Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net loss	$ (14,768)	$ (8,112)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	79	68
Stock-based compensation	1,520	503
Non-cash interest expense	62	70
Amortization (accretion) of premiums/discounts on investments, net	170	(59)
Amortization of right-of-use asset	164	152
Change in fair value of warrant liability		106
Changes in operating assets and liabilities
Prepaid expenses and other current assets	(410)	(6)
Accounts payable and accrued liabilities	1,189	(1,190)
Lease liability	(176)	(134)
Net cash used in operating activities	(12,170)	(8,602)
Investing activities:
Purchases of property and equipment		(73)
Purchases of short-term investments	(12,784)	(7,944)
Sale and maturities of short-term investments	19,395	13,690
Net cash provided by investing activities	6,611	5,673
Financing activities:
Proceeds from exercise of common stock options	623	3
Repurchase of unvested common stock		(2)
Payment of initial public offering costs		(10)
Net cash provided by (used in) financing activities	623	(9)
Net decrease in cash and cash equivalents	(4,936)	(2,938)
Cash and cash equivalents at beginning of period	24,393	15,668
Cash and cash equivalents at end of period	19,457	12,730
Supplemental disclosure of cash flow information:
Cash paid for interest	181	183
Supplemental non-cash investing and financing activities:
Issuance costs in accounts payable and accrued liabilities		229
Change in unpaid property and equipment purchases		69
Vesting of common stock	$ 8	$ 24