Material Event (Form 8-K)

Item 8.01 Other Events.

As previously disclosed by Enanta Pharmaceuticals, Inc. (the "Company"), the Company filed a notice of appeal with the United States Court of Appeals for the Federal Circuit (the "Federal Circuit") relating to its suit against Pfizer Inc. 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). On June 23, 2026, the Federal Circuit affirmed the December 2024 summary judgment decision of the United States District Court for the District of Massachusetts and ruled that the claims of the '953 Patent were invalid.