CCR5 Blockers and HIV Suppression

CCR5 Blockers and HIV Suppression

Studies of how unique genetic characteristics influence disease progression has led to some clinical advances. It was the discovery that there is a secondary receptor on the surface of CD4 cells (the targets for HIV infection) and that some remain healthy with delayed progression if they have a specific genetic alteration in this gene that led to the development of new class of drugs to combat HIV infection. At this meeting there was data presented on two new drugs being developed to block one of these co-receptors, referred to as CCR5. In fact, CCR5 blockers are being simultaneously developed by three different companies. The data presented on the drug called maraviroc and SCH 417,690, both demonstrating excellent HIV suppression in blood with short term therapy and to be very well tolerated. Larger studies are underway with these drugs, as well as one being developed by a third company, to define the utility of these promising agents in those who are starting antiretroviral therapy for the first time and who are drug experienced with limited options. These are very promising agents for the future and offer people living with HIV great hope in their individual battles against HIV infection.

Limitations of Current Therapy

While these studies show great promise for the future, other studies demonstrated limitations of current therapy, including one showing how didanosine (Videx™ and tenofovir DF (Viread™), both agents that are very effective as part of combination therapy should not be used together as part of a first line regimen. In this case, the study showed what these drugs combined with efavirenz (Sustiva™) had led to an unacceptable failure rate. This does not necessarily mean that those doing well on this combination should necessarily stop, just that it should be avoided when possible as up front therapy. Further studies reviewed available literature on a potential toxicity associated with tenofovir DF, namely kidney problems. There were several studies that looked at this carefully and while many did show some mild decreases in kidney function in those on this drug, the change was for the most part quite modest and remains of unknown clinical significance.