Rilpivirine plus cobicistat-boosted darunavir as alternative to standard three-drug therapy in HIV-infected, virologically suppressed subjects: Final results of the PROBE 2 trial

Background Primary analysis at 24 weeks showed that switching to rilpivirine plus darunavir/cobicistat was non-inferior to continuing a standard three-drug antiretroviral regimen in virologically suppressed people with HIV. We present efficacy and safety data from the 48-week analysis. Methods PROBE 2 is a randomized, open-label trial. Adults who were on a three-drug therapy and had had <50 HIV-1 RNA copies/mL for at least 6 months were randomly assigned (1:1) to 25 mg rilpivirine plus 800/150 darunavir/cobicistat once daily (early switch group) or to continue their regimen for 24 weeks before switching (late switch group). In the 48-week analysis, the efficacy endpoint was the proportion of participants with <50 copies/mL of HIV-RNA (US Food and Drug Administration snapshot algorithm). The trial is registered with ClinicalTrials.gov , number NCT04064632. Findings 160 participants were recruited and randomized. At week 48, 70 (87.5%) in the early switch group and 76 (94.8%) in the late switch group maintained HIV-RNA <50 copies/mL. Virological failure (≥50 HIV-RNA copies/mL) was not seen in any patient of the early switch group and in 2 subjects in the late switch group none of which had treatment emergent resistance-associated mutation. Adverse events leading to treatment discontinuation occurred in 7 (8.7%) participants in the early switch group and in none in the late switch group. Interpretation The combination of rilpivirine plus darunavir/cobicistat sustained virological suppression, was associated with a low frequency of virological failure, and had a favorable safety profile, which support its use as a nucleoside reverse transcriptase inhibitor-sparing and integrase inhibitor-sparing alternative to three-drug regimens.