Metabolic profiling of the anti-tumor drug regorafenib in mice

Use of Structural Alerts for Reactive Metabolites in the Application SpotRM

Reactive metabolite (RM) formation is widely accepted as playing a crucial role in causing idiosyncratic adverse drug reactions (IADRs), where the liver is most affected. An important goal of drug design is to avoid selection of drug candidates giving rise to RMs and therefore risk causing problems later on involving IADRs. The simplest, initial approach is to avoid test structures that have substructures known or strongly suspected to be associated with IADRs. However, as is evident from the many case reports of IADRs, in most cases a clear association with any (bio)chemical mechanism is lacking, which makes it hard to establish any structure-toxicity relationship. Separate studies of RM formation, in vitro and in vivo, have led to likely evidence and to establishing many structural alerts (SAs) that can be used for fast selection/deselection of planned test compounds. As a background to a discussion of the concept, 25 kinase inhibitor drugs with known problems of hepatotoxicity were probed against a set of SAs contained in the application SpotRM. A clear majority of the probed drugs show liabilities as evident by being flagged by more than one of the fairly established types of SAs. At the same time, no clear SAs were found in three drugs, which is discussed in the broader context of usefulness and selection tactics of SAs in drug design.

Species differences in oxidative metabolism of regorafenib

Despite the prevalence of laboratory animals such as monkeys, rats, and mice in clinical drug trials, we know little regarding the oxidation of regorafenib in these test subjects. This study aimed to elucidate species differences in the kinetics of regorafenib oxidation into two metabolites: regorafenib N-oxide (M-2) and hydroxyregorafenib (M-3).M-2 formation best fitted the Hill equation and showed positive cooperativity in liver and small intestinal microsomes from all species. For all species, M-2 formation had a higher maximum velocity in microsomes from the liver than the small intestines. Maximum velocity was also higher in microsomes from humans and monkeys than those from rats and mice. M-3 formation was well-fitted to the Hill equation and showed positive cooperativity in all microsomes, except those from rat small intestines, where it exhibited biphasic kinetics. At half the maximum velocity, substrate concentration for M-2 and M-3 formation was lower in microsomes from humans than from other species. Moreover, M-2 was the major metabolite in microsomes from humans, monkeys, and mice, whereas M-2 and M-3 were the major metabolites in rat microsomes.M-2 and M-3 formation involving CYP3A4 and CYP3A5 fitted to the Hill equation. However, M-3 formation involving CYP2J2 fitted to the substrate inhibition model.Our study confirmed species differences in regorafenib oxidative metabolism.

Highly sensitive detection of anti-cancer drug based on bimetallic reduced graphene oxide nanocomposite

Herein, we describe a high-performance electrochemical sensor for the detection of regorafenib (REG) using bimetallic Pd-Ru nanoparticles anchored on pomegranate peel extract (PPE) derived reduced graphene oxide (Pd-Ru/rGO). PPE was employed to neutralize the extremely acidic graphene then cast-off along with the metal precursor for the duration of the chemical reduction to accomplish well dispersed Pd-Ru nanoparticles. Bimetallic Pd-Ru/rGO nanocomposites were synthesized using a facile chemical reduction method. Under optimal conditions, based on the differential pulse voltammetric studies it has been confirmed that the fabricated sensors has good electrocatalytic activity toward the detection of REG, spanning over the linear dynamic range of 0.5-300 nM. Moreover, the sensor exhibited a low limit of detection of 1.6 nM and a limit of quantification of 4.8 nM. The electrochemical sensor unveiled admirable selectivity and sensitivity, reproducibility, and repeatability. The fabricated sensor was suitable for real sample analysis (pharmaceutical tablet, human blood plasm, wastewater) with satisfactory recovery. The strategy presented herein can be employed in the development of electrochemical sensors for other target analytes.

