lived intangible asset of $93.9 million related to Descartes-08 for MG. There were no changes to the carrying value of the Company’s goodwill or in-process research and development asset related to Descartes-08 for MG during the three months ended March 31, 2026 and 2025.

Segment Reporting - Narrative (Details)	3 Months Ended
Segment Reporting - Narrative (Details)	Mar. 31, 2026 segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments not disclosed flag	segment

Leases - Schedule of Maturity of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2026 USD ($)
Leases [Abstract]
2026 (remainder)	$ 3,571
2027	4,554
2028	2,529
2029	1,630
2030	1,679
Thereafter	852
Total future minimum lease payments	14,815
Less: Imputed interest	(2,960)
Total operating lease liabilities	$ 11,855

Leases

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Leases

The Company maintains operating leases for manufacturing, laboratory and office space located in Maryland and Massachusetts. In Frederick, Maryland, the Company occupies over 35,000 total square feet of integrated space under a lease agreement, or the Frederick Lease Agreement, and subsequent amendments entered into between February 2024 and June 2025, or the Amended Frederick Lease Agreement. The Amended Fredrick Lease Agreement is set to expire in 2031, carries an aggregate annual base rent of approximately $1.4 million and is subject to annual increases in accordance with the terms of the

Amended Frederick Lease Agreement. See Note 9, “Leases” to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 for further discussion of the Company’s leases.

For the three months ended March 31, 2026 and 2025, the components of lease costs were as follows (in thousands):


	Three Months Ended March 31,
	2026		2025
Operating lease cost	$	583	$	584
Variable lease cost	431		406
Short-term lease cost	4		11

Total lease cost	$	1,018	$	1,001

The maturity of the Company’s operating lease liabilities as of March 31, 2026 were as follows (in thousands):


	March 31, 2026
2026 (remainder)	$	3,571
2027	4,554
2028	2,529
2029	1,630
2030	1,679
Thereafter	852
Total future minimum lease payments	14,815
Less: Imputed interest	(2,960)
Total operating lease liabilities	$	11,855

Other information related to operating leases was as follows:


	March 31,
	2026			2025
Cash paid for amounts included in the measurement of lease liabilities (in thousands)	$	1,169		$	317
Weighted-average remaining lease term	3.7 years			4.4 years
Weighted-average discount rate	12.2		%	11.8		%

The changes in the Company’s right-of-use assets and lease liabilities for the three months ended March 31, 2026 and 2025 are reflected in the non-cash lease expense and accrued expenses and other liabilities, respectively, in the consolidated statements of cash flows.

Net Loss Per Share Allocable to Common Stockholders (Tables)

3 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share Allocable to Common Stockholders

The following table sets forth the computation of basic and diluted net loss per share allocable to common stockholders for the three months ended March 31, 2026 and 2025 (in thousands, except share and per-share data):


	Three Months Ended March 31,
	2026		2025
Numerator:
Net loss	$	(39,182)	$	(17,710)



Denominator:
Weighted-average common shares outstanding - basic and diluted	26,855,158		25,902,650



Net loss per share allocable to common stockholders:
Basic and diluted	$	(1.46)	$	(0.68)

Schedule of Potential Dilutive Shares of Common Stock Excluded from the Computation of the Diluted Net Loss Per Share Allocable to Common Stockholders

The following table represents the potential dilutive shares of common stock excluded from the computation of the diluted net loss per share allocable to common stockholders for all periods presented, as the effect would have been anti-dilutive:


	Three Months Ended March 31,
	2026	2025
Common stock options and restricted stock units	4,278,679	3,047,628
Warrants to purchase common stock	692,272	692,523
Series A Preferred Stock	4,026,346	4,026,346

Series B Preferred Stock	437,927	437,927
Total	9,435,224	8,204,424

Equity (Tables)

3 Months Ended

Mar. 31, 2026

Equity [Abstract]

Schedule of Warrant Activity

The following is a summary of the Company’s warrants as of March 31, 2026:


	Number of Warrants
	Equity classified	Liability classified	Total	Weighted-average exercise price




Outstanding at March 31, 2026	6,560	685,712	692,272	$	46.76

Schedule of Authorized Shares of Common Stock for Future Issuance

The Company has authorized shares of common stock for future issuance as of March 31, 2026 as follows:


			March 31, 2026
Exercise of warrants			692,272
Shares available for future stock incentive awards			3,641,284

Unvested restricted stock units			736,272
Outstanding common stock options			3,542,407
Series A Preferred Stock			4,026,346
Series B Preferred Stock			437,927

Total			13,076,508

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 16,985	$ 16,918
Less: Accumulated depreciation	(5,348)	(4,733)
Property and equipment, net	11,637	12,185
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	9,323	8,419
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	417	417
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	6,709	4,177
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	307	269
Office equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	170	170
Construction in process
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 59	$ 3,466

Net Loss Per Share Allocable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Loss Per Share Allocable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Numerator:
Net loss	$ (39,182)	$ (17,710)
Denominator:
Weighted-average common shares outstanding - basic (in shares)	26,855,158	25,902,650
Weighted-average common shares outstanding - diluted (in shares)	26,855,158	25,902,650
Net loss per share allocable to common stockholders:
Basic (in dollars per share)	$ (1.46)	$ (0.68)
Diluted (in dollars per share)	$ (1.46)	$ (0.68)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Fair Value Measurements - Schedule of Fair Value Measurement Inputs and Valuation Techniques for Warrants Liability (Details) - Valuation technique, option pricing model	Mar. 31, 2026	Dec. 31, 2025
Risk-free interest rate \| 2022 Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0.0368	0.0348
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0
Dividend yield \| 2022 Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0	0
Expected life (in years) \| 2022 Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, term	1 year 10 days	1 year 3 months 10 days
Expected volatility \| 2022 Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0.8914	0.8736

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Assets:
Total assets	$ 117,674	$ 122,724
Liabilities:
Warrant liability	47	141
Contingent value right liability	405,900	392,100
Total liabilities	405,947	392,241
Money market funds (included in cash equivalents)
Assets:
Money market funds (included in cash equivalents)	117,674	122,724
Level 1
Assets:
Total assets	117,674	122,724
Liabilities:
Warrant liability	0	0
Contingent value right liability	0	0
Total liabilities	0	0
Level 1 \| Money market funds (included in cash equivalents)
Assets:
Money market funds (included in cash equivalents)	117,674	122,724
Level 2
Assets:
Total assets	0	0
Liabilities:
Warrant liability	0	0
Contingent value right liability	0	0
Total liabilities	0	0
Level 2 \| Money market funds (included in cash equivalents)
Assets:
Money market funds (included in cash equivalents)	0	0
Level 3
Assets:
Total assets	0	0
Liabilities:
Warrant liability	47	141
Contingent value right liability	405,900	392,100
Total liabilities	405,947	392,241
Level 3 \| Money market funds (included in cash equivalents)
Assets:
Money market funds (included in cash equivalents)	$ 0	$ 0

Net Loss Per Share Allocable to Common Stockholders - Schedule of Potential Dilutive Shares of Common Stock Excluded from the Computation of the Diluted Net Loss Per Share Allocable to Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Potential common shares
Total (in shares)	9,435,224	8,204,424
Common stock options and restricted stock units
Potential common shares
Total (in shares)	4,278,679	3,047,628
Warrants to purchase common stock
Potential common shares
Total (in shares)	692,272	692,523
Preferred stock \| Series A Preferred Stock
Potential common shares
Total (in shares)	4,026,346	4,026,346
Preferred stock \| Series B Preferred Stock
Potential common shares
Total (in shares)	437,927	437,927

Net Loss Per Share Allocable to Common Stockholders

3 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Net Loss Per Share Allocable to Common Stockholders


	Three Months Ended March 31,
	2026		2025
Numerator:
Net loss	$	(39,182)	$	(17,710)



Denominator:
Weighted-average common shares outstanding - basic and diluted	26,855,158		25,902,650



Net loss per share allocable to common stockholders:
Basic and diluted	$	(1.46)	$	(0.68)


