Cabaletta Bio, Inc. Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

Collaborations, Licensing Agreements and Other Agreements - Additional Information (Details)

Collaborations, Licensing Agreements and Other Agreements - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended				9 Months Ended
	May 31, 2020	Sep. 30, 2026	Sep. 30, 2025	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2026	Sep. 30, 2025	Jun. 30, 2026	Jan. 31, 2024	Dec. 31, 2023	Aug. 31, 2023	May 31, 2023	Oct. 07, 2022
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Research and development expense		$ 47,144	$ 39,824			$ 128,927	$ 106,480
Upfront payment										$ 1,100
License Agreement
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Obligation to be paid		2,000				$ 2,000
Payment term						3 years
License maintenance fee	$ 33					$ 10
Total milestone payments						21,000
Amounts due to agreement		0				0
License Agreement \| Maximum
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Total milestone payments						12,000
Sponsored Research Agreements
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Obligation to be paid		12,560				12,560
Master Translational Research Services Agreement
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Research and development expense		$ 61	$ 894			990	$ 4,188
Remaining research and development expense to be incurred						0
Oxford Biomedica
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Obligation to be paid											$ 5,000
Total milestone payments						500
Research and development expense						26,000
Upfront payment												$ 500
Expenses						18,868
Nanjing IASO Biotherapeutics Co., Ltd.
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Total milestone payments				$ 1,500	$ 1,000	2,500
Upfront payment								$ 162,000					$ 2,500
Autolus Holdings
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Upfront payment					$ 1,200				$ 100
Autolus Holdings \| Maximum
Collaborations, Licensing Agreements And Other Agreements [Line Items]
Total milestone payments						$ 15,000