The impact of individual human cytochrome P450 enzymes on oxidative metabolism of anticancer drug lenvatinib

Lenvatinib, a small molecule tyrosine kinase inhibitor (TKI), exhibits good inhibitory effect in several types of carcinomas. Specifically, it is the most effective TKI used for treatment of thyroid cancer. To extend pharmacokinetics data on this anticancer agent, we aimed to identify the metabolites of lenvatinib formed during in vitro incubation of lenvatinib with human hepatic microsomes or recombinant cytochromes P450 (CYPs) by using high performance liquid chromatography and mass spectrometry. The role of CYPs in the oxidation of lenvatinib was initially investigated in hepatic microsomes using specific CYP inhibitors. CYP-catalytic activities in each microsomal sample were correlated with the amounts of lenvatinib metabolites formed by these samples. Further, human recombinant CYPs were employed in the metabolic studies. Based on our data, lenvatinib is metabolized to O-desmethyl lenvatinib, N-descyclopropyl lenvatinib and lenvatinib N-oxide. In the presence of cytochrome b₅, recombinant CYP3A4 was the most efficient to form these metabolites. In addition, CYP1A1 significantly contributes to the lenvatinib metabolism. It was even more efficient in forming of O-desmethyl lenvatinib than CYP3A4 in the absence of cytochrome b₅. The present study indicates that further research focused on drug-drug interactions, in particular on CYP3A4 and CYP1A1 modulators, is needed. This will pave new avenues towards TKIs-mediated personalized therapy.

Chemical Aspects of Human and Environmental Overload with Fluorine

Over the last 100-120 years, due to the ever-increasing importance of fluorine-containing compounds in modern technology and daily life, the explosive development of the fluorochemical industry led to an enormous increase of emission of fluoride ions into the biosphere. This made it more and more important to understand the biological activities, metabolism, degradation, and possible environmental hazards of such substances. This comprehensive and critical review focuses on the effects of fluoride ions and organofluorine compounds (mainly pharmaceuticals and agrochemicals) on human health and the environment. To give a better overview, various connected topics are also discussed: reasons and trends of the advance of fluorine-containing pharmaceuticals and agrochemicals, metabolism of fluorinated drugs, withdrawn fluorinated drugs, natural sources of organic and inorganic fluorine compounds in the environment (including the biosphere), sources of fluoride intake, and finally biomarkers of fluoride exposure.

Development of template systems for ligand interactions of CYP3A5 and CYP3A7 and their distinctions from CYP3A4 template

Starting from established CYP3A4 Template (DMPK. 2019, and 2020), CYP3A5 and CYP3A7 Templates have been constructed to be reliable tools for verification of their distinct catalytic properties. A distinct occupancy was observed on CYP3A4-selective ligands, but not on the non-selective ligands, in simulation experiments. These ligands often invade into Bay-1 region during the migration from Entrance to Site of oxidation in simulation experiments. These results offered an idea of the distinct localization of Bay-1 residue on CYP3A5 Template, in which the Bay-1 residue stayed closely to Template border. The idea also accounted for the higher oxidation rates of CYP3A5, than of CYP3A4, of noscapine and schisantherin E through their enhanced sitting-stabilization. Typical CYP3A7 substrates such as zonisamide and retinoic acids took their placements without occupying a left side region of Template for their metabolisms. In turn, the occupancies of the left-side region were inevitably observed among poor ligands of CYP3A7. Altered extent of IJK-Interaction or localization of a specific residue at the left-side would thus explain distinct catalytic properties of CYP3A7 on Template. These data suggest the alteration of each one of Template region, from CYP3A4 Template, led to the distinct catalytic properties of CYP3A5 and CYP3A7 forms.

