HIV-1 resistance patterns to integrase inhibitors in antiretroviral-experienced patients with virological failure on raltegravir-containing regimens.

BACKGROUND: Our aim was to study the in vivo viral genetic pathways for resistance to raltegravir, in antiretroviral-experienced patients with virological failure (VF) on raltegravir-containing regimens.
METHODS: We set up a prospective study including antiretroviral-experienced patients receiving raltegravir-based regimens. Integrase (IN) genotypic resistance analysis was performed at baseline. IN was also sequenced at follow-up points in the case of VF, i.e. plasma HIV-1 RNA>400 copies/mL at month 3 and/or >50 copies/mL at month 6. For phenotyping, the IN region was recombined with an IN-deleted HXB2-based HIV-1 backbone. A titrated amount of IN recombinant viruses was used for antiviral testing against raltegravir and elvitegravir.
RESULTS: Among 51 patients, 11 (21.6%) had VF. Four different patterns of IN mutations were observed: (i) emergence of Q148H/R with secondary mutations (n=5 patients); (ii) emergence of N155H, then replaced by a pattern including Y143C/H/R (n=3); (iii) selection of S230N (n=1); and (iv) no evidence of selection of IN mutations (n=2). The median raltegravir and elvitegravir fold changes (FCs) were 244 (154-647) and 793 (339-892), respectively, for the Q148H/R pattern, while the median raltegravir and elvitegravir FCs were 21 (6-52) and 3 (2-3), respectively, with Y143C/H/R. The median plasma raltegravir Cmin was lower in patients with selection of the N155H mutation followed by Y143C/H/R compared with patients with Q148H/R and with patients without emerging mutations or without VF.
CONCLUSIONS: Diverse genetic profiles can be associated with VF on raltegravir-containing regimens, including the dynamics of replacement of mutational profiles. Pharmacokinetic parameters could be involved in this genetic evolution.