	Three Months Ended March 31,
	2026	2025
Common stock options and restricted stock units	4,278,679	3,047,628
Warrants to purchase common stock	692,272	692,523
Series A Preferred Stock	4,026,346	4,026,346

Series B Preferred Stock	437,927	437,927
Total	9,435,224	8,204,424

Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

The following table presents selected financial information with respect to the Company’s single operating segment for the three months ended March 31, 2026 and 2025 (in thousands):


	Three Months Ended March 31,
	2026		2025
Revenue:
Collaboration and license revenue	$	—	$	400
Grant revenue	78		700
Total revenue	78		1,100
Less:
Operating expenses:

Descartes-08 for MG	12,135		7,036
Descartes-08 for dermatomyositis	227		—
Early stage programs	355		990
Research and development employee expenses	3,828		3,702
Research and development stock-based compensation expense	949		1,275
Research and development facilities and other expenses	1,969		1,671
General and administrative	7,114		8,315

Other expense (income), net (1)	12,683		(4,179)
Net loss	$	(39,182)	$	(17,710)


(1) Includes interest income; gain on change in fair value of warrant liabilities; (loss) gain on change in fair value of contingent value right liability; and other expense, net.

Fair Value Measurements - Schedule of Roll-Forward of Fair Value for the Company’s Level 3 Warrant Liabilities and CVR Liability (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($)
Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 141
Change in fair value	(94)
Ending balance	47
CVR Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	392,100
Change in fair value	13,800
Ending balance	$ 405,900

Leases - Narrative (Details) - Frederick Lease Agreement $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($) ft²
Operating Leased Assets [Line Items]
Area of office space leased \| ft²	35,000
Aggregate annual base rent \| $	$ 1.4

Leases (Tables)

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Schedule of Components of Lease Costs and Other Information Related to Operating Leases

For the three months ended March 31, 2026 and 2025, the components of lease costs were as follows (in thousands):


	Three Months Ended March 31,
	2026		2025
Operating lease cost	$	583	$	584
Variable lease cost	431		406
Short-term lease cost	4		11

Total lease cost	$	1,018	$	1,001

Other information related to operating leases was as follows:


	March 31,
	2026			2025
Cash paid for amounts included in the measurement of lease liabilities (in thousands)	$	1,169		$	317
Weighted-average remaining lease term	3.7 years			4.4 years
Weighted-average discount rate	12.2		%	11.8		%

Schedule of Maturity of Operating Lease Liabilities

The maturity of the Company’s operating lease liabilities as of March 31, 2026 were as follows (in thousands):


	March 31, 2026
2026 (remainder)	$	3,571
2027	4,554
2028	2,529
2029	1,630
2030	1,679
Thereafter	852
Total future minimum lease payments	14,815
Less: Imputed interest	(2,960)
Total operating lease liabilities	$	11,855

Collaboration and License Agreements - Shenyang Sunshine Pharmaceutical Co., Ltd - Narrative (Details) - 3SBio License $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate amount of upfront and milestone-based payments	$ 7.0
Aggregate amount for future payments upon achievement of clinical and regulatory approval milestones for products containing ImmTOR platform	$ 15.0

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2026
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of presentation and consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Selecta (RUS), LLC, or Selecta (RUS), a Russian limited liability corporation, and Cartesian Bio, LLC, a Delaware limited liability company, which is a variable interest entity for which the Company is the primary beneficiary and have been prepared in conformity with accounting principles generally accepted in the United States of America, or U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the relevant Accounting Standards Codification, or ASC and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. All significant intercompany accounts and transactions have been eliminated. The accompanying unaudited consolidated financial statements for the three months ended March 31, 2026 and 2025 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2025 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 9, 2026. The unaudited interim financial statements have been prepared on the same basis as the audited consolidated financial statements. In the opinion of management, the accompanying unaudited interim consolidated financial statements contain all adjustments that are necessary for a fair statement of the Company’s financial position as of March 31, 2026, the consolidated results of operations for the three months ended March 31, 2026, and cash flows for the three months ended March 31, 2026. Such adjustments are of a normal and recurring nature. The results of operations for the three months ended March 31, 2026 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2026.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Income Statement Reporting- Comprehensive Income- Expense Disaggregation Disclosures (ASU 2024-03), which requires public companies to disclose, in interim and annual reporting periods, additional information about certain expenses in notes to financial statements, including purchases of inventory, employee compensation, depreciation, amortization of intangible assets, and selling expenses. This guidance will be effective for the annual period beginning the year ended December 31, 2027 and for interim periods beginning January 1, 2028, with early adoption permitted. The Company is currently evaluating the impact of the standard’s adoption on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-10, Government Grants (Topic 832): Accounting for Government Grants Received by Business Entities (ASU 2025-10), which establishes authoritative guidance on the recognition, measurement, presentation, and disclosure of government grants. Under ASU 2025-10, government grants are recognized when it is probable that the entity will both comply with the conditions of the grant and the grant will be received. The ASU provides specific accounting models for grants related to assets and grants related to income, including options to recognize government grants as deferred income or as a reduction of the asset’s cost basis. The ASU also requires enhanced disclosures regarding the nature of government grants, significant terms and conditions, accounting policies applied, and amounts recognized in the financial statements. ASU 2025-10 is effective for fiscal years beginning after December 15, 2028, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2025-10 on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements (ASU 2025-11), which clarifies the guidance in Topic 270 to improve the consistency of interim financial reporting. The ASU provides a comprehensive list of required interim disclosures and introduces a disclosure principle requiring entities to disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for fiscal years beginning after December 15, 2027, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2025-11 on its consolidated financial statements and related disclosures.

Fair Value Measurements - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Cash and cash equivalents	$ 118,641	$ 125,139	$ 180,434
Long-term restricted cash	1,735	1,735	1,669
Total cash, cash equivalents, and restricted cash	$ 120,376	$ 126,874	$ 182,103	$ 214,279

Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Revenue:
Collaboration and license revenue	$ 0	$ 400
Grant revenue	78	700
Total revenues	78	1,100
Operating expenses:
Research and development	19,463	14,674
General and administrative	7,114	8,315
Net loss	(39,182)	(17,710)
Operating Segment
Revenue:
Collaboration and license revenue	0	400
Grant revenue	78	700
Total revenues	78	1,100
Operating expenses:
General and administrative	7,114	8,315
Other expense (income), net	12,683	(4,179)
Net loss	(39,182)	(17,710)
Operating Segment \| Descartes-08 for MG
Operating expenses:
Research and development	12,135	7,036
Operating Segment \| Descartes-08 for dermatomyositis
Operating expenses:
Research and development	227	0
Operating Segment \| Early stage programs
Operating expenses:
Research and development	355	990
Operating Segment \| Research and development employee expenses
Operating expenses:
Research and development	3,828	3,702
Operating Segment \| Research and development stock-based compensation expense
Operating expenses:
Research and development	949	1,275
Operating Segment \| Research and development facilities and other expenses
Operating expenses:
Research and development	$ 1,969	$ 1,671

Equity - “At the Market” Sales Agreement - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 13, 2024
Class of Stock [Line Items]
Net proceeds from issuance of common stock- at-the-market offering	$ 15,392	$ 0
At-The-Market Offering
Class of Stock [Line Items]
Aggregate maximum gross sales proceeds			$ 100,000
Sale of stock, number of shares issued in transaction (in shares)	2,270,712	0
Net proceeds from issuance of common stock- at-the-market offering	$ 14,600

