THE PHARMACOGENOMICS OF VINCRISTINE-INDUCED NEUROTOXICITY
IN PAEDIATRIC CANCER PATIENTS WITH WILMS TUMOR OR
RHABDOMYOSARCOMA
by
Tenneille Loo
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE in
THE FACULTY OF GRADUATE STUDIES
(Experimental Medicine)
THE UNIVERSITY OF BRITISH COLUMBIA
(Vancouver)
July 2011
© Tenneille Loo, 2011
Abstract
Vincristine is one of the most effective and widely utilized antineoplastic agents.
However, the clinical utility of this drug is limited by severely debilitating vincristineinduced neurotoxicities (VIN). Previous studies have associated VIN with genetic polymorphisms in genes involved in the metabolism and transportation of vincristine, including CYP3A4, CYP3A5, and ABCB1. However, the findings of such studies have not been consistently reproduced. This study hypothesizes that there are specific variants in genes involved in general drug absorption, metabolism, distribution, excretion, and toxicity (ADME-Tox) that affect the individual susceptibility to VIN in patients with Wilms tumor and rhabdomyosarcoma.
Detailed clinical data was collected from 140 patients with Wilms tumor and rhabdomyosarcoma by retrospective chart review. VIN cases were characterized by type of neurotoxicity, and severity was evaluated using a validated clinical grading system for adverse events (NCI-CTCAE v4.03). A customized Illumina GoldenGate Panel was used to genotype 4,536 single nucleotide polymorphisms (SNPs) in candidate genes involved in the metabolism and transportation pathway of vincristine, as well as in genes broadly involved in ADME-Tox.
None of the SNPs that were previously reported to be associated with VIN were found to be significantly associated (p-value < 0.05). With similar effect sizes, six novel
genetic variants in five genes (PON1, ABCA4, ABCG1, CY51A1, SLCO1C1) were
significantly associated with VIN in both tumor types. Whereas none of these genes have been previously associated with VIN or the biotransformation of vincristine, interestingly,
ii the biological functions of the encoded proteins have been indirectly linked to nerve function, neuropathy, or neurodegenerative diseases. Therefore, I hypothesize that the genetic basis of VIN is likely polygenic and that the six genes influence individual susceptibility to VIN by affecting: nerve regeneration (PON1, PPP1R9A), and cholesterol homeostasis and remyelination (ABCA4, ABCG1, CYP51A1), as well as the metabolism of vincristine (PON1, CYP51A1) and the transportation of lipids, vincristine, metabolites, or neuroprotectants
(SLCO1C1, ABCA4, ABCG1).
This study adds to the literature by identifying new potential biomarkers for VIN, providing novel hypotheses for the mechanisms underlying VIN susceptibility, and is a point of origin for replication studies.
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Preface
The work contained in this thesis has been approved by the University of British
Columbia and the Children’s & Women’s Health Centre of BC Research Ethics Board, the Ethics Certificate Numbers for this study are H10-01568 and H04-70358.
