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Background: Pexidartinib is effective in patients with tenosynovial giant cell tumor (TGCT) for whom surgery is not feasible. Durability of response after discontinuation of pexidartinib and the safety and efficacy of restarting pexidartinib have not been previously recorded. This phase 4 study was designed to mimic the real-world experience with pexidartinib to evaluate the effects of discontinuation of and retreatment with pexidartinib in patients with TGCT who previously benefited from the drug., Methods: This was a global, multicenter, phase 4 study that enrolled patients with TGCT who were experiencing clinical benefit from pexidartinib in one of four prior phase 1 or phase 3 studies investigating pexidartinib in the disease. Patients could choose to continue pexidartinib at the same dose (the treatment-continuation cohort) or discontinue treatment with the option to restart pexidartinib (the treatment-free/retreatment cohort). Tumor progression determined by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, patient-reported outcomes (the Patient-Reported Outcomes Measurement Information System-Physical Function [PROMIS-PF] questionnaire and the EuroQol 5-dimension, 5-level [EQ-5D-5L] visual analog scale), and safety were assessed every 3 months. The primary end point was the proportion of patients in the treatment-free/retreatment cohort who remained treatment-free at month 12 and 24; this did not depend on disease progression., Results: Thirty-two patients were enrolled: 21 chose to enter the treatment-continuation cohort, and 11 entered the treatment-free/retreatment cohort. During the treatment-free period, six of 11 (54.5%) patients in the treatment-free/retreatment cohort had progressive disease (PD) according to RECIST, version 1.1, whereas no patient in the treatment-continuation cohort had disease progression. Over the 24-month study, three of 11 (27.3%) patients in the treatment-free/retreatment cohort restarted treatment because of RECIST version 1.1 PD, symptomatic progression, or both (n = 1 each). The probability of remaining treatment-free in the treatment-free/retreatment cohort was 73% (95% confidence interval, 37%-90%). In the treatment-free/retreatment cohort, the median progression-free survival of the treatment-free period was 22.8 months (95% confidence interval, 1.6 months to not estimable). By 6 months of retreatment, all retreated patients achieved new disease stabilization with no new safety concerns; two patients had clinically significant improvements in PROMIS-PF and EQ-5D-5L visual analog scale scores. The mean PROMIS-PF and EQ-5D-5L scores remained stable throughout the study. There was no hepatotoxicity and no new safety signal in either cohort., Conclusions: In this small phase 4 study designed to evaluate outcomes in patients who stopped and restarted pexidartinib, 54.5% of patients who discontinued pexidartinib showed PD, with a median progression-free survival of 22.8 months. Each of the three patients who restarted pexidartinib stopped progressing, and some reported a new gain in physical function. No PD was detected in patients who remained on treatment, and the safety profile did not indicate long-term hepatotoxicity or any new safety concerns., Plain Language Summary: Pexidartinib is a medication for people with tenosynovial giant cell tumor (TGCT) for whom surgery is not recommended. This study examined what happens when patients stop taking pexidartinib (after it has helped them) to see whether it is safe and effective to restart if needed. Thirty-two patients were followed for 2 years: 21 chose to continue pexidartinib and did not experience disease progression, while 11 chose to stop pexidartinib; 54.5% of them had disease progression within 2 years. Three patients who stopped pexidartinib restarted treatment after their tumor size increased or their symptoms worsened. Restarting pexidartinib was safe and effective in these patients., (© 2024 The Author(s). Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Edoxaban is an orally active inhibitor of activated factor X (FXa). Population pharmacokinetic (PK) and pharmacodynamic (PD) analyses were performed to characterize the PK and PK-PD relationships of edoxaban in pediatric patients to identify the covariates that may contribute to inter-subject variability in PK and PD of edoxaban in pediatric patients, and to compare the PK and PD data between pediatric and adult patients. The pediatric PK of edoxaban was best described by a two-compartment model with transit compartments, first-order oral absorption, and linear elimination. The estimated glomerular filtration rate (eGFR), body weight, and post-menstrual age were the significant covariates explaining variability in edoxaban PK among pediatric patients. A function based on renal maturation was applied to edoxaban clearance. The clearance for a 70 kg patient with an eGFR of 110 mL/min/1.73 m 2 was estimated to be 42.9 L/h (CV ~ 31.8%). PK simulation showed that exposures across five pediatric age groups were comparable to that in adult patients receiving 60 mg once daily dose. The PK-PD relationship for anti-factor Xa was best fit with an E max (8.65 IU/mL) model with an EC 50 of 631 ng/mL. The PK-PD relationships for activated partial thromboplastin time and prothrombin time were best fit with linear models (slopes of 0.0467, and 0.0415 s mL/ng, respectively). In addition, due to the small number of efficacy and safety events, an exploratory analysis did not detect a correlation between efficacy events (recurrent venous thromboembolism) or safety events (clinically relevant bleeding) and edoxaban exposure., (© 2024 The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

The pediatric clinical development programs of the direct oral anticoagulants (DOACs) edoxaban, rivaroxaban, and dabigatran have recently been completed, with apixaban close to the finish line. One common pharmacokinetic (PK) characteristic of these four DOACs is that renal excretion contributes 27% or more in their elimination, resulting in age-dependent drug clearance in both pediatric and adult subjects. Several lessons have been learned from adult exposure matching and pediatric dose selection for DOACs. The main goal of this tutorial is to provide an informed perspective on pediatric dose selection for renally excreted drugs, using these four DOACs as case examples. This tutorial is organized into seven steps: (1) consideration of age-related differences in disease and response to treatment; (2) consideration of age-related differences in drug absorption, distribution, metabolism, and excretion; (3) selection of the reference adult population and exposure for pediatric exposure matching; (4) prediction of pediatric clearance and pediatric dose selection based on data from young adults; (5) conduct and design of efficient pediatric PK and pharmacodynamic (PD) studies that inform dose selection; (6) assessment of exposure matching and dose adjustment using population PK simulation; (7) evaluation of the need for dose adjustment in pediatric sub-populations., (© 2024 The Author(s). Clinical Pharmacology & Therapeutics © 2024 American Society for Clinical Pharmacology and Therapeutics.)

