Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows used in operating activities:
Net loss	$ (9,045)	$ (10,755)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,575	1,879
Operating lease right-of-use asset	341	341
Depreciation	77	56
Amortization of premium on marketable debt securities	(71)	410
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(6,145)	(1,186)
Other assets	58	78
Accounts payable	2,495	(413)
Accrued expenses	(1,841)	(1,039)
Operating lease liabilities	(332)	(332)
Net cash used in operating activities	(12,888)	(10,961)
Cash flows from investing activities:
Purchase of marketable debt securities	(12,186)	(12,415)
Proceeds from maturity and redemption of marketable debt securities	22,052	13,171
Purchase of property and equipment	(6)	(11)
Net cash provided by investing activities	9,860	745
Cash flows from financing activities:
Repurchase of shares in connection with settlement of RSUs	(64)	(72)
Net cash used in financing activities	(64)	(72)
Net decrease in cash and cash equivalents and restricted cash	(3,092)	(10,288)
Cash and cash equivalents and restricted cash - beginning of year	24,872	36,469
Cash and cash equivalents and restricted cash - end of period	21,780	26,181
Reconciliation of cash and cash equivalents and restricted cash to the condensed consolidated balance sheets:
Cash and cash equivalents	21,035	25,436
Restricted cash, non-current	745	745
Cash and cash equivalents and restricted cash	$ 21,780	$ 26,181