Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities:
Net Loss	$ (10,229)	$ (18,304)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,708	2,906
Warrant issued to consultant	9	0
Change in fair value of warrant liabilities	(4,064)	(2,157)
Depreciation	207	172
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	268	1,251
Accounts payable	(1,141)	(895)
Accrued expenses	(41)	(557)
Accrued employee benefits	(640)	1,293
Deferred rent	(66)	19
Net Cash Used In Operating Activities	(13,989)	(16,272)
Cash Flows From Investing Activities:
Purchases of property and equipment	0	(209)
Net Cash Used In Investing Activities	0	(209)
Cash Flows From Financing Activities:
Proceeds from sale of Series A Preferred Stock, net of issuance cost	0	11,952
Proceeds from issuance of common stock for stock option exercises	0	166
Proceeds from "at the market" stock issuance	6,422	6,358
Net Cash Provided By Financing Activities	6,422	18,476
Net (decrease) increase in cash	(7,567)	1,995
Cash at beginning of period	17,116	19,055
Cash at end of period	9,549	21,050
NONCASH FINANCING ACTIVITY:
Dividends on redeemable convertible preferred stock	$ 181	$ 0