Differential metabolism of gefitinib and erlotinib by human cytochrome P450 enzymes

Gefitinib-Induced Severe Dermatological Adverse Reactions: A Case Report and Pharmacogenetic Profile

Gefitinib is a selective inhibitor of the epidermal growth factor receptor that is used to treat advanced and metastatic non-small cell lung cancer (NSCLC). Dermatological adverse reactions are most commonly associated with gefitinib treatment. The cause of adverse reactions in individuals is multifactorial. Pharmacogenetics is an effective tool to detect such adverse reactions. This case report describes a female patient with NSCLC who was administered gefitinib at a dose of 250 mg/day. However, due to severe adverse dermatological reactions, the treatment was interrupted for 15 d and antibiotic therapy was administered to manage the skin rashes, maculopapular rashes, and hyperpigmentation. Treatment adherence was adequate, and no drug interactions were detected. A pharmacogenetic analysis revealed homozygosity in the ATP-binding cassette (ABC)-B1 rs1128503 (c.1236A>G), heterozygosity in ABCG2 rs2231142 (c.421G>T) and rs2622604 (c.-20+614T>C), and a non-functional variant of the cytochrome P450 family 3, subfamily A, member 5 (CYP3A5). The relationship between altered genetic variants and the presence of adverse reactions induced by gefitinib is still controversial. Overall, this case report highlights the importance of continuing to study pharmacogenetics as predictors of adverse drug reactions.

Detection of pharmacolipidodynamic effects following the intravenous and oral administration of gefitinib to C57Bl/6JRj mice by rapid UHPLC-MS analysis of plasma

Omics-based biomarker technologies, including metabolic profiling (metabolomics/metabonomics) and lipidomics, are making a significant impact on disease understanding, drug development, and translational research. A wide range of patho-physiological processes involve lipids and monitoring changes in lipid abundance can give valuable insights into mechanisms of drug action, off target pharmacology and toxicity. Here we report changes, detected by untargeted LC-MS, in the plasma lipid profiles of male C57Bl/6JRj mice following the PO and IV administration of the epidermal growth factor receptor (EGFR) inhibitor gefitinib. Statistical analysis of the data obtained for both the IV and PO samples showed time-related changes in the amounts of lipids from several different classes. The largest effects were associated with a rapid onset of these changes following gefitinib administration followed by a gradual return by 24 h post dose to the type of lipid profile seen in predose samples. Investigation of the lipids responsible for the variance observed in the data showed that the PI, PC, LPC, PE and TG were subject to the largest disruption with both transient increases and decreases in relative amounts seen in response to administration of the drug. The pattern of the changes in the relative abundances of those lipids subject to variation appeared to be correlated to the pharmacokinetics of gefitinib (and its major metabolites). These observations support the concept of a distinct pharmacolipidodynamic relationship between drug exposure and plasma lipid abundance.

Humanization of SLCO2B1 in Rats Increases rCYP3A1 Protein Expression but Not the Metabolism of Erlotinib to OSI-420

The organic anion transporting polypeptide (OATP)2B1 [(gene: solute carrier organic anion transporter family member 2B1 (SLCO2B1)] is an uptake transporter that facilitates cellular accumulation of its substrates. Comparison of SLCO2B1+/+ knockin and rSlco2b1-/- knockout rats showed a higher expression of rCYP3A1 in the humanized animals. We hypothesize that humanization of OATP2B1 not only affects cellular uptake but also metabolic activity. To further investigate this hypothesis, we used SLCO2B1+/+ and rSlco2b1-/ - rats and the OATP2B1 and rCYP3A1 substrate erlotinib, which is metabolized to OSI-420, for in vivo and ex vivo experiments. One hour after administration of a single dose of erlotinib, the knockin rats exhibited significantly lower erlotinib serum levels, but no change was observed in metabolite concentration or the OSI-420/erlotinib ratio. Similar results were obtained for liver tissue levels comparing SLCO2B1+/+ and rSlco2b1-/- rats. Liver microsomes isolated from the erlotinib-treated animals were characterized ex vivo for rCYP3A activity using testosterone, showing higher activity in the knockin rats. The contrary was observed when microsomes isolated from treatment-naïve animals were assessed for the metabolism of erlotinib to OSI-420. The latter is in contrast to the higher rCYP3A1 protein amount observed by western blot analysis in rat liver lysates and liver microsomes isolated from untreated rats. In summary, rats humanized for OATP2B1 showed higher expression of rCYP3A1 in liver and reduced serum levels of erlotinib but no change in the OSI-420/erlotinib ratio despite a lower OSI-420 formation in isolated liver microsomes. Studies with CYP3A-specific substrates are warranted to evaluate whether humanization affects not only rCYP3A1 expression but also metabolic activity in vivo. SIGNIFICANCE STATEMENT: Humanization of rats for the organic anion transporting polypeptide (OATP)2B1 increases rCYP3A1 expression and activity in liver. Using the OATP2B1/CYP3A-substrate erlotinib to assess the resulting phenotype, we observed lower erlotinib serum and liver concentrations but no impact on the liver/serum ratio. Moreover, there was no difference in the OSI-420/erlotinib ratio comparing humanized and knockout rats, suggesting that OSI-420 is not applicable to monitor differences in rCYP3A1 expression as supported by data from ex vivo experiments with rat liver microsomes.

Dermatologic toxicities in epidermal growth factor receptor: a comprehensive pharmacovigilance study from 2013 to 2023

Epidermal growth factor receptor inhibitors (EGFRIs) induced cutaneous toxicity is a common adverse event (AE), although it is not as severe as major cancers, we still need to pay enough attention to them. Therefore, it is necessary to evaluate the diversity of EGFRI class drugs. The objective of this study was to conduct a scientific and systematic investigation into the correlation between EGFRI and cutaneous toxicities. The data accessed from the FDA adverse event reporting system database (FAERS) encompass a time frame spanning from January 2013 to March 2023. By utilizing reporting odds ratios (RORs), information components (ICs), proportional reporting ratios (PRRs), and chi-squared (χ2), the relationship between drugs and adverse reactions was evaluated through disproportionality analysis. Within the FAERS database, a total of 29,559 skin adverse events were recorded. A robust indication of the correlation between EGFRI and elderly patients (≥65 years) was identified. Among EGFRIs, erlotinib accounted for the largest proportion of skin adverse events (39.72%). Rash, dry skin, and pruritus ranked top among all preferred terms, and signals such as rash, skin lesions, and acneiform dermatitis were detected in every single drug. Clinicians should guide patients customize the treatment plan for each patient.

CYP1A inhibitors: Recent progress, current challenges, and future perspectives

Mammalian cytochrome P450 1A (CYP1A) are key phase I xenobiotic-metabolizing enzymes that play a distinctive role in metabolic activation or metabolic clearance of a variety of procarcinogens, drugs, and endogenous substances. Human CYP1A subfamily contains two members (hCYP1A1 and hCYP1A2), which are known to catalyze the oxidative activation of some environmental procarcinogens into carcinogenic species. Increasing evidence has demonstrated that CYP1A inhibitor therapies are promising strategies for cancer chemoprevention or overcoming CYP1A-associated drug toxicity and resistance. Herein, we reviewed recent advances in the discovery and characterization of hCYP1A inhibitors, from the discovery approaches to structural features and biomedical applications of hCYP1A inhibitors. The inhibition potentials, inhibition modes, and inhibition constants of all reported hCYP1A inhibitors are comprehensively summarized. Meanwhile, the structural features and structure-activity relationships of different classes of hCYP1A1 and hCYP1A2 inhibitors are analyzed and discussed in depth. Furthermore, the major challenges and future directions for this field are presented and highlighted. Collectively, the information and knowledge presented here will strongly facilitate the researchers to discover and develop more efficacious CYP1A inhibitors for specific purposes, such as chemo-preventive agents or as tool molecules in hCYP1A-related fundamental studies.

Effect of genetic polymorphisms on the pharmacokinetics of gefitinib in healthy Chinese volunteers

Gefitinib is the first-generation drug of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) metabolised by the cytochrome P450 and transported by P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2). In the present study, the pharmacokinetics of gefitinib in healthy Chinese volunteers was investigated and the effect of genetic polymorphisms on its variability was evaluted.Forty-five healthy volunteers were administered a single dose of gefitinib and the blood samples were used for quantifying the concentration of gefitinib and genotyping fifteen single-nucleotide polymorphisms of cytochrome P450 enzymes (CYP3A4, CYP3A5, CYP2D6, CYP2C9 and CYP2C19) and drug transporters (ABCB1 and ABCG2).CYP3A5*3 (rs776746) polymorphism showed a significant influence, with higher gefitinib AUC0-t in carrier of CC genotype than in CT/TT genotype (BH-adjusted p value <0.05). For CYP2C9*3 (rs1057910), significant differences in pharmacokinetics of gefitinib were detected between carriers of AA and AC genotypes, with higher AUC0-t, AUC0-∞ and Cmax in carrier of AC genotype than in AA gen-otype (BH-adjusted p value <0.05). No associations were found between SNPs in CYP3A4, CYP2D6, CYP2C19, ABCB1, ABCG2 and the pharmacokinetics of gefitinib.The SNPs in CYP3A5*3 (rs776746) and CYP2C9*3 (rs1057910) were found to be associated with altered gefitinib pharmacokinetics in healthy Chinese volunteers.

