Atazanavir/r plus maraviroc or tenofovir/FTC in treatment-naive patients
Simon Collins, HIV i-Base
Maraviroc, has not been approved for first-line therapy because it failed to meet non-inferiority criteria compared to efavirenz.
The results from phase 3 studies were complicated by the dependence on early less sensitive tropism test and an unexplained difference between responses in northern compared to southern hemisphere countries. This has limited the potential to use maraviroc earlier in treatment.
In Vienna, interim 24-week results were presented from a pilot phase 2b study of boosted atazanavir plus either maraviroc (n=60) or tenofovir/FTC (n=61).  A larger phase 3 study with the same design is also ongoing. This is an international study with over 30 sites in the US, Germany and Spain, although it recruited mainly from US sites.
Baseline demographics included 85-93% male, 75% white, 20% black, median age 37 years (range 18-68) with median (range) CD4 and viral load of 350 cells/mm3 (110900) and 4.6 log copies/mL (3.45.9), respectively.
The study was not powered for treatment effect. Lower virological response (80 vs 89% <50 copies/mL) and increased side effects (ie 33% vs 23% grade 3/4 including 26% vs 13% hyperbilirubinaemia), were reported in the maraviroc vs atazanavir/r arms respectively. Virological response by baseline viral load was 80% vs 95% and 81% vs 77% for the <100,000 and >100,000 copies/mL maraviroc and tenofovir/FTC groups respectively. The PK sub-study in 15 patients important because a positive interaction supports maraviroc 150mg once-daily with some boosted PIs reported that all patients exceeded the Cavetarget of >75 ng/mL at week 2
- Portsmouth S et al. Safety and immunovirological activity of once daily maraviroc (MVC) in combination with ritonavir-boostedatazanavir (ATV/r) compared to emtricitabine 200mg/tenofovir 300mg QD (TDF/FTC) + ATV/r in treatment-naive patients infected with CCR5-tropic HIV-1 (Study A4001078): A week 24 planned interim analysis. 18th IAS Conference, 1823 July 2010, Vienna. Late breaker abstract THLBB203.