Williams Oncology Study Fin


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Talk give at the Northwest Oncology meeting 2012

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  • Different chemical classesAnd different therapeutic areas
  • Major consequence of bioactivation is in fact bioinactivation
  • Mjajorr consequence of bioactivation is in fact bioinactivation
  • Most common consequence of bioactivation is in fact bioinactivation
  • The physiological role of the liver is hepatic clearance.Interference with this process, can itself be a cause of DILIDawson et al quantified the inhibition of BSEP ABCB 11 by 85 pharmaceuticals using taurochalate uptake in inverted plasma membrane vesicles from Sf 21 cells which express these proteins.Overall they found that inhibition of both human BSEP and the rat ortholog (rBsep) correlates with the propensitiyOf numerous pharmaceuticals to cause to cause cholestatic DILI
  • What are we trying to predict?
  • We believe that neoadjuvant chemotherapy is beneficial for patients undergoing resection of colorectal liver metastases. These data are from the EORTC study, where 364 patients with resectable colorectal hepatic metastases were randomized to six cycles of neoadjuvant FOLFOX, followed by surgery and six further cycles of chemotherapy, or surgery alone. Those who received perioperative chemotherapy and were resected had a 9.2% improvement in 3-year disease-free survival.
  • However, there is growing recognition that preoperative systemic chemotherapy can adversely affect normal hepatic parenchyma. Patients who receive systemic oxaliplatin are more likely to develop sinusoidal obstructive syndrome, whilst those treated with Irinotecan are more likely to developed steatosis and steatohepatitis. Sinusoidal obstructive syndrome is associated with increased intraoperative bleeding, but no increase in morbidity and mortality. Steatohepatitis is associated with increased post-operative morbidty, and Vauthey at el demonstrated a strong correlation between steatohepatitis and 90-day mortality after resection.
  • Williams Oncology Study Fin

    1. 1. Mechanisms ofunpredictable toxicities Dominic Williams MRC Centre for Drug Safety Science The University of Liverpool dom@liv.ac.uk
    2. 2. OverviewMRC CDSS strategy for adverse drug reaction (ADR) researchClassification of ADRsRole of drug metabolismFocus on Drug-Induced Liver Injury (DILI) Mechanisms Polymorphisms in drug metabolising enzymesPharmacogenetics in the treatment of cancerNeoadjuvant chemotherapy & DILI
    3. 3. Centre Strategy for Investigating ADRs DRUG Define structural CharacterizeInvestigation basis of ADR Investigation of the liability of the chemical “Closing the loop” patient on adverse drug reactions Identify Characterize causal patient biochemical phenotype/ variable genotype
    4. 4. Integrated Mechanistic Drug Safety: Patient SAR Drug SMR Class STR Animal Chemistry Clinical Research Man Bioanalysis Mechanism OutcomesProblem Question Biomarkers In vitro Clinical Samples
    5. 5. Integrated Mechanistic Drug Safety: Chemical SAR SMR STR In vitro Drug / Chemical Man Chemical Biological BioanalysisCompound Studies Validation Validation Animal Clinical Validation & Application
    6. 6. Lessons for the futureInform mechanism and pathogenesisInform the Medicinal ChemistInform the ClinicianInform the RegulatorInform the Public – what is feasibleDevelop biomarkers for integratedpatient, in vitro & animal studies
    7. 7. Classification of Adverse Drug ReactionsON TARGET • Predictable from the known primary or secondary pharmacology of the drug • Exaggeration of the pharmacological effect of the drug • Clear dose-dependent relationshipOFF TARGET • These are not predictable from a knowledge of the basic pharmacology of the drug • Exhibit marked inter-individual susceptibility (idiosyncratic) • Complex dose dependence
    8. 8. Drug Metabolism: Pharmacology Cellular DRUG RESPONSE accumulation Concentration inPhase I/II Plasma Drug Stable Dispositionmetabolites Metabolism Absorption Excretion Drug plasma level Excretion Pharmacological exposure
