What question did this study set out to answer?

This trial aims to evaluate the safety, immunogenicity, and optimal dosing of the VXB-241 vaccine in older adults.

June 3, 2026Vaccine0 citationsOpen Access

Safety, immunogenicity, and dose ranging of a bivalent respiratory syncytial virus and human metapneumovirus glycoprotein F-molecular clamp vaccine candidate in older adults: 1-month interim analysis of an ongoing randomised, observer-blind, placebo- and active-controlled, phase 1 trial

GCGiovanni Della CioppaAsahi Glass (Belgium)NSNischal SahaiUniversity of the Sunshine Coast VDVincent DodeurCoatings Research Institute

Key Points

This trial aims to evaluate the safety, immunogenicity, and optimal dosing of the VXB-241 vaccine in older adults.
Ongoing randomized, observer-blind, placebo- and active-controlled trial in older adults aged 60–83 years.
Participants received VXB-241 at varying doses or the active control RSVPreF3, with assessments at 1 month after vaccination.
Safety and immunogenicity outcomes were evaluated including adverse events and neutralising antibody titres.
Solicited adverse events occurred in 23.8% (placebo) and 76.2% (RSVPreF3), with VXB-241 ranging from 35.0% to 59.1%, primarily mild.
At month 1, neutralising antibody titres for RSV and hMPV in all active treatment arms were significantly higher than placebo.
The 240 μg dose of VXB-241 yielded higher geometric mean fold increases in neutralising antibodies than RSVPreF3 across multiple strains.

Abstract

Background Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are important causes of acute respiratory tract disease in older adults. Multipathogen vaccines in ready-to-use liquid formulations are needed. VXB-241 is a recombinant RSV-hMPV unadjuvanted fully liquid vaccine candidate. Methods This ongoing first-in-human randomised, placebo- and RSV vaccine active-controlled, observer-blind, dose-ranging trial is being conducted in older adults aged 60–83 years preceded by a few sentinel younger adults aged 18–40 years. On day 1, older adults were randomised to receive one of six intramuscular treatments: VXB-241 at 60 μg (30 μg RSV preF +30 μg hMPV preF), 120 μg (60 + 60), 240 μg (120 + 120), or 480 μg (240 + 240), the licensed AS01 E -adjuvanted RSV vaccine (Arexvy™/RSVPreF3, GSK), or placebo. We report 1-month interim safety and immunogenicity results. Results A total of 270 older adults were screened; 128 were randomised and completed the month-1 visit. Solicited adverse events occurred in 23.8% of placebo, 76.2% of RSVPreF3, and 35.0%–59.1% of VXB-241 recipients, with no dose-response effect among VXB-241 recipients, except at the highest dose level. Most reactions were mild and transient. Most unsolicited adverse events were unrelated to treatment. No safety signal was detected. At month 1, RSV-A, RSV-B, hMPV-A and hMPV-B neutralising antibody titres were higher than placebo in all active treatment arms. At the 240 μg VXB-241 dose level, geometric mean fold increases were 15.06 for RSV-A and 8.07 for RSV-B versus 10.81 for RSV-A and 4.91 for RSV-B after RSVPreF3 injection, and 7.50 for hMPV-A and 6.56 for hMPV-B, with negligible increases after RSVPreF3 injection. Conclusions VXB-241 showed a clinically acceptable safety and reactogenicity profile and elicited strong neutralising immune responses against RSV and hMPV in older adults. Neutralising immune responses against RSV-A and RSV-B by VXB-241 were at least as good as those obtained with the licensed adjuvanted RSVPreF3 active control.

Ask AI

Helpful

Bookmark

View Full Paper