Update on clinical and methodological recommendations for genotypic determination of HIV tropism to guide the usage of CCR5 antagonists.

The genotypic determination of HIV tropism to guide the use of maraviroc, the first CCR5 antagonist with specific antiviral activity against CCR5 (R5)-tropic HIV variants, has been widespread in the last two years. Retrospective analyses from maraviroc clinical trials (MOTIVATE and MERIT) demonstrated that specific genotypic tools and the phenotypic assay TrofileTM are comparable in predicting virologic response to maraviroc. Moreover, recent studies performed in cohorts of patients outside clinical trials have reported overall rates of virologic response to maraviroc up to 82% in patients harboring HIV R5-tropic variants according to genotypic tools. Specific technical requirements as well as recommendations for proper HIV tropism determination in the clinical setting have been improving, according to new data reported in several studies related with this issue. This review updates clinical and methodological recommendations for genotypic determination of HIV tropism to guide therapeutic decisions using CCR5 antagonists, considering the most recently reported data.