2. Summary of Significant Accounting Policies

        Initial and Additional Public Offering—On June 11, 2014, the Company completed its initial public offering whereby the Company sold 6,500,000 shares of common stock at a price of $8.00 per share. The shares began trading on the NASDAQ Global Market on June 6, 2014. In connection with the offering, all outstanding shares of our convertible preferred stock converted into 19,465,132 shares of common stock and 2,862,654 shares of common stock were issued in satisfaction of accumulated dividends accrued on the preferred stock. In addition, all outstanding warrants to purchase shares of A-1 convertible preferred stock and warrants to purchase shares of series B-2 convertible preferred stock were converted into the right to purchase 149,452 shares of common stock and the Company's warrant liability was reclassified to equity.

        On June 18, 2014 and June 25, 2014, the underwriters purchased an additional 512,744 shares in the aggregate by exercising a portion of the over-allotment option granted to them in connection with the initial public offering. As a result of the closing of the initial public offering and subsequent exercise of the over-allotment option, the Company received aggregate proceeds, net of underwriting discounts, commissions and offering costs, of approximately $50.4 million.

        In connection with the completion of its initial public offering, the Company filed an amended and restated certificate of incorporation, which, among other things, changed the number of authorized shares of common stock to 200,000,000 shares.

        On October 7, 2014, the Company completed an additional public offering whereby it sold 2,750,000 shares of common stock at a price of $18.25 per share, for aggregate proceeds, net of underwriting discounts, commissions and offering costs, of approximately $46.9 million. On October 7, 2014, the underwriters purchased an additional 378,524 shares in the aggregate by exercising a portion of the over-allotment option granted to them in connection with the offering. As a result of the public offering and subsequent exercise of the over-allotment option, the Company received aggregate proceeds, net of underwriting discounts, commissions and offering costs of approximately $53.4 million.

        Reverse Stock Split—On April 24, 2014, the Company effected a reverse stock split of the Company's common stock. The number of authorized shares of the Company's common stock and the par value did not change. Pursuant to the stock split, every 2.28 shares of the Company's issued and outstanding common stock were automatically combined into one issued and outstanding share of the Company's common stock. All shares and per share amounts in the financial statements and accompanying notes have been retroactively adjusted to give effect to the reverse stock split.

        Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States ("GAAP") requires the Company's management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure. Subsequent events have been evaluated up to the date of issuance of these financial statements.

        Cash Equivalents—The Company considers all highly liquid investment instruments with an original maturity when purchased of three months or less to be cash equivalents. Cash equivalents at December 31, 2014 and 2013 are primarily comprised of money market funds.

        Marketable Securities—All investment instruments with an original maturity date, when purchased, in excess of three months have been classified as current marketable securities. The Company classifies securities that are available to fund current operations as current assets. These marketable securities are classified as available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are included within other comprehensive (loss) income within stockholders' equity (deficit). The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest income. Realized gains and losses on available-for-sale securities are included in interest income. The cost of securities sold is based on the specific identification method. The Company periodically reviews the portfolio of securities to determine whether an other-than-temporary impairment has occurred. No such losses have occurred to date. There were no realized gains or losses on the sale of securities for the years ended December 31, 2014 and 2013.

        Fair Value Measurements—The Company determines the fair market values of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The following are three levels of inputs that may be used to measure fair value:

                                                                                                                                                                                    

        Concentrations of Credit Risk and Off-Balance-Sheet Risk—Financial instruments that potentially subject the Company to credit risk primarily consist of cash and cash equivalents and available-for-sale marketable securities. The Company mitigates its risk with respect to cash and cash equivalents and marketable securities by maintaining its deposits and investments at high-quality financial institutions. The Company invests any excess cash in money market funds and other securities, and the management of these investments is not discretionary on the part of the financial institution. The Company's credit exposure on its marketable securities is limited by its diversification among United States government and agency debt securities. The Company has no significant off-balance-sheet risks such as foreign exchange contracts, option contracts, or other hedging arrangements.

