Differential metabolism of gefitinib and erlotinib by human cytochrome P450 enzymes

Survival Disparities in Black Patients With EGFR-mutated Non-small-cell Lung Cancer

BACKGROUND

Little is known about the difference between black and non-black patients with epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC), particularly regarding survival. We thus characterized the EGFR expression profile, clinical characteristics, and survival outcome in these patients.

PATIENT AND METHODS

We reviewed the cancer registry and patient charts at a New York-Bronx network (n = 2773) treating a large population of minority patients, for non-squamous NSCLC (n = 1986) diagnosed between 2009 and 2015. Survival was adjusted for smoking, gender, age, weight, and stage.

RESULTS

The EGFR mutation rate was 15% (98/652) in tested patients (black, 14%; non-black, 16%). There was no significant difference between the 2 cohorts with respect to age at diagnosis, gender, presenting stages, and socioeconomic status. On the other hand, weight was noted to be heavier in black patients with EGFR-mutated NSCLC than their non-black counterparts (P = .012). After adjusting for gender, age, smoking status, weight, and stage, the multivariate analysis revealed no racial disparity in survival among patients with wild-type EGFR (P = .774); However, among patients with EGFR-mutated NSCLC, black patients had shorter survival in comparison with non-black patients (P = .001), with 2-year survival rates being 33% versus 61%, respectively. Such shorter survival was also observed among EGFR-inhibitor treated patients with common EGFR mutations (P = .040).

CONCLUSIONS

To our knowledge, this is the first report of inferior survival among black patients with NSCLC with EGFR mutations, relative to non-black patients. The survival disparities suggest the need of more tailored management for this patient population.

Delineation of cell death mechanisms induced by synergistic effects of statins and erlotinib in non-small cell lung cancer cell (NSCLC) lines

Hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) have been shown to overcome tyrosine kinase inhibitor (TKI) resistance in epithelial growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC) cells in vivo and in vitro. However, little is known about the putative induction of non-apoptotic cell death pathways by statins. We investigated the effects of pitavastatin and fluvastatin alone or in combination with erlotinib in three NSCLC cell lines and examined the activation of different cell death pathways. We assessed apoptosis via fluorometric caspase assay and poly (ADP-ribose) polymerase 1 (PARP) cleavage. Furthermore, annexinV/propidium iodide (PI) flow cytometry was performed. Small molecule inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD), necrostatin 1 (Nec1), ferrostatin 1 (Fer1), Ac-Lys-Lys-Norleucinal (Calp1) were used to characterise cell death pathway(s) putatively (co-)activated by pitavastatin/erlotinib co-treatment. Synergism was calculated by additivity and isobolographic analyses. Pitavastatin and fluvastatin induced cell death in EGFR TKI resistant NSCLC cells lines A549, Calu6 and H1993 as shown by caspase 3 activation and PARP cleavage. Co-treatment of cells with pitavastatin and the EGFR TKI erlotinib resulted in synergistically enhanced cytotoxicity compared to pitavastatin monotherapy. Flow cytometry indicated the induction of alternative regulated cell death pathways. However, only co-treatment with mevalonic acid (Mev) or the pan-caspase inhibitor zVAD could restore cell viability. The results show that cytotoxicity mediated by statin/erlotinib co-treatment is synergistic and can overcome erlotinib resistance in K-ras mutated NSCLC and relies only on apoptosis.

Decreased Disposition of Anticancer Drugs Predominantly Eliminated via the Liver in Patients with Renal Failure

Background:

Evidence has revealed that renal impairment can affect the systemic exposure of drugs which are predominantly eliminated via the liver. The modulation of drug-metabolizing enzymes and transporters expressed in the liver and/or small intestine by diverse entities, including uremic toxins, in systemic circulation of patients with severe renal failure is considered as the cause of atypical pharmacokinetics, which sometimes induce undesirable adverse events that are especially critical for drugs with narrow therapeutic window such as anticancer drugs. A dosing strategy for anticancer drugs in these patients needs to be established.

Methods:

The effects of renal impairment on the systemic exposure and safety of anticancer drugs were summarized. The proposed mechanisms for the alterations in the pharmacokinetics of these anticancer drugs were also discussed.

Results:

Changes in pharmacokinetics and clinical response were reported in 9 out of 10 cytotoxic anticancer drugs investigated, although available information was limited and sometimes controversial. Systemic exposure of 3 out of 16 tyrosine kinase inhibitors was higher in patients with severe renal failure than that in patients with normal kidney function. An increase in systemic exposure of anticancer drugs in patients with renal impairment is likely to be observed for substrates of OATP1B1, despite the limited evidence.

Conclusion:

The molecular basis for the effect of uremia on non-renal drug elimination still needed to be clarified with further studies to generate generalizable concepts, which may provide insights into establishing better clinical usage of anticancer drugs, i.e. identifying patients at risk and dose adjustment.

Population pharmacokinetics of afatinib and exposure-safety relationships in Japanese patients with EGFR mutation-positive non-small cell lung cancer

To investigate the exposure–safety relationships of afatinib in Japanese population, we performed population pharmacokinetics (PK) analysis of afatinib in Japanese advanced non-small cell lung cancer patients harboring epidermal growth factor receptor mutation. Plasma samples were collected at 0.5–1, 2–3, 8–12, and 24 h after oral afatinib (40 mg) administration on day 1 and day 8. Plasma afatinib concentrations were determined using high-performance liquid chromatography. Data was analyzed following the population approach and using the software Phoenix^® NLME^TM Version 7.0 software (Certara USA, Inc., Princeton, NJ, USA). From 34 patients, a total of 354 afatinib plasma concentration values were available for the population PK analysis. Significant covariates in the population PK model included aspartate aminotransferase and creatinine clearance on CL/F, and age and body mass index on V/F. Results of simulation based on final PK model indicated that hepatic impairment had a significant effect on afatinib levels in plasma after multiple dosing. Afatinib trough plasma concentrations on day 8 were higher in patients with adverse events of grade 3 or higher. The population PK analysis showed that hepatic impairment affected afatinib PK parameters and contributed to the high inter-patient variability and high plasma concentrations of afatinib following multiple treatments.

The analysis of pharmacokinetic and pharmacogenomic impact on gefitinib efficacy in advanced non-small cell lung cancer patients: results from a prospective cohort study

Background

The current study is aimed to examine the impact of pharmacokinetics and gene polymorphisms of enzymes involving in absorption, distribution, metabolism and excretion (ADME) on the efficacy of gefitinib in non-small cell lung cancer (NSCLC) patients.

Methods

Eligible patients with indication of gefitinib treatment were prospectively enrolled in this study. Two peripheral blood samples at baseline and before cycle 2 day 1 were collected for the detection of single nucleotide polymorphisms (SNPs) of drug ADME enzymes and trough drug concentration (C_trough) at steady state. Thirteen SNPs were genotyped using the Sequenom Massarray system. C_trough was determined by validated high-performance liquid chromatographic method with tandem mass spectrometric (LC-MS/MS).