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/exampleRef
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-Subparagraph (d)
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Reference 6: http://www.xbrl.org/2003/role/recommendedDisclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Subparagraph (a)
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (h)
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (c)
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Revenue Arrangements	3 Months Ended
Revenue Arrangements	Mar. 31, 2026
Revenue from Contract with Customer [Abstract]
Revenue Arrangements	Revenue Arrangements Collaboration and license revenue Swedish Orphan Biovitrum AB (publ.) In June 2020, the Company and Sobi entered into the Sobi License, which was subsequently amended in October 2023. Pursuant to the Sobi License, the Company agreed to grant Sobi an exclusive, worldwide (except as to Greater China) license to develop, manufacture and commercialize the Nanoecapsulated Sirolimus plus Pegadricase, or NASP, formerly known as SEL-212, drug candidate , which is currently in development for the treatment of chronic refractory gout. The NASP drug candidate is a pharmaceutical composition containing a combination of a pegylated uricase known as SEL-037, or the Compound, and nanoparticle-encapsulated form of rapamycin, known as ImmTOR. Pursuant to the Sobi License, in consideration of the license, Sobi agreed to pay the Company a one-time, upfront payment of $75.0 million. Sobi has also agreed to make milestone payments totaling up to $630.0 million to the Company upon the achievement of various development and regulatory milestones and, if commercialized, sales thresholds for annual net sales of NASP, and tiered royalty payments ranging from the low double digits on the lowest sales tier to the high teens on the highest sales tier. A more detailed description of the Sobi License and the Company’s evaluation of this agreement under ASC 606 can be found in Note 13, “Revenue Arrangements” to the consolidated financial statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. Any proceeds received from milestone payments or royalties relating to the Sobi License would be required to be distributed to holders of CVRs, net of certain deductions. On June 28, 2024, Sobi initiated a rolling biologics license application to the FDA for NASP for the potential treatment of chronic refractory gout which resulted in the achievement of a development milestone and a $30.0 million payment obligation from Sobi to the Company. As a result, the development milestone was no longer constrained and $30.0 million was recognized as revenue during the year ended December 31, 2024 as there were no remaining performance obligations under the Sobi License. The proceeds from the achievement of the development milestone were received from Sobi in July 2024 and were included, net of deductions as specified in the CVR Agreement, in the distribution to holders of the CVRs in March 2025. Grant revenue National Institute of Neurological Disorders and Stroke of the National Institutes of Health In June 2024, the Company received funding approval from the National Institute of Neurological Disorders and Stroke of the National Institutes of Health, or NINDS, for an award of $1.5 million granted for the budget period, which ran from June 2024 through May 2025. In June 2025, the Company received funding approval from NINDS for an additional award of $1.5 million granted for the budget period that runs from June 2025 through May 2026. The funding was provided by NINDS to further the Company’s use of RNA-based CAR-T cells to combat autoantibody-associated autoimmune disorders. Grant funding is to be used solely for manufacturing of RNA-based CAR-T cells and analysis of samples to inform mechanism of action. The award period runs through May 31, 2026. The Company will recognize grant revenue when expenses reimbursable under the grant have been incurred. As of March 31, 2026 and December 31, 2025, the Company recorded a receivable of $0.1 million and $0.9 million, respectively, that is subject to reimbursement by NINDS. The Company recognized grant revenue of $0.1 million and $0.7 million during the three months ended March 31, 2026 and 2025, respectively. Transaction Price Allocated to Future Performance Obligations Remaining performance obligations represent the transaction price of contracts for which work has not been performed, or has been partially performed. As of March 31, 2026 and December 31, 2025, there were no unsatisfied performance obligations from contracts with customers.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-URI https://asc.fasb.org/1943274/2147479806/606-10-50-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 0.6	$ 0.6

Revenue Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Revenue Arrangements (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Jun. 28, 2024	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Government Assistance Current Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	receivable		receivable
Grant	$ 78	$ 700
Unsatisfied performance obligation	0		$ 0
National Institute of Neurological Disorders and Stroke of the National Institutes of Health Funding
Disaggregation of Revenue [Line Items]
Government assistance, award amount						$ 1,500
Government assistance, potential additional award amount					$ 1,500
Government assistance, asset, current	100		$ 900
Grant	$ 100	$ 700
SOBI \| License
Disaggregation of Revenue [Line Items]
Contract liability							$ 30,000	$ 75,000
Future contingent additional payments								$ 630,000
Revenue recognized				$ 30,000

Equity - Schedule of Authorized Shares of Common Stock for Future Issuance (Details)	Mar. 31, 2026 shares
Class of Stock [Line Items]
Total (in shares)	13,076,508
Shares available for future stock incentive awards
Class of Stock [Line Items]
Total (in shares)	3,641,284
Unvested restricted stock units
Class of Stock [Line Items]
Total (in shares)	736,272
Outstanding common stock options
Class of Stock [Line Items]
Total (in shares)	3,542,407
Series A Preferred Stock
Class of Stock [Line Items]
Total (in shares)	4,026,346
Series B Preferred Stock
Class of Stock [Line Items]
Total (in shares)	437,927
Exercise of warrants
Class of Stock [Line Items]
Total (in shares)	692,272

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Stock Incentive Plans - Schedule of Stock Option Activity (Details) - 2016 Plan, 2018 Inducement Incentive Award Plan and Old Cartesian Plan - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Number of Common Stock Options
Beginning balance (in shares)	2,463,747
Granted (in shares)	1,304,450
Exercised (in shares)	(86,132)
Forfeited (in shares)	(139,658)
Ending balance (in shares)	3,542,407	2,463,747
Vested (in shares)	1,204,110
Vested and expected to vest (in shares)	3,139,038
Weighted-average Exercise Price ($)
Beginning balance (in dollars per share)	$ 13.72
Granted (in dollars per share)	6.81
Exercised (in dollars per share)	3.25
Forfeited (in dollars per share)	15.90
Ending balance (in dollars per share)	11.34	$ 13.72
Vested (in dollars per share)	11.35
Vested and expected to vest (in dollars per share)	$ 11.33
Weighted-average Remaining Contractual Term (in years)
Outstanding, term	7 years 8 months 26 days	6 years 4 months 28 days
Vested, term	5 years 1 month 9 days
Vested and expected to vest, term	7 years 7 months 20 days
Aggregate Intrinsic Value
Outstanding	$ 2,002	$ 2,962
Vested	1,926
Vested and expected to vest	$ 2,002

Equity - Schedule of Warranty Activity (Details)	Mar. 31, 2026 $ / shares shares
Number of Warrants
Number of warrants, outstanding (in shares)	692,272
Weighted-average exercise price
Weighted average exercise price (in dollars per share) \| $ / shares	$ 46.76
Warrant Liability
Number of Warrants
Number of warrants, outstanding (in shares)	685,712
Warrant Liability
Number of Warrants
Number of warrants, outstanding (in shares)	6,560

Stock Incentive Plans

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Stock Incentive Plans

In June 2016, the Company’s stockholders approved the 2016 Incentive Award Plan, or the 2016 Plan, which initially authorized 40,341 shares of common stock for future issuance under the 2016 Plan. Pursuant to the terms of the 2016 Plan, the Board of Directors is authorized to grant awards with respect to common stock, and may delegate to a committee of one or more members of the Board of Directors or executive officers of the Company the authority to grant options and restricted stock units. The Board of Directors established a Stock Option Committee which is authorized to grant awards to certain employees and consultants subject to conditions and limitations within the 2016 Plan. In January 2026, the number of shares of common stock that may be issued under the 2016 Plan was increased by 1,040,444. As of March 31, 2026, 3,044,044 shares remain available for future issuance under the 2016 Plan.

In September 2018, the Company’s 2018 Employment Inducement Incentive Award Plan, or the 2018 Inducement Incentive Award Plan, was adopted by the Board of Directors without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Stock Market LLC listing rules, which initially authorized 39,166 shares of its common stock for issuance. As of March 31, 2026, there are 502,296 shares available for future grant under the 2018 Inducement Incentive Award Plan.

On November 2023, the Company assumed the 2016 Stock Incentive Plan, or the Old Cartesian Plan, of the then private company that merged with the Company in November 2023, or Old Cartesian. . The Old Cartesian Plan permits the granting of options or restricted stock to employees, officers, directors, consultants and advisors to the Company. The unvested common stock options and Series A Preferred Stock options assumed by the Company generally vest over a four-year period. Additionally, the stock options granted have a contractual term of ten years and only full shares can be exercised as per the individual award agreements. As of March 31, 2026, there are 49,149 shares available for future grant under the Old Cartesian Plan.

