Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Net Deferred Tax Assets

Significant components of the Company’s net deferred income tax assets consist of the following (in thousands):

	December 31,
	2019			2018			2017
Deferred tax asset (liability)
Net operating loss carryforwards	$	46,305		$	41,152		$	27,999
Non-deductible accrued expenses		422			245			248
Right of use asset		(138	)		—			—
Lease liability		264			—			—
Deferred rent		—			148			49
Deferred revenue		—			—			38
Stock compensation expense		1,472			899			387
Depreciation differences		(94	)		(125	)		(18	)
Federal tax credits		7,249			6,481			3,437
State tax credits		623			757			524
Disallowed interest expense		99			—			—
Charitable contributions		4			6			6
Valuation allowance		(56,206	)		(49,563	)		(32,670	)
Net deferred tax asset	$	—		$	—		$	—

Schedule of Statutory and Effective Income Tax Rate Reconciliation

A reconciliation of the statutory tax rates and the effective tax rates is as follows:

	Year Ended December 31,
	2019			2018			2017
U.S. federal tax rate		21.00	%		21.00	%		34.00	%
State tax rate		—			(0.73	)		2.42
Permanent difference and other		(1.33	)		(0.33	)		(2.84	)
Tax credit		2.06			3.96			3.97
Valuation allowance		(21.73	)		(20.39	)		(12.42	)
ASC 740-10		—			(3.51	)		—
Impact of federal rate change		—			—			(25.13	)
		0.00	%		0.00	%		0.00	%