Simultaneous quantification of atorvastatin, erlotinib and OSI-420 in rat serum and liver microsomes using a novel liquid chromatography-mass spectrometry method

Erlotinib is an epidermal growth factor receptor tyrosine kinase inhibitor used in the treatment of cancer. Atorvastatin is a statin commonly applied to treat hypercholesterolemia. In humans, both compounds are metabolized by CYP3A4 and are transported by OATP2B1, ABCB1 and ABCG2. We aimed to generate and validate a bioanalytical method for simultaneous determination of atorvastatin, erlotinib and its major metabolite OSI-420 applicable to biological samples. Quantification of erlotinib, OSI-420, and atorvastatin was achieved with an Agilent high-performance liquid chromatography system 1100/1200 coupled to a triple quadrupole G6410B. The method involved separation over the column Kinetex C8 (100 × 3 mm, 2.6 µm) using 2 mM ammonium acetate (pH 4.0) and acetonitrile as eluent. The method was assessed for selectivity, accuracy, recovery, matrix effect, and stability over a range from 1 to 4,000 ng/mL according to the respective guidelines. We applied the bioanalytical method to quantify the formation of OSI-420 in liver microsomes isolated from male and female Wistar rats. The optimized experiment revealed slower formation in microsomes of female compared to male rats, in which we observed lower amounts of CYP3A1 by Western blot analysis. Moreover, the presence of atorvastatin inhibited the CYP3A-mediated metabolism of erlotinib. Serum obtained from a drug-drug interaction study performed in male rats was also analyzed using the validated method. Non-compartmental pharmacokinetic analysis revealed a lower clearance of erlotinib when atorvastatin was co-administered. However, for atorvastatin we observed a lower systemic exposure in presence of erlotinib. In summary, we report a method to detect OSI-420, erlotinib and atorvastatin applicable to samples from ex vivo and in vivo studies.

Pharmacokinetics, safety, tolerability, and feasibility of apatinib in combination with gefitinib in stage IIIB-IV EGFR-mutated non-squamous NSCLC: a drug-drug interaction study

PURPOSE

Apatinib combined with gefitinib was proven to benefit advanced EGFR-mutant NSCLC patients in first-line treatment. This study aimed to evaluate the drug-drug interaction of gefitinib and apatinib when coadministered in EGFR-mutated NSCLC patients.

METHODS

In this phase 1b, multi-center, open-label, fixed-sequence study, the drug-drug interaction of gefitinib and apatinib was evaluated when coadministered in EGFR-mutated NSCLC patients. Patients received single-agent apatinib 500 mg QD on days 1-4. Gefitinib 250 mg QD was given on days 5-15 and combined with apatinib 500 mg QD on days 12-15. Serial blood samples were drawn on days 4 and 15. The plasma concentrations and other pharmacokinetics parameters were measured for apatinib with and without gefitinib.

RESULTS

The study enrolled 22 patients and 20 were analyzed for pharmacokinetics. There were no distinct differences in apatinib Cmax and AUC0-τ with versus without gefitinib (geometric LSM ratio, 0.96 [90% CI 0.84-1.10] for Cmax and 1.12 [90% CI 0.96-1.30] for AUC0-τ). Similar PFS and grade of treatment-emergent adverse events (TEAEs) were found between different Cmax and AUC0-τ of apatinib and gefitinib at 500 mg apatinib and 250 mg gefitinib dose levels.

CONCLUSIONS

Apatinib pharmacokinetics parameters were not significantly changed when coadministered with gefitinib. All TEAEs were manageable, and there was no need to change the dose level when combining apatinib and gefitinib (ClinicalTrials.gov identifier: NCT04390984, May 18, 2020).

Novel Approaches to Characterize Individual Drug Metabolism and Advance Precision Medicine

Interindividual variability in drug metabolism can significantly affect drug concentrations in the body and subsequent drug response. Understanding an individual's drug metabolism capacity is important for predicting drug exposure and developing precision medicine strategies. The goal of precision medicine is to individualize drug treatment for patients to maximize efficacy and minimize drug toxicity. While advances in pharmacogenomics have improved our understanding of how genetic variations in drug-metabolizing enzymes (DMEs) affect drug response, nongenetic factors are also known to influence drug metabolism phenotypes. This minireview discusses approaches beyond pharmacogenetic testing to phenotype DMEs-particularly the cytochrome P450 enzymes-in clinical settings. Several phenotyping approaches have been proposed: traditional approaches include phenotyping with exogenous probe substrates and the use of endogenous biomarkers; newer approaches include evaluating circulating noncoding RNAs and liquid biopsy-derived markers relevant to DME expression and function. The goals of this minireview are to 1) provide a high-level overview of traditional and novel approaches to phenotype individual drug metabolism capacity, 2) describe how these approaches are being applied or can be applied to pharmacokinetic studies, and 3) discuss perspectives on future opportunities to advance precision medicine in diverse populations. SIGNIFICANCE STATEMENT: This minireview provides an overview of recent advances in approaches to characterize individual drug metabolism phenotypes in clinical settings. It highlights the integration of existing pharmacokinetic biomarkers with novel approaches; also discussed are current challenges and existing knowledge gaps. The article concludes with perspectives on the future deployment of a liquid biopsy-informed physiologically based pharmacokinetic strategy for patient characterization and precision dosing.

Cellular photo(geno)toxicity of gefitinib after biotransformation

Gefitinib (GFT) is a selective epidermal growth factor receptor (EGFR) inhibitor clinically used for the treatment of patients with non-small cell lung cancer. Bioactivation by mainly Phase I hepatic metabolism leads to chemically reactive metabolites such as O-Demethyl gefitinib (DMT-GFT), 4-Defluoro-4-hydroxy gefitinib (DF-GFT), and O-Demorpholinopropyl gefitinib (DMOR-GFT), which display an enhanced UV-light absorption. In this context, the aim of the present study is to investigate the capability of gefitinib metabolites to induce photosensitivity disorders and to elucidate the involved mechanisms. According to the neutral red uptake (NRU) phototoxicity test, only DF-GFT metabolite can be considered non-phototoxic to cells with a photoirritation factor (PIF) close to 1. Moreover, DMOR-GFT is markedly more phototoxic than the parent drug (PIF = 48), whereas DMT-GFT is much less phototoxic (PIF = 7). Using the thiobarbituric acid reactive substances (TBARS) method as an indicator of lipid photoperoxidation, only DMOR-GFT has demonstrated the ability to photosensitize this process, resulting in a significant amount of TBARS (similar to ketoprofen, which was used as the positive control). Protein photooxidation monitored by 2,4-dinitrophenylhydrazine (DNPH) derivatization method is mainly mediated by GFT and, to a lesser extent, by DMOR-GFT; in contrast, protein oxidation associated with DMT-GFT is nearly negligible. Interestingly, the damage to cellular DNA as revealed by the comet assay, indicates that DMT-GFT has the highest photogenotoxic potential; moreover, the DNA damage induced by this metabolite is hardly repaired by the cells after a time recovery of 18 h. This could ultimately result in mutagenic and carcinogenic effects. These results could aid oncologists when prescribing TKIs to cancer patients and, thus, establish the conditions of use and recommend photoprotection guidelines.

OregonFluor enables quantitative intracellular paired agent imaging to assess drug target availability in live cells and tissues

Non-destructive fluorophore diffusion across cell membranes to provide an unbiased fluorescence intensity readout is critical for quantitative imaging applications in live cells and tissues. Commercially available small-molecule fluorophores have been engineered for biological compatibility, imparting high water solubility by modifying rhodamine and cyanine dye scaffolds with multiple sulfonate groups. The resulting net negative charge, however, often renders these fluorophores cell-membrane-impermeant. Here we report the design and development of our biologically compatible, water-soluble and cell-membrane-permeable fluorophores, termed OregonFluor (ORFluor). By adapting previously established ratiometric imaging methodology using bio-affinity agents, it is now possible to use small-molecule ORFluor-labelled therapeutic inhibitors to quantitatively visualize their intracellular distribution and protein target-specific binding, providing a chemical toolkit for quantifying drug target availability in live cells and tissues.

