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New data support efficacy of GEN-003 vaccine against genital lesions
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Recent 12-month data from a phase 2b trial demonstrated that Genocea Biosciences’ lead GEN-003 vaccine regimen reduced the median rate of genital lesions by nearly 50% compared with placebo among patients with herpes simplex virus-2.
The results support 24-month data from a phase 2 trial that evaluated six various dosing regimens of GEN-003, as well as 6-month data from the ongoing phase 2b trial comparing the two most promising dosing regimens with placebo.
“We believe these data further solidify the strong clinical profile for GEN-003, which could provide durable, convenient efficacy to a large and, we believe, highly dissatisfied patient population and serve as a cornerstone treatment of this burdensome disease,” Chip Clark, president and CEO of Genocea, said in a press release.
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).
Researchers from the phase 2b trial randomly assigned 131 patients from nine U.S. institutions to receive either 60 µg per antigen/50 µg of adjuvant (n = 43), 60 µg per antigen/75 µg of adjuvant (n = 44), or placebo. Each participant received three injections administered at 21-day intervals.
“The goals of the trial were to evaluate the phase 3-ready formulation of GEN-003 and to find a dose to move forward into the phase 3 program,” Seth Hetherington, MD, chief medical officer for Genocea Biosciences, said during a conference call. “Data in this trial were important in helping us to define our primary phase 3 endpoint, which we have discussed with the FDA at our End of the Phase 2 Meeting and expect to be the reduction of the median genital lesion rate vs. placebo over the 12 months following the series of three doses 21 days apart.”
In September, Genocea announced that the phase 2b 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. At 6 months, the 60 µg per antigen/50 µg of adjuvant dose was associated with a 41% reduction in the percentage of days with genital lesions vs. placebo (4.5% vs. 7.9%; P < .05). According to new 12-month data, the same regimen was associated with a 49% reduction in the median genital lesion rate (P = .01), a 63% reduction in the median number of recurrences (P = .01), a 25% reduction in the median duration of recurrences (P = .02), and a 42% reduction in the rate of viral shedding (P = .02) compared with placebo.
“We demonstrated significant efficacy at our expected phase 3 primary endpoint with our phase 3 dose,” Clark said.
There were no changes in the safety profile of GEN-003 established during other studies, according to the press release. Genocea previously reported that the number of discontinuations due to adverse events in the phase 2b trial was low and similar across the dose groups and placebo. Moreover, there was no grade 4 reactogenicity or other related serious adverse events.
“With these positive data now in hand, we continue to advance toward starting our phase 3 program later this year,” Clark said. “We expect this will include both an antiviral combination study looking at the potential benefits of GEN-003 and daily Valtrex [(valacyclovir; GlaxoSmithKline)] together over daily Valtrex alone, and trials testing GEN-003 vs. placebo.”
He added that Genocea recently launched a 12-month extension of the phase 2b trial to explore the effect of a single maintenance dose at 12 months after last dose on the safety and efficacy of GEN-003.
“These data and the continued progress of GEN-003 show the potential of this immunotherapy to change the treatment paradigm for patients with genital herpes infections,” Jonathan Temte, MD, PhD, former chair of the CDC’s Advisory Committee on Immunization Practices (ACIP), said in the release. “The benefits of using a periodic immunization to achieve fewer and shorter genital herpes outbreaks without the compliance challenges of a daily pill burden would represent an extremely important alternative for patients with genital herpes. I believe the potential individual and societal benefits of a treatment such as GEN-003 to address the uncontrolled growth in genital herpes infections resonates with the goals of bodies such as the ACIP.” – by Stephanie Viguers
Reference:
Genocea Biosciences. Genocea Reports Positive Top-Line 12-Month Phase 2b Data for GEN-003 in Genital Herpes. http://ir.genocea.com/releasedetail.cfm?ReleaseID=1034082. Accessed July 26, 2017.
Disclosures: Clark and Hetherington are employees of Genocea Biosciences. Infectious Disease News was unable to confirm Temte’s relevant financial disclosures at the time of publication.