Results

Fifty-eight NSCLC patients were enrolled in this study. The median of C_trough was 175ng/mL (range from 47.8 to 470 ng/mL). The trough concentration was not associated with either objective response or progression free survival (PFS). C_trough was significantly lower in CYP3A4 rs2242480 CC + CT genotype than in TT genotype (P=0.019) and in ABCG2 rs2231142 AA genotype than in AC + CC genotype (P=0.031). ABCB1 rs2032582 dominant model was significantly correlated with overall response rate (ORR) and patients with GG phenotype respond better than patients with GT + TT phenotypes (84.6% vs. 51.2%, P=0.032). ABCB1 rs10256836 recessive model was significantly correlated with PFS and patients with GG phenotype achieved longer PFS than patients with GC + CC phenotypes (17.40 vs. 10.33 months, P=0.040).

Conclusions

The C_trough of gefitinib was significantly different between CYP3A4 and ABCG2 genotypes, but not with the efficacy of gefitinib treatment. ABCB1 rs2032582 and rs10256836 polymorphisms were correlated treatment outcome. Polymorphisms analysis of ABCB1 could be a predictive biomarker for gefitinib treatment.

FDA- and EMA-Approved Tyrosine Kinase Inhibitors in Advanced EGFR-Mutated Non-Small Cell Lung Cancer: Safety, Tolerability, Plasma Concentration Monitoring, and Management

Non-small-cell lung cancer (NSCLC) is the most common form of primary lung cancer. The discovery of several oncogenic driver mutations in patients with NSCLC has allowed the development of personalized treatments based on these specific molecular alterations, in particular in the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) gene. Gefitinib, erlotinib, afatinib, and osimertinib are TK inhibitors (TKIs) that specifically target EGFR and are currently approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) as first line treatment for sensitive EGFR-mutant patients. However, these four drugs are associated with severe adverse events (AEs) that can significantly impact patient health-related quality of life and patient monitoring. EGFR-TKIs are commonly used together with other types of medication that can substantially interact. Here, we review approaches used for the management of TKI-AEs in patients with advanced NSCLC to promote the benefits of treatments and minimize the risk of TKI treatment discontinuation. We also consider potential TKI–drug interactions and discuss the usefulness of plasma concentration monitoring TKIs based on chromatographic and mass spectrometry approaches to guide clinical decision-making. Adjusting the most appropriate therapeutic strategies and drug doses may improve the performance therapy and prognosis of patients with advanced EGFR-mutated NSCLC.

Pharmacokinetics and safety of erlotinib and its metabolite OSI-420 in infants and children with primary brain tumors

PURPOSE

Erlotinib (Tarceva^®), a potent small molecule inhibitor of the epidermal growth factor receptor tyrosine kinase, has been evaluated to treat infants and children with primary brain tumors. The pharmacokinetics of erlotinib and its primary metabolite OSI-420 were characterized and exposure-safety associations were investigated.

METHODS

This analysis involved patients enrolled in two clinical studies and receiving oral erlotinib once daily as part of treatment. Single-dose and steady-state erlotinib and OSI-420 plasma concentrations were assayed using HPLC-MS/MS methods. Population pharmacokinetic modeling and univariate covariate analysis evaluating demographic, clinical and selected CYP3A5, CYP3A4, ABCB1, and ABCG2 genotypes were performed. Associations between erlotinib and OSI-420 pharmacokinetics, and with toxicities (diarrhea and skin rash) occurring post-dose were explored.

RESULTS

Data from 47 patients (0.7-19 years old) were collected and best fitted by one-compartment linear models. Erlotinib and OSI-420 apparent clearances (CL/F and CL_m/F_m) were higher in patients < 5 years compared to older patients (mean CL/F: 6.8 vs 3.6 L/h/m², and mean CL_m/F_m: 79 vs 38 L/h/m², p < 0.001), and were 1.62-fold and 1.73-fold higher in males compared to females (p < 0.01). Moreover, CL/F was 1.53-fold higher in wild-type patients than in patients heterozygous or homozygous mutant for ABCG2 rs55930652 (p < 0.05). Most of the toxicities reported were grade 1. No associations were found between drug pharmacokinetics and drug-induced toxicities.

CONCLUSIONS

Erlotinib therapy was well tolerated by pediatric patients with primary brain tumors. No dosing adjustments based on age or patient characteristics are recommended for this patient population.

Defining the Contribution of CYP1A1 and CYP1A2 to Drug Metabolism Using Humanized CYP1A1/1A2 and Cyp1a1/Cyp1a2 Knockout Mice

Cytochrome P450s CYP1A1 and CYP1A2 can metabolize a broad range of foreign compounds and drugs. However, these enzymes have significantly overlapping substrate specificities. To establish their relative contribution to drug metabolism in vivo, we used a combination of mice humanized for CYP1A1 and CYP1A2 together with mice nulled at the Cyp1a1 and Cyp1a2 gene loci. CYP1A2 was constitutively expressed in the liver, and both proteins were highly inducible by 2,3,7,8-tetrachlorodibenzodioxin (TCDD) in a number of tissues, including the liver, lung, kidney, and small intestine. Using the differential inhibition of the human enzymes by quinidine, we developed a method to distinguish the relative contribution of CYP1A1 or CYP1A2 in the metabolism of drugs and foreign compounds. Both enzymes made a significant contribution to the hepatic metabolism of the probe compounds 7-methoxy and 7-ehthoxyresorufin in microsomal fractions from animals treated with TCDD. This enzyme kinetic approach allows modeling of the CYP1A1, CYP1A2, and non-CYP1A contribution to the metabolism of any substrate at any substrate, inhibitor, or enzyme concentration and, as a consequence, can be integrated into a physiologically based pharmacokinetics model. The validity of the model can then be tested in humanized mice in vivo. SIGNIFICANCE STATEMENT: Human CYP1A1 and CYP1A2 are important in defining the efficacy and toxicity/carcinogenicity of drugs and foreign compounds. In light of differences in substrate specificity and sensitivity to inhibitors, it is of central importance to understand their relative role in foreign compound metabolism. To address this issue, we have generated mice humanized or nulled at the Cyp1a gene locus and, through the use of these mouse lines and selective inhibitors, developed an enzyme kinetic-based model to enable more accurate prediction of the fate of new chemicals in humans and which can be validated in vivo using mice humanized for cytochrome P450-mediated metabolism.

Comparative review of drug-drug interactions with epidermal growth factor receptor tyrosine kinase inhibitors for the treatment of non-small-cell lung cancer

The development of small-molecule tyrosine kinase inhibitors (TKIs) that target the epidermal growth factor receptor (EGFR) has revolutionized the management of non-small-cell lung cancer (NSCLC). Because these drugs are commonly used in combination with other types of medication, the risk of clinically significant drug–drug interactions (DDIs) is an important consideration, especially for patients using multiple drugs for coexisting medical conditions. Clinicians need to be aware of the potential for clinically important DDIs when considering therapeutic options for individual patients. In this article, we describe the main mechanisms underlying DDIs with the EGFR-TKIs that are currently approved for the treatment of NSCLC, and, specifically, the potential for interactions mediated via effects on gastrointestinal pH, cytochrome P450-dependent metabolism, uridine diphosphate-glucuronosyltransferase, and transporter proteins. We review evidence of such DDIs with the currently approved EGFR-TKIs (gefitinib, erlotinib, afatinib, osimertinib, and icotinib) and discuss several information sources that are available online to aid clinical decision-making. We conclude by summarizing the most clinically relevant DDIs with these EFGR-TKIs and provide recommendations for managing, minimizing, or avoiding DDIs with the different agents.

