MONeT: RSV Vaccine Abrysvo Meets Endpoints in Adults 18 to 59 at Increased Risk

Positive topline data were announced from the phase 3 MONeT trial evaluating a single dose of Abrysvo^® (respiratory syncytial virus vaccine) in adults 18 to 59 years of age at risk for developing severe respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD).

The multicenter, randomized, double-blind, placebo-controlled MONeT trial (ClinicalTrials.gov Identifier: NCT05842967) evaluated the immunogenicity and safety of Abrysvo in adults at risk of RSV-associated disease, including those with certain medical conditions (substudy A) and those who are immunocompromised (substudy B). 

Substudy A included 681 adults 18 to 59 years of age with chronic conditions who were randomly assigned 2:1 to receive a single dose of Abrysvo or placebo. Substudy B included approximately 200 immunocompromised adults 18 years of age and older who received 2 doses of Abrysvo (1 month apart).

Results showed Abrysvo met the coprimary immunogenicity endpoints demonstrating noninferior neutralizing responses for RSV-A and RSV-B when compared with responses seen in the phase 3 RENOIR study of Abrysvo in adults 60 years of age and older. Moreover, there was at least a 4-fold increase in neutralizing titers for RSV-A and RSV-B 1 month after receiving Abrysvo compared with prevaccination. The safety profile of Abrysvo was consistent with that observed in other patient populations.

“These encouraging results provide evidence that Abrysvo can help protect adults with increased risk against RSV-associated illness,” said Annaliesa Anderson, PhD, Senior Vice President and Head, Vaccine Research and Development, Pfizer. “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.”

Abrysvo is currently approved for the prevention of LRTD caused by RSV in individuals 60 years of age and older. It is also indicated for active immunization of pregnant individuals at 32 through 36 weeks gestational age for the prevention of LRTD and severe LRTD caused by RSV in infants from birth through 6 months of age.