4. Long-Term Debt, Commitments and Contingencies

Long-Term Debt

Long-term debt and unamortized discount balances (excluding convertible debt) are as follows (in thousands):

	September 30, 2013			December 31, 2012

Long-term debt	$	2,250		$	3,750
Less debt discount, net of current portion	—			(18		)
Long-term debt, net of debt discount	2,250			3,732
Less current portion of long-term debt	(2,000		)	(2,000		)
Long-term debt, net of current portion	$	250		$	1,732

Current portion of long-term debt	$	2,000		$	2,000
Current portion of debt discount	(29		)	(59		)
Current portion of long-term debt, net	$	1,971		$	1,941

June and July 2013 Convertible Note Financing

In June and July 2013, the Company issued convertible promissory notes in an aggregate principal amount of $3.7 million to certain existing stockholders. The notes accrue interest at 2% per year and are due on June 24, 2014, if not earlier repaid or converted in full. In connection with the issuance of the convertible notes, the Company recorded a debt discount of $0.3 million related to a beneficial conversion feature that was recorded as a result of the gross fair value of the shares of Series C convertible preferred stock into which the debt could convert being greater than the proceeds allocated to the debt instrument. The debt discount is amortized as interest expense utilizing the effective interest method over the one year term of the debt. During the three and nine months ended September 30, 2013, the Company recorded debt discount amortization of $0.1 million. As of September 30, 2013, an aggregate of $3.7 million of principal, $0.3 million of unamortized debt discount and $0.1 million of accrued interest were outstanding under the promissory notes. The notes converted into common stock in connection with the Company’s IPO in October 2013 (see Note 6).

August 2013 Convertible Note Financing

In August 2013, the Company issued convertible promissory notes in an aggregate principal amount of $20.0 million to certain new investors. The notes accrue interest at 2% per year and are due on August 8, 2016, if not earlier repaid or converted in full. As of September 30, 2013, an aggregate of $20.0 million of principal and $0.1 million of accrued interest were outstanding under the promissory notes. A portion of the notes were repaid in cash and the balance of the notes converted into common stock in connection with the Company’s IPO in October 2013 (see Note 6).

Facility Lease

On September 26, 2013, the Company exercised its option to extend for two years the lease on its office and laboratory space in San Diego, California until June 2016. As a result of the lease extension, the Company added an additional $0.5 million, $0.9 million and $0.5 million, respectively, of non-cancelable operating lease commitments for the years ending December 31, 2014, 2015 and 2016.