Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 68,424	$ 55,912
Marketable securities	75,326	164,195
Accounts receivable	8,467	1,480
Prepaid expenses and other current assets	9,986	23,011
Research and development tax credit receivable	5,942	30,723
Total current assets	168,145	275,321
Non-current assets:
Operating lease right-of-use-assets	22,774	24,316
Property and equipment, net	8,138	4,767
Restricted cash	4,215	4,266
Intangible assets, net	3,560	4,149
Other assets	12,075	9,590
Total non-current assets	50,762	47,088
Total assets	218,907	322,409
Current liabilities:
Accounts payable	9,318	10,008
Accrued expenses and other current liabilities	34,437	24,318
Deferred revenue	959	346
Operating lease liabilities	6,424	7,335
Notes payable, current	9,429	786
Total current liabilities	60,567	42,793
Notes payable, long-term	22,991	32,086
Deferred revenue, net of current portion	10,315	12,519
Operating lease liabilities, net of current portion	19,246	19,278
Other long-term liabilities	7,524	5,783
Total liabilities	120,643	112,459
Commitments and contingencies (Note 17)
Shareholders’ equity:
Ordinary shares, GBP0.10 par value, authority to allot up to a maximum nominal value of GBP13,023,851.50 of shares at December 31, 2022 and 2021, respectively; Issued and outstanding - 126,947,225 and 125,674,095 shares at December 31, 2022 and 2021, respectively	16,419	16,253
Additional paid-in capital	956,711	940,675
Accumulated other comprehensive income	26,018	3,246
Accumulated deficit	(900,884)	(750,224)
Total shareholders’ equity	98,264	209,950
Total liabilities and shareholders’ equity	$ 218,907	$ 322,409