Stan is a powerful probabilistic programming language designed mainly for Bayesian data analysis. Torsten is a collection of Stan functions that handles the events (e.g., dosing events) and solves the ODE systems that are frequently present in pharmacometric models. To perform a Bayesian data analysis, most models in pharmacometrics require Markov Chain Monte Carlo (MCMC) methods to sample from the posterior distribution. However, MCMC is computationally expensive and can be time-consuming, enough so that people will often forgo Bayesian methods for a more traditional approach. This paper shows how to speed up the sampling process in Stan by within-chain parallelization through both multi-threading using Stan's reduce_sum() function and multi-processing using Torsten's group ODE solver. Both methods show substantial reductions in the time necessary to sufficiently sample from the posterior distribution compared with a basic approach with no within-chain parallelization., (© 2024 The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Physiologically-based pharmacokinetic (PBPK) modeling offers a viable approach to predict induction drug-drug interactions (DDIs) with the potential to streamline or reduce clinical trial burden if predictions can be made with sufficient confidence. In the current work, the ability to predict the effect of rifampin, a well-characterized strong CYP3A4 inducer, on 20 CYP3A probes with publicly available PBPK models (often developed using a workflow with optimization following a strong inhibitor DDI study to gain confidence in fraction metabolized by CYP3A4, f m,CYP3A4 , and fraction available after intestinal metabolism, Fg), was assessed. Substrates with a range of f m,CYP3A4 (0.086-1.0), Fg (0.11-1.0) and hepatic availability (0.09-0.96) were included. Predictions were most often accurate for compounds that are not P-gp substrates or that are P-gp substrates but that have high permeability. Case studies for three challenging DDI predictions (i.e., for eliglustat, tofacitinib, and ribociclib) are presented. Along with parameter sensitivity analysis to understand key parameters impacting DDI simulations, alternative model structures should be considered, for example, a mechanistic absorption model instead of a first-order absorption model might be more appropriate for a P-gp substrate with low permeability. Any mechanisms pertinent to the CYP3A substrate that rifampin might impact (e.g., induction of other enzymes or P-gp) should be considered for inclusion in the model. PBPK modeling was shown to be an effective tool to predict induction DDIs with rifampin for CYP3A substrates with limited mechanistic complications, increasing confidence in the rifampin model. While this analysis focused on rifampin, the learnings may apply to other inducers., (© 2024 The Author(s). Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Valemetostat is an oral inhibitor of enhancer of zeste homolog (EZH) 2 and EZH1 approved in Japan for the treatment of adult T-cell leukemia/lymphoma (ATLL). To support the approved daily dose of 200 mg and inform dose adjustments in patients with ATLL, Bayesian exposure-response analyses were conducted using data from two clinical trials. The analyses included two efficacy endpoints, overall response by central and investigator assessments in patients with ATLL (n = 38, 150-200 mg), and six safety endpoints in patients with non-Hodgkin lymphoma (n = 102, 150-300 mg), which included grade ≥3 laboratory values for anemia, absolute neutrophil count decreased, and platelet count decreased; any grade ≥3 treatment-emergent adverse event (TEAE); and dose reductions and dose interruptions due to TEAEs. A slightly positive relationship was observed between unbound exposure and efficacy endpoints. A steeper relationship was observed in safety endpoints, compared with efficacy. Candidate covariate effects, except intercepts of the baseline laboratory values, were regularized via spike and slab priors in a Bayesian framework; only the laboratory values for corresponding hematologic TEAEs were shown to be of substantial impact. The target exposure range was established by defining a modified region of practical equivalence (184-887 ng·h/mL), which was expected to provide satisfactory efficacy and acceptable safety within the range of available exposure data. The simulated exposure range considering inter-individual variability showed that 200 mg could reach target exposure in the overall population and across subpopulations of interest, supporting the use of valemetostat 200 mg in patients with ATLL., (© 2024 The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Valemetostat is an EZH2/1 inhibitor that has been approved in Japan for the treatment of patients with relapsed/refractory adult T-cell leukemia/lymphoma, based mainly on results from a single-arm phase II trial. It is currently under investigation worldwide for the treatment of other non-Hodgkin lymphomas (NHLs), including peripheral T-cell lymphoma, and for solid tumors. Semi-mechanistic population pharmacokinetic modeling of total and unbound valemetostat and an analysis of the platelet time course during treatment with valemetostat were conducted using data from five clinical trials (two in patients with NHL and three in healthy volunteers). Pharmacokinetic data, including 3162 total/1871 unbound valemetostat observations from 102 patients and 72 healthy volunteers, were described by a three-compartment model with sequential zero-/first-order absorption and saturable binding in the central compartment. Alpha-1-acid glycoprotein (AAG) was the most influential covariate for total valemetostat exposure, yet had little impact on unbound exposure, meaning no dose adjustment was warranted based on AAG levels. The longitudinal platelet data from 101 patients (2313 observations) were adequately described by a modified Friberg model with two proliferation compartments, which characterized unique spontaneous recovery of platelet counts without dose modifications. A model-based simulation quantitatively assessed the proposed dose-adjustment guidance in case of platelet count decreased by comparing the probability of treatment discontinuation due to platelet count decreased with or without the dose adjustment. In summary, the models described observed total and unbound valemetostat concentrations and a unique time course of platelets during treatment, which can justify the clinical dose and provide dose-adjustment guidance., (© 2024 The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Purpose: There has been rapid growth in the variety and number of real-world data (RWD) sources, as well as the number of regulatory documents that provide guidance for assessing the suitability of RWD sources for pharmacoepidemiology studies. This study aims to assess differences in RWD guidance and variability in current practice for identifying and assessing RWD for studies with regulatory purpose., Methods: Key criteria for feasibility assessment were mapped against relevant regulatory guidance documents across US, EU, and Asia-Pacific regions. An online survey was designed and deployed to International Society for Pharmacoepidemiology members to understand current practice. Findings were summarized and used to inform key considerations and recommendations., Results: Eleven RWD guidance documents were identified and mapped against 14 RWD assessment criteria. Variability was seen across these documents in guidance for these criteria. Between December 2022 and January 2023, 37 survey respondents reported having used RWD for post-marketing commitments (34, 92%) and/or background epidemiology (28, 76%). RWD were mostly identified through literature (33, 89%) and data landscaping (26, 70%); guidance documents referenced included: Food and Drug Administration (20, 54%), European Network for Centres for Pharmacoepidemiology and Pharmacovigilance (17, 46%), European Medical Agency (16, 43%), and Structured Process to Identify Fit-For-Purpose Data (11, 30%). Challenges for conducting feasibility assessments included RWD accessibility, ability to complete validation, and RWD provider responsiveness., Conclusions: Existing guidelines are used extensively by researchers, but key criteria for RWD identification and feasibility assessment are not reflected consistently and challenges remain. Recommendations have been made reflecting study findings., (© 2024 The Author(s). Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.)

This was an open-label, single-dose, phase I study to characterize the pharmacokinetics (PKs), pharmacodynamics (PDs), and safety of edoxaban in pediatric subjects from birth to 18 years at risk for venous thromboembolism (VTE). Children requiring anticoagulant therapy were enrolled into 5 age cohorts (0 to < 6 months (N = 12), 0.5 to < 2 years (N = 13), 2 to < 6 years (N = 13), 6 to < 12 years (N = 13), and 12 to < 18 years (N = 15)) receiving tablet or oral suspension of edoxaban at doses expected to be equivalent to 30 or 60 mg once daily (q.d.) in adult subjects with VTE. Sixty-six pediatric subjects were enrolled and completed the study. Edoxaban plasma concentration peaked between 1 and 3 hours and declined rapidly until 4-8 hours. The range of mean total apparent clearance across 5 age cohorts at low and high doses was 0.47 to 1.11 L/h/kg. The ranges of mean volume of central compartment and apparent peripheral volume were 2.31 to 3.59 L/kg and 1.92 to 4.14 L/kg, respectively. Across all age groups, the estimated median exposures were within the 0.5- to 1.5-fold of the median area under the plasma drug concentration-time curve (AUC) in adult subjects receiving corresponding doses (30 mg q.d. for low dose and 60 mg q.d. for high dose). In all age groups, PD parameters (prothrombin time, activated partial thromboplastin time, and anti-Factor Xa activity) showed a linear PK-PD relationship and were in line with previous adult data. The results support further evaluation of the pediatric doses in larger pivotal trials., (© 2024 Daiichi Sankyo Inc. Clinical Pharmacology & Therapeutics © 2024 American Society for Clinical Pharmacology and Therapeutics.)

The landscape of oncology drug development has witnessed remarkable advancements over the last few decades, significantly improving clinical outcomes and quality of life for patients with cancer. Project Optimus, introduced by the U.S. Food and Drug Administration, stands as a groundbreaking endeavor to reform dose selection of oncology drugs, presenting both opportunities and challenges for the field. To address complex dose optimization challenges, an Oncology Dose Optimization IQ Working Group was created to characterize current practices, provide recommendations for improvement, develop a clinical toolkit, and engage Health Authorities. Historically, dose selection for cytotoxic chemotherapeutics has focused on the maximum tolerated dose, a paradigm that is less relevant for targeted therapies and new treatment modalities. A survey conducted by this group gathered insights from member companies regarding industry practices in oncology dose optimization. Given oncology drug development is a complex effort with multidimensional optimization and high failure rates due to lack of clinically relevant efficacy, this Working Group advocates for a case-by-case approach to inform the timing, specific quantitative targets, and strategies for dose optimization, depending on factors such as disease characteristics, patient population, mechanism of action, including associated resistance mechanisms, and therapeutic index. This white paper highlights the evolving nature of oncology dose optimization, the impact of Project Optimus, and the need for a tailored and evidence-based approach to optimize oncology drug dosing regimens effectively., (© 2024 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Toll-like receptor (TLR)7 is a pattern recognition receptor that critically contributes to the pathogenesis of systemic lupus erythematosus (SLE). DS-7011a is an anti-TLR7 monoclonal antibody that prevents TLR7 from signaling. The aim of this first-in-human, double-blind, randomized, and placebo-controlled study was to evaluate the safety, pharmacokinetics, immunogenicity, and pharmacodynamics of single ascending intravenous (IV) and subcutaneous (SC) doses of DS-7011a in healthy subjects (HS) (NCT05203692). On day 1, 80 HS received DS-7011a or placebo 6:2 in 10 cohorts (7 treated IV and 3 SC) of 8 each and were followed for 8 weeks until day 57. Safety was evaluated by recording treatment-emergent adverse events (TEAEs), pharmacokinetics by measuring plasma DS-7011a, immunogenicity by measuring plasma anti-drug antibodies (ADAs), and pharmacodynamics by evaluating the suppression of interleukin-6 production ex vivo in whole blood. DS-7011a was safe and well tolerated across all cohorts. TEAEs were mostly mild in severity and not drug-related. DS-7011a exposure increased with the dose but was not dose proportional, as the elimination of lower doses was accelerated by target-mediated drug disposition. Terminal half-life was about 15-17 days and T max upon SC administration was about 5 days. DS-7011a induced ADAs in about half of HS but with no impact on clinical findings and pharmacokinetics. Pharmacodynamic (PD) response also increased with the dose and at the higher doses was of large extent (>90%), early onset, and lasting duration. DS-7011a showed favorable safety, pharmacokinetics, immunogenicity, and PD properties that support its development for the treatment of SLE., (© 2024, The American College of Clinical Pharmacology.)

