CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (15,387,000)	$ (15,974,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	17,000	19,000
Amortization expense - right-of-use leased assets - operating	177,000	159,000
Accretion of discount on investments	(1,000)
Stock-based compensation	1,129,000	681,000
Non-cash interest expense	246,000	173,000
Fair value adjustment to derivative liability	30,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	(259,000)	107,000
Accounts payable, accrued expenses and other liabilities	343,000	4,806,000
Net cash used in operating activities	(13,705,000)	(10,029,000)
Cash flows from investing activities
Purchases of short term investments	(40,469,000)
Net cash used in investing activities	(40,469,000)
Cash flows from financing activities
Proceeds from common stock offering, net	50,191,000
Proceeds from at-the-market offering, net	10,388,000
Proceeds from the exercise of vested stock options	715,000	18,000
Payment of term loan exit fee	(800,000)
Settlements of restricted stock units for tax withholding obligations	(84,000)
Net cash provided by financing activities	60,410,000	18,000
Net (decrease) increase in cash, cash equivalents and restricted cash	6,236,000	(10,011,000)
Cash, cash equivalents and restricted cash at beginning of period	72,806,000	89,660,000
Cash, cash equivalents and restricted cash at end of period	79,042,000	79,649,000
Supplemental cash flow information
Interest paid	1,436,000	608,000
Taxes paid	$ 144,000	$ 256,000