Short communication: activity of etravirine on different HIV type 1 subtypes: in vitro susceptibility in treatment-naive patients and week 48 pooled DUET study data.

Etravirine (ETR) has previously shown potent in vitro activity against different primary HIV-1 isolates and demonstrated durable efficacy in treatment-experienced, HIV-1-infected patients in the Phase III DUET studies. The antiviral activity and efficacy of ETR against HIV-1 subtypes B and non-B were further investigated. The effect of HIV-1 subtype on ETR fold change in EC(50) value (FC) was analyzed in HIV-1 recombinant clinical isolates from 673 treatment-naive patients enrolled in other Tibotec studies. Subgroup analyses from the DUET studies of the effect of HIV-1 subtype on the proportion of patients with viral load (VL) <50 HIV-1 RNA copies/ml were also conducted using pooled week 48 data. Genotype/subtype and phenotype determinations were performed using the vircoTYPE HIV-1 and Antivirogram assays, respectively. In vitro results from treatment-naive patients indicated comparable median ETR FC in virus isolates from patients infected with subtype B or non-B (1.1 vs. 1.2, respectively). HIV-1 subtype data were available for 594 and 595 patients in the ETR and placebo groups of the DUET studies, respectively; 94% of patients harbored subtype B. Baseline characteristics were similar across the different subtypes, with the exception of a higher number of sensitive NRTIs used in patients with subtype non-B. At week 48, virological responses in the ETR group were higher in patients with subtype non-B versus B (73% vs. 60%, respectively). ETR was equally effective in suppressing viral replication in patients infected with HIV-1 subtype B or various HIV-1 non-B subtypes.