The outstanding stock options to purchase Old Cartesian common stock were converted into stock options to purchase 776,865 shares of common stock and 14,112.299 shares of Series A Preferred Stock of the Company. The replacement awards that were issued as a part of the assumption of the Old Cartesian Plan resulted in $2.6 million attributed to post-combination

service to be recognized as stock-based compensation expense over the remaining terms of the replacement awards, of which $0.1 million and $0.2 million was recognized during the three months ended March 31, 2026 and 2025, respectively as research and development expense in the consolidated statements of operations and comprehensive loss.

Stock-Based Compensation Expense

Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss, was as follows (in thousands):


	Three Months Ended March 31,
	2026		2025
Research and development	$	949	$	1,275
General and administrative	1,474		1,233
Total stock-based compensation expense	$	2,423	$	2,508

Stock Options

The estimated grant date fair values of stock option awards granted under the 2016 Plan and the 2018 Inducement Incentive Award Plan were calculated using the Black-Scholes option pricing model based on the following weighted-average assumptions:


	Three Months Ended March 31,
	2026			2025
Risk-free interest rate	3.93		%	4.46		%
Dividend yield	—			—
Expected term (in years)	5.97			6.20
Expected volatility	92.71		%	97.44		%
Weighted-average fair value of common stock	$	6.81		$	17.46

The expected term of the Company’s stock options granted has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. Under the simplified method, the expected term is presumed to be the midpoint between the vesting date and the end of the contractual term. The Company utilizes this method due to lack of historical exercise data and the plain nature of its stock-based awards. Expected volatilities are based on the Company’s historical volatility.

The weighted-average grant date fair value of stock options granted during the three months ended March 31, 2026 and 2025 was $5.25 and $14.03, respectively.

As of March 31, 2026, total unrecognized compensation expense related to unvested common stock options was $15.5 million, which is expected to be recognized over a weighted average period of 3.0 years.

The following table summarizes the stock option activity under the 2016 Plan, the 2018 Inducement Incentive Award Plan, and the Old Cartesian Plan for options for common stock:


	Number of Common Stock Options	Weighted-average Exercise Price ($)		Weighted-average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)









Outstanding at December 31, 2025	2,463,747	$	13.72	6.41	$	2,962
Granted	1,304,450	$	6.81
Exercised	(86,132)	$	3.25
Forfeited	(139,658)	$	15.90
Outstanding at March 31, 2026	3,542,407	$	11.34	7.74	$	2,002

Vested at March 31, 2026	1,204,110	$	11.35	5.11	$	1,926
Vested and expected to vest at March 31, 2026	3,139,038	$	11.33	7.64	$	2,002

Restricted Stock Units

During the three months ended March 31, 2026, the Company granted 420,650 restricted stock unit awards with a weighted-average fair value of $6.76 per share based on the closing price of the Company’s common stock on the date of grant under the 2016 Plan, which generally vest over a four-year term. Forfeitures are estimated at the time of grant and are adjusted, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company has estimated a forfeiture rate of 10% for restricted stock unit awards based on historical experience.

Unrecognized compensation expense related to the restricted stock units was $6.4 million as of March 31, 2026, which is expected to be recognized over a weighted-average period of 3.1 years.

The following table summarizes the Company’s restricted stock units under the 2016 Plan and the Old Cartesian Plan:


	Number of Shares	Weighted-average Grant Date Fair Value ($)
Unvested at December 31, 2025	522,498	$	18.44
Granted	420,650	6.76
Vested	(169,278)	18.59

Forfeited	(37,598)	16.61
Unvested at March 31, 2026	736,272	$	11.82

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2026	Apr. 23, 2026
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2026
Document Transition Report	false
Entity File Number	001-37798
Entity Registrant Name	Cartesian Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1622110
Entity Address, Address Line One	7495 New Horizon Way
Entity Address, City or Town	Frederick
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21703
City Area Code	301
Local Phone Number	348-8698
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	RNAC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		29,381,514
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001453687

Leases - Schedule of Other Information Related to Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities:	$ 1,169	$ 317
Weighted-average remaining lease term	3 years 8 months 12 days	4 years 4 months 24 days
Weighted-average discount rate	12.20%	11.80%

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2026
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes As of March 31, 2026, the Company has not recorded any U.S. federal or state income tax benefits for either the net losses the Company has incurred or its earned research and orphan drug credits, due to the uncertainty of realizing a benefit from those items in the future.

- Definition

The entire disclosure for income tax.

+ References

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+ Details

Equity - Warrants - Narrative (Details)	3 Months Ended
Equity - Warrants - Narrative (Details)	Mar. 31, 2026 shares
Equity [Abstract]
Warrants issued (in shares)	0
Warrants exercised (in shares)	0
Warrants cancelled (in shares)	0

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2026
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Fair Value Measurements - Schedule of Fair Value Measurement Inputs and Valuation Techniques for CVR Liability (Details) - Level 3	Mar. 31, 2026	Dec. 31, 2025
Estimated probability of success \| Minimum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent value right liability, measurement input	0.950	0.950
Estimated probability of success \| Maximum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent value right liability, measurement input	1.000	1.000
Expected volatility of future revenues
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent value right liability, measurement input	0.230	0.230

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Payables and Accruals [Abstract]
Payroll and employee related expenses	$ 1,319	$ 3,985
Collaboration and licensing	385	320
Accrued patent fees	195	205
Accrued research and development costs	4,858	2,521
Accrued professional and consulting services	2,187	2,059
Accrued equity offering costs	707	30
Other	510	378
Accrued expenses	$ 10,161	$ 9,498

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As of March 31, 2026, the Company was not a party to any litigation that could have a material adverse effect on the Company’s business, financial position, results of operations or cash flows. Other As permitted under Delaware law, the Company indemnifies its officers, directors, consultants and employees for certain events or occurrences that happen by reason of the relationship with, or position held at the Company. Through March 31, 2026, the Company had not experienced any losses related to these indemnification obligations, and no claims were outstanding. The Company does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established. Additionally, as permitted under Delaware law, the Company indemnifies its directors for certain events or occurrences while the director is, or was, serving at the Company’s request in such capacity. The term of the indemnification is for the director’s lifetime. The maximum potential amount of future payments the Company could be required to make is unlimited; however, the Company has directors’ insurance coverage that limits its exposure and enables it to recover a portion of any future amounts paid. The Company also has indemnification arrangements under certain of its facility leases that require it to indemnify the landlord against certain costs, expenses, fines, suits, claims, demands, liabilities, and actions directly resulting from certain breaches, violations, or non-performance of any covenant or condition of the Company’s lease. The term of the indemnification is for the term of the related lease agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited. To date, the Company had not experienced any material losses related to any of its indemnification obligations, and no material claims with respect thereto were outstanding.

Stock Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss, was as follows (in thousands):


	Three Months Ended March 31,
	2026		2025
Research and development	$	949	$	1,275
General and administrative	1,474		1,233
Total stock-based compensation expense	$	2,423	$	2,508

Schedule of Weighted Average Assumptions Used


	Three Months Ended March 31,
	2026			2025
Risk-free interest rate	3.93		%	4.46		%
Dividend yield	—			—
Expected term (in years)	5.97			6.20
Expected volatility	92.71		%	97.44		%
Weighted-average fair value of common stock	$	6.81		$	17.46

Schedule of Options Activity

The following table summarizes the stock option activity under the 2016 Plan, the 2018 Inducement Incentive Award Plan, and the Old Cartesian Plan for options for common stock:


	Number of Common Stock Options	Weighted-average Exercise Price ($)		Weighted-average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)









Outstanding at December 31, 2025	2,463,747	$	13.72	6.41	$	2,962
Granted	1,304,450	$	6.81
Exercised	(86,132)	$	3.25
Forfeited	(139,658)	$	15.90
Outstanding at March 31, 2026	3,542,407	$	11.34	7.74	$	2,002

Vested at March 31, 2026	1,204,110	$	11.35	5.11	$	1,926
Vested and expected to vest at March 31, 2026	3,139,038	$	11.33	7.64	$	2,002

Schedule of Restricted Stock Units Activity

The following table summarizes the Company’s restricted stock units under the 2016 Plan and the Old Cartesian Plan:


	Number of Shares	Weighted-average Grant Date Fair Value ($)
Unvested at December 31, 2025	522,498	$	18.44
Granted	420,650	6.76
Vested	(169,278)	18.59

Forfeited	(37,598)	16.61
Unvested at March 31, 2026	736,272	$	11.82

Property and Equipment

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment consists of the following (in thousands):


	March 31, 2026		December 31, 2025
Laboratory equipment	$	9,323	$	8,419
Computer equipment and software	417		417
Leasehold improvements	6,709		4,177
Furniture and fixtures	307		269
Office equipment	170		170
Construction in process	59		3,466
Total property and equipment	16,985		16,918
Less: Accumulated depreciation	(5,348)		(4,733)
Property and equipment, net	$	11,637	$	12,185

Depreciation expense was $0.6 million for each of the three months ended March 31, 2026 and 2025, respectively.

