Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (1,297)	$ (1,339)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	580	1,100
Stock-based compensation	96	164
Non-cash interest expense		35
Non-cash interest expense related to sale of future royalties	491	544
Non-cash revenue related to sale of future royalties	(2,769)	(1,384)
Change in operating assets and liabilities:
Accounts receivable	956	(3,788)
Prepaid expenses and other assets	(690)	100
Accounts payable	(55)	(184)
Other accrued liabilities	(520)	99
Net cash used in operating activities	(3,208)	(4,653)
Cash flows from investing activities:
Purchase of property and equipment	(4)	(552)
Proceeds from sale of equipment	3
Net cash used in investing activities	(1)	(552)
Cash flows from financing activities:
Net proceeds from issuance of securities in registered direct offering	9,175	2,540
Proceeds from issuance of common stock upon exercise of common stock warrants	10,349
Proceeds from issuance of common stock upon exercise of stock options	18
Repayment of principal on secured promissory note payable to Oxford Finance		(417)
Net cash provided by financing activities	19,542	2,123
Net increase (decrease) in cash and cash equivalents	16,333	(3,082)
Cash, cash equivalents and restricted cash at beginning of the period	13,526	11,506
Cash, cash equivalents and restricted cash at end of the period	29,859	8,424
Supplemental disclosure of cash flow information:
Interest paid		72
Supplemental disclosure of non-cash financing activity:
Issuance of warrants to placement agent’s representatives	453	100
Acquisition of property and equipment included in accounts payable		$ 123