PEGylated Erlotinib HCl Injectable Nanoformulation for Improved Bioavailability

The present study was undertaken to synthesize PEGylated monomethoxy poly (ethylene glycol)-poly (ε-Caprolactone) (mPEG-PCL) block copolymer and formulate Erlotinib HCl-loaded mPEG-PCL nanoparticles for enhancing the bioavailability of the drug. Using the ring-opening polymerization technique, PEGylated mPEG-PCL block copolymer was synthesized, and the structure of the copolymer was characterized using FTIR, ¹H-NMR, and DSC techniques. The solvent evaporation approach was used to effectively encapsulate Erlotinib HCl within block copolymeric nanoparticles. Erlotinib HCl-loaded mPEG-PCL nanoparticles had a mean particle size of 146.5 ± 2.37 nm and a zeta potential of -27.8 ± 2.77 mV. The nanoparticles had a percent entrapment efficiency of 80.78 ± 0.09%. The in vitro drug release of Erlotinib HCl-loaded copolymeric nanoparticles showed a slow and sustained release behavior which could be maintained for up to 72 h. The Korsmeyer-Peppas fitting findings indicated that the drug release process followed a non-Fickian diffusion mechanism. The pharmacokinetic (PK) behavior of the developed nanoformulation was studied in albino Wistar rats, and the relative bioavailability of the optimized NP formulation given by intravenous route was found to be 187.33%. The PK data suggested that Erlotinib HCl-loaded mPEG-PCL copolymeric nanoparticles can dramatically alter the PK behavior of Erlotinib HCl and greatly improve the drug's bioavailability by as much as three times when compared to the oral formulation. As a result, it was established that the block copolymeric nanoparticles have promise for the effective encapsulation of Erlotinib HCL for an injectable formulation with increased bioavailability.

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients

The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.

Gefitinib conjugated PEG passivated graphene quantum dots incorporated PLA microspheres for targeted anticancer drug delivery

In the present study, polyethylene Glycol passivated Graphene Quantum Dots (PEG-GQDs) were successfully synthesized via the hydrothermal method. Furthermore, for the synthesis of anticancer drug loaded GQD embedded microspheres, the anticancer drug was mixed with synthesized PEG-GQD. As prepared, Gefitinib-PEG-GQDs were incorporated into poly-lactic acid (PLA) microspheres using poly-vinyl-acetate (PVA) as surfactant via solvent evaporation technique and single emulsification method. The successful synthesis of anticancer drug loaded microspheres was confirmed by several characterization techniques, including Field-Emission Scanning Electron Microscopy (FE-SEM), which shows the morphology of microspheres, Fourier Transform Infrared Spectroscopy (FTIR) analysis gives an idea about functional group present in the microspheres. X-ray diffraction (XRD) provides information about the crystallinity of the samples respectively. The drug release characteristics were determined by UV-Vis spectrophotometric analysis. Moreover, the in-vitro cell-based cytotoxicity assay indicated almost insignificant cytotoxicity of the NCI-H522 cell line (Human, Lung, Non-small cell lung cancer).

Evaluation of factors affecting epidermal growth factor receptor tyrosine kinase inhibitor-induced hepatotoxicity in Japanese patients with non-small cell lung cancer: a two-center retrospective study

Background

Gefitinib and erlotinib, are epidermal growth factor receptor tyrosine kinase inhibitors, and are currently recommended for non-small cell lung cancer stage IV in the elderly and in patients with decreased performance status in the Japanese Lung Cancer Society Guideline, but they occasionally caused severe hepatotoxicity requiring postponement or modification of treatment. However, little is known about the risk factors for hepatotoxicity in patients receiving gefitinib and erlotinib. In this study, we investigated the factors influencing hepatotoxicity in Japanese non-small cell lung cancer (NSCLC) patients treated with gefitinib or erlotinib monotherapy.

Methods

Japanese patients with NSCLC who started gefitinib or erlotinib monotherapy from January 2005 to December 2017 at Kanazawa University Hospital or Kanazawa Medical University Hospital were included in this study. Factors affecting hepatotoxicity were retrospectively investigated by multiple logistic regression analysis.

Results

A total of 102 patients who received gefitinib and 95 patients who received erlotinib were included in the analysis. In the gefitinib group, a body mass index (BMI) ≥ 25 was associated with an increased risk of hepatotoxicity (OR = 4.571, 95% CI = 1.486–14.056, P = 0.008). In the erlotinib group, concomitant use of acid-suppressing medications (AS), namely proton pump inhibitors or histamine-2 receptor antagonists, was associated with a reduced risk of hepatotoxicity (OR = 0.341, 95% CI = 0.129–0.900, P = 0.030).

Conclusions

BMI ≥ 25 in patients treated with gefitinib increased the risk of hepatotoxicity. In contrast, AS combination with erlotinib reduced the risk of hepatotoxicity. Thus, because different factors influence the risk of hepatotoxicity, monitoring for adverse events should take into account patient background factors and concomitant medications.

Effects of p450 Polymorphisms on the Clinical Outcomes of Gefitinib Treatment in Patients with Epidermal Growth Factor Receptor Mutation-Positive Non-Small Cell Lung Cancer

Aims: In this study, we determined whether different genotypes of drug-metabolizing enzymes are associated with the therapeutic effects of gefitinib in non-small cell lung cancer (NSCLC). Methods: A retrospective analysis of 112 patients with stage III or IV NSCLC was performed. The clinical characteristics of these patients, including progression-free survival (PFS), outcome of gefitinib treatment, and relationship between the genotypes of rs1065852/rs2242480 and prognosis, were analyzed. Results: The rs1065852 CT/TT genotype was associated with worse prognosis than the CC type (p = 0.0306), and the median PFS was lower than that with the CC type (287 days vs. 350 days). Compared with those with CC+CC genotypes, individuals carrying T alleles (CT/TT+CT/TT) at rs1065852/rs2242480 had a poorer prognosis, and the median PFS of CT/TT+CT/TT at rs1065852/rs2242480 was significantly lower than that of the CC+CC type (188 days vs. 444.5 days). Conclusions: Genotypes of the drug-metabolizing enzymes rs1065852 and rs2242480 have an impact on the prognosis of patients with NSCLC treated with gefitinib.

MHADTI: predicting drug-target interactions via multiview heterogeneous information network embedding with hierarchical attention mechanisms

MOTIVATION

Discovering the drug-target interactions (DTIs) is a crucial step in drug development such as the identification of drug side effects and drug repositioning. Since identifying DTIs by web-biological experiments is time-consuming and costly, many computational-based approaches have been proposed and have become an efficient manner to infer the potential interactions. Although extensive effort is invested to solve this task, the prediction accuracy still needs to be improved. More especially, heterogeneous network-based approaches do not fully consider the complex structure and rich semantic information in these heterogeneous networks. Therefore, it is still a challenge to predict DTIs efficiently.

RESULTS

In this study, we develop a novel method via Multiview heterogeneous information network embedding with Hierarchical Attention mechanisms to discover potential Drug-Target Interactions (MHADTI). Firstly, MHADTI constructs different similarity networks for drugs and targets by utilizing their multisource information. Combined with the known DTI network, three drug-target heterogeneous information networks (HINs) with different views are established. Secondly, MHADTI learns embeddings of drugs and targets from multiview HINs with hierarchical attention mechanisms, which include the node-level, semantic-level and graph-level attentions. Lastly, MHADTI employs the multilayer perceptron to predict DTIs with the learned deep feature representations. The hierarchical attention mechanisms could fully consider the importance of nodes, meta-paths and graphs in learning the feature representations of drugs and targets, which makes their embeddings more comprehensively. Extensive experimental results demonstrate that MHADTI performs better than other SOTA prediction models. Moreover, analysis of prediction results for some interested drugs and targets further indicates that MHADTI has advantages in discovering DTIs.

AVAILABILITY AND IMPLEMENTATION

https://github.com/pxystudy/MHADTI.

Clinical outcomes of gefitinib and erlotinib in patients with NSCLC harboring uncommon EGFR mutations: A pooled analysis of 438 patients

BACKGROUND

The purpose of this study was to investigate the outcomes of gefitinib and erlotinib in patients with non-small cell lung cancer (NSCLC) with uncommon epidermal growth factor receptor (EGFR) mutations.

METHODS

Relevant researches were identified by a literature search of the PubMed database. Patients with EGFR mutations other than exon 19 deletion and L858R were eligible for the study. Clinical outcomes included objective response rate (ORR), progression free survival (PFS), and overall survival (OS). We categorized all uncommon EGFR mutations as: single uncommon EGFR mutations and compound mutations that containing 2 or more kinds of EGFR mutations. We also assessed outcomes in patients categorized by EGFR-TKIs: (1) gefitinib group; (2) erlotinib group.

RESULTS

A total of 438 patients with NSCLC harboring uncommon EGFR mutations were included in this study. The ORR for gefitinib and erlotinib was 43.8 %, with a median PFS (mPFS) of 6.00 months and a median OS (mOS) of 20.50 months. Patients with compound mutations had an ORR of 56.3 % and an mPFS of 8.10 months. Both of them were significantly better than these in patients with single uncommon EGFR mutation, which were 29.3 % and 3.90 months, respectively (odds ratio (ORa): 2.74, 95 % confidence interval (CI): 1.86-4.05, P < 0.001; hazard ratio (HR): 0.58, 95 % CI: 0.48-0.71, P < 0.001). Moreover, patients with compound mutations containing 19 deletion or L858R had a superior response and survival benefits compared to patients with other compound mutation patterns. In addition, the gefitinib group showed a favorable efficacy advantage (P = 0.003) and PFS benefit (P = 0.021) compared to the erlotinib group.

