Pfizer bolsters RSV shot data with positive results in immunocompromised adults

Pfizer recently announced that its respiratory syncytial virus (RSV) vaccine, Abrysvo, has demonstrated efficacy and safety in immunocompromised adults following a single dose. This information comes from the Phase III MONeT study, specifically substudy B, which provided the first data for an RSV vaccine in such a vulnerable group. Annaliesa Anderson, Pfizer's chief scientific officer for vaccine R&D, expressed optimism about the positive results, highlighting Abrysvo's potential to meet a significant unmet need in individuals at heightened risk for severe illness.

The MONeT trial included 203 immunocompromised adults aged 18 and older who are susceptible to severe RSV-associated lower respiratory tract disease (LRTD). The participant group encompassed individuals with non-small-cell lung cancer, those undergoing haemodialysis due to end-stage renal disease, patients receiving active immunomodulator therapy for autoimmune inflammatory disorders, and solid organ transplant recipients.

This study focused on the impact of two doses of Abrysvo, spaced one month apart. Notably, about half of the participants were between the ages of 18 and 59, while the remainder were 60 years or older. The results indicated that a single 120 µg dose of Abrysvo—currently the approved dosage for older adults—elicited a robust neutralising response against both RSV-A and RSV-B strains across all cohorts and age groups. Pfizer plans to share these findings with regulatory authorities and present them at an upcoming medical conference.

Previously, Pfizer announced that the MONeT trial had met its primary objectives. Abrysvo demonstrated a non-inferior immune response compared to that achieved in older adults. In addition to substudy B's focus on immunocompromised adults, substudy A of the trial enrolled 681 participants aged 18 to 59 who are at increased risk for RSV disease, including those with asthma, diabetes, and chronic obstructive pulmonary disease (COPD).

Abrysvo has already gained approval for usage in older adults and to protect infants through maternal immunisation. Additionally, the vaccine is currently being investigated for use in children aged two to under 18 years who are at heightened risk for RSV disease.

In summary, the positive results from the MONeT study support the potential of Abrysvo to provide effective protection against RSV in various at-risk populations, including immunocompromised adults, thereby addressing a critical medical need. Pfizer's next steps involve regulatory consultations and further dissemination of the data to the medical community.