Relationship Among Gefitinib Exposure, Polymorphisms of Its Metabolizing Enzymes and Transporters, and Side Effects in Japanese Patients With Non-Small-Cell Lung Cancer

Genetic Variants in the ABCB1 and ABCG2 Gene Drug Transporters Involved in Gefitinib-Associated Adverse Reaction: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to verify the association between the genetic variants of adenosine triphosphate (ATP)-binding cassette subfamily B member 1 (ABCB1) and ATP-binding cassette subfamily G member 2 (ABCG2) genes and the presence and severity of gefitinib-associated adverse reactions. We systematically searched PubMed, Virtual Health Library/Bireme, Scopus, Embase, and Web of Science databases for relevant studies published up to February 2024. In total, five studies were included in the review. Additionally, eight genetic variants related to ABCB1 (rs1045642, rs1128503, rs2032582, and rs1025836) and ABCG2 (rs2231142, rs2231137, rs2622604, and 15622C>T) genes were analyzed. Meta-analysis showed a significant association between the ABCB1 gene rs1045642 TT genotype and presence of diarrhea (OR = 5.41, 95% CI: 1.38-21.14, I2 = 0%), the ABCB1 gene rs1128503 TT genotype and CT + TT group and the presence of skin rash (OR = 4.37, 95% CI: 1.51-12.61, I2 = 0% and OR = 6.99, 95%CI: 1.61-30.30, I2= 0%, respectively), and the ABCG2 gene rs2231142 CC genotype and presence of diarrhea (OR = 3.87, 95% CI: 1.53-9.84, I2 = 39%). No ABCB1 or ABCG2 genes were positively associated with the severity of adverse reactions associated with gefitinib. In conclusion, this study showed that ABCB1 and ABCG2 variants are likely to exhibit clinical implications in predicting the presence of adverse reactions to gefitinib.

The Chimera of TPGS and Nanoscale Lipid Carriers as Lymphatic Drug Delivery Vehicles to Fight Metastatic Cancers

The lymphatic system (LS) plays a crucial role in fluid balance, transportation of macromolecules, and immune response. Moreover, LS is a channel for microbial invasion and cancer metastasis. Particularly, solid tumors, including lung, breast, melanoma, and prostate cancers, are metastasized across highways of LS. Subsequently, the fabrication of chimeric lymphatic drug delivery systems (LDDS) is a promising strategy to fight cancer metastasis and control microbial pandemics. In this regard, LDDS, in terms of PEG-nanoscaled lipid carriers, elicited a revolution during the COVID-19 pandemic as cargoes for mRNA vaccines. The drug delivered by the lymphatic pathway escapes first-pass metabolism and enhances the drug's bioavailability. Ample approaches, including synthesis of prodrugs, trigging of chylomicron biosynthesis, and fabrication of nanocarriers, facilitate lymphatic drug delivery. Specifically, nanoscales lipid cargoes have the propensity to lymphatic trafficking. Interestingly, TPGSengineered nanoscale lipid cargoes enhance lymphatic trafficking, increase tissue permeation, and, specifically, uptake. Moreover, they overcome biological barriers, control biodistribution, and enhance organelles localization. Most anticancer agents are non-specific, have low bioavailability, and induced drug resistance. Therefore, TPGS-engineered nanoscale lipid chimeras improve the therapeutic impact of anticancer agents. This review highlights lymphatic cancer metastasis, nanoscales lipid cargoes as LDDS, and their influence on lymphatic trafficking, besides the methods of LDD 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.

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).

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

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 CYP3A4/5 and ABC transporter polymorphisms on osimertinib plasma concentrations in Japanese patients with non-small cell lung cancer

The effects of polymorphisms in CYP3A4 (20230G > A), CYP3A5 (6986A > G), ABCB1 (1236C > T, 2677G > T/A, 3435C > T), ABCG2 (421C > A), and ABCC2 (-24C > T) on the area under the concentration-time curve (AUC) of osimertinib in 23 patients with non-small cell lung cancer were investigated. Blood sampling was performed just prior to and at 1, 2, 4, 6, 8, 12, and 24 h after osimertinib administration at the steady-state on day 15 after beginning therapy. The osimertinib AUC_0-24 was significantly correlated with age (P = 0.038), serum albumin (P = 0.002), and serum creatinine (P = 0.012). Additionally, there were significant differences in the AUC_0-24 of osimertinib among the groups administered vonoprazan, histamine 2-receptor antagonists or esomeprazole, and no acid suppressants (P = 0.021). By contrast, there were no significant differences in the AUC_0-24 of osimertinib between genotypes of CYP3A4/5 or ABC transporters. Furthermore, there were no significant differences in the AUC_0-24 of osimertinib between patients with diarrhea, skin rash, or hepatotoxicity and those without these conditions. In multivariate analysis, only serum albumin value was an independent factor predicting the AUC_0-24 of osimertinib. Analysis of CYP3A4/5 and ABC transporter polymorphisms before osimertinib therapy may not predict the efficacy or side effects of osimertinib. The lower serum albumin values were associated with an increase in the AUC_0-24 of osimertinib; however, further studies are needed to assess the factors contributing to the interindividual variability of osimertinib pharmacokinetics.

Association of genetic polymorphisms of CYP3A4 and CYP2D6 with gefitinib-induced toxicities

Dermatological, gastrointestinal and hepatic toxicities are the most common adverse events associated with gefitinib use. Gefitinib is metabolized by cytochrome P450. Inconsistent associations of single nucleotide genetic polymorphisms of CYP450 and gefitinib-induced adverse effects were reported. We aim to investigate the association between CYP450 genetic polymorphism and the development of gefitinib-associated adverse events. A retrospective cohort study of Chinese patients with metastatic nonsmall cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations who received first-line gefitinib treatment was conducted. Single nucleotide polymorphisms (SNPs) of CYP2D6, CYP3A4 and CYP3A5 were assayed using a multiplex SNP microarray. Risks of development of gefitinib-induced toxicities associated with different SNPs were determined. Among the 152 patients treated with gefitinib, 52 (34.2%) had gefitinib-induced hepatotoxicity, 113 (74.3%) had cutaneous reactions and 53 (34.9%) had gastrointestinal adverse effects. CYP2D6*41 CT, CYP2D6*10 AA and CYP3A4*1/*1G TT genotypes were significantly associated with hepatic, cutaneous and gastrointestinal adverse effects [odds ratio (OR) 3.773; (95% confidence interval {CI},1.046-13.610; P = 0.043), 3.368 (95% CI, 1.000-11.345; P = 0.050) and 20.000 (95% CI, 2.381-167.965; P = 0.006), respectively]. CYP2D6*41 CT, CYP2D6*10 AA and CYP3A4*1/*1G TT genotypes may be associated with increased risks of gefitinib-induced toxicities in the liver, skin and gastrointestinal tract.

