Predictors of virological response in HIV-infected patients to salvage antiretroviral therapy that includes nelfinavir

Different salvage strategies have been used to regain control in patients with HIV who have virological failure on combination antiretroviral therapy. We conducted a cohort study of 63 extensively antiretroviral pretreated patients who initiated nelfinavir as part of salvage therapy, to determine predictors of virological response. The maximum HIV RNA response was >0.5 log(10) copies/ml reduction in 43 patients (68%), including 21 patients (33%) who had suppression to < 500 copies/ml. Corresponding response rates at 24 weeks were 41 and 19%, respectively. Responders and non-responders could not be distinguished by mean baseline HIV RNA or CD4 cell count, duration of prior protease inhibitor (PI) use, introduction of an initial non-nucleoside reverse transcriptase inhibitor or the number of antiretroviral agents changed when nelfinavir was added, likely reflecting the homogeneity of the population studied. The only parameter predictive of response was virus genotype. Response rates were lower in patients with increasing numbers of primary (P=0.045) or secondary (P=0.001) PI mutations. The addition of increasing numbers of reverse transcriptase mutations further impaired response rates (P=0.004).