Nature of the Business and Summary of Significant Accounting Policies | 1. Nature of the Business and Summary of Significant Accounting Policies Nature of the Business Merrimack Pharmaceuticals, Inc. (the “Company”) is a clinical stage biopharmaceutical company based in Cambridge, Massachusetts that is outthinking cancer by targeting biomarker-defined cancers. The Company’s vision is to ensure that cancer patients and their families live fulfilling lives. The Company’s mission is to transform cancer care through the smart design and development of targeted solutions based on a deep understanding of cancer pathways and biological markers. All of the Company’s development programs, including four clinical trials and six candidates in preclinical development, fit into the Company’s strategy of (1) understanding the biological problems it is trying to solve, (2) designing specific solutions against the problems it is trying to solve and (3) developing those solutions for biomarker-selected patients. This three-pronged strategy seeks to ensure optimal patient outcomes. On April 3, 2017, The Company’s non-commercial assets, including its clinical and preclinical development programs, were not included in the Asset Sale and remain assets of the Company. The Company’s most advanced assets and a description of the status of each asset is as follows: • MM-121 (seribantumab) : MM-121 is a fully human monoclonal antibody that binds to the ErbB3 (HER3) receptor and targets heregulin positive cancers. There are two active development programs for MM-121, each in a Phase 2 clinical trial. The Company is currently conducting the global, open-label, biomarker-selected, Phase 2 randomized SHERLOC clinical trial, evaluating MM-121 in combination with docetaxel in patients with heregulin positive non-small cell lung cancer. The Company is also conducting the global, double-blinded, placebo-controlled, biomarker-selected, Phase 2 randomized SHERBOC clinical trial evaluating MM-121 in combination with fulvestrant in patients with heregulin positive, hormone receptor positive, ErbB2 (HER2) negative, metastatic breast cancer; • MM-141 (istiratumab) : MM-141 is a fully human tetravalent bispecific antibody designed to block tumor survival signals by targeting receptor complexes containing the insulin-like growth factor 1 (“IGF-1”), receptor and ErbB3 (HER3) cell surface receptor. The Company is currently conducting and has completed enrollment of the global, double-blinded, placebo-controlled, Phase 2 randomized CARRIE clinical trial evaluating MM-141 in combination with nab-paclitaxel and gemcitabine in patients with previously untreated metastatic pancreatic cancer with high serum levels of free IGF-1; and • MM-310 : MM-310 is an antibody-directed nanotherapeutic that contains a novel prodrug of the highly potent chemotherapy docetaxel and targets the ephrin receptor A2 receptor, which is highly expressed in most solid tumor types, such as prostate, ovarian, bladder, gastric, pancreatic and lung cancers. The Company initiated a Phase 1 clinical trial to evaluate safety and preliminary activity of MM-310 and to identify the maximum tolerated dose in the first quarter of 2017. The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, among other things, its ability to secure additional capital to fund operations, success of clinical trials, development by competitors of new technological innovations, dependence on collaborative arrangements, protection of proprietary technology, compliance with government regulations and dependence on key personnel. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of capital, adequate personnel, infrastructure and extensive compliance reporting capabilities. The Company’s product candidates are in development. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies, among others. In addition, the Company is dependent upon the services of its employees and consultants. In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern The Company will ultimately need to seek additional funding through public or private equity or debt financings, through existing or new collaboration arrangements, or through divestitures of its assets. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into additional collaborative arrangements or divest its assets. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. Arrangements with collaborators or others may require the Company to relinquish rights to certain of its technologies or product candidates. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate its research and development programs or commercialization efforts, which could adversely affect its business prospects. Summary of Significant Accounting Policies The Company’s significant accounting policies include policies related to both continuing and discontinuing operations. Segment Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business as one operating segment and the Company operates in only one geographic region (the United States). Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared under U.S. generally accepted accounting principles (“GAAP”) and include the accounts of the Company and its wholly owned subsidiary. As of March 31, 2017, the Commercial Business met all the conditions to be classified as held-for-sale and represents a discontinued operation since the disposal of the Commercial Business is a strategic shift that will have a major effect on the Company’s operations and financial results. The Company will not have further significant involvement in the operations of the discontinued Commercial Business. The operating results of the Commercial Business are reported as discontinued operations, net of tax in the consolidated statements of operations and comprehensive income (loss) for all periods presented. In addition, in the consolidated balance sheet as of December 31, 2016, the assets and liabilities held for sale have been presented separately. For