Pharma

Immunotherapy for STI treatment: Agenus CEO on its genital herpes vaccine

Many companies are contending to hit the market first in the race for a genital herpes […]

Many companies are contending to hit the market first in the race for a genital herpes vaccine. The thread that ties them together? Immunotherapy – the wunderdrug for cancer therapy that’s now showing promise for infectious disease.

But it hasn’t always been so, said Agenus CEO Garo Armen, whose immunotherapy approach in both cancer and in infectious disease like herpes had been “pooh-poohed” for years.

“We’ve been doing this for 20 years – and were really being ridiculed for a while,” Armen said. “But then, all of a sudden, everyone loves immunotherapy, in the context of cancers in particular.”

The Massachusetts company has been slowly developing immunotherapy treatments for malaria, a number of cancers and herpes – keeping staunchly at it even when it fell out of favor in the ’90s.

“Immunotherapy has been snubbed for many, many years – even though 3,000 years ago, the ancient practice of medicine was basically betting on the immune therapy to do things,” Armen said. “For the last 40 to 50 years, people have sort of pooh-poohed the fact that the immune system can really do things.”

All this turned on its head, Armen said, about three years ago when immunotherapy started receiving more wide acceptance – particularly in treating cancer. Bristol-Myers Squibb developed the monoclonal antibody Yervoy, and Merck’s PD-1 inhibitor Keytruda – moves Agenus is associating itself with in that rising-tide-raises-all-ships kind of way.

“We’re confident that, like cancer, immunotherapy is going to become the standard of care to treat infectious diseases like herpes,” Armen said.

Agenus’ (Nasdaq: AGEN) HerpV vaccine uses a heat shock protein, called gp96, as well as a QS-21 adjuvant that helps activate the immune system against the herpes virus. Early stage clinical results, Armen said, found Agenus’ QS-21 adjuvant was associated with an increase in cellular immune responses – what he says was the first instance of a vaccine candidate eliciting both T cell and helper cell immunity in human subjects.

The company last released data in June, which said that in its randomized, Phase 2, double-blind study most patients showed an immune response to HSV antigens after being inoculated with a series of herpes vaccines and a booster at six months. It said:

More than half of those vaccinated developed a robust anti-HSV cytotoxic T-cell immune response, and in those patients there was a statistically significant 75% reduction in viral load (P<0.001; CI: 46.2 – 88.6%). This level of reduction in viral load has the potential to result in reduced incidence and severity of herpetic outbreaks and a reduction in viral transmission

Adversaries, like San Diego’s Vical, Australia-based Admedus and the Boston-area Genocea, have a similar approach – vaccines and boosters to enhance immune system efficacy. And like its fellow developers of the genital herpes vaccine, Agenus is hoping first to create a treatment for already-infected individuals, then expand into the prophylactic vaccine space.

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