Condensed Statements of Cash Flows - USD ($) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating activities
Net loss	$ (40,230)	$ (13,686)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	89	21
Stock-based compensation	1,474	528
Loss on disposal of assets		3
Amortization of debt discount	422	834
Change in fair value of preferred stock warrant liabilities	(1,939)	(1,408)
Noncash interest expense on convertible notes	1,068	1,740
Amortization of beneficial conversion feature	429	895
Amortization of debt issuance costs	66	14
Deferred income taxes	(4,392)
Impairment of intangible assets	17,315
Change in assets and liabilities:
Prepaid expenses and other assets	302	(761)
Restricted cash		(334)
Accounts payable and accrued expenses	232	1,428
Deferred rent	(33)	26
Net cash used in operating activities	(25,197)	(10,700)
Investing activities
Cash received from merger transaction	33,232
Purchase of property and equipment	(31)	(130)
Net cash provided by (used in) investing activities	33,201	(130)
Financing activities
Proceeds from issuance of common stock, net	41,504
Proceeds from borrowings — term loans, net		14,822
Proceeds from convertible notes, net	12,954	7,984
Payments on term loan		(1,833)
Payments on capital lease obligations	(16)
Costs paid in connection with preparations for initial public offering		(2,423)
Net cash provided by financing activities	54,442	18,550
Net increase in cash and cash equivalents	62,446	7,720
Cash and cash equivalents at beginning of period	6,178	4,088
Cash and cash equivalents at end of period	68,624	11,808
Supplemental disclosure of cash flow information
Cash paid for interest	786	223
Noncash activities:
Conversion of promissory notes and interest to common stock	48,221
Financing costs in accounts payable and accrued expenses	130
Beneficial conversion feature related to promissory notes	396
Reclassification of preferred stock warrant liability to additional paid-in capital	521
Issuance of warrants — term loan and convertible notes, related party		868
Reclassification of stock award liability from equity upon modification		399
Accrued deferred initial public offering costs		1,147
Landlord paid leasehold improvements		259
Equipment purchased under capital lease		70
Accrued debt issuance costs		$ 25
Fair value of assets acquired and liabilities assumed in the Merger:
Fair value of assets acquired	18,723
Fair value of liabilities assumed	(5,832)
Fair value of net assets acquired in the Merger	$ 12,891
Financial Advisors [Member]
Noncash activities:
Issuance of common stock	852
Series A and B Preferred Stock [Member]
Noncash activities:
Conversion of preferred stock to common stock	$ 61,982
Series F Preferred Stock [Member]
Noncash activities:
Conversion of preferred stock to common stock	$ 24,832