Related Parties	9 Months Ended
Sep. 30, 2025
Related Party Transactions [Abstract]
Related Parties	15. Related Parties Samsara BioCapital L.P. and Affiliates Since the Company’s inception, Samsara has provided in-kind research and development and general and administrative services to the Company. From April 2022, Samsara also began to provide general and administrative services for cash consideration related to (i) accounting and controllership, (ii) human resources, and (iii) executive assistance. In July 2023, the Company and Samsara entered into a Business Services Agreement (the “BSA”) that governs the provision of such services. The BSA has a term of five years and may be terminated upon 15 days written notice by either party. The Company recognized $0.1 million for each of the three months ended September 30, 2025 and 2024, and $0.3 million and $0.1 million for the nine months ended September 30, 2025 and 2024, respectively, as general and administrative expenses, related to the services provided by Samsara under the BSA. The Company recognized immaterial amounts for the three and nine months ended September 30, 2025 and 2024 as research and development expenses, related to the services provided by Samsara under the BSA. In-kind services of $0.1 million were estimated at fair value and recognized as capital contributions to additional paid-in capital for the nine months ended September 30, 2024. There was no capital contribution recognized for the three months ended September 30, 2024. Samsara stopped providing in-kind services in July 2024. As of September 30, 2025 and December 31, 2024, the Company recognized $0.1 million in accrued expenses and other current liabilities in the condensed consolidated balance sheets related to the services provided by Samsara under the BSA. As of September 30, 2025 and December 31, 2024, the Company recognized immaterial amounts in accounts payable in the condensed consolidated balance sheets related to the services provided by Samsara under the BSA. The Company recognized a $32.1 million royalty obligation - related party, as a long-term liability, under the Royalty Agreement as of September 30, 2025 and as of December 31, 2024. The Company issued Samsara convertible promissory notes (Note 8), redeemable convertible preferred stock and common stock. In July 2024, the Company entered into a Royalty Agreement with Samsara (Note 7).

Related Parties

9 Months Ended

Sep. 30, 2025

15. Related Parties

Samsara BioCapital L.P. and Affiliates

Since the Company’s inception, Samsara has provided in-kind research and development and general and administrative services to the Company. From April 2022, Samsara also began to provide general and administrative services for cash consideration related to (i) accounting and controllership, (ii) human resources, and (iii) executive assistance. In July 2023, the Company and Samsara entered into a Business Services Agreement (the “BSA”) that governs the provision of such services. The BSA has a term of five years and may be terminated upon 15 days written notice by either party.

The Company recognized $0.1 million for each of the three months ended September 30, 2025 and 2024, and $0.3 million and $0.1 million for the nine months ended September 30, 2025 and 2024, respectively, as general and administrative expenses, related to the services provided by Samsara under the BSA. The Company recognized immaterial amounts for the three and nine months ended September 30, 2025 and 2024 as research and development expenses, related to the services provided by Samsara under the BSA.

In-kind services of $0.1 million were estimated at fair value and recognized as capital contributions to additional paid-in capital for the nine months ended September 30, 2024. There was no capital contribution recognized for the three months ended September 30, 2024. Samsara stopped providing in-kind services in July 2024.

As of September 30, 2025 and December 31, 2024, the Company recognized $0.1 million in accrued expenses and other current liabilities in the condensed consolidated balance sheets related to the services provided by Samsara under the BSA. As of September 30, 2025 and December 31, 2024, the Company recognized immaterial amounts in accounts payable in the condensed consolidated balance sheets related to the services provided by Samsara under the BSA. The Company recognized a $32.1 million royalty obligation - related party, as a long-term liability, under the Royalty Agreement as of September 30, 2025 and as of December 31, 2024.

The Company issued Samsara convertible promissory notes (Note 8), redeemable convertible preferred stock and common stock. In July 2024, the Company entered into a Royalty Agreement with Samsara (Note 7).

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/1943274/2147480990/946-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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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
-Topic 946
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-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Kalaris Therapeutics, Inc. 10-Q