NCT06556147

A Study of RSV-HMPV Bivalent Vaccine VXB-241 in Older Adults

A Phase 1 Randomized, Placebo- and Active-controlled, Observer-blind Study in Older Adults With Run-in in Young Adults to Evaluate the Safety, Reactogenicity, and Immunogenicity of Four Dose Levels of VXB-241, A Molecular Clamp Stabilized Prefusion F Glycoprotein Subunit Bivalent Vaccine Candidate for the Prevention of Lower Respiratory Tract Disease Caused by Respiratory Syncytial Virus (RSV) And Human Metapneumovirus (HMPV)

• Status: Active Not Recruiting
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 144 (actual)
• Sponsor: Vicebio Australia Proprietary Limited · Industry
• Sex: All
• Age: 18 Years – 83 Years
• Healthy volunteers: Accepted

Summary

The main purposes of this study are to assess the safety, reactogenicity and immunogenicity of 4 dose levels of the bivalent combination Respiratory Syncytial Virus (RSV) / human Metapneumovirus (hMPV) vaccine candidate VXB-241 when administered as a single-dose regimen to healthy adults 60 to 83 years of age, and to assess the impact of revaccination approximately 1 year later.

Detailed description

This is a multi-center study in older adults with run-in in younger adults to evaluate the safety, reactogenicity, and immunogenicity of 4 dose levels of VXB-241. The total planned sample size is 136 randomized participants, composed of 16 younger adults 18 to 40 years of age and 120 older adults 60 to 83 years of age who are in good health, which allows for many chronic conditions, if well controlled and compatible with self-sufficiency in self-care and daily living activities. Recruitment will be in 2 stages: * Stage 1 (Sequential Cohort Stage, N=32). Four cohorts (Cohorts 1 to 4), each of 8 participants, will be enrolled sequentially. In each cohort, 4 younger adults will be enrolled first, followed by 4 older adults. Younger and older adult participants will be randomized with 3:1 ratio to VXB-241 at increasing dose (60 microgram (mcg), 120 mcg, 240 mcg, 480 mcg in Cohorts 1 to 4, respectively) or Placebo. A Safety Monitoring Committee will make recommendations on escalation from one cohort to the next and from Stage 1 to Stage 2 based on safety and reactogenicity data collected over 1 week after investigational medicinal product (IMP) dosing. * Stage 2 (Concurrent Group Stage, N=104). Older adult participants will be randomized concurrently with unequal randomization to 1 of 6 treatment groups: VXB-241 60 mcg (Group 1a), VXB-241 120 mcg (1b), VXB-241 240 mcg (1c), VXB-241 480 mcg (1d), commercial RSV vaccine Arexvy (2a), Placebo (3a). The planned total sample size of each treatment group, combining Stage 1 and Stage 2, is N=20. The overall planned duration of the study is approximately 6 months for younger adult participants and approximately 2 years for older adult participants. At the end of the 1st year, older adult participants will receive a second IMP injection (revaccination): participants who received VXB-241 (at any dose) will be assigned 1:1 to revaccination with VXB-241 (Group 1e) or Placebo (1f); participants who received Arexvy will be revaccinated with placebo (2b); participants who received Placebo will be revaccinated with VXB-241 (3b). The dose of VXB-241 for revaccination will be 240 mcg (RSV preF 120 mcg + HMPV preF 120 mcg) (based on 1 month post 1st IMP injection results).

Conditions

• Healthy Volunteers

Interventions

Type	Name	Description
BIOLOGICAL	VXB-241 60 mcg (Low Dose)	VXB-241 low dose, single, IM injection.
BIOLOGICAL	VXB-241 120 mcg (Medium Dose)	VXB-241 medium dose, single, IM injection.
BIOLOGICAL	VXB-241 240 mcg (Medium-high Dose)	VXB-241 medium-high dose, single, IM injection.
BIOLOGICAL	VXB-241 480 mcg (High Dose)	VXB-241 high dose, single, IM injection.
BIOLOGICAL	VXB-241 240 mcg	VXB-241 240 mcg (RSV preF 120 mcg + hMPV preF 120 mcg) (based on 1 month post 1st IMP injection results) single, IM injection.
OTHER	Placebo	Placebo, single, IM injection.
BIOLOGICAL	Arexvy 120 mcg	Arexvy 120 mcg, single, IM injection.

Timeline

• Start date: 2024-08-13
• Primary completion: 2025-02-14
• Completion: 2027-05-01
• First posted: 2024-08-15
• Last updated: 2025-10-01

Locations

4 sites across 1 country: Australia