Week-12 Response to Therapy as a Predictor of Week 24, 48, and 96 Outcome in Patients Receiving the HIV Fusion Inhibitor Enfuvirtide in the T-20 versus Optimized Regimen Only (TORO) Trials

Background. Early virological response to antiretroviral therapy is predictive of long-term treatment outcome in therapy-naive patients. In treatment-experienced patients, such correlations are less well defined, because initial responses may be less pronounced and transient because of accumulated cross-resistance to prior therapies. Our objectives were to explore how the virological and immunological status of treatment-experienced patients at an early time point (week 12) during enfuvirtide-based therapy predicted their responses at weeks 24, 48, and 96 in the T-20 versus Optimized Regimen Only (TORO) trials. Methods. Post hoc, modified, on-treatment and intent-to-treat analyses were performed to determine whether the relationship between virological and immunological outcomes at weeks 24, 48, and 96 were predicted by the patients' week-12 responses to therapy. Results. Using a modified on-treatment analysis for patients who, by week 12, achieved a decrease in their HIV-1 RNA load of ⩾1 log10 copies/mL, 39.2% (95% CI, 33.6%–44.8%) and 59.5% (95% CI, 53.8%–65.1%) achieved a viral load of