additional information, see Note 2, “Discontinued Operations – Sale of Commercial Business.” The consolidated financial statements have historically included the accounts of the Company and Silver Creek Pharmaceuticals, Inc. (“Silver Creek”) with all intercompany transactions and balances eliminated in consolidation. Silver Creek represented a variable interest entity that the Company consolidated as the primary beneficiary. As discussed in Note 3, “Investment in Silver Creek,” Silver Creek completed a preferred stock financing in the third quarter of 2017, which reduced the Company’s ownership percentage in Silver Creek below 50% and resulted in the Company no longer controlling the Silver Creek board of directors. The Company determined that it is no longer the primary beneficiary of Silver Creek since the Company does not control the board of directors and does not direct the activities that have the most significant impact on Silver Creek’s economic performance. Therefore, the Company deconsolidated Silver Creek from its financial statements in the third quarter of 2017 in accordance with ASC 810-10-40-4(c), Consolidation The Company’s consolidated balance sheet as of December 31, 2016 included Silver Creek’s assets and liabilities, after intercompany eliminations. The Company’s consolidated balance sheet as of December 31, 2017 does not include the assets and liabilities of Silver Creek since the Company deconsolidated Silver Creek in the third quarter of 2017. The Company’s consolidated statements of operations and comprehensive income (loss) for the year ended December 31, 2017 include Silver Creek’s results for the period through July 13, 2017, the day immediately preceding the deconsolidation of Silver Creek. On August 11, 2017, the Company’s stockholders approved an amendment to the Company's certificate of incorporation to effect a one-for-ten reverse stock split of its issued and outstanding common stock (the “Reverse Split”). On September 5, 2017, the Company filed an amendment to its certificate of incorporation to effect the Reverse Split, and on September 6, 2017, the Reverse Split was effective for trading purposes. As a result of the Reverse Split, every ten shares of common stock issued and outstanding was converted into one share of common stock, reducing the number of issued and outstanding shares of common stock from approximately 132.8 million shares to approximately 13.28 million shares. No fractional shares were issued in connection with the Reverse Split. The amendment to the certificate of incorporation also proportionately reduced the number of authorized shares of common stock from 200 million to 20 million. The Reverse Split did not change the par value of the common stock. The Reverse Split did not change the number of authorized shares or par value of the Company’s preferred stock, of which there are no shares issued or outstanding. All outstanding stock options and convertible notes entitling their holders to purchase shares of common stock or acquire shares of common stock upon conversion, as the case may be, were adjusted as a result of the Reverse Split, as required by the terms of these securities. This change is reflected throughout the financial statements as appropriate. As a result, all share and per share amounts have been adjusted retroactively to reflect the Reverse Split for all periods. For additional information, see Note 14, “Stock-Based Compensation.” Use of Estimates GAAP requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures. The Company bases estimates and judgments on historical experience and on various other factors that it believes to be reasonable under the circumstances. The most significant estimates in these consolidated financial statements include, but may not be limited to, revenue recognition, estimates utilized in the valuation of inventory, accounting for stock-based compensation and accrued expenses. The Company’s actual results may differ from these estimates under different assumptions or conditions. The Company evaluates its estimates on an ongoing basis. Changes in estimates are reflected in reported results in the period in which they become known by the Company’s management. Certain estimates, such as revenue recognition, estimates of discounts and allowances related to commercial sales of ONIVYDE, estimates utilized in the valuation of inventory, useful lives with respect to long-lived assets and intangible assets, contingencies, intangible assets, goodwill and in-process research and development (“IPR&D”) related specifically to the Commercial Business, which has been reclassified under discontinued operations and included in assets and liabilities held for sale. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents are short-term, highly liquid investments with original maturities of three months or less at the date of purchase. Investments qualifying as cash equivalents primarily consist of money market funds, commercial paper, corporate notes and bonds and certificates of deposit. Cash accounts with any type of restriction are classified as restricted cash. If restrictions are expected to be lifted in the next twelve months, the restricted cash account is classified as current. As of December 31, 2017 and 2016, the Company recorded restricted cash of $0.8 million and $0.8 million, respectively, which was primarily related to the Company’s facility lease. Marketable Securities The Company classifies marketable securities with a remaining maturity when purchased of greater than three months as available-for-sale. Available-for-sale securities are carried at fair value, with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity (deficit) until realized. To determine whether an other-than-temporary impairment exists, the Company performs an analysis to assess whether it intends to sell, or whether it would more likely than not be required to sell, the security before the expected recovery of the