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Efficacy of drugs aimed at treating central nervous system (CNS) disorders rely partly on their ability to cross the cerebral endothelium, also called the blood-brain barrier (BBB), which constitutes the main interface modulating exchanges of compounds between the brain and blood. In this work, we used both, conventional pharmacokinetics (PK) approach and in situ brain perfusion technique to study the blood and brain PK of PKRinh, an inhibitor of the double-stranded RNA-dependent protein kinase (PKR) activation, in mice. PKRinh showed a supra dose-proportional blood exposure that was not observed in the brain, and a brain to blood AUC ratio of unbound drug smaller than 1 at all tested doses. These data suggested the implication of an active efflux at the BBB. Using in situ brain perfusion technique, we showed that PKRinh has a very high brain uptake clearance which saturates with increasing concentrations. Fitting the data to a Michaelis-Menten equation revealed that PKRinh transport through the BBB is composed of a passive unsaturable flux and an active saturable protein-mediated efflux with a k m of ≅ 3 μM. We were able to show that the ATP-binding cassette (ABC) transporter P-gp (Abcb1), but not Bcrp (Abcg2), was involved in the brain to blood efflux of PKRinh. At the circulating PKRinh concentrations of this study, the P-gp was not saturated, in accordance with the linear brain PKRinh PK. Finally, PKRinh had high brain uptake clearance (14 μl/g/s) despite it is a good P-gp substrate (P-gp Efflux ratio ≅ 3.6), and reached similar values than the cerebral blood flow reference, diazepam, in P-gp saturation conditions. With its very unique brain transport properties, PKRinh improves our knowledge about P-gp-mediated efflux across the BBB for the development of new CNS directed drugs. [ABSTRACT FROM AUTHOR]

A joint modeling framework was developed using data from 75 patients of early amcenestrant phase I–II AMEERA‐1‐2 dose escalation and expansion cohorts. A semi‐mechanistic tumor growth inhibition (TGI) model was developed. It accounts for the dynamics of sensitive and resistant tumor cells, an exposure‐driven effect on tumor proliferation of sensitive cells, and a delay in the initiation of treatment effect to describe the time course of target lesion tumor size (TS) data. Individual treatment exposure overtime was introduced in the model using concentrations predicted by a population pharmacokinetic model of amcenestrant. This joint modeling framework integrated complex RECISTv1.1 criteria information, linked TS metrics to progression‐free survival (PFS), and was externally evaluated using the randomized phase II trial AMEERA‐3. We demonstrated that the instantaneous rate of change in TS (TS slope) was an important predictor of PFS and the developed joint model was able to predict well the PFS of amcenestrant phase II monotherapy trial using only early phase I–II data. This provides a good modeling and simulation tool to inform early development decisions. [ABSTRACT FROM AUTHOR]

Background: Phosphoinositide 3-kinase (PI3K) β is the dominant isoform for PI3K activity in many phosphatase and tensin homolog (PTEN)-deficient tumor models. This was a first-in-human study to determine the maximum tolerated dose, safety, pharmacokinetics (PK), pharmacodynamics, and preliminary activity of SAR260301, a potent PI3Kβ-selective inhibitor (clinicaltrials.gov identifier NCT01673737).Methods: Successive cohorts of patients with advanced solid tumors received increasing doses of oral SAR260301 according to a Bayesian escalation with an overdose-control process based on the occurrence of dose-limiting toxicity in the first 28-day cycle. Adverse events, tumor response, PK, and the effect of food on PK were evaluated. Target engagement was assessed in platelets. Physiologically-based PK modeling was used for exposure predictions.Results: Twenty-one patients received treatment at doses ranging from 100 mg once daily to 440 mg/m2 twice daily. Dose-limiting toxicities included 1 episode of grade 3 pneumonitis (400 mg twice daily) and 1 grade 3 γ-glutamyltransferase increase (600 mg twice daily). The maximum tolerated dose was not reached. The most frequently occurring treatment-related adverse events were nausea, vomiting, and diarrhea (14% each). Pharmacologically active concentrations were reached, but SAR260301 was rapidly cleared, and exposures associated with antitumor activity in preclinical models were not maintained at the highest dose tested. Food further decreased SAR260301 exposure.Conclusions: SAR260301 had an acceptable safety profile, but exposure sufficient to inhibit the PI3K pathway was unachievable because of rapid clearance, and clinical development was terminated. These results demonstrate the importance of PK and pharmacodynamic assessments in early drug development. Cancer 2018;124:315-24. © 2017 American Cancer Society. [ABSTRACT FROM AUTHOR]

