Bionor Pharma fails to show a positive effect of its cell-mediated therapeutic HIV-vaccine candidate, Vacc-4x
Bionor Pharma today reported the main findings of an international, randomized, double-blind, placebo-controlled multi-center phase IIb trial designed to test HIV-patients' ability to stay off their ART (Anti Retroviral Therapy) drugs after having been immunized with the company's therapeutic HIV-vaccine candidate, Vacc-4x.
The study did not meet its two primary endpoints. Vacc-4x did not show any clinical effect with regard to number of patients that needed resumption of ART, nor did Vacc-4x show any difference in CD4-counts at the end of the ART-free period compared to placebo.
Bionor Pharma will allow a full analysis of immunological data from the trial. However, the negative clinical result means the company will not continue development of Vacc-4x but will focus on its other vaccine products in pipeline.
In the Vacc-4x phase IIb trial 135 HIV-patients on ART (ITT-population) with CD4-count higher than 400 cells/mm(3), were randomized. 126 of the HIV-patients completed the study (PP-population), of which 88 were immunized and 38 were in the placebo-group. After a 28-week immunization period, all patients were taken off ART and monitored for another 24 weeks. ART was resumed if CD4-count fell below 350 cells/mm(3 )or by more than 50% of the count at the start of the ART-free period, or viral load increased above 300,000 copies/ml.
The primary endpoint was the difference between the two groups with respect to resumption to ART at week 52. There was no statistical significance between the two groups (p=0.89). In the immunized group 65.9% were still off ART-treatment at week 52 as opposed to 71.1% in the placebo group.
The co-primary endpoint compared the percentage change in CD4-count between the two groups from week 28 to resumption of ART, alternatively week 52. The negative difference of 5.7%-points was not statistically significant (p=0.12). The immunized group had an average reduction in CD4-count of 36.0% compared to 30.3% in the placebo group.
"The outcome of this trial is a disappointment", says CEO, Henrik Lund. "A placebo controlled blinded trial has now shown that Vacc-4x does not work. The product will not be developed further".
Bionor Pharma will await analysis of the immunological data before deciding what consequences the results of this study will have on the other vaccine candidates that are based on a similar technology platform as Vacc-4x. However, the company sees no consequences for the further development of Vacc-C5, its humoral HIV-vaccine candidate, which addresses another immune mechanism and is based on a different technology platform.