2. Significant Accounting Policies

In addition to the policies described in Note 2 to the consolidated financial statements included in our 2012 Annual Report on Form 10-K, we apply the following significant accounting policies:

Basis of Presentation

Our interim Consolidated Financial Statements included in this report have been prepared in accordance with applicable presentation requirements, and accordingly do not include all information and disclosures necessary for a presentation of our financial position, results of operations and cash flows in conformity with accounting principles generally accepted in the United States of America ("GAAP"). In the opinion of management, these financial statements reflect all adjustments, consisting primarily of normal recurring accruals necessary for a fair statement of results for the periods presented. The results of operations for interim periods are not necessarily indicative of the results for the full year. Our interim financial statements should be read in conjunction with the financial statements and notes thereto contained in our 2012 Annual Report on Form 10-K. The year-end consolidated balance sheet data in these financial statements were derived from audited financial statements, but do not include all disclosures required by GAAP.

Use of Estimates

Significant estimates include useful lives of fixed assets, the periods over which certain revenues and expenses will be recognized, including collaboration revenue recognized from non-refundable up-front licensing payments and expense recognition of certain clinical trial costs which are included in research and development expenses, the amount of non-cash compensation costs related to share-based payments to employees and non-employees and the periods over which those costs are expensed, the likelihood of realization of deferred tax assets and the assumptions used in the valuations of in-process research and development, goodwill and contingent consideration liability.

In-Process Research and Development

The fair values of in-process research and development (IPR&D) acquired in business combinations are capitalized. The Company utilizes the "income method," which applies a probability weighting that considers the risk of development and commercialization to the estimated future net cash flows that are derived from projected sales revenues and estimated costs. These projections are based on factors such as relevant market size, patent protection, historical pricing of similar products and expected industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. This analysis is performed for each project independently. These assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are amortized over the remaining useful life or written off, as appropriate. IPR&D intangible assets which are determined to have a decline in their fair value are adjusted downward and an expense is recognized in the Consolidated Statements of Operations. These are tested at least annually or when a triggering event occurs that could indicate a potential impairment.

Goodwill

Goodwill represents excess consideration in a business combination over the fair value of identifiable net assets acquired. Goodwill is not amortized, but is subject to impairment testing at least annually or when a triggering event occurs that could indicate a potential impairment. The Company determines whether goodwill may be impaired by comparing the carrying value of its reporting unit to the fair value of its reporting unit.

Fair Value Measurements

In accordance with ASC 820 Fair Value Measurements and Disclosures, we use a three-level hierarchy for fair value measurements of certain assets and liabilities for financial reporting purposes that distinguishes between market participant assumptions developed from market data obtained from outside sources (observable inputs) and our own assumptions about market participant assumptions developed from the best information available to us in the circumstances (unobservable inputs). We assign hierarchy levels to assets constituting our available-for-sale portfolio and to our contingent consideration liability arising from the MIP acquisition based on our assessment of the transparency and reliability of the inputs used in the valuation. ASC 820 defines the three hierarchy levels as:

·	Level 1 - Valuations based on unadjusted quoted market prices in active markets for identical securities.

·	Level 2 - Valuations based on observable inputs other than Level 1 prices, such as quoted prices for similar assets at the measurement date, quoted prices in markets that are not active or other inputs that are observable, either directly or indirectly.

·	Level 3 - Valuations based on unobservable inputs that are significant to the overall fair value measurement, which as noted above involve management judgment.

Recurring Fair Value Measurements

We believe the carrying amounts of the Company's cash equivalents approximated their fair values as of September 30, 2013 and December 31, 2012 due to their short-term nature; we consider them Level 1 instruments. We also believe that the carrying values of accounts receivable, other current assets, other assets (restricted cash providing collateral for a letter of credit securing lease obligations) and accounts payable and accrued expenses approximate their fair values at those dates due to their short-term nature.

We believe the carrying amount of the contingent consideration liability arising from the MIP acquisition (see Note 3), which, as displayed in Note 6, we categorize as a Level 3 instrument, approximated its fair value (estimated as described in Note 3) as of September 30, 2013. The Company reviews the fair value of contingent consideration quarterly or whenever events or changes in circumstances occur that indicate there has been a change in the fair value.

Nonrecurring Fair Value Measurements

The Company's non-financial assets, such as intangible assets and property and equipment, are measured and recorded at fair value on the acquisition date, and if indicators of impairment exist, we assess recoverability by measuring the amount of any impairment by comparing the carrying value of the asset to its then-current estimated fair value (for intangible assets) or to market prices for similar assets (for property and equipment). If the carrying value is not recoverable we record an impairment charge. In connection with the second quarter amendment of the Company's Tarrytown lease, we recognized impairment losses of $347 on leasehold improvements and machinery and equipment removed from service which are included in Research and development expenses in our accompanying Consolidated Statements of Operation for the nine months ended September 30, 2013.