6.	Long-term Debt

On June 28, 2013 we entered into the Loan Agreement with the Lenders, pursuant to which the Lenders funded an aggregate principal amount of $27.0 million (Term Loans), subject to the terms and conditions set forth in the loan agreement. The Term Loans accrue interest at a fixed rate of 9.75% per annum. Pursuant to the Loan Agreement, we are required to make interest only payments through July 1, 2014 and thereafter we are required to make payments of principal and accrued interest in equal monthly installments sufficient to amortize the Term Loans through July 1, 2017, the maturity date. All unpaid principal and interest with respect to the Term Loans is due and payable in full on July 1, 2017. At maturity of the Term Loans, or earlier repayment in full following voluntary prepayment or upon acceleration, the Company is required to make a final payment fee in an aggregate amount equal to $1,620,000. In connection with the Term Loans, on June 28, 2013, we issued to the Lenders warrants to purchase up to an aggregate of 596,553 shares of our common stock at an exercise price of $2.26 per share. These warrants are immediately exercisable and will expire on June 28, 2020.

In connection with the funding of the Loan Agreement, we prepaid all outstanding amounts under the prior loan agreement, at which time the Company’s obligations under the prior loan agreement immediately terminated. The Company paid to the prior agent and the prior lenders approximately $18,866,000, consisting of the then outstanding principal balance due of approximately $17,325,000, accrued but unpaid interest of approximately $119,000, a final payment fee (net of fees waived or refunded by the Lenders under the new loan agreement) of approximately $1,078,000, a prepayment fee (net of fees waived or refunded by the Lenders under the new loan agreement) of approximately $312,000 and other customary lender fees and expenses.

The net proceeds of the Term Loan, after payment of lender fees and expenses and prepaying all the outstanding amounts relating to the prior loan agreement, were approximately $7.8 million.

For the continuing Lenders, we accounted for this amendment as a debt modification. Accordingly, related fees of $1,942,000 were recorded as debt discount, and along with the unamortized debt discount will be amortized as an adjustment of interest expense using the effective interest method. For one existing lender that did not participate in the Term Loan, the payoff of their loan was accounted for as debt extinguishment. Accordingly, a loss on debt extinguishment of $708,000 was recorded, which includes that lender’s portion of unamortized fees and discounts along with prepayment and final payment fees.

We allocated the aggregate proceeds of the Term Loan between the warrants and the debt obligations based on their relative fair values. The fair value of the warrants issued to the Lenders was calculated utilizing the Black-Scholes option pricing model. We are amortizing the resulting additional discount of $949,000 to interest expense over the term of the loan using the effective interest method. The overall effective interest rate for the Term Loan is 13.92%. The Term Loan is collateralized by the tangible assets of the company, including a security interest in substantially all of its existing and after-acquired assets.

On September 19, 2014, we entered into a Letter Agreement with the Lenders waiving financial covenant compliance pursuant to the Loan Agreement through October 31, 2014. The Loan Agreement requires the Company to maintain certain minimum cash balances at all times during the term of the Loan Agreement. In exchange for the above waiver, the Company agreed to re-price all 596,553 outstanding warrants issued by the Company to Oxford Finance LLC and Silicon Valley Bank pursuant to the Loan Agreement, with an exercise price per share equal to the lower of (i) the closing price per share of the Company's common stock on September 30, 2014, or (ii) the average closing price per share of the Company's common stock for October 1, 2 and 3, 2014. Following the authoritative accounting guidance, warrants with variable exercise price features are accounted for as liabilities, with changes in the fair value included in operating expenses. The Company estimated the fair value of the warrants immediately before and after modification using an option pricing model to reclassify its fair value from additional paid-in capital to warrant liability and re-measured the warrant liability at September 30, 2014 with the change in fair value of $134,000 accounted for as operating expenses.

The following key assumptions were used by the Company to estimate the fair value of the warrant liability. Expected volatility was based primarily on historical volatility. Historical volatility was computed using daily pricing observations for recent periods that corresponded to the expected term of the warrants. We believe this method produced an estimate that was representative of our expectations of future volatility over the expected term of these warrants. The expected life was based on the remaining contractual term of the warrants. The risk-free interest rate was the interest rate for treasury constant maturity instruments published by the Federal Reserve Board that was closest to the expected term of the warrants.

On September 29, 2014 we entered into a 2^nd Amendment to the Loan Agreement with the Lenders in which we were provided a conditional waiver of principal payments subject to meeting certain capital raise requirements, which we achieved in October. The waiver of principal payments continues through April 1, 2015 and we are then required to make payments of principal and accrued interest in equal monthly installments sufficient to amortize the Term Loans through the maturity date.