8. Loan and Security Agreements

Oxford Finance LLC

In December 2012, the Company entered into a Loan and Security Agreement (the "Oxford Loan") with Oxford Finance LLC ("Oxford") pursuant to which the Company borrowed a total of $15.0 million from Oxford. The Oxford Loan accrued interest at a fixed annual rate equal to 9.20% (Three-month U.S. Libor rate of 0.47% plus 8.73%).

Interest on the Oxford Loan was payable monthly and principal was due in 30 equal consecutive monthly installments beginning on February 1, 2015 and ending on July 1, 2017. In addition, the Company was required to make a final payment of $675,000 on the maturity date of the Oxford Loan (July 1, 2017).

In connection with the Oxford Loan, the Company issued Oxford warrants to purchase 62,505 shares of common stock at $6.00 per share. These warrants expire on December 14, 2019.

In February 2015, the Company terminated and repaid all amounts outstanding under the Oxford Loan and recorded a loss on the extinguishment of the Oxford Loan (see further discussion below).

Hercules Technology Growth Capital, Inc.

In February 2015, the Company entered into a loan and security agreement (the "Hercules Loan") with Hercules Technology Growth Capital, Inc. ("Hercules") for a term loan of up to $25.0 million. A first tranche of $16.5 million was funded upon execution of the Hercules Loan, approximately $15.5 million of which was used to repay the Company's existing term loan with Oxford. The Company is scheduled to make interest-only payments on the loan until July 1, 2016, which period may be extended under certain circumstances. Under the terms of the Hercules Loan, the Company may, but is not obligated to, draw an additional tranche of up to $8.5 million prior to July 1, 2016, subject to the achievement of certain clinical milestones, which may be extended to December 31, 2016 under certain circumstances.

The Hercules Loan accrues interest at a rate of the greater of 9.0% or 9.0% plus Prime minus 4.25% and is payable monthly. Principal is due in 30 equal consecutive monthly installments beginning on July 1, 2016 and ending on December 1, 2018. In addition, the Company is required to make a final payment of $610,500 on the maturity date of the Hercules Loan (December 1, 2018).

The Company may prepay all, but not less than all, of the Hercules Loan subject to a prepayment premium of 3.0% of the outstanding principal if prepaid during the first year, 2.0% of the outstanding principal if prepaid during the second year and 1.0% of the outstanding principal if prepaid after the second year. The obligations of the Company under the Hercules Loan are secured by a perfected first position lien on all of the assets of the Company, excluding intellectual property assets.

In connection with the Hercules Loan, the Company issued Hercules a warrant to purchase 180,274 shares of the Company's common stock at an exercise price of $5.89 per share which expires on February 24, 2020 and granted Hercules the right to participate in future equity financings in an amount up to $2.0 million while the loan and warrant are outstanding.

The Company allocated the proceeds of $16.5 million in accordance with ASC 470 based on the relative fair values. The relative fair value of the warrants of approximately $1.2 million at the time of issuance, which was determined using the Black-Scholes option-pricing model, was recorded as additional paid-in capital and reduced the carrying value of the debt. The significant assumptions used in preparing the option pricing model for valuing the Company's warrant issued to Hercules include (i) volatility (75.0%), (ii) risk free interest rate of 1.22% (estimated using treasury bonds with a 4 year life), (iii) strike price ($5.89) for the common stock warrant, (iv) fair value of common stock ($9.82) and (v) expected life (four years). The discount on the debt is being amortized to interest expense over the term of the debt.

As a result of the repayment of the Oxford Loan, the Company recorded a loss on the extinguishment of debt of approximately $1.0 million on the Company's statement of operations for the year ended December 31, 2015, representing a prepayment premium, the unamortized discount of the Oxford Loan and the write off of deferred financing costs.

Interest expense on the Oxford Loan and the Hercules Loan including the accretion of the value of the related warrants and amortization of the deferred financing costs was approximately $2,077, $1,545 and $1,472, for the years ended December 31, 2015, 2014 and 2013, respectively.

The annual maturities of the Hercules Loan, as of December 31, 2015, are as follows:

2016	$	2,999
2017		6,428
2018		7,073

Total	$	16,500