The Company	6 Months Ended
Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	1. The Company Epizyme, Inc. (collectively referred to with its wholly owned, controlled subsidiary, Epizyme Securities Corporation, as “Epizyme” or the “Company”) is a commercial-stage biopharmaceutical company that is committed to rewriting treatment for people with cancer through the discovery, development, and commercialization of novel epigenetic medicines. The Company aspires to change the standard of care for patients and physicians by developing targeted medicines with fundamentally new mechanisms of action directed at specific causes of hematological malignancies and solid tumors. Through June 30, 2022, in addition to revenues from product sales, the Company has raised an aggregate of $1,650.2 million to fund its operations. This includes $268.8 million of non-equity funding through its collaboration agreements, $368.1 million of funding, consisting of $150.0 million in equity funding received through agreements with RPI Finance Trust ("RPI"), and $218.1 million in debt financing received through a loan agreement with BioPharma Credit Investments V (Master) LP and BPCR Limited Partnership (as transferee of BioPharma Credit Investments V (Master) LP’s interest as a lender) (the "Lenders"), $937.3 million from the sale of common stock and series A convertible preferred stock (the “Series A Preferred Stock”) in the Company’s public offerings and at-the-market offerings and $76.0 million from the sale of redeemable convertible preferred stock in private financings prior to the Company’s initial public offering in May 2013. As of June 30, 2022, the Company had $144.4 million in cash, cash equivalents and marketable securities. In 2020, the Company’s EZH2 inhibitor, tazemetostat, was approved in the United States as TAZVERIK for the treatment of epithelioid sarcoma ("ES"), and follicular lymphoma ("FL"). Commercial sales of TAZVERIK for the treatment of ES commenced in the first quarter of 2020 and commercial sales of TAZVERIK for the treatment of FL commenced in the end of the second quarter of 2020. The Company commenced active operations in early 2008. Since its inception, the Company has generated an accumulated deficit of $1,331.1 million through June 30, 2022 and will require substantial additional capital to fund its research, development, and commercialization efforts. The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, risks of failure of commercialization, clinical trials and preclinical studies, the need to obtain additional financing to fund the future development and commercialization of tazemetostat and the rest of its pipeline, the need to obtain marketing approval for its product candidates, the need to successfully commercialize and gain market acceptance of TAZVERIK and of any product candidates that may be approved in the future, the impact of the COVID-19 pandemic on the Company’s business, results of operations, and financial condition, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and ability to transition from clinical-stage manufacturing to commercial-stage production, marketing, and sale of products. Proposed Acquisition by Ipsen On June 27, 2022, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Ipsen Pharma SAS, a French société par actions simplifiée (the “Parent”), and Hibernia Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Ipsen Biopharmaceuticals, Inc., a Delaware corporation and wholly owned subsidiary of the Parent (“Purchaser”). Pursuant to the Merger Agreement, on July 12, 2022, the Purchaser commenced a tender offer (the “Offer”) to purchase all of the issued and outstanding shares of the Company’s common stock (the “Shares”) at a price of $1.45 per Share, payable to the holder of such common stock in cash, without interest, plus one non-transferable contractual contingent value right (“CVR”) per Share, which represents the right to receive one or more payments in cash, of up to $1.00 per CVR, contingent upon the achievement of certain specified milestones. As soon as practicable after the consummation of the Offer, and subject to the satisfaction or waiver of certain conditions as set forth in the Merger Agreement, and in accordance with Section 251(h) of the General Corporation Law of the State of Delaware, the Purchaser will be merged with and into the Company, without a meeting of the Company’s stockholders, and the Company will be continuing as the surviving corporation and a wholly owned subsidiary of the Parent (such merger, the “Merger”). As a result of the Merger, the Company will cease to be a publicly traded company. The Merger Agreement contains customary representations, warranties, and covenants. The Company currently expects the Offer and the Merger to be completed in the third quarter of 2022, subject to the satisfaction or waiver of customary closing conditions, including, among others, that the number of Shares tendered in the Offer represent at least one Share more than 50% of the total number of Shares outstanding immediately prior to the expiration of the Offer. The Merger Agreement provides the Parent and the Company with certain termination rights and, under certain circumstances, may require the Company to pay the Parent a termination fee of $9.9 million. For additional information related to the Merger Agreement, refer to the Company’s Solicitation/Recommendation Statement on Schedule 14D-9 filed with the U.S. Securities and Exchange Commission (“SEC”) on July 12, 2022, together with the exhibits and annexes thereto and as amended or supplemented from time to time. Please also see “Item 1A. Risk Factors—Risks Related to Our Pending Transaction with Ipsen Pharma SAS” of this Quarterly Report on Form 10-Q. Operating Cost Reduction In August 2021, the Company implemented a cross-functional reduction of approximately 11% of its then current workforce under a cost reduction plan. Affected employees were offered separation benefits, including severance payments along with temporary healthcare coverage assistance. The severance and termination-related costs totaled approximately $2.0 million, $1.6 million of which were recorded as selling general and administrative expenses and $0.4 million of which was recorded as research and development expenses in the third quarter of 2021. The Company expects that payments of these costs will be made through August 2022. In March 2022, the Company implemented further reductions of its expenses, including a pipeline reprioritization. Given the breadth of the Company’s then-current tazemetostat clinical development program, the Company decided to discontinue enrollment in its Phase 2 study of tazemetostat in combination with rituximab with FL in the third-line or later treatment settings (SYMPHONY-2, EZH-1401), as well as in its Phase 1/1b basket study evaluating tazemetostat combinations in patients with solid tumors (EZH-1301). The decision to discontinue these studies was based on evolving market dynamics and a continued focus on optimizing the Company’s investments and eliminating potentially overlapping studies. The Company continues to study tazemetostat in combination with other therapies for both hematologic and solid tumor malignancies, both in ongoing Company-sponsored studies as well as investigator-initiated studies. In addition, as part of the cost reduction plan, the Company implemented a cross-functional workforce reduction of approximately 12% of the Company’s then-current employees. The severance and termination related costs totaled approximately $2.5 million, $1.7 million of which were recorded as selling general and administrative expenses and $0.8 million of which were recorded as research and development expenses in the first quarter of 2022. The Company expects that payments of these costs will be made through December 2022.

