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Background: Tocilizumab prevents the clinical worsening of chronic active antibody-mediated rejection (CAAMR) in kidney transplant recipients. Following a global shortage of the intravenous pharmaceutical form in 2022, patients were switched from monthly intravenous administration of 8 mg/kg to weekly subcutaneous injection of 162 mg, raising the question of bioequivalence between these schemes of administration., Aims: We aimed to compare the areas under the curve (AUC) of tocilizumab in virtual simulations of populations treated with the two administration schemes and to identify the covariates that could contribute to pharmacokinetic variability of tocilizumab in kidney transplant patients with CAAMR who received tocilizumab as salvage treatment., Methods: This retrospective monocentric study included 43 kidney transplant patients (202 tocilizumab concentrations) with CAAMR treated with intravenous or subcutaneous tocilizumab between December 2020 and January 2023. We developed a population pharmacokinetic model using nonlinear mixed effects modeling and identified the covariates that could contribute to tocilizumab AUC variability. Monte Carlo simulations were then performed to assess the subcutaneous and intravenous tocilizumab AUC for 0-28 days (M1), 56-84 days (M3), 140-168 days (M6), and 308-336 days (M12). Bioequivalence was defined by SC/IV AUC geometric mean ratios (GMRs) between 0.80 and 1.25., Results: A two-compartment model with parallel linear and nonlinear elimination best described the concentration-time data. Significant covariates for tocilizumab clearance were body weight, urinary albumin-to-creatinine ratio (ACR), and inflammation status [C-reactive protein (CRP) ≥ 5 mg/L]. The GMR values and their 90% confidence intervals at M3, M6, and M12 were within the 0.8-1.25 margin for equivalence. Conversely, the 90% prediction intervals of the GMR were much wider than the 90% confidence intervals and did not fall within 0.8 and 1.25., Conclusions: From month 3 of treatment, the subcutaneous and intravenous tocilizumab administration schemes provided average bioequivalent pharmacokinetic exposure at the population level but not at the individual level. Body weight, inflammation, ACR, and administration scheme should be considered to personalize the dose of tocilizumab for patients with CAAMR. Further studies are required to determine the target of tocilizumab exposure in kidney transplant patients with CAAMR., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Tocilizumab prevents clinical worsening of chronic antibody-mediated rejection (CAMR) of kidney transplant recipients. Optimization of this treatment is necessary. We identified the determinants of early tocilizumab exposure (within the first three months) and investigated the relationship between early plasma tocilizumab exposure and graft function. Patients with CAMR who started treatment with tocilizumab were retrospectively included. Demographic, clinical, and biological determinants of the tocilizumab trough concentration (C min ) were studied using a linear mixed effect model, and the association between early exposure to tocilizumab (expressed as the sum of C min over the three first months (M) of treatment (ΣC min )) and the urinary albumin-to-creatinine ratio (ACR) determined at M3 and M6 were investigated. Urinary tocilizumab was also measured in seven additional patients. Seventeen patients with 51 tocilizumab C min determinations were included. In the multivariate analysis, the ACR and time after tocilizumab initiation were independently associated with the tocilizumab C min . The ΣC min was significantly lower ( p = 0.014) for patients with an ACR > 30 mg/mmol at M3 and M6 than for patients with an ACR < 30 mg/mmol. Tocilizumab was detected in urine in only 1/7 patients. This study is the first to suggest that early exposure to tocilizumab may be associated with macroalbuminuria within the first six months in CAMR patients.

High-sensitivity troponin has become an essential emergency biomarker for diagnosing or ruling out an ACS. The establishment of a point of care biology related to the reorganization and fusion of laboratories raise a question about transferability of results between techniques. In this study, we propose to compare the bioclinical performances of high-sensitivity troponin measured by two different techniques on laboratory immunoanalyzer (Siemens Advia Centaur XPT) and on point of care device (Mitsubishi Pathfast). The assay of high-sensitivity troponin (n = 90 patients), according to our study, show consistent clinical results with both method.

Over the last two decades, organic photovoltaic (OPV) devices have seen their efficiency increase, while long-term stability and upscaling have been demonstrated for first-generation modules. Since the maturity level of this technology has now improved, techniques for rapid quality control have become relevant. Imaging techniques such as photo- and electroluminescence have already been used for this purpose. However, defects could only be localized either in the active layer or in interface layers, without being able to distinguish between defects located in the ETL from those within the HTL. Here, we present a simple method to unambiguously discriminate between ETL and HTL defects. Furthermore, we demonstrate the strong impact of HTL thickness on the detected photoluminescence signal. Our approach will help avoid misinterpretations in luminescence experiments and gain an understanding of device failure during processing or aging.