Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Payments (Tables)

Stock-Based Payments (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

A summary of the status of stock options as of December 31, 2022 and September 30, 2023 and changes during the nine months ended September 30, 2023 is presented below:


								Aggregate
				Weighted		Remaining		Intrinsic
				Average		Contractual		Value
	Shares			Exercise Price		Life (in years)		(in thousands)
Outstanding at December 31, 2022		1,727,237		$	39.94		5.7	$	—
Granted		54,000			3.70
Cancelled		(35,060	)
Outstanding at September 30, 2023		1,746,177		$	38.22		5.2	$	13,880
Exercisable at September 30, 2023		1,155,463		$	49.51		3.2	$	380

Summary of Status of Restricted Stock Units

A summary of the status of restricted stock units and restricted stock awards as of December 31, 2022 and September 30, 2023 and changes during the nine months ended September 30, 2023 is presented below:


	Shares
	Subject to
	Restricted Stock
	Units and			Weighted
	Restricted Stock			Average Grant
	Awards			Date Fair Value
Outstanding at December 31, 2022		1,204,421		$	14.68
Granted		1,462,636			3.99
Vested		(84,418	)		32.02
Forfeited		(116,748	)		17.17
Outstanding at September 30, 2023		2,465,891		$	7.54

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

The fair value of each stock option granted during the nine months ended September 30, 2023 and the three and nine months ended September 30, 2022 was estimated on the date of grant using the Black-Scholes option-pricing model based on the following weighted-average assumptions:


	Three Months Ended September 30,			Nine Months Ended September 30,
	2022			2023			2022
Weighted-average risk-free interest rate		3.60	%		3.93	%		2.85	%
Expected option term (in years)		5.79			5.32			5.88
Volatility		83.27	%		84.44	%		82.18	%

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 condensed consolidated statements of operations:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development	$	1,586	$	1,496	$	4,236	$	4,324
General and administrative		1,501		1,459		4,310		4,183
Restructuring		168		—		168		—
Total stock-based compensation expense	$	3,255	$	2,955	$	8,714	$	8,507