CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (48,256)	$ (57,433)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,860	3,117
Amortization of premiums and discounts on marketable securities	(432)	2,594
Stock-based compensation	6,204	7,182
Noncash operating lease expense	426
Changes in operating assets and liabilities:
Prepaid expenses and other assets	38	234
Accounts payable	(1,668)	(95)
Accrued liabilities and other liabilities	(907)	(536)
Lease liabilities	(485)
Other long-term liabilities	(84)
Net cash used in operating activities	(42,304)	(44,937)
Cash flows from investing activities:
Sales and maturities of marketable securities	97,605	78,029
Purchases of marketable securities	(61,688)	(13,267)
Purchases of property and equipment	(807)	(1,251)
Net cash provided by investing activities	35,110	63,511
Cash flows from financing activities:
Proceeds from exercise of stock options	5	66
Proceeds from shares issued under ESPP	78	73
Net cash provided by financing activities	83	139
Net increase (decrease) in cash and cash equivalents	(7,111)	18,713
Cash and cash equivalents - beginning of period	26,630	12,376
Cash and cash equivalents - end of period	19,519	31,089
Supplemental disclosures of cash flow information:
Cash paid for interest	$ 62	$ 68