The authors of the report in AIDS for September 24 point out that simplified maintenance for HIV patients is being sought. Ritonavir-boosted lopinavir (LPV/r) monotherapy has looked promising but there are concerns about limited drug penetrance in the central nervous system and genital tract allowing HIV replication in those compartments.
To look into this issue, Dr. Pietro L. Vernazza with the Cantonal Hospital St. Gallen in Switzerland and colleagues conducted an open-label study of 60 patients with HIV who had viral loads <50 copies/mL on antiretroviral therapy. They were randomized to LPV/r 400/100 mg twice daily (monotherapy) or to continuation of triple therapy for 96 weeks, with an optional switch to monotherapy offered to all patients on continued treatment at week 48.
During the study period, six patients among those assigned or switched to monotherapy had virologic failure with two consecutive plasma HIV RNA levels greater than 400 copies/mL, and the trial was stopped.
No failures occurred in the continued-treatment group.
All the failures occurred in patients who had had CD4 nadirs below 200 cells/microliter. Five of the six failure patients who consented to a spinal tap all had elevated HIV RNA levels in CSF, and four had neurologic symptoms — headache, dizziness, visual disturbance, decreased concentration and ataxic gait.
There was no notable elevation of HIV RNA in genital secretions, the authors note.
“Maintenance of HIV therapy with LPV/r alone should not be recommended as a standard strategy; particularly not in patients with a CD4 cell count nadir less than 200/microliter,” Dr. Vernazza and colleagues conclude.
They add, “Further studies with long-term follow up and evaluation of monotherapy efficacy in CNS are needed before monotherapy generally can be considered as an option for HIV therapy.”