Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (23,438)	$ (16,720)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Share-based compensation expense	3,440	1,181
Depreciation and amortization	615	443
Change in fair value of warrant liability	0	5,381
Changes in operating assets and liabilities:
Accounts receivable	(332)	4,955
Research and development incentives receivable	(4,446)	(3,518)
Prepaid expenses and other current assets	267	(60)
Operating lease right-of-use assets	374	352
Other assets	(292)	(124)
Accounts payable	1,325	530
Accrued expenses and other current liabilities	2,050	(978)
Lease liabilities	4	(351)
Deferred revenue	29,013	(4,329)
Other long-term liabilities	233	429
Net cash provided by (used in) operating activities	8,813	(12,809)
Cash used in investing activities:
Purchases of property and equipment	(621)	(881)
Net cash used in investing activities	(621)	(881)
Cash flows from financing activities:
Proceeds from the issuance of ADSs in initial public offering, net of issuance costs		57,768
Proceeds from the exercise of share options and sale of ordinary shares	11	21
Proceeds from the exercise of warrants	1	6
Net cash provided by financing activities	12	59,129
Effect of exchange rate changes on cash	(3,411)	(283)
Net increase in cash	4,793	45,156
Cash at beginning of period	92,117	63,380
Cash at end of period	96,910	108,536
Supplemental disclosure of cash flow information
Cash paid for income taxes	38	73
Public offering costs accrued but not paid	274	664
Cash paid for amounts included in the measurement of operating lease liabilities	406	447
Purchases of property and equipment included in accounts payable and accrued expenses	$ 12
Conversion of convertible preferred shares to ordinary shares upon closing of the initial public offering		123,780
Reclassification of warrant liability to additional paid-in capital		10,021
Series B2 Convertible Preferred Shares
Cash flows from financing activities:
Proceeds from issuance of convertible preferred shares, net of issuance costs		$ 1,334