amortized cost basis. Where the Company intends to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is recognized on the statement of operations and comprehensive income (loss) as an other-than-temporary impairment charge. When this is not the case, the Company performs additional analysis on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where the Company does not expect to receive cash flows, based on using a single best estimate, sufficient to recover the amortized cost basis of a security and amount of the loss recognized in other income (expense). Realized gains and losses are recognized in interest income. Any premium or discount arising at purchase is amortized and/or accreted to interest income. The Company did not have any marketable securities as of December 31, 2017 or 2016. Inventory The Company values its inventories at the lower of cost or net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and manufacturing overhead, on a first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded as a component of “Cost of revenues.” The Company capitalizes inventory costs associated with the Company’s products after regulatory approval when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Inventory acquired prior to receipt of marketing approval of a product candidate is expensed as research and development expense as incurred. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign. Shipping and handling costs for product shipments are recorded as incurred as a component of “Cost of revenues” along with amortization expense related to definite-lived intangible assets, costs associated with manufacturing the product and any inventory reserves or write-downs. As a result of the Asset Sale, all inventory relates to the Commercial Business and has been reclassified under discontinued operations. Property and Equipment Property and equipment, including leasehold improvements, are recorded at cost and depreciated when placed into service using the straight-line method, based on their estimated useful lives as follows: Asset Classification Estimated Useful Life (in years) Lab equipment 3 - 7 IT equipment 3 - 7 Leaseholds improvements Lesser of useful life or lease term Furniture and fixtures 3 - 7 Costs for capital assets not yet placed into service have been capitalized as construction-in-progress and will be depreciated in accordance with the above guidelines once placed into service. Costs for repairs and maintenance are expensed as incurred, while major betterments are capitalized. The Company capitalizes interest cost incurred on funds used to construct property and equipment. The capitalized interest is recorded as part of the asset to which it relates and is depreciated over the asset’s estimated useful life. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in earnings. The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of assets may not be fully recoverable or that the useful lives of these assets are no longer appropriate. Each impairment test is based on a comparison of the undiscounted cash flow to the recorded value of the asset. If impairment is indicated, the asset will be written down to its estimated fair value on a discounted cash flow basis. Goodwill and Intangible Assets Goodwill and indefinite-lived intangible assets, including IPR&D assets, are evaluated for impairment on an annual basis or more frequently if an indicator of impairment is present. The Company performs its annual goodwill and IPR&D impairment evaluations on August 31 st When performing an evaluation of goodwill impairment, the Company has the option to first assess qualitative factors to determine whether it is necessary to perform the quantitative two-step impairment test. If the Company elects this option and finds, as a result of the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the quantitative two-step impairment test is required; otherwise, further testing is not required. This requires the Company to assess the impact of significant events, milestones and changes to expectations and activities that may have occurred since the last impairment evaluation. Significant changes to these estimates, judgments and assumptions could materially change the outcome of the impairment assessment. Alternatively, the Company may elect to not first assess qualitative factors and immediately perform the quantitative two-step impairment test. If such an election occurs, in the first step, the fair value of the Company’s reporting unit is compared to the carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the second step of the impairment test is performed in order to determine the implied fair value of the reporting unit’s goodwill. If the carrying value of the reporting unit’s goodwill exceeds the implied fair value, then the Company would record an impairment loss equal to the difference. As described above, the Company operates in one operating segment, which is considered the only reporting unit. As a result of the Asset Sale, all goodwill and intangible assets relate to the Commercial Business and have been reclassified under discontinued operations. Accrued Expenses As part of the process of preparing financial statements, the Company is required to estimate accrued expenses. This process involves identifying services that have been performed on the Company’s behalf and estimating the level of services performed and the associated costs incurred for such services where the Company has not yet been invoiced or otherwise notified of actual cost. The Company records these estimates in its consolidated financial statements as of each balance sheet date. Examples of estimated accrued expenses include: • fees due to contract research organizations in connection with preclinical and toxicology studies and clinical trials; • fees paid to investigative sites in connection with clinical trials; and • professional service fees. In accruing service fees, the Company estimates the time