Background: Vitamin D supplementation during pregnancy may help improve maternal and neonatal health outcomes (such as fewer preterm birth and low birthweight babies) and reduce the risk of adverse pregnancy outcomes (such as severe postpartum haemorrhage)., Objectives: To examine whether vitamin D supplementation alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve certain maternal and neonatal outcomes., Search Methods: We searched the Cochrane Pregnancy and Childbirth Trials Register (which includes results of comprehensive searches of CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, and relevant conference proceedings) (3 December 2022). We also searched the reference lists of retrieved studies., Selection Criteria: Randomised and quasi-randomised trials evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy in comparison to placebo or no intervention., Data Collection and Analysis: Two review authors independently i) assessed the eligibility of studies against the inclusion criteria, ii) assessed trustworthiness based on pre-defined criteria of scientific integrity, iii) extracted data from included studies, and iv) assessed the risk of bias of the included studies. We assessed the certainty of the evidence using the GRADE approach., Main Results: The previous version of this review included 30 studies; in this update, we have removed 20 of these studies to 'awaiting classification' following assessments of trustworthiness, one study has been excluded, and one new study included. This current review has a total of 10 included studies, 117 excluded studies, 34 studies in awaiting assessment, and seven ongoing studies. We used the GRADE approach to assess the certainty of the evidence. This removal of the studies resulted in evidence that was downgraded to low-certainty or very low-certainty due to study design limitations, inconsistency between studies, and imprecision. Supplementation with vitamin D compared to no intervention or a placebo A total of eight studies involving 2313 pregnant women were included in this comparison. We assessed four studies as having a low risk of bias for most domains and four studies as having high risk or unclear risk of bias for most domains. The evidence is very uncertain about the effect of supplementation with vitamin D during pregnancy compared to placebo or no intervention on pre-eclampsia (risk ratio (RR) 0.53, 95% confidence interval (CI) 0.21 to 1.33; 1 study, 165 women), gestational diabetes (RR 0.53, 95% CI 0.03 to 8.28; 1 study, 165 women), preterm birth (< 37 weeks) (RR 0.76, 95% CI 0.25 to 2.33; 3 studies, 1368 women), nephritic syndrome (RR 0.17, 95% CI 0.01 to 4.06; 1 study, 135 women), or hypercalcaemia (1 study; no cases reported). Supplementation with vitamin D during pregnancy may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome (RR 0.68, 95% CI 0.51 to 0.91; 1 study, 1134 women; low-certainty evidence) and may reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out (RR 0.69, 95% CI 0.44 to 1.08; 3 studies, 371 infants; low-certainty evidence). Supplementation with vitamin D + calcium compared to no intervention or a placebo One study involving 84 pregnant women was included in this comparison. Overall, this study was at moderate to high risk of bias. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported. The evidence is very uncertain about the effect of supplementation with vitamin D and calcium on preterm birth (RR not estimable; very low-certainty evidence) or for low birthweight (RR 1.45, 95% CI 0.14 to 14.94; very low-certainty evidence) compared to women who received placebo or no intervention. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) One study involving 1298 pregnant women was included in this comparison. We assessed this study as having a low risk of bias in all domains. Pre-eclampsia was not reported. The evidence is very uncertain about the effect of supplementation with vitamin D, calcium, and other vitamins and minerals during pregnancy compared to no vitamin D on gestational diabetes (RR 0.42, 95% CI 0.10 to 1.73; very low-certainty evidence), maternal adverse events (hypercalcaemia no events and hypercalciuria RR 0.25, 95% CI 0.02 to 3.97; very low-certainty evidence), preterm birth (RR 1.04, 95% CI 0.68 to 1.59; low-certainty evidence), or low birthweight (RR 1.12, 95% CI 0.82 to 1.51; low-certainty evidence)., Authors' Conclusions: This updated review using the trustworthy assessment tool removed 21 studies from the previous update and added one new study for a total of 10 included studies. In this setting, supplementation with vitamin D alone compared to no intervention or a placebo resulted in very uncertain evidence on pre-eclampsia, gestational diabetes, preterm birth, or nephritic syndrome. It may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome. It may also reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out. Supplementation with vitamin D and calcium versus placebo or no intervention resulted in very uncertain evidence on preterm birth and low birthweight. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported in the only study included in this comparison. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) resulted in very uncertain evidence on gestational diabetes and maternal adverse events (hypercalciuria) and uncertain evidence on preterm birth and low birthweight. Pre-eclampsia was not reported in the only study included in this comparison. All findings warrant further research. Additional rigorous, high-quality, and larger randomised trials are required to evaluate the effects of vitamin D supplementation in pregnancy, particularly in relation to the risk of maternal adverse events., (Copyright © 2024 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)

Microfiltration (MF) is an essential step during biopharmaceutical manufacturing. However, unexpected flux decay can occur. Although the flux decay profile and initial flux are important factors determining MF filterability, predicting them accurately is challenging, as the root cause of unexpected flux decay remains elusive. In this study, the methodology for developing a prediction model of flux decay profiles was established. First, the filtration profiles of different monodisperse polystyrene latex and silica beads of various sizes were evaluated. These results revealed that the size and surface electrostatic properties of the beads affect the flux decay profile. Taking the size and surface electrostatic properties of protein aggregates into account, we constructed a predictive model using model bead filtration profiles. We showed that this methodology was applicable to two different MF filters to predict the flux decay profile of therapeutic proteins. Because our proposed prediction model is based on normalized flux, the initial flux is required to predict the overall filtration profile. Then, we applied the Hagen-Poiseuille equation using sample viscosity values to estimate the initial flux. The developed prediction models can be used for effective MF scale-up assessment during the early stages of process development., (© 2024 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals LLC.)

The intent of this perspective is to share the recommendations of the International Consortium for Innovation and Quality in Pharmaceutical Development Metabolite Bioanalysis Working Group on the fit-for-purpose metabolite bioanalysis in support of drug development and registration. This report summarizes the considerations for the trigger, timing, and rigor of bioanalysis in the various assessments to address unique challenges due to metabolites, with respect to efficacy and safety, which may arise during drug development from investigational new drug (IND) enabling studies, and phase I, phase II, and phase III clinical trials to regulatory submission. The recommended approaches ensure that important drug metabolites are identified in a timely manner and properly characterized for efficient drug development., (© 2023 Novartis. AbbVie Inc. Incyte Corporation et al. Clinical Pharmacology & Therapeutics © 2023 American Society for Clinical Pharmacology and Therapeutics.)

Purpose: Real-world evidence (RWE) is increasingly used for medical regulatory decisions, yet concerns persist regarding its reproducibility and hence validity. This study addresses reproducibility challenges associated with diversity across real-world data sources (RWDS) repurposed for secondary use in pharmacoepidemiologic studies. Our aims were to identify, describe and characterize practices, recommendations and tools for collecting and reporting diversity across RWDSs, and explore how leveraging diversity could improve the quality of evidence., Methods: In a preliminary phase, keywords for a literature search and selection tool were designed using a set of documents considered to be key by the coauthors. Next, a systematic search was conducted up to December 2021. The resulting documents were screened based on titles and abstracts, then based on full texts using the selection tool. Selected documents were reviewed to extract information on topics related to collecting and reporting RWDS diversity. A content analysis of the topics identified explicit and latent themes., Results: Across the 91 selected documents, 12 topics were identified: 9 dimensions used to describe RWDS (organization accessing the data source, data originator, prompt, inclusion of population, content, data dictionary, time span, healthcare system and culture, and data quality), tools to summarize such dimensions, challenges, and opportunities arising from diversity. Thirty-six themes were identified within the dimensions. Opportunities arising from data diversity included multiple imputation and standardization., Conclusions: The dimensions identified across a large number of publications lay the foundation for formal guidance on reporting diversity of data sources to facilitate interpretation and enhance replicability and validity of RWE., (© 2024 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.)

Quizartinib is a potent, oral, second-generation, selective type II FMS-like receptor tyrosine kinase 3 (FLT3) inhibitor. It has shown improved overall survival in a randomized, multinational, Phase 3 (QuANTUM-First) study in patients with FLT3-internal tandem duplication (ITD)-positive newly diagnosed acute myeloid leukemia. We conducted 2 Phase 1b studies in Japan and China to evaluate the safety, pharmacokinetics, and efficacy of quizartinib in combination with standard induction and consolidation chemotherapy in patients with newly diagnosed acute myeloid leukemia. Quizartinib was started at a dose level of 20 mg/day and then escalated to 40 mg/day, the dose used in the Phase 3 study. Seven patients were enrolled according to the 3 + 3 dose-escalation method in each study, including 3 patients who were FLT3-ITD positive. No dose-limiting toxicities were observed at dose levels up to 40 mg/day in both studies. Grade 3 or higher, quizartinib-related, treatment-emergent adverse events included febrile neutropenia, hematologic toxicities, and infections. QT prolongation on electrocardiogram was observed in 5 patients. The pharmacokinetics of quizartinib and its metabolite AC886 were similar between the studies and consistent with previous findings in the United States. We confirmed the tolerability of Japanese and Chinese patients to the dose of quizartinib and chemotherapy regimens used in the QuANTUM-First study., (© 2024 Daiichi Sankyo Co., Ltd. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Background: The relationships between frailty and clinical outcomes in elderly Japanese patients with non-valvular atrial fibrillation (NVAF) after catheter ablation (CA) have not been established. We evaluated the frailty rate of patients undergoing CA for NVAF, examined whether CA for NVAF improves frailty, and analyzed the CA outcomes of patients with and without frailty., Methods: Elderly Japanese patients (≥65 years; mean age: 72.8 years) who participated in the real-world ablation therapy with anti-coagulants in management of atrial fibrillation registry and who responded to the frailty screening index survey were included ( n  = 213). Frailty and AF recurrence were assessed preoperatively and at 3 and 6 months after CA., Results: Twenty-six patients (12.8%) were frail, 109 (53.7%) were pre-frail, and 68 (33.5%) were robust. Cardiovascular (frailty: 0.5%/person-year; pre-frailty: 0.1%/person-year; robust: 0.1%/person-year) and cardiac (frailty: 0.5%/person-year; pre-frailty: 0.1%/person-year; robust: 0.1%/person-year) events, as well as major bleeding (frailty: 0.3%/person-year; pre-frailty: 0.1%/person-year; robust: 0.1%/person-year), were numerically more frequent in the frailty group. No deaths from cardiovascular or stroke/systemic thromboembolic events occurred. A large proportion of patients did not experience 3-month (frailty: 96.2%; pre-frailty: 96.3%; robust: 88.2%) or 6-month (frailty: 88.5%; pre-frailty: 91.7%; robust: 86.8%) AF recurrence after CA. Weight loss, walking speed, and fatigue improved in the frailty and pre-frailty groups after CA., Conclusion: Japanese patients aged ≥65 years with frailty or pre-frailty had improved frailty screening index components, such as weight loss, walking speed and fatigue, after CA. Therefore, elderly patients with frailty or pre-frailty may benefit from CA for NVAF., Competing Interests: KS has received honoraria from Boehringer Ingelheim, Daiichi Sankyo, Abbott, Medtronic, and Johnson & Johnson. KK has received honoraria from Daiichi Sankyo, Boehringer Ingelheim, Fukuda Denshi, Nihon Kohden, Toray, and Japan Lifeline. KU has received honoraria from Japan Lifeline. T Kurita has received honoraria from Bayer, Boehringer Ingelheim, Daiichi Sankyo, Bristol‐Myers Squibb, Abbott, Medtronic, and Johnson & Johnson. AN has received honoraria from Boehringer Ingelheim, Daiichi Sankyo, Bristol Myers Squibb, Abbott, and Johnson & Johnson, and endowments from Medtronic and DVX. IM has received honoraria from Daiichi Sankyo and Abbott. FM has received honoraria from Medtronic, Abbott, and Biotronik. RK has received grant support from Boston Scientific, Abbott, Bayer, and Japan Lifeline. T Kimura and AT are employees of Daiichi Sankyo. MG has received honoraria from Pfizer, Ferring Pharma, Daiichi Sankyo, Merck Biopharma, and Novartis. KA has received honoraria from Boston Scientific, Japan Lifeline, Nihon Kohden, Biotronik, Toray Industries, ASTEC, Abbott, Boehringer Ingelheim, and Century Medical., (© 2024 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of Japanese Heart Rhythm Society.)

