Experimental HIV Vaccine Induces Robust Immune Response in Humans

An experimental HIV-1 vaccine regimen, mosaic adenovirus serotype 26 (Ad26) was well-tolerated and produced immune responses against HIV in humans and rhesus monkeys, according to findings from a phase 1/2a clinical trial published in the Lancet.

In the APPROACH trial, 393 individuals with a low risk of HIV were recruited to receive either 1 of 7 vaccine combinations or a placebo; they were given 4 vaccinations over 48 weeks. To stimulate an initial immune response, each participant received an injection of Ad26.Mos.HIV at the advent of the study and 12 weeks later. Two additional vaccinations were given at week 24 and week 48 using combinations of Ad26.Mos.HIV or a different vaccine component referred to as modified Vaccinia Ankara (MVA) with or without 2 different doses of clade C HIV gp140 protein. The researchers found that all vaccine regimens were well-tolerated and were able to induce anti-HIV immune responses in healthy individuals. Similar systemic reactions were reported in all groups included in the trial.

In a parallel study, the efficacy of the candidate was assessed in 72 rhesus monkeys with simian-human immunodeficiency virus (SHIV) a virus similar to HIV that affects monkeys. The Ad26/Ad26 plus gp140 vaccine candidate induced the greatest immune responses in humans and provided complete protection in two-thirds of the monkeys after six challenges.

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