CONCLUSIONS

Uncommon EGFR mutations exhibit favorable but inconsistent treatment responses and survival outcomes to gefitinib and erlotinib, which are closely related to the mutation pattern, the cooccurring partner mutant genes, and the type of EGFR-TKIs received.

Mechanistic Modeling of Central Nervous System Pharmacokinetics and Target Engagement of HER2 Tyrosine Kinase Inhibitors to Inform Treatment of Breast Cancer Brain Metastases

PURPOSE

This study evaluated the central nervous system (CNS) pharmacokinetics and target engagement of lapatinib, neratinib, and tucatinib in patients with cancer, using a physiologically based pharmacokinetic (PBPK) modeling approach.

EXPERIMENTAL DESIGN

Drug-specific parameters for in vitro metabolism, binding to plasma proteins and brain tissues, transcellular passive permeability, and interactions with efflux transporters were determined. Whole-body PBPK models integrated with a 4-compartment permeability-limited brain model was developed and verified for predicting plasma and CNS pharmacokinetics. Target engagement ratio (TER), defined as the ratio of the average steady-state unbound drug brain concentration (Css,ave,br) to in vitro IC50 for HER2 inhibition, was used as a predictor of intracranial efficacy.

RESULTS

PBPK models predicted that following 1 cycle of standard dosing, tucatinib and lapatinib achieved similar Css,ave,br (14.5 vs. 16.8 nmol/L), while neratinib Css,ave,br (0.68 nmol/L) was 20-fold lower. Tucatinib and neratinib were equally potent for HER2 inhibition (IC50, 6.9 vs. 5.6 nmol/L), while lapatinib was less potent (IC50, 109 nmol/L). The model-predicted population mean TER in the human normal brain was 2.1 for tucatinib, but < 0.20 for lapatinib and neratinib.

CONCLUSIONS

The PBPK modeling suggests that tucatinib induces sufficient HER2 inhibition (TER > 2.0) in not only brain metastases with a disrupted blood-brain barrier (BBB), but also micrometastases where the BBB largely remains intact. These findings, in line with available clinical pharmacokinetics and efficacy data, support the therapeutic value of tucatinib for treatment of brain metastases and warrant further clinical investigation for the prevention of brain metastases in patients with HER2-positive breast cancer.

The Development of Positron Emission Tomography Tracers for In Vivo Targeting the Kinase Domain of the Epidermal Growth Factor Receptor

Multiple small molecule PET tracers have been developed for the imaging of the epidermal growth factor receptor (EGFR). These tracers target the tyrosine kinase (TK) domain of the receptor and have been used for both quantifying EGFR expression and to differentiate between EGFR mutational statuses. However, the approaches for in vivo evaluation of these tracers are diverse and have resulted in data that are hard to compare. In this review, we analyze the historical development of the in vivo evaluation approaches, starting from the first EGFR TK PET tracer [11C]PD153035 to tracers developed based on TK inhibitors used for the clinical treatment of mutated EGFR expressing non-small cell lung cancer like [11C]erlotinib and [18F]afatinib. The evaluation of each tracer has been compiled to allow for a comparison between studies and ultimately between tracers. The main challenges for each group of tracers are thereafter discussed. Finally, this review addresses the challenges that need to be overcome to be able to efficiently drive EGFR PET imaging forward.

Potent Inhibition of Human Cytochrome P450 3A4 by Biflavone Components from Ginkgo Biloba and Selaginella Tamariscina

CYP3A4-mediated Phase I biotransformation is the rate-limiting step of elimination for many commonly used clinically agents. The modulatory effects of herbal medicines on CYP3A4 activity are one of the risk factors affecting the safe use of drug and herbal medicine. In the present study, the inhibitory effects of nearly hundred kinds of herbal medicines against CYP3A4 were evaluated based on a visual high-throughput screening method. Furthermore, biflavone components including bilobetin (7-demethylginkgetin, DGK), ginkgetin (GK), isoginkgetin (IGK), and amentoflavone (AMF) were identified as the main inhibitory components of Ginkgo biloba L. (GB) and Selaginella tamariscina (P. Beauv.) Spring (ST), which displayed very strong inhibitory effects toward CYP3A4. The inhibitory effects of these biflavones on clinical drugs that mainly undergo CYP3A4-dependent metabolism were evaluated. The IC₅₀ of GK toward tamoxifen, gefitinib and ticagrelor were found to be of 0.478 ± 0.003, 0.869 ± 0.001, and 1.61 ± 0.039 μM, respectively. These results suggest the potential pharmacokinetic interactions between the identified biflavones and clinical drugs undergoing CYP3A4-mediated biotransformation. The obtained information is important for guiding the rational use of herbal medicine in combination with synthetic pharmaceuticals.

Integration of liquid biopsy and pharmacogenomics for precision therapy of EGFR mutant and resistant lung cancers

The advent of molecular profiling has revolutionized the treatment of lung cancer by comprehensively delineating the genomic landscape of the epidermal growth factor receptor (EGFR) gene. Drug resistance caused by EGFR mutations and genetic polymorphisms of drug metabolizing enzymes and transporters impedes effective treatment of EGFR mutant and resistant lung cancer. This review appraises current literature, opportunities, and challenges associated with liquid biopsy and pharmacogenomic (PGx) testing as precision therapy tools in the management of EGFR mutant and resistant lung cancers. Liquid biopsy could play a potential role in selection of precise tyrosine kinase inhibitor (TKI) therapies during different phases of lung cancer treatment. This selection will be based on the driver EGFR mutational status, as well as monitoring the development of potential EGFR mutations arising during or after TKIs treatment, since some of these new mutations may be druggable targets for alternative TKIs. Several studies have identified the utility of liquid biopsy in the identification of EGFR driver and acquired resistance with good sensitivities for various blood-based biomarkers. With a plethora of sequencing technologies and platforms available currently, further evaluations using randomized controlled trials (RCTs) in multicentric, multiethnic and larger patient cohorts could enable optimization of liquid-based assays for the detection of EGFR mutations, and support testing of CYP450 enzymes and drug transporter polymorphisms to guide precise dosing of EGFR TKIs.

The Effect of Hepatic Impairment on the Pharmacokinetics of Dacomitinib

Background and Objective

Dacomitinib is a kinase inhibitor indicated for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR)-activating mutations. To evaluate the effect of hepatic impairment on the pharmacokinetics of dacomitinib, two dedicated studies were conducted to inform optimal dosing.

Methods

Study 1 (NCT01571388) evaluated the effect of mild and moderate hepatic impairment on the plasma pharmacokinetics, safety, and tolerability after a single oral dose of dacomitinib 30 mg, and Study 2 (NCT03865446) evaluated the same endpoints in a severe hepatic impairment population. Both studies were phase I, open-label, parallel-group studies. A one-way analysis of variance (ANOVA) with unequal variance assumption and hepatic impairment group as a fixed effect was used to compare the natural log of area under the plasma concentration-time curve extrapolated to infinite time (AUC_inf), AUC from time zero to the last quantifiable concentration (AUC_last), and maximum plasma concentration (C_max) for each hepatic impairment group to the respective normal hepatic function group. Since dacomitinib is a cytochrome P450 (CYP) 2D6 substrate, only participants with extensive or intermediate CYP2D6 phenotypes were included in the primary analysis.

Results

The AUC_inf for participants with mild, moderate, or severe hepatic impairment decreased by 6%, decreased by 23%, and increased by 4%, respectively, compared with normal hepatic function, while the C_max for participants with mild, moderate, or severe hepatic impairment increased by 3%, decreased by 20%, and increased by 31%, respectively, compared with normal hepatic function. A single oral dose of dacomitinib 30 mg was well tolerated in all participants.

Conclusion

Based on these pharmacokinetic results, dacomitinib pharmacokinetics of participants with mild, moderate, or severe hepatic impairment were not statistically different relative to participants with normal hepatic function based on the ANOVA analysis. No dacomitinib dose adjustments for patients with hepatic impairment are recommended.

Clinical Trial Registration

ClinicalTrials.gov NCT01571388, registered 5 April 2012; ClinicalTrials.gov NCT03865446, registered 6 March 2019.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-022-01125-x.

CCN2 Binds to Tubular Epithelial Cells in the Kidney

Cellular communication network-2 (CCN2), also called connective tissue growth factor (CTGF), is considered a fibrotic biomarker and has been suggested as a potential therapeutic target for kidney pathologies. CCN2 is a matricellular protein with four distinct structural modules that can exert a dual function as a matricellular protein and as a growth factor. Previous experiments using surface plasmon resonance and cultured renal cells have demonstrated that the C-terminal module of CCN2 (CCN2(IV)) interacts with the epidermal growth factor receptor (EGFR). Moreover, CCN2(IV) activates proinflammatory and profibrotic responses in the mouse kidney. The aim of this paper was to locate the in vivo cellular CCN2/EGFR binding sites in the kidney. To this aim, the C-terminal module CCN2(IV) was labeled with a fluorophore (Cy5), and two different administration routes were employed. Both intraperitoneal and direct intra-renal injection of Cy5-CCN2(IV) in mice demonstrated that CCN2(IV) preferentially binds to the tubular epithelial cells, while no signal was detected in glomeruli. Moreover, co-localization of Cy5-CCN2(IV) binding and activated EGFR was found in tubules. In cultured tubular epithelial cells, live-cell confocal microscopy experiments showed that EGFR gene silencing blocked Cy5-CCN2(IV) binding to tubuloepithelial cells. These data clearly show the existence of CCN2/EGFR binding sites in the kidney, mainly in tubular epithelial cells. In conclusion, these studies show that circulating CCN2(IV) can directly bind and activate tubular cells, supporting the role of CCN2 as a growth factor involved in kidney damage progression.