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.

FOXO3 mutation predicting gefitinib-induced hepatotoxicity in NSCLC patients through regulation of autophagy

Hepatotoxicity is a common side effect for patients treated with gefitinib, but the related pathogenesis is unclear and lacks effective predictor and management strategies. A multi-omics approach integrating pharmacometabolomics, pharmacokinetics and pharmacogenomics was employed in non-small cell lung cancer patients to identify the effective predictor for gefitinib-induced hepatotoxicity and explore optional therapy substitution. Here, we found that patients with rs4946935 AA, located in Forkhead Box O3 (FOXO3) which is a well-known autophagic regulator, had a higher risk of hepatotoxicity than those with the GA or GG variant (OR = 18.020, 95%CI = 2.473 to 459.1784, P = 0.018) in a gefitinib-concentration dependent pattern. Furthermore, functional experiments identified that rs4946935_A impaired the expression of FOXO3 by inhibiting the promotor activity, increasing the threshold of autophagy initiation and inhibiting the autophagic activity which contributed to gefitinib-induced liver injury. In contrast, erlotinib-induced liver injury was independent on the variant and expression levels of FOXO3. This study reveals that FOXO3 mutation, leading to autophagic imbalance, plays important role in gefitinib-induced hepatotoxicity, especially for patients with high concentration of gefitinib. In conclusion, FOXO3 mutation is an effective predictor and erlotinib might be an appropriately and well-tolerated treatment option for patients carrying rs4946935 AA.

Precision Dosing of Targeted Therapies Is Ready for Prime Time

Fixed dosing of oral targeted therapies is inadequate in the era of precision medicine. Personalized dosing, based on pharmacokinetic (PK) exposure, known as therapeutic drug monitoring (TDM), is rational and supported by increasing evidence. The purpose of this perspective is to discuss whether randomized studies are needed to confirm the clinical value of precision dosing in oncology. PK-based dose adjustments are routinely made for many drugs and are recommended by health authorities, for example, for patients with renal impairment or for drug-drug interaction management strategies. Personalized dosing simply extrapolates this paradigm from selected patient populations to each individual patient with suboptimal exposure, irrespective of the underlying cause. If it has been demonstrated that exposure is related to a relevant clinical outcome, such as efficacy or toxicity, and that exposure can be optimized by PK-guided dosing, it could be logically assumed that PK-guided dosing would result in better treatment outcomes without the need for randomized confirmatory trials. We propose a path forward to demonstrate the clinical relevance of individualized dosing of molecularly-targeted anticancer drugs.

An Liquid Chromatography-Tandem Mass Spectrometry Method for the Simultaneous Determination of Afatinib, Alectinib, Ceritinib, Crizotinib, Dacomitinib, Erlotinib, Gefitinib, and Osimertinib in Human Serum

BACKGROUND

Routine therapeutic drug monitoring is a promising approach for the rational use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and anaplastic lymphoma kinase (ALK) inhibitors. The purpose of this study was to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of 5 EGFR-TKIs (afatinib, dacomitinib, erlotinib, gefitinib, and osimertinib) and 3 ALK inhibitors (alectinib, ceritinib, and crizotinib).

METHODS

A 100-mL aliquot of serum was diluted with 100 μL of 1% aqueous ammonia containing internal standards and then purified using the supported liquid extraction method. LC-MS/MS was conducted in positive ionization mode, and the method was validated according to published guidelines.

RESULTS

Calibration curves were linear across concentration ranges examined. The intra- and interassay accuracies were 90.7%-110.7% and 94.7%-107.6%, respectively. All intra- and interassay imprecision values were ≤10.1%. The EGFR-TKIs and ALK inhibitors examined in this study, except osimertinib, which could be stored on ice for at least 5 hours, were stable at room temperature for 3 hours. For the internal standard-normalized matrix factors, the mean recovery and percent coefficient of variation values ranged between 54%-112% and 1.7%-11.7%, respectively. This method successfully determined serum concentrations of afatinib, alectinib, erlotinib, gefitinib, and osimertinib in clinical samples. Serum levels of kinase inhibitors consistently reflected those reported in previous studies.

CONCLUSIONS

An LC-MS/MS method suitable for the simultaneous determination of 5 EGFR-TKIs and 3 ALK inhibitors in serum was developed and validated. The newly developed method enabled the determination of 5 of 8 target drugs examined in clinical samples. However, a large number of clinical samples need to be analyzed to verify the usefulness of the method.

Therapeutic drug monitoring of oral targeted antineoplastic drugs

PURPOSE

This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed.

METHODS

A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted.

RESULTS

OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy.

CONCLUSION

Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.

ABCB1, ABCG2, ABCC1, ABCC2, and ABCC3 drug transporter polymorphisms and their impact on drug bioavailability: what is our current understanding?

INTRODUCTION

Interindividual differences in drug response are a frequent clinical challenge partly due to variation in pharmacokinetics. ATP-binding cassette (ABC) transporters are crucial determinants of drug disposition. They are subject of gene regulation and drug-interaction; however, it is still under debate to which extend genetic variants in these transporters contribute to interindividual variability of a wide range of drugs.

AREAS COVERED

This review discusses the current literature on the impact of genetic variants in ABCB1, ABCG2 as well as ABCC1, ABCC2, and ABCC3 on pharmacokinetics and drug response. The aim was to evaluate if results from recent studies would increase the evidence for potential clinically relevant pharmacogenetic effects.

EXPERT OPINION

Although enormous efforts have been made to investigate effects of ABC transporter genotypes on drug pharmacokinetics and response, the majority of studies showed only weak if any associations. Despite few unique results, studies mostly failed to confirm earlier findings or still remained inconsistent. The impact of genetic variants on drug bioavailability is only minor and other factors regulating the transporter expression and function seem to be more critical. In our opinion, the findings on the so far investigated genetic variants in ABC efflux transporters are not suitable as predictive biomarkers.