Equity - Preferred Stock - Narrative (Details) - shares	Mar. 31, 2026	Dec. 31, 2025
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	120,790.402	120,790.402
Preferred stock, shares issued (in shares)	120,790.402	120,790.402
Convertible preferred stock, common stock issuable upon conversion (in shares)	4,464,273
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)	437,927	437,927
Preferred stock, shares issued (in shares)	437,927	437,927

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Stock Incentive Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2026	Mar. 31, 2026	Mar. 31, 2025	Nov. 13, 2023	Sep. 30, 2018	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total (in shares)		13,076,508
Stock‑based compensation expense		$ 2,423	$ 2,508
Weighted average grant date fair value of stock options (in dollars per share)		$ 5.25	$ 14.03
Outstanding Series A Preferred Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total (in shares)		3,542,407
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting term		4 years
Weighted average period		3 years 1 month 6 days
Granted (in shares)		420,650
Granted (in dollars per share)		$ 6.76
Estimated forfeitures rate		10.00%
Unrecognized compensation expense		$ 6,400
Common stock \| Outstanding Series A Preferred Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested employee stock options		$ 15,500
Weighted average period		3 years
2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)						40,341
Number of shares authorized, increase (in shares)	1,040,444
Total (in shares)		3,044,044
Employment Inducement Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)		502,296
Total (in shares)					39,166
Old Cartesian Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)		49,149
Award vesting term		4 years
Award expiration term		10 years
Unrecognized compensation expense related to unvested employee stock options				$ 2,600
Stock‑based compensation expense		$ 100	$ 200
Old Cartesian Plan \| Old Cartestian \| Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, number (in shares)				776,865
Old Cartesian Plan \| Old Cartestian \| Preferred stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, number (in shares)				14,112.299

Stock Incentive Plans - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 2,423	$ 2,508
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	949	1,275
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 1,474	$ 1,233

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Current assets:
Cash and cash equivalents	$ 118,641	$ 125,139
Accounts receivable	261	1,115
Prepaid expenses and other current assets	3,137	3,022
Total current assets	122,039	129,276
Property and equipment, net	11,637	12,185
Right-of-use assets, net	5,366	5,601
In-process research and development asset	93,900	93,900
Goodwill	48,163	48,163
Long-term restricted cash	1,735	1,735
Long-term prepaid expenses and other assets	5,551	5,551
Total assets	288,391	296,411
Current liabilities:
Accounts payable	1,598	1,288
Accrued expenses and other current liabilities	10,161	9,498
Lease liabilities	4,186	4,151
Total current liabilities	15,945	14,937
Lease liabilities, net of current portion	7,669	8,525
Warrant liability	47	141
Contingent value right liability	405,900	392,100
Deferred tax liabilities, net	6,948	6,948
Total liabilities	436,509	422,651
Commitments and contingencies (Note 14)
Stockholders’ deficit:
Preferred stock, value, issued	0	0
Common stock, $0.0001 par value; 350,000,000 shares authorized as of March 31, 2026 and December 31, 2025; 28,544,728 and 26,011,106 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively	3	3
Additional paid-in capital	718,017	700,706
Accumulated deficit	(861,555)	(822,373)
Accumulated other comprehensive loss	(4,583)	(4,576)
Total stockholders’ deficit	(148,118)	(126,240)
Total liabilities and stockholders’ deficit	288,391	296,411
Series A Preferred Stock
Stockholders’ deficit:
Preferred stock, value, issued	0	0
Series B Preferred Stock
Stockholders’ deficit:
Preferred stock, value, issued	$ 0	$ 0

Stock Incentive Plans - Schedule of Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2026 $ / shares shares
Number of Shares
Unvested at beginning of period (in shares) \| shares	522,498
Granted (in shares) \| shares	420,650
Vested (in shares) \| shares	(169,278)
Forfeited (in shares) \| shares	(37,598)
Unvested at end of period (in shares) \| shares	736,272
Weighted-average Grant Date Fair Value ($)
Unvested at beginning of period (in dollars per share) \| $ / shares	$ 18.44
Granted (in dollars per share) \| $ / shares	6.76
Vested (in dollars per share) \| $ / shares	18.59
Forfeited (in dollars per share) \| $ / shares	16.61
Unvested at end of period (in dollars per share) \| $ / shares	$ 11.82

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Revenue:
Collaboration and license	$ 0	$ 400
Grant	78	700
Total revenues	78	1,100
Operating expenses:
Research and development	19,463	14,674
General and administrative	7,114	8,315
Total operating expenses	26,577	22,989
Operating loss	(26,499)	(21,889)
Other (expense) income:
Interest income	1,026	2,015
Gain on change in fair value of warrant liabilities	94	1,818
(Loss) gain on change in fair value of contingent value right liability	(13,800)	346
Other expense, net	(3)	0
Total other (expense) income, net	(12,683)	4,179
Net loss	(39,182)	(17,710)
Other comprehensive (loss) income:
Foreign currency translation adjustment	(7)	32
Total comprehensive loss	$ (39,189)	$ (17,678)
Net loss per share allocable to common stockholders:
Basic (in dollars per share)	$ (1.46)	$ (0.68)
Diluted (in dollars per share)	$ (1.46)	$ (0.68)
Weighted-average common shares outstanding:
Basic (in shares)	26,855,158	25,902,650
Diluted (in shares)	26,855,158	25,902,650

Equity

3 Months Ended

Mar. 31, 2026

Equity [Abstract]

Equity

Equity Financings

“At the Market” Sales Agreement

On December 13, 2024, the Company entered into a Sales Agreement, or the Sales Agreement, with Leerink Partners LLC to sell shares of the Company’s common stock, from time to time, through an “at the market” equity offering program under which Leerink Partners LLC will act as sales agent. The shares of common stock sold pursuant to the Sales Agreement will be issued pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333-283803), filed on December 13, 2024 with the SEC and related prospectus supplement, filed on January 8, 2025 with the SEC, for aggregate gross sales proceeds of up to $100.0 million.

During the three months ended March 31, 2026, the Company sold 2,270,712 shares of its common stock pursuant to the Sales Agreement for net proceeds of approximately $14.6 million after commissions and expenses. There were no shares sold pursuant to the Sales Agreement during the three months ended March 31, 2025.

Warrants

During the three months ended March 31, 2026, there were no warrants issued, exercised, or cancelled. The following is a summary of the Company’s warrants as of March 31, 2026:


	Number of Warrants
	Equity classified	Liability classified	Total	Weighted-average exercise price




Outstanding at March 31, 2026	6,560	685,712	692,272	$	46.76

See Note 11, “Equity” to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 for further discussion of the terms related to the Company’s warrants.

Preferred Stock

As of March 31, 2026, the Company had 120,790.402 shares of Series A Preferred Stock and 437,927 shares of Series B Preferred Stock issued and outstanding, respectively, which are convertible into 4,464,273 shares of common stock.

