Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection (LRTI) among infants and young children, resulting in annual epidemics in Japan. Children with congenital or acquired immunodeficiencies, transplant recipients, and those receiving immunosuppressive therapy are at increased risk for severe RSV-associated LRTI with prolonged viral shedding and higher viral loads, resulting in prolonged hospitalizations, admissions to the intensive care unit (ICU), and the need for mechanical ventilation. Palivizumab (Synagis®) is the only approved agent for RSV prophylaxis, and its half-life (t1/2) is approximately 1 month, infants and young children need to receive monthly intramuscular doses of palivizumab throughout the RSV season to maintain protection. This constitutes a significant burden on healthcare providers as well as the infants/children and their families.~Nirsevimab may provide a cost-effective opportunity to protect all infants from RSV disease based on an improvement in potency and the extended t1/2 that is expected to support once-per-RSV-season dosing.
Study D5290C00008 is a Phase 2, open-label, uncontrolled, single-dose study to evaluate the safety and tolerability, pharmacokinetic(s) (PK), occurrence of antidrug antibody (ADA), and efficacy of nirsevimab in immunocompromised children who are ≤ 24 months of age at the time of dose administration. Approximately 100 subjects will be enrolled. Subjects will be followed for approximately 1 year after dose administration.