Efficacy and Tolerability of an Antiretroviral Bi-Therapy in HIV Infected Patients With Multidrug Resistance

In patients with HIV multidrug resistance, maintaining a failing full-dose HAART regimen usually results in significant drug toxicity and in continued accumulation of resistance mutations that can preclude future therapeutic options. In contrast, treatment interruption provokes the reemergence of wild-type virus with full replicative and pathogenic capacity. The researchers investigated whether a calibrated reduction in drug pressure could stabilize the evolution and the pathogenic potential of resistant virus.

A prospective pilot study was conducted in patients receiving protease inhibitor-based HAART with a resistance genotype predicting less than two active drugs according to the 2002 ANRS algorithm, CD4 counts over or equal to 100/mm3 and plasma HIV RNA below or equal to 5 log/ml. The treatment was low-dose IDV/RTV (200/100 BID) and 3TC 150mg BID. IDV doses were adjusted at week 4 to ensure a Cmin of 250+/-100ng/ml, which, based on a panel of multi-PI resistant viruses, was calculated to yield an inhibitory quotient (Cmin/IC50) of 0.50. Primary end-points were over 25% decrease in CD4 counts (immunological failure-IF), or over 0.7 log increase in plasma HIV RNA (virological failure-VF) at two consecutive monthly visits during the 24-week study. Inclusions were to stop when the total number of failures (VF+IF) reached 7