Switching to doravirine-based antiretroviral therapy without genotypic resistance tests in virologically suppressed people with HIV

BACKGROUND: Doravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) recommended for first-line antiretroviral therapy (ART), and for suppressed switching, in combination with a two nucleos(t)ide reverse transcriptase inhibitor (NRTI) backbone. Doravirine does not have a high barrier to resistance, and genotypic resistance testing (GRT) pre-switch is recommended. Data on its use without pre-switching GRT is limited. This retrospective cohort study presents data on doravirine use in virologically suppressed people with and without prior GRT. METHODS: A retrospective single centre review of health records was conducted among prescribed doravirine-based ART at a London HIV service. RESULTS: Of the 582 adults included, 75% were men, 56% were of White ethnicity. The median age at baseline was 51-years (IQR: 44-58). Median time on doravirine was 127-weeks (IQR:93-175). GRT showing no doravirine resistance was available for 78% (n = 454) of individuals before switching to doravirine, of which, 2% experienced virological failure (n = 9); including two people with NNRTI and NRTI resistance. Among those without pre-switching GRT (n = 97), 1% experienced virological failure (n = 1), with NNRTI and NRTI resistance. There was no statistical significant difference in virologic suppression (viral load <50 copies/ml) rates (GRT 95% versus no-GRT 95%; p = 0.823). A similar proportion of people with (24%) and without (27%) pre-switching GRT switched away from doravirine, most commonly due to adverse effects. CONCLUSIONS: We did not find differences in efficacy and tolerability in people switched to doravirine-based ART with or without GRT. As expected, emergent NNRTI and NRTI resistance was common amongst those with virological failure on doravirine.