Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities:
Net loss	$ (30,353)	$ (17,434)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	154	140
Stock-based compensation	3,106	1,360
Non-cash interest expense	126	141
Amortization (accretion) of premiums/discounts on investments, net	263	(80)
Amortization of right-of-use asset	331	306
Change in fair value of warrant liability		120
Changes in operating assets and liabilities
Prepaid expenses and other current assets	1,006	(398)
Accounts payable and accrued liabilities	3,425	64
Lease liability	(361)	(275)
Net cash used in operating activities	(22,303)	(16,056)
Investing activities:
Purchases of property and equipment	(8)	(165)
Purchases of short-term investments	(34,681)	(7,944)
Sales and maturities of short-term investments	48,541	25,890
Net cash provided by investing activities	13,852	17,781
Financing activities:
Proceeds from exercise of common stock options	1,059	11
Repurchase of unvested common stock	(1)	(2)
Proceeds from issuance of common stock from employee stock purchase plan	147
Payment of initial public offering costs		(272)
Net cash provided by (used in) financing activities	1,205	(263)
Net (decrease) increase in cash and cash equivalents	(7,246)	1,462
Cash and cash equivalents at beginning of period	24,393	15,668
Cash and cash equivalents at end of period	17,147	17,130
Supplemental disclosure of cash flow information:
Cash paid for interest	367	369
Supplemental non-cash investing and financing activities:
Unpaid initial public offering costs		299
Vesting of common stock	$ 15	$ 49