Drug resistance profiles for the HIV integrase gene in patients failing raltegravir salvage therapy.

Objectives: Recent data showed the selection of mutations in the integrase gene, mainly involving position 148 or 155, in patients displaying virological failure (VF) on raltegravir (RAL) therapy. Here, we describe the development of RAL resistance, in both plasmatic and cellular compartments, in three heavily pretreated HIV-infected patients failing RAL-containing regimens.

Methods: Three of 17 patients receiving RAL displayed VF. The entire integrase gene, isolated from plasma and peripheral blood mononuclear cells (PBMC), was sequenced. A clonal analysis was performed in one patient at the time of VF.

Results: At the time of VF, RAL-resistance mutations were selected: (i) Q148R in patients 1 and 3; (ii) T66A and E92Q in patient 2. A gradual accumulation of new mutations was observed in all patients, including G140S, Q148H and N155H in patient 1, L74I in patient 2, and G140S in patient 3. Clonal analysis showed the coexistence, in patient 1, of the two common resistance pathways (mutations Q148R/H and N155H) found in distinct quasi-species. In addition, RAL-resistance mutations were detected in HIV DNA in all patients.

Conclusions: Having rapidly established, resistance to RAL evolves and diversifies, and is likely to impact the efficacy of subsequently used second-generation integrase inhibitors. Moreover, RAL-resistance mutations can be archived early in PBMC.