Gene polymorphism of cytochrome P450 significantly affects lung cancer susceptibility

BACKGROUND

Cytochrome P450 (CYPs) are heme proteins involved in the metabolism of a variety of endogenous and exogenous substances and play an important role in the carcinogenesis mechanisms of environmental and hereditary factors. The objective of this study was to investigate how polymorphisms of CYPs correlate with lung cancer (LC) susceptibility.

METHODS

Six single nucleotide polymorphisms (SNPs) were genotyped in this study. The chi-square test and unconditional logistic regression model were used to evaluate the correlation between SNPs and LC susceptibility. The expressions and survival data of genes in patients with LC were mined using Oncomine and Kaplan-Meier Plotter database.

RESULTS

Four SNPs were found to be significantly associated with the risk of LC development (P < 0.05). The most significant correlation was that the A allele and AA genotype of CYP2D6 rs1065852 were associated with increased risk of LC development (adjusted odds ratio [OR] = 1.35, 95% confidence interval [95%CI] = 1.13-1.60, P = 9.04e-4; OR = 1.83, 95%CI = 1.29-2.59, P = 0.001 respectively). Similar association of this variant was also found in the subgroups of male patients, cases in III-IV stages, positive lymph node, squamous cell carcinomas and adenocarcinomas. Whereas rs1065852 was considered as protective factor in females (adjusted OR = 0.33, 95% CI = 0.16-0.70, P = 0.004). In stratified analyses, the association of CYP24A1 rs2762934, CYP24A1 rs6068816, CYP20A1 rs2043449 polymorphism with LC risk appeared stronger in some subgroups. CYP2D6, CYP24A1 and CYP20A1 are overexpressed in some pathological types of LC (P < 0.05), and high levels of CYP2D6 and CYP20A1 indicate poor and good prognosis of LC, respectively.

CONCLUSION

This study revealed that rs1065852, rs2043449, rs2762s934, and rs6068816 of CYPs were associated with LC susceptibility in the Northwestern Chinese Han population; CYP2D6 and CYP20A1 were overexpressed and correlated with prognosis of LC.

Screening for CYP3A4 inhibition and induction coupled to parallel artificial membrane permeability assay (PAMPA) for prediction of botanical-drug interactions: The case of açaí and maca

BACKGROUND

The consumption of botanical dietary supplements (BDS) is a common practice among the US population. However, the potential for botanical-drug interactions exists, and their mechanisms have not been thoroughly studied. CYP3A4 is an important enzyme that contributes to the metabolism of about 60% of clinically used drugs.

PURPOSE

To investigate the potential for botanical-drug interactions of Lepidium meyenii Walpers (maca) root and Euterpe oleracea Mart. (açaí) berries, two commonly used BDS, when co-administered with CYP3A4-metabolized drugs.

METHODS

In an attempt to decrease the general discrepancy between in vivo and in vitro studies, the absorption profiles, particularly for passive diffusion, of plant extracts were investigated. Specifically, the parallel artificial membrane permeability assay (PAMPA) model was utilized to simulate intestinal filtration of passively diffused constituents of açaí and maca extracts. These were subsequently screened for in vitro liver CYP3A4 inhibition and induction. In the inhibition assay, midazolam was used as the probe substrate on genotyped human liver microsomes (CYP3A5 null), and the production of its 1'-substituted metabolite when co-cultured with extract treatments was monitored. In the induction assay, extract treatments were applied to human primary hepatocytes, and quantitative PCR analysis was performed to determine CYP3A4 mRNA expression.

RESULTS

Passively diffused constituents of the methanol açaí extract (IC₅₀ of 28.03 µg/µl) demonstrated the highest inhibition potential, and, at 1.5 µg/µl, induced significant changes in CYP3A4 gene expression. The composition of this extract was further investigated using the chemometric tool Mass Profiler Professional (MPP) on liquid chromatography-mass spectroscopy (LC-MS) data. Subsequently, five compounds of interest characterized by high abundance or high permeability were extracted for further study. This included efforts in effective passive permeability determination and structural elucidation by tandem mass spectrometry (MS/MS).

CONCLUSION

The passively absorbable portion of a methanol açaí extract exhibited inhibition and induction effects on CYP3A4 suggesting the potential to produce botanical-drug interactions.

Erlotinib treatment induces cytochrome P450 3A activity in non-small cell lung cancer patients

AIMS

Erlotinib is a tyrosine kinase inhibitor used in the treatment of non-small cell lung cancer highly metabolized by the cytochrome P450 (CYP) 3A. Hence, CYP3A4 activity might be a useful predictor of erlotinib pharmacokinetics in personalized medicine. The effect of erlotinib on CYP3A activity was therefore studied in non-small cell lung cancer patients.

METHODS

The study included 32 patients scheduled for erlotinib monotherapy. CYP3A activity was assessed using quinine as a probe before and during erlotinib treatment. Plasma from blood samples drawn 16 hours post quinine administration were analysed using HPLC with fluorescence detection to determine the quinine/3-OH-quinine ratio.

RESULTS

Matched samples, available from 13 patients, showed an induction of CYP3A activity (P = 0.003, Wilcoxon's signed rank test) after 2 months of treatment. The quinine/3-OH-quinine ratio decreased from 20.2 (± 13.4) at baseline to 11.0 (± 4.34). Single-point samples, available from 19 patients, supported the decrease in ratio (P = 0.007, Mann-Whitney U-test). Generally, females had a higher CYP3A activity both at baseline and after two months of treatment. Statistical analysis by gender also showed significant increase in CYP3A activity (males, n = 10, P = 0.001, and females, n = 22, P = 0.001).

CONCLUSIONS

An induction of CYP3A activity was observed after 2 months of erlotinib treatment which was also seen when subdividing based on gender. It could be important to take this into consideration for patients co-administering other CYP3A-metabolizing drugs during erlotinib treatment and also makes it difficult to use baseline CYP3A activity to predict erlotinib pharmacokinetics.

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.

Impact of single nucleotide polymorphisms on the efficacy and toxicity of EGFR tyrosine kinase inhibitors in advanced non-small cell lung cancer patients

EGFR tyrosine kinase inhibitors (EGFR-TKIs) are the treatment of choice for advanced-stage (IIIB-IV) NSCLC patients with mutations in EGFR. However, EGFR-TKIs clinical outcomes vary from person to person and these inter-individual differences may be due to genetic factors such as single nucleotide polymorphisms (SNPs). SNPs in genes involved in EGFR-TKIs pharmacodynamics, metabolism and mechanism of action have been demonstrated to be associated with response, survival and toxicity in advanced NSCLC patients treated with EGFR-TKIs. Here we review the influence of gene polymorphisms in the EGFR pathway on clinical outcome and toxicity to EGFR-TKIs in advanced NSCLC patients. The EGFR-216 polymorphism has reported a strong association between response and/or survival to EGFR-TKIs in Caucasian population. Similarly, the effect of EGFR-CA repeats polymorphisms on survival of advanced NSCLC patients treated with EGFR-TKIs have been confirmed both in Caucasian and Asian population. The influence on toxicity of the -216, -191, CA repeats, Arg497Lys and Asp994Asp polymorphisms in EGFR have also been confirmed. Polymorphisms in AKT (rs1130214 and rs1130233) and SMAD3 (rs6494633, rs11071938 and rs11632964) have been associated with survival in advanced NSCLC patients treated with EGFR-TKIs. However, data come from a limited number of studies and need to be confirmed. Finally, polymorphisms in genes coding proteins of the membrane transporters and cytochrome P450 enzymes have been less extensively investigated. There are few studies with small samples, which complicated the generalization of their role in EGFR-TKIs treatment.