The Company

6 Months Ended

Jun. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. The Company

Epizyme, Inc. (collectively referred to with its wholly owned, controlled subsidiary, Epizyme Securities Corporation, as “Epizyme” or the “Company”) is a commercial-stage biopharmaceutical company that is committed to rewriting treatment for people with cancer through the discovery, development, and commercialization of novel epigenetic medicines. The Company aspires to change the standard of care for patients and physicians by developing targeted medicines with fundamentally new mechanisms of action directed at specific causes of hematological malignancies and solid tumors.

Through June 30, 2022, in addition to revenues from product sales, the Company has raised an aggregate of $1,650.2 million to fund its operations. This includes $268.8 million of non-equity funding through its collaboration agreements, $368.1 million of funding, consisting of $150.0 million in equity funding received through agreements with RPI Finance Trust ("RPI"), and $218.1 million in debt financing received through a loan agreement with BioPharma Credit Investments V (Master) LP and BPCR Limited Partnership (as transferee of BioPharma Credit Investments V (Master) LP’s interest as a lender) (the "Lenders"), $937.3 million from the sale of common stock and series A convertible preferred stock (the “Series A Preferred Stock”) in the Company’s public offerings and at-the-market offerings and $76.0 million from the sale of redeemable convertible preferred stock in private financings prior to the Company’s initial public offering in May 2013. As of June 30, 2022, the Company had $144.4 million in cash, cash equivalents and marketable securities.

In 2020, the Company’s EZH2 inhibitor, tazemetostat, was approved in the United States as TAZVERIK for the treatment of epithelioid sarcoma ("ES"), and follicular lymphoma ("FL"). Commercial sales of TAZVERIK for the treatment of ES commenced in the first quarter of 2020 and commercial sales of TAZVERIK for the treatment of FL commenced in the end of the second quarter of 2020.