Pre-clinical drug-drug interactions (DDIs) of gefitinib with/without losartan and selective serotonin reuptake inhibitors (SSRIs): citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, and venlafaxine

Objective

Methods

Results

Conclusion

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In vitro hepatocytes assays can predict relevant drug-drug interactions (DDIs).

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Proof-of concept data testing can provide a clear insight of multidrug regimen DDIs.

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Classifying drugs as inhibitors/inducers alone cannot successfully identify DDIs.

•

Regimens requiring three or more drugs may cause significant DDIs (p-value < 0.05).

•

SSRI metabolism by human hepatocytes can be affected by gefitinib and losartan.

Severe adverse cutaneous reactions induced by gefitinib combined with antihypertensive and antihyperlipidemic drugs in lung cancer: a case report

The incidence of lung cancer is increasing yearly worldwide, and targeted medicines are the main choice for lung cancer patients. However, there has been no relevant research about the analysis and adjustment of drug combinations for cancer patients with hypertension and hyperlipidemia until now. Here, we reported a case of medicine adjustment for a patient of lung cancer with hypertension and hyperlipidemia. The patient was diagnosed as right lung adenocarcinoma with lymph node metastasis and continued taking gefitinib tablets to maintain therapeutic efficacy after the end of chemotherapy. Severe paronychia and a high plasma concentration of gefitinib were noticed when the patient visited the hospital for reexamination. The clinical pharmacist found that the patient took nifedipine sustained-release tablets and simvastatin tablets simultaneously, and these medicines were all substrates of CYP3A4. The clinical pharmacist suggested replacing the medicines for hypertension and hyperlipidemia with valsartan capsules (Diovan) and rosuvastatin calcium tablets (Crestor), respectively. The adverse cutaneous reactions were greatly relieved, and the plasma concentration of gefitinib was decreased when another reexamination was performed. Therapeutic drug monitoring was an important method in our case and provided valuable information to develop individualized treatment strategies. For cancer patients suffering from other diseases such as hypertension and hyperlipidemia, it is necessary to pay special attention to the drug-drug interactions and metabolic pathways among drug combinations.

Inter-ethnic differences in pharmacokinetics-is there more that unites than divides?

Inter-ethnic variability in pharmacokinetics (PK) has been attributed to several factors ranging from genetic to environmental. It is not clear how current teaching in higher education (HE) reflects what published literature suggests on this subject. This study aims to gain insights into current knowledge about inter-ethnic differences in PK based on reports from published literature and current teaching practices in HE. A systematic literature search was conducted on PubMed and Scopus to identify suitable literature to be reviewed. Insights into inter-ethnic differences in PK teaching among educators in HE and industry were determined using a questionnaire. Thirty-one percent of the studies reviewed reported inter-ethnic differences in PK, of these, 37% of authors suggested genetic polymorphism as possible explanation for the inter-ethnic differences observed. Other factors authors proposed included diet and weight differences between ethnicities. Most respondents (80%) who taught inter-ethnic difference in PK attributed inter-ethnic differences to genetic polymorphism. While genetic polymorphism is one source of variability in PK, the teaching of genetic polymorphism is better associated with interindividual variabilities rather than inter-ethnic differences in PK as there are no genes with PK implications specific to any one ethnic group. Nongenetic factors such as diet, weight, and environmental factors, should be highlighted as potential sources of interindividual variation in the PK of drugs.

Globally Approved EGFR Inhibitors: Insights into Their Syntheses, Target Kinases, Biological Activities, Receptor Interactions, and Metabolism

Targeting the EGFR with small-molecule inhibitors is a confirmed valid strategy in cancer therapy. Since the FDA approval of the first EGFR-TKI, erlotinib, great efforts have been devoted to the discovery of new potent inhibitors. Until now, fourteen EGFR small-molecule inhibitors have been globally approved for the treatment of different types of cancers. Although these drugs showed high efficacy in cancer therapy, EGFR mutations have emerged as a big challenge for these drugs. In this review, we focus on the EGFR small-molecule inhibitors that have been approved for clinical uses in cancer therapy. These drugs are classified based on their chemical structures, target kinases, and pharmacological uses. The synthetic routes of these drugs are also discussed. The crystal structures of these drugs with their target kinases are also summarized and their bonding modes and interactions are visualized. Based on their binding interactions with the EGFR, these drugs are also classified into reversible and irreversible inhibitors. The cytotoxicity of these drugs against different types of cancer cell lines is also summarized. In addition, the proposed metabolic pathways and metabolites of the fourteen drugs are discussed, with a primary focus on the active and reactive metabolites. Taken together, this review highlights the syntheses, target kinases, crystal structures, binding interactions, cytotoxicity, and metabolism of the fourteen globally approved EGFR inhibitors. These data should greatly help in the design of new EGFR inhibitors.

Inhibition of 6-formylindolo[3,2-b]carbazole metabolism sensitizes keratinocytes to UVA-induced apoptosis: Implications for vemurafenib-induced phototoxicity

Ultraviolet (UV) B irradiation of keratinocytes results in the formation of the tryptophan photoproduct 6-formylindolo[3,2-b]carbazole (FICZ) which is a high-affinity ligand for the aryl hydrocarbon receptor (AHR). The resulting activation of AHR signaling induces the expression of cytochrome P450 (CYP) 1A1 which subsequently metabolizes FICZ. Importantly, FICZ is also a nanomolar photosensitizer for UVA radiation. Here, we assess whether a manipulation of the AHR-CYP1A1 axis in human epidermal keratinocytes affects FICZ/UVA-induced phototoxic effects and whether this interaction might be mechanistically relevant for the phototoxicity of the BRAF inhibitor vemurafenib. Treatment of keratinocytes with an AHR agonist enhanced the CYP1A1-catalyzed metabolism of FICZ and thus prevented UVA photosensitization, whereas an inhibition of either AHR signaling or CYP1A1 enzyme activity resulted in an accumulation of FICZ and a sensitization to UVA-induced oxidative stress and apoptosis. Exposure of keratinocytes to vemurafenib resulted in the same outcome. Specifically, CYP phenotyping revealed that vemurafenib is primarily metabolized by CYP1A1 and to a lesser degree by CYP2J2 and CYP3A4. Hence, vemurafenib sensitized keratinocytes to UVA-induced apoptosis by interfering with the CYP1A1-mediated oxidative metabolism of FICZ. In contrast to this pro-apoptotic effect, a treatment of UVB-damaged keratinocytes with vemurafenib suppressed apoptosis, a process which might contribute to the skin carcinogenicity of the drug. Our results provide insight into the mechanisms responsible for the photosensitizing properties of vemurafenib and deliver novel information about its metabolism which might be relevant regarding potential drug-drug interactions. The data emphasize that the AHR-CYP1A1 axis contributes to the pathogenesis of cutaneous adverse drug reactions.

PXR Modulates the Prostate Cancer Cell Response to Afatinib by Regulating the Expression of the Monocarboxylate Transporter SLC16A1

Simple Summary

Many kinase inhibitors have been tested as potential alternatives for the treatment of castration-resistant prostate cancers. However, none of these clinical trials led to drug approval despite interesting responses. Our study reveals that genes involved in drug metabolism and their master regulator PXR (Pregnane X Receptor) could be responsible, at least in part, for these disappointing results as they can modulate tumor cell response to specific kinase inhibitors. We found that stable expression of PXR sensitized prostate cancer cells to erlotinib, dabrafenib, and afatinib, while it rendered cells resistant to dasatinib and had no effect for other inhibitors tested. We also report for the first time that sensitization to afatinib is due to an alteration in drug transport that involves the SLC16A1 monocarboxylate transporter. Together, our results further indicate that PXR might be considered as a biomarker of response to kinase inhibitors in castration-resistant prostate cancers.

