Fair Value Measurements and Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Financial Instruments Measured on Recurring Basis

The following table sets forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	Fair Value Measurements as of March 31, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Commercial paper ($46,516 included in cash and cash equivalents)	$	129,369	$	—	$	129,369	$	—
U.S. Treasury bills ($26,990 included in cash and cash equivalents)		110,358		110,358		—		—
Money market fund investments (included in cash and cash equivalents)		64,730		64,730		—		—
Corporate debt securities ($2,999 included in cash and cash equivalents)		64,207		—		64,207		—
U.S. government agency bonds ($6,395 included in cash and cash equivalents)		22,159		—		22,159		—
Total fair value of assets	$	390,823	$	175,088	$	215,735	$	—
Liabilities:
MSKCC success payments liability	$	2,484	$	—	$	—	$	2,484
Total fair value of liabilities	$	2,484	$	—	$	—	$	2,484

	Fair Value Measurements as of December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Money market fund investments (included in cash and cash equivalents)	$	181,528	$	181,528	$	—	$	—
Commercial paper ($58,892 included in cash and cash equivalents)		141,676		—		141,676		—
Corporate debt securities		38,649		—		38,649		—
U.S. Treasury bills		26,590		26,590		—		—
U.S. government agency bonds		25,065		—		25,065		—
Total fair value of assets	$	413,508	$	208,118	$	205,390	$	—
Liabilities:
MSKCC success payments liability	$	4,080	$	—	$	—	$	4,080
Total fair value of liabilities	$	4,080	$	—	$	—	$	4,080

Schedule of Fair Value and Amortized Cost of Cash Equivalents and Available-for-Sale Marketable Securities

The fair value and amortized cost of cash equivalents and available-for-sale marketable securities by major security type as of March 31, 2022 and December 31, 2021 are presented in the following tables (in thousands):

	As of March 31, 2022
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Commercial paper ($46,516 included in cash and cash equivalents)	$	129,544	$	3	$	(178	)	$	129,369
U.S. Treasury bills ($26,990 included in cash and cash equivalents)		110,867		1		(510	)		110,358
Money market investments (included in cash equivalents)		64,730		—		—			64,730
Corporate debt securities ($2,999 included in cash and cash equivalents)		64,479		3		(275	)		64,207
U.S. government agency bonds ($6,395 included in cash and cash equivalents)		22,291		—		(132	)		22,159
Total cash equivalents and marketable securities	$	391,911	$	7	$	(1,095	)	$	390,823
Classified as:
Cash and cash equivalents								$	147,630
Marketable securities, short-term									206,101
Marketable securities, long-term									37,092
Total cash equivalents and marketable securities								$	390,823

	As of December 31, 2021
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Money market investments (included in cash equivalents)	$	181,528	$	-	$	—		$	181,528
Commercial paper ($58,892 included in cash equivalents)		141,726		1		(51	)		141,676
U.S. government agency bonds		25,102		-		(37	)		25,065
Corporate debt securities		38,661		4		(16	)		38,649
U.S. Treasury bills		26,626		1		(37	)		26,590
Total cash equivalents and marketable securities	$	413,643	$	6	$	(141	)	$	413,508
Classified as:
Cash and cash equivalents								$	240,420
Marketable securities, short-term									135,412
Marketable securities, long-term									37,676
Total cash equivalents and marketable securities								$	413,508

Schedule of Change in Fair Value of Financial Liability

The following table sets forth a summary of the changes in the fair value of our Level 3 financial liability (in thousands):

	MSKCC Success Payments Liability
Balance at December 31, 2021	$	4,080
Change in fair value		(1,596	)
Balance at March 31, 2022	$	2,484

Schedule of Assumptions Used in Valuation of MSKCC Success Payments Liability

	As of March 31, 2022			As of December 31, 2021
Fair value of common stock	$	9.180		$	15.090
Risk-free interest rate		2.32	%		1.52	%
Expected volatility		75	%		75	%
Probability	4.2% to 14.2%			7.0% to 20.9%
Expected term (years)	4.6 to 6.0			4.2 to 5.5