Dasatinib significantly reduced in vivo exposure to cyclosporine in a rat model: The possible involvement of CYP3A induction

BACKGROUND

This study was designed to investigate the effects of dasatinib and nilotinib on the pharmacokinetics of cyclosporine in rats, as these drugs have been reported to be cytochrome P450 3A4 (CYP3A4) substrates.

METHODS

Control and test groups (n = 5) were treated with vehicle and dasatinib (4 mg/kg, and 16 mg/kg, oral) or nilotinib (94 mg/kg, oral), respectively, for 8 consecutive days. On day 8, all groups were administered cyclosporine (30 mg/kg) 1 h after the last dose of dasatinib or nilotinib. Blood was collected from the retro-orbital plexus in heparinized tubes at different time points (0, 0.5, 1, 1.5, 2, 3.5, 8, 12, and 24 h). The cyclosporine concentration in blood samples was determined by ultra-performance liquid chromatography-tandem mass spectrometry. The effects of dasatinib on CYP3A2 mRNA and protein expression levels were also investigated.

RESULTS

Dasatinib significantly reduced the maximum blood concentration (Cmax) of cyclosporine by 85.7%, and increased hepatic and intestinal CYP3A2 mRNA and protein expression levels by 2.4- and 1.25-fold, respectively, compared to those in the controls (p <  0.05). On the other hand, nilotinib had no significant effects on cyclosporine pharmacokinetic parameters.

CONCLUSIONS

Dasatinib significantly reduced cyclosporine exposure, which was most probably related to the induction of CYP3A-mediated cyclosporine metabolism.

Oral oncolytic and antiretroviral therapy administration: dose adjustments, drug interactions, and other considerations for clinical use

The rise in non-AIDS defining cancers (NADCs) is emerging as a leading cause of death for HIV and cancer patients. To address this, current literature and guidelines suggest the continuation of antiretroviral therapy (ART) with oral oncolytic agents to prevent adverse complications associated with HIV disease progression. However, such an approach has the potential for drug-drug interactions and adverse events for patients on such therapy. Further, recommendations on how to adjust these medications, when used concomitantly, are limited. As such, our purpose is to evaluate existing literature through such means as drug databases (e.g. Micromedex, Lexi-Comp, etc.) and package inserts along with PubMed/Medline, Embase, and Google Scholar databases to develop a reference tool for providers to utilize when there is a decision to treat a patient with ART and oral oncolytic agents concurrently. Our findings suggest that there are many drug interactions that should be taken into consideration with dual therapy. Metabolism is a key determinant of dose adjustment, and many oncolytic agents and ART agents must have their dose adjusted as such. Most notably, several tyrosine kinase inhibitors require dose increases when used with non-nucleoside reverse transcriptase inhibitors (NNRTIs) but must be decreased when used concomitantly with protease inhibitors (PIs) and cobicistat. Further findings suggest that certain agents should not be used together, which include, but are not limited to, such combinations as bosutinib with NNRTIs, cobicistat, or PIs; idelalisib with maraviroc or PIs; neratinib with NNRTIs, cobicistat, or PIs; and venetoclax with NNRTIs. Overall, the most prominent oncolytic drug interactions were discovered when such agents were used concomitantly with PIs, cobicistat-boosted elvitegravir, or NNRTIs. Future studies are necessary to further evaluate the use of these agents together in disease therapy to generate absolute evidence of such findings. However, from the studies evaluated, much evidence exists to suggest that concomitant therapy is not without drug interactions. As such, clinical decisions regarding concomitant therapy should be evaluated in which the risk and benefit of dual therapy are assessed. Dose adjustments must be made accordingly and in consultation with both HIV and oncology clinicians and pharmacists to reduce the risk for adverse outcomes and disease progression for those with cancer and HIV/AIDS.

Role of Epidermal Growth Factor Receptor (EGFR) and Its Ligands in Kidney Inflammation and Damage

Chronic kidney disease (CKD) is characterized by persistent inflammation and progressive fibrosis, ultimately leading to end-stage renal disease. Although many studies have investigated the factors involved in the progressive deterioration of renal function, current therapeutic strategies only delay disease progression, leaving an unmet need for effective therapeutic interventions that target the cause behind the inflammatory process and could slow down or reverse the development and progression of CKD. Epidermal growth factor receptor (EGFR) (ERBB1), a membrane tyrosine kinase receptor expressed in the kidney, is activated after renal damage, and preclinical studies have evidenced its potential as a therapeutic target in CKD therapy. To date, seven official EGFR ligands have been described, including epidermal growth factor (EGF) (canonical ligand), transforming growth factor-α, heparin-binding epidermal growth factor, amphiregulin, betacellulin, epiregulin, and epigen. Recently, the connective tissue growth factor (CTGF/CCN2) has been described as a novel EGFR ligand. The direct activation of EGFR by its ligands can exert different cellular responses, depending on the specific ligand, tissue, and pathological condition. Among all EGFR ligands, CTGF/CCN2 is of special relevance in CKD. This growth factor, by binding to EGFR and downstream signaling pathway activation, regulates renal inflammation, cell growth, and fibrosis. EGFR can also be “transactivated” by extracellular stimuli, including several key factors involved in renal disease, such as angiotensin II, transforming growth factor beta (TGFB), and other cytokines, including members of the tumor necrosis factor superfamily, showing another important mechanism involved in renal pathology. The aim of this review is to summarize the contribution of EGFR pathway activation in experimental kidney damage, with special attention to the regulation of the inflammatory response and the role of some EGFR ligands in this process. Better insights in EGFR signaling in renal disease could improve our current knowledge of renal pathology contributing to therapeutic strategies for CKD development and progression.

Risk factors for erlotinib-induced hepatotoxicity: a retrospective follow-up study

Background

Erlotinib is a drug used for the treatment of non-small cell lung cancer (NSCLC) and pancreatic cancer. Severe hepatotoxicity was observed in 4% to 31% of patients receiving erlotinib treatment prompting delay or termination of treatment. Only a few factors related to hepatotoxicity of erlotinib have been reported. No study has investigated the role of concomitant medications and erlotinib-induced hepatotoxicity. The aim of this study was to investigate the association between erlotinib-induced hepatotoxicity and various factors including concomitant medications in patients with NSCLC and pancreatic cancer.

Methods

From January 2014 to June 2017, a retrospective study was conducted in patients with NSCLC and pancreatic cancer, who were treated with erlotinib. Various data were reviewed, including sex, age, body weight, height, body surface area (BSA), underlying disease, Eastern Cooperative Oncology Group (ECOG) Performance Status (PS), smoking history, erlotinib dose, EGFR mutation, and concomitant drugs.

Results

The incidence of grade 2 or higher hepatotoxicity in the study group of patients was 17.2%. Multivariate analysis showed a 2.7-fold increase in hepatotoxicity with the concomitant use of CYP3A4 inducers. In NSCLC patients, co-administration of H2-antagonist/PPI increased hepatotoxicity 3.5-fold. Among the demographic factors, liver metastasis and age ≥ 65 years were significant risk factors in all study patients and NSCLC patients, respectively; the attributable risks for liver metastasis and age were 46.3% and 71.8%, respectively. Subgroup analysis using pancreatic cancer patients yielded marginally significant results with CYP3A4 inducers and erlotinib-induced hepatotoxicity. Liver metastasis and CYP3A4 inducers also shortened time to hepatotoxicity 2.1 and 2.3-fold, respectively.

