Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (57,557)	$ (60,692)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	8,829	11,557
Depreciation and amortization	1,561	1,306
Amortization of operating lease right-of-use assets	1,051	971
Amortization and accretion of premiums/discounts on available-for-sale securities	(494)	0
Loss on disposal of property and equipment	118	0
Changes in operating assets and liabilities:
Other current assets and non-current assets	(206)	129
Accounts payable and accrued liabilities	2,256	(142)
Operating lease liabilities	(1,165)	(687)
Net cash used in operating activities	(45,607)	(47,558)
Investing activities
Purchases of property and equipment	(1,110)	(3,263)
Purchase of available-for-sale securities	(107,524)	0
Proceeds from maturities of available-for-sale securities	49,500	0
Net cash used in investing activities	(59,134)	(3,263)
Financing activities
Proceeds from exercise of stock options	134	411
Payment on finance lease obligations	(55)	(51)
Proceeds from issuance of common stock under Employee Stock Purchase Plan	82	372
Net cash provided by financing activities	161	732
Net change in cash, cash equivalents, and restricted cash during the year	(104,580)	(50,089)
Cash, cash equivalents, and restricted cash at beginning of year	143,345	193,434
Cash, cash equivalents, and restricted cash at end of year	38,765	143,345
Supplemental disclosure:
Operating lease liabilities arising from obtaining right-of-use asset	0	1,584
Finance lease liabilities arising from obtaining right-of-use asset	307	0
Purchase of property and equipment unpaid at period end	$ 283	$ 412