Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Company’s functional currency is the U.S. dollar. Unaudited Interim Financial Information The accompanying financial statements are unaudited. The interim unaudited financial statements have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s balance sheet as of June 30, 2016, its results of operations and its comprehensive income (loss) for the three and six months ended June 30, 2016 and 2015, its statement of stockholders’ equity for the period from January 1, 2016 to June 30, 2016 and its cash flows for the six months ended June 30, 2016 and 2015. The financial data and other information disclosed in these notes related to the three and six months ended June 30, 2016 and 2015 are not necessarily indicative of the results to be expected for the year ending December 31, 2016, any other interim periods or any future year or period. Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 of the Notes to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. Since the date of those financial statements, there have been no changes to the Company’s significant accounting policies. Use of Estimates Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these financial statements, management used significant estimates in the following areas, among others: stock-based compensation expense, the determination of the fair value of stock-based awards, the fair value of liability-classified common stock warrants, and the accounting for research and development costs, accrued expenses and the recoverability of the Company’s net deferred tax assets and related valuation allowance. Cash, Cash Equivalents, Investments and Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents, marketable securities and restricted cash. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents are valued at cost, which approximates their fair market value. The Company maintains a portion of its cash and cash equivalent balances in money market mutual funds that invest substantially all of their assets in U.S. government agency securities, U.S. Treasury securities and reverse repurchase agreements (“RRAs”). RRAs are collateralized by deposits in the form of ‘Government Securities and Obligations’ for an amount not less than 102% of their value. The Company does not record an asset or liability related to the collateral, as the Company is not permitted to sell or repledge the associated collateral. The Company maintains its marketable securities balances in the form of U.S. Treasury and U.S. government agency securities. The Company classifies its marketable securities as “available-for-sale”, pursuant to ASC Topic 320, Investments—Debt and Equity Securities, carries them at fair market value and classifies them as current assets on its balance sheets. Unrealized gains and losses on marketable securities are recorded as a separate component of accumulated other comprehensive income (loss) included in stockholders’ equity. As of June 30, 2016 and December 31, 2015, the Company had $107.7 million and $125.9 million, respectively, in available-for-sale investments, all classified as current assets. See Note 3 for additional information. The fair value of the Company’s investments is determined based on observable market quotes or valuation models using assessments of counterparty credit worthiness, credit default risk of underlying security and overall capital market liquidity. The Company reviews unrealized losses associated with available-for-sale securities to determine the classification as “temporary” or “other-than-temporary” impairment. A temporary impairment results in an unrealized loss being recorded in other comprehensive income (loss). If a decline in the fair value is considered other-than-temporary, based on available evidence, the unrealized loss is transferred from other comprehensive income (loss) to the statement of operations. The Company considers various factors in determining the classification, including the length of time and extent to which the fair value has been less than the Company’s cost basis, the financial condition and near-term prospects of the issuer or investee, and the Company’s ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. There were no charges taken for other-than-temporary declines in fair value of short-term or long-term investments during the three and six months ended June 30, 2016. The Company recorded unrealized gains of $44,979 and $2,127 during the three months ended June 30, 2016 and 2015, respectively, and $280,973 and $28,884 during the six months ended June 30, 2016 and 2015, respectively. Realized gains (losses) are included in interest income (expense) in the statement of operations and comprehensive income (loss) on a specific identification basis. The Company did not record any realized gains or losses during the six months ended June 30, 2016 and 2015. The Company maintains a letter of credit totaling $112,000 as collateral for the Company’s facility lease obligations in Pennsylvania and has recorded this and accumulated interest thereon as restricted cash on its balance sheet. Fair Value of Financial Instruments The carrying amount of the Company’s financial instruments, which include cash and cash equivalents, marketable securities, restricted cash, accounts payable and accrued expenses approximate their fair values, given their short-term nature. The carrying amount of the Company’s loans payable at June 30, 2016 and December 31, 2015 is the nominal value of the loan payable, which is the carrying value, exclusive of debt discount and deferred charges. This approximates fair value because the interest rate is reflective of the rate the Company could obtain on debt with similar terms and conditions. Certain of the Company’s common stock warrants are carried at fair value, as disclosed below. The Company has evaluated the estimated fair value of financial instruments using available market information and management’s estimates. The use of different market assumptions and/or estimation methodologies could have a significant effect on the estimated fair value amounts. See Note 3 for additional information. Recent Accounting Pronouncements In March 2016, the FASB issued Accounting Standards Update 2016-09, Compensation— Stock Compensation (“ASU 2016-09”). ASU 2016-09 was issued as part of the FASB Simplification Initiative. This update addresses the income tax effects of stock-based payments and eliminates the windfall pool concept, as all of the tax effects related to stock-based payments will now be recorded at settlement (or expiration) through the income statement. The new guidance also permits entities to make an accounting policy election for the impact of forfeitures on the recognition of expense for stock-based payment awards. Forfeitures can be estimated or recognized when they occur. The standard is effective for annual periods beginning after December 15, 2016 and interim periods within that reporting period. Early adoption is permitted in any interim or annual period, with any adjustment reflected as of the beginning of the fiscal year of adoption. The Company is evaluating the effect this standard will have on its financial statements and related disclosures. In February 2016, the FASB issued Accounting Standards Update 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires lessees to record most leases on their balance sheets and disclose key information about leasing arrangements in an effort to increase transparency and comparability among organizations. The standard is effective for annual periods beginning after December 15, 2018 and interim periods within that reporting period. Early adoption is permitted. The Company is evaluating the effect this standard will have on its financial statements and related disclosures. In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer in an amount reflecting the consideration it expects to receive in exchange for those goods or services. Additionally, in March 2016, the FASB issued Accounting Standards Update 2016-08 Revenue from Contracts with Customers, Principal versus Agent Considerations (“ASU 2016-08”). ASU 2016-08 amends the principal versus agent guidance in ASU 2014-09 to clarify how an entity should identify the unit of accounting for the principal versus agent evaluation and how it should apply the control principal to certain types of arrangements. The effective date for both standards is January 1, 2018, with an option that permits companies to adopt the standard as early as the January 1, 2017. Early application prior to the January 1, 2017 is not permitted. The standards permit the use of either the retrospective or cumulative effect transition method. The Company is evaluating the transition method that they will elect. The adoption of these standards is not expected to have a material impact on the Company’s financial statements. In August 2014, the FASB issued Accounting Standards Update 2014 ‑15, Presentation of Financial Statements ‑Going Concern (Subtopic 205 ‑40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which defines management’s responsibility to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures if there is substantial doubt about its ability to continue as a going concern. The pronouncement is effective for annual reporting periods ending after December 15, 2016 with early adoption permitted. The adoption of this guidance is not expected to have a material impact on the Company’s financial statements . |