STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows used in operating activities:
Net loss	$ (121,832)	$ (115,438)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,169	1,324
Noncash lease expense	1,936	1,718
Stock-based compensation	25,616	25,144
Amortization of premium and discount on marketable securities, net	(3,473)	2,591
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(297)	(3,843)
Accounts payable	(2,270)	(347)
Accrued expenses and other liabilities	2,522	6,833
Long-term prepaid expenses and other long-term assets	(8,810)
Operating lease liabilities	(1,624)	(1,711)
Net cash used in operating activities	(107,063)	(83,729)
Cash flows (used in) provided by investing activities:
Purchases of marketable securities	(221,633)	(119,223)
Proceeds from maturities of marketable securities	190,500	203,933
Purchases of property and equipment	(3,513)	(3,019)
Net cash (used in) provided by investing activities	(34,646)	81,691
Cash flows provided by financing activities:
Proceeds from issuance of common stock and pre-funded warrants, net of offering costs	135,731
Proceeds from issuance of common stock in connection with the exercise of stock options	47	389
Proceeds from the issuance of common stock under ESPP	634	426
Payment of withholding taxes related to stock-based compensation to employees	(17)
Net cash provided by financing activities	136,395	815
Net decrease in cash and cash equivalents	(5,314)	(1,223)
Cash, cash equivalents and restricted cash at beginning of year	34,649	35,872
Cash, cash equivalents and restricted cash at end of year	29,335	34,649
Supplemental disclosures:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	16,680	1,803
Property and equipment in accounts payable	163	90
Unrealized gain (loss) on marketable securities	1,915	$ (981)
Offering costs in accrued expenses and other current liabilities	$ 131