Reserved Shares

The Company has authorized shares of common stock for future issuance as of March 31, 2026 as follows:


			March 31, 2026
Exercise of warrants			692,272
Shares available for future stock incentive awards			3,641,284

Unvested restricted stock units			736,272
Outstanding common stock options			3,542,407
Series A Preferred Stock			4,026,346
Series B Preferred Stock			437,927

Total			13,076,508

- Definition

The entire disclosure for equity.

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+ Details

Accrued Expenses

3 Months Ended

Mar. 31, 2026

Payables and Accruals [Abstract]

Accrued Expenses

Accrued expenses consist of the following (in thousands):


	March 31, 2026		December 31, 2025
Payroll and employee related expenses	$	1,319	$	3,985
Collaboration and licensing	385		320
Accrued patent fees	195		205
Accrued research and development costs	4,858		2,521
Accrued professional and consulting services	2,187		2,059


Accrued equity offering costs	707		30
Other	510		378
Accrued expenses	$	10,161	$	9,498

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2026
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events through the date on which the consolidated financial statements were issued. The Company has concluded that no subsequent events have occurred that require disclosure.

Collaboration and License Agreements - National Cancer Institute of the National Institutes of Health - Narrative (Details) - NCI Agreement $ in Millions	Sep. 16, 2019 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License and option agreement, royalty payment	$ 0.1
License and option agreement, benchmark royalties, maximum	$ 0.8
Written notice for agreement termination	60 days

Fair Value Measurements - Narrative (Details)	3 Months Ended	12 Months Ended
Fair Value Measurements - Narrative (Details)	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability, transfers, net	$ 0	$ 0
Fair value, measurement with unobservable inputs reconciliation, recurring basis, asset, transfers, net	$ 0	$ 0
Dividend yield \| Valuation technique, option pricing model
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants and rights outstanding, measurement input	0

Goodwill and Indefinite-Lived Intangible Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Business Combination [Line Items]
Goodwill	$ 48,163,000		$ 48,163,000
Intangible assets	93,900,000		$ 93,900,000
In Process Research and Development
Business Combination [Line Items]
Impairment to goodwill	0	$ 0
Old Cartesian
Business Combination [Line Items]
Goodwill	48,200,000
Old Cartesian \| Descartes-08 for MG
Business Combination [Line Items]
Intangible assets	$ 93,900,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 14: http://www.xbrl.org/2009/role/commonPracticeRef
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-Paragraph 4
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+ Details

Collaboration and License Agreements - Biogen M.A., Inc. - Narrative (Details)	Sep. 08, 2023
Biogen M.A., Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Written notice for agreement termination	30 days

Fair Value Measurements

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following tables present the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2026 and December 31, 2025 (in thousands):


	March 31, 2026
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds (included in cash equivalents)	$	117,674	$	117,674	$	—	$	—





Total assets	$	117,674	$	117,674	$	—	$	—

Liabilities:
Warrant liability	$	47	$	—	$	—	$	47
Contingent value right liability	405,900		—		—		405,900
Total liabilities	$	405,947	$	—	$	—	$	405,947


	December 31, 2025
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds (included in cash equivalents)	$	122,724	$	122,724	$	—	$	—





Total assets	$	122,724	$	122,724	$	—	$	—

Liabilities:
Warrant liability	$	141	$	—	$	—	$	141
Contingent value right liability	392,100		—		—		392,100

Total liabilities	$	392,241	$	—	$	—	$	392,241

There were no transfers within the fair value hierarchy during the three months ended March 31, 2026 or the year ended December 31, 2025.

Cash, Cash Equivalents, and Restricted Cash

As of March 31, 2026 and December 31, 2025, money market funds were classified as cash and cash equivalents on the accompanying consolidated balance sheets as they mature within 90 days from the date of purchase.

As of March 31, 2026, the Company had restricted cash balances relating to secured letters of credit in connection with its real estate leases. The Company’s consolidated statements of cash flows include the following as of March 31, 2026 and 2025 (in thousands):


	March 31,
	2026		2025
Cash and cash equivalents	$	118,641	$	180,434

Long-term restricted cash	1,735		1,669
Total cash, cash equivalents, and restricted cash	$	120,376	$	182,103

Warrants to Purchase Common Stock

In April 2022, the Company issued warrants in connection with an underwritten offering, or the 2022 Warrants. Pursuant to the terms of the 2022 Warrants, the Company could be required to settle the 2022 Warrants in cash in the event of an acquisition of the Company under certain circumstances and, as a result, the 2022 Warrants are required to be measured at fair value and reported as a liability on the balance sheet.

The Company recorded the fair value of the 2022 Warrants upon issuance using the Black-Scholes valuation model and is required to revalue the 2022 Warrants at each reporting date, with any changes in fair value recorded in the statements of operations and comprehensive loss. The valuation of the 2022 Warrants is classified as Level 3 of the fair value hierarchy due to the need to use assumptions in the valuation that are both significant to the fair value measurement and unobservable,

including the stock price volatility and the expected life of the 2022 Warrants. Generally, increases (decreases) in the fair value of the underlying stock and estimated term would result in a directionally similar impact to the fair value measurement.

The estimated fair value of the 2022 Warrants was determined using the following inputs to the Black-Scholes simulation valuation:

•Estimated fair value of the underlying stock. The Company estimates the fair value of the common stock based on the closing stock price at the end of each reporting period.

•Risk-free interest rate. The risk-free interest rate is based on the U.S. Treasury at the valuation date commensurate with the expected remaining life assumption.

•Dividend rate. The dividend rate is based on the historical rate, which the Company anticipates will remain at zero.

•Expected life. The expected life of the 2022 Warrants is assumed to be equivalent to their remaining contractual term which expires on April 11, 2027.

•Volatility. The Company estimates stock price volatility based on the Company’s historical volatility for a period of time commensurate with the expected remaining life of the 2022 Warrants.

A summary of the Black-Scholes pricing model assumptions used to record the fair value of the 2022 Warrants liability is as follows:


	March 31, 2026		December 31, 2025
Risk-free interest rate	3.68	%	3.48	%
Dividend yield	—		—
Expected life (in years)	1.03		1.28
Expected volatility	89.14	%	87.36	%

The following table reflects a roll-forward of fair value for the Company’s Level 3 warrant liabilities (see Note 9, “Equity” to these unaudited consolidated financial statements) for the three months ended March 31, 2026 (in thousands):


	Warrant Liability
Fair value as of December 31, 2025	$	141


Change in fair value	(94)
Fair value as of March 31, 2026	$	47

Contingent Value Right

In December 2023, the Company entered into a contingent value rights agreement, or the CVR Agreement, pursuant to which each holder of common stock or a 2022 Warrant in December 2023 was distributed a CVR by the Company. Each CVR entitles its holder to distributions of milestone and royalty payments under the Sobi License, net of deductions. See Note 6, “Fair Value Measurements” to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 for further discussion of the terms related to the CVR Agreement.

The CVRs represent financial instruments that are accounted for under the fair value option election in ASC 825, Financial Instruments, or ASC 825. Under the fair value option election, the CVRs are initially measured at the aggregate estimated fair value of the CVRs and will be subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. The estimated fair value of the CVR liability was determined using a Monte Carlo simulation model to estimate future cash flows associated with the legacy assets, including the expected milestone and royalty payments under the Sobi License, net of deductions. Changes in fair value of the CVR liability are presented in the consolidated statements of operations and comprehensive loss. The liability value is based on significant inputs not observable in the market such as estimated cash flows, estimated probabilities of success, and expected volatility of future revenues, which represent a Level 3 measurement within the fair value hierarchy. The significant inputs used to estimate the fair value of the CVR liability, which represented a financial instrument being accounted for under the fair value option, were as follows:


	March 31, 2026		December 31, 2025
Estimated cash flow dates	2026 - 2038		2026 - 2037
Estimated probability of success	95.0% - 100.0%		95.0% - 100.0%
Expected volatility of future revenues	23.0	%	23.0	%

The following table reflects a roll-forward of fair value for the Company’s Level 3 CVR liability for the three months ended March 31, 2026 (in thousands):


	CVR Liability
Fair value as of December 31, 2025	$	392,100


Change in fair value	13,800
Fair value as of March 31, 2026	$	405,900

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
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-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Section 50
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Description of the Business	3 Months Ended
Description of the Business	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.

