Abstract
BackgroundClinical 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.MethodsAn 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.ResultsNinety-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.ConclusionsThere 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.
Highlights
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
Many patients continued PI monotherapy and regained viral suppression, indicating this strategy remains a viable option in certain individuals following careful clinical evaluation
PI monotherapy is an appealing option in a subset of patients for whom combination ART is unsuitable for clinical reasons, such as adverse effects associated with nucleoside reverse transcriptase inhibitors, interactions with other medication and adherence issues
Summary
PI monotherapy is an appealing option in a subset of patients for whom combination ART (cART) is unsuitable for clinical reasons, such as adverse effects associated with nucleoside reverse transcriptase inhibitors, interactions with other medication and adherence issues. Modern boosted PIs are good candidates for use as monotherapy as this class is known to have a high genetic barrier to resistance following viral failure, requiring several mutations before phenotypic drug susceptibility is significantly reduced.[1,2] In an era when patients will initiate treatment earlier and can expect to be taking therapy for decades, other potential advantages of PI monotherapy include the avoidance of toxicity and preservation of long-term treatment options.[3,4]. Randomized controlled trials investigating PI monotherapy as a maintenance strategy indicate that most participants maintain viral suppression and the emergence of resistance-associated protease mutations is rare. Clinical trials of PI monotherapy indicate that most participants maintain viral suppression and emergent protease resistance is rare. Outcomes among patients receiving PI monotherapy for clinical reasons, such as toxicity or adherence issues, are less well studied
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