Summary of Significant Accounting Policies (Policy)

6 Months Ended

Jun. 30, 2013

Summary of Significant Accounting Policies [Abstract]

Basis of Presentation

The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. The balance sheet as of June 30, 2013, statements of operations and statements of comprehensive loss for the three and six months ended June 30, 2013 and 2012 and the statements of cash flows for the six months ended June 30, 2013 and 2012 are unaudited, but include all adjustments (consisting of normal recurring adjustments) that the Company considers necessary for a fair presentation of the financial position, operating results, comprehensive loss and cash flows, respectively, for the periods presented. Although the Company believes that the disclosures in these financial statements are adequate to make the information presented not misleading, certain information and footnote information normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to the rules and regulations of the United States Securities and Exchange Commission ("SEC").

Results for any interim period are not necessarily indicative of results for any future interim period or for the entire year. The accompanying unaudited financial statements should be read in conjunction with the financial statements and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2012.

Use of Estimates

Use of Estimates

The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from these estimates.

Fair Value Measurements

Fair Value Measurements

The Company applies Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurements and Disclosures, for financial and non-financial assets and liabilities.

ASC 820 discusses valuation techniques, such as the market approach (comparable market prices), the income approach (present value of future income or cash flow) and the cost approach (cost to replace the service capacity of an asset or replacement cost). The statement utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The following is a brief description of those three levels:

Level 1: Observable inputs such as quoted prices (unadjusted) in active markets for identical assets or liabilities.

Level 2: Inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3: Unobservable inputs that reflect the reporting entity's own assumptions.

Investments

Investments consist of commercial paper, corporate notes and an investment in one auction rate security. Classification of marketable securities between current and non-current is dependent upon the original maturity date at purchase. Those securities purchased with original maturities greater than 90 days, but less than one year are classified as current and those with greater than one year are classified as non-current.

Interest and dividend income is recorded when earned and included in interest income. Premiums and discounts, if any, on investments are amortized or accreted to maturity and included in interest income. The specific identification method is used in computing realized gains and losses on the sale of the Company's securities.

The Company has classified its investments as available-for-sale since the Company may need to liquidate these securities within the next year. The available-for-sale securities are carried at fair value and unrealized gains and losses on these securities, if determined to be temporary, are included in accumulated other comprehensive income (loss) in stockholders' equity. Investments are evaluated periodically to determine whether a decline in value is "other-than-temporary." The term "other-than-temporary" is not intended to indicate a permanent decline in value. Rather, it means that the prospects for a near term recovery of value are not necessarily favorable, or that there is a lack of evidence to support fair values equal to, or greater than, the carrying value of the security. Management reviews criteria, such as the magnitude and duration of the decline, as well as the Company's ability to hold the securities until market recovery, to predict whether the loss in value is other-than-temporary. If a decline in value is determined to be other-than-temporary, the value of the security is reduced and the impairment is recorded in the statement of operations.

Restricted Cash

The Company's restricted cash includes payments received under the PATH agreement (See Note 8) until such time as the Company has paid for the work performed for the related Phase 2 RSV clinical trial. In addition, the Company's non-current restricted cash with respect to its new manufacturing, laboratory and office space in Gaithersburg, Maryland functions as collateral for letters of credit, which serve as security deposits for the duration of the leases.

Net Loss per Share

Net Loss per Share

Net loss per share is computed using the weighted average number of shares of common stock outstanding. All outstanding warrants, stock options and unvested restricted stock awards totaling 15,832,208 shares and 13,110,708 shares at June 30, 2013 and 2012, respectively, are excluded from the computation, as their effect is antidilutive.

Reclassifications

Reclassifications

Within the June 30, 2012 statement of operations, certain overhead expenses relating to supply chain management of $0.4 million have been reclassified from general and administrative expenses to research and development expenses. Also, within the June 30, 2012 statement of cash flows, additional lease incentives received of $1.1 million recorded in the change in accounts payable and accrued expenses have been reclassified and are included in the change in lease incentives received. All of these reclassifications have been made to conform to current year presentation. In its Quarterly Report on Form 10-Q for the period ended March 31, 2013, the Company had recorded $0.2 million and reclassified $0.1 million of patent costs from general and administrative expenses to research and development expenses for the three months ended March 31, 2013 and 2012, respectively. The Company subsequently determined that patent costs should remain as a general and administrative expense and these costs have been shown as a general and administrative expense for all periods presented herein.

- Definition

Entity's cash and cash equivalents accounting policy with respect to restricted balances. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits.

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- Definition

Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.

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- Definition

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.

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