Enanta Pharmaceuticals to Challenge Ruling on ‘953 Patent Infringement Lawsuit

Watertown, Mass. – December 24, 2024 — Enanta Pharmaceuticals, Inc. (NASDAQ: ENTA), a clinical-stage biotechnology company specializing in innovative small molecule therapies for virology and immunology, announced that the United States District Court of Massachusetts has issued a ruling in favor of Pfizer, Inc. regarding Enanta’s patent infringement lawsuit. The case centers on U.S. Patent No. 11,358,953 (the ‘’953 Patent), which Enanta Pharmaceuticals alleges Pfizer infringed upon through the development, manufacture, and sale of its COVID-19 antiviral, Paxlovid™ (nirmatrelvir and ritonavir tablets).

The Court’s summary judgment declared the ‘953 Patent invalid, effectively dismissing Enanta’s motion for partial summary judgment on infringement as moot. In response, Enanta Pharmaceuticals has announced its intention to appeal the ruling to the United States Court of Appeals for the Federal Circuit.

Enanta’s Commitment to Innovation and Advocacy

“The U.S. patent system is critical for protecting groundbreaking innovations, driving progress in biotechnology, and enabling the creation of life-saving medicines. Our work in protease inhibitors has made a significant impact on antiviral treatments, benefiting countless patients globally,” said Jay R. Luly, Ph.D., President and Chief Executive Officer of Enanta Pharmaceuticals. “While we are disappointed with the Court’s decision, we firmly believe in the validity and importance of our patent. Through the appeals process, we remain resolute in defending our intellectual property from infringement.” Enanta emphasized that it does not seek to hinder the availability or distribution of Paxlovid.

Enanta Pharmaceuticals leverages a robust chemistry-driven platform to discover and develop small molecule drugs addressing unmet needs in virology and immunology. The company’s current clinical programs include investigational treatments for respiratory syncytial virus (RSV), while its early-stage immunology pipeline focuses on therapies for inflammatory diseases targeting mechanisms like KIT and STAT6 inhibition.

Enanta’s legacy in protease inhibitor development includes glecaprevir, a key component of the leading chronic hepatitis C virus (HCV) therapy marketed by AbbVie under the brand names MAVYRET® (U.S.) and MAVIRET® (ex-U.S.). Enanta continues to benefit from royalties generated through its collaboration with AbbVie, providing essential funding for its research and development efforts.