Experimental HIV Vaccine Goes to Human Trial

An experimental Johnson & Johnson vaccine completely prevented HIV infection in half of monkeys that got the shot and then were exposed to high doses of an aggressive virus, results that spurred the company to test the vaccine in people, academic and company researchers said on Thursday.

The international trial is underway in 400 healthy volunteers in the United States, East Africa, South Africa and Thailand. It is the first time since Merck's failed 2007 trial that a major pharmaceutical company has sponsored clinical development of an HIV vaccine, said Dr. Dan Barouch, a vaccine researcher at Beth Israel Deaconess Medical Centre and the Ragon Institute of Massachusetts General Hosptial, MIT and Harvard.

Some 35 million people are infected with HIV, the virus that causes AIDS. Since it began spreading 30 years ago, AIDS has killed 40 million people worldwide.

Despite progress in treatments, experts believe a vaccine is the best hope for eradicating the disease.

In a pair of studies, published online in the journal Science, Barouch and colleagues at J&J and elsewhere tested a two-step vaccine, which involves priming the immune system using a weakened version of the cold virus to sneak HIV genes into the body. The second, boost phase involves injecting individuals with a purified HIV surface protein designed to provoke a strong immune response.

The company is using the same prime-boost strategy in its Ebola vaccine, now in early-stage human trials, Dr. Paul Stoffels, J&J's chief scientific officer and worldwide chairman, pharmaceuticals, told Reuters.

Stoffels said the HIV vaccine trial in monkeys was designed to test the limits of the vaccine, exposing the animals to high levels of an aggressive virus that attacks non-human primates known as simian immunodeficiency virus, a close cousin to HIV.

The virus was potent enough to infect 100 percent of unvaccinated animals after six exposures. Even so, half of the animals who got the vaccine were completely protected.

Stoffels said the infection rate per exposure in the trial is about 100 times greater than what is typically seen in humans. J&J expects the vaccine to prove even more effective in people, but even if the vaccine only protects half of those people who get it, "it will still have an enormous public health impact," Stoffels said.

If all goes well with the early-stage trial, Stoffels expects a larger, phase 2b study would start in the next 18 to 24 months.

© Thomson Reuters 2015