Reorganization and Reverse Stock Split (Tables)

12 Months Ended

Dec. 31, 2021

Reorganization And Reverse Stock Split [Abstract]

Number of Shares of Common Stock Exchanged and Issued to Unitholders on Split Adjusted Basis

the existing units of the LLC were cancelled and the number of shares of common stock exchanged and issued to the LLC’s unitholders in the Reorganization is shown in the below table by unit class, on a split adjusted basis:

Cullinan Oncology, LLC Unit Type	Number of Management's Shares Issued		Adjusted for the Reverse Stock Split
Series C Preferred Units		66,599,045		9,461,414
Series B Preferred Units		63,141,016		8,970,154
Series A1 Preferred Units		50,000,000		7,103,280
Series Seed Preferred Units		16,000,000		2,273,050
Non-Voting Incentive Units		11,896,500		1,689,949
Common Units		34,747,722		4,936,415
Total shares issued		242,384,283		34,434,262

Summary of LLC Units Previously Reported as Redeemable Preferred Units or Temporary Equity Converted Reclassified to Equity

All LLC units that were previously reported as Redeemable Preferred Units, or temporary equity, were converted to common stock of the Company upon the execution of the Reorganization and have been reclassified to stockholders’ equity for all periods presented, as if the Reorganization occurred at the beginning of the earliest period presented in the Company’s financial statements for the years ended December 31, 2020 and 2019:

	As of December 31, 2020
	As Reported			Adjustment			As Adjusted
	(in thousands)
Redeemable Preferred Units
Series Seed Redeemable Preferred Units	$	3,956		$	(3,956	)	$	—
Series A1 Redeemable Preferred Units		49,946			(49,946	)		—
Series B Redeemable Preferred Units		97,909			(97,909	)		—
Series C Redeemable Preferred Units		124,841			(124,841	)		—
Total Redeemable Preferred Units		276,652			(276,652	)		—
Stockholders' Equity (Members' Deficit)
Non-Voting Incentive Units	1				(1	)		—
Common Stock		—			3			3
Additional paid-in capital		15,698			276,650			292,348
Accumulated other comprehensive loss		(2	)		—			(2	)
Accumulated deficit		(93,339	)		—			(93,339	)
Total Cullinan Stockholders' Equity (Members' Deficit)		(77,642	)		276,652			199,010
Non-controlling interests in subsidiaries		1,304			—			1,304
Total Stockholders' Equity (Members' Deficit)	$	(76,338	)	$	276,652		$	200,314

	As of December 31, 2019
	As Reported			Adjustment			As Adjusted
	(in thousands)
Redeemable Preferred Units
Series Seed Redeemable Preferred Units	$	3,956		$	(3,956	)	$	—
Series A1 Redeemable Preferred Units		49,946			(49,946	)		—
Series B Redeemable Preferred Units		83,872			(83,872	)		—
Series C Redeemable Preferred Units		—			—			—
Total Redeemable Preferred Units		137,774			(137,774	)		—
Stockholders' Equity (Members' Deficit)
Non-Voting Incentive Units	1				(1	)		—
Common Stock		—			2			2
Additional paid-in capital	770				137,773			138,543
Accumulated other comprehensive loss		(4	)		—			(4	)
Accumulated deficit		(41,540	)		—			(41,540	)
Total Cullinan Stockholders' Equity (Members' Deficit)		(40,773	)		137,774			97,001
Non-controlling interests in subsidiaries	864				—			864
Total Stockholders' Equity (Members' Deficit)	$	(39,909	)	$	137,774		$	97,865