Pfizer has shared positive top-line results from a late-stage trial of its respiratory syncytial virus (RSV) vaccine in adults aged 18 to 59 years who are at an increased risk of developing severe RSV-associated lower respiratory tract disease (LRTD).
RSV is a common contagious virus characterised by several mild, cold-like symptoms. Although most people recover within a week or two, the virus can cause severe illness in certain groups, including older adults, infants and those with certain underlying chronic conditions.
Pfizer’s Abrysvo is already approved in major markets, including the US and EU, to protect older adults against RSV as well as infants through maternal immunisation. However, there are currently no vaccines approved for use in adults aged 18 to 59 years.
The ongoing MONeT study has been evaluating the immunogenicity and safety of Abrysvo in higher-risk adults in this age population, including those with asthma, diabetes and chronic obstructive pulmonary disease.
The trial achieved its co-primary immunogenicity endpoints and primary safety endpoint, Pfizer said, with patients demonstrating RSV-A and RSV-B subgroup neutralising responses that were non-inferior to the responses seen in the phase 3 RENOIR study of the vaccine in adults aged 60 years and older.
Those enrolled in MONeT also achieved at least a four-fold increase in serum neutralising titres for RSV-A and RSV-B one month after receiving Abrysvo compared to pre-vaccination, and safety findings were consistent with those from previous investigations of the vaccine in other populations.
Pfizer said it intends to submit the data to regulatory agencies and request the expansion of the approved age group to 18 years and older.
Annaliesa Anderson, senior vice president and head, vaccine research and development at Pfizer, said: “These encouraging results provide evidence that Abrysvo can help protect adults with increased risk against RSV-associated illness.
“We are excited to address a significant unmet need, pending regulatory authority approval, as Abrysvo has the potential to become the first and only RSV vaccine for adults 18 years and older.”
The readout comes just over a month after Pfizer shared new results from RENOIR showing that Abrysvo maintained consistently high protective efficacy for both RSV A and RSV B disease through two seasons after a single dose.