        Property and Equipment—Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the respective assets.

        Research and Development Costs—The Company accounts for research and development costs by expensing such costs to operations as incurred. Research and development costs primarily consist of clinical testing costs, including payments in cash and stock made to contract research organizations, personnel costs, outsourced research activities, laboratory supplies, and license fees.

        Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.

        Licensing Agreements—Costs associated with licensing early stage technology are expensed as incurred, and are included in research and development expenses.

        Impairment of Long-Lived Assets—The Company evaluates long-lived assets for potential impairment when there is evidence that events or changes in circumstances have occurred that indicate that the carrying amount of a long-lived asset may not be recovered. Recoverability of these assets is assessed based on the undiscounted expected future cash flows from the assets, considering a number of factors, including past operating results, budgets and economic projections, market trends, and product development cycles. Impairment in the carrying value of each asset is assessed when the undiscounted expected future cash flows derived from the asset are less than its carrying value.

        An impairment loss would be recognized in an amount equal to the excess of the carrying amount over the undiscounted expected future cash flows. No impairment charges have been recognized since the Company's inception.

        Segment Information—Operating segments are defined as components of an enterprise engaged in business activities for which discrete financial information is available and regularly reviewed by the chief decision maker in determining how to allocate resources and in assessing performance. The Company views its operations and manages its business as one operating segment and operates in one geographic area.

        Income Taxes—The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, as well as operating loss and tax credit carry forwards. The Company measures deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect on deferred tax assets and liabilities as a result of a change in tax rates is recognized as income in the period that includes the enactment date.

        The Company uses judgment to determine the recognition threshold and measurement attribute for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Any material interest and penalties related to unrecognized tax benefits are recognized in income tax expense.

        Due to uncertainty surrounding the realization of the favorable tax attributes in future tax returns the Company has recorded a full valuation allowance against otherwise realizable net deferred tax assets as of December 31, 2014 and 2013.

        Financial Instruments Indexed to and Potentially Settled in the Company's Common Stock —The Company evaluates all financial instruments issued in connection with its debt borrowings and equity offerings when determining the proper accounting treatment for such instruments in the Company's financial statements. The Company considers a number of generally accepted accounting principles to determine such treatment and evaluates the features of the instrument to determine the appropriate accounting treatment. The Company utilizes the Black-Scholes method or other appropriate methods to determine the fair value of its derivative financial instruments. Key valuation factors in determining the fair value include, but are not limited to, the current stock price as of the date of measurement, the exercise price, the remaining contractual life, expected volatility for the instrument and the risk-free interest rate. For financial instruments that are determined to be classified as liabilities on the balance sheet, changes in fair value are recorded as a gain or loss in the Company's statement of operations, with the corresponding amount recorded as an adjustment to the liability on its balance sheet.

        Stock-Based Compensation—The Company measures stock-based compensation cost at the accounting measurement date based on the fair value of the option, and recognizes the expense related to awards to employees on a straight-line basis over the requisite service period of the option, which is typically the vesting period. The Company estimates the fair value of each option using a Black-Scholes option pricing model that takes into account the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of the Company's common stock, expected dividends on the Company's common stock, and the risk-free interest rate over the expected life of the option. Due to the limited trading history of the Company's common stock since its June 2014 initial public offering, the Company uses the simplified method described in the SEC's Staff Accounting Bulletin No. 107, Share-Based Payment, to determine the expected life of the option grants. The Company's estimate of expected volatility is based on a review of the historical volatility of similar publicly held companies in the biotechnology field over a period commensurate with the option's expected term. The Company has never declared or paid any cash dividends on its common stock and does not expect to do so in the foreseeable future. Accordingly, the Company utilizes an expected dividend yield of zero. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant valuation for a period commensurate with the option's expected term. These assumptions are highly subjective and changes in them could significantly impact the value of the option and hence the related compensation expense.

