At the AIDS 2016 conference, study authors presented plans for the HVTN 702 study, a critical trial that could lead to the first licensed preventive HIV vaccine in the world.
The HVTN 100 study evaluated immune responses of South African study participants to a modified version of the RV144 regimen, the only HIV vaccine regimen that has demonstrated efficacy so far. The original RV144 vaccine showed a 31% reduction in HIV infection rate among Thailand study participants over 3.5 years. For this study, however, the RV144 vaccine was made specific to the Clade C subtype of HIV, the adjuvant was changed for one of the vaccines, and a booster injection was added.
The favorable interim data regarding the percentage of HVTN 100 vaccine recipients who exhibited a range of immune responses and the strength of those responses paved the way for a Phase 3 efficacy trial to commence evaluating the modified RV144 regimen. The placebo-controlled HVTN 702 study will enroll 5,400 HIV-negative women and men across 15 research sites before the end of 2016.
Study participants will receive five injections over 1 year and will be followed up for 2 years to establish whether the vaccine elicits a sustained protective benefit. The study will also look to confirm previous findings from HVTN 100 regarding the safety of the modified RV144 regimen.
Researchers also presented the launch of the AMP Studies, the first large-scale human trials to evaluate whether a broadly neutralizing antibody (bNAb) called VRC01 given as an infusion, can prevent against acquiring HIV. The two studies involved are HVTN 704/HPTN 085 (n=2,700) which launched in March, and HVTN 703-HPTN 081 (n=1,500) which launched in June. The AMP Studies will investigate the safety and tolerability of the VRC01 infusion and determine what concentration is needed for effective prevention. In addition, scientists are studying the development of antigens or immunogens that might stimulate the immune system of HIV-negative people to produce bNAbs.
A future multi-site efficacy trial is likely to test a vaccine regimen that includes a “mosaic” immunogen, which carries HIV fragments from different variants of the virus. This complex immunogen is thought be globally relevant despite the predominant variants in different areas. Another possible vaccine approach involves improved vectors that can deliver HIV genes to trigger protection against HIV or those that may be able to deliver bNAb genes directly.
For more information visit AIDS2016.org.