Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Summary of Calculation of Basic and Diluted Net Loss Per Share

	Year ended December 31,
	2022		2021
	(in thousands, except per share data)
Numerator:
Net income (loss) attributable to common stockholders of Cullinan	$	111,214	$	(65,570	)
Denominator:
Weighted-average common stock outstanding - basic		45,164		43,077
Dilutive effect of common stock issuable from assumed exercise of equity awards		1,476		—
Weighted-average common stock outstanding - diluted		46,640		43,077
Earnings (net loss) per share:
Basic	$	2.46	$	(1.52	)
Diluted	$	2.38	$	(1.52	)

The Company used the treasury stock method to determine the number of dilutive shares. The following table sets forth potential common shares that were excluded from the computation of the diluted earnings (net loss) per share for 2022 and 2021 because their effect would have been anti-dilutive:

Summary of Equity Instruments Excluded from Computation of Diluted Net Loss Per Share

	Year ended December 31,
	2022		2021
Stock options		6,842		9,259
RSAs		—		89
RSUs		25		—
ESPP		7		—
Total		6,874		9,348