period over which services will be provided and the level of effort in each period. If the actual timing of the provision of services or the level of effort varies from the estimate, the Company adjusts the accrual accordingly. In the event that the Company does not identify costs that have been incurred or it under or overestimates the level of services performed or the costs of such services, its actual expenses could differ from such estimates. The date on which some services commence, the level of services performed on or before a given date and the cost of such services are often subjective determinations. The Company prepares its estimates based on the facts and circumstances known to it at the time and in accordance with GAAP. There have been no material changes in estimates for the periods presented. Non-Controlling Interest Non-controlling interest represents the non-controlling stockholders’ proportionate share of preferred stock and net loss of the Company’s majority owned consolidated subsidiary, Silver Creek. The non-controlling stockholders’ proportionate share of the preferred stock in Silver Creek is reflected as non-controlling interest in the Company’s consolidated balance sheets as a component of mezzanine equity. As discussed in Note 3, “Investment in Silver Creek,” Silver Creek completed a preferred stock financing in the third quarter of 2017, which reduced the Company’s ownership percentage in Silver Creek below 50% and resulted in the Company no longer controlling the Silver Creek board of directors. The Company determined that it is no longer the primary beneficiary of Silver Creek since the Company does not control the board of directors and does not direct the activities that have the most significant impact on Silver Creek’s economic performance. Therefore, the Company deconsolidated Silver Creek from its financial statements in the third quarter of 2017 in accordance with ASC 810-10-40-4(c), Consolidation Revenue Recognition The Company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the price to the customer is fixed or determinable; and collectability is reasonably assured. Product Revenues, Net Prior to the Asset Sale, the Company sold ONIVYDE to a limited number of specialty pharmaceutical distributors in the United States (collectively, its “Distributors”). The Company’s Distributors subsequently resold the products to healthcare providers. The Company recognized revenue on product sales when title and risk of loss had passed to the Distributor, which was typically upon delivery. Product revenues were recorded net of applicable reserves for discounts and allowances. As a result of the Asset Sale, all product revenues relate to the Commercial Business and have been reclassified under discontinued operations. In order to conclude that the price is fixed or determinable, the Company must be able to reasonably estimate its net product revenues upon delivery to its Distributors. As such, the Company estimated its net product revenues by deducting from its gross product revenues trade allowances, estimated contractual discounts, estimated Medicaid rebates, estimated reserves for product returns and estimated costs of other incentives offered to patients. These discounts and allowances were based on estimates of the amounts earned or to be claimed on the related sales. The Company’s estimates took into consideration its historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted Distributor buying and payment patterns. Actual amounts may ultimately differ from the Company’s estimates. If actual results varied, the Company would adjust these estimates, which could have an effect on earnings in the period of adjustment. Product revenue reserves and allowances that reduce gross revenue are categorized as follows: Trade Allowances: The Company paid fees to its Distributors for providing certain data to the Company as well as for maintaining contractual inventory and service levels. These trade allowances were recorded as a reduction to accounts receivable on the consolidated balance sheet at the time revenue is recognized. Rebates and Chargeback Discounts: The Company was subject to discount obligations under state Medicaid programs and the Public Health Service 340B Drug Pricing Program, contracts with Federal government entities purchasing via the Federal Supply Schedule and various private organizations, such as group purchasing organizations (collectively, its “Third-party Payors”). The Company estimated the rebates and chargeback discounts it provided to Third-party Payors, based upon its estimated payor mix, and deducted these estimated amounts from its gross product revenues at the time revenue was recognized. Chargeback discounts were processed when the Third-party Payor purchased the product at a discount from the Distributor, who then in turn charged back to the Company the difference between the price initially paid by the Distributor and the discounted price paid by the Third-party Payor. These chargeback discounts were recorded as a reduction to accounts receivable on the consolidated balance sheet at the time revenue was recognized. Rebates that were invoiced directly to the Company were recorded as accrued liabilities on the consolidated balance sheet at the time revenue was recognized. Product Returns: An allowance for product returns was established for returns expected to be made by Distributors and was recorded at the time revenue was recognized, resulting in a reduction to product sales. In accordance with contractual terms, Distributors had the right to return unopened and undamaged product that was within a permissible number of months before and after the product’s expiration date, subject to contractual limitations. The Company had the ability to monitor inventory levels and the shelf life of product at Distributors and could contractually control the amount of inventory that was sold to Distributors. Based on inventory levels