ARTICLE | Clinical News

Vacc-4x: Final Phase IIb data

February 20, 2012 8:00 AM UTC

Final data from a double-blind, international Phase IIb trial in 81 evaluable HIV-infected patients showed that Vacc-4x significantly reduced median viral load set point at week 52 by 64% vs. placebo (22,300 vs. 61,900 copies/mL, p=0.04). Viral load set point is the average of the last 2 viral load measurements before the end of the study. The trial enrolled 136 patients. Patients on ART with a CD4 count >400 cells/mm 3 received Vacc-4x or placebo for a 28-week immunization period. At week 28, all patients stopped ART and were monitored for 24 weeks. ART was resumed if CD4 count fell below 350 cells/mm 3 or by >50% of the count at the start of the ART-free period, or if a patients' viral load increased to >300,000 copies/mL.

In November 2010, Bionor reversed a previous decision to discontinue development of Vacc-4x after additional data from the trial showed that the vaccine met the secondary endpoint of significantly reducing viral load from baseline during the study period in the whole patient population (p=0.028) and in a subset of patients that did not resume ART vs. placebo (p=0.0012) (see BioCentury, Dec. 13, 2010). In October 2010, Bionor reported that Vacc-4x missed the co-primary endpoints of significantly reducing the proportion of patients requiring resumption of ART at week 52 vs. placebo (65.9% vs. 71.1%, p=0.89), and of the percent change in CD4 count between treatment groups from week 28 to resumption of ART (36% vs. 30.3% reductions, p=0.12). ...