Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities:
Net loss	$ (19,142)	$ (30,353)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	68	154
Stock-based compensation	3,282	3,106
Non-cash interest expense	313	126
Amortization (accretion) of premiums/discounts on investments, net	(4)	263
Amortization of right-of-use asset	179	331
Gain from lease termination and asset sale	(508)
Changes in operating assets and liabilities
Prepaid expenses and other current assets	(1,298)	1,006
Accounts payable and accrued liabilities	(4,281)	3,425
Lease liability	(196)	(361)
Net cash used in operating activities	(21,587)	(22,303)
Investing activities:
Purchases of property and equipment		(8)
Proceeds from asset sale	700
Purchases of short-term investments	(12,676)	(34,681)
Sales and maturities of short-term investments	30,000	48,541
Net cash provided by investing activities	18,024	13,852
Financing activities:
Proceeds from exercise of common stock options		1,059
Repurchase of unvested common stock		(1)
Proceeds from issuance of common stock from employee stock purchase plan	1	147
Net cash provided by financing activities	1	1,205
Net decrease in cash and cash equivalents	(3,562)	(7,246)
Cash and cash equivalents at beginning of period	48,910	24,393
Cash and cash equivalents at end of period	45,348	17,147
Supplemental disclosure of cash flow information:
Cash paid for interest	601	367
Supplemental non-cash investing and financing activities:
Vesting of common stock	$ 3	$ 15