CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities
Net loss	$ (85,908)	$ (78,969)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	16,013	15,922
Depreciation	1,168	2,823
(Accretion of discount) amortization of premium on marketable securities	(3,084)	793
Non-cash lease expense	1,029	957
Other non-cash expenses	1,044	434
Changes in operating assets and liabilities:
Related party receivable from collaboration	6,844	(1,729)
Prepaid expenses and other assets	301	(4,249)
Accounts payable	(2,256)	1,627
Accrued and other liabilities	(14,915)	(9,740)
Operating lease liability	(2,634)	(2,481)
Contract liabilities	323	(11,277)
Net cash used in operating activities	(82,075)	(85,889)
Investing activities
Proceeds from maturities of marketable securities	110,170	122,336
Purchase of marketable securities	(49,170)	(144,048)
Purchases of property and equipment	(774)	(1,107)
Net cash provided by (used in) investing activities	60,226	(22,819)
Financing activities
Proceeds from employee stock purchase plan	996	1,228
Proceeds from exercise of stock options	668	1,661
Proceeds from Open Market Sale Agreement, net	0	17,403
Net cash provided by financing activities	1,664	20,292
Net decrease in cash and cash equivalents	(20,185)	(88,416)
Cash, cash equivalents and restricted cash, at beginning of period	77,410	153,294
Cash, cash equivalents and restricted cash, at end of period	57,225	64,878
Supplemental disclosures of non-cash investing and financing activities:
Property and equipment purchases not yet paid	$ 273	$ 54