CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (11,138)	$ (10,873)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	613	262
Depreciation and amortization expense	36	20
Non-cash lease expense	158	119
Accretion of debt discount	119	153
Loss on extinguishment of debt	162	0
Change in fair value of preferred stock warrant liability	0	288
Change in fair value of derivative liability	0	(183)
Other	70	0
Changes in operating assets and liabilities:
Accounts receivable	(3,000)	0
Prepaid expenses, other current assets and research and development incentive receivable	(869)	(595)
Accounts payable	(800)	1,332
Accrued expenses	(668)	(2,072)
Lease liabilities	(210)	(201)
Net cash used in operating activities	(15,527)	(11,750)
Cash flows from investing activities:
Cash, cash equivalents and restricted cash acquired in connection with the Merger	0	26,406
Acquisition of property, equipment and intangible assets	(555)	0
Net cash provided by investing activities	(555)	26,406
Cash flows from financing activities:
Proceeds from exercise of stock options and warrants	96	113
Proceeds from borrowings under loan and security agreements, net of issuance costs	4,888	0
Net cash provided by financing activities	4,984	113
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(34)	(21)
Net (decrease) increase in cash, cash equivalents and restricted cash	(11,132)	14,748
Cash, cash equivalents and restricted cash at beginning of period	128,086	8,498
Cash, cash equivalents and restricted cash at end of period	116,954	23,246
Supplemental disclosure of non-cash investing and financing activities:
Issuance costs not yet paid	20	0
Conversion of convertible preferred stock into common stock	0	64,675
Conversion of redeemable common stock into common stock	0	734
Conversion of convertible preferred stock warrants into common stock warrants	0	5,235
Fair value of net assets acquired in the Merger	$ 0	$ 46,358