Conclusions

Our study showed that concomitant use of CYP3A4 inducers and H2-antagonist/PPI, liver metastasis, and age ≥ 65 were associated with erlotinib-induced hepatotoxicity. Thus, close monitoring of liver function is recommended, especially in patients using CYP3A4 inducers and anti-acid secreting agents.

Structures of human cytochrome P450 1A1 with bergamottin and erlotinib reveal active-site modifications for binding of diverse ligands

Human cytochrome P450 1A1 (CYP1A1) is an extrahepatic enzyme involved in the monooxygenation of structurally diverse compounds ranging from natural products to drugs and protoxins. Because CYP1A1 has a role in human carcinogenesis, inhibiting its activity may potentially aid in cancer chemoprevention, whereas utilizing CYP1A1's oxidative activity could help selectively activate anticancer prodrugs. Such potential therapeutic purposes require detailed knowledge of CYP1A1's interactions with potential ligands. Known CYP1A1 ligands also vary substantially in size, and it has not been apparent from a single existing CYP1A1 structure how larger, structurally diverse ligands are accommodated within the enclosed active site. Here, two new X-ray structures with the natural product furanocoumarin bergamottin (at 2.85 Å resolution) and the lung cancer drug erlotinib (3.0 Å) revealed binding orientations consistent with the formation of innocuous metabolites and of toxic metabolites, respectively. They also disclosed local changes in the roof of the active site that enlarge the active site and ultimately form a channel to the protein exterior. Although further structural modifications would be required to accommodate the largest CYP1A1 ligands, knowing which components of the active site are malleable provides powerful information for those attempting to use computational approaches to predict compound binding and substrate metabolism by this clinically relevant monooxygenase.

Impaired Liver Function Implied Shorter Progression Free Survival for EGFR Tyrosine Kinase Inhibitors

Background:

Epithelial growth factor receptor tyrosine kinase inhibitor (EGFR TKI) revolutionize the standard of care for advanced non-small cell lung cancer (NSCLC) harboring sensitive EGFR mutation. Liver toxicity is the dose-limiting factor for TKI but its importance is largely overlooked. Here the relationship between the elevation of transaminase and progression-free survival (PFS) was explored.

Methods:

This was a retrospective study where patients with advanced NSCLC were screened. And those treatment-naïve and with sensitive EGFR mutation who were prescribed with EGFR TKI were enrolled. The highest level of transaminase (alanine aminotransferase, ALT, and aspartate transaminase, AST) during the treatment course was recorded.

Results:

Totally 208 patients were recruited, and most of them (48.6%) took gefitinib. The whole cohort achieved a median PFS of 11.2 months (95% CI: 10.0-12.3 m). 73 (35.1%) patients had elevated transaminase and most was attributed to gefitinib (n=43, 42.5%). Specifically, ALT was elevated in 65 patients (31.3%) while AST in 24 patients (11.5%). Again, gefitinib was associated with more cases of ALT (40.6%) and AST (17.8%) elevation. The elevation of AST was not related to PFS (P=0.259, HR=0.751, 95% CI: 0.464-1.214). Interestingly, those with normal ALT level had a longer PFS (12.6m, 95% CI: 10.6-14.5 m) than those with elevated ALT (9.5m 95% CI: 7.9-11.0 m, P=0.025, HR=0.682, 95% CI: 0.488-0.953). The inverse relationship was confirmed in the COX regression analysis (P=0.047).

Conclusion:

This study revealed the side effects of elevated ALT was inversely related to the PFS of EGFR TKI treatment. The liver impairment by TKI should not be overlooked.

Impact of rifampicin-inhibitable transport on the liver distribution and tissue kinetics of erlotinib assessed with PET imaging in rats

Background

Erlotinib is an epidermal growth factor receptor (EGFR)-targeting tyrosine kinase inhibitor approved for treatment of non-small cell lung cancer. The wide inter-individual pharmacokinetic (PK) variability of erlotinib may impact treatment outcome and/or toxicity. Recent in vivo studies reported a nonlinear uptake transport of erlotinib into the liver, suggesting carrier-mediated system(s) to mediate its hepatobiliary clearance. Erlotinib has been identified in vitro as a substrate of organic anion-transporting polypeptide (OATP) transporters which expression does not restrict to hepatocytes and may impact the tissue uptake of erlotinib in vivo.

Results

The impact of rifampicin (40 mg/kg), a potent OATP inhibitor, on the liver uptake and exposure to tissues of ¹¹C-erlotinib was investigated in rats (4 animals per group) using positron emission tomography (PET) imaging. Tissue pharmacokinetics (PK) and corresponding exposure (area under the curve, AUC) were assessed in the liver, kidney cortex, abdominal aorta (blood pool) and the lungs. The plasma PK of parent ¹¹C-erlotinib was also measured using arterial blood sampling to estimate the transfer rate constant (k_uptake) of ¹¹C-erlotinib from plasma into different tissues.

PET images unveiled the predominant distribution of ¹¹C-erlotinib-associated radioactivity to the liver, which gradually moved to the intestine, thus highlighting hepatobiliary clearance. ¹¹C-erlotinib also accumulated in the kidney cortex. Rifampicin did not impact AUC_aorta but reduced k_{uptake, liver} (p < 0.001), causing a significant 27.3% decrease in liver exposure (p < 0.001). Moreover, a significant decrease in k_{uptake, kidney} with a concomitant decrease in AUC_kidney (− 30.4%, p < 0.001) were observed. Rifampicin neither affected k_{uptake, lung} nor AUC_lung.

Conclusions

Our results suggest that ¹¹C-erlotinib is an in vivo substrate of rOATP transporters expressed in the liver and possibly of rifampicin-inhibitable transporter(s) in the kidneys. Decreased ¹¹C-erlotinib uptake by elimination organs did not translate into changes in systemic exposure and exposure to the lungs, which are a target tissue for erlotinib therapy.

Population Pharmacokinetics and Adverse Events of Erlotinib in Japanese Patients with Non-small-cell Lung Cancer: Impact of Genetic Polymorphisms in Metabolizing Enzymes and Transporters

Determinants of interindividual variability in erlotinib pharmacokinetics (PK) and adverse events remain to be elucidated. This study with 50 Japanese non-small-cell lung cancer patients treated with oral erlotinib at a standard dose of 150 mg aimed to investigate whether genetic polymorphisms affect erlotinib PK and adverse events. Single nucleotide polymorphisms (SNPs) in genes encoding metabolizing enzymes (CYP1A1, CYP1A2, CYP2D6, CYP3A4, CYP3A5, UGT1A1, UGT2B7, GSTM1, and GSTT1) or efflux transporters (ABCB1, and ABCG2) were analyzed as covariates in a population PK model. The ABCB1 1236C>T (rs1128503) polymorphism, not ABCB1*2 haplotype (1236TT-2677TT-3455TT, rs1128503 TT-rs2032582 TT-rs1045642 TT), was a significant covariate for the apparent clearance (CL/F), with the TT genotype showing a 29.4% decrease in CL/F as compared with the CC and the CT genotypes. A marginally higher incidence of adverse events (mainly skin rash) was observed in the TT genotype group; however, patients with high plasma erlotinib exposure did not always experience skin rash. None of the other SNPs affected PK or adverse events. The ABCB1 genotype is a potential predictor for erlotinib adverse events. Erlotinib might be used with careful monitoring of adverse events in patients with ABCB1 polymorphic variants.

