Genocea Climbs on Follow-Up Data for Herpes Vaccine

Xconomy Boston — 

It hasn’t all been smooth sailing for Genocea Biosciences as it tries to prove the worth of a new, quick-hit vaccine technology. The company currently trades well under its 2014 IPO price, and hasn’t been able to break out like some other biotechs in the recent boom. But the Cambridge, MA-based company is getting some love from investors this morning, thanks to some new data on a vaccine it’s been developing for genital herpes.

Genocea (NASDAQ: GNCA) said this morning that the vaccine, known as GEN-003, succeeded in its latest test. This was a follow-up of 310 patients who’d been given GEN-003 or a placebo in Genocea’s Phase 2 trial, and the company has been tracking these folks to see how they’ve fared six months after a three-shot treatment regimen—the most substantial insight Genocea has offered so far as to the staying power of the vaccine in patients.

Specifically, Genocea wanted to see if GEN-003 continued to reduce what’s known as “viral shedding”—when the the patient is releasing the virus and so is contagious—and to what extent that translated to fewer outbreaks of blisters and sores.

The primary goal of this test was to reduce patients’ viral shedding compared to their baseline levels, and Genocea said it’s succeeded here, with four out of the six doses that were tested achieving statistically significant reductions. The “best performing dose”—60 micrograms of GEN-003 combined with 75 ug of an accompanying adjuvant—led to a 58 percent decrease in viral shedding at the six month mark.

Genocea said that five of the six doses of its vaccine also led to “sustained and statistically significant reductions” in blisters and sores compared to baseline. These reductions ranged from 43 to 69 percent after six months, though it’s unclear which doses achieved these rates. GEN-003 led to a 48 percent reduction in viral shedding and a 52 percent reduction in lesions in its previous, Phase 1/2 trial. In regulatory filings, Genocea has said that its consultants believe repeating similar results in a late-stage would make GEN-003 a “commercially viable” product.

Investors cheered the latest results, sending shares up more than 23 percent in pre-market trading before they settled back down to a 12 percent gain as of 10:30 a.m. ET. (Still, the $6.65 price Genocea is trading at comes in well short of its $12 a share IPO price in February 2014).

Some other notes on GEN-003, according to Genocea:

—Some 30 to 50 percent of those on GEN-003 were free of lesions six months after dosing, which Genocea said is comparable to past clinical trial results with oral antiviral drugs like valaciclovir (Valtrex), which are the standard of care for breakouts.

—Genocea analyzed how long it took for patients to have their first lesion flare-up after treatment, and found the time ranged from 152 days to over 180 days.

—No serious safety issues popped up in the study.

—Genocea will present the full data later this week at a conference in San Diego.

Genocea will track these patients for another six months to see how they do, and aims to wrap up its Phase 2 program and meet with the FDA to discuss the design of a late-stage study in late 2016.

“These data support the potential of GEN-003 to serve as a cornerstone therapy for genital herpes infections with convenient, long term viral shedding and symptom control,” CEO Chip Clark (pictured above) said in a statement. “Given the excellent results at six months, which reinforce GEN-003’s existing strong profile, upside exists from potential efficacy at twelve months.”

Genocea had announced positive results from this trial in May, observing how patients fared 28 days after their third and final shot, and saw its shares temporarily rise afterwards. But there was a caveat to the data. Genocea had said that even patients on a placebo responded—they saw a statistically significant reduction in lesions compared to baseline, meaning it was unclear what type of differentiation there was between a placebo and GEN-003.

According to Genocea chief medical officer Seth Hetherington, the company believes that a placebo effect was seen because a “high level of anticipation” for the vaccine and because of how the trial was structured—a 6 to 1 randomization between patients on GEN-003 and those on placebo. After the initial results, Genocea switched the placebo patients over GEN-003, which is why it’s not being compared to a placebo in this data readout, Hetherington said.

“In larger Phase 3 trials with more balanced randomization ratios, Genocea is confident the placebo effect will go away,” he added.

For those unfamiliar with Genocea, it was created around the work of Harvard University immunologist Darren Higgins. The company has spent years developing and fine-tuning a platform that’s supposed to make it quicker and easier to produce a vaccine by significantly cutting down the time it takes to discover antigens—the substances in vaccines that trigger a disease-fighting immune response.

Genocea is also using that platform to create vaccines that trigger responses both from B cells (the ones that produce antibodies) and T cells. All of the currently approved vaccines work in a more limited way, by teaching B cells to fight microbes.

The company is also expected to disclose the first results from a Phase 2 clinical trial of its pneumococcus vaccine, GEN-004, this quarter as well.