Before starting maraviroc in a treatment-experienced HIV positive patient, which laboratory test is mandatory?

• A HLA-B*5702 typing
• B Baseline CD8 count and beta-2 microglobulin level
• C Quantitative HIV RNA with genotypic integrase sequencing
• D Viral tropism assay to confirm exclusive CCR5 usage ✓

Explanation

Maraviroc blocks the CCR5 co-receptor, so it works only against viruses that enter cells through CCR5. If the circulating quasispecies includes CXCR4 tropic virus, maraviroc is ineffective and may select for rapid outgrowth of CXCR4 strains, as seen in the MOTIVATE trials context. Hence a tropism assay is required before initiation. HLA-D*5701 typing relates to abacavir hypersensitivity, not maraviroc.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.