Crizotinib and Sunitinib Induce Hepatotoxicity and Mitochondrial Apoptosis in L02 Cells via ROS and Nrf2 Signaling Pathway

Considerable attention has been raised on crizotinib- and sunitinib-induced hepatotoxicity, but the underlying mechanisms need further examination. In addition, limited therapeutic strategies exist to reduce the liver damage caused by crizotinib and sunitinib. This study investigated the mechanisms of crizotinib- and sunitinib-induced hepatotoxicity and the potential mitigation through ROS and Nrf2 signaling. Firstly, crizotinib and sunitinib reduced cell viability in human liver cells (L02 cells) and triggered dramatic liver injury in mice. Subsequently, we found that crizotinib and sunitinib activated the oxidative stress response (decreased level of GPx and SOD, and increased MDA content) in vivo. Crizotinib and sunitinib also stimulated hepatocyte mitochondrial apoptosis and necrosis in L02 cells in a dose-dependent manner. In vivo studies further confirmed that crizotinib and sunitinib decreased mitochondrial membrane potential and activated apoptosis-associated proteins (cleaved-PARP, cleaved caspase3, cytochrome c, Bcl2 and Bax). Furthermore, mechanistic investigations demonstrated that crizotinib and sunitinib accumulated ROS and inhibited Nrf2 signaling, and that ROS scavenger NAC and Nrf2 agonist tBHQ alleviated the extent of cell damage and the mitochondrial apoptosis during crizotinib- and sunitinib-induced hepatotoxicity in L02 cells. Collectively, these findings indicated that NAC and tBHQ play the crucial roles in crizotinib- and sunitinib-induced mitochondrial apoptosis via the regulation of oxidative stress.

Establishment and application of a predictive model for gefitinib-induced severe rash based on pharmacometabolomic profiling and polymorphisms of transporters in non-small cell lung cancer

•

A total of 346 patients were enrolled in this study.

•

Severe rash (grade 3&4) did not gain more bonification compare to grade 1&2 rash.

•

Gefitinib and its four metabolites were detected in patients’ plasma.

•

A specific and sensitive predictive model were established based on pharmacometabolomic profiling and pharmacogenomics approach.

Background

Rash is a well-known predictor of survival for patients with gefitinib therapy with non-small cell lung cancer (NSCLC). However, whether patients with more severe rash obtain the more survival benefits from gefitinib is still unknown, and predicted model for severe rash is needed.

Methods

The relationship between gefitinib-induced rash and progression free survival (PFS) was primarily explored in the retrospective cohort. The association between rash and gefitinib/metabolites concentration and genetic polymorphisms were determined by pharmacometabolomic and pharmacogenomics methods in the exploratory cohort and validated in an external cohort.

Results

The survival for patients with rash was significantly higher than that of patients without rash (p = 0.0002, p = 0.0089), but no difference was found between grade 1/2 or grade 3/4. Only the concentration of gefitinib, but not its metabolites, was found to be associated with severe rash, and the cutoff value of gefitinib was 204.6 ng/mL conducted by ROC curve analysis (AUC=0.685). A predictive model for severe rash was established: gefitinib concentration (OR = 11.523, 95% CI = 2.898-64.016, p = 0.0016), SLC22A8 rs4149179(CT vs CC, OR = 3.156, 95% CI = 0.958–11.164, p = 0.0629), SLC22A1 rs4709400(CG vs CC, OR = 10.267, 95% CI = 2.067–72.465, p = 0.0087; GG vs CC, OR = 5.103, 95% CI = 1.032–33.938, p = 0.061). This model was confirmed in the validation cohort with an excellent predictive ability (AUC = 0.749, 95% CI = 0.710–0.951).

Conclusions

Our finding demonstrated that the incidence, not the severity, of gefitinib-induced rash predicted improved survival, the gefitinib concentration and polymorphisms of SLC22A8 and SLC22A1 were recommended to manage severe rash.

An investigation into possible interactions among four vascular epidermal growth factor receptor-tyrosine kinase inhibitors with gefitinib

The objective of present work is to evaluate possible interactions among four clinically-used vascular epidermal growth factor receptor (VEGFR)-tyrosine kinase inhibitors (TKIs), including apatinib, cabozantinib, sorafenib, and sunitinib, with epidermal growth factor receptor (EGFR)-TKI gefitinib. This may advance knowledge regarding possible dual-target suppression strategies for advanced NSCLC, including VEGFR-TKI plus EGFR-TKI. The in vitro metabolism study demonstrated that apatinib inhibited the formation of metabolite M537194 with moderate effect, and inhibited another metabolite formation of M523595 with strong effect, in both human and rat liver microsomes. Sorafenib, cabozantinib, and sunitinib had no significant inhibitory effect on gefitinib metabolism. The results of the in vivo pharmacokinetics study were consistent with the in vitro metabolism study: the AUC_0-t, AUC_0-∞ and C_max of gefitinib increased significantly when co-administered with apatinib by 26.8, 28.7, and 19.8%, respectively. Cabozantinib, sorafenib, and sunitinib exhibited no effect on gefitinib pharmacokinetics. Molecular docking was applied to investigate the binding mode between TKIs and CYP2D6. The docking results illustrated that binding characteristics of apatinib and gefitinib with CYP2D6 were similar, which accounts for competitive mechanism of apatinib-inhibited gefitinib metabolism. In summary, apatinib inhibited the metabolism of gefitinib in vitro and in vivo that were mediated by CYP2D6 and CYP3A4. In addition, cabozantinib, sorafenib, and sunitinib expressed no interaction with gefitinib. The results of the present study may provide a basis and valuable information for the development of treatment strategies.

Hepatotoxicity with epidermal growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer patients: A network meta-analysis

WHAT IS KNOWN AND OBJECTIVE

The efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in patients diagnosed with non-small-cell lung cancer (NSCLC) has been confirmed by a large number of studies. However, hepatotoxicity caused by EGFR-TKIs has not been widely investigated. This review compares the hepatotoxicity of different EGFR-TKIs through a network meta-analysis.