Therapeutic Efficacy of Nyctanthes arbor-tristis Flowers to Inhibit Proliferation of Acute and Chronic Primary Human Leukemia Cells, with Adipocyte Differentiation and in Silico Analysis of Interactions between Survivin Protein and Selected Secondary Metabolites

Although the antidiabetic efficacy of Nyctanthes arbor-tristis flowers has been reported, antiproliferative and anti-obesity activities are yet to be explored. We examined the anti-obesity and antiproliferative potentials of different fractions (hexane, chloroform, ethyl acetate, methanol) of N. abor-tristis flower extract for the first time using 3T3-L1 cells, primary peripheral blood mononuclear cells (PBMC) isolated from healthy and adult acute myeloid (AML) and chronic lymphocytic leukemia (CLL) patients, recombinant Jurkat T cells, and MCF7 cell lines. The in vitro hypoglycemic activity was evaluated using the inhibition of α-amylase enzyme and glucose uptake by yeast cells. The percentage glucose uptake and α-amylase inhibitory activity increased in a dose-dependent manner in the crude and the tested fractions (hexane and ethyl acetate). Inhibition of the 3T3-L1 cells’ differentiation was observed in the ethyl acetate and chloroform fractions, followed by the hexane fraction. Antiproliferative analyses revealed that Nyctanthes exerted a high specific activity against anti-AML and anti-CLL PBMC cells, especially by the hexane and ethyl acetate fractions. The gas chromatography/mass spectrometry analysis indicated the presence of 1-heptacosanol (hexane fraction), 1-octadecene (hexane and chloroform fractions), and other organic compounds. Molecular docking demonstrated that phenol,2,5-bis(1,1-dimethylethyl) and 4-hydroxypyridine 1-oxide compounds showed specificity toward survivin protein, indicating the feasibility of N. abor-tristis in developing new drug leads against leukemia.

Metabolic profiling of tyrosine kinase inhibitor nintedanib using metabolomics

Nintedanib is a promising tyrosine kinase inhibitor for clinically treating idiopathic pulmonary fibrosis (IPF). Some clinical cases reported that nintedanib treatment can cause hepatotoxicity and myocardial toxicity. U. S. FDA warns the potential drug-drug interaction when it is co-administrated with other drugs. In order to understand the potential toxicity of nintedanib and avoid drug-drug interaction, the metabolism of nintedanib was systematically investigated in human liver microsomes and mice using metabolomics approach, and the toxicity of metabolites was predicted by ADMET lab. Nineteen metabolites were detected in vivo and in vitro metabolism, and 8 of them were undescribed. Calculated partition coefficients (Clog P) were used to distinguish the isomers of nintedanib metabolites in this study. The major metabolic pathways of nintedanib majorly included hydroxylation, demethylation, glucuronidation, and acetylation reactions. The ADMET prediction indicated that nintedanib was a substrate of the cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp). And nintedanib and most of its metabolites might possess potential hepatotoxicity and cardiotoxicity. This study provided a global view of nintedanib metabolism, which could be used to understand the mechanism of adverse effects related to nintedanib and its potential drug-drug interaction.

Metabolic Activation of Elemicin Leads to the Inhibition of Stearoyl-CoA Desaturase 1

Elemicin is a constituent of natural aromatic phenylpropanoids present in many herbs and spices. However, its potential to cause toxicity remains unclear. To examine the potential toxicity and associated mechanism, elemicin was administered to mice for 3 weeks and serum metabolites were examined. Enlarged livers were observed in elemicin-treated mice, which were accompanied by lower ratios of unsaturated- and saturated-lysophosphatidylcholines in plasma, and inhibition of stearoyl-CoA desaturase 1 (Scd1) mRNA expression in liver. Administration of the unsaturated fatty acid oleic acid reduced the toxicity of 1'-hydroxylelemicin, the primary oxidative metabolite of elemicin, while treatment with the SCD1 inhibitor A939572 potentiated its toxicity. Furthermore, the in vitro use of recombinant human CYPs and chemical inhibition of CYPs in human liver microsomes revealed that CYP1A1 and CYP1A2 were the primary CYPs responsible for elemicin bioactivation. Notably, the CYP1A2 inhibitor α-naphthoflavone could attenuate the susceptibility of mice to elemicin-induced hepatomegaly. This study revealed that metabolic activation of elemicin leads to SCD1 inhibition in liver, suggesting that upregulation of SCD1 may serve as potential intervention strategy for elemicin-induced toxicity.