Pexidartinib is a systemic treatment for patients with tenosynovial giant cell tumor not amenable to surgery. Oral absorption of pexidartinib is affected by food; administration with a high-fat meal (HFM) or low-fat meal (LFM) increases absorption by approximately 100% and approximately 60%, respectively, compared with the fasted state. Pexidartinib is currently dosed 250 mg orally twice daily with an LFM (approximately 11-14 g of total fat). We developed a physiologically based pharmacokinetic model to determine the impact on drug exposure of dose timing with respect to meals, meal type, and caloric content. A 15%-16% increase in plasma exposure was predicted when consuming an HFM 1 hour after dosing with an LFM, but almost no effect on pharmacokinetics was predicted when an HFM was consumed 3 hours or more before or after pexidartinib dosing with an LFM. Exposure was not significantly affected when pexidartinib was taken with a 500-kcal LFM over the range of fat (approximately 11-14 g of total fat; 20%-25% calories from fat) for an LFM. These findings on timing of pexidartinib dose with respect to meals should be considered by patients and physicians to reduce the potential for side effects., (© 2024 Daiichi Sankyo Co. Ltd and Simulation Plus, Inc. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Recent breakthroughs in artificial intelligence (AI) and machine learning (ML) have ushered in a new era of possibilities across various scientific domains. One area where these advancements hold significant promise is model-informed drug discovery and development (MID3). To foster a wider adoption and acceptance of these advanced algorithms, the Innovation and Quality (IQ) Consortium initiated the AI/ML working group in 2021 with the aim of promoting their acceptance among the broader scientific community as well as by regulatory agencies. By drawing insights from workshops organized by the working group and attended by key stakeholders across the biopharma industry, academia, and regulatory agencies, this white paper provides a perspective from the IQ Consortium. The range of applications covered in this white paper encompass the following thematic topics: (i) AI/ML-enabled Analytics for Pharmacometrics and Quantitative Systems Pharmacology (QSP) Workflows; (ii) Explainable Artificial Intelligence and its Applications in Disease Progression Modeling; (iii) Natural Language Processing (NLP) in Quantitative Pharmacology Modeling; and (iv) AI/ML Utilization in Drug Discovery. Additionally, the paper offers a set of best practices to ensure an effective and responsible use of AI, including considering the context of use, explainability and generalizability of models, and having human-in-the-loop. We believe that embracing the transformative power of AI in quantitative modeling while adopting a set of good practices can unlock new opportunities for innovation, increase efficiency, and ultimately bring benefits to patients., (© 2023 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Valemetostat is an oral, selective inhibitor of enhancer of zeste homolog-2 (EZH2) and EZH1. In a first-in-human phase-1 trial, valemetostat capsules were well tolerated and clinically active in patients with relapsed/refractory non-Hodgkin lymphoma. Subsequently, a film-coated tablet formulation was developed for future clinical trials and commercialization. We report outcomes from 2 phase 1 trials in healthy Japanese participants, assessing the safety, tolerability, and pharmacokinetics (PK) of valemetostat tablets at single ascending doses (50, 100, and 200-mg), the relative bioavailability between capsules and tablets, and the effect of food (high-fat or low-fat meals) on the PK of valemetostat tablets. In the ascending-dose study, valemetostat maximum plasma concentration (C max ) and area under the concentration-time curve (AUC) increased dose-proportionally. Valemetostat plasma PK parameters were similar between the capsule and tablet formulations following a single 200-mg dose. Administration of valemetostat, 200 mg after a meal, was associated with 50%-60% lower C max , 30%-50% lower AUC, and a median T max delay of 2.5-3 hours relative to fasted administration. Valemetostat was well tolerated in healthy subjects; treatment-emergent adverse events were mild (grade 1) in severity. Based on these trials, the tablet formulation of valemetostat is suitable for use in subsequent clinical trials and should be administered under fasted conditions to avoid a negative food effect., (© 2023 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Imipenem/cilastatin/relebactam is approved for the treatment of serious gram-negative bacterial infections in adults. This study assessed the pharmacokinetics (PK), safety, and tolerability of a single dose of imipenem/cilastatin/relebactam (with a fixed 2:1 ratio of imipenem/cilastatin to relebactam, and with a maximum dose of 15 mg/kg imipenem and 15 mg/kg cilastatin [≤500 mg imipenem and ≤500 mg cilastatin] and 7.5 mg/kg relebactam [≤250 mg relebactam]) in children with confirmed/suspected gram-negative bacterial infections receiving standard-of-care antibacterial therapy. In this phase 1, noncomparative study (ClinicalTrials.gov identifier, NCT03230916), PK parameters from 46 children were analyzed using both population modeling and noncompartmental analysis. The PK/pharmacodynamic (PD) target for imipenem was percent time of the dosing interval that unbound plasma concentration exceeded the minimum inhibitory concentration (%fT>MIC) of ≥30% (MIC = 2 mcg/mL). For relebactam, the PK/PD target was a free drug area under the plasma concentration-time curve (AUC) normalized to MIC (at 2 mcg/mL) of ≥8.0 (equivalent to an AUC from time zero extrapolated to infinity of ≥20.52 mcg·h/mL). Safety was assessed up to 14 days after drug infusion. For imipenem, the ranges for the geometric mean %fT>MIC and maximum concentration (C max ) across age cohorts were 56.5%-93.7% and 32.2-38.2 mcg/mL, respectively. For relebactam, the ranges of the geometric mean C max and AUC from 0 to 6 hours across age cohorts were 16.9-21.3 mcg/mL and 26.1-55.3 mcg·h/mL, respectively. In total, 8/46 (17%) children experienced ≥1 adverse events (AEs) and 2/46 (4%) children experienced nonserious AEs that were deemed drug related by the investigator. Imipenem and relebactam exceeded plasma PK/PD targets; single doses of imipenem/cilastatin/relebactam were well tolerated with no significant safety concerns identified. These results informed imipenem/cilastatin/relebactam dose selection for further pediatric clinical evaluation., (© 2023 The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Cell culture scale-up is a challenging task due to the simultaneous change of multiple hydrodynamic process characteristics and their different dependencies on the bioreactor size as well as variation in the requirements of individual cell lines. Conventionally, the volumetric power input is the most common parameter to select the impeller speed for scale-up, however, it is well reported that this approach fails when there are huge differences in bioreactor scales. In this study, different scale-up criteria are evaluated. At first, different hydrodynamic characteristics are assessed using computational fluid dynamics data for four single-use bioreactors, the Mobius® CellReady 3 L, the Xcellerex™ XDR-10, the Xcellerex™ XDR-200, and the Xcellerex™ XDR-2000. On the basis of this numerical data, several potential scale-up criteria such as volumetric power input, impeller tip speed, mixing time, maximum hydrodynamic stress, and average strain rate in the impeller zone are evaluated. Out of all these criteria, the latter is found to be most appropriate, and the successful scale-up from 3 to 10 L bioreactor and to 200 L bioreactor is confirmed with cell culture experiments using Chinese Hamster Ovary cell cultivation., (© 2023 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals LLC.)

