Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Measurements

Schedule of assets and liabilities measured and recorded in financial statements at fair value on a recurring basis

	December 31, 2021
(In thousands)	Total		Level 1		Level 2		Level 3
Assets
Cash	$	250	$	250	$	—	$	—
Cash equivalents – money market funds		32,295		32,295		—		—
Total assets	$	32,545	$	32,545	$	—	$	—
	December 31, 2020
(In thousands)	Total		Level 1		Level 2		Level 3
Assets
Cash	$	250	$	250	$	—	$	—
Cash equivalents – money market funds		32,979		32,979		—		—
Short-term investments – commercial paper		3,499		—		3,499		—
Short-term investments – US treasury bills		1,000		—		1,000		—
Total assets	$	37,728	$	33,229	$	4,499	$	—
Liabilities
Warrant liability	$	6,983	$	—	$	—	$	6,983
Future tranche right liability		118,803		—		—		118,803
Total liabilities	$	125,786	$	—	$	—	$	125,786

Schedule of reconciliation measured at fair value on a recurring basis using unobservable inputs

			Future
	Warrant		Tranche Right
(In thousands)	Liability		Liability
Balance, December 31, 2019	$	3,241	$	46,436
Change in the fair value of liability		3,742		72,367
Balance, December 31, 2020	$	6,983	$	118,803
Change in the fair value of liability (1)		(6,983)		(118,803)
Balance, December 31, 2021	$	—	$	—

(1) During the year ended December 31, 2021, the Company’s liability-classified warrants and future tranche rights terminated, and accordingly, the liabilities were derecognized. See Notes 7 and 8.

Warrant liability

Fair Value Measurements

Schedule of assumptions used in determining fair value

	December 31,		December 31,
	2020		2019
Risk-free interest rate		0.50%		1.79%
Expected dividend yield		—		—
Expected term (years)		5.98		6.98
Expected volatility		80%		80%
Exercise price (per share)	$	1.52	$	1.52

Future tranche right liability

Fair Value Measurements

Schedule of assumptions used in determining fair value

	December 31,		December 31,
	2020		2019
Risk-free interest rate		0.64% - 0.73%		1.84% - 1.88%
Expected dividend yield		—		—
Expected term (years) of call options on preferred stock		0.25 - 1.12		1.16 - 2.16
Expected term (years) of warrants		7.25 - 8.12		8.16 - 9.16
Expected volatility		80%		80%
Exercise price (per share) for common stock equivalent for preferred stock and warrant	$	1.52 - 1.82	$	1.52 - 1.82