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Table of Contents
Abstract ................................................................................................................................... ii Preface .....................................................................................................................................iv Table of Contents.....................................................................................................................v List of Tables............................................................................................................................x List of Figures .........................................................................................................................xi List of Symbols and Abbreviations..................................................................................... xii Acknowledgements............................................................................................................. xvii Chapter 1: Introduction.........................................................................................................1
1.1 Adverse Drug Reactions...............................................................................................1
1.1.1 Factors that Contribute to Adverse Drug Reactions...............................................2 1.1.2 Adverse Drug Reactions in Children......................................................................2 1.1.3 Pharmacogenomics.................................................................................................4
1.2 Vincristine ....................................................................................................................5
1.2.1 The Antineoplastic Mechanism of Action..............................................................6 1.2.2 Metabolism and Transportation..............................................................................6 1.2.3 Clinical Use of Vincristine in Children ..................................................................9
1.3 Vincristine-Induced Neurotoxicity.............................................................................10
1.3.1 Signs and Symptoms ............................................................................................10 1.3.2 Clinical Diagnosis of Vincristine-Induced Neurotoxicity....................................11 1.3.3 Management .........................................................................................................13 1.3.4 Future Management: Neuroprotectants ................................................................14
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1.3.5 Pathophysiology ...................................................................................................15
1.4 Factors Affecting the Exposure to Vincristine ...........................................................17
1.4.1 Dose Intensity, Frequency, and Cumulative Dose................................................17 1.4.2 CYP3A Inhibitors.................................................................................................19 1.4.3 Genetic Variation in CYP3A4 and CYP3A5, and Ancestry ................................20 1.4.4 Vincristine Transporters .......................................................................................21 1.4.5 Previous Pharmacogenomic Studies.....................................................................22
1.5 Patient Cohort Selection: Wilms Tumor and Rhabdomyosarcoma............................24
Chapter 2: Hypothesis, Project Goal and Objectives........................................................28
2.1 Hypothesis ..................................................................................................................28 2.2 Project Goal and Objectives .......................................................................................28
Chapter 3: Methodology ......................................................................................................29
3.1 Recruitment, Consent, and Establishing Causality.....................................................29 3.2 Defining Cases and Controls......................................................................................31 3.3 Clinical Characterization of Vincristine-induced Neurotoxicity Cases .....................33
3.3.1 Classifying Each Vincristine-Induced Neurotoxicity Event by Type of
Neuropathy ...........................................................................................................33
3.3.2 Evaluating the Severity of Each Vincristine-Induced Neurotoxicity Event.........33
3.4 Study Inclusion and Exclusion Criteria......................................................................40 3.5 Calculating Dose and Time to First Adverse Drug Reaction.....................................41 3.6 Association Studies.....................................................................................................42
3.6.1 General Drug Biotransformation Genotyping ......................................................42 3.6.2 Candidate Gene Analysis......................................................................................43
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3.7 Genotyping: Illumina GoldenGate Assay...................................................................43 3.8 Quality Control and Assurance in Genotypic Data ....................................................44
3.8.1 Quality of Patient Samples and SNPs...................................................................44 3.8.2 Data Cleaning .......................................................................................................45
3.9 Statistical Analyses: Logistic Regression Models and Manhattan Plot .....................46 3.10 Prediction Model ........................................................................................................48 3.11 Linkage Disequilibrium Studies.................................................................................49 3.12 Imputation Analyses...................................................................................................49
Chapter 4: Results ................................................................................................................51
4.1 Patient Cohort.............................................................................................................51 4.2 Patient Demographics and Clinical Factors................................................................52 4.3 Assessing the Severity and Types of Vincristine-Induced Neurotoxicity and the
Interventions Provided ...............................................................................................55
4.4 Variation by Ancestry.................................................................................................60 4.5 Genetic Analyses........................................................................................................62
4.5.1 Screening for Genes Involved in the General Drug Biotransformation Pathways
.............................................................................................................................63
