French biopharmaceutical firm InnaVirVax has started a Phase II clinical trial evaluating the therapeutic properties of the VAC-3S vaccine when combined with standard antiretroviral therapy (ART) in the course of HIV-1 infection.
Three VAC-3S doses will be compared in the randomised, double-blind, placebo-controlled Phase II trial, which will see around 90 patients studied in France, Germany and Spain.
The trial is carried out among HIV-1 infected adults with viral load less than or equal to 50 copies/mm3 treated with ART, whose CD4+ T-cell count at screening is between 200 and 500 cells/mm3.
Initially a three-month base vaccination will be carried out, followed by 3-maintenance injections carried out in two of three dosage groups and a six-month follow-up period.
The primary objective of the trial is to evaluate antibody response to the VAC-3S vaccine, which has been constructed to induce a humoral immune response against a highly conserved region of the gp41envelope protein of the HIV-1 known as 3S.
VAC-3S that complements ART acts on the immune system through CD4+ T-cells, a major factor responsible for progression of the disease during HIV-1 infection.
The data available from human group studies and non-human primate models indicate that anti-3S antibodies are related to an increase in CD4+ T cells and a decrease of HIV viral reservoirs, as well as HIV inflammatory biomarkers.
VAC-3S includes three distinct but covalently linked parts so as to optimise production of an immune response.
The secondary objectives of the trial include overall general and local tolerance as well as clinical safety, comprehensive assessment of the immunological endpoints, inflammatory biomarkers, HIV reservoir and also identify the vaccine's immunogenic characteristics.
A Phase I dose escalation trial of VAC-3S conducted previously in 33 patients living with HIV whose CD4 T-lymphocyte levels were higher than 200mm³ and who were on ART, showed safety and offered data for dose selection.