Use of PCR Signal and Therapeutic Drug Monitoring in a Switch Cohort Study to Tenofovir/Emtricitabine/Rilpivirine: A W96 Follow-Up

OBJECTIVE: To assess, in a clinical cohort, the efficacy of switching treatment in virologically-suppressed patients to tenofovir/emtricitabine/rilpivirine as a single-tablet regimen (STR) using the PCR signal of the viral load (VL) assay and plasma drug determination (C24h). PATIENTS AND METHODS: An observational single-centre study enrolling patients with VL<50 copies/mL initiating rilpivirine-based STR. C24h and VL were performed until W48 and W96 of STR, respectively. PCRneg was defined as an undetected PCR signal. Medians (IQR) were presented. RESULTS: 116 patients were enrolled. At STR baseline, time since first antiretroviral therapy and time of virological suppression were 6 years (2–9) and 17 months (7–43), respectively. Before STR initiation, patients were receiving protease inhibitors and non-nucleoside reverse transcriptase inhibitors-based regimen in 44% and 47% of cases, respectively. Historical genotype showed virus resistant to one drug of the STR in 6 patients (5%). At W96, 17 (15%) discontinued STR due to adverse events. The proportion of patients maintaining VL <50 copies/mL on treatment was 98%, 99%, 100%, 100%, 100% and 100% at W12, W24, W36, W48, W72 and W96, respectively. Among them, 70%, 66%, 68%, 59%, 74%, 68% and 60% were PCRneg at baseline, W12, W24, W36, W48, W72 and W96, respectively. Median rilpivirine C24h was 91 ng/mL (57–141, n = 285), with 91% of rilpivirine C24h >50 ng/mL, the target effective concentration. CONCLUSIONS: In this clinical cohort of virologically-suppressed patients switching to a new STR, most subjects had adequate rilpivirine C24h and displayed a high level of virological suppression with no residual viremia until W96.