Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (26,366)	$ (29,581)
Adjustments to reconcile net loss to net cash (used in) operating activities:
Depreciation and amortization	65	376
Net loss on disposal of property and equipment	0	6,322
Loss on lease termination	0	881
Share-based compensation expense	3,466	4,652
Changes in operating assets and liabilities:
Accounts receivable	(127)	0
Related party accounts receivable	0	127
Prepaid expenses	281	50
Other current assets	(14)	(121)
Operating lease assets	92	1,344
Other assets	183	183
Accounts payable	939	237
Related party accounts payable	0	(286)
Accrued research and development costs	(1,594)	819
Operating lease liabilities	0	(1,048)
Accrued expenses and other current liabilities	(578)	(3,919)
Net cash (used in) operating activities	(23,653)	(19,964)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sale of property and equipment	0	1,464
Net cash provided by investing activities	0	1,464
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from equity private placement and ATM	0	30,497
Proceeds from exercises of stock options and ESPP	17	160
Net cash provided by financing activities	17	30,657
Effect of exchange rate changes on cash and cash equivalents	(2)	1
Net decrease in cash, cash equivalents and restricted cash	(23,638)	12,158
Cash, cash equivalents and restricted cash, beginning of period	53,961	58,232
Cash, cash equivalents and restricted cash, end of period	30,323	70,390
Supplemental cash flow disclosure:
Cash and cash equivalents	30,323	70,390
Total cash, cash equivalents and restricted cash	$ 30,323	$ 70,390