Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Statement of Cash Flows [Abstract]
Net loss	$ (69,705)	$ (92,014)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash operating lease expense	0	354
Depreciation expense	983	689
Share based compensation expense	13,310	13,936
Amortization of discounts on investments, net	(3,368)	(481)
Unrealized foreign currency transaction gain, net	(1,206)	(1,375)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	3,663	4,794
Other receivable	860	(1,244)
Other non-current assets	0	11
Accounts payable	4,949	(1,091)
Accrued expenses	(3,375)	8,197
Other current liabilities	1,186	(248)
Operating lease assets and liabilities, net	(111)	0
Net cash used in operating activities	(52,814)	(68,472)
Cash flows from investing activities:
Purchase of property and equipment	(229)	(1,610)
Purchase of marketable securities	(128,118)	(260,367)
Sales and redemption of marketable securities	206,391	181,780
Net cash provided by (used for) investing activities	78,044	(80,197)
Cash flows from financing activities:
Proceeds from exercise of share options	0	1,710
Net cash provided by financing activities	0	1,710
Effect of exchange rate changes on cash and cash equivalents	(998)	(2,291)
Net increase (decrease) in cash, cash equivalents and restricted cash	24,232	(149,250)
Cash and cash equivalents, and restricted cash—beginning of period	79,294	248,182
Cash and cash equivalents, and restricted cash—end of period	103,526	98,932
Cash and cash equivalents—end of period	103,457	78,862
Restricted cash—end of period	69	20,070
Cash and cash equivalents, and restricted cash—end of period	103,526	98,932
Supplemental disclosure of cash information
Cash paid for income taxes	17	523
Supplemental disclosure of non-cash operating activities:
Purchase of property and equipment in accounts payable	$ 133	$ 551