Subsequent events	9 Months Ended
Sep. 30, 2026
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent events In October 2026, the Company announced achievement of an additional milestone associated with the initiation of a second Phase 2 study initiated by its collaborator Novartis evaluating MRT-6160 (DDY391) in participants with active moderate to severe psoriatic arthritis. The first patient visit of this study triggered a $37.5 million milestone payment to the Company under the 2024 Novartis Agreement.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/855/tableOfContent

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

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