Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

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, 2021, 2020 and 2019 consisted of the following:

	Year Ended December 31,
(in thousands)	2021		2020		2019
United States	$	(89,865)	$	(62,539)	$	(52,314)
Foreign (Austria)	1,186		556		(493)
	$	(88,679)	$	(61,983)	$	(52,807)

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,
	2021		2020		2019
U.S. federal statutory income tax rate	(21.0)	%	(21.0)	%	(21.0)	%
State income taxes, net of federal benefit	(5.4)		(5.9)		(5.8)
Foreign rate differential	—		—		(0.1)
Research and development tax credits	(0.9)		(1.1)		(1.1)
Change in fair value of preferred stock warrant liability	—		—		0.1
Other permanent differences	3.7		0.9		1.4
Change in deferred tax asset valuation allowance	23.7		27.2		26.8
Other	(0.1)		0.1		(0.3)
Effective income tax rate	—	%	0.2	%	—	%

Schedule of Deferred Tax Assets and Liabilities

Net deferred tax assets as of December 31, 2021 and 2020 consisted of the following:

	December 31,
(in thousands)	2021		2020
Net operating loss carryforwards	$	101,863	$	83,671
Research and development tax credit carryforwards	5,444		4,616
Capitalized research and development expenses	1,760		2,193
Lease liabilities	1,243		1,440
Other	3,372		2,452
Total deferred tax assets	113,682		94,372
Valuation allowance	(111,835)		(92,197)
Deferred tax assets, net of valuation allowance	$	1,847	$	2,175
Right of use assets	1,847		2,175
Total deferred tax liabilities	$	1,847	$	2,175
Total deferred tax assets, net	$	—	$	—

Summary of Valuation Allowance

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2021, 2020 and 2019 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)	2021		2020		2019
Valuation allowance, beginning of year	$	(92,197)	$	(73,410)	$	(22,797)
Increases recorded to income tax provision	(19,638)		(18,787)		(14,485)
Acquisition of business	—		—		(36,128)
Valuation allowance, end of year	$	(111,835)	$	(92,197)	$	(73,410)

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, 2021:

(in millions)	Reserve for Uncertain Tax Position
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
Settlement of unrecognized tax benefit	(0.1)
Balance as of December 31, 2021	$	0.2