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Investigational HIV vaccine regimen the first to show protective benefits
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Combining two experimental HIV vaccines lowered the rate of HIV infection by 31.2% in 51 adult vaccine recipients compared with 74 patients in a placebo group, data from a phase-3 clinical trial indicated.
“This is the first HIV vaccine candidate to successfully reduce the risk of HIV infections in humans,” Lieutenant General Eric B. Schoomaker, MD, PhD, and U.S. Army Surgeon General, said in a press release. The RV144 trial was sponsored by the U.S. Army, conducted in Thailand, and involved 16,000 adult volunteers.
The researchers randomly assigned participants to receive either primary vaccine (Alvac HIV, Sanofi Aventis) with a booster vaccine (AIDSVax B/E, Global Solutions for Infectious Diseases) or placebo during a six-month period. The two vaccines were chosen based on the most common circulating HIV subtypes in that region.
After a three-year follow-up period that screened participants for HIV every six months, findings showed that using a prime-boost vaccine regimen was safe and modestly effective at preventing HIV infection. However, it did not affect the viral load of volunteers who contracted HIV during the study.
More details from the trial will be presented at the AIDS Vaccine Conference in Paris this October. The U.S. Army in collaboration with the Thai Ministry of Public Health, the National Institute of Allergy and Infectious Disease and both vaccine manufacturers are working with experts in the field to determine how these findings will affect other HIV vaccine candidates.
“These results show that development of a safe and effective preventive HIV vaccine is possible,” said Colonel Nelson L. Michael, MD, PhD, director in the division of retrovirology at the Walter Reed Army Institute of Research and director of the U.S. Military HIV Research Program. “While these results are very encouraging, we recognize that further study is required to build upon these findings.”
Officials from the Treatment Action Group said that although the study results are welcome, more study is warranted.
“These results are very welcome given the many unwelcome surprises that have assailed the HIV vaccine field over the past few years,” TAG officials wrote in a press release. “However, based on the limited amount of information that has been released, it appears that the statistical significance hangs on very few cases of HIV infection. TAG urges caution in interpreting the findings until more detailed information is available. “
When the trial was launched, TAG officials stated their concern that the lack of data on the efficacy of ALVAC alone would preclude an understanding of whether the inclusion of AIDSVAX added to, or subtracted from, any potential benefit (Science. 305;5681:180).
Now that there is an indication of possible efficacy, this issue looms large and TAG officials said this issue needs to be studied in greater detail.
The executive director of the Global HIV Vaccine Enterprise, Alan Bernstein, said the results showed a vaccine was an achievable goal.
“This is a historic day in the 26-year quest to develop an AIDS vaccine,” said Bernstein. “This trial is the first demonstration in humans that, with more research, it will be possible to develop a vaccine that is fully protective against HIV.”