title: Characterization of virologic failure patients on darunavir/ritonavir in treatment-experienced patients.
abstract: OBJECTIVE
  Characterization of resistance development in virologic failure patients on the protease inhibitor darunavir administered with low-dose ritonavir (DRV/r) in the 48-week analysis of TMC114/r In Treatment-experienced pAtients Naive to lopinavir (TITAN).
  
  
  METHODS
  TITAN is a randomized, controlled, open-label, phase III, noninferiority trial comparing the efficacy and safety of DRV/r with that of lopinavir/ritonavir (LPV/r) in HIV-1-infected, treatment-experienced, LPV-naive patients. The primary endpoint was the proportion of patients with HIV-1 RNA less than 400 copies/ml at week 48.
  
  
  METHODS
  Patients received DRV/r 600/100 mg twice daily (n = 298) or LPV/r 400/100 mg twice daily (n = 297), and an optimized background regimen. Patients who lost or never achieved HIV-1 RNA less than 400 copies/ml after week 16 were considered virologic failure patients. Genotyping and phenotyping were performed.
  
  
  RESULTS
  The virologic failure rate in the DRV/r arm (10%, n = 31) was lower than in the LPV/r arm (22%, n = 65). Furthermore, fewer virologic failure patients in the DRV/r arm than in the LPV/r arm developed primary protease inhibitor mutations (6 vs. 20) or nucleoside reverse transcriptase inhibitor resistance-associated mutations (4 vs. 15). In addition, fewer virologic failure patients on DRV/r than on LPV/r lost susceptibility to the protease inhibitor (3 vs. 13) or nucleoside reverse transcriptase inhibitor(s) (3 vs. 14) used in the treatment regimen or to other protease inhibitors. Most DRV/r-treated virologic failure patients retained susceptibility to all protease inhibitors.
  
  
  CONCLUSIONS
  In treatment-experienced, LPV-naive patients, the overall virologic failure rate in the DRV/r arm was low and was associated with limited resistance development. These findings showed that the use of DRV/r in earlier lines of treatment was less likely to lead to cross-resistance to other protease inhibitors compared with LPV/r.
authors.affiliation: Tibotec BVBA, Mechelen, Belgium bJanssen-Cilag BV, Amsterdam, The Netherlands. sdmeyer@its.jnj.com
authors.forename: Sandra
authors.initials: S
authors.lastname: De Meyer
authors.forename: Erkki
authors.initials: E
authors.lastname: Lathouwers
authors.forename: Inge
authors.initials: I
authors.lastname: Dierynck
authors.forename: Els
authors.initials: E
authors.lastname: De Paepe
authors.forename: Ben
authors.initials: B
authors.lastname: Van Baelen
authors.forename: Tony
authors.initials: T
authors.lastname: Vangeneugden
authors.forename: Sabrina
authors.initials: S
authors.lastname: Spinosa-Guzman
authors.forename: Eric
authors.initials: E
authors.lastname: Lefebvre
authors.forename: Gaston
authors.initials: G
authors.lastname: Picchio
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: de Béthune
mesh_terms: D019380:Anti-HIV Agents / Q000627:therapeutic use; D000069454:Darunavir; D024921:Drug Resistance, Multiple, Viral / Q000235:genetics; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D061466:Lopinavir; D009154:Mutation; D011744:Pyrimidinones / Q000627:therapeutic use; D012367:RNA, Viral / Q000097:blood; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use; D019438:Ritonavir / Q000627:therapeutic use*; D013449:Sulfonamides / Q000627:therapeutic use*; D017211:Treatment Failure; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; D013449:Sulfonamides; D061466:Lopinavir; D019438:Ritonavir; D000069454:Darunavir