Experimental AIDS vaccine shows promise in monkey trial
Johnson & Johnson’s experimental AIDS vaccine protected half the monkeys who received it in a study, boosting confidence in the possibility for a shot that would stop the world’s deadliest infectious disease in humans.
The vaccine protected six out of 12 animals who received it from becoming infected with the monkey version of HIV, according to findings published Thursday in the journal Science. J& J has started the first human trials of an AIDS vaccine since 2009 among 400 volunteers in the US, Thailand, South Africa, Rwanda and Uganda, and expects results next year.
Efforts to develop a preventive AIDS vaccine have repeatedly foundered against a virus that has proved a wily foe. Only four vaccines have made it as far as human studies, and only one showed any hint of working. Drug companies have avoided HIV vaccine trials ever since a shot backed by Merck & Co. appeared to increase the risk that participants would contract the virus.
“We think that there is a very good chance that we’ll show efficacy,” Paul Stoffels, J& J’s chief scientific officer, said by phone. “Of course, all to be proven, but the stars are aligned here that we will see something in humans.”
The current trial tests whether the vaccine is safe and generates an immune response. If results are positive, J& J will progress to a large study aimed at proving the vaccine can protect people, which may have results by 2020, Stoffels said.
The vaccine consists of two parts: a cold-causing virus that smuggles three HIV proteins into the body, priming the immune system to generate antibodies. That’s followed by a booster consisting of a purified HIV protein that enhances the response.
Scientists from the Beth Israel Deaconess Medical Center in Boston vaccinated 12 monkeys with the so-called prime-boost vaccine, a further 12 with just the prime vaccine, and eight with sham inoculations. They then gave the monkeys six doses of monkey-HIV that were each 100 times more infectious than what humans are typically exposed to.
Among the animals that got the prime-boost vaccine, six remained HIV-free, as did two that only received the prime. The monkeys that received a placebo were all infected. To prove the point, the researchers took blood from the protected monkeys and gave it to new monkeys to see whether they would become infected — they didn’t.
“There’s more reason to be optimistic now than ever before, but we still have a long ways to go,” said Dan Barouch, a professor of medicine at Harvard Medical School who led the study. “Over the course of the HIV epidemic there have only been four concepts that have been tested in humans. We need more shots on goal.”
More than 35 million people are living with HIV and more than 2 million people were newly infected in 2013, according to the Joint United Nations Programme on HIV/AIDS, or UNAIDS. While the number of AIDS-related deaths has been dropping for years, finding a vaccine remains key to ending the epidemic.
“Curing HIV is not an option for the moment because of the complexity of the biology,” Stoffels said. “We think that the only solution is HIV vaccines to prevent people getting infected.”