Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax, Domestic and Foreign

Loss before the provision for income taxes for the years ended December 31, 2020, 2019 and 2018 consisted of the following:

	Year Ended December 31,
(in thousands)	2020		2019		2018
United States	$	(62,539)	$	(52,314)	$	(33,285)
Foreign (Austria)	556		(493)		—
	$	(61,983)	$	(52,807)	$	(33,285)

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the U.S. federal statutory income tax rate to the Company's effective income tax rate is as follows:

	Year Ended December 31,
	2020		2019		2018
U.S. federal statutory income tax rate	(21.0)	%	(21.0)	%	(21.0)	%
State income taxes, net of federal benefit	(5.9)		(5.8)		(6.2)
Foreign rate differential	—		(0.1)		—
Research and development tax credits	(1.1)		(1.1)		(3.7)
Change in fair value of preferred stock warrant liability	—		0.1		2.4
Other permanent differences	0.9		1.4		0.9
Change in deferred tax asset valuation allowance	27.2		26.8		27.8
Other	0.1		(0.3)		(0.2)
Effective income tax rate	0.2	%	—	%	—	%

Schedule of Deferred Tax Assets and Liabilities

Net deferred tax assets as of December 31, 2020 and 2019 consisted of the following:

	December 31,
(in thousands)	2020		2019
Net operating loss carryforwards	$	83,671	$	65,487
Research and development tax credit carryforwards	4,616		3,654
Capitalized research and development expenses	2,193		2,626
Lease liabilities	1,440		765
Other	2,452		1,413
Total deferred tax assets	94,372		73,945
Valuation allowance	(92,197)		(73,410)
Deferred tax assets, net of valuation allowance	$	2,175	$	535
Right of use assets	2,175		535
Total deferred tax liabilities	$	2,175	$	535
Total deferred tax assets, net	$	—	$	—

Summary of Valuation Allowance

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2020, 2019 and 2018 related primarily to the increases in net operating loss carryforwards and research and development tax credit carryforwards and were as follows:

	Year Ended December 31,
(in thousands)	2020		2019		2018
Valuation allowance, beginning of year	$	(73,410)	$	(22,797)	$	(13,546)
Increases recorded to income tax provision	(18,787)		(14,485)		(9,251)
Acquisition of business	—		(36,128)		—
Valuation allowance, end of year	$	(92,197)	$	(73,410)	$	(22,797)

Schedule of Unrecognized Tax Benefits Roll Forward

The following table summarizes the Company’s reserve for uncertain tax positions for the three years ended December 31, 2020:

(in millions)	Reserve for Uncertain Tax Position
Balance as of December 31, 2018	$	—
Acquisition of uncertain tax position reserves through Merger	0.2
Balance as of December 31, 2019	0.2
Increase in unrecognized tax benefit for tax positions taken during year	0.1
Balance as of December 31, 2020	$	0.3