Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net loss	$ (13,073)	$ (11,216)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	43	29
Non-cash interest expense (debt discount and deferred costs)	116	23
Change in fair value of warrants	104
Stock-based compensation expense	822	629
Changes in assets and liabilities:
Accounts receivable	(156)
Prepaid expenses and other current assets	(372)	(165)
Inventory	(30)	(274)
Deposits and other assets		78
Accounts payable	91	2,071
Accrued expenses and other current liabilities	656	1,331
Accrued interest	177	67
Deferred rent	6	(3)
Net cash used in operating activities	(11,616)	(7,430)
Cash flows from investing activities
Capital expenditures	(28)	(37)
Sale of marketable securities	5,291
Net cash provided by (used in) investing activities	5,263	(37)
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs		40,888
Proceeds from exercise of stock options	181	2
Proceeds from notes payable, net of costs	5,000	2,500
Repayments of notes payable		(2,500)
Financing costs and discount of notes payable	(104)
Net cash provided by financing activities	5,077	40,890
Net (decrease) increase in cash and cash equivalents	(1,276)	33,423
Cash and cash equivalents, at beginning of period	13,047	3,939
Cash and cash equivalents, at end of period	11,771	37,362
Supplemental disclosure of cash flow information
Cash paid during the period for interest	$ 368	$ 174