METHODS

PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were systematically searched from their individual inceptions to 20 May 2020 with the goal of identifying randomized controlled trials (RCTs) reporting hepatotoxicity in NSCLC patients receiving EGFR-TKIs. A random-effects pairwise meta-analysis and network meta-analysis were performed within a frequentist framework. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Twelve eligible RCTs, including data from 6,280 patients diagnosed with NSCLC, were analysed. In our network meta-analysis, gefitinib was associated with a higher risk for hepatotoxicity compared to placebo (RR, 2.55; 95% CI, 1.32-4.89) and dacomitinib (RR, 2.60; 95% CI, 1.30-5.20) in terms of all-grades alanine transaminase (ALT) elevation. As for all-grades aspartate transaminase (AST) elevation, gefitinib and erlotinib showed a significantly increased risk for hepatotoxicity compared to afatinib, dacomitinib and placebo (erlotinib vs. afatinib: RR, 1.85; 95% CI, 1.05-3.24; erlotinib vs. dacomitinib: RR, 1.68; 95% CI, 1.19-2.36; erlotinib vs. placebo: RR, 3.38; 95% CI, 1.69-6.73; gefitinib vs. afatinib: RR, 2.23; 95% CI, 1.32-3.79; gefitinib vs. dacomitinib: RR, 2.03; 95% CI, 1.51-2.73; gefitinib vs. placebo: RR, 4.08; 95% CI, 2.11-7.91). There was a high risk of high-grade ALT elevation in patients treated with gefitinib compared to patients treated with erlotinib (RR, 4.31; 95% CI, 2.15-8.66), dacomitinib (RR, 6.95; 95% CI, 1.85-26.05) or placebo (RR, 8.38; 95% CI, 1.56-45.01). No statistically significant differences were identified among the five agents analysed in terms of all-grades TB elevation and high-grade AST elevation. The surface under the cumulative ranking curve (SUCRA) revealed that gefitinib showed a potentially higher risk for ALT and AST elevation compared to other EGFR-TKIs regardless of grade.

WHAT IS NEW AND CONCLUSION

Current evidence indicates that the association between afatinib or dacomitinib and risk of liver enzyme elevation remains uncertain in patients diagnosed with NSCLC. Some evidence suggests that gefitinib and erlotinib may be associated with a significantly increased risk for hepatotoxicity in patients with NSCLC. However, given that the elevation of liver enzymes was not definitely associated with EGFR-TKIs and publication bias, further studies are required to confirm these results.

Pharmacogenomics to Predict Tumor Therapy Response: A Focus on ATP-Binding Cassette Transporters and Cytochromes P450

Pharmacogenomics is an evolving tool of precision medicine. Recently, due to the introduction of next-generation sequencing and projects generating "Big Data", a plethora of new genetic variants in pharmacogenes have been discovered. Cancer resistance is a major complication often preventing successful anticancer treatments. Pharmacogenomics of both somatic mutations in tumor cells and germline variants may help optimize targeted treatments and improve the response to conventional oncological therapy. In addition, integrative approaches combining copy number variations and long noncoding RNA profiling with germline and somatic variations seem to be a promising approach as well. In pharmacology, expression and enzyme activity are traditionally the more studied aspects of ATP-binding cassette transporters and cytochromes P450. In this review, we briefly introduce the field of pharmacogenomics and the advancements driven by next-generation sequencing and outline the possible roles of genetic variation in the two large pharmacogene superfamilies. Although the evidence needs further substantiation, somatic and copy number variants as well as rare variants and common polymorphisms in these genes could all affect response to cancer therapy. Regulation by long noncoding RNAs has also been shown to play a role. However, in all these areas, more comprehensive studies on larger sets of patients are needed.

Effects of STAT3 polymorphisms and pharmacokinetics on the clinical outcomes of gefitinib treatment in patients with EGFR-mutation positive non-small cell lung cancer

WHAT IS KNOWN AND OBJECTIVE

We investigated the correlations among signal transducer and activator of transcription 3 (STAT3) rs4796793C >G polymorphism, gefitinib pharmacokinetics and clinical responses in Japanese patients with non-small cell lung cancer receiving gefitinib therapy.

METHODS

Forty-five patients were enrolled in this study. Plasma trough concentrations (C₀ ) of gefitinib at the steady-state were measured by high-performance liquid chromatography.

RESULTS AND DISCUSSION

Patients having a gefitinib C₀ of at least ≥200 ng/mL had significantly longer PFS than patients having a C₀ of <200 ng/mL (median [95% confidence interval (CI)] PFS: 11.0 [8.2-13.7] and 5.3 [0.0-12.0] months, respectively, P = .042). There were no significant differences in PFS between patients with STAT3 rs4796793C/C and G alleles; however, patients with STAT3 rs4796793C/C having a gefitinib C₀ of ≥ 200 ng/mL had significantly longer progression-free survival (PFS) and overall survival (OS) than those with a C₀ of <200 ng/mL (median [95% CI] PFS: 11.4 [4.1-18.6] and 3.0 [0.0-7.0] months, respectively, P = .008; median [95% CI] OS: 20.6 [7.4-33.7] and 12.6 [10.1-15.1] months, respectively, P = .042). In patients with the STAT3 rs4796793G allele, there were no significant differences in PFS and OS between the two gefitinib C₀ groups. In addition, there were no significant differences in PFS or OS according to smoking, presence of proton pump inhibitor combination, or onset of side effects.

WHAT IS NEW AND CONCLUSION

Clinical outcomes of gefitinib in patients with the STAT3 rs4796793C/C genotype depended on plasma concentrations of gefitinib. In addition to information regarding EGFR mutations, the STAT3 rs4796793C >G polymorphism and gefitinib C₀ may be potential predictors of clinical outcomes after beginning of gefitinib therapy.

A meta-analysis of ABCG2 gene polymorphism and non-small cell lung cancer outcomes

We aimed to analyze the correlation between ABCG2 gene polymorphisms of 34 GG/(GA + AA) loci, 421 CC/(AC + AA) loci, and non-small cell lung cancer (NSCLC) therapeutic effects via meta-analysis. With key words, the databases PubMed and EMBASE were searched for clinical studies on ABCG2 polymorphism and NSCLC. RR and 95% CIs were used to compute combined effects, followed by heterogeneity testing. Publication bias was examined using the funnel plot method. Review Manager 5.3 software was used for the meta-analysis. Ten studies were included. No evidence of heterogeneity exists in these studies. The results indicate that two polymorphic loci of ABCG2 gene (34 G>A, and 421 C>A) had no relationship with the curative effect of chemotherapy for NSCLC, except ABCG2 34G>A, which had a significant relationship with the skin toxicity complication. There was no significant relationship between these polymorphisms and complications (skin toxicity, diarrhea, interstitial pneumonia, liver dysfunction, and neutropenia). Begg’s test and Egger’s test indicated that there was no obvious publication bias. The meta-analysis indicated that there was no significant correlation between ABCG2 gene polymorphism and NSCLC outcomes.

