Virological response to short-course maraviroc monotherapy does not predict viral tropism in HIV-1-infected treatment-naive patients

Abstract
Objectives
We aimed to evaluate whether virological response to a short course of maraviroc monotherapy could predict HIV-1 tropism.

Methods
A clinical trial was performed in HIV-1 treatment-naive patients infected with R5- or non-R5-tropic virus determined using the Trofile® assay, with >1000 HIV-1 RNA copies/mL. Maraviroc was administered for 10 days. Viral load was measured at baseline and days 4, 7, 10 and 28. The main outcome measurement was the decline in HIV-1 RNA at day 10. The trial was registered in the ClinicalTrials.gov database (NCT01060618; TROPISMVC).

Results
Forty patients [30 R5 and 10 dual/mixed (D/M)] were recruited. There was a significant decrease in HIV-1 RNA after 10 days of maraviroc treatment in patients with R5-tropic virus (median 1.52 log10 RNA copies/mL; 95% CI 1.23–1.63; P < 0.0001), but also in patients with D/M-tropic virus (median 1.62 log10 RNA copies/mL; 95% CI 0.33–1.88; P = 0.00024). The difference in the HIV-1 RNA decrease (−0.16 log10 RNA copies/mL; 95% CI −0.53 to 0.22) was not significant (P = 0.410). A decrease >0.5 log10 RNA copies/mL was found in 96.3% of patients with R5-tropic virus and in 70% of patients with D/M-tropic virus (P = 0.052). The differences were not significant when a decline of 1 log10 RNA copies/mL was considered (92.6% versus 70%; P = 0.11).

Conclusions
Treatment-naive patients infected with R5- or D/M-tropic virus have similar virological responses to a short course of maraviroc monotherapy. This clinical test thus cannot be used as a surrogate marker of viral tropism in this population.