Previous treatment failure
on an NRTI-containing regimen has been associated with an increased risk of virological failure when switching from a PI to an NNRTI-based regimen [7]. A recent cohort analysis showed similar rates of virological failure at 12 months in patients switching from a first-line PI/r to either EFV or NVP compared with continuing on the PI/r [8]. If switching to NVP, consideration should be given to the risk of hypersensitivity reactions and hepatotoxicity. Similar rates have been reported in virologically suppressed compared with ART-naïve patients stratified for CD4 cell count and gender [9, 10]. For patients without previous NRTI or NNRTI resistance mutations switching from a PI/r to any of the current licensed NNRTIs is likely Talazoparib to maintain virological efficacy and choice of NNRTI will depend on side effect profile, tolerability and patient preference. Switching from a PI/r to the INI, RAL, in virologically suppressed patients has been evaluated in three RCTs.
Two studies have shown that previous history of NRTI resistance mutations increases the risk of subsequent virological failure on switching compared with continuing on a PI/r [11, 12]. This association was not seen in a third trial [13]. However, it is not surprising that switching from an ARV with a high genetic barrier to one with a low genetic barrier to resistance may see more potentially increase the risk of virological failure if the activity of the NRTI backbone has been compromised by previous NRTI resistance. There are limited data on switching
from an NNRTI to an alternative third agent in virologically suppressed patients; however, consideration must be given to previous treatment history and potential pharmacokinetic interactions. The latter is discussed in more detail in Section 6.2.4 (Switching therapy: pharmacological considerations). We recommend continuing standard combination ART as the maintenance strategy in virologically suppressed patients (1C). (There are insufficient data to recommend PI/r monotherapy in this clinical situation.) Number of patients on PI/r monotherapy as ART maintenance strategy in virologically suppressed patients and record of rationale. For the assessment and evaluation of evidence, GRADE tables were constructed (Appendix 3). Virological suppression, drug resistance Alanine-glyoxylate transaminase and serious adverse events were defined as critical outcomes. From the systematic literature review (Appendix 2) 10 RCTs were identified, investigating the use of either LPV/r or DRV/r in stable, virologically suppressed patients without active hepatitis B coinfection [1-13]. Assessment of virological suppression showed significantly fewer patients on PI monotherapy maintaining virological suppression compared with those continuing on standard combination ART (RR 0.95, 95% CI 0.9, 0.99), although the difference was small. A similar result has previously been reported in a meta-analysis [14].