Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (21,935)	$ (39,276)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	0	577
Stock-based compensation expense	971	1,971
Amortization of premium on marketable securities	44	1,150
Non-cash loss on termination of lease	0	137
Gain on sale of equipment	0	(210)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	360	415
Accounts payable	(2,129)	(9,473)
Other liabilities	2,212	(1,016)
Net cash used in operating activities	(20,477)	(45,771)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	0	(7)
Proceeds from sale of property and equipment	0	236
Purchases of available-for-sale marketable securities	0	(3,671)
Proceeds from sales and maturities of marketable securities	7,775	77,502
Net cash provided by (used in) investing activities	7,775	74,060
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of pre-funded warrants for the purchase of common stock, net of issuance costs	16,567	0
Repurchase and retirement of common stock	(3,000)	0
Net cash provided by financing activities	13,567	0
Net change in cash, cash equivalents and restricted cash	865	28,289
Cash and cash equivalents at beginning of period	36,640	8,305
Effect of exchange rates on cash	44	46
Cash and cash equivalents at end of period	37,549	36,640
Supplemental non-cash disclosure: NONCASH INVESTING AND FINANCING ACTIVITY:
Non-cash gain on sale of fixed assets	0	14
Operating right-of-use asset obtained in exchange for operating lease liability	0	824
Derecognition of operating right-of-use asset and operating lease liability upon termination of lease	0	714
Unrealized loss on available-for-sale marketable securities	57	168
Non-cash deferred financing costs	$ 0	$ 25