Immune Responses to Arexvy in Adults aged 50 to 59 Years Noninferior to those in Adults aged 60 Years and Older

The adjuvanted respiratory syncytial virus (RSV) vaccine (Arexvy; GSK) was associated with non-inferior immune responses in adults aged 50 to 59 years compared to those aged 60 years and older, including those in the younger age group with underlying medical conditions placing them at increased risk for RSV lower respiratory tract disease (LRTD).

The preliminary findings, announced recently by GSK, come from a multicountry immunogenicity trial that is also evaluating the safety of the vaccine in adults aged 50 to 59 years. Currently the adjuvanted RSV vaccine is approved in the US for adults aged 60 years and older. The results of the study were presented at the CDC Advisory Committee on Immunization Practices meeting on October 25, 2023.

“This trial reinforces our confidence in our RSV vaccine’s ability to help protect adults aged 50 to 59 at increased risk for RSV-LRTD. We will submit these data for regulatory review as quickly as possible with the goal of offering adults in this age group the option of a vaccine for the first time,” Tony Wood, PhD, chief scientific officer at GSK, said in the announcement.

The randomized, placebo-controlled study aimed to evaluate the non-inferiority of the immune response to Arexvy in adults in the 50- to 59-year age range who have an increased risk of RSV-LRTD compared to those aged 60 years and above after a single dose of the RSV vaccine.

The study assessed the immune responses of 570 individuals aged 50 to 59 years with predefined stable chronic diseases that increased the risk of RSV-LRTD including chronic pulmonary disease, chronic cardiovascular disease, diabetes, chronic kidney disease, or chronic liver disease. Researchers also evaluated immune response among 570 participants aged 50 to 59 years without underlying medical conditions. Immune response in both groups was compared to the response observed in adults aged 60 years and older. There were approximately 1520 participants enrolled from 8 countries.

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The study met its co-primary endpoints of eliciting immune responses among the cohort aged 50 to 59 years at high risk for RSV LRTD as well as for the same-aged group not at increased risk that was noninferior to that observed in those aged 60 years and older, reported GSK.

The investigators found safety and reactogenicity data among all participants in the trial consistent with those from the initial phase 3 program. Pain at the injection site was reported as the most common local adverse event (AE); the most common systemic AEs, fatigue, and headache, were reported as mild and transient.

In addition to the phase 3 study’s primary endpoints, RSV-A and RSV-B neutralization titers of both groups of 50- to 59-year-olds at 1-month post-vaccination compared to adults aged 60 and older, there were also safety and immunogenicity secondary and tertiary endpoints. The trial is ongoing to collect further immune data at 6 and 12 months after vaccine administration.

Presentation of the study’s final results is planned for an upcoming medical conference. Data also will be submitted to a peer-reviewed publication and to the FDA and other regulators for a potential label expansion.

Source: New data for Arexvy, GSK’s RSV vaccine, show potential to help protect adults aged 50 to 59 at increased risk for RSV disease. News release. GSK. October 25, 2023. Accessed October 30, 2023. https://www.gsk.com/en-gb/media/press-releases/new-data-for-arexvy-show-potential-to-help-protect-adults-aged-50-to-59/