Summary of Significant Accounting Policies

The Company’s significant accounting policies are described in Note 2 to its audited consolidated financial statements for the year ended December 31, 2015, which are included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 15, 2016. Except as discussed below, these accounting policies have not significantly changed during the three months ended March 31, 2016.

Fair Value Measurements

The carrying amount of financial instruments consisting of cash, restricted cash, trade accounts receivable, prepaid expenses and other current assets, accounts payable, accrued expenses, accrued compensation and current portion of long-term debt included in the Company’s consolidated financial statements are reasonable estimates of fair value due to their short maturities. Based on the borrowing rates currently available to the Company for loans with similar terms, management believes the fair value of long-term debt approximates its carrying value.

Authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:



Level 1:	Observable inputs such as quoted prices in active markets;
Level 2:	Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and
Level 3:	Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

The Company does not maintain any financial instruments that are considered to be Level 1 or Level 2 instruments as of March 31, 2016 or December 31, 2015. The Company classifies its common stock warrant liabilities within Level 3 of the fair value hierarchy because they are valued using valuation models with significant unobservable inputs. The following table provides a reconciliation of liabilities measured at fair value using significant unobservable inputs (Level 3) for the three months ended March 31, 2016 (in thousands):



	Common Stock Warrant Liabilities
Balance at December 31, 2015	$	687
Change in fair value	(114		)
Balance at March 31, 2016	$	573

Common stock warrant liabilities are measured at fair value using the Black-Scholes option pricing valuation model. The assumptions used in the Black-Scholes option pricing valuation model for the common stock warrant liabilities were: (a) a risk-free interest rate based on the rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the remaining contractual term of the warrants; (b) an assumed dividend yield of zero based on the Company’s expectation that it will not pay dividends in the foreseeable future; (c) an expected term based on the remaining contractual term of the warrants; and (d) an expected volatility based upon the Company's historical volatility over the remaining contractual term of the warrants. The significant unobservable input used in measuring the fair value of the common stock warrant liabilities associated with the Deerfield Facility Agreement (described in Note 5 below) is the expected volatility. Significant increases in volatility would result in a higher fair value measurement.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued new accounting guidance related to revenue recognition. This new standard replaces all current U.S. GAAP guidance on this topic and eliminates all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. This guidance, including all subsequent clarifications, is effective for the Company for annual and interim reporting periods in fiscal years beginning after December 15, 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. The Company is evaluating the impact of adopting this new accounting standard on its financial statements.

In August 2014, the FASB issued guidance related to disclosures of uncertainties about an entity’s ability to continue as a going concern. The guidance requires management to evaluate whether there are conditions and events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the financial statements are issued. Management will be required to make this evaluation for both annual and interim reporting periods and will have to make certain disclosures if it concludes that substantial doubt exists or when its plans alleviate substantial doubt about the entity’s ability to continue as a going concern. Substantial doubt exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued. The guidance is effective for annual periods ending after December 15, 2016 and for interim reporting periods thereafter. The Company is evaluating the impact of this guidance and expects to adopt the standard for the annual reporting period ending December 31, 2016.

In April 2015, the FASB issued guidance, which amends current presentation guidance by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Prior to the issuance this guidance, debt issuance costs were required to be presented as an asset in the balance sheet. The Company adopted the provisions of the new guidance during the interim period ended March 31, 2016 and prior period amounts have been reclassified to conform to the current period presentation. As of December 31, 2015, $0.4 million of debt issuance costs were reclassified in the consolidated balance sheet from prepaid expenses and other current assets to current portion of long-term debt. The adoption of ASU 2015-03 did not impact the Company's consolidated statement of operations, comprehensive loss or cash flows.

In July 2015, the FASB issued new accounting guidance, which changes the measurement principle for inventory from the lower of cost or market to lower of cost and net realizable value for entities that do not measure inventory using the last-in, first-out or retail inventory method. The guidance also eliminates the requirement for these entities to consider replacement cost or net realizable value less an approximately normal profit margin when measuring inventory. The guidance is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company is evaluating the impact of adopting this new accounting standard on its financial statements.

In February 2016, the FASB issued new accounting guidance, which changes several aspects of the accounting for leases, including the requirement that all leases with durations greater than twelve months be recognized on the balance sheet. The guidance is effective for annual periods and interim periods in fiscal years beginning after December 15, 2018. The Company is evaluating the impact of adopting this new accounting standard on its financial statements.

In March 2016, the FASB issued new accounting guidance, which changes several aspects of the accounting for share-based payment award transactions, including accounting and cash flow classification for excess tax benefits and deficiencies, forfeitures, and tax withholding requirements and cash flow classification. The guidance is effective for annual periods and interim periods in fiscal years beginning after December 15, 2016. The Company is evaluating the impact of adopting this new accounting standard on its financial statements.