Data from current and upcoming studies investigating a preventive HIV vaccine were presented at AIDS 2016. The updates included information on advances in the development of novel vaccines, and in the development of antibody mediated prevention.
Results from the HVTN 100 study, conducted by the HIV Vaccine Trials Network in partnership with South African research sites, were presented at the meeting. After finding that the original regimen reduced HIV infection rates among participants in Thailand by 31% over 3.5 years, the study tested immune responses of South African volunteers to a modified RV144 regimen.
“HVTN 100 used the same vaccines that RV144 tested, but made them specific to the Clade C subtype of HIV, which is widespread in southern Africa,” said HVTN 100 Protocol Chair Linda-Gail Bekker, MBChB, PhD, deputy director of the Desmond Tutu HIV Centre in Cape Town and International AIDS Society President-Elect, in a press release. “We also changed the adjuvant used with one of the vaccines, with the goal of eliciting a more powerful immune response, and added a booster injection to prolong the period of protection.”
The interim results from the study led to a phase III efficacy trial on the modified RV144 regimen. The study proceeded to the phase III trial due to the proportion of HVTN 100 participants who responded well to the vaccine.
The upcoming study, HVTN 702, will begin enrolling 5400 HIV-negative participants at 15 research sites across South Africa by the end of 2016. All participants will receive 5 injections over the course of 1 year, and will be followed for an additional 2 years of follow-up to evaluate the efficacy of the vaccine. Researchers will also evaluate findings from HVTN 100 to confirm that the RV144 regimen is safe.
“It is gratifying to see vaccines that were designed and manufactured specifically for South Africa meet and even exceed the criteria established to advance them into the large efficacy trial,” said lead investigator of the HTVN study Larry Corey, MD, in a press release. “HVTN 702 is a pivotal study that could lead to a licensed HIV vaccine in South Africa – the first preventive HIV vaccine worldwide.”
Two additional trials, called the AMP Studies, will evaluate whether a bNAb called VRCO1 is effective in preventing HIV infection. They will also determine the safety and tolerability of the VRCO1 infusion in order to evaluate what concentration of bNAn is required for HIV prevention.
Future research will also explore the design and development of antigens or immunogens that might stimulate the immune system of HIV-negative individuals to produce bNAbs. Another vaccine approach currently in development includes the exploration of “improved vectors,” which are capable of delivering HIV genes that will trigger protection against HIV.
The next vaccine regimen that will be tested in a multi-site efficacy trial will include a “mosaic” immunogen, which carries fragments of HIV from different variants of the virus and could be used globally, regardless of HIV variants in different regions.
New vigour in HIV vaccine research evident at AIDS 2016. Presented at: 21st International AIDS Conference 2016; July 18-22, 2016; Durban, South Africa.