title: Maraviroc observational study: the impact of expanded resistance testing and clinical considerations for antiretroviral regimen selection in treatment-experienced patients.
abstract: Maraviroc (MVC) use has trailed that of other post-2006 antiretroviral therapy (ART) options for treatment-experienced patients. We explored the impact of free tropism testing on MVC utilization in our cohort and explored barriers to MVC utilization. The Maraviroc Outcomes Study (MOS) is an investigator-initiated industry-sponsored trial where consecutive ART-experienced patients receiving routine care with viral loads ≥1,000 copies/ml, and whose provider requested resistance testing and received standardized resistance testing (SRT; phenotype, genotype, coreceptor/tropism). Sociodemographic, clinical, and ART characteristics of those receiving SRT were compared to a historical cohort (HC). Subsequently, providers were surveyed regarding factors influencing selection of salvage ART therapy. The HC (n=165) had resistance testing 7/08-9/09, while prospective SRT (n=83) patients were enrolled 9/09-8/10. In the HC, 92% had genotypes, 2% had tropism assays, and 62% (n=102) changed ART after resistance testing (raltegravir 37%, etravirine 25%, darunavir 24%, MVC 1%). In the SRT cohort, 57% (n=48) changed regimens after standardized resistance testing (darunavir 48%, raltegravir 40%, and etravirine 19%). CCR5-tropic virus was identified in 43% of the SRT group, and MVC was used in 10% [or 20% of R5 tropic patients who underwent a subsequent regimen change (n=25)], a statistically significant (p=0.01) increase in utilization. The factors most strongly influencing utilization were unique patient circumstances (60%), clinical experience (55%), and potential side effects (40%). The addition of routine tropism testing to genotypic/phenotypic testing was associated with increased MVC utilization, raising the possibility that tropism testing may present a barrier to MVC use; however, additional barriers exist, and merit further evaluation.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL 35294, USA. jwillig@uab.edu
authors.forename: James H
authors.initials: JH
authors.lastname: Willig
authors.forename: Sara-Anne
authors.initials: SA
authors.lastname: Wilkins
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Tamhane
authors.forename: Christa R
authors.initials: CR
authors.lastname: Nevin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mugavero
authors.forename: James L
authors.initials: JL
authors.lastname: Raper
authors.forename: Laura A
authors.initials: LA
authors.lastname: Napolitano
authors.forename: Michael S
authors.initials: MS
authors.lastname: Saag
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D003510:Cyclohexanes / Q000627:therapeutic use*; D024882:Drug Resistance, Viral; D006678:HIV / Q000187:drug effects; D023581:HIV Fusion Inhibitors / Q000627:therapeutic use*; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D008297:Male; D000077592:Maraviroc; D008826:Microbial Sensitivity Tests; D016879:Salvage Therapy / Q000379:methods; D017211:Treatment Failure; D014230:Triazoles / Q000627:therapeutic use*
chemical_list: D019380:Anti-HIV Agents; D003510:Cyclohexanes; D023581:HIV Fusion Inhibitors; D014230:Triazoles; D000077592:Maraviroc