Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net loss	$ (6,566)	$ (16,414)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	55	83
Net amortization of premiums and discounts on investments	(155)	(21)
Stock-based compensation expense	691	1,217
Loss on disposal of fixed assets	16
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	345	1,076
Other assets	24
Accounts payable	(1,584)	531
Operating lease liabilities	(33)	(62)
Accrued expenses and other current liabilities	(570)	105
Net cash used in operating activities	(7,777)	(13,485)
Cash flows from investing activities:
Purchases of investments		(12,098)
Proceeds from sales or maturities of investments	15,750	29,611
Net cash provided by investing activities	15,750	17,513
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash	7,973	4,028
Cash, cash equivalents and restricted cash at beginning of period	5,219	3,625
Cash, cash equivalents and restricted cash at end of period	$ 13,192	$ 7,653