Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating activities
Net loss	$ (171,358,000)	$ (58,154,000)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	1,268,000	439,000
Remeasurement of contingent consideration	4,414,000	2,740,000
Remeasurement of convertible preferred stock warrants		15,373,000
Preferred stock issued in exchange for services		147,000
Non-cash interest (income) expense and amortization of (receivable) debt discount	(38,000)	3,897,000
Impairment of property and equipment	128,000
Gain on extinguishment of 2013 Notes		(2,048,000)
Stock-based compensation expense	11,547,000	7,236,000
Changes in operating assets and liabilities:
Receivables from collaboration and license agreement	1,877,000
Receivables from related party		278,000
Notes receivable from related parties		107,000
Notes receivable	1,853,000
Prepaid assets	(11,194,000)	(12,157,000)
Other assets	(2,331,000)
Other assets - related party	1,691,000
Other assets - non-current	42,000	(476,000)
Accounts payable	19,100,000	552,000
Accounts payable - related parties	1,072,000	4,580,000
Accrued and other liabilities	13,771,000	498,000
Deferred revenue	(383,000)	25,885,000
Advance payments under license agreements	(1,192,000)
Contingent liability to collaborator	15,850,000	20,150,000
Other liabilities, non-current	326,000	311,000
Net cash (used in) provided by operating activities	(113,557,000)	9,358,000
Investing activities
Net cash acquired from acquisition of InteKrin Therapeutics, Inc.		2,334,000
Purchases of property and equipment	(4,720,000)	(2,360,000)
Increase in restricted cash	(785,000)
Net cash used in investing activities	(5,505,000)	(26,000)
Financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs		54,660,000
Proceeds from issuance of convertible preferred stock upon exercise of warrants		74,000
Proceeds from follow-on offering, net of underwriters discounts and commissions	112,800,000
Proceeds from private placement	10,000,000
Proceeds from issuance of common stock upon exercise of stock options	1,015,000	19,000
Repurchase of restricted common stock		(2,000)
Net cash provided by financing activities	122,359,000	52,190,000
Effect of exchange rate changes in cash and cash equivalents	2,000	(201,000)
Net increase in cash and cash equivalents	3,299,000	61,321,000
Cash and cash equivalents at beginning of period	150,392,000	39,554,000
Cash and cash equivalents at end of period	153,691,000	100,875,000
Initial Public Offering
Financing activities
Payments of offering costs	(855,000)	$ (2,561,000)
Follow-On Public Offering
Financing activities
Payments of offering costs	$ (601,000)