Equity (Tables)

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Summary of Stock-based Compensation Expense

Stock-based compensation expense is classified in the condensed consolidated statement of operations as follows:

	Three Months Ended March 31,
(in thousands)	2021		2020
Research and development expenses	$	1,018	$	283
General and administrative expenses	1,402		401
Total stock-based compensation expense	$	2,420	$	683

Schedule of Weighted Average Assumptions

The fair values of stock options granted are estimated using the Black-Scholes option pricing model with the following weighted average assumptions:

	Three Months Ended March 31,
	2021		2020
Expected volatility	89.68	%	90.00	%
Expected dividends	0	%	0	%
Expected terms (years)	6.06		6.05
Risk free rate	0.61	%	0.78	%

Schedule of Stock Options Activity

A summary of the Company’s stock option activity and related information for the three months ended March 31, 2021 is as follows:

	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Life  (in Years)	Aggregate Intrinsic Value (in Thousands)
Outstanding at December 31, 2020	6,846,289	$	6.42	8.71	$	53,127
Options granted	140,800	$	12.83
Options exercised	(91,737)	$	3.07
Options cancelled/forfeited	(3,774)	$	16.63
Outstanding at March 31, 2021	6,891,578	$	6.59	8.51	$	40,710
Exercisable as of March 31, 2021	2,205,214	$	5.04	7.68	$	16,908

Summary of RSU Activity

A summary of the Company’s restricted stock unit activity and related information for the three months ended March 31, 2021 is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value
Non-vested at December 31, 2020	186,500	$	8.19
Restricted stock units granted	—	$	—
Restricted stock units vested	(38,000)	$	5.42
Restricted stock units forfeited	—	$	—
Non-vested at March 31, 2021	148,500	$	8.89