A new study suggests that HIV patients with a higher level of a particular biomarker may respond more favourably to an experimental immune activating vaccine
Researchers at St George’s, University of London and Norwegian vaccine company Bionor believe the findings might lead to a customised vaccine for certain patients, which might permit them to come off antiretroviral drugs used to treat HIV.
The research found that the therapeutic vaccine, Vacc-4x, reduced amounts of the virus circulating in the body by more than half in patients with higher levels of the particular biomarker, compared to those with lower levels. The vaccine works by generating an immune response to conserved domains in the HIV virus. These conserved domains are genetic regions of the virus that are common to all strains of HIV, even if the virus mutates. These new results were announced on July 18th at the AIDS 2014 Conference in Melbourne, Australia.
Persistent immune responses against this conserved part of the virus (the HIV p24 protein) have been shown to delay HIV disease progression. Vacc-4x is made of modified synthetic peptides targeting these conserved regions of the HIV p24.
In phase II, 134 HIV-infected people from Europe and the US participated in a randomized, placebo-controlled study, where 93 randomly selected people where to receive Vacc-4x and 43 randomly selected people received a placebo injection. The patients were injected with either placebo or Vacc-4x in 28 weeks, followed up by 24 weeks without any injection. Eight one people successfully completed the study (week 52); 25 from the placebo group and 56 from the Vacc-4x group. The placebo group had a viral load set point of 61,900 HIV-RNA/copies/ml (median), compared to the Vacc-4x group that had a viral load set point of 22,300 HIV-RNA/copies/ml (median). This difference represents a reduction of 64% and is statistically significant (p=0.04).
Bionor Pharma is in the process of conducting two further clinical studies with the Vacc-4x, which can lead towards phase III.
Professor Angus Dalgleish, of St George’s, University of London, said: “In spite of very effective drugs against HIV these need to be taken daily and have significant side-effects. The ability to replace this daily medication with a vaccine that allows several months of being off medication, not to mention the enormous financial gains that would be delivered to health services, is a step closer with these preliminary results.”