CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net loss	$ (22,397)	$ (107,500)	$ (33,693)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	122	219	208
Share-based compensation	1,757	1,237	1,283
Change in fair value of contingent consideration	(11,180)	71,620	8,800
Gain on sale of equipment	0	0	(5)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,304)	(5,188)	(913)
Accounts payable	1,200	535	460
Accrued expenses and other liabilities	(2,035)	1,556	1,031
Deferred revenue	3,000	0	0
Net Cash Used in Operating Activities	(30,837)	(37,521)	(22,829)
Cash Flows from Investing Activities:
Purchases of property and equipment	(8)	(136)	(2)
Net Cash Used in Investing Activities	(8)	(136)	(2)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock and common stock warrants, net of issuance costs	0	27,833	50,971
Proceeds from exercises of common stock warrants	131	5,481	7,315
Proceeds from issuance of common stock under ATM Offering, net of issuance costs	37,958	1,936	0
Proceeds from exercises of stock options	13	98	277
Proceeds from sales of common stock under 2014 ESPP	11	8	20
Net Cash Provided by Financing Activities	38,113	35,356	58,583
Net (Decrease) Increase in Cash, Cash Equivalents and Restricted Cash	7,268	(2,301)	35,752
Cash, Cash Equivalents and Restricted Cash - Beginning of Period	48,141	50,442	14,690
Cash, Cash Equivalents and Restricted Cash - End of Period	55,409	48,141	50,442
Cash and cash equivalents	52,389	48,121	50,422
Short term restricted cash	3,000	0	0
Long term restricted cash	20	20	20
Supplemental cash flow disclosure:
Cash paid for amounts included in the measurement of lease liabilities	154	153	0
Right-of-use assets related to the adoption of ASC 842	0	236	0
Right-of-use assets obtained in exchange for lease obligations	290	0	0
Supplemental disclosure of non-cash financing activities:
Deemed dividend on adjustment of exercise price on certain warrants	$ 147	$ 0	$ 0