Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (18,359,000)	$ (12,236,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,846,000	2,854,000
Stock-based compensation	3,871,000	490,000
Non-cash interest expense		93,000
Non-cash interest expense related to sale of future royalties	1,401,000	1,560,000
Non-cash revenue related to sale of future royalties	(3,027,000)	(3,147,000)
Change in operating assets and liabilities:
Accounts receivable	3,369,000	1,237,000
Prepaid expenses and other assets	(1,384,000)	164,000
Accounts payable	810,000	136,000
Other accrued liabilities	(1,511,000)	(449,000)
Net cash used in operating activities	(12,984,000)	(9,298,000)
Cash flows from investing activities:
Purchase of property and equipment	(321,000)	(838,000)
Proceeds from sale of equipment	3,000
Net cash used in investing activities	(318,000)	(838,000)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of pre-funded warrants		1,083,000
Proceeds from issuance of common stock upon exercise of common stock warrants	25,951,000
Proceeds from issuance of common stock upon exercise of stock options	402,000
Disgorgement of short-swing profits, net of costs	652,000
Repayment of principal on secured promissory note payable to Oxford Finance		(1,250,000)
Net cash provided by financing activities	133,214,000	18,188,000
Net increase in cash and cash equivalents	119,912,000	8,052,000
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	133,438,000	19,558,000
Supplemental disclosure of cash flow information:
Interest paid		195,000
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		830,000
Operating lease liabilities arising from obtaining right-of-use assets	1,022,000	1,929,000
Acquisition of property and equipment included in accounts payable	213,000	3,000
The March 2020 Offering [Member]
Cash flows from financing activities:
Net proceeds from issuance of securities	9,175,000	2,540,000
ATM Program [Member]
Cash flows from financing activities:
Net proceeds from issuance of securities	97,034,000
The April 2019 Offering [Member]
Cash flows from financing activities:
Net proceeds from issuance of securities in underwritten offering		8,074,000
The September 2019 Offering [Member]
Cash flows from financing activities:
Net proceeds from issuance of securities in underwritten offering		$ 7,741,000