title: Virological efficacy of PI monotherapy for HIV-1 in clinical practice.
abstract: Clinical trials of PI monotherapy indicate that most participants maintain viral suppression and emergent protease resistance is rare. However, outcomes among patients receiving PI monotherapy for clinical reasons, such as toxicity or adherence issues, are less well studied.
  
  
  
  An observational study of patients attending an HIV treatment centre in London, UK, who had received PI monotherapy between 2004 and 2013, was conducted using prospectively collected clinical data and genotypic resistance reports. Survival analysis techniques were used to examine the times to virological failure and treatment discontinuation.
  
  
  
  Ninety-five patients had PI monotherapy treatment for a median duration of 126 weeks. Virological failure occurred during 64% of episodes and 8% of patients developed emergent protease mutations. We estimate failure occurs in half of episodes within 2 years following initiation. Where PI monotherapy was continued following virological failure, 68% of patients achieved viral re-suppression. Despite a high incidence of virological failure, many patients continued PI monotherapy and 79% of episodes were ongoing at the end of the study. The type of PI used, the presence of baseline protease mutations and the plasma HIV RNA at initiation did not have a significant impact on treatment outcomes.
  
  
  
  There was a higher incidence of virological failure and emerging resistance in our UK clinical setting than described in PI monotherapy clinical trials and other European observational studies. Despite this, many patients continued PI monotherapy and regained viral suppression, indicating this strategy remains a viable option in certain individuals following careful clinical evaluation.
authors.affiliation: Research Department of Infection, Division of Infection and Immunity, University College London, London, UK.|Research Department of Infection and Population Health, University College London, London, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: El Bouzidi
authors.affiliation: Research Department of Infection, Division of Infection and Immunity, University College London, London, UK.
authors.forename: Dami
authors.initials: D
authors.lastname: Collier
authors.affiliation: Research Department of Infection, Division of Infection and Immunity, University College London, London, UK.|Department of Clinical Virology, University College London Hospitals NHS Trust, London, UK.|NIHR University College London Hospitals Biomedical Research Centre, London, UK.
authors.forename: Eleni
authors.initials: E
authors.lastname: Nastouli
authors.affiliation: Research Department of Infection and Population Health, University College London, London, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Copas
authors.affiliation: Research Department of Infection and Population Health, University College London, London, UK.|Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Miller
authors.affiliation: Research Department of Infection, Division of Infection and Immunity, University College London, London, UK ravindra.gupta@ucl.ac.uk.
authors.forename: Ravindra K
authors.initials: RK
authors.lastname: Gupta
mesh_terms: D000293:Adolescent; D000328:Adult; D024882:Drug Resistance, Viral; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D015497:HIV-1 / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D008131:London; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D019562:Viral Load; D055815:Young Adult
chemical_list: D017320:HIV Protease Inhibitors