Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (10,274,000)	$ (6,976,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,193,000	2,097,000
Stock-based compensation	2,956,000	344,000
Non-cash interest expense		64,000
Non-cash interest expense related to sale of future royalties	937,000	1,060,000
Non-cash revenue related to sale of future royalties	(2,800,000)	(3,132,000)
Change in operating assets and liabilities:
Accounts receivable	3,392,000	1,761,000
Prepaid expenses and other assets	(657,000)	530,000
Accounts payable	148,000	(347,000)
Other accrued liabilities	1,376,000	(371,000)
Net cash used in operating activities	(3,729,000)	(4,970,000)
Cash flows from investing activities:
Purchase of property and equipment	(13,000)	(711,000)
Proceeds from sale of equipment	3,000
Net cash used in investing activities	(10,000)	(711,000)
Cash flows from financing activities:
Net proceeds from issuance of securities in registered direct offering	9,175,000	2,540,000
Net proceeds from issuance of common stock, pre-funded warrants and common warrants in April 2019 underwritten offering		8,074,000
Proceeds from issuance of common stock upon exercise of pre-funded warrants		652,000
Proceeds from issuance of common stock upon exercise of common stock warrants	24,658,000
Proceeds from issuance of common stock upon exercise of stock options	116,000
Disgorgement of short-swing profits, net of costs	652,000
Repayment of principal on secured promissory note payable to Oxford Finance		(833,000)
Net cash provided by financing activities	34,601,000	10,433,000
Net increase in cash and cash equivalents	30,862,000	4,752,000
Cash, cash equivalents and restricted cash at beginning of the period	13,526,000	11,506,000
Cash, cash equivalents and restricted cash at end of the period	44,388,000	16,258,000
Supplemental disclosure of cash flow information:
Interest paid		136,000
Supplemental disclosure of non-cash financing activity:
Issuance of warrants to placement agent’s representatives	453,000	100,000
Issuance of warrants to underwriters’ designees		333,000
Acquisition of property and equipment included in accounts payable	$ 170,000	$ 47,000