Limited sampling strategies for individualized BAX 855 prophylaxis in severe hemophilia A:in silico evaluation

ObjectiveLimited sampling strategies (LSS) lower the burden of pharmacokinetic (PK)-guided dosing, but an extensive evaluation of LSS for BAX 855 (Adynovi) is currently lacking. This study aimed to develop a LSS for BAX 855 and combine this with a LSS of a standard half-life (SHL) factor VIII (FVIII) concentrate in a clinical setting.MethodsIndividual PK parameters of BAX 855 were estimated for 10 000 virtual patients with severe hemophilia A using Monte Carlo simulations. Several LSS consisting of 2-6 samples were examined based on patient burden, bias and accuracy of clearance, elimination half-life, volume of distribution and trough levels at 72 h (C72). Analyses were performed separately for adults and children &lt;12 years.ResultsThe preferred LSS for BAX 855 consisted of three sampling points at 15-30 min, 48 h and 72 h for both adults (mean accuracy C72: 14.0% vs. 10.8% using six samples) and children (mean accuracy C72: 14.9% vs. 11.4% using six samples). The best strategy with two samples (peak, 48 h) resulted in an adequate, but lower accuracy than strategies with ≥3 samples (mean accuracy C72: 22.3%). The optimal combination of the LSS of SHL FVIII and BAX 855 led to six samples during four clinical visits.ConclusionThis in silico study has identified that two to three samples are necessary to estimate the individual PK of BAX-855 adequately. These samples can be collected in one or two clinical visits. When combining PK profiling of SHL FVIII and BAX 855, six samples during four clinical visits are needed.</p

Does difference between label and actual potency of factor VIII concentrate affect pharmacokinetic-guided dosing of replacement therapy in haemophilia A?

BACKGROUND: To account for interindividual variability in the pharmacokinetics (PK) of factor concentrates, PK‐guided dosing is increasingly implemented in haemophilia patients. Calculations are based on provided label potency, but legislation allows a potency difference of ±20% between label and actual potency. It is unknown if these differences affect PK guidance. AIM: Explore the effects of potency differences on individual factor VIII (FVIII) PK parameters and the prediction of FVIII trough levels of dosing regimens. METHODS: We analyzed individual preoperative PK profiling data from severe and moderate haemophilia A patients included in the OPTI‐CLOT randomized controlled trial. Label and actual potency were compared, with data on potency provided by pharmaceutical companies. For both potencies, individual PK parameters were estimated and concentration‐time curves were constructed by nonlinear mixed‐effects modelling. Finally, we explored the effect of both the identified and the maximum legislated potency difference on predicted FVIII trough levels infused in a low and high dose regimen. RESULTS: In 45/50 included patients, actual potency was higher than its label potency. The median potency difference was 6.0% (range ‐9.2% to 18.4%) and resulted in varying individual PK parameter estimates but practically identical FVIII concentration‐time curves. As expected, predicted FVIII trough levels were linearly correlated to the actual dose. CONCLUSION: It is not necessary to take potency differences into account when applying PK guidance of FVIII concentrates in haemophilia A patients. However, when the patient is switched to another FVIII batch after PK‐guided dosing, trough levels may deviate ±20% from calculations based on label dose

The value of sorafenib trough levels in patients with advanced hepatocellular carcinoma - a substudy of the SORAMIC trial.

