CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (14,639)	$ (10,257)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,056	947
Depreciation expense	25	25
Amortization and accretion on investments	48	55
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,210)	(2,586)
Accounts payable	(476)	1,030
Accrued expenses and other current liabilities	(1)	(2,226)
Operating lease assets and liabilities, net	37	(8)
Net cash used in operating activities	(17,160)	(13,020)
Cash flows from investing activities:
Proceeds from maturities and sales of short-term investments	5,470	22,037
Purchases of short-term investments		(3,722)
Purchases of property and equipment	(135)	(12)
Net cash provided by investing activities	5,335	18,303
Cash flows from financing activities:
Payment of issuance costs		(12)
Proceeds from exercise of options		472
Net cash provided by financing activities		460
Net increase (decrease) in cash, cash equivalents and restricted cash	(11,825)	5,743
Cash, cash equivalents and restricted cash, beginning of period	48,484	47,786
Cash, cash equivalents and restricted cash, end of period	36,659	53,529
Supplemental disclosure of non-cash investing and financing activities:
Deferred offering costs included in accounts payable and accrued expenses		208
Right of use asset obtained in exchange for lease liabilities	1,886
Purchases of property and equipment included in accrued expenses	228	12
Unrealized loss on investments	$ (35)	$ (2)