This study evaluated the benefit/risk of trastuzumab deruxtecan (T-DXd) 6.4 mg/kg in patients with human epidermal growth factor receptor 2 (HER2)-positive gastric cancer using pharmacometrics. A population pharmacokinetic (PopPK) model was developed using data from patients with gastric cancer, breast cancer, or other tumors in T-DXd clinical trials, primarily conducted in Asia. Post hoc model-estimated pharmacokinetic metrics were used in exposure-efficacy (objective response rates, ORRs) and exposure-safety analyses. The PopPK analysis included 808 patients (217 with gastric cancer, 512 with breast cancer, and 79 with other cancers). In gastric cancer, the T-DXd 6.4 mg/kg steady-state exposure metrics were lower compared with 6.4 mg/kg in breast cancer, but were similar to 5.4 mg/kg in breast cancer. Tumor type was selected as a significant covariate on T-DXd clearance. In exposure-efficacy analysis among 160 patients with gastric cancer, the T-DXd steady-state minimum concentration was associated with a confirmed ORR in univariate logistic regression analysis (P = .023). The model-predicted confirmed ORRs in gastric cancer were 36.0% (90%CI 29.3% to 43.7%) with 5.4 mg/kg and 40.0% (90%CI 33.1% to 47.6%) with 6.4 mg/kg. Among 808 patients in the exposure-safety analyses, the model-predicted estimates for the rates of any-grade interstitial lung disease (ILD) over a period of 180 days were 10.2% (90%CI 8.7% to 12.8%) with 6.4 mg/kg in gastric cancer and 9.7% (90%CI 8.2% to 11.8%) with 5.4 mg/kg in breast cancer. In gastric cancer, the efficacy of T-DXd was higher at 6.4 mg/kg than at 5.4 mg/kg. Exposure and ILD rates were comparable between 6.4 mg/kg in gastric cancer and 5.4 mg/kg in breast cancer. This study identified T-DXd 6.4 mg/kg as the recommended dose in HER2-positive gastric cancer., (© 2023 The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

This study bridged pharmacokinetic, efficacy, and safety clinical trial data from Japan to a Western population using real-world evidence (RWE) to investigate the antibody-drug conjugate trastuzumab deruxtecan (T-DXd) in the treatment of human epidermal growth factor receptor 2 (HER2)-positive advanced gastric cancer. Using population pharmacokinetic and exposure-response (efficacy/safety) models, exposure-efficacy data from 117 patients and exposure-safety data from 158 patients in Japan who received T-DXd 6.4 mg/kg as second-line or later treatment were bridged to RWE including covariate information from 25 Western patients with HER2-positive gastric cancer who received second-line or later T-DXd treatment. Pharmacokinetic simulations indicated that intact T-DXd and released drug (DXd) steady-state exposures were comparable between Western patients and patients from Japan; the Western/Japan ratio of exposure medians ranged from 0.82 (T-DXd steady-state minimum concentration) to 1.18 (DXd steady-state maximum concentration). Exposure-efficacy simulations estimated a confirmed objective response rate of 28.6% (90% confidence interval, 20.8-38.4) in real-world Western patients versus 40.1% (90% confidence interval, 33.5-47.0) in patients from Japan, possibly because of checkpoint inhibitor use in 4% versus 30% of patients, respectively. Western patients had a higher estimated rate of serious adverse events than patients from Japan (42.2% vs 34.6%); however, the rate of interstitial lung disease was lower (less than 10%) in Western patients. Overall, T-DXd was predicted to have meaningful clinical activity and a manageable safety profile in Western patients with HER2-positive gastric cancer. Using RWE, bridging analysis supported US approval of T-DXd 6.4 mg/kg in advanced gastric cancer before a clinical trial was completed in Western patients., (© 2023 The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

This single-center, randomized, open-label, single-dose, 2-group, 2-stage crossover trial evaluated the bioequivalence of 15 mg of mirogabalin as orally disintegrating tablets (ODTs) with conventional mirogabalin tablets in healthy Japanese men. The trial involved two studies: in Study 1, the ODT formulation was taken without water, and in Study 2, the ODT formulation was taken with water. The conventional tablet was taken with water in both studies. We investigated the pharmacokinetic parameters and bioequivalence of the 2 formulations, including the maximum plasma concentration and the area under the plasma concentration-time curve up to the last quantifiable time. The plasma concentrations of mirogabalin were determined by a validated liquid chromatography with tandem mass spectrometry method. A total of 72 participants were enrolled and completed the trial. The geometric least-squares mean ratios of maximum plasma concentration of the ODT formulation to the conventional formulation were within the prespecified bioequivalence range of 0.80-1.25 (Study 1, 0.995; Study 2, 1.009), as was the area under the plasma concentration-time curve up to the last quantifiable time (Study 1, 1.023; Study 2, 1.035). No serious adverse events were observed. In conclusion, mirogabalin 15-mg ODTs, either with or without water, were bioequivalent to conventional 15-mg tablets., (© 2023 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Trastuzumab deruxtecan (T-DXd, DS-8201a) is an antibody-drug conjugate, comprising an anti-HER2 antibody at a drug-to-antibody ratio of 7-8 with the topoisomerase I inhibitor DXd. In this study, the concentrations of antibody-conjugated DXd and total antibody were determined and observed to decrease over time following intravenous administration of T-DXd to monkeys. The drug-to-antibody ratio of T-DXd also decreased in a time-dependent manner, which reached approximately 2.5 in 21 days after administration. It was suggested that antibody-conjugated DXd of T-DXd was relatively stable in vivo compared with that of other reported antibody-drug conjugates., (© 2023 John Wiley & Sons Ltd.)

Background: Glycogen storage disease type Ia (GSDIa) is caused by biallelic pathogenic variants in the glucose-6-phosphatase gene (G6PC) and mainly characterized by hypoglycemia, hepatomegaly, and renal insufficiency. Although its symptoms are reportedly mild in patients carrying the G6PC c.648G>T variant, the predominant variant in Japanese patients, details remain unclear. Therefore, we examined continuous glucose monitoring (CGM) data and daily nutritional intake to clarify their associations in Japanese patients with GSDIa with G6PC c.648G>T., Methods: This cross-sectional study enrolled 32 patients across 10 hospitals. CGM was performed for 14 days, and nutritional intake was recorded using electronic diaries. Patients were divided according to genotype (homozygous/compound heterozygous) and age. The durations of biochemical hypoglycemia and corresponding nutritional intake were analyzed. Multiple regression analysis was performed to identify factors associated with the duration of biochemical hypoglycemia., Results: Data were analyzed for 30 patients. The mean daily duration of hypoglycemia (<4.0 mmol/L) in the homozygous group increased with age (2-11 years [N = 8]: 79.8 min; 12-18 years [5]: 84.8 min; ≥19 years [10]: 131.5 min). No severe hypoglycemic symptoms were recorded in the patients' diaries. The mean frequency of snack intake was approximately three times greater in patients aged 2-11 years (7.1 times/day) than in those aged 12-18 years (1.9 times/day) or ≥19 years (2.2 times/day). Total cholesterol and lactate were independently associated with the duration of biochemical hypoglycemia., Conclusion: Although nutritional therapy prevents severe hypoglycemia in patients with GSDIa with G6PC c.648G>T, patients often experience asymptomatic hypoglycemia., (© 2023 SSIEM.)

Aims: Cardiac functional and structural remodelling in patients with atrial fibrillation (AF) contributes to development of heart failure (HF) as their major cardiovascular comorbidity. Circulating biomarkers may reflect these cardiac alterations., Methods and Results: ENGAGE AF-TIMI 48 was a randomized trial of edoxaban versus warfarin in 21 105 patients with AF. We performed a nested biomarker study, analysing high-sensitivity troponin T (hsTnT, n = 8705), N-terminal pro-B-type natriuretic peptide (NT-proBNP, n = 8765), and growth differentiation factor-15 (GDF-15, n = 8705) at baseline and 12 months. Of the biomarker cohort, 5207 had a history of HF, among whom 3996 had known ejection fraction (EF): 926 with reduced EF (HFrEF; ≤40%), 1043 with mildly reduced EF (HFmrEF; 40-49%), and 2027 with preserved EF (HFpEF; ≥50%). Elevated baseline hsTnT, NT-proBNP, and GDF-15 were associated with higher risk of hospitalization for HF (HHF) or HF death overall and in subpopulations defined by HF history and EF (p < 0.001 for each). These associations of outcome with each biomarker were consistent regardless of a history of HF or EF (p-interaction >0.05 for each). Patients who had an increase in or had persistently elevated values in any of the three biomarkers over 12 months were at higher risk for HHF or HF death in the overall population (p < 0.001 for each biomarker and category)., Conclusion: Serial measurement of hsTnT, NT-proBNP, and GDF-15 revealed that higher baseline values, and increasing or persistently elevated values over 1 year are associated with higher risk of HF outcomes in patients with AF regardless of HF history or HF phenotype based on EF., Clinical Trial Registration: ClinicalTrials.gov unique identifier NCT00781391., (© 2023 European Society of Cardiology.)

