CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (39,537)	$ (39,691)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of contingent consideration liability	86	(120)
Impairment loss on construction-in-progress		8,070
Stock-based compensation expense	4,081	2,703
Depreciation and amortization	172	149
Unrealized (gains) losses on foreign currency exchange	(134)	10
Changes in operating assets and liabilities:
Accounts receivable	233	(94)
Prepaid expenses and other current assets	3,397	(7,156)
Accounts payable	838	809
Accrued expenses and other liabilities	1,124	(4,051)
Income tax and R&D incentive receivables	(490)	875
Net cash used in operating activities	(30,230)	(38,496)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales and maturities of short-term investments		63,712
Purchases of short-term investments	(48,949)	(7,424)
Purchases of property and equipment, net	(28)	(11,900)
Cash paid for internally developed patents		(145)
Net cash (used in) provided by investing activities	(48,977)	44,243
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments of deferred offering costs	(36)	(118)
Proceeds from issuance of common stock in at-the-market offerings, net	24,337	52,356
Proceeds from issuance of common stock from Employee Stock Purchase Plan	113	106
Proceeds from exercises of stock options, net	350	94
Net cash provided by financing activities	24,764	52,438
Net (decrease) increase in cash and cash equivalents and restricted cash	(54,443)	58,185
Cash, cash equivalents and restricted cash at beginning of period	190,335	115,952
Cash, cash equivalents and restricted cash at end of period	135,892	$ 174,137
SUPPLEMENTAL NON-CASH ACTIVITIES:
Common stock issued related to contingent consideration liability	$ 6,176