CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (6,480,000)	$ (3,963,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	49,000	49,000
Stock-based compensation expense	326,000	401,000
Change in fair value of warrant liability	0	0
Gain from change in fair value of contingent consideration	(1,000,000)	(1,200,000)
Gain on sale of equipment	0	(5,000)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,912,000)	(236,000)
Accounts payable	316,000	486,000
Accrued expenses and other liabilities	709,000	85,000
Net cash used in operating activities	(7,992,000)	(4,383,000)
Investing activities
Sales of equipment	0	5,000
Net cash provided by investing activities	0	5,000
Financing activities
Proceeds from issuance of common stock and the issuance and exercise of common stock warrants, net of issuance costs	0	9,376,000
Proceeds from sale of common stock pursuant to 2014 ESPP	7,000	10,000
Net cash provided by financing activities	7,000	9,386,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(7,985,000)	5,008,000
Cash, cash equivalents and restricted cash at beginning of period	50,442,000	14,690,000
Cash, cash equivalents and restricted cash at end of period	42,457,000	19,698,000
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for new operating lease	236,480,000	0
Cash paid for amounts included in the measurement of liabilities	$ 38,202,000	$ 0