held by Distributors and the structure of the Company’s distribution model, the Company concluded that it had the ability to reasonably estimate product returns at the time revenue was recognized. The Company’s estimated rate of return was based on historical rates of return for comparable oncology products. Other Incentives: The Company offered co-pay mitigation support to commercially insured patients. The Company’s co-pay mitigation program was intended to reduce each participating patient’s portion of the financial responsibility for a product’s purchase price to a specified dollar amount. Based upon the terms of the Company’s co-pay mitigation program, the Company estimated average co-pay mitigation amounts in order to establish a reserve for co-pay mitigation claims and deducted these estimated amounts from its gross product revenues at the later of the date that (i) the revenues were recognized or (ii) the incentive was offered. Claims under the Company’s co-pay mitigation program were subject to expiration. All product revenue recognized relates to the Commercial Business and is presented as income from discontinued operations, net of tax in the consolidated statements of operations and comprehensive income (loss) for all periods presented. In addition, in the consolidated balance sheet as of December 31, 2016, the balance sheet accounts described above are included in assets and liabilities held for sale. License and Collaboration Revenues The Company enters into biopharmaceutical product development agreements with collaborative partners for the research and development of therapeutic and diagnostic products. The terms of the agreements may include nonrefundable signing and licensing fees, funding for research, development and manufacturing, milestone payments and royalties or profit-sharing on any product sales derived from collaborations. These multiple-element arrangements are analyzed to determine whether the deliverables can be separated or whether they must be accounted for as a single unit of accounting. The revenue recognition guidance related to multiple-element arrangements requires entities to separate and allocate consideration in a multiple-element arrangement according to the relative selling price of each deliverable. The fair value of deliverables under the arrangement may be derived using a best estimate of selling price if vendor specific objective evidence and third-party evidence are not available. Deliverables under the arrangement will be separate units of accounting provided that a delivered item has value to the customer on a stand-alone basis and if the arrangement does not include a general right of return relative to the delivered item and delivery or performance of the undelivered item is considered probable and substantially in the control of the vendor. In September 2014, the Company entered into the Baxalta Agreement with Baxter International Inc., Baxter Healthcare Corporation and Baxter Healthcare SA (collectively, “Baxter”) for the development and commercialization of ONIVYDE outside of the United States and Taiwan (the “Licensed Territory”). In connection with Baxter International Inc.’s separation of the Baxalta business, the Baxalta Agreement was assigned to Baxalta during the second quarter of 2015. The Baxalta Agreement was evaluated under the accounting guidance on revenue recognition for multiple-element arrangements. The Company determined that the obligations under this agreement represent a single unit of accounting and that the agreement represents a services agreement. As a result, the Company has estimated the level of effort expected to be completed as a result of providing the identified deliverables and will recognize revenue related to the agreement based on proportional performance as effort is completed over the expected services period. The Company also entered into a development, license and supply agreement (the “Actavis Agreement”) with Watson Laboratories, Inc. (“Actavis”) in November 2013, which was evaluated under the accounting guidance on revenue recognition for multiple-element arrangements. All operating results recognized related to the Baxalta Agreement and Actavis Agreement are presented as income from discontinued operations, net of tax in the consolidated statements of operations and comprehensive income (loss) for all periods presented. In addition, in the consolidated balance sheet as of December 31, 2016, the assets and liabilities related to the Baxalta Agreement and Actavis Agreement have been presented separately as assets and liabilities held for sale. Both the Baxalta Agreement and Actavis Agreement were assigned to Ipsen in connection with the completion of the Asset Sale. Whenever the Company determines that an arrangement should be accounted for as a single unit of accounting, it determines the period over which the performance obligations would be performed and revenue would be recognized. If the Company cannot reasonably estimate the timing and the level of effort to complete its performance obligations under the arrangement, then revenue under the arrangement is recognized on a straight-line basis over the period the Company expects to complete its performance obligations. The Company’s collaboration agreements may include additional payments upon the achievement of performance-based milestones. As milestones are achieved, a portion of the milestone payment, equal to the percentage of the total time that the Company has performed the performance obligations to date divided by the total estimated time to complete the performance obligations, multiplied by the amount of the milestone payment, will be recognized as revenue upon achievement of such milestone. The remaining portion of the milestone will be recognized over the remaining performance period. Milestones that are tied to regulatory approvals are not considered probable of being achieved until such approval is received. Milestones |