Convertible Note Payable

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Convertible Note Payable

Convertible Note Payable

In October 2012, in conjunction with our initial public offering the Post-IPO GSK Note was established in the principal amount of $5.4 million, with a maturity date of October 9, 2015. At December 31, 2014, the fair value of the Post-IPO GSK Note was $23.4 million and was classified as “Convertible note payable, at fair value” on the balance sheet. On January 29, 2015, the principal amount outstanding under the Post-IPO GSK Note of $5.4 million was converted into 1,356,738 shares of our common stock at a conversion price of $4.00 per share.