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Cash flows from operating activities
Net loss	$ (39,182)	$ (17,710)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	615	1,156
Non‑cash lease expense	235	184
Stock‑based compensation expense	2,423	2,508
Gain on change in warrant liability	(94)	(1,818)
Loss (gain) on change in fair value of CVR liability	13,800	(346)
Changes in operating assets and liabilities:
Accounts receivable	854	(893)
Prepaid expenses and other assets	(246)	(5,830)
Accounts payable	310	1,819
Accrued expenses and other liabilities	(850)	(2,178)
Net cash used in operating activities	(22,135)	(23,108)
Cash flows from investing activities
Purchases of property and equipment	(27)	(1,075)
Net cash used in investing activities	(27)	(1,075)
Cash flows from financing activities
Equity offering costs	0	(454)
Proceeds from exercise of stock options	279	183
Proceeds from at the market offering, net of commissions and expenses	15,392	0
Distribution of Contingent Value Rights	0	(7,754)
Net cash provided by (used in) financing activities	15,671	(8,025)
Effect of exchange rate changes on cash	(7)	32
Net change in cash, cash equivalents, and restricted cash	(6,498)	(32,176)
Cash, cash equivalents and restricted cash at beginning of period	126,874	214,279
Cash, cash equivalents and restricted cash at end of period	120,376	182,103
Non-cash investing and financing activities
Purchase of property and equipment not yet paid	59	535
Equity offering costs in accrued liabilities	$ 707	$ 0

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2026	Dec. 31, 2025
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	9,427,168.437	9,427,168.437
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	28,544,728	26,011,106
Common stock, shares outstanding (in shares)	28,544,728	26,011,106
Series A Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	134,904.563	134,904.563
Preferred stock, shares issued (in shares)	120,790.402	120,790.402
Preferred stock, shares outstanding (in shares)	120,790.402	120,790.402
Series B Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	437,927	437,927
Preferred stock, shares issued (in shares)	437,927	437,927
Preferred stock, shares outstanding (in shares)	437,927	437,927

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2026

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following (in thousands):


	March 31, 2026		December 31, 2025
Payroll and employee related expenses	$	1,319	$	3,985
Collaboration and licensing	385		320
Accrued patent fees	195		205
Accrued research and development costs	4,858		2,521
Accrued professional and consulting services	2,187		2,059


Accrued equity offering costs	707		30
Other	510		378
Accrued expenses	$	10,161	$	9,498

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables present the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2026 and December 31, 2025 (in thousands):


	March 31, 2026
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds (included in cash equivalents)	$	117,674	$	117,674	$	—	$	—





Total assets	$	117,674	$	117,674	$	—	$	—

Liabilities:
Warrant liability	$	47	$	—	$	—	$	47
Contingent value right liability	405,900		—		—		405,900
Total liabilities	$	405,947	$	—	$	—	$	405,947


	December 31, 2025
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds (included in cash equivalents)	$	122,724	$	122,724	$	—	$	—





Total assets	$	122,724	$	122,724	$	—	$	—

Liabilities:
Warrant liability	$	141	$	—	$	—	$	141
Contingent value right liability	392,100		—		—		392,100

Total liabilities	$	392,241	$	—	$	—	$	392,241

Schedule of Cash and Cash Equivalents

The Company’s consolidated statements of cash flows include the following as of March 31, 2026 and 2025 (in thousands):


	March 31,
	2026		2025
Cash and cash equivalents	$	118,641	$	180,434

Long-term restricted cash	1,735		1,669
Total cash, cash equivalents, and restricted cash	$	120,376	$	182,103

Schedule of Restricted Cash

The Company’s consolidated statements of cash flows include the following as of March 31, 2026 and 2025 (in thousands):


	March 31,
	2026		2025
Cash and cash equivalents	$	118,641	$	180,434

Long-term restricted cash	1,735		1,669
Total cash, cash equivalents, and restricted cash	$	120,376	$	182,103

Schedule of Fair Value Measurement Inputs and Valuation Techniques for 2022 Warrants Liability and CVR Liability

A summary of the Black-Scholes pricing model assumptions used to record the fair value of the 2022 Warrants liability is as follows:


	March 31, 2026		December 31, 2025
Risk-free interest rate	3.68	%	3.48	%
Dividend yield	—		—
Expected life (in years)	1.03		1.28
Expected volatility	89.14	%	87.36	%

The significant inputs used to estimate the fair value of the CVR liability, which represented a financial instrument being accounted for under the fair value option, were as follows:


	March 31, 2026		December 31, 2025
Estimated cash flow dates	2026 - 2038		2026 - 2037
Estimated probability of success	95.0% - 100.0%		95.0% - 100.0%
Expected volatility of future revenues	23.0	%	23.0	%

Schedule of Roll-Forward of Fair Value for the Company’s Level 3 Warrant Liabilities, CVR Liability and Forward Contract Liabilities


	Warrant Liability
Fair value as of December 31, 2025	$	141


Change in fair value	(94)
Fair value as of March 31, 2026	$	47

The following table reflects a roll-forward of fair value for the Company’s Level 3 CVR liability for the three months ended March 31, 2026 (in thousands):


