CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities
Net loss	$ (190,418)	$ (168,710)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	398	723
Non-cash lease expense	7,893	1,842
Impairment costs	18,570
Accretion of short-term investment discounts	(3,698)	(1,076)
Stock-based compensation expense	40,779	41,315
Changes in operating assets and liabilities:
Interest receivable	(49)	(107)
Prepaid expenses and other current assets and prepaid expenses to related party	5,614	(3,028)
Other assets	(900)	490
Income tax payable	(128)	(879)
Accounts payable, accrued expenses, other liabilities and amount due to related party	(2,512)	(12,622)
Net cash used in operating activities	(124,451)	(142,052)
Cash flows from investing activities
Purchase of short-term investments	(125,827)	(228,806)
Maturities of short-term investments	163,812	148,328
Net cash provided by (used in) investing activities	37,985	(80,478)
Cash flows from financing activities
Proceeds from issuance of common stock in public offering, net of underwriting discounts, commissions and offering costs	70,169
Proceeds from issuance of common stock in registered direct offering, net of issuance costs		126,425
Proceeds from issuance of stock under the 2020 Employee Stock Purchase Plan	326	536
Net cash provided by financing activities	70,495	126,961
Net decrease in cash, cash equivalents, and restricted cash	(15,971)	(95,569)
Cash, cash equivalents, and restricted cash at beginning of period	106,944	202,513
Cash, cash equivalents, and restricted cash at end of period	90,973	106,944
Non-cash investing and financing activities
Unrealized gain (loss) on available-for-sale securities	406	(313)
Right-of-use assets obtained in exchange for operating lease liability		14,717
Reduction of right-of-use asset due to modification and remeasurement	(4,904)	(5,506)
Purchase of property and equipment included in AP and accrued expenses		104
Supplemental disclosure of cash flows
Income taxes paid, net of refunds	220	613
Cash and cash equivalents	90,121	106,092
Restricted cash	852	852
Total cash, cash equivalents, and restricted cash	$ 90,973	$ 106,944