Unaudited Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities
Net loss	$ (33,964)	$ (21,463)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	107	90
Non-cash interest expense (debt discount and deferred costs)	87	53
Change in fair value of derivatives	304
Stock-based compensation expense	1,780	786
Changes in assets and liabilities:
Prepaid expenses and other current assets	432	317
Inventory	(329)
Deposits and other assets	68	(4)
Accounts payable	4,095	1,118
Accrued expenses and other current liabilities	(195)	1,614
Accrued interest	(200)	260
Deferred rent	18	1
Net cash used in operating activities	(27,797)	(17,228)
Cash flows from investing activities
Capital expenditures	(452)	(123)
Purchase of marketable securities	(9,176)
Net cash used in investing activities	(9,628)	(123)
Cash flows from financing activities
Sale of Series E convertible preferred stock, net of costs		10,642
Proceeds from issuance of common stock, net of issuance costs	45,737
Proceeds from exercise of stock options	65	20
Proceeds from notes payable	17,500
Repayments of notes payable	(12,500)
Deferred financing costs and discount of notes payable	(820)
Net cash provided by financing activities	49,982	10,662
Net increase (decrease) in cash and cash equivalents	12,557	(6,689)
Cash and cash equivalents, at beginning of period	3,939	18,923
Cash and cash equivalents, at end of period	$ 16,496	$ 12,234