Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock-Based Compensation Cost that has been Included in Statements of Operations and Comprehensive Loss

The stock-based compensation cost that has been included in the statements of operations and comprehensive loss is shown as below (in thousands):

	Three months ended June 30,				Six months ended June 30,
	2024		2023		2024		2023
Cost of product revenues	$	4	$	5	$	8	$	9
Research and development		164		301		376		593
Selling, general and administrative		266		353		559		659
Total stock-based compensation	$	434	$	659	$	943	$	1,261

Summary of Assumptions Used to Estimate Fair Value of Options Granted and Shares Purchased

The Company used the following assumptions to estimate the fair value of stock options granted and shares purchased under its employee stock purchase plan for the three and six months ended June 30, 2024 and 2023. There were no stock options granted to employees for the three and six months ended June 30, 2024.

	Three months ended June 30,					Six months ended June 30,
	2024		2023			2024		2023
Stock Options
Risk-free rate		—		3.96	%		—	3.96-4.07%
Expected dividend yield		—		—			—		—
Expected life of option (in years)		—		7.3			—	7.0-7.5
Volatility		—		88	%		—	87-88%

	Three months ended June 30,						Six months ended June 30,
	2024			2023			2024			2023
Employee Stock Purchase Plan
Risk-free rate		5.43	%		5.14	%	5.43-5.50%			4.58-5.14%
Expected dividend yield		—			—			—			—
Expected life of option (in years)	0.5			0.5			0.5			0.5
Volatility		246	%		88	%		246	%	88-104%