Enanta Pharmaceuticals Inc.

B USINESS BUSINESS Overview We are a biotechnology company that uses our robust, chemistry-driven approach and drug discovery capabilities to discover and develop small molecule drugs for virology and immunology indications. Virology: We discovered glecaprevir, the second of two antiviral protease inhibitors developed through our collaboration with AbbVie for the treatment of acute or chronic infection with hepatitis C virus, or HCV. Glecaprevir is co-formulated as part of AbbVie’s leading brand of direct-acting antiviral, or DAA, combination treatment for HCV, which has been marketed under the tradenames MAVYRET (U.S.) and MAVIRET (ex-U.S.) (glecaprevir/pibrentasvir) since 2017 for the treatment of chronic HCV. MAVYRET was also approved as the first and only treatment for acute HCV infection in June 2025. Our active development programs in virology are focused on respiratory syncytial virus, or RSV, the most common cause of bronchiolitis and pneumonia and a leading cause of U.S. hospitalization in young children and a significant cause of respiratory illness in older adults. Populations at high risk for severe RSV infection include infants and young children, adults older than 65 years of age, and those with comorbidities such as chronic heart or lung disease. Recent CDC estimates suggest a significant RSV burden in the U.S., with up to 6.5 million outpatient visits, 350,000 hospitalizations and 23,000 deaths annually.