CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (41,183)	$ (43,863)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	86	466
Non-cash lease expense	461	380
(Accretion) amortization of short-term investment (discounts) premiums	(729)	76
Stock-based compensation expense	10,029	10,467
Changes in operating assets and liabilities:
Interest receivable	(87)	(122)
Prepaid expenses and other current assets and prepaid expenses to related party	(333)	284
Other assets	122	122
Income tax payable	2	(500)
Accounts payable, accrued expenses and amount due to related party	(486)	(13,786)
Net cash used in operating activities	(32,118)	(46,476)
Cash flows from investing activities
Purchase of short-term investments	(11,756)	(60,979)
Maturities of short-term investments	53,480	6,000
Net cash provided by (used in) investing activities	41,724	(54,979)
Net increase (decrease) in cash, cash equivalents, and restricted cash	9,606	(101,455)
Cash, cash equivalents, and restricted cash at beginning of period	106,944	202,513
Cash, cash equivalents, and restricted cash at end of period	116,550	101,058
Non-cash investing and financing activities
Unrealized gain (loss) on available-for-sale securities	167	(195)
Reduction of right-of-use asset and operating lease liability due to modification and remeasurement		(5,506)
Supplemental disclosure of cash flows
Income taxes paid, net of refunds		500
Cash and cash equivalents	115,698	100,206
Restricted cash	852	852
Total cash, cash equivalents, and restricted cash	$ 116,550	$ 101,058