	CVR Liability
Fair value as of December 31, 2025	$	392,100


Change in fair value	13,800
Fair value as of March 31, 2026	$	405,900

Collaboration and License Agreements	3 Months Ended
Collaboration and License Agreements	Mar. 31, 2026
Goodwill and Intangible Assets Disclosure [Abstract]
Collaboration and License Agreements	Collaboration and License Agreements Biogen MA, Inc. On September 8, 2023, the Company entered into a non-exclusive, sublicensable, worldwide, perpetual patent license agreement, or the Biogen Agreement, with Biogen MA, Inc., or Biogen, to research, develop, make, use, offer, sell and import products or processes containing or using an engineering T-cell modified with an mRNA comprising, or encoding a protein comprising, certain sequences licensed under the Biogen Agreement for the prevention, treatment, palliation and management of autoimmune diseases and disorders, excluding cancers, neoplastic disorders, and paraneoplastic disorders. The Company is not obligated to pay Biogen any expenses, fees, or royalties. The Company may terminate the Biogen Agreement for any reason or no reason, and Biogen may terminate the agreement after a notice-and-cure period of 30 days if the Company fails to pay a fee owed to Biogen or for any other material breach of the agreement. The Biogen Agreement will otherwise expire when all claims of all issued patents within the patents and patent applications licensed to the Company under the Biogen Agreement have expired or been finally rendered revoked, invalid or unenforceable by a decision of a court or government agency. The Biogen Agreement encompasses patents and patent applications in the PCT/US2010/026825 patent family, which was filed March 10, 2010. In general, all patents that issue in this family have an expected expiration date of March 10, 2030, subject to potential patent term adjustments and/or extensions. For the U.S. patents and applications in this family, U.S. Patent 9,034,324 was awarded 677 days of patent term adjustment, which would extend the expiration date of this patent to January 16, 2032, absent any challenges to the patent term. The other issued patent in this family was not awarded any patent term adjustment, so its expected expiration date is March 10, 2030. National Cancer Institute of the National Institutes of Health Effective September 16, 2019, the Company entered into a nonexclusive, worldwide license agreement, or the NCI Agreement, with the U.S. Department of Health and Human Services, represented by the National Cancer Institute of the National Institutes of Health, or NCI. Under the NCI Agreement, the Company was granted a license under certain NCI patents and patent applications designated in the agreement, to make, use, sell, offer and import products and processes within the scope of the patents and applications licensed under the NCI Agreement when developing and manufacturing anti-BCMA CAR-T cell products for the treatment of MG pemphigus vulgaris, and immune thrombocytopenic purpura according to methods designated in the NCI Agreement. In connection with the Company’s entry into the NCI Agreement, Old Cartesian paid to NCI a one-time $0.1 million license royalty payment. Under the NCI Agreement, the Company is further required to pay NCI a low five-digit annual royalty. The Company must also pay earned royalties on net sales in a low single-digit percentage and pay up to $0.8 million in benchmark royalties upon the Company’s achievement of designated benchmarks that are based on the commercial development plan agreed between the parties. Under the NCI Agreement, the Company must use reasonable commercial efforts to bring licensed products and licensed processes to the point of Practical Application (as defined in the NCI Agreement). Upon the Company’s first commercial sale, the Company must use reasonable commercial efforts to make licensed products and licensed processes reasonably accessible to the United States public. After the Company’s first commercial sale, the Company must make reasonable quantities of licensed products or materials produced via licensed processes available to patient assistance programs and develop educational materials detailing the licensed products. Unless the Company obtains a waiver from NCI, the Company must have licensed products and licensed processes manufactured substantially in the United States. Prior to the first commercial sale, upon NCI’s request, the Company is obligated to provide NCI with commercially reasonable quantities of licensed products made through licensed processes to be used for in vitro research. Additionally, the Company must use reasonable commercial efforts to submit a BLA with respect to a licensed product by the fourth quarter of 2026 and make a first commercial sale of a licensed product by the fourth quarter of 2028. The NCI Agreement terminates upon the expiration of the last to expire of the patent rights licensed thereunder, if not sooner terminated. The NCI Agreement encompasses patents and patent applications in the PCT/US2013/032029 patent family, which was filed March 15, 2013. In general, all patents that issue in this family have an expected expiration of March 15, 2033, subject to potential patent term adjustments and/or extensions. For the U.S. patents and applications in this family, only two patents were awarded patent term adjustments. U.S. Patent 9,765,342 was awarded 297 days of patent term adjustment, which would extend the expiration date of this patent to January 6, 2034, absent any challenges to the patent term. The other patent, U.S. Patent 10,876,123, was awarded three days of patent term adjustment, but this patent is subject to terminal disclaimers filed against other family members, so this patent will not extend beyond the March 15, 2033 date. The other issued patents in this family were not awarded any patent term adjustment, so the expected expiration date for these patents also remains March 15, 2033. There is also a pending patent application which, if issued, will expire on March 15, 2033, but could also be subject to patent term adjustment and to any potential future terminal disclaimers. NCI has the right to terminate the NCI Agreement, after giving written notice and providing a cure period in accordance with its terms, if the Company is in default of a material obligation. The Company has the unilateral right to terminate the agreement in any country or territory by giving NCI 60 days’ written notice. The Company agreed to indemnify NCI against any liability arising out of the Company’s, sublicensees’ or third parties’ use of the licensed patent rights and licensed products or licensed processes developed in connection with the licensed patent rights. Shenyang Sunshine Pharmaceutical Co., Ltd In May 2014, the Company entered into a license agreement, or the 3SBio License, with Shenyang Sunshine Pharmaceutical Co., Ltd., or 3SBio. The Company has paid to 3SBio an aggregate of $7.0 million in upfront and milestone-based payments under the 3SBio License as of March 31, 2026. The Company is required to make future payments to 3SBio contingent upon the occurrence of events related to the achievement of clinical and regulatory approval milestones of up to an aggregate of $15.0 million for products containing the Company’s ImmTOR platform.

Property and Equipment (Tables)

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consists of the following (in thousands):


	March 31, 2026		December 31, 2025
Laboratory equipment	$	9,323	$	8,419
Computer equipment and software	417		417
Leasehold improvements	6,709		4,177
Furniture and fixtures	307		269
Office equipment	170		170
Construction in process	59		3,466
Total property and equipment	16,985		16,918
Less: Accumulated depreciation	(5,348)		(4,733)
Property and equipment, net	$	11,637	$	12,185

Consolidated Statements of Changes in Stockholders’ Deficit - USD ($) $ in Thousands	Total	Series A Preferred Stock	Series B Preferred Stock	Preferred stock Series A Preferred Stock	Preferred stock Series B Preferred Stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Preferred stock, beginning balance (in shares) at Dec. 31, 2024				120,790.402	437,927
Beginning balance at Dec. 31, 2024	$ (6,802)			$ 0	$ 0	$ 3	$ 689,887	$ (692,071)	$ (4,621)
Common stock, beginning balance (in shares) at Dec. 31, 2024						25,767,369
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of options (in shares)						55,690
Issuance of common stock upon exercise of options	183						183
Issuance of common stock upon vesting of restricted stock units (in shares)						113,042
Stock-based compensation expense	2,508						2,508
Currency translation adjustment	32								32
Net loss	(17,710)							(17,710)
Preferred stock, ending balance (in shares) at Mar. 31, 2025				120,790.402	437,927
Ending balance at Mar. 31, 2025	$ (21,789)			$ 0	$ 0	$ 3	692,578	(709,781)	(4,589)
Common stock, ending balance (in shares) at Mar. 31, 2025						25,936,101
Preferred stock, beginning balance (in shares) at Dec. 31, 2025	0	120,790.402	437,927	120,790.402	437,927
Beginning balance at Dec. 31, 2025	$ (126,240)			$ 0	$ 0	$ 3	700,706	(822,373)	(4,576)
Common stock, beginning balance (in shares) at Dec. 31, 2025	26,011,106					26,011,106
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of options (in shares)						93,632
Issuance of common stock upon exercise of options	$ 304						304
Issuance of common stock upon vesting of restricted stock units (in shares)						169,278
Issuance of common stock through at the market offering, net of commissions and expenses (in shares)						2,270,712
Issuance of common stock through at the market offering, net of commissions and expenses	14,584						14,584
Stock-based compensation expense	2,423						2,423
Currency translation adjustment	(7)								(7)
Net loss	$ (39,182)							(39,182)
Preferred stock, ending balance (in shares) at Mar. 31, 2026	0	120,790.402	437,927	120,790.402	437,927
Ending balance at Mar. 31, 2026	$ (148,118)			$ 0	$ 0	$ 3	$ 718,017	$ (861,555)	$ (4,583)
Common stock, ending balance (in shares) at Mar. 31, 2026	28,544,728					28,544,728

Description of the Business (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Cash and Cash Equivalents [Line Items]
Accumulated deficit	$ (861,555)	$ (822,373)
Cash, cash equivalents, restricted cash and marketable securities	120,400
Restricted cash and cash equivalents	$ 1,700
Old Cartesian
Cash and Cash Equivalents [Line Items]
Contingent value right, percentage of milestone payments, royalties and other amounts to be distributed	100.00%

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Stock Incentive Plans - Schedule of Weighted Average Assumptions Used (Details) - Options - $ / shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	3.93%	4.46%
Dividend yield	0.00%	0.00%
Expected term (in years)	5 years 11 months 19 days	6 years 2 months 12 days
Expected volatility	92.71%	97.44%
Weighted-average fair value of common stock (in dollars per share)	$ 6.81	$ 17.46

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Segment Reporting

3 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

Segment Reporting

The following table presents selected financial information with respect to the Company’s single operating segment for the three months ended March 31, 2026 and 2025 (in thousands):


	Three Months Ended March 31,
	2026		2025
Revenue:
Collaboration and license revenue	$	—	$	400
Grant revenue	78		700
Total revenue	78		1,100
Less:
Operating expenses:

Descartes-08 for MG	12,135		7,036
Descartes-08 for dermatomyositis	227		—
Early stage programs	355		990
Research and development employee expenses	3,828		3,702
Research and development stock-based compensation expense	949		1,275
Research and development facilities and other expenses	1,969		1,671
General and administrative	7,114		8,315

Other expense (income), net (1)	12,683		(4,179)
Net loss	$	(39,182)	$	(17,710)


(1) Includes interest income; gain on change in fair value of warrant liabilities; (loss) gain on change in fair value of contingent value right liability; and other expense, net.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
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-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

+ Details