What impact do you anticipate the recent halting of Merck's large-scale International HIV Vaccine trial to have on other HIV vaccine clinical trials?
I think the major impact will be that for more advanced trials — the Merck trial was Phase IIb and enrolled a substantial number of people — we will be much more attentive to the periodic examination of data. When the Merck trials' Drug and Safety Monitoring Board first looked at the trial data, to our surprise it showed futility in the major endpoints, namely acquisition of infection and level of viral set point. There was also a suggestion that vaccinated people with background immunity to the adenovirus vector had a greater susceptibility to acquiring HIV infection. Based on the latter observation it will be necessary for us to put a pause on vaccine studies that involve an adenovirus vector performed in populations who may be at risk for HIV infection. In addition, in the future we will look very carefully at the results on a more frequent basis. It is a sobering revelation that what we thought was a promising product actually failed the first time. It is not going to diminish our enthusiasm and support for vaccine research because we still need to keep the pipeline robust. But when we get into more advanced clinical trials in the future, it will be done with an added degree of caution.
