Metabolism-related pharmacokinetic drug-drug interactions with tyrosine kinase inhibitors: current understanding, challenges and recommendations

Drug-Drug Interactions and Pharmacogenomic Evaluation in Colorectal Cancer Patients: The New Drug-PIN® System Comprehensive Approach

Drug–drug interactions (DDIs) can affect both treatment efficacy and toxicity. We used Drug-PIN^® (Personalized Interactions Network) software in colorectal cancer (CRC) patients to evaluate drug–drug–gene interactions (DDGIs), defined as the combination of DDIs and individual genetic polymorphisms. Inclusion criteria were: (i) stage II-IV CRC; (ii) ECOG PS (Performance status sec. Eastern coperative oncology group) ≤2; (iii) ≥5 concomitant drugs; and (iv) adequate renal, hepatic, and bone marrow function. The Drug-PIN^® system analyzes interactions between active and/or pro-drug forms by integrating biochemical, demographic, and genomic data from 110 SNPs. We selected DDI, DrugPin1, and DrugPin2 scores, resulting from concomitant medication interactions, concomitant medications, and SNP profiles, and DrugPin1 added to chemotherapy drugs, respectively. Thirty-four patients, taking a median of seven concomitant medications, were included. The median DrugPin1 and DrugPin2 scores were 42.6 and 77.7, respectively. In 13 patients, the DrugPin2 score was two-fold higher than the DrugPin1 score, with 7 (54%) of these patients experiencing severe toxicity that required hospitalization. On chi-squared testing for any toxicity, a doubled DrugPin2 score (p = 0.001) was significantly related to G3–G4 toxicity. Drug-PIN^® software may prevent severe adverse events, decrease hospitalizations, and improve survival in cancer patients.

Assessment of Herb-drug Interactions Based on the Pharmacokinetic Changes of Probe Drug, Midazolam

BACKGROUND

In healthy volunteers, the probe drug method is widely practised to assess the pharmacokinetic mediated herb-drug interactions (HDI). We analyzed the clinical evidence of CYP3 A4 probe drug, Midazolam.

METHODS

Literatures, where Midazolam was used as a probe drug for prediction of herb-drug interaction, were surveyed through an online database such as google scholar, Scopus, Cochrane, PubMed and clinicaltrials.gov.

RESULTS

Midazolam was considered a sensitive probe for CYP3A4 substrates due to its bioavailability. We observed that not all the herbs are causing drug interaction. However, significant changes of the Midazolam pharmacokinetics were found after high-dose and long-term intake of some herbs and food supplements, suggesting the induction and/or inhibition of CYP activities.

CONCLUSION

Probe drug technique is one of the easiest ways for predicting CYP enzyme-mediated herb-drug interactions. Midazolam shows a good response in clinical studies because of short halflife and low harmfulness compared with other probe drugs.

Pharmacokinetic drug–drug interactions: an insight into recent US FDA-approved drugs for prostate cancer

Pharmacokinetic drug–drug interaction is a significant safety and efficiency concern as it results in considerable concentration changes. Drug–drug interactions are a substantial concern in anticancer drugs that possess a narrow therapeutic index. These interactions remain as the principal regulatory obstacle that can lead to termination in the preclinical stage, restrictions in the prescription, dosage adjustments or withdrawal of the drugs from the market. Drug metabolizing enzymes or transporters mediate the majority of clinically relevant drug interactions. Cancer diagnosed aged patients use multiple medications and are more prone to significant drug–drug interactions. This review provides detailed information on clinically relevant drug–drug interactions resulting from drug metabolism by enzymes and transporters with a particular emphasis on recent FDA approved antiprostate cancer drugs.

A Short Exploration of Selected Sensitive CYP3A4 Substrates (Probe Drug)

BACKGROUND

CYP450 enzymes in the liver have a significant role in the metabolism of xenobiotics. Probe drug strategy is broadly used to evaluate the pharmacodynamic and pharmacokinetic drug/ herb-drug interactions/ food-drug interactions. Probe drugs reveal the exact pathway of drug metabolism in the liver by their targeted tractability property. The CYP3A4 isoenzyme metabolizes the majority of the drugs (65%).

METHODS

The characteristics of targeted probe drugs were observed from the admetSAR (version2) online database.

RESULTS

Midazolam is widely used as a probe drug because of its peculiar character. Midazolam affirms the accurate and consistent prediction of pharmacokinetic mediated drug interactions even in nanogram concentrations with or without a potent CYP3A inhibitor. Remarkably, midazolam is used as a CYP3A4 substrate in the majority of in vivo studies.

CONCLUSION

It is concluded that midazolam shows a good response in all clinical studies because of its lesser half-life and bioavailability when compared with other probe drugs.

Practical Application of "About Herbs" Website: Herbs and Dietary Supplement Use in Oncology Settings

The Integrative Medicine Service at Memorial Sloan Kettering Cancer Center developed and maintains About Herbs (www.aboutherbs.com), which provides summaries of research data including purported uses, adverse effects, and herb-drug interactions for about 284 dietary supplements. Using Google Analytics, we found the website registered more than 26,317,000 hits since November 2002. The 10 most searched-for herbs/supplements of 2018 are chaga mushroom, turmeric, ashwagandha, reishi mushroom, graviola, Active Hexose-Correlated Compound, boswellia, dandelion, green tea, and Coriolus versicolor. Here we discuss their safety, herb-drug interactions, and appropriate uses in the oncology setting, based on literature searches in PubMed. Over the past 16 years, the evidence for use of these supplements is based mostly on preclinical findings, with few well-designed studies and limited trials conducted in cancer patients. It is important to familiarize health care professionals about popular supplements, so patients can be informed to make decisions that maximize benefits and minimize risks.

