Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Schedule of Estimated Fair Value of Options Valuation Assumptions

The fair value of options at date of grant was estimated using the Black-Scholes option-pricing model with the following assumptions:

	Three Months Ended March 31,
	2021		2022
Risk-free interest rate	0.50% - 0.72%		1.67% - 1.90%
Expected dividend yield	0%		0%
Expected life	5.5-6.7 years		5.6-6.7 years
Expected volatility	72%-74%		70%-72%
Weighted-average grant date fair value	$	4.36	$	2.93

Summary of Information about Stock Option Activity

The following table summarizes information about stock option activity during the three months ended March 31, 2022 (in thousands, except share and per share data):

	NUMBER OF SHARES			WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM		AGGREGATE INTRINSIC VALUE
Outstanding, December 31, 2021		2,662,752		$	6.28
Granted		795,119			4.61
Exercised		(4,781	)		4.42
Forfeited		(10,938	)		8.32
Outstanding, March 31, 2022		3,442,152		$	5.89		7.83	$	2,389
Vested and exercisable, March 31, 2022		1,582,865		$	6.18		6.33	$	1,356
Vested and expected to vest, March 31, 2022		2,777,959		$	5.95		7.52	$	1,997

Schedule of RSU Activity

The following table summarizes information about RSU activity during the three months ended March 31, 2022:

	RSUs		AVERAGE GRANT DATE FAIR VALUE (IN DOLLARS PER SHARE)
Outstanding, December 31, 2021		42,250	$	3.25
Granted		—		—
Vested		—		—
Forfeited		—		—
RSUs outstanding at March 31, 2022		42,250	$	3.25

Summary of Stock-Based Compensation Expense

The Company recorded stock-based compensation expense in the following expense categories of its accompanying condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2021 and 2022 (in thousands):

	Three Months Ended March 31,
	2021		2022
Research and development	$	226	$	254
General and administrative		295		382
Total	$	521	$	636