(1) The Company and Summary of Significant Accounting Policies

Description of Business

ARCA biopharma, Inc., or the Company or ARCA, a Delaware corporation, is headquartered in Westminster, Colorado. The Company is a biopharmaceutical company principally focused on developing genetically-targeted therapies for cardiovascular diseases. The Company’s lead product candidate, Gencaro™ (bucindolol hydrochloride), is a pharmacologically unique beta-blocker and mild vasodilator that ARCA is evaluating in a clinical trial for the treatment of atrial fibrillation, or AF, in patients with heart failure with reduced left ventricular ejection fraction (HFREF). The Company has identified common genetic variations in receptors in the cardiovascular system that it believes interact with Gencaro’s pharmacology and may predict patient response to the drug.

The Company is testing this hypothesis in a Phase 2B/Phase 3 clinical trial of Gencaro, known as GENETIC-AF. The AF indication for Gencaro was chosen based on clinical data from a prior Phase 3 heart failure (HF) trial of Gencaro in 2,708 HF patients, or the BEST trial, which suggested that Gencaro may be successful in reducing or preventing AF.

GENETIC-AF is a Phase 2B/Phase 3 multi-center, randomized, double-blind, adaptive design clinical trial comparing the safety and efficacy of Gencaro against an active comparator, the beta-blocker Toprol XL (metoprolol succinate), that seeks to enroll a combined total of approximately 620 patients. Eligible patients will have HFREF, have a history of paroxysmal AF (episodes lasting 7 days or less) or persistent AF (episodes lasting more than 7 days and less than 1 year) in the past 6 months, and have the beta-1 389 arginine homozygous genotype that the Company believes responds most favorably to Gencaro. The primary endpoint of the study is time to first event of symptomatic AF/atrial flutter (AFL), or all-cause mortality. The GENETIC-AF Data Safety Monitoring Board (DSMB) will conduct a pre-specified interim analysis of study endpoints for efficacy, safety and futility to recommend whether the trial should proceed to Phase 3. The DSMB will make its recommendation based on a predictive probability analysis of certain trial data after a sufficient number of patients have evaluable endpoint data. An enrolled patient has evaluable endpoint data either when they experience their first endpoint event, or after they complete the 24 week follow up period. The DSMB interim analysis will focus on analyses of the AF/AFL endpoints in the trial using both clinical-based intermittent monitoring and device-based continuous monitoring techniques. Should the DSMB interim analysis indicate that the data are consistent with pre-trial statistical assumptions and the potential for achieving statistical significance for the Phase 3 endpoint, the DSMB may recommend that the study proceed to Phase 3. The DSMB may also halt the study for futility. Based on the current enrollment rate, the Company expects to enroll at least 150 patients by the end of 2016. The Company expects the outcome of the DSMB interim analysis and recommendation regarding the potential transition to Phase 3 in the first half of 2017. Should the DSMB recommend that the study proceed to Phase 3, the trial would continue enrolling to a total of approximately 620 patients, subject to the Company obtaining sufficient financing to fund the Phase 3 portion of the trial.

If the Company proceeds with the Phase 3 portion of the GENETIC-AF, it will need to raise additional capital to complete the Phase 3 portion of the GENETIC-AF clinical trial and submit for FDA approval. If the Company is unable to obtain additional funding or is unable to complete a strategic transaction, it may have to discontinue development activities on Gencaro or discontinue its operations.

On January 27, 2009, the Company completed a business combination, or the Merger, with Nuvelo, Inc. (Nuvelo). Immediately following the Merger, the Company changed its name from Nuvelo, Inc. to ARCA biopharma, Inc.

Liquidity and Going Concern

The Company devotes substantially all of its efforts towards obtaining regulatory approval and raising capital necessary to fund its operations and it is subject to a number of risks associated with clinical research and development, including dependence on key individuals, the development of and regulatory approval of commercially viable products, the need to raise adequate additional financing necessary to fund the development and commercialization of its products, and competition from larger companies. The Company has not generated revenue to date and has incurred substantial losses and negative cash flows from operations since its inception. The Company has historically funded its operations through issuances of common and preferred stock.

In June 2015 and February 2014, the Company raised approximately $34.2 million and $7.9 million in net proceeds, respectively, to provide additional funds for the Phase 2B/Phase 3 GENETIC-AF trial and the Company’s ongoing operations. The Company is enrolling patients in the Phase 2B portion of the GENETIC-AF trial, and the Company believes that its current cash and cash equivalents will be sufficient to fund its operations, at its projected cost structure, through at least the end of 2017. However, in light of the significant uncertainties regarding clinical development timelines and costs for developing drugs such as Gencaro, the Company expects to raise additional capital to finance the completion of GENETIC-AF and the Company’s future operations. If the Company is delayed in completing or is unable to complete additional funding and/or a strategic transaction, the Company may discontinue its development activities or operations.

