Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (30,079)	$ (18,388)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,338	1,705
Depreciation and amortization	560	390
Amortization of operating lease right-of-use assets	494	531
Loss on disposal of property and equipment	0	173
Write-off of right-of-use asset upon lease termination	0	113
Unrealized foreign exchange gain	0	(21)
Changes in operating assets and liabilities:
Other current assets and other non-current assets	(1,614)	(870)
Accounts payable and accrued liabilities	(1,157)	1,230
Operating lease right-of-use assets	0	(169)
Operating lease liabilities	(176)	72
Net cash used in operating activities	(26,634)	(15,234)
Investing activities
Purchase of property and equipment	(2,280)	(1,079)
Net cash used in investing activities	(2,280)	(1,079)
Financing activities
Proceeds from exercise of stock options	376	3,695
Proceeds from the issuance of common stock under Employee Stock Purchase Plan	219	0
Payment on finance lease obligations	(2)	(4)
Net cash provided by financing activities	593	3,691
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	0	3
Net change in cash, cash equivalents, and restricted cash during the period	(28,321)	(12,619)
Cash, cash equivalents, and restricted cash, beginning of period	193,434	143,093
Cash, cash equivalents, and restricted cash, end of period	165,113	130,474
Supplemental disclosure of non-cash investing and financing activities:
Operating lease liabilities arising from obtaining ROU asset	1,584	9,614
Purchases of property and equipment unpaid at period-end	419	405
Offering costs unpaid at period-end	$ 0	$ 255