Clinical usefulness of very high serum soluble interleukin-2 receptor levels for the detection of tuberculous peritonitis in a patient with chronic myelogenous leukemia

Tuberculous peritonitis is difficult to diagnose due to the disadvantages of ascitic culture and peritoneal biopsy. Although previous reports suggested that very high serum soluble interleukin-2 receptor (sIL-2R) levels may reflect the clinical activity of tuberculosis, little is known about the diagnostic utility of serum sIL-2R for tuberculous peritonitis. We describe a case of tuberculous peritonitis with chronic myelogenous leukemia. The abnormally high serum sIL-2R value and negative findings for other possible causes including lymphoma suggested tuberculous peritonitis and we administered anti-tuberculosis treatment before definitive diagnosis. Abnormally high serum sIL-2R levels may contribute to earlier diagnosis of tuberculous peritonitis, along with ruling out other potential differential diagnoses.

Oral Anticancer Therapy: Management of Drug Interactions

Oral anticancer therapy is increasingly integrated into the care of patients with cancer. Recognition and management of drug-drug interactions (DDIs) is critical to providing efficacious and safe anticancer treatment. DDIs with QTc-prolonging agents, anticoagulants, enzyme inducers and inhibitors, antidepressants, and acid suppressants are commonly encountered with anticancer therapies. Here, we review frequently observed DDIs and outline literature-supported suggestions for their management.

Overcoming Resistance to FLT3 Inhibitors in the Treatment of FLT3-Mutated AML

Acute myeloid leukaemia (AML) carrying internal tandem duplication (ITD) of Fms-Like Tyrosine kinase 3 (FLT3) gene is associated with high risk of relapse and poor clinical outcome upon treatment with conventional chemotherapy. FLT3 inhibitors have been approved for the treatment of this AML subtype but leukaemia relapse remains to be a major cause of treatment failure. Mechanisms of drug resistance have been proposed, including evolution of resistant leukaemic clones; adaptive cellular mechanisms and a protective leukaemic microenvironment. These models have provided important leads that may inform design of clinical trials. Clinically, FLT3 inhibitors in combination with conventional chemotherapy as induction treatment for fit patients; with low-intensity treatment as salvage treatment or induction for unfit patients as well as maintenance treatment with FLT3 inhibitors post HSCT hold promise to improve survival in this AML subtype.

Optimizing treatment of renal cell carcinoma with VEGFR-TKIs: a comparison of clinical pharmacology and drug-drug interactions of anti-angiogenic drugs

Anti-angiogenic treatment is an important option that has changed the therapeutic landscape in various tumors, particularly in patients affected by renal cell carcinoma (RCC). Agents that block signaling pathways governing tumor angiogenesis have raised high expectations among clinicians. Vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) comprise a heterogeneous class of drugs with distinct pharmacological profiles, including potency, selectivity, pharmacokinetics and drug-drug interactions. Among them, tivozanib is one of the last TKIs introduced in the clinical practice; this drug selectively targets VEGFRs, it is characterized by a favorable pharmacokinetics and safety profile and has been approved as first-line treatment for patients with metastatic RCC (mRCC). In this article, we describe the clinical pharmacology of selected VEGFR-TKIs used for the treatment of mRCC, highlighting the relevant differences; moreover we aim to define the main pharmacologic characteristics of these drug.

Pharmacogenomics at the center of precision medicine: challenges and perspective in an era of Big Data

Pharmacogenomics (PGx) is one of the core elements of personalized medicine. PGx information reduces the likelihood of adverse drug reactions and optimizes therapeutic efficacy. St Catherine Specialty Hospital in Zagreb/Zabok, Croatia has implemented a personalized patient approach using the RightMed^® Comprehensive PGx panel of 25 pharmacogenes plus Facor V Leiden, Factor II and MTHFR genes, which is interpreted by a special counseling team to offer the best quality of care. With the advent of significant technological advances comes another challenge: how can we harness the data to inform clinically actionable measures and how can we use it to develop better predictive risk models? We propose to apply the principles artificial intelligence to develop a medication optimization platform to prevent, manage and treat different diseases.

The Other Obesity Epidemic-Of Drugs and Bugs

Chronic psychiatric patients with schizophrenia and related disorders are frequently treatment-resistant and may require higher doses of psychotropic drugs to remain stable. Prolonged exposure to these agents increases the risk of weight gain and cardiometabolic disorders, leading to poorer outcomes and higher medical cost. It is well-established that obesity has reached epidemic proportions throughout the world, however it is less known that its rates are two to three times higher in mentally ill patients compared to the general population. Psychotropic drugs have emerged as a major cause of weight gain, pointing to an urgent need for novel interventions to attenuate this unintended consequence. Recently, the gut microbial community has been linked to psychotropic drugs-induced obesity as these agents were found to possess antimicrobial properties and trigger intestinal dysbiosis, depleting Bacteroidetes phylum. Since germ-free animals exposed to psychotropics have not demonstrated weight gain, altered commensal flora composition is believed to be necessary and sufficient to induce dysmetabolism. Conversely, not only do psychotropics disrupt the composition of gut microbiota but the later alter the metabolism of the former. Here we review the role of gut bacterial community in psychotropic drugs metabolism and dysbiosis. We discuss potential biomarkers reflecting the status of Bacteroidetes phylum and take a closer look at nutritional interventions, fecal microbiota transplantation, and transcranial magnetic stimulation, strategies that may lower obesity rates in chronic psychiatric patients.

Is there truly an increase in risk of cardiovascular and hematological adverse events with vascular endothelial growth factor receptor tyrosine kinase inhibitors?

