Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (12,449)	$ (10,157)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	250	307
Stock-based compensation	536	408
Fair value adjustment for preferred stock tranche rights and anti-dilution warrants liabilities	(1,265)	(296)
Deferred rent	(14)	(5)
Changes in operating assets and liabilities:
Grants receivable	4,962	(1,586)
R&D tax credits receivable	(238)	(282)
Prepaid expenses and other current assets	(580)	(376)
Accounts payable	1,055	508
Accrued expenses and other liabilities	(886)	(234)
Deferred income	(852)	1,055
Net cash used in operating activities	(9,481)	(10,658)
Cash flows from investing activities
Purchase of property and equipment	(119)	(673)
Purchase of other assets	(19)	(121)
Net cash used in investing activities	(138)	(794)
Cash flows from financing activities
Proceeds from issuance of common stock and profit certificates upon exercise of options	205	102
Payment of IPO costs	(1,311)
Proceeds from grants repayable	2,713
Net cash provided by financing activities	126,633	22,474
Effects of exchange rate changes on cash and restricted cash	(11)	184
Net increase in cash and restricted cash	117,003	11,206
Cash and restricted cash at beginning of period	19,990	22,054
Cash and restricted cash at end of period	136,993	33,260
Non-cash investing and financing activities
Accretion of Series B and B-2 Preferred Stock to redemption value	4,189	1,612
Settlement of preferred stock tranche right	4,135
Deferred IPO costs in accounts payable	400
Supplemental disclosure of cash flows
Cash paid for taxes	147	2
Series B-2 Preferred Stock
Cash flows from financing activities
Proceeds from issuance of Preferred Stock	125,358
Payment of issuance costs on Series B-2 Preferred Stock	$ (332)
Series B Preferred Stock
Cash flows from financing activities
Proceeds from issuance of Preferred Stock		$ 22,372