Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating activities
Net loss	$ (17,550)	$ (35,520)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	664	951
Amortization of debt issuance costs	0	705
Debt extinguishment loss upon paydown of principal	0	491
Net accretion and amortization of premium and discounts on marketable securities	(638)	(1,199)
Gain on disposal of property and equipment	(23)	0
Stock-based compensation	3,165	6,127
Non-cash rent expense	(937)	(811)
Impairment of long-lived assets	0	5,602
(Gain) loss on warrant liability	(2,407)	(2,283)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,178	(1,858)
Other long-term assets	(74)	52
Accounts payable	424	(642)
Accrued compensation	(137)	(793)
Accrued liabilities and other current liabilities	375	(335)
Net cash used in operating activities	(14,960)	(29,513)
Investing activities
Purchase of marketable securities	(21,289)	(28,609)
Maturities of marketable securities	25,250	74,000
Purchase of property and equipment	0	(11)
Sale of property and equipment	26	1
Net cash provided by investing activities	3,987	45,381
Financing activities
Payment of debt principal	0	(20,000)
Payment of debt issuance costs	0	(1,563)
Proceeds from issuance of common stock under 2018 ESPP	68	91
Net cash provided by financing activities	68	(20,728)
Net decrease in cash, cash equivalents and restricted cash	(10,905)	(4,860)
Cash, cash equivalents and restricted cash at beginning of the period	20,699	13,632
Cash, cash equivalents and restricted cash at end of the period	9,794	8,772
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest	0	1,969
Cash and cash equivalents	8,898	7,876
Long-term restricted cash	896	896
Total cash, cash equivalents and restricted cash	9,794	8,772
ATM Offering Program
Financing activities
Proceeds from issuance of common stock, net of issuance costs	$ 0	$ 744