Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Summary of Available-for-Sale Securities

Cash equivalents and investments, all of which are classified as available-for-sale securities, and restricted cash consisted of the following (in thousands):

	December 31, 2021								December 31, 2020
	Cost		Unrealized Gain		Unrealized (Loss)		Estimated Fair Value		Cost		Unrealized Gain		Unrealized (Loss)		Estimated Fair Value
Money market funds	$	56,337	$	—	$	—	$	56,337	$	106,782	$	—	$	—	$	106,782
Corporate notes and commercial paper		—		—		—		—		6,501		1		—		6,502
U.S. government agency securities		—		—		—		—		1,501		2		—		1,503
	$	56,337	$	—	$	—	$	56,337	$	114,784	$	3	$	—	$	114,787
Classified as:
Cash equivalents							$	56,067							$	106,342
Short-term investments								—								8,005
Restricted cash								270								440
Total cash equivalents,    restricted cash and    investments							$	56,337							$	114,787

Schedule of Property and Equipment Net

Property and equipment, net consist of the following (in thousands):

	December 31,
	2021			2020
Research and development equipment	$	1,882		$	2,174
Furniture and office equipment		167			167
Computer equipment		487			448
Software		80			80
Leasehold improvements		1,234			1,234
Total property and equipment		3,850			4,103
Less: accumulated depreciation		(3,294	)		(3,413	)
Property and equipment, net	$	556		$	690

Summary of Accrued and Other Liabilities

Accrued and other liabilities consist of the following (in thousands):

	December 31,
	2021		2020
Accrued clinical and manufacturing expenses	$	5,086	$	7,910
Accrued payroll and related expenses		3,283		5,142
Current portion of lease liability		1,374		1,903
Other		613		1,452
Total accrued and other liabilities	$	10,356	$	16,407