CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net loss	$ (33,863)	$ (15,714)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	6	30
Amortization of right-of-use asset and lease liability	(46)	(41)
Stock-based compensation expense	1,483	1,313
Amortization of deferred financing costs, debt discounts and premiums and discounts on available-for-sale marketable securities	(419)	(36)
Change in fair value of preferred stock tranche liability	6,011	(3,430)
Changes in operating assets and liabilities:
Accounts receivable, net		31
Grant receivable	(226)
Prepaid expenses, other current assets and other assets	(647)	(2,089)
Accounts payable	265	2
Accrued expenses and other liabilities	(544)	(1,045)
Deferred liabilities	(327)	693
Net cash used in operating activities	(28,307)	(20,286)
Investing activities
Purchases of property and equipment	(21)
Purchases of investments		(13,804)
Maturities of investments	31,000	13,000
Net cash provided by (used in) investing activities	30,979	(804)
Financing activities
Proceeds from issuance of Series B Convertible Preferred Stock, net		28,099
Proceeds from long-term debt, net		14,918
Fees paid to Lenders for Loan Agreement amendment	(150)
Proceeds from insurance premium financing	1,298	1,430
Payments on insurance premium financing	(387)	(426)
Proceeds from the exercise of stock options and employee stock purchase program	85	29
Net cash provided by financing activities	846	44,050
Increase in cash, cash equivalents and restricted cash	3,518	22,960
Cash, cash equivalents and restricted cash at beginning of period	79,076	79,076
Cash, cash equivalents and restricted cash at end of period	82,594	98,749
Supplemental disclosure of non-cash investing and financing activities
Issuance of preferred stock tranche liability		$ 6,940
Purchases of property and equipment including in accounts payable and accrued expenses	$ 7