Long-term data from the nevirapine/efavirenz/abacavir (NEFA) study demonstrated that patients who switched from a protease inhibitor (PI)-based regimen to a non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimen containing nevirapine (Viramune) or efavirenz achieved comparable efficacy and safety to their previous regimen and were more likely to maintain virological suppression after three years of follow-up than patients who switched to an abacavir-containing regimen.
The NEFA study, a multicentre, randomised, open-label clinical trial, is the largest prospective PI switch study conducted to date. The study was initially designed for one-year follow-up of 460 HIV-positive adults who had previously been treated with at least one PI plus two nucleoside reverse transcriptase inhibitors (NRTIs). Follow-up was extended to three years following recommendations from the CHMP of the EMEA. Patients enrolled were required to have maintained the amount of HIV in their blood (viral load) to less than 200 copies/ml for at least six months on their PI-based regimen containing indinavir, nelfinavir, ritonavir, saquinavir, indinavir or saquinavir in combination with low-dose ritonavir prior to study entry. Patients were then randomised to replace their PI with nevirapine twice daily, efavirenz once daily or abacavir twice daily.
Intent-to-treat analysis of patients originally randomised to switch from their PI to nevirapine, efavirenz or abacavir showed that 93.5% of patients who switched to nevirapine, 92.9% of patients who switched to efavirenz and 80.5% of patients who switched to abavacir achieved virological success after three years.