Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (11,620)	$ (8,694)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	922	1,308
Depreciation	21	16
Amortization of operating lease right-of-use asset	177	132
Amortization of debt discount	124	110
Change in fair value of derivative liabilities	270
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,169)	(460)
Accounts payable	1,525	4
Accrued expenses	434	31
Operating lease liabilities	(175)	(132)
Net cash used in operating activities	(9,491)	(7,685)
Cash flows from investing activities:
Purchase of property and equipment	(11)
Net cash (used in) provided by investing activities	(11)
Cash flows from financing activities:
Repayment of term loan principal		(1,250)
Proceeds from advances from collaboration partners	7,000	2,606
Payment for settlement of taxes upon vesting of restricted stock units		(94)
Net cash provided by financing activities	7,000	1,262
Increase (decrease) in cash, cash equivalents and restricted cash	(2,502)	(6,423)
Cash, cash equivalents and restricted cash at the beginning of the period	42,567	24,724
Cash, cash equivalents and restricted cash at the end of the period	40,065	18,301
Reconciliation of cash, cash equivalents and restricted cash to condensed consolidated balance sheets:
Cash and cash equivalents	39,768	18,247
Restricted cash	297	54
Cash, cash equivalents and restricted cash at the end of the period	40,065	18,301
Supplemental disclosure of cash flow activities:
Cash paid for interest	$ 297	$ 144