Objectives: Recent studies have shown an increase risk of cardiovascular and hematological adverse events associated with vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs). The authors hypothesize that the original studies may have produced exaggerated results because of the small baseline risks involved.Methods: A meta-analysis that included 71 trials, 8 different VEGFR-TKIs, and 11 adverse events were re-analyzed. The outcome of interest was re-defined as the complementary outcome (i.e. remaining free of an adverse event). The inverse variance heterogeneity model was used to pool the effect size.Results: VEGFR-TKIs decreased the risk of remaining free of hypertension by 7% (RR 0.93; 95%CI:0.88-0.97). Specific VEGFR-TKIs; pazopanib, regorafenib, and nintedanib were associated with a decrease risk of remaining free of an arterial thrombotic event (RR 0.96; 95%CI:0.93-0.99), thrombocytopenia (RR 0.91; 95%CI:0.89-0.93), and bleeding (RR 0.96; 95%CI:0.93-0.99) respectively. VEGFR-TKIs were not associated with the thrombotic event, myocardial infarction, stroke, venous thrombotic event, pulmonary embolism, left ventricular dysfunction, or QTc interval prolongation.Conclusion: VEGFR-TKIs are associated with a small increase in the risk of patients developing hypertension, arterial thrombotic events, thrombocytopenia, and bleeding. Previous studies overestimated the actual risk associated with VEGFR-TKIs by analyzing the outcome with the lower baseline risk.

Onco-cardiology: Drug-drug interactions of antineoplastic and cardiovascular drugs

Cardiovascular diseases (CVD) and cancer are still the leading causes of death. There are many common etiologic factors, especially smoking and obesity. Therefore, it is not uncommon for CVD and cancer to coexist. Drug-drug interactions (DDIs) inevitably occur in this group of patients, where polypharmacy is increasing due to older age and multiple comorbidities. However, multidisciplinary studies, especially close collaboration of medical oncologists and cardiologists, who deals with the diagnosis and treatment of these diseases, awareness and preventive approaches to DDIs may reduce serious morbidity and mortality. In this review, information about the common treatments used in cardiology and oncology and possible DDIs are discussed.

Impact of Disease and Treatment Response in Drug-Drug Interaction Studies: Osimertinib and Simvastatin in Advanced Non-Small Cell Lung Cancer

A phase I, open‐label study (NCT02197234) assessed the effects of osimertinib on simvastatin exposure in patients with advanced epidermal growth factor receptor (EGFR)‐mutated non‐small cell lung cancer and disease progression post‐EGFR tyrosine kinase inhibitor treatment. Here, we report on a retrospective analysis of two patients (patients 1 and 2) who had liver metastases and high simvastatin exposure prior to osimertinib treatment, which changed following treatment. Patients received single oral doses of simvastatin 40 mg on day (D) 1 and D31, and osimertinib 80 mg once daily on D3–32. At baseline, both patients had abnormal liver function tests (LFTs; Child‐Pugh scores of 6 and 8, respectively), significant liver metastasis, and, after a single simvastatin dose, had higher (~ 10‐fold) exposure compared with all other patients. Following 31 days of continuous osimertinib treatment, simvastatin exposures (area under the plasma concentration‐time curve from zero to infinity (AUC) and maximum plasma concentration (C_max)) and LFTs, such as alanine transaminase, aspartate aminotransferase, and bilirubin normalized to population mean values. Additionally, ~ 50% and ~ 80% reductions in liver metastases were observed on computed tomography scans in patients 1 and 2, respectively. High simvastatin exposure on D1 likely resulted from impairment of hepatic first pass metabolism due to liver metastases. Reduction in hepatic disease burden due to osimertinib treatment likely resulted in liver function returning to normal levels.

Theoretical study on the mechanism of N- and α-carbon oxidation of lapatinib catalyzed by cytochrome P450 monooxygenase

Lapatinib, an orally active dual tyrosine kinase inhibitor, is efficacious in combination therapy with capecitabine for advanced metastatic breast cancer. Despite its importance, it has been associated with hepatotoxicity observed in clinical trials and postmarketing surveillance. The mechanisms of hepatotoxicity at the chemical and cellular levels may link to drug metabolism. In this study, the N- and α-carbon oxidation processes of lapatinib catalyzed by CYP3A4 were explored by density functional theory method. The calculation results show that oxidation of C₆ is the primary metabolic process and carboxylic acid is the main metabolic product. Both hydroxylation of C₈ and subsequent formation of primary amines are feasible. However, it is not easy for the primary amines to form active metabolites nitroso, which indicates that there are other paths for the production of nitroso. Carboxylic acid is not the main metabolite of N₇ oxidation because of higher hydrolysis energy barrier of intermediate nitrone. It is worthy to study subsequent N-hydroxylation and its downstream reaction, which may be the main pathway for the formation of nitroso. These results lay the foundation for drug design and optimization.

Herb-drug interactions: a novel algorithm-assisted information system for pharmacokinetic drug interactions with herbal supplements in cancer treatment

PURPOSE

To develop a system to estimate the risk of herb-drug interactions that includes the available evidence from clinical and laboratory studies, transparently delineates the algorithm for the risk estimation, could be used in practice settings and allows for adaptation and update.

METHODS

We systematically searched Drugbank, Transformer, Drug Information Handbook, European and German Pharmacopoeia and MEDLINE for studies on herb-drug interactions of five common medicinal plants (coneflower, ginseng, milk thistle, mistletoe and St. John's wort). A diverse set of data were independently extracted by two researchers and subsequently analysed by a newly developed algorithm. Results are displayed in the form of interaction risk categories. The development of the algorithm was guided by an expert panel consensus process.

RESULTS

From 882 publications retrieved by the search, 154 studies were eligible and provided 529 data sets on herbal interactions. The developed algorithm prioritises results from clinical trials over case reports over in vitro investigations and considers type of study, consistency of study results and study outcome for clinical trials as well as identification, permeability, bioavailability, and interaction potency of an identified herbal perpetrator for in vitro investigations. Risk categories were assigned to and dynamically visualised in a colour-coded matrix format.

