Five HIV patients are virus-free seven months after taking a new vaccine, a staggering report claims.
The treatment, developed by researchers in Spain, allowed the patients to stop taking regular antiretroviral (ARV) drugs – the current method of suppressing HIV.
Scientists have yet to test the results in a large-scale clinical trial, but they say the vaccine may be a ‘functional cure’.
It is the first step towards success in a field that has failed to find a vaccine in the last 30 years.
‘It’s the proof of concept that through therapeutic vaccination we can really re-educate our T cells to control the virus,’ says Dr Beatriz Mothe, from the IrsiCaixa AIDS Research Institute in Barcelona, Spain.
‘This is the first time that we see this is possible in humans.’
The search for an AIDS vaccine has generated massive investments and intensive efforts but, so far, not one vaccine has come to market.
After efforts and investments attempted and failed to bring a vaccine mainstream that would prevent HIV infection, researchers decided to test therapeutic vaccines.
They aim to help infected people keep the virus at bay for months or even years without ARV drugs.
Dr Mothe and her colleagues used an HIV vaccine made by Professor Tomáš Hanke from the University of Oxford in the UK.
The study included 13 participants who had taken ARVs for a little over three years on average – all within six months of being infected.
The researchers theorized that although the drugs kept down HIV levels, it limited the virus’s ability to integrate into their chromosomes, leaving them with relatively small ‘reservoirs’ of infected cells.
This should make it easier to contain the virus if the drugs are stopped, especially with the help of a vaccine, they said.
Scientists injected the participants with a series of three shots of the vaccine and they stopped taking ARVs.
After four weeks, eight of the patients saw the virus rebound. But the other five patients have gone six to 28 weeks without having to restart the treatment.
The virus became temporarily undetectable, but it has never gone above 2,000 copies per milliliter, which is the criterion to restart treatment.
Of the more than 50 therapeutic vaccine trials so far, this is the first one that has bolstered the immune system in a ‘meaningful’ way, according to Dr Steven Deeks, an HIV/AIDS clinician and researcher at the University of California, San Francisco.
He is ‘cautiously optimistic’ that the data will inspire others to study the approach.
Immunologist Dr Daniel Douek, of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, is far more skeptical.
‘The results are encouraging, but it is difficult to gauge what the effect of the procedure actually was because of the uncontrolled nature of the study and the fact that the people who remain off [ARVs] are, nevertheless, viremic,’ Dr Douek said.
But Dr Mothe said that previous ‘treatment interruption studies’ – in people who started ARVs soon after becoming infected – have found that only 10 percent of their infections under control for longer than four weeks.
In the Barcelona study, the rate was 38 percent.
HIV notoriously dodges immune attacks – and preventive vaccination – by mutating.
The researchers believe the trial’s partial success may be because the vaccine contains HIV genes that code for ‘highly conserved’ internal structures and enzymes that cannot change much without harming the virus.
Dr Deeks said: ‘Should the current trends persist, it is hard to argue that the vaccine strategy did not do something, but controlled studies are needed.’