The trial was designed to test for safety and researchers did not expect to see a significant response.
The results of a small therapeutic vaccine trial conducted in South Africa were largely overlooked at this year’s International Aids Conference in the wake of the microbicides breakthrough.
But the research could have great benefit for South Africa. Unlike preventative vaccines, which aim to immunise uninfected patients against HIV, therapeutic vaccines would boost the immune response of patients who already have the virus.
This type of vaccine could keep patients healthy for longer and delay the point at which people need to begin antiretroviral therapy (ART), which, in turn, would ease the strain on the health system. The vaccine was tested on 60 volunteers at the Wits clinic in Soweto.
The patients, who began the trial with CD4 counts above 500, were not yet eligible for ART. The trial was designed to test for safety and researchers did not expect to see a significant response. But when the two-year study ended, the amount of HIV circulating in the patients’ blood had dropped and their CD4 counts had increased.
The effect was slight but significant enough to warrant another trial. “We never expected to see such a good result for so long,” said principal researcher Eftyhia Vardas of the Perinatal HIV Research Unit at Wits University. It was the first time a therapeutic vaccine was tested in South Africa and the first time such a vaccine was used on patients not already on ART.
Kalevi Reijonen, chief executive of FIT Biotech, which funded the trial, said that if all goes to plan a vaccine could be available by 2016. “This study clearly gives us hope and proves it is possible to develop a therapeutic vaccine,” said Reijonen. But vaccine experts warned that it was too early to make assumptions about the vaccine’s effectiveness.
“I would be wary of overinterpreting a small trial designed for safety and not for efficacy,” said Seth Berkley, president of the International Aids Vaccine Initiative. Mitchell Warren, executive director of the Aids Vaccine Advocacy Coalition, said that while the results are encouraging, a larger and longer trial is needed to confirm the results.
Therapeutic vaccines do not have the same support that preventative vaccines or microbicides do. Some $38.6-million was invested in therapeutic vaccines last year. In contrast, $868-million went to research into a preventative HIV vaccine and $236-million to microbicide research.