CONCLUSIONS

The novel algorithm allows to transparently generate and dynamically display herb-drug interaction risks based on the available evidence from clinical and laboratory pharmacologic studies. It provides health professionals with readily available and easy updatable information about the risk of pharmacokinetic interactions between herbs and oncologic drugs.

Modulation of Fexofenadine Pharmacokinetics by Osimertinib in Patients With Advanced EGFR-Mutated Non-Small Cell Lung Cancer

Osimertinib is a potent, third-generation, irreversible, central nervous system active epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) that selectively inhibits EGFR-TKI sensitizing and EGFR T790M resistance mutations. It is approved for first-line treatment of patients with advanced non-small cell lung cancer (NSCLC) whose tumors have EGFR exon 19 deletions or exon 21 L858R mutations, and for patients with T790M-positive advanced NSCLC whose disease has progressed on or after EGFR-TKI therapy. This study investigated the pharmacokinetics (PK) of fexofenadine (P-glycoprotein substrate) following single- and multiple-dose osimertinib in patients with advanced NSCLC who have progressed on prior EGFR-TKI therapy. This open-label, phase 1 study (NCT02908750) comprised the PK phase and continued access phase. The former comprised 2 distinct periods with a 3- to 7-day washout: treatment period 1 (n = 24, fexofenadine 120 mg, day 1) and treatment period 2 (fexofenadine 120 mg + osimertinib 80 mg single dose on days 1 and 39 and osimertinib 80 mg once daily from days 4 to 41). Patients could continue osimertinib 80 mg once daily based on investigator's discretion in the continued access phase. Fexofenadine area under the plasma concentration-time curve and maximum concentration increased by 56% (90% confidence interval [CI], 35.4-78.6) and 76% (90%CI, 49.3-108.3) following coadministration with osimertinib single dose, and by 27% (90%CI, 11.2-45.8) and 25% (90%CI, 5.6-48.1) when given with osimertinib at steady state, respectively. Following osimertinib coadministration, median fexofenadine time to maximum concentration increased by approximately 30 minutes compared with time to maximum concentration following fexofenadine alone. No new osimertinib safety findings were observed. The increase in fexofenadine exposure following osimertinib coadministration shows osimertinib as a weak P-glycoprotein inhibitor.

Integrating the Epigenome to Identify Drivers of Hepatocellular Carcinoma

Disruption of epigenetic mechanisms has been intimately linked to the etiology of human cancer. Understanding how these epigenetic mechanisms (including DNA methylation [5mC], hydroxymethylation [5hmC], and histone post-translational modifications) work in concert to drive cancer initiation and progression remains unknown. Hepatocellular carcinoma (HCC) is increasing in frequency in Western countries but lacks efficacious treatments. The epigenome of HCC remains understudied. To better understand the epigenetic underpinnings of HCC, we performed a genome-wide assessment of 5mC, 5hmC, four histone modifications linked to promoter/enhancer function (H3K4me1, H3K27ac, H3K4me3, and H3K27me3), and transcription across normal, cirrhotic, and HCC liver tissue. Implementation of bioinformatic strategies integrated these epigenetic marks with each other and with transcription to provide a comprehensive epigenetic profile of how and when the liver epigenome is perturbed during progression to HCC. Our data demonstrate significant deregulation of epigenetic regulators combined with disruptions in the epigenome hallmarked by profound loss of 5hmC, locus-specific gains in 5mC and 5hmC, and markedly altered histone modification profiles, particularly remodeling of enhancers. Data integration demonstrates that these marks collaborate to influence transcription (e.g., hyper-5hmC in HCC-gained active enhancers is linked to elevated expression) of genes regulating HCC proliferation. Two such putative epigenetic driver loci identified through our integrative approach, COMT and FMO3, increase apoptosis and decrease cell viability in liver-derived cancer cell lines when ectopically re-expressed. Conclusion: Altogether, integration of multiple epigenetic parameters is a powerful tool for identifying epigenetically regulated drivers of HCC and elucidating how epigenome deregulation contributes to liver disease and HCC.

Is there adaptation in the human genome for taste perception and phase I biotransformation?

Background

During the modern human expansion, new environmental pressures may have driven adaptation, especially in genes related to the perception of ingested substances and their detoxification. Consequently, positive (adaptive) selection may have occurred in genes related to taste, and in those related to the CYP450 system due to its role in biotransformation of potentially toxic compounds. A total of 91 genes (taste receptors and CYP450 superfamily) have been studied using Hierarchical Boosting, a powerful combination of different selection tests, to detect signatures of recent positive selection in three continental human populations: Northern Europeans (CEU), East Asians (CHB) and Africans (YRI). Analyses have been refined with selection analyses of the 26 populations of 1000 Genomes Project Phase 3.

Results

Genes related to taste perception have not been positively selected in the three continental human populations. This finding suggests that, contrary to results of previous studies, different allele frequencies among populations in genes such as TAS2R38 and TAS2R16 are not due to positive selection but to genetic drift. CYP1 and CYP2 genes, also previously considered to be under positive selection, did not show signatures of selective sweeps. However, three genes belonging to the CYP450 system have been identified by the Hierarchical Boosting as positively selected: CYP3A4 and CYP3A43 in CEU, and CYP27A1 in CHB.

Conclusions

No main adaptive differences are found in known taste receptor genes among the three continental human populations studied. However, there are important genetic adaptations in the cytochrome P450 system related to the Out of Africa expansion of modern humans. We confirmed that CYP3A4 and CYP3A43 are under selection in CEU, and we report for the first time CYP27A1 to be under positive selection in CHB.

Electronic supplementary material

The online version of this article (10.1186/s12862-019-1366-7) contains supplementary material, which is available to authorized users.

