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.