    9. 9. Drug Metabolism: Toxicology Cellular DRUG RESPONSE accumulation Concentrations in organsPhase I/II Drug Stable Dispositionmetabolites Metabolism Absorption Excretion Drug & metabolites Excretion Pharmacological & Toxicological exposure
    10. 10. Drugs withdrawn from major markets due to hepatotoxicity Drug: Therapeutic area: - Alpidem* Anxiolytic Aspirin (children) NSAID - - Bendazac* NSAID Benoxaprofen NSAID - O NH 2 - Bromfenac* NSAID HO OH Chlormezanone* Anxiolytic - NH - Dilavelol* Anti-hypertensive Ebrotidine* H2 receptor antagonist - - Fipexide* Stimulant Nefazodone* Anti-depressant - - Nimesulide NSAID Nomifensine Anti-depressant - - Oxyphenisatin Laxative Pemoline* ADHD - - Perhexilene Anti-anginal Temafloxacin* Anti-infective - - Tolcapone* Anti-parkinson’s Tolrestat* Anti-diabetic - - Troglitazone* Anti-diabetic Trovafloxacin* Antibiotic - Ximelagatran- Anti-coagulant - Zimeldine Anti-depressant * Need et al., Nat Genetics 2005
    11. 11. Drug Disposition: Pharmacological & Toxicological Cellular DRUG accumulation ToxicityPhase I/II/III bioactivation Chemically Stable reactivemetabolites metabolites bioinactivation Excretion
    12. 12. Consequences of bioactivation Cellular DRUG accumulation ToxicityPhase I/II/III bioactivation Inhibition Chemically • heme complex Of reactive • protein alkylation P450s metabolites bioinactivation Excretion
    13. 13. Consequences of bioactivation Cellular DRUG accumulation Toxicity CarcinogenicityPhase I/II/III bioactivation Chemical Stress Modification of: Chemically Necrosis Stable reactive • nucleic acidmetabolites metabolites • enzyme • transporter Apoptosis bioinactivation • signalling protein • receptor • random autologous Excretion protein Hypersensitivity
    14. 14. Consequences of bioactivation: Toxicophores (structural alerts) Cellular DRUG accumulation Toxicity ?? furan thiophene aliphatic aminePhase I/II/III bioactivation aromatic amine epoxide Chemically quinone Stable quinoneimine reactivemetabolites carbocation metabolites acyl halide bioinactivation hydroxylamine allylic alcohol acyl glucuronide Excretion PHARMACOLOGICAL ADVERSE EFFECT EFFECT CHEMICAL STRUCTURE
    15. 15. Hepatotoxic drugs in man: Withdrawn or with warning labelDrugs with black warnings for hepatotoxicity* Drugs withdrawn for hepatotoxicitydrug dose (mg/day) reactive products drug date dose reactiveacitretin 25-50 no (mg/day) productsbosentan 125-250 no cincopher 1930 300 nodacarbazine 140-315 yes iproniazid 1959 25-150 yesdantrolene 300-400 yes pipamazinc 1969 15 nofelbamate 1200 yes fenclozic acid 1970 300 yesflutamide 750 yes oxyphenisatin 1973 50 no 2011; 10: 1-15gemtuzumab 9 mg.m-3 yes (?) nialamide 1974 200 yesisoniazid 300 yes tienilic acid 1980 250-500 yesketoconazole 200 yes benoxaprofen 1982 300-600 yesnaltrexone 50 no nomifensine 1986 125 yesnevirapine 200 yes chlomezanone 1996 600 notolcapone 300 yes bromfenac 1998 25-50 yestrovafloxacin 100-500 no troglitazone 2000 400 yesvalproic acid 1000-2400 Yes (10/14 = 71%) nefazodone 2004 200 yes*Definition: a black box warning is the strongest type of warning that the pemoline 2005 38-110 noFDA can require for a drug and is generally reserved for warningprescribers about adverse drug reactions that can cause serious injury ordeath. An issue here is the benefit/risk ratio.
    16. 16. Focus on Drug-Induced Liver Injury SM EC CLEARANCE phospholipidosis DRUG bioaccumulation mitochondria microvesicular steatosis METABOLITE organelle impairment lysosome hepatocyte apoptosisREACTIVE METABOLITE hepatocyte necrosis inhibition of biliary efflux CLEARANCE hypersensitivity Intrahepatic cholestasis immunoallergic toxicity
    17. 17. DILI – a consequence of multiple steps Drug Patient-specificfactors Drug-specific factors 1. 2. 3. Biological response in 4. Biological response in Chemical Insult in liverDrug absorption & disposition target cell tissue e.g. reactive metabolite-e.g. hepatic uptake e.g. cell toxicity, stress e.g. cytokine release, mediated response immune cell response Screening opportunity Outcome: pre-clinical species vs man Amplification vs Innate & adaptive Protection immunity e.g. stress response Tolerance & adaptation Toxicity