Interaction of herbal products with prescribed medications: A systematic review and meta-analysis

Although several studies on pharmacokinetic and/or pharmacodynamic herb-drug interactions (HDI) have been conducted in healthy volunteers, there is large uncertainty on the validity of these studies. A qualitative review and a meta-analysis were performed to establish the clinical evidence of these interaction studies. Out of 4026 screened abstracts, 32 studies were included into the qualitative analysis. The meta-analysis was performed on eleven additional studies. St. John's wort (SJW) significantly decreased the AUC (p < 0.0001) and clearance (p = 0.007) of midazolam. Further subgroup analysis identified age to affect C_max of midazolam (p < 0.01) in the presence of SJW. Echinacea purpurea (EP) significantly increased the clearance of midazolam (p = 0.01). Evidence of publication bias (p > 0.001) was shown on the effect of the herbal products o half-life of midazolam. Green tea (GT) showed significant 85% decrease in plasma concentration of nadolol. The study findings suggest that GT, SJW and EP perpetuate significant interactions with prescribed medications via CYP3A4 or OATP1A2. Our studies show that meta-analyses are important in the area of natural products to provide necessary information on their use in overall medication plans in order to avoid unintended interactions.

Clinically relevant drug interactions with multikinase inhibitors: a review

Multikinase inhibitors (MKIs), including the tyrosine kinase inhibitors (TKIs), have rapidly become an established factor in daily (hemato)-oncology practice. Although the oral route of administration offers improved flexibility and convenience for the patient, challenges arise in the use of MKIs. As MKIs are prescribed extensively, patients are at increased risk for (severe) drug–drug interactions (DDIs). As a result of these DDIs, plasma pharmacokinetics of MKIs may vary significantly, thereby leading to high interpatient variability and subsequent risk for increased toxicity or a diminished therapeutic outcome. Most clinically relevant DDIs with MKIs concern altered absorption and metabolism. The absorption of MKIs may be decreased by concomitant use of gastric acid-suppressive agents (e.g. proton pump inhibitors) as many kinase inhibitors show pH-dependent solubility. In addition, DDIs concerning drug (uptake and efflux) transporters may be of significant clinical relevance during MKI therapy. Furthermore, since many MKIs are substrates for cytochrome P450 isoenzymes (CYPs), induction or inhibition with strong CYP inhibitors or inducers may lead to significant alterations in MKI exposure. In conclusion, DDIs are of major concern during MKI therapy and need to be monitored closely in clinical practice. Based on the current knowledge and available literature, practical recommendations for management of these DDIs in clinical practice are presented in this review.

Chronic myeloid leukaemia and tyrosine kinase inhibitor therapy: assessment and management of cardiovascular risk factors

Several BCR-ABL1 tyrosine kinase inhibitors (TKIs) are approved for the first-line treatment of chronic phase chronic myeloid leukaemia (CML). Disease control is achieved in the vast majority of patients and disease-specific survival is excellent. Consequently, there is now emphasis on managing comorbidities and minimising treatment-related toxicity. Second-generation TKIs have cardiovascular risks that are greater than with imatinib treatment, but these risks must be balanced against the superior CML responses encountered with more potent TKIs. Cardiovascular risk should be assessed at baseline using a locally validated model based on the Framingham risk equation. Clinicians involved in the care of CML patients should be aware of the vascular complications of TKIs and manage cardiovascular risk factors early to mitigate treatment-related risks. Reversible risk factors, such as dyslipidaemia, smoking, diabetes and hypertension, should be addressed. We summarise the available data on cardiovascular complications in CML patients treated with TKIs. Using the latest evidence and collective expert opinion, we provide practical advice for clinicians to assess, stratify and manage cardiovascular risk in people with CML receiving TKI therapy.

Efficacy and Safety of Edoxaban in Patients With Active Malignancy and Atrial Fibrillation: Analysis of the ENGAGE AF - TIMI 48 Trial

Background Anticoagulation in patients with malignancy and atrial fibrillation is challenging because of enhanced risks for thrombosis and bleeding and the frequent need for invasive procedures. Data on direct oral antagonists in such patients are sparse. Methods and Results The ENGAGE AF - TIMI 48 (Effective Anticoagulation With Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis in Myocardial Infarction Study 48) trial randomized 21 105 patients with atrial fibrillation to edoxaban or warfarin. Patients with malignancy, defined as a postrandomization new diagnosis or recurrence of remote cancer, were followed up over a median of 2.8 years. Adjusted Cox proportional hazard models were used to evaluate the safety and efficacy of edoxaban versus warfarin. Over a median of 495 days (interquartile range, 230-771 days), 1153 patients (5.5%) were diagnosed with new or recurrent malignancy, most commonly involving the gastrointestinal tract (20.6%), prostate (13.6%), and lung (11.1%). Malignancy was associated with increased risk of death (adjusted hazard ratio [HR], 3.12; 95% confidence interval [CI], 2.78-3.50) and major bleeding (adjusted HR, 2.45; 95% CI, 2.07-2.89), but not stroke/systemic embolism (adjusted HR, 1.08; 95% CI, 0.83-1.42). Relative outcomes with higher-dose edoxaban versus warfarin were consistent regardless of malignancy status for stroke/systemic embolism ( HR , 0.60 [95% CI, 0.31-1.15] for malignancy versus HR , 0.89 [95% CI, 0.76-1.05] for no malignancy; interaction P=0.25) and major bleeding ( HR , 0.98 [95% CI, 0.69-1.40] for malignancy versus HR , 0.79 [95% CI, 0.69-1.05] for no malignancy; interaction P=0.31). There was, however, a significant treatment interaction for the composite ischemic end point (ischemic stroke/systemic embolism/myocardial infarction), with greater efficacy of higher-dose edoxaban versus warfarin in patients with malignancy ( HR , 0.54; 95% CI, 0.31-0.93) compared with no malignancy ( HR , 1.02; 95% CI, 0.88-1.18; interaction P=0.026). Conclusions In patients with atrial fibrillation who develop malignancy, the efficacy and safety profile of edoxaban relative to warfarin is preserved, and it may represent a more practical alternative.

