GSK plc announced that the US Food and Drug Administration (FDA) has approved Arexvy (Respiratory Syncytial Virus (RSV) Vaccine, Adjuvanted) for the prevention of RSV lower respiratory tract disease (LRTD) in adults 50 through 59 years of age who are at increased risk. In the US, the vaccine is currently approved for use in adults aged 60 and older and recommended by CDC/ACIP using shared clinical decision-making. A systematic review of studies in the US showed that RSV is estimated to cause 42,000 hospitalisations each year in adults aged 50-64 years old.[2] Adults with underlying medical conditions, such as chronic obstructive pulmonary disease (COPD), asthma, heart failure and diabetes are at increased risk for severe consequences from an RSV infection compared to those without these conditions.

RSV can exacerbate these conditions and lead to pneumonia, hospitalisation or death. GSK has also filed regulatory submissions to extend the use of its RSV vaccine to adults aged 50-59 at increased risk in Europe, Japan and other geographies with regulatory decisions undergoing review. Trials evaluating the immunogenicity and safety of the vaccine in adults aged 18-49 at increased risk and immunocompromised adults aged 18 and over are expected to read out in second half 2024.

Respiratory Syncytial Virus Vaccine, Adjuvanted, contains recombinant RSV glycoprotein F stabilised in the prefusion conformation (RSVPreF3). This antigen is combined with GSK's proprietary AS01E adjuvant. In May 2023, the FDA approved GSK's RSV vaccine for the prevention of lower respiratory tract disease (LRTD) caused by respiratory syncytial virus (RSV) in individuals 60 years of age and older.

The use of this vaccine should be in accordance with official recommendations. As with any vaccine, a protective immune response may not be elicited in all vaccinees. The vaccine has also been approved for the prevention of RSV-LRTD in individuals 60 years of age and older in over 40 countries, including Europe, Japan and US.

Regulatory reviews in multiple countries are ongoing. The proposed trade name remains subject to regulatory approval in other markets. The GSK proprietary AS01 adjuvant system contains STIMULON QS-21 adjuvant licensed from Antigenics Inc, a wholly owned subsidiary of Agenus Inc. STIMULON is a trademark of SaponiQx Inc., a subsidiary of Agenus.

NCT05590403 is a phase III, placebo-controlled, observer-blind, randomised, multi-country immunogenicity trial to evaluate the non-inferiority of the immune response and evaluate safety in participants aged 50 to 59, including those at increased risk for RSV-LRTD compared to older adults aged 60 years and above after a single dose of GSK's RSV vaccine. The study assessed the immune response in participants aged 50 to 59 with pre-defined stable chronic diseases leading to an increased risk for RSV disease (n=570). Immune responses in a broader group of participants aged 50-59 years without these pre-defined chronic diseases (n=570) were also evaluated compared to adults aged 60 and older.

The trial's primary endpoints were RSV-A and RSV-B neutralisation titres of both groups at one month after the vaccine administration compared to adults aged 60 and older. There were also safety and immunogenicity secondary and tertiary endpoints. Safety and reactogenicity data were consistent with results from the initial AReSVi-006 data read out.

The most common local adverse event was pain. The most common systematic adverse events were myalgia, fatigue and headache, which were largely transient and mild to moderate in intensity. Results from this trial have been presented at the ACIP meeting of October 2023 and at ReSVinet in February 2024, and have been submitted for peer-reviewed publication.

The data are being submitted to other regulators to support potential label expansions. RSV is a common contagious virus affecting the lungs and breathing passages. Adults can be at increased risk for RSV disease due to comorbidities, immune compromised status, or advanced age.

RSV can exacerbate conditions, including COPD, asthma, and chronic heart failure and can lead to severe outcomes, such as pneumonia, hospitalisation, and death. Each year, RSV is estimated to cause approximately 177,000 hospitalisations in adults 65 years and older6 and 42,000 in adults aged 50-64 years old in the US.