Abstract

Resistance to castration is a crucial issue in the treatment of metastatic prostate cancer. Kinase inhibitors (KIs) have been tested as potential alternatives, but none of them are approved yet. KIs are subject of extensive metabolism at both the hepatic and the tumor level. Here, we studied the role of PXR (Pregnane X Receptor), a master regulator of metabolism, in the resistance to KIs in a prostate cancer setting. We confirmed that PXR is expressed in prostate tumors and is more frequently detected in advanced forms of the disease. We showed that stable expression of PXR in 22Rv1 prostate cancer cells conferred a resistance to dasatinib and a higher sensitivity to erlotinib, dabrafenib, and afatinib. Higher sensitivity to afatinib was due to a ~ 2-fold increase in its intracellular accumulation and involved the SLC16A1 transporter as its pharmacological inhibition by BAY-8002 suppressed sensitization of 22Rv1 cells to afatinib and was accompanied with reduced intracellular concentration of the drug. We found that PXR could bind to the SLC16A1 promoter and induced its transcription in the presence of PXR agonists. Together, our results suggest that PXR could be a biomarker of response to kinase inhibitors in castration-resistant prostate cancers.

The Pharmacometabodynamics of Gefitinib after Intravenous Administration to Mice: A Preliminary UPLC-IM-MS Study

The effects of intravenous gefitinib (10 mg/kg), an anilinoquinazoline thymidylate kinase inhibitor (TKI), selective for the epidermal growth factor receptor (EGFR), on the urinary metabotypes of mice were studied. We hypothesized that, in response to the administration of gefitinib, there might be significant changes in the excretion of many endogenous metabolites in the urine, which could be correlated with the plasma pharmacokinetics (PK) of the drug. In order to investigate this conjecture, urine from male C57 BL6 mice was collected before IV dosing (10 mg/kg) and at 0–3, 3–8, and 8–24 h post-dose. The samples were profiled by UPLC/IM/MS and compared with the profiles obtained from undosed control mice with the data analyzed using multivariate statistical analysis (MVA). This process identified changes in endogenous metabolites over time and these were compared with drug and drug metabolite PK and excretion. While the MVA of these UPLC/IM/MS data did indeed reveal time-related changes for endogenous metabolites that appeared to be linked to drug administration, this analysis did not highlight the presence of either the drug or its metabolites in urine. Endogenous metabolites affected by gefitinib administration were identified by comparison of mass spectral, retention time and ion mobility-derived collision cross section data (compared to authentic standards wherever possible). The changes in endogenous metabolites resulting from gefitinib administration showed both increases (e.g., tryptophan, taurocholic acid, and the dipeptide lysyl-arginine) and decreases (e.g., deoxyguanosine, 8-hydroxydeoxyguanosine, and asparaginyl-histidine) relative to the control animals. By 8–24 h, the post-dose concentrations of most metabolites had returned to near control values. From these studies, we conclude that changes in the amounts of endogenous metabolites excreted in the urine mirrored, to some extent, the plasma pharmacokinetics of the drug. This phenomenon is similar to pharmacodynamics, where the pharmacological effects are related to the drug concentrations, and by analogy, we have termed this effect “pharmacometabodynamics”.

Pre-clinical drug-drug interaction (DDI) of gefitinib or erlotinib with Cytochrome P450 (CYP) inhibiting drugs, fluoxetine and/or losartan

•

In vitro drug-drug interactions (DDIs) can predict drug combination outcomes.

•

Cytochrome (CYP) P450 and hepatocytes are able to confirm DDIs.

•

Fluoxetine inhibited CYP metabolism of gefitinib and erlotinib in supersomes.

•

Hepatocyte metabolism tested here was unaffected by fluoxetine or losartan alone.

•

A regimen containing three or more drugs may cause an unexpected DDI (p ≤ 0.05).

Objective

To evaluate drug-drug interactions (DDIs) between gefitinib or erlotinib with fluoxetine, and/or losartan.

Methods

Human pooled microsomes, supersomes, and cryopreserved human hepatocytes were used to monitor DDIs in vitro. RED (Rapid Equilibrium Dialysis) protein binding was employed to investigate other pharmacokinetics.

Results

Gefitinib is significantly metabolized by Cytochrome P450 (CYP) 2D6 and CYP3A4, with less than 80% of the drug remaining. Erlotinib is significantly metabolized by CYP3A4, CYP2D6, and CYP1A2. Although gefitinib and erlotinib were metabolized by the same CYP isoenzymes, the metabolites formed from degradation of the two drugs were different.

Fluoxetine inhibited CYP2D6 and CYP3A4 metabolism of gefitinib with an IC₅₀ of 65.12 ± 1.88 µM and 4.11 ± 2.26 µM, respectively. Fluoxetine also inhibited CYP2D6 and CYP3A4 metabolism of erlotinib with an IC₅₀ of 7.06 ± 1.54 µM and 4.57 ± 1.22 µM, respectively.

For hepatocytes, fluoxetine affected the metabolism of gefitinib or erlotinib, while losartan had no effect. Gefitinib and erlotinib inhibited the metabolism of fluoxetine and losartan. Two-drug combinations involving gefitinib or erlotinib with fluoxetine or losartan yielded insignificant (p-value ≥ 0.05) differences in metabolism. However, combinations involving three drugs yielded significant degrees of inhibition (p-value ≤ 0.05). Three drug combinations involving fluoxetine and losartan with gefitinib or erlotinib yielded significant degrees of inhibition of the metabolism of gefitinib, but not for that of erlotinib.

Conclusion

As could be predicted by previous studies involving the inhibitory effect of fluoxetine on CYP3A4 and CYP2D6, and studies involving CYP metabolism of gefitinib and erlotinib, the tests performed here confirmed that fluoxetine has an inhibitory effect on metabolism of gefitinib or erlotinib by the main CYP isoenzymes involved. This study suggests a variable inhibitory effect of fluoxetine particularly on CYP2D6 activity towards gefitinib or erlotinib; erlotinib metabolism is less affected. Likewise, the combination of fluoxetine and losartan does not significantly affect hepatocyte metabolism of erlotinib, but does for that of gefitinib. The results presented in this study thus indicate a need for DDI assays to involve multiple drugs to properly study multidrug regimens.

The Pharmacokinetics of Gefitinib in a Chinese Cancer Population Group: A Virtual Clinical Trials Population Study

Gefitinib, a selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, is used to treat non-small-cell lung cancer (NSCLC). Lung cancer rates are high in China and are expected to increase over the next decade. CYP 2D6 intermediate metaboliser (IM) phenotypes are more prevalent in the Chinese population compared to Caucasians; the increased risk of drug-drug interactions (DDI) with chemotherapy polypharmacy may lead to different clinical pharmacokinetics outcomes for Chinese patients. This study developed and validated a virtual Chinese cancer population for the pragmatic assessment of gefitinib DDI as a victim drug in Chinese and Caucasian cancer populations. When assessing the impact of 2D6 phenotypes on bupropion mediated CYP 2D6 DDI in Chinese cancer population, we found that AUC increased by at least 60% in extensive metabolizers (EM) and 30% in IM. As a result, fmCYP2D6 was reduced by 15% in IM in the presence of bupropion, translating into > 70% of EM subjects and > 48% of IM subjects with trough concentrations at steady state (Ctrough,ss) below the gefitinib target trough level. The PBPK model predicted that a 500 mg once daily dose in both EM and IM subjects successfully reduced the percent of subjects below the Ctrough,ss. Such changes in Ctrough,ss warrant further investigation and highlight the ability of pharmacokinetic modelling to investigate populations that may be difficult to recruit for traditional clinical studies.

Metabolism and Interspecies Variation of IMMH-010, a Programmed Cell Death Ligand 1 Inhibitor Prodrug

IMMH-010 is an ester prodrug of YPD-29B, a potent programmed cell death ligand 1 (PD-L1) inhibitor. The metabolism of IMMH-010 was investigated and compared in various species. Four metabolites of IMMH-010 were identified, and the major metabolite was the parent compound, YPD-29B, which was mainly catalyzed by carboxylesterase 1 (CES1). We observed IMMH-010 metabolism in the plasma of various species. IMMH-010 was rapidly metabolized to YPD-29B in rat and mouse plasma, whereas it remained stable in human and monkey plasma. In the liver S9 fractions of human, monkey, dog, and rat, IMMH-010 was quickly transformed to YPD-29B with no obvious differences among species. In addition, the transformation ratio of IMMH-010 to YPD-29B was low in rat and human intestines, which indicated that the intestine was not an important site for IMMH-010 hydrolysis. Moreover, we demonstrated the remarkable antitumor efficacy of IMMH-010 in B16F10 melanoma and MC38 colon carcinoma xenograft mouse models. We also compared the pharmacokinetic profiles of IMMH-010 in rodents and primates. After oral administration of IMMH-010, the general exposure of active metabolite YPD-29B was slightly lower in primates than in rodents, suggesting that data should be extrapolated cautiously from rodents to humans.

Single-cell transcriptional changes associated with drug tolerance and response to combination therapies in cancer

Tyrosine kinase inhibitors were found to be clinically effective for treatment of patients with certain subsets of cancers carrying somatic mutations in receptor tyrosine kinases. However, the duration of clinical response is often limited, and patients ultimately develop drug resistance. Here, we use single-cell RNA sequencing to demonstrate the existence of multiple cancer cell subpopulations within cell lines, xenograft tumors and patient tumors. These subpopulations exhibit epigenetic changes and differential therapeutic sensitivity. Recurrently overrepresented ontologies in genes that are differentially expressed between drug tolerant cell populations and drug sensitive cells include epithelial-to-mesenchymal transition, epithelium development, vesicle mediated transport, drug metabolism and cholesterol homeostasis. We show analysis of identified markers using the LINCS database to predict and functionally validate small molecules that target selected drug tolerant cell populations. In combination with EGFR inhibitors, crizotinib inhibits the emergence of a defined subset of EGFR inhibitor-tolerant clones. In this study, we describe the spectrum of changes associated with drug tolerance and inhibition of specific tolerant cell subpopulations with combination agents.