Nanostructured surfaces for analysis of anticancer drug and cell diagnosis based on electrochemical and SERS tools

Discovering new anticancer drugs and screening their efficacy requires a huge amount of resources and time-consuming processes. The development of fast, sensitive, and nondestructive methods for the in vitro and in vivo detection of anticancer drugs' effects and action mechanisms have been done to reduce the time and resources required to discover new anticancer drugs. For the in vitro and in vivo detection of the efficiency, distribution, and action mechanism of anticancer drugs, the applications of electrochemical techniques such as electrochemical cell chips and optical techniques such as surface-enhanced Raman spectroscopy (SERS) have been developed based on the nanostructured surface. Research focused on electrochemical cell chips and the SERS technique have been reviewed here; electrochemical cell chips based on nanostructured surfaces have been developed for the in vitro detection of cell viability and the evaluation of the effects of anticancer drugs, which showed the high capability to evaluate the cytotoxic effects of several chemicals at low concentrations. SERS technique based on the nanostructured surface have been used as label-free, simple, and nondestructive techniques for the in vitro and in vivo monitoring of the distribution, mechanism, and metabolism of different anticancer drugs at the cellular level. The use of electrochemical cell chips and the SERS technique based on the nanostructured surface should be good tools to detect the effects and action mechanisms of anticancer drugs.

Metabolic Pathway of Icotinib In Vitro: The Differential Roles of CYP3A4, CYP3A5, and CYP1A2 on Potential Pharmacokinetic Drug-Drug Interaction

Icotinib is the first self-developed small molecule drug in China for targeted therapy of non-small cell lung cancer. To date, systematic studies on the pharmacokinetic drug-drug interaction of icotinib were limited. By identifying metabolite generated in human liver microsomes and revealing the contributions of major cytochromes P450 (CYPs) in the formation of major metabolites, the aim of the present work was to understand the mechanisms underlying pharmacokinetic and pharmacological variability in clinic. A liquid chromatography/UV/high-resolution mass spectrometer method was developed to characterize the icotinib metabolites. The formation of 6 major metabolites was studied in recombinant CYP isozymes and human liver microsomes with specific inhibitors to identify the CYPs responsible for icotinib metabolism. The metabolic pathways observed in vitro are consistent with those observed in human. Results demonstrated that the metabolites are predominantly catalyzed by CYP3A4 (77%∼87%), with a moderate contribution from CYP3A5 (5%∼15%) and CYP1A2 (3.7%∼7.5%). The contribution of CYP2C8, 2C9, 2C19, and 2D6 is insignificant. Based on our observations, to minimize drug-drug interaction risk in clinic, coprescription of icotinib with strong CYP3A inhibitors or inducers must be weighed. CYP1A2, a highly inducible enzyme in the smoking population, may also represent a determinant of pharmacokinetic and pharmacological variability of icotinib, especially in lung cancer patients with smoking history.

Lung Toxicity in Non-Small-Cell Lung Cancer Patients Exposed to ALK Inhibitors: Report of a Peculiar Case and Systematic Review of the Literature

Lung toxicity is a potential fatal effect involving non-small-cell lung cancer (NSCLC) patients exposed to tyrosine kinase inhibitors (TKIs). Moving from our experience regarding a patient who developed lung toxicity while receiving 2 different anaplastic lymphoma kinase (ALK)-TKIs, we performed a systematic review to assess the epidemiologic magnitude and the clinical significance of such toxicity in NSCLC patients treated with ALK-TKIs. Studies were identified using MEDLINE and additional sources (European Society for Medical Oncology, American Society of Clinical Oncology, and World Conference on Lung Cancer abstracts) in agreement with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Cochrane guidelines. Lung toxicity was reported in 105 of 4943 NSCLC patients (2.1%). Crizotinib was responsible for pulmonary adverse events (AEs) in 1.8% of exposed patients (49 of 2706). With the limit of a lower number of treated patients (n = 359), brigatinib resulted as the most frequently involved in lung toxicity (7%; n = 25). Pulmonary AEs during therapy with ceritinib, alectinib, and lorlatinib occurred in 1.1%, 2.6%, and 1.8% of the patients, respectively. Sixty-five percent of cases accounted for Grade 3 or 4 events, with a mortality rate of 9%. Radiological patterns of pneumonia were reported in 25 patients, whereas imaging evocative of interstitial lung disease in 37. Overall, 26 of 105 patients (25%) permanently discontinued treatment because of lung toxicity. Lung toxicity is a rare albeit potentially severe side effect in NSCLC patients receiving ALK-TKIs, apparently more frequent with brigatinib. Its early recognition and treatment are crucial for the best outcome of this subgroup of patients, whose overall prognosis is being improved by the availability of several targeted agents.

Use of a physiologically based pharmacokinetic model to simulate drug-drug interactions between antineoplastic and antiretroviral drugs

Background

Co-administration of antineoplastics with ART is challenging due to potential drug-drug interactions (DDIs). However, trials specifically assessing such DDIs are lacking. Our objective was to simulate DDIs between the antineoplastics erlotinib and gefitinib with key antiretroviral drugs and to predict dose adjustments using a physiologically based pharmacokinetic (PBPK) model.

Methods

In vitro data describing chemical properties and pharmacokinetic processes of each drug and their effect on cytochrome P450 isoforms were obtained from the literature. Plasma drug-concentration profiles were simulated in a virtual population of 50 individuals receiving erlotinib or gefitinib alone or with darunavir/ritonavir, efavirenz or etravirine. Simulated pharmacokinetic parameters and the magnitude of DDIs with probe drugs (midazolam, maraviroc) were compared with literature values. Erlotinib and gefitinib pharmacokinetics with and without antiretrovirals were compared and dose-adjustment strategies were evaluated.

Results

Simulated parameters of each drug and the magnitude of DDIs with probe drugs were in agreement with reference values. Darunavir/ritonavir increased erlotinib and gefitinib exposure, while efavirenz and etravirine decreased erlotinib and gefitinib concentrations. Based on our predictions, dose-adjustment strategies may consist of once-daily dosing erlotinib at 25 mg and gefitinib at 125 mg with darunavir/ritonavir; or erlotinib at 200 mg and gefitinib at 375 mg with etravirine. The interaction with efavirenz was not overcome even after doubling erlotinib or gefitinib doses.

Conclusions

PBPK models predicted the in vivo pharmacokinetics of erlotinib, gefitinib and the antiretrovirals darunavir/ritonavir, efavirenz and etravirine, and the DDIs between them. The simulated dose-adjustments may represent valuable strategies to optimize antineoplastic therapy in HIV-infected patients.

