Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net loss	$ (89,998)	$ (50,986)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	688	632
Stock-based compensation expense	9,996	7,324
Accretion of development financing liability	2,583
Write-off of deferred financing costs	312
Net accretion and amortization of investments in marketable securities	637	(104)
Changes in assets and liabilities:
Other prepaid expenses and current assets	386	6,716
Other assets	(1,513)	(47)
Accounts payable	2,309	(2,272)
Accrued research and development expenses	5,054	(4,520)
Other accrued liabilities	115	(1,468)
Net cash used in operating activities	(69,431)	(44,725)
Investing activities
Purchases of property and equipment	(87)	(21)
Purchases of marketable securities	(78,084)	(176,300)
Proceeds from maturities of marketable securities	126,760	224,278
Net cash provided by investing activities	48,589	47,957
Financing activities
Proceeds from issuance of common stock and pre-funded warrants, net of issuance costs	70,499
Proceeds from development financing, net of transaction costs	47,737
Proceeds from issuance of common stock pursuant to equity award plans	219	92
Net cash provided by financing activities	118,455	92
Net increase in cash and cash equivalents	97,613	3,324
Cash and cash equivalents at beginning of period	28,193	24,869
Cash and cash equivalents at end of period	125,806	28,193
Supplemental disclosure
Cash paid for amounts included in the measurement of lease liabilities	666	647
Supplemental non-cash investing and financing activities
Unpaid financing costs	$ 464