WASHINGTON – The near 40-year quest for an AIDS vaccine received a hopefulboost on Saturday when scientists announced that a trial drug triggered animmune response in humans and shielded monkeys from infection.
Shown to be safe in humans, the candidate vaccine has now advanced to thenext phase of the pre-approval trial process, and will be tested in 2,600women in southern Africa to see whether it prevents HIV infection.
While the results so far have been encouraging, the research team andoutside experts warn there are no guarantees it will actually work in thenext trial phase dubbed HVTN705 or “Imbokodo” — the isiZulu word for “rock”.
“Although these data are promising, we need to remain cautious,” DanBarouch, lead researcher and a Professor at Harvard Medical School, said.Just because it protected two-thirds of monkeys in a lab trial does notmean the drug will protect humans,” and thus we need to await the resultsof the… study before we know whether or not this vaccine will protecthumans against HIV infection,” he said.
The results of the Imbokodo trial are expected in 2021/22.
“This is only the fifth HIV vaccine concept that will be tested forefficacy in humans in the 35-plus year history of the global HIV epidemic,”added Professor Barouch.
Only one so far, RV144, yielded some protection. RV144 was reported in 2009to reduce the risk of HIV infection among 16,000 Thai volunteers by 31.2% —deemed insufficient for the drug to be pursued.
For the latest study, published in *The Lancet *medical journal, ProfessorBarouch and a team tested the candidate drug on 393 HIV-free adults aged 18to 50 in east Africa, South Africa, Thailand, and the U.S.
The participants were randomly given one of seven vaccine combinations or aplacebo “dummy” alternative. They received four shots each over 48 weeks.
‘Mosaic’ combinations
The study used so-called “mosaic” vaccine combinations.
These combine pieces of different HIV virus types to elicit an immuneresponse — when the body attacks intruder germs — against virus strainsfrom different regions of the world.
The vaccine “induced robust (high levels of) immune responses in humans,”said Professor Barouch.
The tests also showed the vaccine was safe. Five participants reportedside-effects such as stomach pain and diarrhoea, dizziness, or back pain.
In a separate study, the same vaccine offered complete protection frominfection in two-thirds of 72 trial monkeys each given six injections withan HIV-like virus.
“I cannot emphasise how badly we need to have a vaccine… to get rid ofHIV in the next generation altogether,” said Francois Venter of theUniversity of the Witwatersrand Reproductive Health and HIV Institute inSouth Africa.
“We have been here before, with promising candidate vaccineslink>thathaven’t panned out,” he said.
“This one is novel in many ways so it is exciting, but we have a long wayto go.”