Pexidartinib, an oral small molecule inhibitor of the colony-stimulating factor 1 receptor, is approved for treatment of adults with symptomatic tenosynovial giant cell tumor associated with severe morbidity or functional limitations and not amenable to improvement with surgery. The original dosing regimen is 400 mg of pexidartinib (2 × 200-mg capsules) twice daily, administered on an empty stomach at least 1 hour before or 2 hours after a meal or snack. Because pexidartinib is likely to be taken over an extended period of time, the ability to take pexidartinib with a meal would simplify timing of administration and potentially improve compliance. Since administering 400 mg of pexidartinib with a low-fat meal increases exposure by ≈60% relative to the fasted state, administering 250 mg of pexidartinib with a low-fat meal (low-fat meal dosing regimen) was predicted to achieve an exposure similar to 400 mg administered during a fasted state (original dosing regimen). Based on clinical trial simulations with two one-sided t-tests and bootstrapping (ie, resampling) analyses, a bioequivalence study (n = 24) would have >90% power to conclude that the original dosing regimen (400 mg fasted twice daily) and the low-fat meal dosing regimen (250 mg with a low-fat meal twice daily) are bioequivalent. This report provides the outcome of the implementation of the model-informed drug development strategy to recommend and justify a low-fat meal dosing regimen for pexidartinib that has the potential to improve patient compliance while maintaining drug exposure., (© 2023 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Background and Purpose: Intratumour heterogeneity frequently leads to drug resistance, which is a major issue in drug discovery. Drug distribution is one of the key factors for elucidating the resistance mechanism; however, quantitative and regional drug measurement is challenging. Here, we developed a novel ultra-sensitive analytical method and applied it to HER3-targeting antibody-drug conjugate patritumab deruxtecan (HER3-DXd), aiming to explore its payload (DXd) distribution within heterogeneous tissues., Experimental Approach: The developed analytical method is named LDMS-CE-MS, a capillary electrophoresis-mass spectrometry (CE-MS) coupled with a novel sample preconcentration/separation method called "large-volume dual-sample stacking by micelle collapse and sweeping (LDMS)". First, the analytical performance of LDMS-CE-MS for DXd detection was evaluated. Subsequently, we evaluated the bystander effect of HER3-DXd, where tumour tissues were excised from xenograft models and clinical specimens after administration of HER3-DXd. HER3-high expression, adjacent, and HER3-low expression regions were then sampled by laser microdissection to quantify the released DXd., Key Results: LDMS concentrated DXd by 1000-fold and separated it from the hydrophilic bio-matrix through continuous capture and release by the charged micelles, allowing quantification at sub-attomole-level. DXd concentrations decreased in the order of antigen-high expression > adjacent > antigen-low expression regions in the tumour xenograft model, whereas in clinical specimens, adjacent and antigen-high expression regions had approximately the same concentration. These distributions represent a bystander effect., Conclusions and Implications: Our LDMS-CE-MS successfully visualized the attomole-level drug distributions in heterogeneous clinical specimens. This new platform opens a new era of quantitative pharmacokinetic analysis, facilitating drug discovery and development., (© 2022 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Pexidartinib is an oral small-molecule tyrosine kinase inhibitor that selectively targets colony-stimulating factor 1 receptor. Two phase 1 single-center trials were conducted in healthy subjects to determine the absorption, distribution, metabolism, and excretion of pexidartinib using radiolabeled drug and to assess the dose proportionality of pexidartinib following single oral doses. In the mass balance study, eight male subjects received a single oral dose of [ 14 C]-pexidartinib 400 mg with radioactivity assessed in plasma, urine, and feces samples taken at various timepoints postdose. In the dose-proportionality study, 18 subjects received single doses of pexidartinib 200, 400, and 600 mg using randomization sequences. Peak pexidartinib and total radioactivity were observed at 1.75-2.0 hours after the oral dose and then declined in a multiphasic manner. The overall mean recovery of administered radioactivity was 92.2% over 240 hours with 64.8% in the feces and 27.4% in the urine. Major components detected in plasma were pexidartinib and glucuronide (M5, ZAAD-1006a), with M5 and pexidartinib detected in urine and feces, respectively. A glucuronide of dealkylated form (M1) in the urine and multiple oxidized forms (M2, M3, and M4) in feces were detected. The dose-proportionality study found dose-proportional drug exposure between the 200- and 400-mg doses and slightly less than proportional exposure between the 400- and 600-mg doses. These results from these studies provide insight into pexidartinib disposition after oral administration and support the development of dosing guidance in subjects with renal or hepatic impairment or subjects taking cytochrome P450 3A and uridine disphosphate-glucuronosyl transferase inhibitors and inducers., (© 2022 Daiichi Sankyo, Inc. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Patritumab deruxtecan is an antibody-drug conjugate consisting of a fully human monoclonal antibody against human epidermal growth factor receptor 3 (HER3) attached to a topoisomerase I inhibitor payload via a tetrapeptide-based cleavable linker. As part of the pharmacometric analysis informing dose selection for later-stage development, population pharmacokinetics (PK) analysis of patritumab deruxtecan was conducted with pooled serum PK data from patients with HER3-expressing solid tumors (from 3 phase 1/2 studies in breast, lung, and colorectal cancer; N = 425) treated over the dose range of 1.6 to 8.0 mg/kg intravenously every 3 weeks. Population PK modeling for deruxtecan (DXd)-conjugated antibody (representing patritumab deruxtecan) and unconjugated MAAA-1181a (DXd, payload) was carried out sequentially. DXd-conjugated antibody PK was described using a 2-compartment model with parallel linear and nonlinear clearance. Unconjugated DXd PK was described using a 1-compartment model with linear clearance and release of DXd as a first-order, time-dependent function of the level of DXd-conjugated antibody in the central compartment. Preliminary covariate evaluation was conducted for prespecified covariates of pharmacological plausibility and clinical interest. The final model retained weight (on linear clearance and central volume) and albumin level, sex, and tumor type (on linear clearance) for DXd-conjugated antibody, and weight (on release rate constant) and hepatic function (on clearance) for unconjugated DXd. Effects of these covariates on the exposure metrics were generally mild and did not require dose adjustment for subpopulations in subsequent development. Further PK characterization for patritumab deruxtecan will evolve with emerging data., (© 2022 Daiichi Sankyo, Inc and Daiichi Sankyo Co, Ltd. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

HER2-targeted anticancer therapies may be associated with cardiovascular adverse events. This study evaluated effects of the HER2-targeted antibody-drug conjugate trastuzumab deruxtecan (T-DXd, DS-8201a) on QT/QTc interval and its pharmacokinetics. Patients with heavily pretreated, metastatic HER2-expressing breast cancer were enrolled at seven study sites in Japan. T-DXd was administered intravenously at 6.4 mg/kg on day 1 of each 21-day cycle. Primary end points were baseline-adjusted QTcF interval and pharmacokinetics parameters. Key secondary end points included safety events, serum concentration of T-DXd and DXd at the time of electrocardiographic measurements, and antitumor activity parameters. Among 51 total patients, 47 (92.2%) had HER2-low breast cancer (immunohistochemistry 1+ or 2+ and in situ hybridization-negative/equivocal/missing). Pharmacokinetic parameters after a single dose of T-DXd were consistent with previous studies. After multiple doses, T-DXd showed moderate accumulation (accumulation ratio (cycle 3/cycle 1), 1.35), but DXd showed minimal accumulation (1.09). The upper bound of the 90% confidence interval for mean ΔQTcF interval was < 10 ms at all timepoints, and at mean maximum serum concentration was also < 10 ms. Based on concentration-QT analysis, ΔQTcF increased with increasing concentrations of T-DXd and DXd. No clinically meaningful QTcF prolongation was observed. T-DXd had a manageable safety profile and showed antitumor activity in HER2-low breast cancer. In this study, a T-DXd dose of 6.4 mg/kg, higher than the 5.4-mg/kg dose currently approved for breast cancer, was not associated with clinically relevant QTcF prolongation in heavily pretreated patients with HER2-expressing metastatic breast cancer. This study adds to our understanding of T-DXd for treatment of HER2-low breast cancer., (© 2022 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Many mothers need to take some medications during breastfeeding, which may carry a risk to breastfed infants. Thus, determining the amount of a drug transferred into breast milk is critical for risk-benefit analysis of breastfeeding. Breast cancer resistance protein (BCRP), an efflux transporter which usually protects the body from environmental and dietary toxins, was reported to be highly expressed in lactating mammary glands. In this study, we developed a mechanistic lactation physiologically based pharmacokinetic (PBPK) modeling approach incorporating BCRP mediated transport kinetics to simulate the concentration-time profiles of five BCRP drug substrates (acyclovir, bupropion, cimetidine, ciprofloxacin, and nitrofurantoin) in nursing women's plasma and milk. Due to the lack of certain physiological parameters and scaling factors in nursing women, we combine the bottom up and top down PBPK modeling approaches together with literature reported data to optimize and determine a set of parameters that are applicable for all five drugs. The predictive performance of the PBPK models was assessed by comparing predicted pharmacokinetic profiles and the milk-to-plasma (M/P) ratio with clinically reported data. The predicted M/P ratios for acyclovir, bupropion, cimetidine, ciprofloxacin, and nitrofurantoin were 2.48, 3.70, 3.55, 1.21, and 5.78, which were all within 1.5-fold of the observed values. These PBPK models are useful to predict the PK profiles of those five drugs in the milk for different dosing regimens. Furthermore, the approach proposed in this study will be applicable to predict pharmacokinetics of other transporter substrates in the milk., (© 2022 John Wiley & Sons Ltd.)