Background: Sorafenib for advanced hepatocellular carcinoma (HCC) is dose adjusted by toxicity. Preliminary studies have suggested an association between plasma concentrations of sorafenib and its main metabolite (M2) and clinical outcomes. This study aimed to validate these findings and establish target values for sorafenib trough concentrations.Methods: Patients with advanced HCC were prospectively recruited within a multicenter phase II study (SORAMIC). Patients with blood samples available at trough level were included for this pharmacokinetic (PK) substudy. Trough plasma concentrations of sorafenib and its main metabolite (M2) were associated with sorafenib-related toxicity and overall survival (OS).Results: Seventy-four patients were included with a median OS of 19.7 months (95% CI 16.1-23.3). Patients received sorafenib for a median of 51 weeks (IQR 27-62) and blood samples were drawn after a median of 25 weeks (IQR 10-42). Patients had a median trough concentration of 3217 ng/ml (IQR 2166-4526) and 360 ng/ml (IQR 190-593) with coefficients of variation of 65% and 146% for sorafenib and M2, respectively. Patients who experienced severe sorafenib-related toxicity received a lower average daily dose (551 vs 730 mg/day, p = .003), but showed no significant differences in sorafenib (3298 vs 2915 ng/ml, p = .442) or M2 trough levels (428 vs 283 ng/ml, p = .159). Trough levels of sorafenib or M2 showed no significant association with OS.Conclusions: In patients with advanced HCC treated with sorafenib, the administered dose, trough levels of sorafenib or M2, and clinical outcomes were poorly correlated. Toxicity-adjusted dosing remains the standard for sorafenib treatment

DosEmi study protocol: a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of pharmacokinetic-guided reduced dosing compared with conventional dosing of emicizumab in people with haemophilia A

INTRODUCTION: Emicizumab effectively prevents bleeding in people with haemophilia A (PwHA), but is a burden for national healthcare budgets and consequently may limit access. According to the drug label, dosing of emicizumab is based on body weight with fixed intervals of 7, 14 or 28 days, which leads to mean plasma concentrations of 55 µg/mL (SD 15 µg/mL). However, a moderate variability of concentrations and a minimal effective concentration of 30 µg/mL have been suggested in studies. Therefore, a dose of emicizumab that targets a trough concentration of 30 µg/mL is hypothesised to be equally effective as conventional dosing in the prevention of bleeding. METHODS AND ANALYSIS: We designed a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of bleed control of ≥6 months on conventional dosing in comparison to ≥6 months on dose intervention. This dose intervention consists of reducing the dose of emicizumab to target a trough concentrations of 30 µg/mL using individual pharmacokinetic (PK) parameters. Ninety-five PwHA aged >1 years who received conventional dosing of emicizumab for ≥12 months with good bleeding control during the last 6 months will be recruited from all Dutch haemophilia treatment centres. The study is powered to detect a clinically relevant decrease (risk difference) of 15% in the proportion of patients without treated bleeds during follow-up. Secondary endpoints are spontaneous joint or muscle bleeds, and annualised treated bleeding rates (using negative binomial regression). Cost-effectivity between conventional dosing and individualised PK-guided dosing of emicizumab will be compared. ETHICS AND DISSEMINATION: The DosEmi study was approved by the Medical Ethics Review Committee NedMec of the University Medical Center of Utrecht, The Netherlands. Study results will be communicated through publications in international scientific journals and presentations at (inter)national conferences. TRIAL REGISTRATION NUMBER: EUCTR2021-004039-10-NL at https://trialsearch.who.int. PROTOCOL VERSION: V.4.1 on 28 October 2022 (DosEmi protocol_V4.1; NL81112.041.22)

Population Pharmacokinetics and Dosing Optimization of Ceftazidime in Term Asphyxiated Neonates during Controlled Therapeutic Hypothermia

