CCR5 antagonists in the treatment of treatment-experienced patients infected with CCR5 tropic HIV-1

CCR5 antagonists are a newly developed class of antiretroviral drugs which inhibit viral entry into the host cell by binding to the predominant HIV coreceptor. Data on the use of these new drugs in treatment-experienced HIV patients are emerging. Clinical trials on maraviroc and vicriviroc in pretreated patients recruited more than 1300 individuals. Interim results of these studies indicate that pretreated patients infected with CCR5-tropic viruses benefit from their use in optimized combination regimens. Maraviroc reduces the HIV-1 viral load in patients with previous triple-class failure by 1.96 log(10) copies/ml versus 0.99 log(10) copies/ml in placebo; vicriviroc shows potency by dose depending viral decrease of 1.51 - 1.68 log(10) copies/ml compared to 0.29 log(10) in placebo. As expected, CCR5 antagonists do not reduce viral load in patients harbouring CXCR4-tropic or dual/mixed tropic viruses. Nevertheless, since a considerable percentage of late-stage HIV patients still bear CCR5-tropic viruses, the use of CCR5 antagonists appears promising in properly selected treatment-experienced patients.