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.

Correlation between adverse events after drug treatment and the MDR1 C3435T polymorphism in advanced non-small cell lung cancer patients in an Asian population: a meta-analysis

Objective

To determine the association between the multidrug resistance 1 gene ( MDR1) C3435T polymorphism and adverse drug reactions in advanced non-small cell lung cancer (NSCLC) patients in Asia.

Methods

Literature about the relationship between the MDR1 C3435T polymorphism and adverse drug reactions in advanced NSCLC patients were collected from three English language databases (PubMed, Cochrane, and Embase) as well as three Chinese databases (Wanfang, China Knowledge Network, and the Chinese Biomedical Literature Database), and summarized by a meta-analysis.

Results

NSCLC patients with the T allele or TT genotype were significantly more likely to experience diarrhea than those with other genotypes under the allele model (odds ratio [OR] = 1.64, 95% confidence interval [CI]: 1.04–2.61), homozygous model (OR = 3.87, 95% CI: 1.49–10.07), and recessive model (OR = 4.48, 95% CI: 1.88–10.68). Similarly, these patients were significantly more likely to experience skin rash under the allele model (OR = 2.41, 95% CI: 1.24–4.66), homozygous model (OR = 4.77, 95% CI: 1.13–20.15), and dominant model (OR = 1.77, 95% CI: 1.03–3.05).

Conclusions

Asian NSCLC patients with the MDR1 C3435T T allele or TT genotype are significantly more likely to develop diarrhea and rash after drug treatment.

Major pitfalls of protein kinase inhibitors prescription: A review of their clinical pharmacology for daily use

Protein kinase inhibitors (PKI) are a growing class of anticancer agents. They are prescribed with flat doses, and their oral administration is associated with interindividual variability in exposure. Patients can be over- or underexposed, due to numerous factors. We reviewed key pharmacokinetic concepts and mechanisms by which PKIs prescription could be altered. Challenging situations that could lead to increased toxicity or to therapeutic failure are described and recommendation for clinicians are proposed. Finally, the interest of therapeutic drug monitoring and indications for its use in daily practice is discussed.

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.

Gefitinib exposure and occurrence of interstitial lung disease in Japanese patients with non-small-cell lung cancer

Purpose

A prospective, multicenter, large-scale cohort with a nested case–control study (NCT00252759) was conducted to identify and quantify risk factors for interstitial lung disease (ILD) in Japanese patients with non-small-cell lung cancer who received gefitinib. This study reports the association between gefitinib exposure and the occurrence of ILD.

Methods

A total of 1891 gefitinib plasma concentrations from 336 patients were measured after first dose, at steady state, and at time of ILD occurrence. Influences of demographic and pathophysiological factors on pharmacokinetics were investigated by non-linear mixed-effect modeling. The exposure to gefitinib was compared between patients without and with ILD occurrence to explore risks associated with gefitinib-induced ILD. Intra-patient comparison of exposure was also conducted between times at ILD development and normal states.

Results

In the population pharmacokinetic analysis for gefitinib, α₁-acid glycoprotein (AGP), age, body weight, and concomitant use of cytochrome P450 3A4 inducers were significant covariates on oral clearance (CL/F). AGP and body weight were also identified as factors affecting the volume of distribution. CL/F was significantly lower at the time of ILD occurrence than normal states. Patients who developed ILD tended to show higher exposure to gefitinib than those without ILD; however, these differences were not statistically significant. On the other hand, exposure at the time of ILD occurrence was significantly elevated compared to the time of normal state within the same patients.

Conclusions

Significant elevation of exposure of gefitinib was observed at the time of ILD occurrence, suggesting reduction of CL/F could be associated with ILD-induced AGP elevation. Increase in exposure of gefitinib is unlikely to be a robust predictor of ILD and does not warrant any dose modifications.

Electronic supplementary material

The online version of this article (10.1007/s00280-019-03788-4) contains supplementary material, which is available to authorized users.

[Personalized medicine for oral molecular-targeted anticancer drugs]

Therapeutic drug monitoring (TDM) is carried out by evaluating drug plasma (or serum) concentrations in response to individual optimal treatments by dose adjustment to improve efficacy or avoid side effects. Many molecular-targeted anticancer drugs show exposure-efficacy and exposure-toxicity relationships. Therefore, plasma concentrations of anticancer drugs can be used as biomarkers. However, to carry out TDM, therapeutic target ranges indicating exposure-response (efficacy/toxicity) relationships must be determined. In Japan, treatment fees for managing the TDM of imatinib and sunitinib have been assessed since 2012 and 2018, respectively. In therapy for imatinib or sunitinib using TDM, reduced toxicity, discontinuation rates, and costs for treatments as well as improved clinical efficacy have been noted. To establish the use of TDM in clinical practice, it is necessary to determine target plasma concentrations (minimum effective concentration or minimum toxic concentration) of many molecular-targeted anticancer drugs by retrospective and prospective clinical trials. In these clinical trials, analytical methods with high precision are needed. By carrying out TDM, we may determine the optimal anticancer therapy for patients as precision medicine after the start of therapy.

Development and validation of a method for gefitinib quantification in dried blood spots using liquid chromatography-tandem mass spectrometry: Application to finger-prick clinical blood samples of patients with non-small cell lung cancer

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of gefitinib in dried blood spots (DBSs). Gefitinib was extracted with methanol from DBS of 3 mm in diameter and detected using a triple quadrupole mass spectrometer. The method was validated by evaluating its precision, accuracy, selectivity, carryover, matrix effect, recovery, and stability. For clinical validation, paired finger-prick DBS and plasma concentrations were compared for 10 patients with non-small cell lung cancer (NSCLC) taking gefitinib. The calibration linear range was 37.5-2400 ng/mL (coefficient of determination [R²] = 0.99), encompassing the therapeutic concentrations of gefitinib. The accuracy and precision were within 15% of the quality control (QC) concentrations of 80, 200, and 2000 ng/mL. The lower limit of quantification was determined to be 40 ng/mL. Gefitinib was stable in DBSs for up to 5 months at room temperature and -20 °C, and at 40 °C for 24 h. A good correlation was observed between the gefitinib levels measured by the DBS method and plasma concentrations (R² = 0.99). This method provides a simple, fast, and accurate approach to the quantitative analysis of gefitinib in finger-prick DBSs. The method would be useful for minimally invasive evaluation of the clinical gefitinib blood concentration.