Ceftazidime is an antibiotic commonly used to treat bacterial infections in term neonates undergoing controlled therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy after perinatal asphyxia. We aimed to describe the population pharmacokinetics (PK) of ceftazidime in asphyxiated neonates during hypothermia, rewarming, and normothermia and propose a population-based rational dosing regimen with optimal PK/pharmacodynamic (PD) target attainment. Data were collected in the PharmaCool prospective observational multicenter study. A population PK model was constructed, and the probability of target attainment (PTA) was assessed during all phases of controlled TH using targets of 100% of the time that the concentration in the blood exceeds the MIC (T.MIC) (for efficacy purposes and 100% T.4×MIC and 100% T.5×MIC to prevent resistance). A total of 35 patients with 338 ceftazidime concentrations were included. An allometrically scaled one-compartment model with postnatal age and body temperature as covariates on clearance was constructed. For a typical patient receiving the current dose of 100 mg/kg of body weight/day in 2 doses and assuming a worst-case MIC of 8 mg/L for Pseudomonas aeruginosa, the PTA was 99.7% for 100% T.MIC during hypothermia (33.7°C; postnatal age [PNA] of 2 days). The PTA decreased to 87.7% for 100% T.MIC during normothermia (36.7°C; PNA of 5 days). Therefore, a dosing regimen of 100 mg/kg/day in 2 doses during hypothermia and rewarming and 150 mg/kg/day in 3 doses during the following normothermic phase is advised. Higher-dosing regimens (150 mg/kg/day in 3 doses during hypothermia and 200 mg/kg/day in 4 doses during normothermia) could be considered when achievements of 100% T.4×MIC and 100% T.5×MIC are desired.</p

Phase II Feasibility and Biomarker Study of Neoadjuvant Trastuzumab and Pertuzumab With Chemoradiotherapy for Resectable Human Epidermal Growth Factor Receptor 2-Positive Esophageal Adenocarcinoma:TRAP Study

PURPOSE: Approximately 15% to 43% of esophageal adenocarcinomas (EACs) are human epidermal growth factor receptor 2 (HER2) positive. Because dual-agent HER2 blockade demonstrated a survival benefit in breast cancer, we conducted a phase II feasibility study of trastuzumab and pertuzumab added to neoadjuvant chemoradiotherapy (nCRT) in patients with EAC. PATIENTS AND METHODS: Patients with resectable HER2-positive EAC received standard nCRT with carboplatin and paclitaxel and 41.4 Gy of radiotherapy, with 4 mg/kg of trastuzumab on day 1, 2 mg/kg per week during weeks 2 to 6, and 6 mg/kg per week during weeks 7, 10, and 13 and 840 mg of pertuzumab every 3 weeks. The primary end point was feasibility, defined as ≥ 80% completion of treatment with both trastuzumab and pertuzumab. An exploratory comparison of survival with a propensity score-matched cohort receiving standard nCRT was performed, as were exploratory pharmacokinetic and biomarker analyses. RESULTS: Of the 40 enrolled patients (78% men; median age, 63 years), 33 (83%) completed treatment with trastuzumab and pertuzumab. No unexpected safety events were observed. R0 resection was achieved in all patients undergoing surgery, with pathologic complete response in 13 patients (34%). Three-year progression-free and overall survival (OS) were 57% and 71%, respectively (median follow-up, 32.1 months). Compared with the propensity score-matched cohort, a significantly longer OS was observed with HER2 blockade (hazard ratio, 0.58; 95% CI, 0.34 to 0.97). Results of pharmacokinetic analysis and activity on [18F]fluorodeoxyglucose positron emission tomography scans did not correlate with survival or pathologic response. Patients with HER2 3+ overexpression or growth factor receptor-bound protein 7 (Grb7) -positive tumors at baseline demonstrated significantly better survival (P = .007) or treatment response (P = .016), respectively. CONCLUSION: Addition of trastuzumab and pertuzumab to nCRT in patients with HER2-positive EAC is feasible and demonstrates potentially promising activity compared with historical controls. HER2 3+ overexpression and Grb7 positivity are potentially predictive for survival and treatment response, respectively

A new population pharmacokinetic model for recombinant factor IX‐Fc fusion concentrate including young children with haemophilia B

