Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

The following table shows the stock option activity, as follows:

	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)
Outstanding as of January 1, 2019		49,798		$	233.45		8.1	$	—
Granted		42,244			28.87
Exercised		—			—
Forfeited / Canceled		(639	)		79.38
Outstanding as of December 31, 2019		91,403			139.96		8.2		—
Granted		2,191,462			9.15
Options assumed in connection with acquisition		1,346,398			7.58
Exercised		—			—
Forfeited / Canceled		(7,784	)		586.16
Outstanding as of December 31, 2020		3,621,479		$	10.63		8.9	$	23,938,701
Options vested and expected to vest as of December 31, 2020		3,621,479		$	15.21		8.9	$	23,938,701
Options exercisable as of December 31, 2020		878,033		$	16.00		8.2	$	6,297,510

Summary of PRSU Activity

The following table shows the PRSU activity, as follows:

	Shares Issuable Under PRSUs			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)
Outstanding as of January 1, 2019		4,358		$	86.94		9.2	$	—
Granted		3,056			66.96
PRSUs Vested		(4,358	)		86.94
Forfeited / Canceled		—			—
Outstanding as of December 31, 2019		3,056			66.96		9.2		—
Granted		—			—
PRSUs Vested		(3,056	)		66.96
Forfeited / Canceled		—			—
Outstanding as of December 31, 2020		—		$	—			$	—
PRSUs vested and expected to vest as of December 31, 2020		—		$	—			$	—
Options exercisable as of December 31, 2020		—		$	—			$	—

Schedule of Stock-Based Compensation Expense Related to Stock-Based Awards

Total compensation expense related to all of the Company’s stock-based awards for the years ended December 31, 2020 and 2019 was comprised of the following (in thousands):

	Year Ended December 31,
	2020		2019
Stock-based compensation classified as:
Research and development expense	$	1,254	$	343
General and administrative expense		1,917		965
Total stock-based compensation expense	$	3,171	$	1,308

Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Determine the Fair Value of Stock Options Granted

The following table presents the assumptions used in the Black-Scholes option pricing model to determine the fair value of stock options granted in the periods presented, as follows:

	Year Ended December 31,
	2020	2019
Expected stock price volatility	77% - 107%	74% - 87%
Risk-free interest rate	0% - 1%	1% - 3%
Expected life of option (in years)	4 - 6	6
Estimated dividend yield	0%	0%