Factors affecting time to reach and recover from gefitinib-induced hepatotoxicity

Gefitinib is an oral tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR) for non-small-cell lung cancer with EGFR mutations. Although a few studies have analyzed the causes of gefitinib-induced hepatotoxicity, research focusing on the time intervals before and after hepatotoxicity has yet to be reported. Therefore, this study investigated two types of factors: the time to reach gefitinib-induced hepatotoxicity and the time for recovery. From January 2013 to December 2014, a retrospective study was carried out on 473 non-small-cell lung cancer patients who were treated with gefitinib. The following data were collected: sex, age, body weight, height, body surface area, underlying disease, Eastern Cooperative Oncology Group Performance Status, smoking history, gefitinib dose, EGFR mutation, and concomitant drugs. Multivariate models showed that patients with mutations in exon 19 had around two-fold higher hepatotoxicity (≥grade 2). Use of CYP3A4 inhibitors and smoking shortened time to hepatotoxicity ∼5-2-fold, respectively, whereas mutations in exon 21 prolonged time to hepatotoxicity by about 2.4-fold. Termination of gefitinib therapy showed 3.8-fold faster recovery. Our study showed that the concomitant use of CYP3A4 inhibitors, smoking, and exon 21 affected the time to reach gefitinib-induced hepatotoxicity. Among the factors examined in this study including hepatotonic use and gefitinib termination, only cessation of gefitinib therapy significantly accelerated recovery.

Associations between ABCG2 gene polymorphisms and gefitinib toxicity in non-small cell lung cancer: a meta-analysis

Background

Gefitinib is frequently used to treat patients with non-small cell lung cancer (NSCLC) and is excreted out from cells via the ATP-binding cassette transporter ABCG2. ABCG2 gene polymorphisms have been suggested to be associated with ABCG2 protein expression and function and may influence the risk of gefitinib toxicity in NSCLC patients. Previous studies on the associations between ABCG2 gene polymorphisms and the toxicity of gefitinib in NSCLC patients have produced conflicting results. The aim of this meta-analysis was to determine whether ABCG2 gene polymorphisms are associated with the risk of gefitinib-induced toxicity in NSCLC patients.

Methods

The PubMed and EMBASE databases were searched systematically for all eligible studies. A relative risk with corresponding 95% CI was calculated to evaluate the associations between ABCG2 gene polymorphisms and gefitinib-induced toxicity.

Results

Data were finally extracted from seven studies and 515 patients were found to meet the inclusion criteria of the meta-analysis. A dominant model showed that there was no significant association between the ABCG2 C421A polymorphism and the risk of gefitinib-induced toxicity, while the ABCG2 G34A polymorphism might be associated with an increased risk of skin toxicity in gefitinib therapy (relative risk =1.54, 95% CI 1.08-2.21, P=0.02). However, more reliable data are required to confirm the associations between the ABCG2 C421A and ABCG2 G34A polymorphisms and the toxicity of gefitinib in NSCLC patients.

Conclusion

While the ABCG2 C421A polymorphism might not be a reliable marker of gefitinib-related toxicity, the ABCG2 G34A genotype may be predictive of the skin toxicity of gefitinib in NSCLC patients. These conclusions need to be verified in further large-scale studies.

Effect of Paclitaxel-Mesoporous Silica Nanoparticles with a Core-Shell Structure on the Human Lung Cancer Cell Line A549

A nanodrug delivery system of paclitaxel-mesoporous silica nanoparticles with a core-shell structure (PAC-csMSN) was used to increase the dissolution of paclitaxel (PAC) and improve its treatment of lung cancer. PAC was loaded into the core-shell mesoporous silica nanoparticles (csMSN) by the adsorption equilibrium method and was in an amorphous state in terms of its mesoporous structure. In vitro and in vivo studies showed that csMSN increased the dissolution rate of PAC and improved its lung absorption. The area under concentration-time curve (AUC) value of PAC-csMSN used for pulmonary delivery in rabbits was 2.678-fold higher than that obtained with the PAC. After continuous administration for 3 days, a lung biopsy showed no signs of inflammation. Cell apoptosis results obtained by flow cytometry indicated that PAC-csMSN was more potent than pure PAC in promoting cell apoptosis. An absorption investigation of PAC-csMSN in A549 cells was carried out by transmission electron microscopy (TEM) and laser scanning confocal microscopy (LSCM). The obtained results indicated that the cellular uptake was time-dependent and csMSN was uptaken into the cytoplasm. All these results demonstrate that csMSN have the potential to achieve pulmonary inhalation administration of poorly water-soluble drugs for the treatment of lung cancer.

BCRP/ABCG2 and high-alert medications: Biochemical, pharmacokinetic, pharmacogenetic, and clinical implications

The human breast cancer resistance protein (BCRP/ABCG2) is an ATP-binding cassette efflux transporter that uses ATP hydrolysis to expel xenobiotics from cells, including anti-cancer medications. It is expressed in the gastrointestinal tract, liver, kidney, and brain endothelium. Thus, ABCG2 functions as a tissue barrier to drug transport that strongly influences the pharmacokinetics of substrate medications. Genetic polymorphisms of ABCG2 are closely related to inter-individual variations in therapeutic performance. The common single nucleotide polymorphism c.421C>A, p.Q141K reduces cell surface expression of ABCG2 protein, resulting in lower efflux of substrates. Consequently, a higher plasma concentration of substrate is observed in patients carrying an ABCG2 c.421C>A allele. Detailed pharmacokinetic analyses have revealed that altered intestinal absorption is responsible for the distinct pharmacokinetics of ABCG2 substrates in genetic carriers of the ABCG2 c.421C>A polymorphism. Recent studies have focused on the high-alert medications among ABCG2 substrates (defined as those with high risk of adverse events), such as tyrosine kinase inhibitors (TKIs) and direct oral anti-coagulants (DOACs). For these high-alert medications, inter-individual variation may be closely related to the severity of side effects. In addition, ethnic differences in the frequency of ABCG2 c.421C>A have been reported, with markedly higher frequency in East Asian (∼30-60%) than Caucasian and African-American populations (∼5-10%). Therefore, ABCG2 polymorphisms must be considered not only in the drug development phase, but also in clinical practice. In the present review, we provide an update of basic and clinical knowledge on genetic polymorphisms of ABCG2.