Aims: Recombinant factor IX Fc fusion protein (rFIX‐Fc) is an extended half‐life factor concentrate administered to haemophilia B patients. So far, a population pharmacokinetic (PK) model has only been published for patients aged ≥12 years. The aim was to externally evaluate the predictive performance of the published rFIX‐Fc population PK model for patients of all ages and develop a model that describes rFIX‐Fc PK using real‐world data. Methods: We collected prospective and retrospective data from patients with haemophilia B treated with rFIX‐Fc and included in the OPTI‐CLOT TARGET study (NTR7523) or United Kindom (UK)‐EHL Outcomes Registry (NCT02938156). Predictive performance was assessed by comparing predicted with observed FIX activity levels. A new population PK model was constructed using nonlinear mixed‐effects modelling. Results: Real‐world data were obtained from 37 patients (median age: 16 years, range 2–71) of whom 14 were aged <12 years. Observed FIX activity levels were significantly higher than levels predicted using the published model, with a median prediction error of −48.8%. The new model showed a lower median prediction error (3.4%) and better described rFIX‐Fc PK, especially for children aged <12 years. In the new model, an increase in age was correlated with a decrease in clearance (P < .01). Conclusions: The published population PK model significantly underpredicted FIX activity levels. The new model better describes rFIX‐Fc PK, especially for children aged <12 years. This study underlines the necessity to strive for representative population PK models, thereby avoiding extrapolation outside the studied population

Pharmacokinetics and pharmacodynamics of medication in asphyxiated newborns during controlled hypothermia. The PharmaCool multicenter study

<p>Abstract</p> <p>Background</p> <p>In the Netherlands, perinatal asphyxia (severe perinatal oxygen shortage) necessitating newborn resuscitation occurs in at least 200 of the 180–185.000 newly born infants per year. International randomized controlled trials have demonstrated an improved neurological outcome with therapeutic hypothermia. During hypothermia neonates receive sedative, analgesic, anti-epileptic and antibiotic drugs. So far little information is available how the pharmacokinetics (PK) and pharmacodynamics (PD) of these drugs are influenced by post resuscitation multi organ failure and the metabolic effects of the cooling treatment itself. As a result, evidence based dosing guidelines are lacking. This multicenter observational cohort study was designed to answer the question how hypothermia influences the distribution, metabolism and elimination of commonly used drugs in neonatal intensive care.</p> <p>Methods/Design</p> <p>Multicenter cohort study. All term neonates treated with hypothermia for Hypoxic Ischemic Encephalopathy (HIE) resulting from perinatal asphyxia in all ten Dutch Neonatal Intensive Care Units (NICUs) will be eligible for this study. During hypothermia and rewarming blood samples will be taken from indwelling catheters to investigate blood concentrations of several antibiotics, analgesics, sedatives and anti-epileptic drugs. For each individual drug the population PK will be characterized using Nonlinear Mixed Effects Modelling (NONMEM). It will be investigated how clearance and volume of distribution are influenced by hypothermia also taking maturation of neonate into account. Similarly, integrated PK-PD models will be developed relating the time course of drug concentration to pharmacodynamic parameters such as successful seizure treatment; pain assessment and infection clearance.</p> <p>Discussion</p> <p>On basis of the derived population PK-PD models dosing guidelines will be developed for the application of drugs during neonatal hypothermia treatment. The results of this study will lead to an evidence based drug treatment of hypothermic neonatal patients. Results will be published in a national web based evidence based paediatric formulary, peer reviewed journals and international paediatric drug references.</p> <p>Trial registration</p> <p>NTR2529.</p

Pil op maat

Binnen de oncologie, de kindergeneeskunde en de transplantatiegeneeskunde ontvangen patiënten vaak geneesmiddelen die balanceren tussen effectiviteit en toxiciteit. De effectiviteit en veiligheid van een medicijnbehandeling bij deze patiënten kan verbeterd worden door onderzoek te doen naar de farmacokinetiek (de relatie tussen dosis en bloedconcentratie) en farmacodynamiek (de relatie tussen concentratie en effect) van deze middelen. Met behulp van nieuwe, geavanceerde analysetechnieken wordt onderzocht of er specifieke demografische, genetische en/of pathologische factoren zijn die verschillen in geneesmiddelkinetiek en -dynamiek tussen patiënten kunnen verklaren. De geïdentificeerde factoren worden vervolgens gebruikt om de behandeling met medicijnen te individualiseren en te optimaliseren: een pil op maat