CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net loss	$ (64,763)	$ (58,489)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	4,092	4,571
Depreciation and amortization expense	389	367
Non-cash lease expense	1,104	1,031
Accretion of debt discount	653	557
Other	255	283
Changes in operating assets and liabilities:
Prepaid expenses, other current assets and research and development incentive receivable	158	(14)
Accounts payable	(481)	(695)
Accrued expenses	1,305	1,069
Lease liabilities	(721)	(473)
Operating lease right-of-use asset, net of non-cash portion	0	59
Net cash used in operating activities	(58,009)	(51,852)
Cash flows from investing activities:
Acquisition of property, equipment and intangible assets	(69)	(602)
Net cash used in investing activities	(69)	(602)
Cash flows from financing activities:
Proceeds from exercise of stock options and pre-funded warrants and issuance of shares of common stock under employee stock purchase plan	70	157
Employee taxes paid related to net share settlement of vested restricted stock units	(12)	0
Issuance costs related to sale of warrants and fees paid for amendments to loan and security agreement	(3,300)	0
Repayments of Secured Debt	(795)	0
Proceeds from sale of shares of common stock, redeemable common stock, warrants and pre-funded warrants, net of issuance costs	60,623	51,518
Settlement and retirement of redeemable common stock	0	(2,000)
Net cash provided by financing activities	56,586	49,675
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(468)	(203)
Net decrease in cash, cash equivalents and restricted cash	(1,960)	(2,982)
Cash, cash equivalents and restricted cash at beginning of period	83,108	80,702
Cash, cash equivalents and restricted cash at end of period	81,148	77,720
Supplemental disclosure of non-cash investing and financing activities:
Acquisition of right-of-use asset financed by lease liabilities	0	1,343
Issuance costs not yet paid related to sale of shares of common stock, redeemable common stock and pre-funded warrants	$ 22	$ 0