STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (102,050)	$ (40,636)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	453	412
Stock-based compensation	5,741	6,850
Change in fair value of derivative liabilities		(46)
Non-cash inducement warrant expense	60,751
(Increase) decrease in:
Receivables	(1,577)	(1,002)
Prepaid expenses and other current assets	(3,047)	5,406
Other noncurrent assets	9,432	(4,684)
Deposits	(2)
Increase (decrease) in:
Accounts payable	219	(3,148)
Accrued expenses	810	(532)
Deferred revenue		(146)
Deferred rent	17	(112)
Other liabilities	7
Net cash used in operating activities	(29,246)	(37,638)
Cash flows from investing activities:
Purchases of property and equipment	(184)	(545)
Net cash used in investing activities	(184)	(545)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,020	240
Repurchase of common stock	(370)	(1,275)
Issuance of common stock in connection with at the market offering, net	2,971
Issuance of common stock upon exercise of warrants, net	52,499
Net cash provided by (used in) financing activities	56,120	(1,035)
Net increase (decrease) in cash and cash equivalents, and restricted cash	26,690	(39,218)
Cash and cash equivalents, and restricted cash, beginning of period	61,729	71,335
Cash and cash equivalents, and restricted cash, end of period	88,419	32,117
Supplementary disclosure of cash flow information:
Compensation paid in restricted stock, gross	$ 1,000
Series 1 Preferred Stock
Supplementary disclosure of noncash investing and financing activities:
Payment of dividends in preferred stock		$ 16,656