Effects of Concomitant Medication Use on Gefitinib-Induced Hepatotoxicity

Gefitinib is a drug used for the treatment of non-small cell lung cancer (NSCLC) patients. Severe hepatotoxicity was observed, but only a few cases have been reported on the hepatotoxicity of gefitinib. This study aimed to investigate the association between gefitinib-induced hepatotoxicity and various factors including concomitant medications in lung cancer patients. From January 2013 to December 2014, a retrospective study was performed with NSCLC patients who were treated with gefitinib. Associations between hepatotoxicity and various factors including concomitant drugs were analyzed. Based on multivariate models, it was found that H2 antagonists, proton pump inhibitors (PPIs), and H2 antagonists or PPIs increased hepatotoxicity by about 1.5- to 1.7-fold. Patients younger than 65 years showed 1.6 times higher hepatotoxicity than those older than 65 years. Patients with EGFR mutations had around 2-fold higher hepatotoxicity, and the percentage of incidence of hepatotoxicity because of exon 19 deletion was 32.7%. Our study showed that anti-acid-secreting agents in addition to age younger than 65 years and EGFR mutation were associated with gefitinib-induced hepatotoxicity. Thus, close monitoring of liver function is recommended, especially for patients using anti-acid-secreting agents.

Cytochrome P450 3A selectively affects the pharmacokinetic interaction between erlotinib and docetaxel in rats

Erlotinib as a first-line drug is used in non-small cell lung cancer (NSCLC) patients with sensitive EGFR mutations, while resistance to this drug will occur after several years of treatment. Therefore, the microtubule disturber docetaxel is introduced as combined regimen in clinical trials. This report investigated the potentials and mechanisms of drug-drug interaction (DDI) between erlotinib and docetaxel using wild type (WT) and Cyp3a1/2 knockout (KO) rats. The erlotinib O-demethylation and docetaxel hydroxylation reactions in the absence or the presence of another drug were analyzed in vitro via the assay of rat liver microsomes. In whole animal studies, erlotinib and docetaxel were given to WT and KO rats individually or jointly, and the pharmacokinetic profiles of these two drugs were analyzed and compared among different groups. The results showed that docetaxel not only inhibited the CYP3A-mediated biotransformation of erlotinib in vitro, but also significantly increased the maximum concentration and systemic exposure of erlotinib in vivo in WT rats. In contrast, the DDI was significantly attenuated in KO rats. On the other hand, erlotinib did not influence docetaxel either in vitro biotransformation or in vivo pharmacokinetic behaviors. These results exhibited the potentials of erlotinib-docetaxel interaction and indicated that the CYP3A played the perpetrating role of docetaxel on erlotinib in rats. A better understanding of this DDI with CYP3A may help the regulation of the use of these two drugs, avoid potential problems, and adjust dose carefully and early in clinic.

Epigallocatechin-3-gallate augments the therapeutic effects of benzo[a]pyrene-mediated lung carcinogenesis

Our previous study found curcumin and vitamin E to have protective effects against benzo[a]pyrene (BaP) exposure in human normal lung epithelial BEAS-2B cells. The first objective of this study was to determine whether epigallocatechin-3-gallate (EGCG) elicited the same response. Co-treatment with 5 µM BaP and 20 µM EGCG in BEAS-2B promoted a significant reduction in cell viability and greater G2/M cell cycle arrest, induction of ROS, and reductions in BaP-induced CYP1A1/CYP1B1/COMT, EGFR, p-Akt (Ser473), p-p53 (Thr55), and survivin mRNA/protein expression, as well as an increase in p-p53 (Ser15). Based on these findings, the second objective was to extend the investigation by developing a novel BaP-transformed BEAS-2B cell line, BEAS-2B_BaP , to examine the effects of EGCG when co-administered with gefitinib, an EGFR tyrosine kinase inhibitor. Cell colony formation assay demonstrated in vitro tumorigenic potential of BEAS-2B_BaP , which had an overexpression of EGFR. Viability testing revealed gefitinib co-treatment with EGCG resulted in more cell death compared with gefitinib alone. Co-treated cells had greater reductions in gefitinib-induced CYP1A1/CYB1B1, EGFR, cyclin D1, p-Akt (Ser473), and survivin mRNA/protein expression, as well as an increase in p-p53 (Ser15). Therefore, EGCG was found to promote greater cytotoxicity to BEAS-2B co-treated with BaP and BEAS-2B_BaP upon gefitinib co-treatment through regulating metabolism enzymes and signaling pathways involving EGFR and p53. These findings suggest that EGCG did not act as a protective compound in BEAS-2B after acute BaP exposure, but has the potential to be a useful adjuvant chemotherapeutic compound when coupled with gefitinib for chemosensitization. © 2017 BioFactors, 43(4):529-539, 2017.

Oxidative stress mediates an increased formation of vascular endothelial growth factor in human hepatocarcinoma cells exposed to erlotinib

The tyrosine kinase inhibitor erlotinib targets the receptor of epidermal growth factor (EGFR) involved in development of hepatocellular carcinoma (HCC).

Although inefficient in established HCC, erlotinib has been recently proposed for HCC chemoprevention. Since Cyp3A4 and Cyp1A2 enzymes metabolize erlotinib in the liver, the insights into the mechanisms of erlotinib effects on liver cells with maintained drug metabolizing activity are needed.

We applied erlotinib to both commercially available (SNU398, Huh7) and established in Austria HCC cell lines (HCC-1.2, HCC-3). Cyp3A4 and Cyp1A2, microarray gene expression, cell viability, LDH release, DHFC fluorescence were assessed. VEGF expression was analysed by real-time RT-PCR and ELISA.

Higher cumulative expression of erlotinib metabolizing enzymes was observed in HCC-1.2 and HCC-3 cells. Gene expression microarray analysis showed upregulation of VEGF signalling by erlotinib. VEGF was increased up to 134 ± 14% (n = 5, p = 0.002) in HCC-1.2, HCC-3 and Huh7 cells. Interventions by Cyp1A2 and Mek2siRNA, MEK inhibitor UO126, diphenylene iodonium, as well as a combination of N-acetylcysteine with selenium all inhibited VEGF upregulation caused by erlotinib.

Thus, erlotinib increases VEGF production by mechanisms involving Cyp1A2, oxidative stress and MEK1/2. VEGF may favour angiogenesis and growth of early HCC tumours limiting the therapeutic and chemopreventive effects of erlotinib.

Gefitinib or erlotinib in previously treated non-small-cell lung cancer patients: a cohort study in Taiwan

Among treatment modalities for lung cancer, the most promising therapy is the use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs). Both erlotinib and gefitinib, the two first‐generation EGFR‐TKIs, exhibit significant clinical responses for patients with lung adenocarcinoma. However, few studies have compared the effects of these two drugs, and results have been inconclusive because of the small sample sizes in these studies. Therefore, this study was conducted to investigate this issue. This retrospective nationwide cohort study enrolled NSCLC patients who received EGFR‐TKIs after previous chemotherapy in Taiwan between 1996 and 2010 from the National Health Insurance Research Database. Clinical response and survival after receiving erlotinib and gefitinib were compared using logistic and Cox regression analyses, respectively. Inverse propensity score weighting and a sensitivity analysis in the EGFR‐TKI responder (clinical improvement by taking EGFR‐TKIs for 90 days), adherent patients (receiving EGFR‐TKI on a daily basis), adenocarcinoma, and adenocarcinoma with second‐line TKIs subgroup were performed for bias adjustment. A total of 7222 patients, including 4592 (63.6%) who received gefitinib, were identified. In the survival analysis, erlotinib was associated with a decline in 1‐year progression‐free survival (PFS) (hazard ratio, HR: 1.15 [1.09–1.21]) and overall survival (OS) (HR: 1.10 [1.03–1.18]). The effects of various TKIs were consistent in the 4939 EGFR‐TKI responders, adherent subgroup, adenocarcinoma subgroup, and adenocarcinoma with second‐line TKIs subgroup. In previously treated EGFT‐TKI‐naive NSCLC patients, those receiving gefitinib exhibited a longer PFS and OS than those receiving erlotinib. Additional large‐scale randomized controlled trials are warranted to confirm this finding.

