Equity Incentive Plan (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Stock-based Compensation Expense for Equity Incentive Plans

The stock-based compensation expense for the Company’s equity incentive plans was allocated as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Cost of products sold	$	134	$	208	$	390	$	260
Research and development		586		291		1,097		421
Selling, general and administrative		1,016		446		1,937		792
Total	$	1,736	$	945	$	3,424	$	1,473

Stock-based compensation expense excludes amounts capitalized to inventory. During the three and six months ended June 30, 2022, the Company capitalized stock-based compensation expense of $0.5 million and $0.9 million to inventory, respectively, and during the three and six months ended June 30, 2021, the Company capitalized $0.2 million and $0.3 million of stock-based compensation expense to inventory, respectively.

Total stock-based compensation expense by type of award was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Stock options	$	386	$	528	$	725	$	964
Restricted stock units		1,620		334		3,057	$	375
Employee Stock Purchase Plan		77		83		166	$	134
Total	$	2,083	$	945	$	3,948	$	1,473

Summary of Stock Option Activity

A summary of stock option activity for the six months ended June 30, 2022 is as follows:

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Balance as of December 31, 2021		3,712,274		$	3.30		8.1	$	23,150
Granted		416,213		$	1.85		—		—
Exercised		(60,494	)	$	1.42		—		—
Cancelled		(119,422	)	$	7.39		—		—
Balance as of June 30, 2022		3,948,571		$	3.05		7.2	$	1,542
Options vested and expected to vest as of June 30, 2022		3,948,571		$	3.05		7.2	$	1,542
Options vested and exercisable as of June 30, 2022		1,928,654		$	2.40		6.8	$	1,132

Summary of Assumptions Used to Estimate Fair Value of Warrants

The Company determined the fair value of the Warrants as of February 4, 2022 using the Black-Scholes option pricing model and applying the following assumptions:

Fair value of common stock	$	5.15
Expected term (in years)		7.0
Risk-free interest rate		1.9	%
Dividend yield		—
Volatility		92.6	%

The weighted-average grant date fair value of the options granted during the six months ended June 30, 2022 and 2021 was $1.25 and $7.52 per share, respectively, as calculated using the Black-Scholes option-pricing model with the following assumptions on a weighted-average basis:

	Six Months Ended June 30,
	2022			2021
Fair value of common stock	$	1.85		$	17.00
Expected term (in years)		5.5			6.0
Risk-free interest rate		3.0	%		0.6	%
Dividend yield		—			—
Volatility		79.5	%		46.9	%

Summary of Restricted Stock Units Activity

The Company had the following activity for RSUs for the six months ended June 30, 2022:

	Underlying Shares			Weighted- Average Grant Date Fair Value
Balance as of December 31, 2021		3,387,505		$	7.57
Granted		574,414		$	3.94
Vested		(279,514	)	$	6.59
Canceled or forfeited		(314,305	)	$	7.84
Balance as of June 30, 2022		3,368,100		$	7.00

Summary of Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plans

The fair value of shares to be issued under the Company’s ESPP was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions on a weighted-average basis for the six months ended June 30, 2022 and 2021:

	Six Months Ended June 30,
	2022			2021
Fair value of common stock	$	4.54		$	17.00
Expected term (in years)		0.5			0.5
Risk-free interest rate		0.1	%		0.6	%
Dividend yield		—			—
Volatility		90.5	%		46.9	%