Practical Recommendations for Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Despite the fact that pharmacokinetic exposure of kinase inhibitors (KIs) is highly variable and clear relationships exist between exposure and treatment outcomes, fixed dosing is still standard practice. This review aims to summarize the available clinical pharmacokinetic and pharmacodynamic data into practical guidelines for individualized dosing of KIs through therapeutic drug monitoring (TDM). Additionally, we provide an overview of prospective TDM trials and discuss the future steps needed for further implementation of TDM of KIs.

Low plasma concentration of gefitinib in patients with EGFR exon 21 L858R point mutations shortens progression-free survival

PURPOSE

The relationship between the pharmacokinetics and effects of gefitinib in patients with epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) is unknown. In this study, we examined the correlation between gefitinib plasma concentration and progression-free survival (PFS) in patients with two common types of EGFR mutations: a deletion in exon 19 and point mutations in exon 21 L858R.

METHODS

The retrospective analysis examined 40 patients who were administered 250 mg of gefitinib daily. All patients were diagnosed with and treated for advanced non-small cell lung carcinoma with sensitive EGFR mutations between January 2011 and November 2013 at Akita University Hospital, Akita, Japan. The 40 patients were divided into four groups by trough plasma concentration (high or low) and mutation type (exon 19 deletions or exon 21 L858R point mutations). PFS, response rate, and toxic effects were analyzed in all four groups.

RESULTS

After excluding 5 patients, the remaining 35 were successfully analyzed. For the patients with exon 19 deletions, there was no significant difference in PFS between the high and low plasma concentration groups (median survival: 12.0 vs. 17.0 months, P = 0.9548). In contrast, the PFS was significantly shorter for patients with exon 21 point mutations and low vs. high concentrations of gefitinib (median survival: 8.0 vs. 16.0 months, P < 0.05).

CONCLUSIONS

The results suggest that low gefitinib plasma concentrations in patients with exon 21 L858R point mutations may be associated with shorter PFS in NSCLC patients.

Genotypes Affecting the Pharmacokinetics of Anticancer Drugs

Cancer treatment is becoming more and more individually based as a result of the large inter-individual differences that exist in treatment outcome and toxicity when patients are treated using population-based drug doses. Polymorphisms in genes encoding drug-metabolizing enzymes and transporters can significantly influence uptake, metabolism, and elimination of anticancer drugs. As a result, the altered pharmacokinetics can greatly influence drug efficacy and toxicity. Pharmacogenetic screening and/or drug-specific phenotyping of cancer patients eligible for treatment with chemotherapeutic drugs, prior to the start of anticancer treatment, can identify patients with tumors that are likely to be responsive or resistant to the proposed drugs. Similarly, the identification of patients with an increased risk of developing toxicity would allow either dose adaptation or the application of other targeted therapies. This review focuses on the role of genetic polymorphisms significantly altering the pharmacokinetics of anticancer drugs. Polymorphisms in DPYD, TPMT, and UGT1A1 have been described that have a major impact on the pharmacokinetics of 5-fluorouracil, mercaptopurine, and irinotecan, respectively. For other drugs, however, the association of polymorphisms with pharmacokinetics is less clear. To date, the influence of genetic variations on the pharmacokinetics of the increasingly used monoclonal antibodies has hardly been investigated. Some studies indicate that genes encoding the Fcγ-receptor family are of interest, but more research is needed to establish if screening before the start of therapy is beneficial. Considering the profound impact of polymorphisms in drug transporters and drug-metabolizing enzymes on the pharmacokinetics of chemotherapeutic drugs and hence, their toxicity and efficacy, pharmacogenetic and pharmacokinetic profiling should become the standard of care.

Association of axitinib plasma exposure and genetic polymorphisms of ABC transporters with axitinib-induced toxicities in patients with renal cell carcinoma

PURPOSE

Axitinib is a selective tyrosine kinase inhibitor of VEGF receptors, approved for advanced renal cell carcinoma (RCC). Associations between axitinib plasma exposure, genetic polymorphisms of ABC transporters and axitinib-induced toxicities have not been adequately explored.

METHODS

Twenty RCC patients treated with axitinib were enrolled in this study. Blood samples were collected 0, 0.5, 1, 2, 4, and 6 h after administration of axitinib on day 1 and at steady state. Plasma concentrations of axitinib were analyzed by UPLC-MS/MS. The ABCG2 (421C>A) and ABCB1 (1236C>T, 2677G>T/A, 3435C>T) genetic polymorphisms were determined by real-time PCR.

RESULTS

ABCB1 haplotype was associated with increased dose-adjusted area under the plasma concentration-time curve (AUC) of axitinib at steady state. The incidence of fatigue during therapy was associated with high AUC0-6 of axitinib (P = 0.013). The treatment period without discontinuation or dose reduction due to adverse events in patients with high AUC0-6 of axitinib was significantly shorter than for those with low AUC0-6 (P = 0.024). No significant differences were found in the frequency of adverse events among the ABCG2 genotype and ABCB1 haplotype groups.

CONCLUSIONS

Our results have demonstrated that adverse events leading to discontinuation or dose reduction in axitinib were associated with increased axitinib plasma exposure, but not directly with genetic polymorphisms of ABC transporters. Therefore, measurement of steady state axitinib plasma concentrations may be useful in avoiding adverse events in axitinib therapy.

Efflux transporter variants as predictors of drug toxicity in lung cancer patients: systematic review and meta-analysis

Chemotherapeutic drugs are underutilized in lung cancer management due in part to serious adverse drug reactions (ADRs).

AIM

With studies revealing an association between interindividual patient ADR variation and efflux transporter variants, we carried out a meta-analysis and systemic review, in order to highlight current knowledge regarding the strength of association between efflux transporter SNPs variants and chemotherapeutic-drug induced ADRs.

MATERIALS & METHODS

Papers were sourced from MEDLINE, Cochrane Library, CINHL, EMBASE, Web of Knowledge, Scopus. The Cochrane Collaboration Risk of Bias Tool v13 was used to evaluate six types of bias domains for each of the publications reviewed.