Role of Cytochrome P450 Enzymes in the Metabolic Activation of Tyrosine Kinase Inhibitors

Tyrosine kinase inhibitors are a rapidly expanding class of molecular targeted therapies for the treatment of various types of cancer and other diseases. An increasing number of clinically important small molecule tyrosine kinase inhibitors have been shown to undergo cytochrome P450-mediated bioactivation to form chemically reactive, potentially toxic products. Metabolic activation of tyrosine kinase inhibitors is proposed to contribute to the development of serious adverse reactions, including idiosyncratic hepatotoxicity. This article will review recent findings and ongoing studies to elucidate the link between drug metabolism and tyrosine kinase inhibitor-associated hepatotoxicity.

Challenges in ALK inhibition of ALK-positive non-small-cell lung cancer: from ALK positivity detection to treatment strategies after relapse

ALK positivity, despite representing only in a small proportion of patients with non-small-cell lung cancer, is worth researching at diagnosis given the possibility to treat these patients with some targeted ALK inhibitors, which are more potent than chemotherapy. Thanks to understanding the resistance mechanisms, newer and more selective inhibitors are now available in clinical practice. Hence, this disease represents, after EGFR inhibition, a largely effective precision medicine approach. However, there are still some clinical situations in which the targeted drug seems to be ineffective. This review discusses some uncertainty about such a 'precision medicine application', focusing on some weaknesses and giving perspectives and suggestions to improve the management of this specific population.

Metabolic profiling of the anti-tumor drug regorafenib in mice

Regorafenib is a novel tyrosine kinase inhibitor, which has been approved by the United States Food and Drug Administration for the treatment of various tumors. The purpose of the present study was to describe the metabolic map of regorafenib, and investigate its effect on liver function. Mass spectrometry-based metabolomics approach integrated with multiple mass defect filter was used to determine the metabolites of regorafenib in vitro incubation mixtures (human liver microsomes and mouse liver microsomes), serum, urine and feces samples from mice treated with 80 mg/kg regorafenib. Eleven metabolites including four novel metabolites were identified in the present investigation. As halogen substituted drug, reductive defluorination and oxidative dechlorination metabolites of regorafenib were firstly report in present study. By screening using recombinant cytochrome P450 s (CYPs), CYP3A4 was found to be the principal isoforms involved in regorafenib metabolism. The predication with a molecular docking model confirmed that regorafenib had potential to interact with the active sites of CYP3A4, CYP3A5 and CYP2D6. Serum chemistry analysis revealed no evidence of hepatic damage from regorafenib exposure. This study provided a global view of regorafenib metabolism and its potential side-effects.

Analysis of Clinical Drug-Drug Interaction Data To Predict Magnitudes of Uncharacterized Interactions between Antiretroviral Drugs and Comedications

Despite their high potential for drug-drug interactions (DDI), clinical DDI studies of antiretroviral drugs (ARVs) are often lacking, because the full range of potential interactions cannot feasibly or pragmatically be studied, with some high-risk DDI studies also being ethically difficult to undertake. Thus, a robust method to screen and to predict the likelihood of DDIs is required. We developed a method to predict DDIs based on two parameters: the degree of metabolism by specific enzymes, such as CYP3A, and the strength of an inhibitor or inducer. These parameters were derived from existing studies utilizing paradigm substrates, inducers, and inhibitors of CYP3A to assess the predictive performance of this method by verifying predicted magnitudes of changes in drug exposure against clinical DDI studies involving ARVs. The derived parameters were consistent with the FDA classification of sensitive CYP3A substrates and the strength of CYP3A inhibitors and inducers. Characterized DDI magnitudes (n = 68) between ARVs and comedications were successfully quantified, meaning 53%, 85%, and 98% of the predictions were within 1.25-fold (0.80 to 1.25), 1.5-fold (0.66 to 1.48), and 2-fold (0.66 to 1.94) of the observed clinical data. In addition, the method identifies CYP3A substrates likely to be highly or, conversely, minimally impacted by CYP3A inhibitors or inducers, thus categorizing the magnitude of DDIs. The developed effective and robust method has the potential to support a more rational identification of dose adjustment to overcome DDIs, being particularly relevant in an HIV setting, given the treatment's complexity, high DDI risk, and limited guidance on the management of DDIs.

Combination therapy for metastatic melanoma: a pharmacist's role, drug interactions & complementary alternative therapies

The incidence of metastatic melanoma has been increasing dramatically over the last decades. Yet, there have been many new innovative therapies, such as targeted therapies and checkpoint inhibitors, which have made progress in survival for these patients. The oncology pharmacist is part of the healthcare team and can help in optimizing these newer therapies. There will be discussion about combination therapies, the oncology pharmacist's role, and issues at the core of his interest, such as drug interactions and complementary and alternative therapies.

The cytochrome P450 isoenzyme and some new opportunities for the prediction of negative drug interaction in vivo

Cytochrome (CYP) 450 isoenzymes are the basic enzymes involved in Phase I biotransformation. The most important role in biotransformation belongs to CYP3A4, CYP2D6, CYP2C9, CYP2C19 and CYP1A2. Inhibition and induction of CYP isoenzymes caused by drugs are important and clinically relevant pharmacokinetic mechanisms of drug interaction. Investigation of the activity of CYP isoenzymes by using phenotyping methods (such as the determination of the concentration of specific substrates and metabolites in biological fluids) during drug administration provides the prediction of negative side effects caused by drug interaction. In clinical practice, the process of phenotyping of CYP isoenzymes and some endogenous substrates in the ratio of cortisol to 6β-hydroxycortisol in urine for the evaluation of CYP3A4 activity has been deemed to be a quite promising, safe and minimally invasive method for patients nowadays.