The Company’s liquidity, and its ability to raise additional capital or complete any strategic transaction, depends on a number of factors, including, but not limited to, the following:

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progress of GENETIC-AF, including enrollment and any data that may become available;

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the costs and timing for the planned GENETIC-AF clinical trial in order to gain possible FDA approval for Gencaro;

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the market price of the Company’s stock and the availability and cost of additional equity capital;

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the Company’s ability to retain the listing of its common stock on the Nasdaq Capital Market;

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general economic and industry conditions affecting the availability and cost of capital;

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the Company’s ability to control costs associated with its operations;

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the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights; and

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the terms and conditions of the Company’s existing collaborative and licensing agreements.

The sale of additional equity or convertible debt securities would likely result in substantial additional dilution to the Company’s stockholders. If the Company raises additional funds through the incurrence of indebtedness, the obligations related to such indebtedness would be senior to rights of holders of the Company’s capital stock and could contain covenants that would restrict the Company’s operations. The Company also cannot predict what consideration might be available, if any, to the Company or its stockholders, in connection with any strategic transaction. Should strategic alternatives or additional capital not be available to the Company, or not be available on acceptable terms, the Company may be unable to realize value from its assets and discharge its liabilities in the normal course of business which may, among other alternatives, cause the Company to further delay, substantially reduce or discontinue operational activities to conserve its cash resources.

There are significant uncertainties surrounding the clinical development timelines and costs and the need to raise a significant amount of capital in the future. These financial statements have been prepared with the assumption that the Company will continue as a going concern and will be able to realize its assets and discharge its liabilities in the normal course of business and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the inability of the Company to continue as a going concern. The Company may not be able to raise sufficient capital on acceptable terms, or at all, to continue development of Gencaro or to otherwise continue operations and may not be able to execute any strategic transaction.

Reverse Stock Split

On September 3, 2015, the Company completed a 1-for-7 reverse split of its common stock. All common shares and per common share amounts in the financial statements and footnotes have been adjusted retroactively to reflect the effects of this action.

Basis of Presentation

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include all adjustments necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented. Our management performed an evaluation of our activities through the date of filing of this Annual Report on Form 10-K, and concluded that there are no subsequent events to disclose.

Recent Accounting Pronouncements

In June 2014, the Financial Accounting Standards Board (FASB) issued FASB Accounting Standards Update (“ASU”) No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation which removes Topic 915 from the FASB Accounting Standards Codification and removes from GAAP the concept of a development stage entity along with the associated incremental financial reporting requirements for development stage entities. The ASU is effective for fiscal years beginning after December 15, 2014, with early adoption being permitted for annual or interim periods for which financial statements have not been issued. The Company early-adopted this guidance as of June 30, 2014 and as a result, removed references to being a development stage entity and inception-to-date results from these financial statements.

In August 2014, the FASB issued FASB Accounting Standards Update (“ASU No. 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 No. 2014-15 will be effective for fiscal years and interim periods ending after December 15, 2016, with early adoption being permitted for annual and interim periods for which financial statements have not been issued. ASU 2014-15 requires that management evaluate at each annual and interim reporting period whether there is a substantial doubt about an entity’s ability to continue as a going concern within one year of the date that the financial statements are issued. The significant uncertainties surrounding the clinical development timelines and costs and the need to raise a significant amount of capital raises substantial doubt about the Company’s ability to continue as a going concern for a reasonable period of time. The Company does not expect a significant impact on the financial position, results of operations or disclosures upon adoption of this guidance.

In April 2015, the FASB issued Accounting Standards Update No. 2015-05: Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement ("ASU 2015-05"). The amendments in this update provide guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the update specifies that the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. The update further specifies that the customer should account for a cloud computing arrangement as a service contract if the arrangement does not include a software license. ASU 2015-05 will be effective for fiscal years beginning after December 31, 2015. The Company is currently assessing the future impact of this update to the financial statements.

In November 2015, the FASB issued Accounting Standards Update No. 2015-17: Balance Sheet Classification of Deferred Taxes ("ASU 2015-17") that requires deferred income tax liabilities and assets to be classified as noncurrent. The standard is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted. The Company early-adopted this guidance as of December 31, 2015 retrospectively and as a result, reclassified our December 31, 2014 current deferred tax asset, and related valuation allowance, to noncurrent in the summary table in Note 10, Income Taxes. Since there is a full valuation allowance on all deferred taxes, there was no impact on our Balance Sheets, Statements of Operations and Comprehensive Loss or Statements of Cash Flows as a result of adoption of this guidance.