        The Company applies an estimated forfeiture rate to current period expense to recognize compensation expense only for those awards expected to vest. Estimated forfeitures are based upon historical data, adjusted for known trends, and will be adjusted if actual forfeitures differ or are expected to differ from such estimates. Subsequent changes in estimated forfeitures are recognized through a cumulative adjustment in the period of change and also will impact the amount of stock-based compensation expense in future periods.

        Stock-based compensation expense for options granted to consultants is also determined based upon the fair value of the options issued, as determined by the Black-Scholes option pricing model and recognized on an accelerated basis. However, the unvested portion of such option grants is re-measured at each reporting period, until such time as the award is fully vested.

        Net Loss Per Common Share—Net loss per common share is calculated using the two-class method, which is an earnings allocation formula that determines net loss per share for the holders of the Company's common shares and participating securities. Prior to the initial public offering, all of the Company's series of preferred stock contained participation rights in any dividend paid by the Company and were deemed to be participating securities. Net income available to common shareholders and participating preferred shares was allocated to each share on an as-converted basis as if all of the earnings for the period had been distributed. The participating securities do not include a contractual obligation to share in losses of the Company and are not included in the calculation of net loss per share in the periods that have a net loss.

        Diluted net income per share is computed using the more dilutive of (a) the two-class method, or (b) the if-converted method. Prior to the initial public offering, the Company allocated net income first to preferred stockholders based on dividend rights and then to common and preferred stockholders based on ownership interests. The weighted-average number of common shares outstanding gives effect to all potentially dilutive common equivalent shares, including outstanding stock options, warrants, and, prior to the Company's initial public offering, potential issuance of stock upon the issuance of the Company's series A-6 convertible preferred stock ("Series A-6") as settlement of the liability to Nordic Bioscience ("Nordic"). Common equivalent shares are excluded from the computation of diluted net income per share if their effect is anti-dilutive.

        Comprehensive (Loss) Income—Comprehensive (loss) income refers to revenues, expenses, gains and losses that are excluded from net income, as these amounts are recorded directly as an adjustment to stockholders' deficit, net of tax. The Company's other comprehensive (loss) income is comprised of unrealized gains (losses) on its available-for-sale securities.

        Recently Adopted Accounting Standards—In July 2013, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists ("ASU 2013-11"). ASU 2013-11 clarifies guidance and eliminates diversity in practice on the presentation of unrecognized tax benefits when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists at the reporting date. The amendments under ASU 2013-11 are effective for interim and annual fiscal periods beginning after December 15, 2013, with early adoption permitted. The adoption of ASU 2013-11 did not have a material impact on the Company's results of operations, financial position, or cash flows.

        In December 2013, the FASB issued Accounting Standards Update No. 2013-12, Definition of a Public Business Entity ("ASU 2013-12"). ASU 2013-12 amends the Master Glossary of the FASB Accounting Standards Codification to include one definition of public business entity for future use in GAAP. ASU 2013-12 does not affect existing requirements but will be used in considering the scope of new financial guidance and will identify whether the guidance does or does not apply to public business entities. There is no actual effective date for the amendment in ASU 2013-12 but the amended definition of a public business entity is used in ASU 2014-01 and those that follow. The adoption of ASU 2013-12 did not have a material impact on the Company's results of operations, financial position or cash flows.

        Accounting Standards Updates—In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosures of Uncertainties about an Entity's Ability to Continue as a Going Concern ("ASU 2014-15"). ASU 2014-15 provides guidance in GAAP about management's responsibility to evaluate whether there is substantial doubt about an entity's ability to continue as a going concern and to provide related footnote disclosures. The amendments under ASU 2014-15 are effective for interim and annual fiscal periods beginning after December 15, 2016, with early adoption permitted. The Company plans to adopt ASU 2014-15 on January 1, 2015. The Company does not expect adoption of ASU 2014-15 will have a material impact on the Company's results of operations, financial position or cash flows.