Development of a method to determine axitinib, lapatinib and afatinib in plasma by micellar liquid chromatography and validation by the European Medicines Agency guidelines

A method based on micellar liquid chromatography to quantify the tyrosine kinase inhibitors axitinib, lapatinib and afatinib in plasma is reported. The sample pretreatment was a simple 1/5-dilution in a pure micellar solution, filtration and direct injection, without requiring extraction or purification steps. The three drugs were resolved from the matrix in 17min, using an aqueous solution of 0.07M sodium dodecyl sulfate - 6.0% 1-pentanol, buffered at pH7 with 0.01M phosphate salt as mobile phase, running under isocratic mode at 1mL/min through a C18 column. The detection was performed by absorbance at 260nm. An accurate mathematical relationship was established between the retention factor of each drug and the surfactant/organic solvent concentration in the mobile phase, achieved with a limited number of experiments, in order to optimize these factors. A binding behavior of the analytes face to the micelles was found out. The method was successfully validated by the guidelines of the European Medicines Agency in terms of: selectivity, linearity (r²>0.9995), calibration range (0.5 to 10mg/L), limit of detection (0.2mg/L), carry-over effect, accuracy (-8.1 to +6.9%), precision (<13.8%), dilution integrity, matrix effect, stability and robustness. The procedure was found reliable, practical, economic, accessible, short-time, easy-to-handle, inexpensive, environmental-friendly, safe, useful for the analysis of many samples per day. Finally, the method was applied to the analysis of incurred, using quality control samples in the same analytical run, with adequate results. Therefore, it can be implementable for routine analysis in clinical laboratories.

Herbal Bioenhancers in Veterinary Phytomedicine

Herbal bioenhancers are active phytomolecules that increase the bioavailability, bioefficacy and biological activity of various drugs when coadministered at low concentrations. These valuable compounds reduce the dose, increase the treatment rate, decrease the treatment duration, drug resistance or related adverse reactions which have economical implications in livestock and pet medicine. Eventhough the concept of herbal bioenhancers are known for years through Ayurvedic medicine, the underlying mechanisms remains unclear. The main mechanisms involved are related to drug absorption (effect on solubility, drug efflux and transport proteins, increased permeability in gastrointestinal system) and drug metabolism (inhibition/induction of drug metabolysing enzymes, thermogenic effect). Due to species specific differences in these mechanisms, corresponding data on human and laboratory animal could not be attributed. As multidrug resistance is a major treat to both human and animal health, within "One Health" concept, efficient therapeutical strategies are encouraged by authorities, where focus on herbal supplements as a vast unexploited field remains to be researched within "Bioenhancement Concept." This review brings insight to mechanims involved in bioenhancing effect, examples of herbal extracts and phytoactive compounds and their potential in the veterinary medicine including different classes of drugs such as antibiotics, anticancerous, antiviral, and antituberculosis.

Evaluation of the pharmacokinetic drug interaction potential of tivantinib (ARQ 197) using cocktail probes in patients with advanced solid tumours

AIMS

This phase 1, open-label, crossover study sought to evaluate drug-drug interactions between tivantinib and cytochrome P450 (CYP) substrates and tivantinib and P-glycoprotein.

METHODS

The effect of tivantinib doses on the pharmacokinetics of the probe drugs for CYP1A2 (caffeine), CYP2C9 (S-warfarin), CYP2C19 (omeprazole), and CYP3A4 (midazolam), and for P-glycoprotein (digoxin) was investigated in 28 patients with advanced cancer using a cocktail probe approach. Patients received single doses of probe drugs alone and, after 5 days of treatment, with tivantinib 360 mg twice daily.

RESULTS

The ratios of geometric least squares mean (90% confidence interval) for the area under the concentration-time curve from time zero to the last quantifiable concentration in the presence/absence of tivantinib were 0.97 (0.89-1.05) for caffeine, 0.88 (0.76-1.02) for S-warfarin, 0.89 (0.60-1.31) for omeprazole, 0.83 (0.67-1.02) for midazolam, and 0.69 (0.51-0.94) for digoxin. Similar effects were observed for maximum plasma concentrations; the ratio for digoxin in the presence/absence of tivantinib was 0.75 (0.60-0.95).

CONCLUSIONS

The data suggest that tivantinib 360 mg twice daily has either a minimal or no effect on the pharmacokinetics of probe drugs for CYP1A2, CYP2C9, CYP2C19 and CYP3A4 substrates, and decreases the systemic exposure of P-glycoprotein substrates when administered with tivantinib.

Individualized dosing with axitinib: rationale and practical guidance

Axitinib is a potent, selective, vascular endothelial growth factor receptor inhibitor with demonstrated efficacy as second-line treatment for metastatic renal cell carcinoma. Analyses of axitinib drug exposures have demonstrated high interpatient variability in patients receiving the 5 mg twice-daily (b.i.d.) starting dose. Clinical criteria can be used to assess whether individual patients may benefit further from dose modifications, based on their safety and tolerability data. This review provides practical guidance on the 'flexible dosing' method, to help physicians identify who would benefit from dose escalations, dose reductions or continuation with manageable toxicity at the 5 mg b.i.d. dose. This flexible approach allows patients to achieve the best possible outcomes without compromising safety.

