Enanta Pharmaceuticals, Inc.

WATERTOWN, Mass.--(BUSINESS WIRE)--Sep. 3, 2025-- Enanta Pharmaceuticals, Inc. (NASDAQ:ENTA) today announced the passing of its beloved and respected longtime Chief Financial and Administrative Officer Paul J. Mellett Jr. “The entire Enanta team mourns the loss of Paul, our colleague and friend,” said Jay R. Luly, Ph.D., President and Chief Executive Officer of Enanta Pharmaceuticals. “Since joining the Company more than two decades ago, Paul’s leadership and generosity of spirit have been at the core of Enanta. Paul’s dedication to the Company was complete and steadfast. He carried himself with humility, led with compassion, and inspired trust, and his relationships were authentic, rich, and fun.” Dr. Luly added, “Paul joined Enanta in September 2003 and established the finance department, bringing critical expertise that shaped the Company’s growth and success. He led Enanta’s Initial Public Offering in 2013 and was instrumental in advancing the Company’s early partnerships, including the strategic 2006 research and development collaboration with Abbott, now AbbVie, that resulted in commercialization of VIEKIRA PAK® and MAVYRET®/MAVIRET® – two medications for the treatment of chronic hepatitis C virus infection that have cured more than one million patients globally. Paul’s legacy will forever be woven into the fabric of Enanta, and his friendship will be missed by all of us. On behalf of Enanta, and the Board of Directors, we extend our deepest, heartfelt condolences to his family and friends.” Paul’s successful career spanned almost 50 years. Prior to joining Enanta, he was Senior Vice President and Chief Financial Officer of Essential Therapeutics. Before that, Paul was the Chief Financial Officer and Vice President of Administration at GelTex Pharmaceuticals, Inc., a publicly held biotechnology company that was acquired by Genzyme Corporation in December 2000. Paul also served as Chief Financial Officer of Marshall Contractors, a construction management firm specializing in the pharmaceutical, biotechnology and semiconductor industries. Earlier in his career, Paul was employed with Deloitte & Touche LLP, a public accounting firm, where he served as Audit Partner. He graduated from Boston College. He also graduated from Xaverian Brothers High School where he served proudly on its board for 12 years. Paul also dedicated his time as a board member of Norwood Hospital and Big Brothers Big Sisters of Boston, demonstrating his commitment to service. As previously announced, Harry R. Trout, III, and Kathleen S. Capps, CPA, have been appointed as the Company’s principal financial officer and principal accounting officer, respectively, in each case on an interim basis. 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 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. View source version on businesswire.com: https://www.businesswire.com/news/home/20250903190271/en/ Media and Investors Contact: Jennifer Viera 617-744-3848 jviera@enanta.com Source: Enanta Pharmaceuticals, Inc.

Enanta Pharmaceuticals is escalating its patent battle over Pfizer’s Covid-19 antiviral Paxlovid. The Watertown, MA-based drugmaker announced Wednesday that it filed suit against Pfizer in the Unified Patent Court of the European Union. Enanta alleges that Paxlovid infringes its ‘265 patent based on a 2020 application that describes “coronavirus protease inhibitors invented by Enanta scientists.” Pfizer beat a similar challenge brought by Enanta in federal court in Massachusetts, but Enanta filed an appeal in February. In Europe, Enanta expects a hearing within the court’s 12-month target, and a decision “within weeks thereafter,” the company said in a news release. A Pfizer spokesperson told Endpoints News on Wednesday that the company is “confident in our IP surrounding Paxlovid and will respond in due course in court.” Pfizer’s BioNTech-partnered Covid vaccine has also been at the center of patent litigation, including an ongoing case in Massachusetts federal court brought by Moderna. Earlier this month , a UK appeals court upheld the validity of a key Moderna patent, marking a loss for Pfizer and BioNTech in the long-running legal fight among the three companies. At the time, Pfizer and BioNTech said they planned to appeal the UK ruling.

Paxlovid has risen to become to one of Pfizer’s best-selling drugs despite reduced demand for Covid-19-related treatment. Credit: Lady Jiff / Shutterstock.com. If you don’t succeed at first, try again – in separate regions. That’s the motto Enanta Pharmaceuticals is following, at least, after disclosing it has sued Pfizer in Europe over a patent infringement relating to Covid-19 treatment pill Paxlovid (nirmatrelvir/ritonavir). In June 2022, Enanta filed a lawsuit against Pfizer in a US district court in Massachusetts, claiming that the big pharma company infringed on a patent describing protease inhibitors invented by its scientists. Enanta has now followed that up with another filing in Europe, making the same accusation. Since being emergency authorised in 2021, anti-viral Paxlovid has generated Pfizer more than $26bn in global revenue. This includes a staggering $18.9bn in 2022 when Covid-19 cases were still prevalent. Despite waning demand for Covid-19 treatments, the pill still brought in $1.2bn in 2024, buoyed by government orders. However, Enanta – known for co-developing hepatitis C virus treatment glecaprevir/pibrentasvir with AbbVie – believes Pfizer designed Paxlovid via unlawful means. The US biotech stated it is “seeking a determination of liability for use and infringement of European Patent No. EP 4 051 265 (the ’265 Patent) in the manufacture, use and sale of Pfizer’s Covid-19 antiviral, Paxlovid”. In an emailed statement to Pharmaceutical Technology, a Pfizer spokesperson said: “We are confident in our intellectual property (IP) surrounding Paxlovid and will respond in due course in court.” GlobalData Strategic Intelligence US Tariffs are shifting - will you react or anticipate? Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis. By GlobalData Learn more about Strategic Intelligence The lawsuit, filed in the European Union’s (EU) Unified Patent Court (UPC), targets Pfizer’s commercial activity in the 18 countries of the EU. The company confirmed the ’265 patent in question is the European counterpart of US patent number 11,358,953 (the ’953 Patent) that is the centre of the US lawsuit. Although it is technically ongoing, Enanta’s US lawsuit hit a major roadblock. In December 2024, a federal judge in Massachusetts sided with Pfizer, granting that the ‘953 patent is invalid. Enanta confirmed at the time it would appeal the decision, adding it “believes strongly in the merits of our case”. Pfizer reported strong Q2 2025 results this month, bucking a tepid earnings window that gripped the wider pharma industry. Sales for the Paxlovid grew 71% while the Covid-19 vaccine Comirnaty revenue surged 95%. However, the legal challenge posed by Enanta marks the second issue Pfizer has had to firefight this week. The big pharma company reported a Phase III trial failure for a sickle cell disease candidate purchased as part of a $5.4bn takeover of Global Blood Therapeutics in 2022. Pharmaceutical Technology Excellence Awards - The Benefits of Entering Gain the recognition you deserve! The Pharmaceutical Technology Excellence Awards celebrate innovation, leadership, and impact. By entering, you showcase your achievements, elevate your industry profile, and position yourself among top leaders driving pharmaceutical advancements. Don’t miss your chance to stand out—submit your entry today! Nominate Now