CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (43,047)	$ (16,525)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	111	74
Stock-based compensation	1,046	508
Loss from remeasurement of development derivative liability	4,162	0
Non-cash interest expense	261	254
Non-cash research and development expense	5,735	0
Other non-cash transactions	100	0
Changes in operating assets and liabilities:
Other receivables	1,233	(948)
Prepaid expenses and other assets	(7,107)	(2,008)
Accounts payable	4,302	1,243
Accrued expenses and other current liabilities	419	(1,463)
Net cash used in operating activities	(32,785)	(18,865)
Investing activities
Purchases of property and equipment	(1,079)	(429)
Acquisition of intellectual property rights	(100)	0
Net cash used in investing activities	(1,179)	(429)
Financing activities
Proceeds from development derivative liability	12,649	0
Proceeds from issuance of common stock in public offering, net	472	46,308
Payments of deferred stock offering costs	(175)	0
Long-term borrowings, net	0	3,089
Proceeds from exercise of stock options	18	126
Repayments of long-term debt	0	(938)
Net cash provided by financing activities	12,964	48,585
Net (decrease) increase in cash and cash equivalents	(21,000)	29,291
Cash, cash equivalents and restricted cash at the beginning of the period	74,025	61,051
Cash, cash equivalents and restricted cash at the end of the period	53,025	90,342
Supplemental disclosure for cash flow
Cash paid for interest	496	191
Supplemental disclosure of non-cash investing and financing activities
Issuance of warrants in conjunction with development derivative liability	7,925	0
Accrued interest on term loan refinanced to principal	0	308
Issuance of warrants in conjunction with debt	0	296
Debt refinanced with new term loan	0	6,563
Initial recognition of operating lease right-of-use assets and operating lease liabilities	564	1,991
Deferred stock offering costs included in accounts payable and accrued expenses	0	31
Purchases of property and equipment included in accounts payable and accrued expenses	$ 2,741	$ 6