Thursday, September 19, 2013

I called an important Summit that took place at Bethesda North Marriott. Purpose was to discuss the advisability of using Adenovirus vectors for HIv vaccines given the failures of Ad5 vectors in 3 vaccine trials, but more importantly the fact that there were “trends” in each study that showed an enhancing effect on acquisition of infection in the vaccines who received the Ad5 vector. Meta-analysis of the 3 studies showed a significant (<0.01) 32% enhancement of infection. Big question is that there are ongoing plans to use other vectors (Ad26, among others) in future HIV vaccine trials as well as in non-HIV vaccine trials (malaria, TB, etc.) in populations that might be at risk for HIV. Seems to me that any vaccine that activates cells that might migrate to the mucosal surface can have an enhancing effect that is seen if the vaccine is not efficacious. If the vaccine is efficacious, then the enhancing effect is masked as might have been the case with the 31% efficacy of the RV144 trial. Important issue is to try to get the efficacious vaccine and not do a trial on an Ad vector unless it shows an immune response that would be better than any other vaccines that we have tried.