Annual report pursuant to Section 13 and 15(d)

Stock-Based Payments (Tables)

Stock-Based Payments (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

A summary of the status of stock options as of December 31, 2021 and December 31, 2020 and changes during the year ended December 31, 2021 is presented below:

								Aggregate
				Weighted		Remaining		Intrinsic
				Average		Contractual		Value
	Shares			Exercise Price		Life (in years)		(in thousands)
Outstanding at December 31, 2020		5,468,605		$	8.90	7.2		$	13,124
Granted		2,417,600			7.69
Exercised		(20,134	)		7.77
Cancelled		(1,208,803	)		10.00
Outstanding at December 31, 2021		6,657,268		$	8.27		7.2	$	494
Exercisable at December 31, 2021		3,736,652		$	8.86		5.8	$	494

Summary of Status of Restricted Stock Units

A summary of the status of restricted stock units as of December 31, 2020 and December 31, 2021 and changes during the year ended December 31, 2021 is presented below:

				Weighted
				Average Grant
	Shares			Date Fair Value
Outstanding at December 31, 2020		1,734,383		$	7.40
Granted		1,747,554			6.31
Vested		(286,837	)		7.70
Forfeited		(507,613	)		8.15
Outstanding at December 31, 2021		2,687,487		$	6.52

Schedule of Weighted-Average Assumptions used in Black-Scholes Option-Pricing Model

The fair value of each stock option granted was estimated on the date of grant using the Black-Scholes option-pricing model based on the following weighted-average assumptions:

	Year Ended December 31,
	2021			2020			2019
Weighted-average risk-free interest rate		0.99	%		1.28	%		2.42	%
Expected dividend yield		—	%		—	%		—	%
Expected option term (in years)		6.03			5.99			6.00
Volatility		81.56	%		78.27	%		91.35	%

Summary of Stock-based Compensation Expense for Stock Options and Restricted Stock Units

The following table summarizes the stock-based compensation expense for stock options, restricted stock units and restricted common stock granted to employees and non-employees and from the 2016 ESPP recorded in the Company’s statements of operations:

	Year Ended December 31,
	2021		2020		2019
Research and development	$	5,706	$	4,732	$	3,472
General and administrative		4,648		6,207		6,367
Total stock-based compensation expense	$	10,354	$	10,939	$	9,839