In vitro and clinical investigations to determine the drug-drug interaction potential of entrectinib, a small molecule inhibitor of neurotrophic tyrosine receptor kinase (NTRK)

Background Entrectinib is a CNS-active, potent inhibitor of tyrosine receptor kinases A/B/C, ROS1 and anaplastic lymphoma kinase approved for use in patients with solid tumors. We describe the in vitro and clinical studies investigating potential entrectinib drug-drug interactions. Methods In vitro studies with human biomaterials assessed the enzymes involved in entrectinib metabolism, and whether entrectinib modulates the activity of the major cytochrome P450 (CYP) enzymes or drug transporter P-glycoprotein. Clinical studies investigated the effect of a strong CYP3A4 inhibitor (itraconazole) and inducer (rifampin) on single-dose entrectinib pharmacokinetics. The effect of entrectinib on sensitive probe substrates for CYP3A4 (midazolam) and P-glycoprotein (digoxin) were also investigated. Results Entrectinib is primarily metabolized by CYP3A4. In vitro, entrectinib is a CYP3A4/5 inhibitor (IC50 2 μM) and a weak CYP3A4 inducer. Entrectinib inhibited P-glycoprotein (IC50 1.33 μM) but is a poor substrate. In healthy subjects, itraconazole increased entrectinib Cmax and AUC by 73% and 504%, respectively, and rifampin decreased entrectinib Cmax and AUC by 56% and 77%, respectively. Single dose entrectinib did not affect midazolam AUC, although Cmax decreased by 34%. Multiple dose entrectinib increased midazolam AUC by 50% and decreased Cmax by 21%. Single dose entrectinib increased digoxin AUC and Cmax by 18% and 28%, respectively, but did not affect digoxin renal clearance. Conclusions Entrectinib is a CYP3A4 substrate and is sensitive to the effects of coadministered moderate/strong CYP3A4 inhibitors and strong inducers, and requires dose adjustment. Entrectinib is a weak inhibitor of CYP3A4 and P-glycoprotein and no dose adjustments are required with CYP3A4/P- glycoprotein substrates.Registration Number (Study 2) NCT03330990 (first posted online November 6, 2017) As studies 1 and 3 are phase 1 trials in healthy subjects, they are not required to be registered.

The effect of grape seed and green tea extracts on the pharmacokinetics of imatinib and its main metabolite, N-desmethyl imatinib, in rats

Background Imatinib is mainly metabolized by CYP3A4 and to a lesser extent by other isoenzymes, with N-desmethyl imatinib being its major equipotent metabolite. Being a CYP3A4 substrate, imatinib co-administration with CYP3A4 modulators would change its pharmacokinetic profile. The cancer chemoprevention potential and anticancer efficacy of many herbal products such as grape seed (GS) and green tea (GT) extracts had led to an increase in their concomitant use with anticancer agents. GS and GT extracts were demonstrated to be potent inhibitors of CYP3A4. The aim of this study is to investigate the effect of standardized GS and/or GT extracts at two different doses on the pharmacokinetics of imatinib and its metabolite, N-desmethyl imatinib, in SD-rats. Methods Standardized GS and/or GT extracts were administered orally once daily for 21 days, at low (l) and high (h) doses, 50 and 100 mg/kg, respectively, before the administration of a single intragastric dose of imatinib. Plasma samples were collected and analyzed for imatinib and N-desmethyl imatinib concentrations using LC-MS/MS method, then their non-compartmental pharmacokinetic parameters were determined. Results h-GS dose significantly decreased imatinib’s Cmax and the $$ {\mathrm{AUC}}_0^{\infty } $$ AUC 0 ∞ by 61.1 and 72.2%, respectively. Similar effects on N-desmethyl imatinib’s exposure were observed as well, in addition to a significant increase in its clearance by 3.7-fold. l-GT caused a significant decrease in imatinib’s Cmax and $$ {\mathrm{AUC}}_0^{\infty } $$ AUC 0 ∞ by 53.6 and 63.5%, respectively, with more significant effects on N-desmethyl imatinib’s exposure, which exhibited a significant decrease by 79.2 and 81.1%, respectively. h-GT showed similar effects as those of l-GT on the kinetics of imatinib and its metabolite. However, when these extracts were co-administered at low doses, no significant effects were shown on the pharmacokinetics of imatinib and its metabolite. Nevertheless, increasing the dose caused a significant decrease in Cmax of N-desmethyl imatinib by 71.5%. Conclusions These results demonstrated that the pharmacokinetics of imatinib and N-desmethyl imatinib had been significantly affected by GS and/or GT extracts, which could be partially explained by the inhibition of CYP3A-mediated metabolism. However, the involvement of other kinetic pathways such as other isoenzymes, efflux and uptake transporters could be involved and should be characterized. Graphical abstract

A short exploration of selected sensitive CYP3A4 substrates (Probe Drug)

Background: CYP450 enzymes in the liver have a significant role in the metabolism of xenobiotics. Probe drug strategy is broadly used to evaluate the pharmacodynamic & pharmacokinetic Drug/ herb-drug interactions/ Fooddrug interactions. Probe drugs guarantee the exact pathway of drug metabolism in the liver by its targeted tractability property. The CYP3A4 isoenzyme metabolizes majority of the drugs (65%). Methods: The characters of targeted probe drugs were observed from admetSAR (version2) online database. Results: Midazolam is widely used as a probe drug because of its peculiar character. Midazolam, affirms the accurate and consistent prediction of pharmacokinetic mediated drug interactions even within nanogram concentrations either within sight of and without a potent CYP3A inhibitor. Remarkably midazolam is used as CYP3A4 substrate in the majority of in vivo studies. Conclusion: However, midazolam shows a good response in all clinical studies because of its lesser half-life and bioavailability when compared with other probe drugs.