Pharmacokinetic drug-drug interaction between erlotinib and paracetamol: A potential risk for clinical practice

BACKGROUND

Erlotinib is a tyrosine kinase inhibitor available for the treatment of non-small cell lung cancer. Paracetamol is an analgesic agent, commonly used in cancer patients. Because these drugs are often co-administered, there is an increasing issue of interaction between them.

OBJECTIVE

The aim of the study was to investigate the effect of paracetamol on the pharmacokinetic parameters of erlotinib, as well as the influence of erlotinib on the pharmacokinetics of paracetamol.

METHODS

The rabbits were divided into three groups: the rabbits receiving erlotinib (I_ER), the group receiving paracetamol (II_PR), and the rabbits receiving erlotinib+paracetamol (III_ER+PR). A single dose of erlotinib was administered orally (25mg) and was administered intravenously (35mg/kg). Plasma concentrations of erlotinib, its metabolite (OSI420), paracetamol and its metabolites - glucuronide and sulphate were measured with the validated method.

RESULTS

During paracetamol co-administration we observed increased erlotinib maximum concentration (C_max) and area under the plasma concentration-time curve from time zero to infinity (AUC_0-∞) by 87.7% and 31.1%, respectively. In turn, erlotinib lead to decreased paracetamol AUC_0-∞ by 35.5% and C_max by 18.9%. The mean values of paracetamol glucuronide/paracetamol ratios for C_max were 32.2% higher, whereas paracetamol sulphate/paracetamol ratios for C_max and AUC_0-∞ were 37.1% and 57.1% lower in the II_PR group, when compared to the III_ER+PR group.

CONCLUSIONS

Paracetamol had significant effect on the enhanced plasma exposure of erlotinib. Additionally, erlotinib contributed to the lower concentrations of paracetamol. Decreased glucuronidation and increased sulphation of paracetamol after co-administration of erlotinib were also observed.

Complete remission of liver metastasis in a lung cancer patient with epidermal growth factor mutation achieved with Icotinib

A 65‐year‐old Chinese male was referred to our hospital for epidermal growth factor receptor (EGFR)‐mutated advanced non‐small cell lung cancer (NSCLC). Aggressive combined therapy with surgical resection of the right upper lung lesion and chemotherapy was performed. One month later, continued Icotinib treatment was used as magnetic resonance imaging revealed liver metastasis (LM). Interestingly, complete remission of the patient's LM lesions was achieved in six months. To our knowledge, this is the first report documenting a successful case of an NSCLC patient with LM treated with Icotinib after receiving a radical resection for pulmonary carcinoma. Our experience could provide a treatment strategy for patients with similar disease.

Gefitinib in the treatment of nonsmall cell lung cancer with activating epidermal growth factor receptor mutation

Lung cancer is still the main cause of cancer-related deaths worldwide, with most patients present with advanced disease and poor long-term prognosis. The aim of lung cancer treatment is to slow down the progression of the disease, to relieve the patients from the lung cancer symptoms and whenever possible, to increase the overall survival. The discovery of small molecule targeting tyrosine kinase of epidermal growth factor receptor opens a new way in the management of advanced nonsmall cell lung cancer (NSCLC). This review will discuss several Phase II and III trials evaluated the clinical efficacy of gefitinib as monotherapy in pretreated patients with advanced NSCLC, as well as both monotherapy and combined with chemotherapy in chemotherapy-naive patients.

Effects of polymorphisms in CYP2D6 and ABC transporters and side effects induced by gefitinib on the pharmacokinetics of the gefitinib metabolite, O-desmethyl gefitinib

We investigated the effects of polymorphisms in CYP2D6, ABCB1, and ABCG2 and the side effects induced by gefitinib on the pharmacokinetics of O-desmethyl gefitinib, the active metabolite of gefitinib. On day 14 after beginning therapy with gefitinib, plasma concentrations of gefitinib and O-desmethyl gefitinib were measured. Patients were grouped into three groups according to their combination of CYP2D6 alleles: homozygous extensive metabolisers (EMs; *1/*1, *1/*2, and *2/*2; n = 13), heterozygous EMs (*1/*5, *2/*5, *1/*10, and *2/*10; n = 18), and intermediate metabolisers (IMs; *5/*10 and *10/*10; n = 5). The median AUC0-24 of O-desmethyl gefitinib in CYP2D6 IMs was 1460 ng h/mL, whereas that in homozygous EMs was 12,523 ng h/mL (P = 0.021 in univariate analysis). The median AUC ratio of O-desmethyl gefitinib to gefitinib differed among homozygous EMs, heterozygous EMs, and IMs at a ratio of 1.41:0.86:0.24 (P = 0.030). On the other hand, there were no significant differences in the AUC0-24 of O-desmethyl gefitinib between ABCB1 and ABCG2 genotypes. In a multivariate analysis, CYP2D6 homozygous EMs (P = 0.012) were predictive for a higher AUC0-24 of O-desmethyl gefitinib. The side effects of diarrhoea, skin rash, and hepatotoxicity induced by gefitinib were unrelated to the AUC0-24 of O-desmethyl gefitinib. CYP2D6 polymorphisms were associated with the formation of O-desmethyl gefitinib from gefitinib. In CYP2D6 homozygous EMs, the plasma concentrations of O-desmethyl gefitinib were higher over 24 h after taking gefitinib than those of the parent compound; however, side effects induced by gefitinib were unrelated to O-desmethyl gefitinib exposure.

Determinants of Gefitinib toxicity in advanced non-small cell lung cancer (NSCLC): a pharmacogenomic study of metabolic enzymes and transporters

Skin rash, diarrhea and hepatotoxicity are the most common toxicities of Gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. The present study investigated the effects of genetic polymorphisms of drug target, metabolizing enzymes and transporters on Gefitinib toxicities. Thirty single-nucleotide polymorphisms, including EGFR, cytochromes P450 and ATP-binding cassette (ABC), were genotyped by matrix-assisted laser desorption/ionization time-of-flight platform in 59 non-small cell lung cancer patients treated with Gefitinib. Correlation analyses were performed to evaluate their effects on Gefitinib-induced toxicities. ABCB1 rs1128503 TT genotype was a significant high-risk determinant of both skin rash and diarrhea, with 15.78- and 10.78-fold of incident risk increased, respectively. (odds ratio (OR)=15.78, 95% confidence interval (CI) 2.01-124.1, P=0.0087; OR=10.78, 95% CI 1.54-75.40, P=0.0166 vs non-TT genotypes). Patients with ABCB1 rs1128503 TT genotype had greater risk of skin rash and diarrhea. Therefore, polymorphism analyses of ABCB1 might be beneficial to optimize Gefitinib treatment.

Role of gefitinib in the targeted treatment of non-small-cell lung cancer in Chinese patients

Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer. Conventional treatment options have limited efficacy because most cases are in the advanced stage at the time of diagnosis. In recent years, gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has shown its good antitumor activities in treating NSCLC in a number of studies. This paper reviews its role in the targeted treatment of NSCLC in Chinese patients.