Interaction between phytotherapy and oral anticancer agents: prospective study and literature review

Cancer is becoming more prevalent in elderly patient. Due to polypharmacy, older adults with cancer are predisposed to drug-drug interactions. There is also an increasing interest in the use of complementary and alternative medicine (CAM). Thirty to seventy percent of patients with cancer have used CAM. Through pharmaceutical counseling sessions, we can provide advices on herb-drug interactions (HDI). All the patients seen in pharmaceutical counseling sessions were prospectively included. Information was collected during these sessions: prescribed medication (oral anticancer agents (OAA) and other drugs), CAM (phytotherapy especially), and use of over-the-counter (OTC) drugs. If pharmacist considered an interaction or an intervention clinically relevant, the oncologist was notified. Then, a literature review was realized to identify the potential HDI (no interactions, precautions for use, contraindication). Among 201 pharmacist counseling sessions, it resulted in 104 interventions related to 46 HDI, 28 drug-drug interactions and 30 others (wrong dosage, omission…). To determine HDI, we review 73 medicinal plants which are used by our patients with cancer and 31 OAA. A total of 1829 recommendations were formulated about 59 (75%) medical plants and their interaction with an OAA. Herb-drug interactions should not be ignored by healthcare providers in their management of cancer patients in daily practice.

Interaction Between Sex and Organic Anion-Transporting Polypeptide 1b2 on the Pharmacokinetics of Regorafenib and Its Metabolites Regorafenib-N-Oxide and Regorafenib-Glucuronide in Mice

Regorafenib, a multikinase inhibitor used in the treatment of various solid tumors, undergoes extensive uridine 5′‐diphosphate glucuronosyltransferase (Ugt)1a9‐mediated glucuronidation to form regorafenib‐N‐β‐glucuronide (M7; RG), but the contribution of hepatic uptake transporters, such as organic anion‐transporting polypeptide (Oatp)1b2, to the pharmacokinetics of regorafenib remains poorly understood. Using NONMEM‐based, population‐based, parent‐metabolite modeling, we found that Oatp1b2 and sex strongly impact the systemic exposure to RG in mice receiving oral regorafenib. Metabolic studies revealed that the liver microsomal expression of cytochrome P450 (Cyp)3a11 is twofold lower in female mice, whereas Ugt1a9 levels and function are not sex dependent. This finding is consistent with the metabolism of regorafenib occurring via two competing pathways, and the lack of Oatp1b2 results in decreased clearance of RG. The described model provides mechanistic insights into the in vivo disposition of regorafenib.

The multikinase inhibitor regorafenib decreases angiogenesis and improves portal hypertension

Background and Aims

Angiogenesis is critically involved in the development of liver fibrosis, portal hypertension (PHT) and hepatocellular carcinoma (HCC). Regorafenib is a novel second-line therapy for HCC, but might also be beneficial in fibrosis and PHT even in absence of HCC. This study investigated the effects of regorafenib in experimental models without HCC.

Methods

Fibrosis (in vivo and in vitro), inflammation, liver damage (aminotransferases), angiogenesis (matrigel implantation) and in vivo systemic and portal hemodynamics were assessed in different mouse and rat models (bile duct ligation, CCl₄, partial portal vein ligation) after acute and chronic treatment with regorafenib.

Results

Long-term treatment with regorafenib improved portal hypertension most likely due to blunted angiogenesis, without affecting fibrosis progression or regression. Interestingly, acute administration of regorafenib also ameliorated portal hemodynamics. Although regorafenib treatment led to hepatotoxic side effects in long-term treated fibrotic animals, in partial portal vein ligated rats, no liver toxicity due to regorafenib was observed.

Discussion

Regorafenib might be especially suitable as therapy in patients with PHT and preserved liver function.