Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Common Stock Reserved for Future Issuance

As of December 31, 2023, shares of common stock reserved for future issuance are as follows (in thousands):

Stock options, RSUs and PSUs outstanding	27,246
Shares available for future grant under the 2017 Performance Incentive Plan	10,101
Shares available for issuance under the employee stock purchase plan	775
Total common stock reserved for issuance	38,122

Schedule of Stock-Based Compensation Expense

We recognize total stock-based compensation expense in our Consolidated Statements of Operations as follows (in thousands):

	Year Ended December 31,
	2023		2022		2021
Cost of goods sold	$	3,177	$	2,824	$	2,779
Research and development		13,890		27,727		54,821
General and administrative		16,321		24,488		37,074
Restructuring, impairment and costs of terminated program		—		2,281		—
Total stock-based compensation	$	33,388	$	57,320	$	94,674

Schedule of Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:

	Year Ended December 31,
	2023			2022			2021
Average risk-free interest rate		4.0	%		2.9	%		1.2	%
Dividend yield		0.0	%		0.0	%		0.0	%
Average volatility factor		88.4	%		77.9	%		63.8	%
Weighted-average expected life	5.1 years			5.6 years			5.5 years
Weighted-average grant-date fair value of options granted	$	0.37		$	3.18		$	8.07

Schedule of Stock Option Activity Under Equity Incentive Plans

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for price per share and contractual life information):

						Weighted-
				Weighted-		Average
				Average		Remaining
	Number			Exercise		Contractual		Aggregate
	of			Price		Life		Intrinsic
	Shares			per Share		(in Years)		Value(1)
Outstanding at December 31, 2022		14,088		$	16.40
Options granted		11,854			0.51
Options exercised		—			—
Options forfeited & canceled		(2,926	)		16.07
Outstanding at December 31, 2023		23,016		$	8.26		6.42	$	—
Exercisable at December 31, 2023		6,425			22.99		3.68	$	—

(1)Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2023.

Schedule of Restricted Stock Unit Award Activity

A summary of RSU award activity is as follows (in thousands except for per share amounts):

				Weighted-
				Average
				Grant
				Date Fair
	Units Issued			Value
Unvested at December 31, 2022		9,312		$	6.81
Granted		126			1.10
Vested and released		(2,759	)		7.93
Forfeited and canceled		(2,449	)		6.11
Unvested at December 31, 2023		4,230		$	6.14