Precision Oncology, Signaling and Anticancer Agents in Cancer Therapeutics

BACKGROUND

The global alliance for genomics and healthcare facilities provides innovational solutions to expedite research and clinical practices for complex and incurable health conditions. Precision oncology is an emerging field explicitly tailored to facilitate cancer diagnosis, prevention and treatment based on patients' genetic profile. Advancements in "omics" techniques, next-generation sequencing, artificial intelligence and clinical trial designs provide a platform for assessing the efficacy and safety of combination therapies and diagnostic procedures.

METHOD

Data were collected from Pubmed and Google scholar using keywords: "Precision medicine", "precision medicine and cancer", "anticancer agents in precision medicine" and reviewed comprehensively.

RESULTS

Personalized therapeutics including immunotherapy, cancer vaccines, serve as a groundbreaking solution for cancer treatment. Herein, we take a measurable view of precision therapies and novel diagnostic approaches targeting cancer treatment. The contemporary applications of precision medicine have also been described along with various hurdles identified in the successful establishment of precision therapeutics.

CONCLUSION

This review highlights the key breakthroughs related to immunotherapies, targeted anticancer agents, and target interventions related to cancer signaling mechanisms. The success story of this field in context to drug resistance, safety, patient survival and in improving quality of life is yet to be elucidated. We conclude that, in the near future, the field of individualized treatments may truly revolutionize the nature of cancer patient care.

Bioanalysis of erlotinib, its O-demethylated metabolites OSI-413 and OSI-420, and other metabolites by liquid chromatography-tandem mass spectrometry with additional ion mobility identification

Erlotinib is a first-generation epithelial growth factor receptor inhibitor used in the treatment of non-small cellular lung cancers. Our previously published method on a Thermo TSQ Quantum Ultra triple quadrupole mass spectrometer for the quantitation of erlotinib, OSI-420, and OSI-413 and some other kinase inhibitors was transferred to a more sensitive Sciex QTRAP5500 system. Both methods showed comparable performance in the previous range (5-5000 and 1-1000 ng/mL for erlotinib and OSI-420) with comparable accuracies and precisions (98.9-106.2 vs 98.7.0-104.0, and 3.7-13.4 vs 4.6-13.2), and a high level of agreement between the methods (R² = 0.9984 and 0.9951) for the quality control samples. The new system however was also capable of quantifying lower concentrations of both erlotinib and OSI-420 (0.5 and 0.1 ng/mL) with sufficient accuracy and precision. Along with the increased sensitivity we included the semi-quantitative determination of additional erlotinib metabolites M2, M3, M5, M6, M7, M8, M9, M10, M11, M12, M16 (hydroxy-erlotinib), M17, M18, M19, M20, M21 in a 0.1-1000 ng/mL range to the method. With a simple crash, dilute, and shoot sample preparation with acetonitrile and a 4.5 min analytical run time the method outperformed most other published methods in speed and simplicity and was suitable for TDM. Further, enhancement of the understanding of the pharmacokinetics of erlotinib and its metabolites was demonstrated.

Mechanism of hepatotoxicity of first-line tyrosine kinase inhibitors: Gefitinib and afatinib

AIMS

Both gefitinib and afatinib are epidermal growth factor tyrosine kinase inhibitors (EGFR-TKI) in the treatment of non-small cell lung cancer (NSCLC). It has been reported that gefitinib and afatinib could cause hepatotoxicity during the clinic treatment, therefore it is critical to investigate their hepatotoxicity systematically. In this study, zebrafish (Danio rerio) were used as model animals to compare the hepatotoxicity and their toxic mechanism.

MAIN METHODS

The zebrafish transgenic line [Tg (fabp10a: dsRed; ela3l:EGFP) was used in this study. After larvae developed at 3 days post fertilization (dpf), they were put into different concentrations of gefitinib and afatinib. At 6 dpf, the viability, liver area, fluorescence intensity, histopathology, apoptosis, transaminase reflecting liver function, the absorption of yolk sac, and the expression of relative genes were observed and analyzed respectively.

KEY FINDINGS

Both gefitinib and afatinib could induce the larvae hepatotoxicity dose-dependently. Based on the liver morphology, histopathology, apoptosis and function assessments, gefitinib showed higher toxicity, causing more serious liver damage. Both gefitinib and afatinib caused abnormal expressions of genes related to endoplasmic reticulum stress (ERS) pathway and apoptosis. For example, jnk, perk, bip, chop, ire1, bid, caspase3 and caspase9 were up-regulated, while xbp1s, grp78, bcl-2/bax, and caspase8 were down-regulated. The hepatotoxicity difference of gefitinib and afatinib might be due to the different expression level of related genes.

Rapid determination of the pharmacokinetics and metabolic fate of gefitinib in the mouse using a combination of UPLC/MS/MS, UPLC/QToF/MS, and ion mobility (IM)-enabled UPLC/QToF/MS

The metabolism and pharmacokinetics of gefitinib (Iressa^®, N-(3-chloro-4-fluorophenyl)-7-methoxy-6-(3-morpholino-propoxy)quinazolin-4-amine), a selective thymidylate kinase inhibitor for the epidermal growth factor receptor (EGFR), was studied after IV and PO administration to male C57BL6 mice at 10 and 50 mg/kg respectively.The pharmacokinetics and metabolism of gefitinib were investigated using a range of rapid UHPLC-MS and UHPLC-IM-HRMS methods, using both reversed-phase (RP) and hydrophilic interaction liquid chromatography (HILIC), to rapidly determine the drugs pharmacokinetics and metabolic fate.Rapid oral absorption resulted in peak plasma concentrations at 1 h of ca. 7 µg/mL, that declined with a half-life of 3.8 h (2.6 h for the IV route), and providing an estimated oral bioavailability of 53%. Gefitinib itself was the major circulating drug-related compound in plasma extracts, with a total of 11 metabolites identified.The urinary profiles determined using both HILIC and RP-UPLC-IM-MS detected gefitinib and 10 metabolites or 15 metabolites respectively including the detection of a number of novel glucuronide conjugates.Despite rapid, sub 5 min, LC profiling methods being employed metabolite coverage was shown to be high and compared well with that of previous studies.

Molecular modeling approaches to address drug-metabolizing enzymes (DMEs) mediated chemoresistance: a review

Resistance against clinically approved anticancer drugs is the main roadblock in cancer treatment. Drug metabolizing enzymes (DMEs) that are capable of metabolizing a variety of xenobiotic get overexpressed in malignant cells, therefore, catalyzing drug inactivation. As evident from the literature reports, the levels of DMEs increase in cancer cells that ultimately lead to drug inactivation followed by drug resistance. To puzzle out this issue, several strategies inclusive of analog designing, prodrug designing, and inhibitor designing have been forged. On that front, the implementation of computational tools can be considered a fascinating approach to address the problem of chemoresistance. Various research groups have adopted different molecular modeling tools for the investigation of DMEs mediated toxicity problems. However, the utilization of these in-silico tools in maneuvering the DME mediated chemoresistance is least considered and yet to be explored. These tools can be employed in the designing of such chemotherapeutic agents that are devoid of the resistance problem. The current review canvasses various molecular modeling approaches that can be implemented to address this issue. Special focus was laid on the development of specific inhibitors of DMEs. Additionally, the strategies to bypass the DMEs mediated drug metabolism were also contemplated in this report that includes analogs and pro-drugs designing. Different strategies discussed in the review will be beneficial in designing novel chemotherapeutic agents that depreciate the resistance problem.

Identification of Enzymes Oxidizing the Tyrosine Kinase Inhibitor Cabozantinib: Cabozantinib Is Predominantly Oxidized by CYP3A4 and Its Oxidation Is Stimulated by cyt b5 Activity

Herein, the in vitro metabolism of tyrosine kinase inhibitor cabozantinib, the drug used for the treatment of metastatic medullary thyroid cancer and advanced renal cell carcinoma, was studied using hepatic microsomal samples of different human donors, human recombinant cytochromes P450 (CYPs), flavin-containing mono-oxygenases (FMOs) and aldehyde oxidase. After incubation with human microsomes, three metabolites, namely cabozantinib N-oxide, desmethyl cabozantinib and monohydroxy cabozantinib, were detected. Significant correlations were found between CYP3A4 activity and generation of all metabolites. The privileged role of CYP3A4 was further confirmed by examining the effect of CYP inhibitors and by human recombinant enzymes. Only four of all tested human recombinant cytochrome P450 were able to oxidize cabozantinib, and CYP3A4 exhibited the most efficient activity. Importantly, cytochrome b₅ (cyt b₅) stimulates the CYP3A4-catalyzed formation of cabozantinib metabolites. In addition, cyt b₅ also stimulates the activity of CYP3A5, whereas two other enzymes, CYP1A1 and 1B1, were not affected by cyt b₅. Since CYP3A4 exhibits high expression in the human liver and was found to be the most efficient enzyme in cabozantinib oxidation, we examined the kinetics of this oxidation. The present study provides substantial insights into the metabolism of cabozantinib and brings novel findings related to cabozantinib pharmacokinetics towards possible utilization in personalized medicine.

