Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Components of Net Loss Before Income Taxes

The components of net loss before income taxes for the years ended December 31, 2022 and 2021 are as follows (in thousands):

	December 31,
	2022			2021
U.K.	$	(156,000	)	$	(147,337	)
Non-U.K.		2,966			3,581
Net loss before taxes	$	(153,034	)	$	(143,756	)

Schedule of Provision for (Benefit from) Income Taxes

The provision for (benefit from) income taxes for the years ended December 31, 2022 and 2021 are as follows (in thousands):

	December 31,
	2022			2021
Current (benefit) provision
Federal—United States	$	618		$	(1,025	)
State—United States		144			334
Other foreign		147			388
United Kingdom		—			—
Total current (benefit) provision		909			(303	)
Deferred provision (benefit)
Federal—United States		(3,066	)		1,099
State—United States		(204	)		(312	)
United Kingdom		(13	)		—
Other foreign		—			344
Total deferred provision (benefit)		(3,283	)		1,131
Total provision (benefit) for income taxes	$	(2,374	)	$	828

Schedule of Reconciliation of Income Tax Expense (Benefit)

The following table presents a reconciliation of income tax expense (benefit) computed at the UK statutory income tax rate to the effective income tax rate as reflected in the consolidated financial statements (in thousands):

	December 31,
	2022			2021
Income taxes at United Kingdom statutory rate	$	(29,072	)	$	(27,313	)
Change in valuation allowance		34,333			59,691
Reduction in research expense for credits granted		1,805			6,674
Change in tax rates		(8,240	)		(38,785	)
Tax credits		(2,049	)		(2,232	)
U.S. Deduction for foreign derived intangible income		(1,489	)		(196	)
Permanent differences, including share-based compensation deduction shortfalls		2,387			2,863
U.S. state income taxes		(45	)		17
Foreign rate differential		(4	)		109
Total provision (benefit) for income taxes	$	(2,374	)	$	828

Schedule of Deferred Tax Assets and Liabilities

The following table presents the principal components of the Company’s deferred tax assets and liabilities as of December 31, 2022 and 2021 (in thousands):

	December 31,
	2022			2021
Deferred tax assets
Net operating loss carryforwards	$	158,344		$	126,563
Amortization		11,215			25,206
Research and development credits		2,525			2,449
Capitalized research and development costs		2,285			—
Share-based compensation		9,282			9,353
Accruals		946			798
Lease liability		6,126			6,444
Property and equipment		—			1,022
Total deferred tax assets		190,723			171,835
Valuation allowance		(177,630	)		(161,573	)
Fixed assets and right-of-use asset		(5,724	)		(6,176	)
Other non-current assets (net deferred tax assets and liabilities)	$	7,369		$	4,086

Schedule of Changes in Valuation Allowance for Deferred Tax Assets Related Primarily to Increase in U.K. Net Operating Loss Carryforwards

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2022 and 2021 related primarily to the increase in UK net operating loss carryforwards as follows (in thousands):

	December 31,
	2022			2021
Valuation allowance as of beginning of year	$	(161,573	)	$	(103,890	)
Increases recorded to income tax provision		(34,248	)		(59,691	)
Effect of foreign currency translation		18,191			2,008
Valuation allowance as of end of year	$	(177,630	)	$	(161,573	)