GEN-003 therapeutic vaccine reduces genital lesions in phase 2b trial

Data from a phase 2b trial examining the safety and efficacy of the therapeutic vaccine GEN-003 for the treatment of genital herpes showed that three doses of treatment reduced the rate of genital lesions as well as the number and duration of recurrences 6 months after administration compared with placebo, according to a press release.

“These data cement a compelling profile for GEN-003 built over 3 clinical studies in which we have dosed more than 500 patients,” Chip Clark, president and CEO of Genocea, said during a conference call. “These trials show that GEN-003 has a durable and meaningful impact on genital herpes clinical disease and significantly reduces viral shedding — the driver of both genital lesions and disease transmission — and has the promise of maintenance dosing no more frequently than once yearly and has demonstrated a safety profile appropriate for its therapeutic setting.”

GEN-003 is a T-cell-directed immunotherapy that is designed to produce T-cell and B-cell immune responses against genital herpes, according to the release. The vaccine contains antigens ICP4 and gD2 and is combined with the novel adjuvant Matrix-M (Novavax).

The phase 2b trial included 131 patients from nine institutions in the United States. Researchers randomly assigned patients to receive three injections at 21-day intervals of either 60 µg per antigen/50 µg of adjuvant (n = 43), 60 µg per antigen/75 µg of adjuvant (n = 44), or placebo. In September, Genocea announced that the trial reached its primary endpoint, with the 60 µg per antigen/50 µg of adjuvant dose of GEN-003 demonstrating a 40% reduction in the rate of viral shedding compared with baseline and placebo.

According to the release, the new data continue to support the use of the 60 µg per antigen/50 µg of adjuvant dose, which was associated with a 41% reduction in the percentage of days with genital lesions vs. placebo 6 months after dosing (4.5% vs. 7.9%; P < .05). The rate of genital lesions also was reduced in those who received 60 µg per antigen/75 µg of adjuvant (4.6%) compared with placebo.

In other results, the mean duration of recurrences was 3.3% among those who received 60 µg per antigen/50 µg of adjuvant and 4.3% among those who received 60 µg per antigen/75 µg of adjuvant vs. 4.8% who received placebo. The mean number of recurrences over 6 months was 2.1% and 1.9% among those who received 60 µg per antigen/50 µg of adjuvant and 60 µg per antigen/75 µg of adjuvant vs. 2.7% who received placebo.

Genocea reported that the number of discontinuations due to adverse events was low and similar across the dose groups and placebo. There was no grade 4 reactogenicity or other related serious adverse events. The patients will continue to be monitored until 12 months after the last dose.

“We are very pleased to have demonstrated such a powerful impact on genital herpes clinical disease in this trial, supporting the groundbreaking potential of GEN-003 to be the first-ever therapeutic vaccine for a chronic infection and the first advance in the treatment of genital herpes in more than 20 years,” Clark said in the release. “We look forward to meeting with the FDA in the first quarter of 2017 and to commencing our GEN-003 Phase 3 program in the fourth quarter of 2017.” – by Stephanie Viguers

Disclosure: Clark is an employee of Genocea.