Imeglimin population pharmacokinetics and dose adjustment predictions for renal impairment in Japanese and Western patients with type 2 diabetes

Imeglimin is an orally administered first-in-class drug to treat type 2 diabetes mellitus (T2DM) and is mainly excreted unchanged by the kidneys. The present study aimed to define the pharmacokinetic (PK) characteristics of imeglimin using population PK analysis and to determine the optimal dosing regimen for Japanese patients with T2DM and chronic kidney disease (CKD). Imeglimin plasma concentrations in Japanese and Western healthy volunteers, and patients with T2DM, including patients with mild to severe CKD with an estimated glomerular filtration rate (eGFR) > 14 mL/min/1.73 m² were included in a population PK analysis. Pharmacokinetic simulations were conducted using a population PK model, and the area under concentration-time curve (AUC) was extrapolated with power regression analysis to lower eGFR. The influence of eGFR, weight, and age on apparent clearance and of dose on relative bioavailability were quantified by population PK analysis. Simulations and extrapolation revealed that the recommended dosing regimen based on the AUC was 500 mg twice daily (b.i.d.) for patients with eGFR 15-45 mL/min/1.73 m² , and 500 mg with a longer dosing interval was suggested for those with eGFR < 15. Simulations revealed that differences in plasma AUCs between Japanese and Western patients at the same dose were mainly driven by a difference in the eGFR and that the plasma AUC after 1,000 and 1,500 mg b.i.d. in Japanese and Western patients, respectively, was comparable in the phase IIb studies. These results indicate suitable dosages of imeglimin in the clinical setting of T2DM with renal impairment.

First-in-human trial of the PI3Kβ-selective inhibitor SAR260301 in patients with advanced solid tumors

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.

IMI - oral biopharmaceutics tools project - evaluation of bottom-up PBPK prediction success part 1: Characterisation of the OrBiTo database of compounds

Predicting oral bioavailability (F_oral) is of importance for estimating systemic exposure of orally administered drugs. Physiologically-based pharmacokinetic (PBPK) modelling and simulation have been applied extensively in biopharmaceutics recently. The Oral Biopharmaceutical Tools (OrBiTo) project (Innovative Medicines Initiative) aims to develop and improve upon biopharmaceutical tools, including PBPK absorption models. A large-scale evaluation of PBPK models may be considered the first step. Here we characterise the OrBiTo active pharmaceutical ingredient (API) database for use in a large-scale simulation study. The OrBiTo database comprised 83 APIs and 1475 study arms. The database displayed a median logP of 3.60 (2.40-4.58), human blood-to-plasma ratio of 0.62 (0.57-0.71), and fraction unbound in plasma of 0.05 (0.01-0.17). The database mainly consisted of basic compounds (48.19%) and Biopharmaceutics Classification System class II compounds (55.81%). Median human intravenous clearance was 16.9L/h (interquartile range: 11.6-43.6L/h; n=23), volume of distribution was 80.8L (54.5-239L; n=23). The majority of oral formulations were immediate release (IR: 87.6%). Human F_oral displayed a median of 0.415 (0.203-0.724; n=22) for IR formulations. The OrBiTo database was found to be largely representative of previously published datasets. 43 of the APIs were found to satisfy the minimum inclusion criteria for the simulation exercise, and many of these have significant gaps of other key parameters, which could potentially impact the interpretability of the simulation outcome. However, the OrBiTo simulation exercise represents a unique opportunity to perform a large-scale evaluation of the PBPK approach to predicting oral biopharmaceutics.

Optimizing pharmacokinetic bridging studies in paediatric oncology using physiologically-based pharmacokinetic modelling: application to docetaxel

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.

Absence of interaction of cabazitaxel on the pharmacokinetics of midazolam: Results of a drug–drug interaction study in patients with advanced solid tumors

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Background: Cabazitaxel (Cbz) is approved in combination with prednisone/prednisolone for the treatment of men with hormone-refractory metastatic prostate cancer previously treated with a docetaxel-containing treatment regimen. In vitro studies showed that Cbz is mainly metabolized through CYP3A, resulting in inhibition of this family of enzymes. Midazolam (Mdz) is primarily metabolized by CYP3A4. We aimed to determine the effect of Cbz on CYP3A activity by comparing the pharmacokinetic (PK) properties of Mdz when administered alone and following co-administration with Cbz. Methods: An ongoing safety and PK study of Cbz in patients with metastatic or locally advanced solid tumors and varying degrees of hepatic impairment (NCT01140607) included a cohort with normal hepatic function to assess the effect of a single Cbz dose on the PK profile of a single dose of Mdz. This was an open-label, two-period, fixed-sequence study in patients aged between 45 and 60 years with advanced solid tumors and normal hepatic function. A single dose of Mdz (2 mg) was administered orally alone (Day –1) and at the end of a 1-hour infusion of Cbz (25 mg/m2) (Day 1), with a 24-hour interval between the two administrations of Mdz. Endpoints included AUC and AUClastof Mdz with and without Cbz administration, and safety evaluations. Results: Of the 13 patients enrolled and treated in the cohort, 11 patients were included in the PK analysis. Exposure (AUC and AUClast) and other PK parameters after a single administration of Mdz alone and in combination with Cbz (Day 1) were similar. The AUC ratio for Mdz administered alone or with Cbz was 0.97 (90% CI: 0.76–1.23). The AUClast ratio for Mdz administered alone or with Cbz was 1.04 (90% CI: 0.81–1.34). All 13 patients had ≥1 adverse event (AE), 11 (84.6%) experienced a Grade 3–4 AE, and 4 (30.8%) experienced a serious AE. The majority of Grade 3–4 AEs were haematological and no new or unexpected safety findings were observed. Conclusions: In this study, Cbz did not increase the plasma exposure of Mdz. This indicates that Cbz is not a CYP3A inhibitor in the clinical setting and can be administered in combination with drugs metabolized by CYP3A. Clinical trial information: NCT01140607.