Aim Applying physiologically-based pharmacokinetic (PBPK) modelling in paediatric cancer drug development is still challenging. We aimed to demonstrate how PBPK modelling can be applied to optimize dose and sampling times for a paediatric pharmacokinetic (PK) bridging study in oncology and to compare with the allometric scaling population PK (AS-popPK) approach, using docetaxel as an example. Methods A PBPK model for docetaxel was first developed for adult cancer patients using Simcyp® and subsequently used to predict its PK profiles in children by accounting for age-dependent physiological differences. Dose (mg m-2) requirements for children aged 0-18 years were calculated to achieve targeted exposure in adults. Simulated data were then analyzed using population PK modelling with MONOLIX® in order to perform design optimization with the population Fisher information matrix (PFIM). In parallel, the AS-popPK approach was performed for the comparison. Results The PBPK model developed for docetaxel adequately predicted its PK profiles in both adult and paediatric cancer patients (predicted clearance and volume of distribution within 1.5 fold of observed data). The revised dose of docetaxel for a child over 1.5 years old was higher than the adult dose. Considering clinical constraints, the optimal design contained two groups of 15 patients, having three or four sampling times and had good predicted relative standard errors (RSE<30%) for almost all parameters. The AS-popPK approach performed reasonably well but could not predict for very young children. Conclusion This research shows the clinical utility of PBPK modelling in combination with population PK modelling and optimal design to support paediatric oncology development. [ABSTRACT FROM AUTHOR]

The inducible p25 overexpression mouse model recapitulate many hallmark features of Alzheimer's disase including progressive neuronal loss, elevated Aβ, tau pathology, cognitive dysfunction, and impaired synaptic plasticity. We chose p25 mice to evaluate the physical and functional integrity of the blood-brain barrier (BBB) in a context of Tau pathology (pTau) and severe neurodegeneration, at an early (3 weeks ON) and a late (6 weeks ON) stage of the pathology. Using in situ brain perfusion and confocal imaging, we found that the brain vascular surface area and the physical integrity of the BBB were unaltered in p25 mice. However, there was a significant 14% decrease in cerebrovascular volume in 6 weeks ON mice, possibly explained by a significant 27% increase of collagen IV in the basement membrane of brain capillaries. The function of the BBB transporters GLUT1 and LAT1 was evaluated by measuring brain uptake of d -glucose and phenylalanine, respectively. In 6 weeks ON p25 mice, d -glucose brain uptake was significantly reduced by about 17% compared with WT, without any change in the levels of GLUT1 protein or mRNA in brain capillaries. The brain uptake of phenylalanine was not significantly reduced in p25 mice compared with WT. Lack of BBB integrity, impaired BBB d -glucose transport have been observed in several mouse models of AD. In contrast, reduced cerebrovascular volume and an increased basement membrane thickness may be more specifically associated with pTau in mouse models of neurodegeneration. • The physical integrity of the blood-brain barrier is not altered after 6 weeks of induction of the p25 transgene (6 weeks ON). • The cerebrovascular volume is decreased after 6 weeks ON. • The basement membrane thickness is increased after 6 weeks ON. • Unlike phenylalanine transport, d -glucose cerebral uptake is reduced after 6 weeks ON. [ABSTRACT FROM AUTHOR]

Abstract: Background: To determine dose-limiting toxicities (DLTs), recommended phase II trial dose (RPTD), safety, preliminary antitumour activity and pharmacokinetics of intravenous aflibercept with irinotecan, 5-fluorouracil and leucovorin (LV5FU2). Patients and methods: In this open-label study, 38 patients with advanced solid tumours received aflibercept 2, 4, 5, or 6mg/kg on day 1, then irinotecan and LV5FU2 on days 1 and 2 every 2weeks. Results: Two grade 3/4 aflibercept-associated DLTs occurred with 4mg/kg: proteinuria lasting >2weeks and acute nephrotic syndrome with thrombotic microangiopathy. Two DLTs with 5mg/kg (grade 3 stomatitis and grade 3 oesophagitis reflux) and three with 6mg/kg (febrile neutropenia, grade 3 stomatitis and grade 3 abdominal pain) were considered related to concurrent chemotherapy and underlying disease. The most common grade 3/4 adverse events were neutropenia, hypertension and diarrhoea. Nine patients had partial responses, five with 4mg/kg. Twenty-two patients had stable disease (five with 4mg/kg), lasting >3months in 17 patients. No anti-aflibercept antibodies were detected. Free aflibercept was in excess of bound in most patients on 4mg/kg. Conclusion: Based on pharmacokinetics, acceptable safety and encouraging antitumour activity, aflibercept 4mg/kg was selected as the RPTD with irinotecan and LV5FU2 every 2weeks. [Copyright &y& Elsevier]