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Background: Nonacog alfa, a standard half-life recombinant factor IX (FIX), is used as a prophylactic treatment in severe haemophilia B (SHB) patients. Its half-life determined in clinical studies involving a limited sampling (72 h) was shown to be rather short. In our clinical practice, we suspected that its half-life could have been underestimated., Objectives: We aimed to evaluate nonacog alfa pharmacokinetics in real world clinical practice based on FIX levels in patients receiving prophylaxis., Methods: We retrospectively collected data on patients with SHB receiving prophylaxis from eight centres across France. The terminal half-life (THL), time to reach 5-2 IU/dl and FIX activity at 48, 72 and 96 h were derived by Bayesian estimations using NONMEM analysis., Results and Conclusions: Infusion data (n = 455) were collected from 64 patients with SHB. The median THL measured in 92 pharmacokinetic (PK) studies was 43.4 h. In 26 patients ≤12 years of age, 51 PK studies showed a median time to reach 5 IU/dl of FIX of 70.5 h and a median time to reach 2 IU/dl of 121.5 h. In 38 patients 13-75 years of age, 41 PK studies showed a median time to reach 5 IU/dl of FIX of 92.0 h and a median time to reach 2 IU/dl of 167.5 h. Extending the sampling beyond 72 h makes it possible to observe a plateau, with FIX remaining between 2 and 5 IU/dl for several days and shows that the THL of nonacog alfa might be longer than previously described., Essentials: Nonacog alfa terminal half-life (THL) in patients receiving regular prophylaxis was evaluated in clinical practice. The median THL was estimated to be 36.9 h for patients aged .8-12 years. The median THL was estimated to be 49.9 h for patients aged 13-75 years. For patients aged ≤12 and >12 years, the median times to reach 5 IU/dl were 70.5 and 92 h, respectively; to reach 3 IU/dl, 95.5 and 131.5 h, respectively; to reach 2 IU/dl, 121.5 and 167.5 h, respectively. We suggest that the half-life of nonacog alfa might be longer than previously described in both younger and older patients., (© 2022 John Wiley & Sons Ltd.)

Background: The Web-Accessible Population Pharmacokinetic Service (WAPPS) project generates individually predicted pharmacokinetic (PK) profiles and tailored prophylactic treatment regimens for haemophilic patients, which rely on a set of population PK (PopPK) models providing concentrate-specific priors for the Bayesian forecasting methodology., Aim: To describe the predictive performance of the WAPPS PopPK models in use on the WAPPS-Hemo platform., Methods: Data for modelling include dense PK data obtained from industry sponsored and independent PK studies, and dense and sparse data accumulated through WAPPS-Hemo. WAPPS PopPK models were developed via non-linear mixed-effect modelling taking into account the effects of covariates and between-individual-and sometimes between-occasion-variability. Model evaluation consisted of (a) prediction-corrected Visual Predictive Check (pcVPC), (b) Limited Sampling Analysis (LSA) and (c) repeated hold-out cross-validation., Results: Thirty-three WAPPS PopPK models built on data from 3188 patients (ages 1-78 years) under treatment by factor VIII or IX products (FVIII, FIX) were evaluated. Overall, models exhibit excellent performance characteristics. The pcVPC shows that the observed PK data fall within acceptable 90% interpercentile predictive bands. A slight overprediction beyond the expected half-life, an anticipated result of using sparse data, occurs for some models. The LSA results in lower than 3% of relative error for FVIII and FIX products and 16% for engineered FIX products. Cross-Validation analysis yields relative errors lower than 1.5% and 1.4% in estimates of half-life and time to 0.02 IU/mL, respectively., Conclusion: The WAPPS-Hemo models consistently showed excellent performance characteristics for the intended use for Bayesian forecasting of individual PK profiles., (© 2020 John Wiley & Sons Ltd.)

Introduction: Web‐Accessible Population–Pharmacokinetic Service–Haemophilia (WAPPS‐Hemo) data are available to study factor‐concentrate usage, defined as the required weekly dose to achieve a 3% trough (WD3T), across standard and extended half‐life (SHL/EHL) products. Aim: To provide baseline usage data including (i) differences across plasma‐derived (pdSHL) versus recombinant (rSHL) products, (ii) SHL versus EHL, and (iii) effect of age and positive inhibitor history. Methods: PK profiles (n = 14,416 patients, 0.3–85.2 years) and linear mixed effects models were used to estimate usage versus age, controlling for significant factors, using 95% confidence intervals to perform comparisons across all ages and posthoc tests to assess the differences. Results: Average usage was significantly higher for pdSHL versus rSHL in patients with a positive inhibitor history (PIH; 1.9–2.5 times higher), for SHL versus EHL (4–10 times), and was significantly associated with age. Conclusion: Baseline usage patterns from 2017 to early 2023 provide a benchmark for assessing the impact of emerging technologies in haemophilia. [ABSTRACT FROM AUTHOR]