The estimation of the contributions of UDP-glucuronosyl transferase (UGT) isoforms to the overall metabolism still suffers from technical difficulties due to limited information on enzyme levels in recombinant systems and specific inhibitors, unlike the case for cytochrome P450s (CYPs). The protein expression levels of UGT in both recombinant system microsomes (RM) and human liver microsomes (HLM) were quantified using liquid chromatography-tandem mass spectrometry, and the relative expression factor (REF) value of HLM to recombinant microsomes was estimated to evaluate the fractions of drug metabolism by a single UGT enzyme (fmUGT) of UGT substrates. The REF values of UGT1A1, UGT1A3, UGT1A9, UGT2B4, UGT2B7, and UGT2B17 were 0.228, 0.0714, 0.0665, 0.420, 0.118, and 0.0442, respectively. fmUGTs in HLM were estimated for several typical UGT substrates utilizing these values and metabolic clearances in RM. These values were comparable to the reported values estimated by various methods. This study provided useful information on REF values, which promote a robust estimation of fmUGT values for UGT substrates when evaluating the contribution of UGT isoforms to total metabolic clearance., (© 2022 John Wiley & Sons Ltd.)

The International Consortium for Innovation and Quality (IQ) Physiologically Based Pharmacokinetic (PBPK) Modeling Induction Working Group (IWG) conducted a survey across participating companies around general strategies for PBPK modeling of induction, including experience with its utility to address various questions, regulatory interactions, and regulatory acceptance. The results highlight areas where PBPK modeling is used with high confidence and identifies opportunities where confidence is lower and further evaluation is needed. To enhance the survey results, the PBPK-IWG also collected case studies and analyzed recent literature examples where PBPK models were applied to predict CYP3A induction-mediated drug-drug interactions. PBPK modeling of induction has evolved and progressed significantly, proving to have great potential to accelerate drug discovery and development. With the aim of enabling optimal use for new molecular entities that are either substrates and/or inducers of CYP3A, the PBPK-IWG proposes initial workflows for PBPK application, discusses future trends, and identifies gaps that need to be addressed., (© 2021 The Authors. Clinical Pharmacology & Therapeutics © 2021 American Society for Clinical Pharmacology and Therapeutics.)

Pexidartinib is a novel oral small-molecule tyrosine kinase inhibitor targeting the colony-stimulating factor 1 receptor. Pexidartinib undergoes extensive hepatic metabolism via multiple cytochrome P450 and uridine 5'-diphospho-glucuronosyl transferase enzymes, with ZAAD-1006a as the only major metabolite in human plasma. As pexidartinib is extensively metabolized, hepatic impairment (HI) could lead to increased exposure to pexidartinib. The objective of the two phase 1, open-label studies was to determine the pharmacokinetics of pexidartinib after a single 200-mg dose in subjects with mild and moderate HI, based on Child-Pugh classification (PL3397-A-U123: 8 mild HI and 8 moderate HI vs 16 matched healthy controls) and National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria (PL3397-A-U129: 8 moderate HI versus 8 matched healthy controls [NCT04223635]). Based on Child-Pugh classification, exposure to pexidartinib (maximum observed concentration [C max ], area under the plasma concentration-time curve up to the last measurable concentration [AUC last ], and extrapolated to infinity [AUC inf ]) was similar in subjects with mild and moderate HI and in respective matched healthy controls, whereas ZAAD-1006a exposure (AUC) was approximately 27% to 28% and 41% to 48% higher in mild and moderate HI, respectively. According to NCI-ODWG criteria, total pexidartinib exposure was 42% to 46% higher in subjects with moderate HI, compared with healthy controls, and total ZAAD-1006a exposure was 70% to 79% higher for subjects with moderate HI, compared with matched healthy controls with normal hepatic function. These findings were used to develop appropriate dose recommendations in patients with hepatic impairment., (© 2022 Daiichi Sankyo Inc. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

We assessed the bioequivalence of a single dose of 5-mg of esaxerenone administered as an orally disintegrating tablet (ODT) with the conventional oral tablet in healthy Japanese men. This single-center, open-label, randomized, two-drug, two-stage crossover, single-dose study was conducted in two parts. In study 1, both formulations were taken with water. In study 2, only the ODT formulation was taken without water. The primary outcome was the evaluation of bioequivalence of the ODT and conventional tablet using the pharmacokinetic (PK) parameters maximum plasma concentration (C max ) and area under the plasma concentration-time curve to the last quantifiable time (AUC last ). Plasma concentrations were measured using a validated liquid chromatography/mass spectrometry method and PK parameters were calculated by noncompartmental analysis. The ratios of the geometric least-squares mean (2-sided 90% confidence intervals [90%CIs]) for ODT with (study 1) and without (study 2) water to the conventional tablet were 1.03 (1.00-1.07) and 1.01 (0.96-1.06) for C max and 1.03 (1.00-1.07) and 0.96 (0.94-0.98) for AUC last , respectively. The 90%CIs fell within the predefined bioequivalence range of 0.80-1.25. Treatment-emergent adverse events were similar between both formulations. In conclusion, esaxerenone 5-mg ODT taken with or without water was bioequivalent to a single 5-mg conventional oral tablet., (© 2022 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Objective: To determine senescence-associated changes in the gingival tissues of aged mice and gingival fibroblast cultures., Materials and Methods: The production of senescence-associated β-galactosidase (SA-β-gal) and mRNA expression of p16, p21, interleukin (IL)-1β, and tumor necrosis factor α (TNF-α) were evaluated in gingival tissues, gingival fibroblasts of 10- and 20-month-old C57BL/6NCrl mice, and multiple-passaged and hydrogen peroxide-stimulated human gingival fibroblasts (HGFs). Changes in molecular expression in HGF cultures due to senescent cell elimination by the senolytic drug ABT-263 (Navitoclax) were analyzed., Results: Compared to 10-week-old mice, the 20-month-old mice had higher numbers of M1 macrophages. The proportion of cells expressing SA-β-gal were also higher in 20- month-old mice than in 10-week-old-mice. Gingival fibroblasts in 20-month-old mice expressed less collagen 1a1, collagen 4a1, and collagen 4a2 mRNA than those in 10-week-old mice. Compared to control cells, H2O2 treated HGF cells expressed higher levels of SA-β-gal and p16, p21, IL-1β, and TNF-α. Furthermore, ABT-263 suppressed HGF cell expression of cytokines after senescence induction., Conclusions: Senescence-associated changes were observed in the gingival tissues of aged mice and HGF cultures. In addition, the potential of senolytic drugs to modify aging-related changes in the gingiva was shown., (© 2022 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

Edoxaban 60 mg is approved for stroke prevention in patients with atrial fibrillation (AF) not fulfilling any dose-reduction criteria. As edoxaban is partially renally cleared (≈50%), this study compared pharmacokinetics (PK) and pharmacodynamics of edoxaban 60 mg once daily with edoxaban 75 mg once daily in patients with AF with high renal clearance (creatinine clearance > 100 mL/min) over 12 months. Primary PK and pharmacodynamics end points were plasma edoxaban exposure and anti-factor Xa (FXa) concentration. A population PK model estimated edoxaban exposure at steady state. Efficacy and safety outcomes included composites of stroke, transient ischemic attack, systemic embolism, and major and clinically relevant nonmajor bleeding. Of 607 patients, 303 and 304 were randomized to edoxaban 60 and 75 mg, respectively. Edoxaban 75 mg provided ≈25% higher exposure than 60 mg. This increase was accurately depicted in the population PK model; anti-factor Xa concentration correlated with edoxaban exposure. Rates of composite and individual outcomes were similarly low between doses. In conclusion, the 25% increase in edoxaban dose (60-75 mg) resulted in ≈25% exposure increase in the 75-mg group. Higher exposure was not associated with reduced stroke risk in patients with AF with high renal clearance., (© 2021 Daiichi Sankyo Inc. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Purpose: Drug utilization research (DUR) contributes to inform policymaking and to strengthen health systems. The availability of data sources is the first step for conducting DUR. However, documents that systematize these data sources in Latin American (LatAm) countries are not known. We compiled the potential data sources for DUR in the LatAm region., Methods: A network of DUR experts from nine LatAm countries was assembled and experts conducted: (i) a website search of the government, academic, and private health institutions; (ii) screening of eligible data sources, and (iii) liaising with national experts in pharmacoepidemiology (via an online survey). The data sources were characterized by accessibility, geographic granularity, setting, sector of the data, sources and type of the data. Descriptive analyses were performed., Results: We identified 125 data sources for DUR in nine LatAm countries. Thirty-eight (30%) of them were publicly and conveniently available; 89 (71%) were accessible with limitations, and 18 (14%) were not accessible or lacked clear rules for data access. From the 125 data sources, 76 (61%) were from the public sector only; 46 (37%) were from pharmacy records; 43 (34%) came from ambulatory settings and; 85 (68%) gave access to individual patient-level data., Conclusions: Although multiple sources for DUR are available in LatAm countries, the accessibility is a major challenge. The procedures for accessing DUR data should be transparent, feasible, affordable, and protocol-driven. This inventory could permit a comparison of drug utilization between countries identifying potential medication-related problems that need further exploration., (© 2021 John Wiley & Sons Ltd.)