Structure-Based Kinase Profiling To Understand the Polypharmacological Behavior of Therapeutic Molecules

Several drugs elicit their therapeutic efficacy by modulating multiple cellular targets and possess varied polypharmacological actions. The identification of the molecular targets of a potent bioactive molecule is essential in determining its overall polypharmacological profile. Experimental procedures are expensive and time-consuming. Therefore, computational approaches are actively implemented in rational drug discovery. Here, we demonstrate a computational pipeline, based on reverse virtual screening technique using several consensus scoring strategies, and perform structure-based kinase profiling of 12 FDA-approved drugs. This target prediction showed an overall good performance, with an average AU-ROC greater than 0.85 for most drugs, and identified the true targets even at the top 2% cutoff. In contrast, 10 non-kinase binder drugs exhibited lower binding efficiency and appeared in the bottom of ranking list. Subsequently, we validated this pipeline on a potent therapeutic molecule, mahanine, whose polypharmacological profile related to targeting kinases is unknown. Our target-prediction method identified different kinases. Furthermore, we have experimentally validated that mahanine is able to modulate multiple kinases that are involved in cross-talk with different signaling molecules, which thereby exhibits its polypharmacological action. More importantly, in vitro kinase assay exhibited the inhibitory effect of mahanine on two such predicted kinases' (mTOR and VEGFR2) activity, with IC₅₀ values being ∼12 and ∼22 μM, respectively. Next, we generated a comprehensive drug-protein interaction fingerprint that explained the basis of their target selectivity. We observed that it is controlled by variations in kinase conformations followed by significant differences in crucial hydrogen-bond and van der Waals interactions. Such structure-based kinase profiling could provide useful information in revealing the unknown targets of therapeutic molecules from their polypharmacological behavior and would assist in drug discovery.

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.

Mechanisms of toxicity associated with six tyrosine kinase inhibitors in human hepatocyte cell lines

Tyrosine kinase inhibitors have revolutionized the treatment of certain cancers. They are usually well tolerated, but can cause adverse reactions including liver injury. Currently, mechanisms of hepatotoxicity associated with tyrosine kinase inhibitors are only partially clarified. We therefore aimed at investigating the toxicity of regorafenib, sorafenib, ponatinib, crizotinib, dasatinib and pazopanib on HepG2 and partially on HepaRG cells. Regorafenib and sorafenib strongly inhibited oxidative metabolism (measured by the Seahorse-XF24 analyzer) and glycolysis, decreased the mitochondrial membrane potential and induced apoptosis and/or necrosis of HepG2 cells at concentrations similar to steady-state plasma concentrations in humans. In HepaRG cells, pretreatment with rifampicin decreased membrane toxicity (measured as adenylate kinase release) and dissipation of adenosine triphosphate stores, indicating that toxicity was associated mainly with the parent drugs. Ponatinib strongly impaired oxidative metabolism but only weakly glycolysis, and induced apoptosis of HepG2 cells at concentrations higher than steady-state plasma concentrations in humans. Crizotinib and dasatinib did not significantly affect mitochondrial functions and inhibited glycolysis only weakly, but induced apoptosis of HepG2 cells. Pazopanib was associated with a weak increase in mitochondrial reactive oxygen species accumulation and inhibition of glycolysis without being cytotoxic. In conclusion, regorafenib and sorafenib are strong mitochondrial toxicants and inhibitors of glycolysis at clinically relevant concentrations. Ponatinib affects mitochondria and glycolysis at higher concentrations than reached in plasma (but possibly in liver), whereas crizotinib, dasatinib and pazopanib showed no relevant toxicity. Mitochondrial toxicity and inhibition of glycolysis most likely explain hepatotoxicity associated with regorafenib, sorafenib and possibly pazopanib, but not for the other compounds investigated.

Pharmacovigilance during ibrutinib therapy for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) in routine clinical practice

Due to Cytochrome P450 3A (CYP3A) metabolism, clinical trials of ibrutinib-treated chronic lymphocytic leukemia (CLL) patients prohibited concurrent medications metabolized by CYP3A. We evaluated concomitant medication use in 118 ibrutinib-treated CLL patients outside the context of clinical trials. Seventy-five (64%) patients were on medications that could increase ibrutinib toxicity and 4 (3%) were on drugs that could decrease ibrutinib efficacy. Nineteen (16%) patients were on concomitant CYP3A inhibitors (11 moderate, 8 strong), and 4 (3%) were on CYP3A inducers (two patients were on both CYP3A inhibitors and inducers). Although the ibrutinib starting dose was changed in 18 patients on CYP3A interacting medications, no difference in 18-month progression-free survival or rate of ibrutinib discontinuation was observed in patients who were not. In routine clinical practice, 2 of 3 CLL patients commencing ibrutinib are on a concomitant medication with potential to influence ibrutinib metabolism. Formal medication review by a pharmacist should be considered in all patients initiating ibrutinib.

Evaluation of the impact of 16-dehydropregnenolone on the activity and expression of rat hepatic cytochrome P450 enzymes

16-dehydropregnenolone (DHP) is a promising novel antihyperlipidemic agent developed and patented by Central Drug Research Institute (CDRI), India. The purpose of the present study was to investigate whether DHP influences the activities and mRNA expression of hepatic drug-metabolizing cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C11, CYP2D2, CYP2E1 and CYP3A1) in Sprague-Dawley (SD) rats. A cocktail suspension of CYP probe substrates which contained caffeine (CYP1A2), tolbutamide (CYP2C11), dextromethorphan (CYP2D2), chlorzoxazone (CYP2E1) and dapsone (CYP3A1) was administered orally on eighth- or fifteenth-day to rats pre-treated with DHP intragastrically at a dose of 36 and 72mg/kg for one week and two weeks. The concentrations of probe drugs in plasma were estimated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Alongside, the effect of DHP on CYPs activity and mRNA expression levels were assayed in isolated rat liver microsomes and by real-time reverse transcription-polymerase chain reaction (RT-PCR), respectively. DHP had significant inducing effects on CYP1A2, 2C11, 2D2 and 2E1 with no effect on CYP3A1 in dose- and time-dependent manner, as revealed from the pharmacokinetic profiles of the probe drugs in rats. In-vitro microsomal activities and mRNA expression results were in good agreement with the in-vivo pharmacokinetic results. Collectively, the results unveiled that DHP is an inducer of rat hepatic CYP enzymes. Hence, intense attention should be paid when DHP is co-administered with drugs metabolized by CYP1A2, 2C11, 2D2 and 2E1, which might result in drug-drug interactions and therapeutic failure.