Agenus Herpes Vax Posts Solid Results

Agenus Inc. has posted statistically significant top-line results from its Phase II trial of HerpV, a recombinant “off-the-shelf” therapeutic vaccine candidate for the treatment of patients with herpes simplex virus-2 (HSV-2). HerpV contains a defined mixture of peptides representing HSV-2 antigens plus Agenus’ QS-21 Stimulon adjuvant.

The study tested the biological efficacy of HerpV measuring genital viral shedding 45 days before and after three injections of HerpV. The primary analysis, which looked at viral shedding after the initial three injections, shows that subjects who received HerpV had a statistically significant reduction in viral shedding. These results suggest a 15% reduction in viral shedding after the initial treatment period before the administration of the booster injection. The results also demonstrate a reduction in viral load of 34%. Placebo patients showed no reduction compared to baseline in either parameter. Notably, patients were not on any antiviral treatments during their swabbing period. The initial data support that vaccination with HerpV has a real, measurable biological effect lowering the active shedding of the virus.

The majority of subjects in the study have received a booster injection of HerpV that was given six months after the first vaccination followed by determination of genital viral shedding for an additional 45-day period. Post-booster viral shedding results, along with immune response data, are anticipated in the 1H14.

The HerpV Phase II study design was defined by key opinion leaders in the field. Experts in HSV-2 clinical research believe that a reduction in viral shedding is an important surrogate for clinical benefit in the form of reduction in recurrent outbreaks. A total of 80 subjects with a history of one to nine herpes recurrences within the prior 12 months were randomized into the trial and 70 subjects received the active treatment, HerpV and QS-21 Stimulon, and 10 subjects received placebo.