Exacerbation of gefitinib-induced liver injury by glutathione reduction in mice

Gefitinib (GEF) is the first selective tyrosine kinase inhibitor of epidermal growth factor receptor. It is associated with the occurrence of clinical drug-induced liver injury. Although GEF is metabolized to chemically reactive metabolites by cytochrome P450 3A and 1A enzymes and then conjugated to glutathione (GSH), whether these reactive metabolites contribute to GEF-induced toxicity remains unknown. In this study, we investigated whether GSH depletion can sensitize mice to liver injury caused by GEF. Male C57BL/6J mice were intraperitoneally pretreated with L-buthionine (S,R)-sulfoximine (BSO) at 700 mg/kg to inhibit GSH synthesis and then orally administered GEF at 500 mg/kg every 24 hr for 4 consecutive days. The coadministration of BSO and GEF increased plasma alanine aminotransferase (ALT) levels to approximately 700 U/L and 1600 U/L at 72 and 96 hr after the first administration, respectively, whereas the increase in plasma ALT levels in mice receiving GEF at 500 mg/kg alone was limited, suggesting that GSH plays a protective role in GEF-induced liver injury. Histological examination showed nuclear karyorrhexis and sporadic single hepatocyte death in the livers of BSO+GEF coadministered mice. In these mice, the hepatic expression levels of heme oxygenase 1 (Hmox1) and metallothionein 2 (Mt2) mRNA, caspase 3/7 enzymatic activity, and the amounts of 2-thiobarbiuric acid reactive substances were significantly increased, suggesting the presence of oxidative stress, which may be associated with hepatocellular death. Together, these results show that oxidative stress as well as the reactive metabolites of GEF are involved in GEF-induced liver injury in GSH-depleted mice.

Flavoured water consumption alters pharmacokinetic parameters and increases exposure of erlotinib and gefitinib in a preclinical study using Wistar rats

Background

Erlotinib (ERL) and Gefitinib (GEF) are considered first line therapy for the management of non-small cell lung carcinoma (NSCLC). Like other tyrosine kinase inhibitors (TKIs), ERL and GEF are mainly metabolized by the cytochrome P450 (CYP450) CYP3A4 isoform and are substrates for transporter proteins with marked inter-/intra-individual pharmacokinetic (PK) variability. Therefore, ERL and GEF are candidates for drug-drug and food-drug interactions with a consequent effect on drug exposure and/or drug-related toxicities. In recent years, the consumption of flavoured water (FW) has gained in popularity. Among multiple ingredients, fruit extracts, which might constitute bioactive flavonoids, can possess an inhibitory effect on the CYP450 enzymes or transporter proteins. Therefore, in this study we investigated the effects of different types of FW on the PK parameters of ERL and GEF in Wistar rats.

Methods

ERL and GEF PK parameters in different groups of rats after four weeks consumption of different flavours of FW, namely berry, peach, lime, and pineapple, were determined from plasma drug concentrations using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

Results

Data indicated that tested FWs altered the PK parameters of both ERL and GEF differently. Lime water had the highest impact on most of ERL and GEF PK parameters, with a significant increase in C_max (95% for ERL, 58% for GEF), AUC_0-48 (111% for ERL, 203% for GEF), and AUC_0-∞ (200% for ERL, 203% for GEF), along with a significant decrease in the apparent oral clearance of both drugs (65% for ERL, 67% for GEF). The order by which FW affected the PK parameters for ERL and GEF was as follows: lime > pineapple > berry > peach.

Conclusion

The present study indicates that drinking FW could be of significance in rats receiving ERL or GEF. Our results indicate that the alteration in PKs was mostly recorded with lime, resulting in an enhanced bioavailability, and reduced apparent oral clearance of the drugs. Peach FW had a minimum effect on the PK parameters of ERL and no significant effect on GEF PKs. Accordingly, it might be of clinical importance to evaluate the PK parameters of ERL and GEF in human subjects who consume FW while receiving therapy.

Next Generation Sequencing of Advanced Non-Small Cell Lung Cancer: Utilization Based on Race and Impact on Survival

BACKGROUND

Next generation sequencing (NGS) of tumor of patients with advanced non-small cell lung cancer (NSCLC) is now a standard of care that informs the clinician on the best therapeutic approach for their patients. The purpose of our study was to investigate the overall impact of NGS testing on survival as well as potential racial differences in utilization, therapeutic decision, and genomic alterations.

METHOD

Using a large institutional database, 928 patients with stage IV NSCLC were identified. NGS testing using Foundation One platform was used. Clinical and genomic characteristics were compared by race. We used a propensity-modeling technique to compare groups that were sequenced or not in terms of overall survival. Time to event data was analyzed using Kaplan-Meier method and Cox model.

RESULTS

A total of 295 patients underwent NGS. Patients undergoing NGS testing had significantly longer survival of 25.3 months versus those who did not undergo sequencing with a median survival of 14.6 months (P = .002) irrespective if they received targeted therapy or not. There was no difference in terms of NGS utilization based on race (P = .32). African American individuals had significantly higher rates of ALK rearrangements and mutations in PBRM1, SETD2, TSC2, and FBXW7.

CONCLUSION

Our study demonstrates that within a large single institution there is no racial difference in NGS utilization and that NGS testing directly impacts survival. We identify a number of differences in genomic findings between African American and white individuals.

Polymorphisms of Drug-Metabolizing Enzymes and Transporters Contribute to the Individual Variations of Erlotinib Steady State Trough Concentration, Treatment Outcomes, and Adverse Reactions in Epidermal Growth Factor Receptor-Mutated Non-Small Cell Lung Cancer Patients

Background

Erlotinib is presently the first line treatment for non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) active mutation. An increasing number of evidences show that the treatment efficacy and toxicities are considerably heterogeneous among individuals. Hence, it is necessary to find biological predictors for further individualized treatment of erlotinib in NSCLC patients.

Methods

Our present study enrolled 87 cases of NSCLC patients who had been administrated erlotinib with a fixed dose (150 mg/d). Eleven polymorphisms in seven genes of drug-metabolizing enzymes and transporters were genotyped and the steady state trough concentrations were also determined.

Results

There were significant variances in the steady-state erlotinib trough plasma concentrations, ranging from 315.6 ng/ml to 4479.83 ng/ml. Erlotinib steady state trough concentration was remarkably lower in current smoking patients. The steady state trough concentration of GG in rs1048943 of CYP1A1 was significantly higher than that of AA allele carriers. The polymorphism of CYP1A2 was significantly associated with the severity of skin rash, and the development of diarrhea was associated with SNPs in ABCB1 and CYP3A5. We also observed that GG allele in CYP1A1 was accompanied with a longer PFS in our study.

Conclusion

A large variability of erlotinib steady state trough concentration was found among Chinese Han population. SNPs in CYP1A1 appeared to influence the steady state trough concentration of erlotinib. Correlation between CYP1A2 polymorphisms and severity of skin rash was observed, together with the correlation between the development of diarrhea and SNPs in ABCB1 and CYP3A5.

Pharmacokinetics and Bioequivalence Evaluation of Erlotinib Hydrochloride Tablets: Randomized, Open-Label, 2-Period Crossover Study in Healthy Chinese Subjects

A randomized, open-label, 2-period crossover study was performed to evaluate the pharmacokinetic properties and bioequivalence of 2 erlotinib hydrochloride tablets (a test formulation and a reference formulation) in healthy Chinese subjects. Subjects were randomized to receive a single oral dose of the erlotinib hydrochloride test or reference formulation (150 mg) under fasting conditions. The washout period was 12 days. Blood samples were collected at scheduled time points, and plasma concentrations were determined using a high-performance liquid chromatography-tandem mass spectrometry method. A noncompartmental method was used to calculate pharmacokinetic parameters and to evaluate the bioequivalence of the 2 formulations. Safety assessments were performed during the whole study period. The results suggest that the pharmacokinetic parameter values of the test formulation were similar to those of the reference formulation. The 90% confidence intervals of the geometric least-squares mean ratios of the test to reference formulation were 94.06% to 105.43% for maximum concentration, 88.21% to 97.57% for area under the concentration-time curve to last measurement, and 87.37% to 97.14% for area under the curve extrapolated to infinity, which are all within the accepted bioequivalence range of 80% to 125%. No serious adverse events occurred during the study. These findings suggest that the 2 erlotinib hydrochloride tablets were bioequivalent in accordance with predetermined regulatory criteria.