    18. 18. Clinicopathological presentation of DILI CLEARANCE Acute fatty liver with lactic acidosis Acute hepatic necrosis DRUG Acute liver failure Acute viral hepatitis-like liver injury Autoimmune-like hepatitis DRUG Bland cholestasis + Cholestatic hepatitis METABOLITE Cirrhosis Immuno-allergic hepatitis Nodular regeneration Nonalcoholic fatty liver Sinusoidal obstruction syndrome Vanishing bile duct syndrome Multi-cellular and multifunctional organ Multiple and variable forms of disease Multi step pathologies Tujios and Fontana Nature 2011
    19. 19. Hepatotoxin Accumulation Mit DNA Energy Depletion Fialuridine OXPHOS ROS Generation Fatty acid synthesis ApoptosisHepatocellularTargets Toxic Consequences hENT1 Steatosis Toxicity Mechanisms Inhibits DNA polymerase-γ of Reactive Independent Oxidative Stress Transporters Metabolites Protein Oxidation Decreases MtDNA Perhexiline Apoptosis Fialuridine Necrosis Disrupts electron transportAplovirac chain Tacrine Mitochondria Steatosis ROS generation Valproic Acid Amiodarone Troglitazone Mitochondrial Dysfunction/Cell Death Accumulation Ritonavir • Physicochemical Rifampin • Biochemical NRTIs eg Stavudine • Transport
    20. 20. Hepatotoxin Accumulation Mit DNA Energy Depletion Fialuridine OXPHOS ROS Generation Fatty acid synthesis ApoptosisHepatocellularTargets Toxic Consequences Steatosis Toxicity Mechanisms Independent of Reactive Oxidative Stress Transporters Metabolites Protein Oxidation Perhexiline Apoptosis Fialuridine Necrosis Aplovirac Tacrine Mitochondria Steatosis Valproic Acid Amiodarone Troglitazone Accumulation Ritonavir • Physicochemical Rifampin • Biochemical NRTIs eg Stavudine • Transport McKenzie et al, 1995 Lai et al, 2004
    21. 21. Mechanisms of Drug Induced Liver Injury Hepatic Injury Biological stratification Drug • accumulation • Plasma / liver level • bioactivation • GSH/mercapturate • covalent binding • Protein binding • chemical stress • chemical stress DRUG METABOLITE • mitochondrial dysfunction • glutamate dehydrogenaseREACTIVE METABOLITE • apoptosis • cytochrome C • hepatocyte hypertrophy • hepatocyte hyperplasia • ALT, AST, SDH, LDH, GST • hepatocyte integrity • ALP, GT, 5’nucleotidase • hepatobiliary integrity Biology • Bilirubin, bile acids, • innate immune activation • hepatic function • prothrombin, metabolism / • fibrosis secretion
    22. 22. Variation in Drug Metabolism - Toxicity Cellular DRUG accumulation Toxicity VariationH NPhase I/II/III In drug metabolism Stable Perhexiline & metabolites Genetic Variation In genetics Cytochrome P450 enzyme induction enzyme inhibition Excretion disease Shah et al 1982; Davies et al 2007
    23. 23. Perhexiline Maleate and CYP2D6 HIndications - prevention of angina pectoris N - prevention of ventricular systolesToxicity - peripheral neuropathy - hepatotoxicity HO H NPharmacokinetics: T1/2 Metabolic ratio (%D/%M)- ADR patients 2-6 0.3 ± 0.4+ ADR patients 9-22 2.82 ± 0.4 - related to CYP2D6 phenotype (Singlas et al, 1978; Shah et al, 1982; Cooper et al, 1984)
    24. 24. Lipidosis Induced by Amphiphilic Cationic Drugs N H PHOSPHOLIPIDS PHOSPHOLIPIDS N N N H H H Extracellular Cytosol pH 7.4 pH 7.2 Lysosome pH 4.5
    25. 25. Prediction of Variation in Drug Metabolism • Human liver banks • Expression systems • Cell lines • In silico techniques / models • Transgenic animals • Volunteer & Patient studies • Genotype • Phenotype Transfer of knowledge Development of to clinical practice pre-clinical screens
    26. 26. Drug Safety Science and DILI CLEARANCE 20 / safety pharmacology targets 1st effects 2nd effects 3rd effects Ca2+ Occurrence,DRUG Frequency = f1 + f2DRUG Chemistry Biology of & Severity of + DNA of drug individual Drug Hepatotoxicity METABOLITE phospholipid specificTARGET proteins BIOMARKERS PHARMACOLOGICAL ADVERSE EFFECT EFFECT Dose CHEMICAL STRUCTURE f (chemistry) f (biology) SPECIES and INDIVIDUAL VARIATION
    27. 27. Drug Safety Science and DILIOccurrence, Frequency & Severity ofDrug Hepatotoxicity = f1 Chemistry of drug + f2 Biology of individual N H Amphiphilic 2D6 genotype / Cation phenotype Rationale for Safe clinical use
    28. 28. Genetic Polymorphisms known to affectresponse to anti-cancer drugs Relling & Dervieux, 2001; Nature Reviews Cancer