The Company commenced active operations in early 2008. Since its inception, the Company has generated an accumulated deficit of $1,331.1 million through June 30, 2022 and will require substantial additional capital to fund its research, development, and commercialization efforts. The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, risks of failure of commercialization, clinical trials and preclinical studies, the need to obtain additional financing to fund the future development and commercialization of tazemetostat and the rest of its pipeline, the need to obtain marketing approval for its product candidates, the need to successfully commercialize and gain market acceptance of TAZVERIK and of any product candidates that may be approved in the future, the impact of the COVID-19 pandemic on the Company’s business, results of operations, and financial condition, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and ability to transition from clinical-stage manufacturing to commercial-stage production, marketing, and sale of products.

Proposed Acquisition by Ipsen

On June 27, 2022, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Ipsen Pharma SAS, a French société par actions simplifiée (the “Parent”), and Hibernia Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Ipsen Biopharmaceuticals, Inc., a Delaware corporation and wholly owned subsidiary of the Parent (“Purchaser”). Pursuant to the Merger Agreement, on July 12, 2022, the Purchaser commenced a tender offer (the “Offer”) to purchase all of the issued and outstanding shares of the Company’s common stock (the “Shares”) at a price of $1.45 per Share, payable to the holder of such common stock in cash, without interest, plus one non-transferable contractual contingent value right (“CVR”) per Share, which represents the right to receive one or more payments in cash, of up to $1.00 per CVR, contingent upon the achievement of certain specified milestones.

As soon as practicable after the consummation of the Offer, and subject to the satisfaction or waiver of certain conditions as set forth in the Merger Agreement, and in accordance with Section 251(h) of the General Corporation Law of the State of Delaware, the Purchaser will be merged with and into the Company, without a meeting of the Company’s stockholders, and the Company will be continuing as the surviving corporation and a wholly owned subsidiary of the Parent (such merger, the “Merger”). As a result of the Merger, the Company will cease to be a publicly traded company.

The Merger Agreement contains customary representations, warranties, and covenants. The Company currently expects the Offer and the Merger to be completed in the third quarter of 2022, subject to the satisfaction or waiver of customary closing conditions, including, among others, that the number of Shares tendered in the Offer represent at least one Share more than 50% of the total number of Shares outstanding immediately prior to the expiration of the Offer. The Merger Agreement provides the Parent and the

Company with certain termination rights and, under certain circumstances, may require the Company to pay the Parent a termination fee of $9.9 million.

For additional information related to the Merger Agreement, refer to the Company’s Solicitation/Recommendation Statement on Schedule 14D-9 filed with the U.S. Securities and Exchange Commission (“SEC”) on July 12, 2022, together with the exhibits and annexes thereto and as amended or supplemented from time to time. Please also see “Item 1A. Risk Factors—Risks Related to Our Pending Transaction with Ipsen Pharma SAS” of this Quarterly Report on Form 10-Q.

Operating Cost Reduction

In August 2021, the Company implemented a cross-functional reduction of approximately 11% of its then current workforce under a cost reduction plan. Affected employees were offered separation benefits, including severance payments along with temporary healthcare coverage assistance. The severance and termination-related costs totaled approximately $2.0 million, $1.6 million of which were recorded as selling general and administrative expenses and $0.4 million of which was recorded as research and development expenses in the third quarter of 2021. The Company expects that payments of these costs will be made through August 2022.

In March 2022, the Company implemented further reductions of its expenses, including a pipeline reprioritization. Given the breadth of the Company’s then-current tazemetostat clinical development program, the Company decided to discontinue enrollment in its Phase 2 study of tazemetostat in combination with rituximab with FL in the third-line or later treatment settings (SYMPHONY-2, EZH-1401), as well as in its Phase 1/1b basket study evaluating tazemetostat combinations in patients with solid tumors (EZH-1301). The decision to discontinue these studies was based on evolving market dynamics and a continued focus on optimizing the Company’s investments and eliminating potentially overlapping studies. The Company continues to study tazemetostat in combination with other therapies for both hematologic and solid tumor malignancies, both in ongoing Company-sponsored studies as well as investigator-initiated studies. In addition, as part of the cost reduction plan, the Company implemented a cross-functional workforce reduction of approximately 12% of the Company’s then-current employees. The severance and termination related costs totaled approximately $2.5 million, $1.7 million of which were recorded as selling general and administrative expenses and $0.8 million of which were recorded as research and development expenses in the first quarter of 2022. The Company expects that payments of these costs will be made through December 2022.