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

Giovanni Della Cioppa; Nischal Sahai; Vincent Dodeur; Julie L Dutton; Christopher Moller; Jake S O'Donnell; Andrew Young; Marianne Gillard; Michael Harrison; Rebecca Wolf; Smail Kulenovic; Keith J Chappell; Juana Magdalena; Emmanuel Hanon

doi:10.1016/j.vaccine.2026.128772

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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

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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

Giovanni Della Cioppa, Nischal Sahai, Vincent Dodeur, Julie L Dutton, Christopher Moller, Jake S O'Donnell, Andrew Young, Marianne Gillard, Michael Harrison, Rebecca Wolf, …

Vaccine, Vol.87, pp.1-9

2026

DOI: https://doi.org/10.1016/j.vaccine.2026.128772

PMID: 42224773

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Abstract

Bivalent vaccine

Phase 1 clinical trial, Molecular clamp

Respiratory syncytial virus

hMPV

RSV

Human metapneumovirus

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 -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.

Details

Title: 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
Authors: Giovanni Della Cioppa (Corresponding Author) - Vicebio Ltd (Belgium)
Nischal Sahai (Author) - University of the Sunshine Coast
Vincent Dodeur (Author) - Vicebio Ltd (Belgium)
Julie L Dutton (Author) - The University of Queensland
Christopher Moller (Author) - University of the Sunshine Coast
Jake S O'Donnell (Author) - The University of Queensland
Andrew Young (Author) - The University of Queensland
Marianne Gillard (Author) - The University of Queensland
Michael Harrison (Author) - University of the Sunshine Coast
Rebecca Wolf (Author) - Veritus Research (Australia)
Smail Kulenovic (Author) - Cerba Research (Netherlands)
Keith J Chappell (Author) - The University of Queensland
Juana Magdalena (Author) - Vicebio Ltd (Belgium)
Emmanuel Hanon (Author) - Vicebio Ltd (Belgium)
Publication details: Vaccine, Vol.87, pp.1-9
Publisher: Elsevier Ltd
Date published: 2026
DOI: 10.1016/j.vaccine.2026.128772
ISSN: 1873-2518
PMID: 42224773
Data Availability: The raw data may be available on request
Grant note: This work was supported by Vicebio, Ltd., a Sanofi company, which paid for all costs associated with the the study and the development and the publishing of this manuscript.
Organisation Unit: UniSC Clinical Trials Centre
Language: English
Record Identifier: 991239298802621
Output Type: Journal article

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