Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (32,938)	$ (17,209)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	121	203
Stock-based compensation expense	1,676	1,029
Amortization of convertible debt discount	1,057
Financing costs, derivative liability and warrants	997
Change in value of derivative liability	(386)
Changes in operating assets and liabilities:
Restricted cash		250
Receivables	(17)	908
Prepaid and other current assets	2,597	(2,427)
Other assets	81	2,875
Accounts payable	(1,078)	(917)
Accrued compensation	176	340
Current deferred revenue-related party		(790)
Accrued liabilities	(625)	2,133
Deferred rent	(37)	(60)
Deferred revenue-related party, non-current		(2,845)
Facility lease exit obligation	(104)	(193)
Net cash used in operating activities	(28,480)	(16,703)
Cash flows from investing activities:
Transfer to/from restricted cash, net	(1,006)
Capital expenditures	(75)
Net cash used in investing activities	(1,081)
Cash flows from financing activities:
Proceeds from issuance of convertible debt	3,050
Proceeds from issuance of convertible debt - related party	19,950
Proceeds from issuance of common stock	104	175
Payments for financing costs	(2,414)
Net cash provided by financing activities	20,690	175
Net decrease in cash and cash equivalents	(8,871)	(16,528)
Cash and cash equivalents at beginning of year	31,462	47,990
Cash and cash equivalents at end of year	22,591	$ 31,462
Supplemental disclosure of cash flow information:
Cash paid for interest	1,005
Non-cash disclosure of financing activities:
Reclassification of derivative liability to equity	8,362
Reclassification of warrants to equity	11
Debt discount from warrants	$ 662