RESULTS

Twenty-five publications comprising three randomised control trials, two retrospective case-controls and 20 clinical observation studies, totalling 3578 patients, were deemed eligible for review. Of the known efflux drug transporters, we report findings on the ABC members ABCB1, ABCC1, ABCC2, ABCG2, ABCA1, ABCC4 and ABCC5. Meta-analysis showed an decreased risk of irinotecan-induced neutropenia in patients expressing ABCB1 2677G>T/G (odds ratio [OR]: 0.24; 95% CI: 0.1-0.59; p = 0.002) but increased risk for ABCC2 3972T>T (OR: 1.67; 95% CI: 1.01-2.74; p = 0.04). ABCG2 34G>A was associated with a threefold increased risk of irinotecan-induced diarrhea (95% CI: 1.00-6.24; p = 0.05).

CONCLUSION

The majority of studies have identified a role for variants in effluxdrug transporters in contributing to lung cancer treatment-associated ADRs. However, for implementation of use of these transporter genetic variants as prognostic markers for ADR risk, future studies must incorporate larger patient numbers.

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.

Genetic Association of Curative and Adverse Reactions to Tyrosine Kinase Inhibitors in Chinese advanced Non-Small Cell Lung Cancer patients

Epidermal growth factor receptor (EGFR) Tyrosine kinase inhibitor (TKI) is an effective targeted therapy for advanced non-small cell lung cancer (NSCLC) but also causes adverse drug reactions (ADRs) e.g., skin rash and diarrhea. SNPs in the EGFR signal pathway, drug metabolism/ transport pathways and miRNA might contribute to the interpersonal difference in ADRs but biomarkers for therapeutic responses and ADRs to TKIs in Chinese population are yet to be fully investigated. We recruited 226 Chinese advanced NSCLC patients who received TKIs erlotinib, gefitinib and icotinib hydrochloride and systematically studied the genetic factors associated with therapeutic responses and ADRs. Rs884225 (T > C) in EGFR 3' UTR was significantly associated with lower risk of ADRs to erlotinib (p value = 0.0010, adjusted p value = 0.042). A multivariant interaction four-SNP model (rs884225 in EGFR 3'UTR, rs7787082 in ABCB1 intron, rs38845 in MET intron and rs3803300 in AKT1 5'UTR) was associated with ADRs in general and the more specific drug induced skin injury. The SNPs associated with both therapeutic responses and ADRs indicates they might share a common genetic basis. Our study provided potential biomarkers and clues for further research of biomarkers for therapeutic responses and ADRs in Chinese NSCLC patients.

Pulmonary Toxicities of Gefitinib in Patients With Advanced Non-Small-Cell Lung Cancer: A Meta-Analysis of Randomized Controlled Trials

Gefitinib is a selective tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR) used to treat adults with EGFR mutation-positive non-small-cell lung cancer (NSCLC). Clinical benefits of gefitinib administration in NSCLC patients have been observed in clinical practice, but the extent of the pulmonary toxicity of gefitinib in patients with advanced NSCLC remains unclear. The aim of this systematic review was to evaluate the overall incidence and risk of gefitinib-related pulmonary toxicity in advanced NSCLC patients. Relevant trials were identified from the databases of Pubmed, Embase, Cochrane Library, and the clinicaltrials.gov of the U.S. National Institutes of Health. The outcomes included the overall incidence, odds ratios (ORs), and 95% confidence intervals (CIs). Fixed-effects models were used in the statistical analyses according to the heterogeneity of the included studies. According to the data from the included trials, the overall incidence of high-grade hemoptysis, pneumonia, pneumonitis, and interstitial lung disease (ILD) was 0.49% (95% CI: 0.24%-0.99%), 2.33% (95% CI: 1.47%-3.66%), 2.24% (95% CI: 1.34%-3.72%), and 1.43% (95% CI: 0.98%-2.09%), respectively. The pooled ORs of high-grade hemoptysis, pneumonia, pneumonitis, and ILD were 1.73 (95% CI: 0.46-6.52; P = 0.42), 0.99 (95% CI: 0.66-1.49; P = 0.95), 4.70 (95% CI: 1.48-14.95; P = 0.0087), and 2.64 (95% CI: 1.22-5.69; P = 0.01), respectively. Gefitinib was associated with a significantly increased risk of high-grade/fatal ILD and pneumonitis compared with the controls, whereas the risk of other high-grade pulmonary events (pneumonia and hemoptysis) was not significant. Careful surveillance of gefitinib-related pulmonary toxicity is critical for the safe use of this drug.

Association of pharmacokinetics and pharmacogenomics with safety and efficacy of gefitinib in patients with EGFR mutation positive advanced non-small cell lung cancer

OBJECTIVES

Gefitinib is a potent epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor and is a key drug for patients with EGFR mutation-positive advanced non-small cell lung cancer (NSCLC). The pharmacokinetics of orally administered gefitinib varies greatly among patients. We prospectively evaluated the association of pharmacokinetics and pharmacogenomics with the safety and efficacy of gefitinib in patients with EGFR mutation-positive advanced NSCLC.

PATIENTS AND METHODS

Pharmacokinetics was evaluated with samples of peripheral blood obtained on day 1 before treatment and 1, 3, 5, 8, and 24h after gefitinib (250 mg per day) was administered and on days 8 and 15 as the trough values. The plasma concentration of gefitinib was analyzed with high-performance liquid chromatography. The genotypes of ABCG2, ABCB1, CYP3A4, CYP3A5, and CYP2D6 genes were analyzed with direct sequencing.

RESULTS

The subjects were 35 patients (21 women; median age, 72 years; range, 53 to 90 years) with stage IV adenocarcinoma harboring EGFR mutations. The median peak plasma concentration (Cmax) was 377 (range, 168-781)ng/mL. The median area under the curve (AUC) of the plasma concentration of gefitinib from 0 to 24h was 4893 (range, 698-13991) ng/mL h. The common adverse events were skin toxicity (68% of patients), diarrhea (46%), and liver injury (63%). One patient died of drug-induced interstitial lung disease (ILD). The overall response rate was 82.9% (95% confidence interval, 66.4%-93.4%). The median progression-free survival time was 10 months, and the median survival time was 25 months. The pharmacokinetics and pharmacogenomics were not associated with significantly different toxicities, response rates, or survival times with gefitinib. However, the AUC and Cmax were highest and the trough value on day 8 was the second highest in one patient who died of drug-induced ILD.

CONCLUSION

Elevated gefitinib exposure might be associated with drug-induced ILD.