title: Dynamic patterns of human immunodeficiency virus type 1 integrase gene evolution in patients failing raltegravir-based salvage therapies.
abstract: OBJECTIVE
  : Evaluate HIV-1 subtype B integrase gene evolution in patients failing raltegravir (RAL)-based savage regimens by clonal analysis of the replicating viral quasispecies.
  
  
  METHODS
  : Seven triple class failure HIV-1 (subtype B)-infected patients, followed at San Raffaele Hospital and enrolled in the RAL Expanded Access Program (MK0518-023), were evaluated. Patients were followed up for 24-48 weeks and due to the absence of other active drugs, RAL was maintained in their regimens even if resistance mutations were detected.
  
  
  METHODS
  : Immunologic and virologic parameters were recorded every 4 weeks, and amplification and clonal analysis of viral populations were performed at baseline and every 4-12 weeks in all patients.
  
  
  RESULTS
  : Resistance to RAL appeared initially associated with selection of single variants (Y143R, Q148R N155H) in the majority of patients; however, in three patients, complex patterns of viral mutations were observed. The clonal analysis of viral quasispecies allowed to describe the evolution of each viral population and the progressive accumulation of RAL resistance-associated mutations and polymorphisms associated with therapy failure.
  
  
  CONCLUSIONS
  : The complex patterns of resistance mutations observed, including novel variants evolved under continuous RAL pressure, suggesting that they are the result of the equilibrium between drug resistance and enzyme function. Despite the efficacy of this compound, our data discourage its use in a functional monotherapy and maintaining RAL even in presence of RAL resistance-associated mutations may lead to the progressive formation of viral reservoirs with multiple integrase inhibitor-resistant variants that may limit the future efficacy of other integrase inhibitors due to cross-resistance.
authors.affiliation: Università Vita-Salute San Raffaele, Italy. canducci.filippo@hsr.it
authors.forename: Filippo
authors.initials: F
authors.lastname: Canducci
authors.forename: Michela
authors.initials: M
authors.lastname: Sampaolo
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Marinozzi
authors.forename: Enzo
authors.initials: E
authors.lastname: Boeri
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Spagnuolo
authors.forename: Andrea
authors.initials: A
authors.lastname: Galli
authors.forename: Antonella
authors.initials: A
authors.lastname: Castagna
authors.forename: Adriano
authors.initials: A
authors.lastname: Lazzarin
authors.forename: Massimo
authors.initials: M
authors.lastname: Clementi
authors.forename: Nicola
authors.initials: N
authors.lastname: Gianotti
mesh_terms: D018791:CD4 Lymphocyte Count; D024882:Drug Resistance, Viral / Q000235:genetics*; D019143:Evolution, Molecular; D005500:Follow-Up Studies; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D019427:HIV Integrase / Q000235:genetics*; D019428:HIV Integrase Inhibitors / Q000627:therapeutic use*; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D009154:Mutation; D011760:Pyrrolidinones / Q000627:therapeutic use*; D000068898:Raltegravir Potassium; D019562:Viral Load
chemical_list: D019428:HIV Integrase Inhibitors; D011760:Pyrrolidinones; D000068898:Raltegravir Potassium; D019427:HIV Integrase; C514801:p31 integrase protein, Human immunodeficiency virus 1