Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities:
Net loss	$ (19,959)	$ (25,175)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,102	2,195
Right-of-use asset (accretion) amortization	(98)	0
Stock-based compensation	2,898	3,453
Asset impairment	14,893	0
Realized investment (losses) gains	(53)	(299)
Other non-cash transactions	(129)	216
Changes in operating assets and liabilities	(33,804)	(27,389)
Net cash used in operating activities	(34,150)	(46,999)
Investing activities:
Purchases of property and equipment	(184)	(1,052)
Proceeds from maturity of investments	24,007	21,900
Purchases of investments	(15,270)	(43,191)
Net cash provided by (used in) investing activities	8,553	(22,343)
Financing activities:
Proceeds from exercise of stock options	0	95
Proceeds from employee stock purchase plan	52	104
Proceeds from issuance of common stock resulting from ATM sales, net of $0.7 million and $0.3 million in transaction costs, respectively	19,729	6,922
Net cash provided by financing activities	19,781	7,121
Effect of exchange rate change on cash and cash equivalents	75	(7,120)
Net decrease in cash and cash equivalents	(5,741)	(69,341)
Cash and cash equivalents at beginning of period	38,635	117,764
Cash and cash equivalents at end of period	32,894	48,423
Supplemental cash flow disclosures:
Net unrealized gain on investments	74	82
Property and equipment included in accounts payable	$ 0	$ 31