Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Provision for Income Taxes

The provision for income taxes differs from the amount expected by applying the federal statutory rate to the loss before taxes as follows:

	Year Ended December 31,
	2020			2019			2018
Federal statutory income tax rate		21.0	%		21.0	%		21.0	%
State income taxes		(1.9	%)		7.0	%		6.9	%
Change in valuation allowance		(21.5	%)		(31.4	%)		(29.4	%)
Research tax credits		2.7	%		3.6	%		2.7	%
Other permanent differences		(0.3	%)		(0.4	%)		(1.3	%)
Change in fair value of redeemable convertible preferred stock liability		0.0	%		0.2	%		0.1	%
Provision for income taxes		0.0	%		0.0	%		0.0	%

Schedule of Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets

The tax effects of temporary differences and carryforwards of the deferred tax assets are presented below (in thousands):

	As of December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	13,418		$	23,947
Research and development credit carryforwards		3,813			2,995
Lease liability		1,420			1,895
Intangible assets		1,274			1,809
Stock-based compensation		705			407
Accruals and reserves		505			436
Deferred revenue		17,332			—
Gross deferred tax assets		38,467			31,489
Less: Valuation allowance		(36,879	)		(29,462	)
Deferred tax assets, net of valuation allowance		1,588			2,027
Deferred tax liabilities:
Right-of-use assets		(1,100	)		(1,415	)
Property and equipment		(488	)		(612	)
Net deferred tax assets	$	—		$	—

Summary of Activity Related to Company’s Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands).

Balance as of January 1, 2019	$	399
Increase related to prior year tax positions		59
Increase related to current year tax positions		288
Balance as of December 31, 2019	$	746
Increase related to prior year tax positions		2
Increase related to current year tax positions		153
Balance as of December 31, 2020	$	901