A phase 3 HIV vaccine efficacy trial at multiple clinical research sites in North America, South America and Europe will open for enrolment later this year.
The HPX3002/HVTN 706 trial (Mosaico) will enrol 3,800 HIV-negative men and transgender people aged 18 to 60 years who have sex with men and/or transgender people. It will assess whether an investigational vaccine regimen designed to induce immune responses against a variety of global HIV strains can safely and effectively prevent HIV acquisition in this population.
All Mosaico participants will be offered a comprehensive HIV prevention package, including access to pre-exposure prophylaxis (PrEP) and will be randomly assigned to receive either the investigational vaccine regimen or a placebo. Vaccinations will be given at four time points over one year.
The experimental regimen comprises four doses of Ad26.Mos4.HIV, a vaccine candidate that uses an engineered common-cold virus (adenovirus serotype 26, or Ad26) to deliver four mosaic immunogens.
The final two vaccinations will be given together with a bivalent HIV envelope protein formulation, combining clade C gp140 and mosaic gp140 envelope proteins, adjuvanted by aluminium phosphate to boost immune responses.
A complementary phase 2b study in women called HPX2008/HVTN 705 (Imbokodo), launched in 2017 in five southern African countries, is ongoing.