Topological Analysis of Electron Density in Large Biomolecular Systems

Background: A great step toward describing the structure of the molecular electron was made in the era of quantum chemical methods. Methods play a very important role in the prediction of molecular properties and in the description of the reactivity of compounds, which cannot be overestimated. There are many works, books, and articles on quantum methods, their applications, and comparisons. At the same time, quantum methods of a high level of theory, which give the most accurate results, are time-consuming, which makes them almost impossible to describe large complex molecular systems, such as macromolecules, enzymes, supramolecular compounds, crystal fragments, and so on. Objective: To propose an approach that allows real-time estimation of electron density in large systems, such as macromolecules, nanosystems, proteins. Methods: AlteQ approach was applied to the tolopogical analysis of electron density for “substrate - cytochrome” complexes. The approach is based on the use of Slater’s type atomic contributions. Parameters of the atomic contributions were found using high resolution X-ray diffraction data for organic and inorganic molecules. Relationships of the parameters with atomic number, ionization potentials and electronegativities were determined. The sufficient quality of the molecular electron structure representation was shown under comparison of AlteQ predicted and observed electron densities. AlteQ algorithm was applied for evaluation of electron structure of “CYP3A4 – substrate” complexes modeled using BiS/MC restricted docking procedure. Topological analysis (similar to Atoms In Molecules (AIM) theory suggested by Richard F.W. Bader) of the AlteQ molecular electron density was carried out for each complex. The determination of (3,-1) bond, (3,+1) ring, (3,+3) cage critical points of electron density in the intermolecular “CYP3A4 – substrate” space was performed. Results: Different characteristics such as electron density, Laplacian eigen values, etc. at the critical points were computed. Relationship of pKM (KM is Michaelis constant) with the maximal value of the second Laplacian eigen value of electron density at the critical points and energy of complex formation computed using MM3 force field was determined. Conclusion: It was shown that significant number of (3,-1) bond critical points are located in the intermolecular space between the enzyme site and groups of substrate atoms eliminating during metabolism processes.

Peripheral neuropathy in non-Hodgkin’s lymphoma patients receiving vincristine with and without aprepitant/fosaprepitant

Background Peripheral neuropathy is a common treatment-related adverse effect associated with vincristine. Vincristine is a major CYP3A4 substrate and is often administered alongside the neurokinin-1 (NK-1) receptor antagonists, aprepitant or fosaprepitant, which are moderate CYP3A4 inhibitors. This inhibition may result in increased concentrations of vincristine and an increased incidence of toxicity. Objective The primary objective of this study was to investigate if there is a clinically significant drug interaction between vincristine and aprepitant or fosaprepitant resulting in early-onset peripheral neuropathy. The secondary objective of this study was to investigate the cumulative rate of chemotherapy-induced peripheral neuropathy (CIPN). Methodology This was a single-centered, retrospective, cohort chart review. Patients receiving vincristine-based chemotherapy between 1 July 2010 through 30 June 2018 were identified and reviewed for concomitant use of aprepitant or fosaprepitant and incidence of neuropathy. Early-onset CIPN was defined as neuropathy onset during the first cycle of chemotherapy. Results A total of 115 subjects were retrospectively reviewed over the study period, of whom 71 were included in the aprepitant/fosaprepitant group and 44 were included in the group without a NK-1 receptor antagonist. Of the subjects who received aprepitant/fosaprepitant, 26.7% experienced early-onset peripheral neuropathy as compared to 22.7% in the group without a NK-1 receptor antagonist ( P = 0.627). Overall, CIPN was higher in the group who received aprepitant/fosaprepitant compared to the group without (56% vs. 36%, P = 0.036). Conclusion There appears to be an increased risk of CIPN with the concomitant use of vincristine and aprepitant or fosaprepitant.

Biotransformation of the Mycotoxin Enniatin B1 by CYP P450 3A4 and Potential for Drug-Drug Interactions

Enniatins (ENNs) are fungal secondary metabolites that frequently occur in grain in temperate climates. Their toxic potency is connected to their ionophoric character and lipophilicity. The biotransformation of ENNs predominantly takes place via cytochrome P450 3A (CYP 3A)-dependent oxidation reactions. Possible interaction with ENNs is relevant since CYP3A4 is the main metabolic enzyme for numerous drugs and contaminants. In the present study, we have determined the kinetic characteristics and inhibitory potential of ENNB1 in human liver microsomes (HLM) and CYP3A4-containing nanodiscs (ND). We showed in both in vitro systems that ENNB1 is mainly metabolised by CYP3A4, producing at least eleven metabolites. Moreover, ENNB1 significantly decreased the hydroxylation rates of the typical CYP3A4-substrate midazolam (MDZ). Deoxynivalenol (DON), which is the most prevalent mycotoxin in grain and usually co-occurrs with the ENNs, was not metabolised by CYP3A4 or binding to its active site. Nevertheless, DON affected the efficiency of this biotransformation pathway both in HLM and ND. The metabolite formation rates of ENNB1 and the frequently used drugs progesterone (PGS) and atorvastatin (ARVS) lactone were noticeably reduced, which indicated a certain affinity of DON to the enzyme with subsequent conformational changes. Our results emphasise the importance of drug–drug interaction studies, also with regard to natural toxins.