Cabazitaxel plus cisplatin coadministration and drug-interaction study in patients with advanced solid tumors

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Background: Cabazitaxel (Cbz) is a novel taxane with in vivo efficacy in taxane-sensitive and -resistant tumors. Therapeutic synergism of Cbz/cisplatin (Cis) has been shown in tumor-bearing mice. Since Cbz is primarily metabolized by CYP3A, drug interactions may occur with modulators of CYP3A. Methods: The primary objective of part 1 of this phase I study (NCT00925743) was to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of Cbz/Cis. Secondary objectives included safety, pharmacokinetics (PK) and efficacy. The objective of part 2 was to assess efficacy at the MTD. The effect of the antiemetic aprepitant (a moderate CYP3A inhibitor) on the PK of Cbz was also examined. Eligible patients (pts) had ECOG PS ≤ 1 and confirmed metastatic or unresectable solid tumors for which Cis therapy was considered appropriate. A 3 + 3 dose escalation at a starting dose (level 0) of 20/75 mg/m2 (Cbz/Cis), administered IV Q3W, was used. The MTD was the highest dose at which 0/3 or ≤ 1/6 pts experienced a DLT in Cycle 1. Results: Pts (n = 25; 10 in part 1; 15 in part 2) with a median age of 56 yrs were enrolled. The most frequent primary tumors were lung (n = 4), prostate, ovary and pancreas (each n = 2). Of 6 evaluable pts, 2 had a DLT at dose level 0 (Grade 3 acute renal failure; febrile neutropenia). The MTD was 15/75 mg/m2 as no DLTs were observed; 18 pts were treated at the MTD and 60 cycles were administered (median = 3; range 1–8). The most frequent non-hematologic treatment-related adverse events (all grades/grade 3–4) were nausea (78%/22%), vomiting (72%/11%), fatigue (61%/17%), anorexia (67%/11%) and diarrhea (44%/0%). Incidence of grade 3–4 neutropenia was 78%; 1 pt had febrile neutropenia. The combined PK profile of Cbz/Cis did not appear to differ vs those of the single agents. The ratio of Cbz clearance with vs without aprepitant co-administration was 0.81 (90% CI 0.36–1.85). Stable disease was seen in 11 pts; 1 pt (prostate carcinoma) had an unconfirmed partial response. Conclusions: The MTD of Cbz/Cis was 15/75 mg/m2. The combination had a manageable safety profile consistent with a platinum/taxane combination. No PK interactions between Cis and Cbz were seen; aprepitant did not appear to alter the PK of Cbz.

Phase I trial of cabazitaxel plus cisplatin in patients with advanced solid tumors

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Background: Cabazitaxel (Cbz) is a novel taxane with broad in vivo efficacy in taxane-sensitive and -resistant tumors. Clinical activity of Cbz was confirmed in the Phase III TROPIC trial ( NCT00417079 ); Cbz significantly improved overall survival compared with mitoxantrone in patients (pts) with metastatic castration-resistant prostate cancer whose disease had progressed during or after a prior docetaxel-containing regimen. Therapeutic synergism of Cbz/cisplatin (Cis) has been demonstrated in tumor-bearing mice.

Methods: The primary objective in part 1 of this Phase I study ( NCT00925743 ) was to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of Cbz/Cis. Secondary objectives were safety, pharmacokinetics (PK) and efficacy. The primary objective of part 2 was to determine the antitumor activity at the MTD. Eligible pts were ≥ 18 yrs, ECOG PS ≤ 1, with confirmed metastatic or unresectable solid tumors for which Cis therapy was considered appropriate. A 3 + 3 dose escalation with a starting dose (level 0) of 20/75 mg/m2 (Cbz/Cis), administered IV Q3W, was used. The MTD was the highest dose at which 0/3 or ≤ 1/6 pts experienced a DLT in Cycle 1.

Results: Pts (N = 25; 10 in part 1; 15 in part 2) with a median age of 56 yrs were enrolled. The most frequent primary tumors were lung (n = 4), prostate, ovary and pancreas (each n = 2). 2 of 6 evaluable pts experienced a DLT at dose level 0 (Grade 3 acute renal failure; febrile neutropenia). The MTD was 15/75 mg/m2 as no DLTs were observed. Eighteen pts were treated at the MTD and 60 cycles were administered (median = 3; range 1–8). The most frequent non-hematologic treatment-related adverse events (all Grade/Grade 3–4) were nausea (78%/22%), vomiting (72%/11%), fatigue (61%/17%), anorexia (67%/11%) and diarrhea (44%/0%). Incidence of Grade 3–4 neutropenia was 78% and 1 pt had febrile neutropenia. No PK interactions between Cbz and Cis were observed. Stable disease was seen in 11 pts. No objective responses were reported.

Conclusions: The MTD of Cbz/Cis was 15/75 mg/m2. The combination had a manageable safety profile consistent with that of a platinum/taxane combination. No PK interactions were seen. Further investigations into the combined treatment combination are planned.