Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (151,759)	$ (112,033)	$ (100,777)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	21,497	23,243	10,054
Depreciation	29	43	41
Non-cash lease expense	234	217	203
Net amortization of premiums and discounts on short-term investments	(9,554)	(12)	1,066
Amortization of debt issuance costs and discount	448	204
Fair value change in warrant liability	79	264
Write-off of deferred offering costs	337
Unrealized foreign exchange gain and loss	(8)	16	5
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(6,740)	2,112	(2,101)
Accounts payable	(645)	968	3,273
Accrued expenses and other current liabilities	946	(7,333)	8,737
Operating lease liability	(231)	(206)	(182)
Net cash used in operating activities	(145,367)	(92,517)	(79,681)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of short-term and long-term marketable securities	(433,123)	(101,446)	(43,561)
Proceeds from maturities of short-term marketable securities	209,500	37,621	85,841
Net cash (used in) provided by investing activities	(223,623)	(63,825)	42,280
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the exercise of stock options	3,267	5,016	750
Proceeds from the issuance of common stock pursuant to employee stock purchase plan purchases	396	280	373
Proceeds from the issuance of common in a follow-on public offering		216,200
Proceeds from the issuance of common stock pursuant to the ATM offering	124,212
Proceeds from the issuance of common stock pursuant to registered direct offering	211,217
Proceeds from the issuance of common stock pursuant to private offering		25,000
Proceeds from loan payable	15,000	10,000
Payment of debt and equity issuance costs	(776)	(864)	(521)
Net cash provided by financing activities	353,316	255,632	602
Net (decrease) increase in cash, cash equivalents and restricted cash	(15,674)	99,290	(36,799)
Cash, cash equivalents and restricted cash at the beginning of the period	249,881	150,591	187,390
Cash, cash equivalents and restricted cash at the end of the period	234,207	249,881	150,591
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	2,483	441
NON-CASH INVESTING AND FINANCING INFORMATION:
Change in net unrealizable gain (loss) on marketable securities	$ 233	64	$ (24)
Warrant liability costs reclassified to additional paid-in equity on vested warrants issued	330
Debt and equity issuance costs included in accounts payable and accrued expenses and other current liabilities		285
Deferred offering costs reclassified to additional paid-in equity	$ 364	$ 150