Stock Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Stock Options Valuation Assumptions Using a Black-Scholes Option Pricing Model

The assumptions used in the Black-Scholes option pricing model are as follows:

	For the Year Ended December 31,
	2022	2021
Expected volatility	68.7% - 70.1%	64.6% - 71.7%
Weighted-average risk-free interest rate	1.46% - 4.16%	0.50% - 1.33%
Expected dividend yield	— %	— %
Expected term (in years)	5.5 - 6.25	5.5 - 6.25
Underlying common stock fair value	$1.40 - $4.17	$4.85 - $13.91

Summary of Option Activity under Plans

A summary of option activity under the Plans during the year ended December 31, 2022 is as follows:

	Number of Options			Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
								(in thousands)
Outstanding at January 1, 2022		7,624,306		$	14.25		7.5	$	2,069
Granted		3,089,655		$	2.64
Exercised		(293	)	$	2.71
Cancelled/Forfeited		(847,934	)	$	10.25
Outstanding at December 31, 2022		9,865,734		$	10.96		7.2	$	493
Vested and expected to vest at    December 31, 2022		9,865,734		$	10.96		7.2	$	493
Exercisable at December 31, 2022		6,111,596		$	13.19		6.3	$	493

Summary of Company's RSU Activity

The following table summarizes the Company's RSU activity for the year ended December 31, 2022:

	Number of			Weighted-
	Restricted			Average Grant
	Stock Units			Date Fair Value
Outstanding at January 1, 2022		307,600		$	12.75
Granted		400,495		$	2.70
Vested		(106,890	)	$	12.42
Forfeited		(58,026	)	$	6.05
Outstanding at December 31, 2022		543,179		$	6.12

Schedule of Stock-Based Compensation Expense

The Company recorded stock-based compensation expense related to stock options, shares purchased under the 2018 ESPP and restricted stock units as follows:

	For the Year Ended December 31,
	2022		2021
	(in thousands)
General and administrative	$	7,867	$	8,450
Research and development		5,187		8,795
	$	13,054	$	17,245