Genocea's phase 2 genital herpes data help 'de-risk' a larger trial set to start this year: analyst

Genocea's genital herpes therapeutic vaccine GEN-003 reduced the median genital lesion rate by 49% after 12 months.

Genocea shares already jumped after the company released 12-month topline data from a phase 2b study for its genital herpes therapeutic vaccine, but one analyst believes things may get a whole lot better at the biotech.

In what “may be the most important data in Genocea’s history,” the new trial showed GEN-003 can sustain a significant reduction in genital lesions after 12 months, CEO Chip Clark said during a conference call Monday morning.

Investigators found that, when given together with a smaller dose of 50 µg of adjuvant, the 60 µg-per-antigen vaccine managed to reduce participants' days with genital lesions by 49% compared to placebo. That’s consistent with the 52% median (or 41% mean) improvement observed after six months of vaccination.

In previous trials, the shot was able to improve viral shedding rate, but since the lesion rate is clinically more beneficial for patients, the company has set it as the primary endpoint for an upcoming phase 3 study slated to begin this year.

RELATED: Genocea armed with positive phase 2b data on potential blockbuster herpes vax

This means that GEN-003 has already shown promise against the phase 3 endpoint, Cowen analyst Phil Nadeau wrote in a note to investors.

“The fact that GEN-003 was able to persuasively hit this endpoint in phase 2 provides strong proof-of-concept, and helps to de-risk the phase 3 program,” Nadeau said. “Our consultants have been impressed by GEN-003's profile and anticipate that patients will be willing to use it.”

Nadeau estimates GEN-003’s market size at over $2 billion if priced at $300 per course. 

The lower-dose regimen also performed well in several secondary endpoints in the latest study, except for viral shedding rate, but management said the numbers were probably skewed by lower numbers of subjects monitored and a shorter testing window.

The 131 subjects that participated in this phase 2b will be given a single maintenance dose at month 12 for further evaluation of GEN-003’s efficacy and durability. In a previous phase 2 trial, the shot was able to significantly reduce lesion rate after 24 months.

Clark said that the company is currently in talks with potential partners, and since Genocea is itself based in the U.S., it might be depending on a partner to maximize the shot’s potential in the global market outside. However, he didn’t rule out the possibility of a domestic partnership.