Accounting Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America 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 expenses during the reporting period. The Company bases estimates on various assumptions that are believed to be reasonable under the circumstances. The Company believes significant judgment was involved in estimating the clinical trial accruals, and in estimating other accrued liabilities, stock-based compensation, and income taxes. Management is continually evaluating and updating these estimates, and it is possible that these estimates will change in the future or that actual results may differ from these estimates.

Cash Equivalents

Cash equivalents generally consist of money market funds and debt securities with maturities of 90 days or less at the time of purchase. The Company invests its excess cash in securities with strong ratings and has established guidelines relative to diversification and maturity with the objective of maintaining safety of principal and liquidity.

The Company classifies all cash equivalents as available-for-sale securities, and records investments at fair value.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company has no off-balance-sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements. The Company maintains cash and cash equivalent balances in the form of bank demand deposits and money market fund accounts with financial institutions that management believes are creditworthy. Such balances may at times exceed the insured amount.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Cost includes expenditures for equipment, leasehold improvements, replacements, and renewals. Maintenance and repairs are charged to expense as incurred. When assets are sold, retired, or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in operations. The cost of property and equipment is depreciated using the straight-line method over the estimated useful lives of the related assets. Leasehold improvements are amortized over the shorter of the life of the lease or the estimated useful life of the assets. Property and equipment acquired in the Merger were recorded at the estimated fair value as of the date of the Merger, and are subsequently depreciated using the straight-line method over the estimated remaining useful lives of the related assets.

Accrued Expenses

As part of the process of preparing its financial statements, the Company is required to estimate accrued expenses. This process involves identifying services that third parties have performed on the Company’s behalf and estimating the level of service performed and the associated cost incurred for these services as of the balance sheet date. Examples of estimated accrued expenses include contract service fees, such as fees payable to contract manufacturers in connection with the production of materials related to the Company’s drug product, and professional service fees, such as attorneys, consultants, and clinical research organizations. The Company develops estimates of liabilities using its judgment based upon the facts and circumstances known at the time.

Segments

The Company operates in one segment. Management uses one measure of profitability and does not segment its business for internal reporting.

Research and Development

Research and development costs are expensed as incurred. These consist primarily of salaries, contract services, and supplies.

Costs related to clinical trial and drug manufacturing activities are based upon estimates of the services received and related expenses incurred by contract research organizations, or CROs, clinical study sites, drug manufacturers, collaboration partners, laboratories, consultants, or otherwise. Related contracts vary significantly in length, and could be for a fixed amount, a variable amount based on actual costs incurred, capped at a certain limit, or for a combination of these elements. Activity levels are monitored through communications with the vendors, including detailed invoices and task completion review, analysis of expenses against budgeted amounts, and pre-approval of any changes in scope of the services to be performed. Certain significant vendors may also provide an estimate of costs incurred but not invoiced on a periodic basis. Expenses related to the CROs and clinical studies, as well as contract drug manufacturers, are primarily based on progress made against specified milestones or targets in each period.

In accordance with certain research and development agreements, we are obligated to make certain upfront payments upon execution of the agreement. We record these upfront payments as prepaid research and development expenses, which are included in Other current assets or Other assets in the accompanying Balance Sheets. Such payments are recorded to research and development expense as services are performed. We evaluate on a quarterly basis whether events and circumstances have occurred that may indicate impairment of remaining prepaid research and development expenses.

Stock-Based Compensation

The Company’s stock-based compensation cost recognized is based on the estimated grant date fair value. The Company recognizes compensation costs for its share-based awards on a straight-line basis over the requisite service period for the entire award, as adjusted for expected forfeitures.

Income Taxes

The current benefit for income taxes represents actual or estimated amounts payable or refundable on tax returns filed or to be filed each year. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The overall change in deferred tax assets and liabilities for the period measures the deferred tax expense or benefit for the period. The measurement of deferred tax assets may be reduced by a valuation allowance based on judgmental assessment of available evidence if deemed more likely than not that some or all of the deferred tax assets will not be realized. The Company has recorded a valuation allowance against all of its deferred tax assets, as management has concluded that it is more likely than not that the net deferred tax asset will not be realized through future taxable income, based primarily on the Company’s history of operating losses. The Company has not performed an Internal Revenue Code Section 382 limitation study. Depending on the outcome of such a study, the gross amount of net operating losses recognizable in future tax periods could be limited.