An addendum of the ICH E9 guideline on Statistical Principles for Clinical Trials was released in November 2019 introducing the estimand framework. This new framework aims to align trial objectives and statistical analyses by requiring a precise definition of the inferential quantity of interest, that is, the estimand. This definition explicitly accounts for intercurrent events, such as switching to new anticancer therapies for the analysis of overall survival (OS), the gold standard in oncology. Traditionally, OS in confirmatory studies is analyzed using the intention-to-treat (ITT) approach comparing treatment groups as they were initially randomized regardless of whether treatment switching occurred and regardless of any subsequent therapy (treatment-policy strategy). Regulatory authorities and other stakeholders often consider ITT results as most relevant. However, the respective estimand only yields a clinically meaningful comparison of two treatment arms if subsequent therapies are already approved and reflect clinical practice. We illustrate different scenarios where subsequent therapies are not yet approved drugs and thus do not reflect clinical practice. In such situations the hypothetical strategy could be more meaningful from patient's and prescriber's perspective. The cross-industry Oncology Estimand Working Group (www.oncoestimand.org) was initiated to foster a common understanding and consistent implementation of the estimand framework in oncology clinical trials. This paper summarizes the group's recommendations for appropriate estimands in the presence of treatment switching, one of the key intercurrent events in oncology clinical trials. We also discuss how different choices of estimands may impact study design, data collection, trial conduct, analysis, and interpretation., (© 2021 John Wiley & Sons Ltd.)

This analysis was conducted to assess exposure-response relationships for efficacy and safety of pexidartinib in patients with tenosynovial giant cell tumor. Efficacy was assessed categorically by overall response rate (ORR) with Response Evaluation Criteria in Solid Tumors version 1.1 and longitudinally (changes in tumor size and volume). Safety included hepatic parameters (i.e., alanine aminotransferase [ALT], aspartate aminotransferase [AST], and total bilirubin). Average pexidartinib concentration (C avg ) was identified as the primary exposure parameter correlated with response. In categorical and longitudinal analyses, higher C avg coincided with greater ORR and tumor size reduction, respectively, with smaller joint size having a greater impact. For safety, a significant relationship was observed between C avg and incidence of ALT-related and AST-related adverse events (AEs). With increased exposure, an increase in efficacy was predicted with near maximum effect at 800 mg/day. Higher initial dose (1000 mg/day) during the first 2 weeks did not improve efficacy. Higher doses were associated with an increased risk of ALT-related and AST-related AEs. These results support the US Food and Drug Administration-approved dose (400 mg two times/day without initial loading dose)., (© 2021 Daiichi Sankyo, Inc. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Trastuzumab deruxtecan (T-DXd) is a HER2-targeting antibody-drug conjugate composed of a novel enzyme-cleavable linker and membrane-permeable topoisomerase I inhibitor payload. T-DXd has been approved for HER2-positive metastatic breast cancer and for HER2-positive metastatic gastric cancer. The approval in breast cancer was based on results from the DESTINY-Breast01 (U201; NCT03248492) and J101 (NCT02564900) trials. Here, we present dose justification for the approved 5.4 mg/kg every-3-weeks (Q3W) dose based on exposure-efficacy evaluated in patients with HER2-positive breast cancer (N = 337) from these 2 trials. Exposure-safety was assessed in patients with all tumor types (N = 639, n = 512 with breast cancer) across 5 trials, including J101 and DESTINY-Breast01. T-DXd doses ranged from 0.8-8.0 mg/kg Q3W; most patients received 5.4 (n = 312) or 6.4 mg/kg (n = 291). For each end point, multivariate logistic or Cox regression analysis was performed using various exposure metrics of T-DXd and released drug. A statistically significant association was observed between intact T-DXd area under the concentration-time curve (AUC) and confirmed objective response rate (ORR; P = 0.028). No significant exposure-response relationships were observed between intact T-DXd or released drug and duration of response or progression-free survival; however, follow-up was limited. All evaluated safety end points demonstrated a significant (P < 0.05) relationship with either intact T-DXd or released drug, with higher adverse event (AE) rates projected at higher exposures. Dose-response projections suggested an increase in ORR (67.5% vs. 62.9%) and toxicity (e.g., grade ≥ 3 all-cause treatment-emergent AEs: 61% vs. 54%) with T-DXd 6.4 vs. 5.4 mg/kg. Results demonstrate the benefit-risk profile at different doses and guide clinicians in the use of the 5.4-mg/kg Q3W dose in patients with HER2-positive metastatic breast cancer., (© 2021 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

When comparing survival times of treatment and control groups under a more realistic nonproportional hazards scenario, the standard log-rank (SLR) test may be replaced by a more efficient weighted log-rank (WLR) test, such as the Fleming-Harrington (FH) test. Designing a group-sequential clinical trial with one or more interim looks during which a FH test will be performed, necessitates correctly quantifying the information fraction (IF). For SLR test, IF is defined simply as the ratio of interim to final numbers of events; but for FH test, it can deviate substantially from this ratio. In this article, we separate the effect of weight function (of FH test) alone on IF from the effect of censoring. We have shown that, without considering the effect of censoring, IF can be derived analytically for FH test using information available at the design stage and the additional effect due to censoring is relatively smaller. This article intends to serve two major purposes: first, to emphasize and rationalize the deviation of IF in weighted log-rank test from that of SLR test which is often overlooked (Jiménez, Stalbovskaya, and Jones); second, although it is impossible to predict IF for a weighted log-rank test at the design stage, our decomposition of effects on IF provides a reasonable and practically feasible range of IF to work with. We illustrate our approach with an example and provide simulation results to evaluate operating characteristics., (© 2021 John Wiley & Sons, Ltd.)

Trastuzumab deruxtecan (DS-8201) is a human epidermal growth factor receptor 2 (HER2)-targeting antibody-drug conjugate with a novel enzyme-cleavable linker, a topoisomerase I inhibitor payload, and a drug-to-antibody ratio of ≈ 8. We have characterized the population pharmacokinetics (PK) of trastuzumab deruxtecan and released drug (topoisomerase I inhibitor) in patients with HER2-positive breast cancer or other solid tumor malignancies. This analysis includes pooled data from five clinical studies with 639 patients. Trastuzumab deruxtecan doses ranged from 0.8 to 8.0 mg/kg every 3 weeks. Serum concentrations of trastuzumab deruxtecan and released drug were analyzed using a sequential two-step approach, with the nonlinear mixed-effects modeling methods. Covariate assessment was based upon stepwise forward-addition and backward-elimination process, followed by both univariate and multivariate analysis quantifying their impact on steady-state exposure of trastuzumab deruxtecan and released drug. A two-compartment model with linear elimination best described PK profiles of intact trastuzumab deruxtecan, while a one-compartment model with time-varying release-rate constant and linear elimination described released-drug PK profiles. Statistically significant covariates (country, tumor size, sex, formulation, age, body weight, albumin, total bilirubin, and aspartate aminotransferase) resulted in < 20% change in steady-state area under the concentration-time curve of trastuzumab deruxtecan and released drug, except for increased body weight (95th percentile, 86 kg) and decreased albumin (5th percentile, 31 g/L). Analysis of patients stratified by country, race, renal function, and hepatic function found no clinically meaningful differences in steady-state exposure of intact trastuzumab deruxtecan or released drug. Overall, results suggest that no dose adjustment based on tested covariates or in specific patient populations is warranted., (© 2020 Daiichi Sankyo Inc. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Pexidartinib is a kinase inhibitor that induces tumor response and improvements in symptoms and functional outcomes in adult patients with symptomatic tenosynovial giant cell tumor (TGCT). A population pharmacokinetic (PK) model for pexidartinib and its metabolite, ZAAD, was developed, and effects of demographic and clinical factors on the PK of pexidartinib and ZAAD were estimated. The analysis included pooled data from 7 studies in healthy volunteers (N = 159) and 2 studies in patients with TGCT or other solid tumors (N = 216). A structural 2-compartment model with sequential zero- and first-order absorption and lag time, and linear elimination from the central compartment adequately described pexidartinib and ZAAD PKs. Clearance of pexidartinib was estimated at 5.83 L/h in a typical patient with reference covariates (male, non-Asian, weight = 80 kg, creatinine clearance ≥90 mL/min, aspartate aminotransferase ≤80 U/L, and total bilirubin ≤20.5 μmol/L). In the covariate analysis, Asians and healthy subjects had modestly lower pexidartinib exposure (21% decrease each) in terms of steady-state area under the curve values from 0 to 24 hours (AUC 0-24,ss ). Effects of body weight, sex, and hepatic function parameters on pexidartinib AUC 0-24,ss were generally <20%. Patients with TGCT with mild renal impairment were predicted to have approximately 23% higher AUC 0-24,ss than those with normal renal function. The effects of covariates on ZAAD exposure were similar to those on pexidartinib. These results indicate small and generally clinically nonmeaningful effects of patient demographic and clinical characteristics on pexidartinib and ZAAD PK profiles., (© 2020 Daiichi Sankyo, Inc. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)