Enanta Pharmaceuticals to Appeal Ruling Related to ‘953 Patent Infringement Lawsuit

Enanta Pharmaceuticals, Inc. (NASDAQ: ENTA), a clinical-stage biotechnology company dedicated to creating small molecule drugs for virology and immunology indications, today announced that the United States District Court of Massachusetts (“the Court”) has issued a ruling on a summary judgment motion filed by Pfizer, Inc. in connection with Enanta’s patent infringement lawsuit seeking damages for infringement of U.S. Patent No. 11,358,953 (“the ’953 Patent”) in the manufacture, use and sale of Pfizer’s COVID-19 antiviral, Paxlovid™ (nirmatrelvir tablets; ritonavir tablets).

The Court issued a summary judgment decision granting Pfizer’s motion that the ‘953 Patent is invalid. In its decision, the Court also denied Enanta’s partial motion for summary judgment of infringement as moot in light of its allowance of summary judgment on invalidity. Enanta plans to appeal the decision to the Court of Appeals for the Federal Circuit.

"The U.S. patent system and its protection of important innovations have enabled the robust development of new medicines and spurred growth in the biotechnology industry. We are proud of the impact our strong history of drug discovery work with protease inhibitors has had on antiviral treatments and the thousands of patients that have been treated with therapies using our patented inventions,” said Jay R. Luly, Ph.D., President and Chief Executive Officer of Enanta Pharmaceuticals, Inc. “We are disappointed with the Court’s ruling. We believe strongly in the merits of our case, and, through the appeal process, we will continue to defend our inventions from unlawful infringement.”

Enanta maintains its commitment to avoid attempting to impede the production, sale or distribution of Paxlovid.

About Enanta Pharmaceuticals, Inc.

Enanta is using its robust, chemistry-driven approach and drug discovery capabilities to become a leader in the discovery and development of small molecule drugs with an emphasis on indications in virology and immunology. Enanta’s clinical programs are currently focused on respiratory syncytial virus (RSV) and its earlier-stage immunology pipeline aims to develop treatments for inflammatory diseases by targeting key drivers of the type 2 immune response, including KIT and STAT6 inhibition.

Glecaprevir, a protease inhibitor discovered by Enanta, is part of one of the leading treatment regimens for curing chronic hepatitis c virus (HCV) infection and is sold by AbbVie in numerous countries under the tradenames MAVYRET® (U.S.) and MAVIRET® (ex-U.S.) (glecaprevir/pibrentasvir). A portion of Enanta’s royalties from HCV products developed under its collaboration with AbbVie contribute ongoing funding to Enanta’s operations. Please visit www.enanta.com for more information.

Forward-Looking Statements

This press release contains forward-looking statements, including statements with respect to Enanta’s suit against Pfizer, Inc. in the United States District Court for the District of Massachusetts seeking damages for patent infringement. Statements that are not historical facts are based on management’s current expectations, estimates, forecasts and projections about Enanta’s business and the industry in which it operates and management’s beliefs and assumptions. The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements. Important factors and risks that may affect actual results include: Enanta is competing to develop intellectual property in areas of small-molecule drug development that are highly competitive; issued patents, including the patent at issue in the Pfizer litigation, could be found invalid or unenforceable if challenged in court and could be costly to defend and be a distraction for Enanta’s senior management and scientific personnel; intellectual property litigation may lead to unfavorable publicity that harms Enanta’s reputation and causes the market price of its common stock to decline; and other risk factors described or referred to in “Risk Factors” in Enanta’s Form 10-K for the fiscal year ended September 30, 2024 and other periodic reports filed more recently with the Securities and Exchange Commission. Enanta cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Enanta undertakes no obligation to update or revise these statements, except as may be required by law.

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