    29. 29. Pharmacogenetics in the Treatment of Cancer thiopurine methyl transferase 6-mercaptopurine TPMT inactive metabolites Azathioprine Active Incorporation into DNA thioguanine Anti-leukemic effect nucleotides Myelosuppression 1 in 300 have TPMT deficiency Several polymorphisms including G238C, G460A and A719G TPMT deficiency predicts severe neutropenia following treatment with 6-mercaptopurine or azathioprine Krynetski & Evans, 1998
    30. 30. Thiopurine Methyl Transferase (TPMT)and Treatment of Childhood Leukaemia Myelotoxicity ↑ Risk of 2o cancer Narrow therapeutic index Therapy ↓ toxicity 1:300 have TPMT deficiency Risk of relapse 0.3% mut/mut 10% wt/mut 90% wt/wt Associated with severe Dose adjustment haemopoietic toxicity 6-Mercaptopurine dosage 500 (mg/m2/week) REDUCTION OF DOSE TO 10% CAN LEAD TO SUCCESSFUL TREATMENT 25 0 WITHOUT TOXICITY 25 m /m w t/m w t/w t Krynetski & Evans, 1998
    31. 31. Neoadjuvant chemotherapy improvesprogression free survival Neoadjuvant chemotherapy in colorectal liver metastases: 5-fluorouracil Leucovorin Oxaliplatin } FOLFOX 5-fluorouracil Leucovorin Irinotecan } FOLFIRI EORT study: 9.2% improvement 3 year disease-free survival (FOLFOX) Pre-operative chemotherapy can cause problems Nordlinger, Lancet 2008
    32. 32. Irinotecan Metabolism & ToxicityIrinotecan (Campostar®) is a topoisomerase-I inhibitor pro-drug widely used fortreatment of metastatic and recurrent colorectal cancerThe most common dose-limiting adverse effects of irinotecan are neutropenia &diarrhoeaUGT normally conjugates to & increases hydrophilicity of bilirubin, drugs &xenobioticsVariations in uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene mayhelp predict which patients develop adverse effectsFrequency of the inactive allele varies: African (43%), European (39%) Asian(16%)
    33. 33. Irinotecan Metabolism N CH2CH3 N O OIrinotecan N Cyp 3A4/5 Oxidised O N Irinotecan O Carboxyl H3CH2C OH O esterase CH2CH3 HO O SN38 N (active) N Anti-tumour O activity H3CH2C OH O UGT 1A1 / 7 / 9 CH2CH3 GLUCURONIDE O O N N O Intestinal SN38 H3CH2C SN38-G -glucuronidase SN38-G OH O (active)
    34. 34. Irinotecan Metabolism & Toxicity CH2CH3 XHO O N CH2CH3 N UGT 1A1 / 7 / 9 O GLUCURONIDE O O H3CH2C NSN38 OH O Intestinal -glucuronidase N O H3CH2C OH O Detoxification Intestine Diarrhoea Bone Marrow Leukopenia Thrombocytopenia Adverse Reaction Anaemia Other metabolic determinants: Carboxylesterase activity CYP 3A4 inhibition Gut transporters Enzyme activity in tumour
    35. 35. Systemic chemotherapy causes hepatotoxicity Normal Steatohepatitis (Irinotecan)• 19-79% incidence of sinusiodal injury with oxaliplatin vs 5FU alone• steatosis 30-47% patients treated with 5FU• Irinotecan ~20% incidence of steatohepatitis vs 4.4%• ~15% increase in 90 day mortality with SOS (Oxaliplatin) steatohepatitis
    36. 36. Chemotherapy-induced liver damage Oxaliplatin IrinotecanSinusoidal obstruction syndrome causes Steatohepatitis causes an increase in 90increased operative bleeding but no day operative mortalityincrease in operative mortality ‘Blue’ liver ‘Yellow’ liver
    37. 37. Systemic chemotherapy causes hepatotoxicity Steatohepatitis (Irinotecan) Steatosis • Impaired hepatic defence • Enhanced oxidative stress • BMI is an independent risk factor in steatohepatitis
    38. 38. Systemic chemotherapy causes hepatotoxicity SOS (Oxaliplatin) • Drug kills endothelial cells • Leads to sinusoidal disruption • Activation of hepatic stellate cells • Matrix deposition • Sloughing of erythrocytes & blebbing of cytoplasmic processes
    39. 39. Conclusions Understanding the complex mechanisms of DILI requires an integrated bioanalytical approach – DMPK, genomics, metabolomics & proteomics Understanding mechanisms of DILI will assist with Identifying biochemical risk factors Developing biomarkers of efficacy & toxicity Using potentially toxic drugs more safely Off-target idiosyncratic drug toxicity cannot be predicted from the chemistry of the drug and/or its metabolite because such reactions are by definition (largely) a function of the biology of the individual. Occurrence, Frequency & Severity of Drug Hepatotoxicity = f1 Chemistry of drug + f2 Biology of individual
    40. 40. AcknowledgementsRob JonesNeil Kitteringham