The HCPLive Peer Exchange: Optimizing Outcomes in HIV Treatment features insight and opinion on the latest developments in HIV research, diagnosis, and management from leading physician specialists.
This Peer Exchange is moderated by Paul Doghramji, MD, who is a family physician at Collegeville Family Practice in Collegeville, PA, and Medical Director of health services at Ursinus College, also in Collegeville, PA.
The panelists are:
In this segment, the panelists discuss current efforts to develop a safe and effective HIV vaccine.
Dr. Frank noted that there is a lot of work going on in the field of HIV vaccine development right now, specifically mentioning the RV144 vaccine study (also known at the Phase III HIV Vaccine Trial) that was published in The New England Journal of Medicine. That trial, conducted with more than 16,000 volunteers in Thailand, was the largest HIV vaccine trial conducted in humans. According to Dr. Frank, it showed a modest reduction in HIV acquisition, using vaccines that were not thought to be very effective. From the Thai study, he said that we now know “some immunologic factors that correlated with protection from HIV acquisition,” and now the field is focused on “trying to develop vaccines that would mimic the same kind of immune responses that were seen in that study in a higher proportion of the population and to a greater magnitude.”
However, Dr. Frank said there are many reasons to be pessimistic that it’s even possible to develop an effective HIV vaccine, certainly within the next 10 years. In the meantime, he said there is another study that is attempting to duplicate the Thai study, and there is talk of doing a prevention trial using passive immunotherapy in which individuals will be given antibodies by infusion or by injection to see if that strategy will prevent HIV acquisition.
Dr. Frank said that “Obviously, that is not going to be a strategy that is going to be applied to the population at large, but it will be a very important proof of principle study to demonstrate that neutralizing antibodies can prevent the acquisition of HIV.”
As to the challenges associated with developing an effective HIV vaccine, Dr. Sax said that the fundamental problem is that the main target of HIV is the CD-4 cell, and the question for researchers is “What is it that would provide a neutralizing antibody at a level that’s protective, at the mucosa that’s protective from injection drug use or exposure to blood?” He said investigators have not been able to find a consistent neutralizing antibody or ways to generate it in people, in part because “the surface of the virus changes a lot.”