4.5.2 Candidate Study....................................................................................................78
Chapter 5: Discussion...........................................................................................................84
5.1 The Incidence of Vincristine-Induced Neurotoxicity.................................................84 5.2 Clinical Factors...........................................................................................................85
5.2.1 Age........................................................................................................................85 5.2.2 Tumor Type ..........................................................................................................87
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5.2.3 Ancestry................................................................................................................88 5.2.4 Concomitant Medications: Steroids and CYP3A4 Inhibitors...............................88
5.3 Vincristine-Induced Neurotoxicity: Types of Neurotoxicity and Severity ................89 5.4 Novel Genes and Genetic Variants Potentially Associated with Vincristine-Induced
Neurotoxicity..............................................................................................................90
5.4.1 PON1 (Paraoxonase 1) and PPP1R9A (Neurabin 1)............................................92 5.4.2 ABCA4, ABCG1, and CYP51A1 .........................................................................102 5.4.3 SLCO1C1............................................................................................................108
5.5 Previously Identified Polymorphisms and Candidate Genes Involved in the
Biotransformation of Vincristine .............................................................................108
5.5.1 CYP3A5 and CYP3A 4.........................................................................................110 5.5.2 ABCB1 ................................................................................................................111 5.5.3 Other Candidate Genes.......................................................................................112
5.6 Inter-Ethnic Differences ...........................................................................................113 5.7 Limitations................................................................................................................114 5.8 Future Directions......................................................................................................116
5.8.1 Expansion, Replication, and Validation of Novel SNPs and Genes...................116 5.8.2 Detailed Genetic Investigation of Novel Candidate Genes................................117 5.8.3 Pharmacokinetic and Functional Validation Studies..........................................118
5.8.3.1 PON1 (Paraoxonase 1) and PPP1R9A (Neurabin 1)...................................119 5.8.3.2 ABCA4, ABCG1, and CYP51A1: Cholesterol Biosynthesis and Intracellular
Transport......................................................................................................120
5.8.3.3 Metabolizers and Transporters ....................................................................121
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5.8.4 Investigation of Additional Genes Potentially Involved in VIN ........................121 5.8.5 Observational Trials............................................................................................123
5.9 Future Implications...................................................................................................123
Chapter 6: Conclusion........................................................................................................126 References.............................................................................................................................128
Appendix A........................................................................................................................139
A.1 Excluded SNPs: Less than 98% Completion Rate Across Patients.....................139 A.2 Excluded SNPs: Hardy-Weinberg Disequilibrium..............................................140 A.3 Significant SNPs in the ADME-Tox Panel of General Drug Biotransformation141
A.4 PON1, ABCA4, SLCO1C1, CYP51A1, and ABCG1 Risk Alleles Increase the
Chances of Developing Vincristine-Induced Neurotoxicity...............................146
A.5 Imputed Regions with Base Pair Limits Used.....................................................147 A.6 Manhattan Plot for Imputed SNPs.......................................................................148
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List of Tables
Table 1 Grading Vincristine-Induced Neurotoxicity with the CTCAE Criteria (v4.03)....34 Table 2 Grading Vincristine-Induced Neurotoxicity by Intervention ................................38 Table 3 Patient Demographics and Clinical Factors Between Cases and Controls............53 Table 4 Vincristine-Induced Neurotoxicity and the Interventions Provided to Wilms
Tumor and Rhabdomyosarcoma Cases ................................................................56
Table 5 The Frequency of Each Type of Vincristine-Induced Neurotoxicity Sign or
Symptom...............................................................................................................58
Table 6 Genetic Variants that are Significantly Associated with Vincristine-Induced
Neurotoxicity........................................................................................................65
Table 7 Subgroup Analysis of Genetic Variants that are Significantly Associated with
Vincristine-Induced Neurotoxicity: Stratification of Patients by European Ancestry................................................................................................................69
Table 8 Linkage Disequilibrium of SNP Pairs: PON1, PPP1R9A, PON1, and ABCA 4....71 Table 9 PON1 rs854549, PPP1R9A rs705377, and PON1 rs854560 and their Association with Vincristine-Induced Neurotoxicity...............................................................76
Table 10 The Effects of SNPs Previously Identified to be Associated with Vincristine-
Induced Neurotoxicity ..........................................................................................79
Table 11 The Effects of Previously Identified Genes Involved in the Metabolism and
Transportation Pathway of Vincristine.................................................................82
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List of Figures
Figure 1 The Pharmacokinetics and Pharmacodynamics of Vincristine...............................7 Figure 2 Ethnic Distribution of the Patients in the Cohort..................................................60 Figure 3 Manhattan Plot ......................................................................................................63
- Figure 4
- SNP Clusters of PON1 rs854549, ABCA4 rs3789433, SLCO1C1 rs10770704,
ABCG1 rs221948, CYP51A1 rs7797834, and ABCA4 rs549848..........................66
Figure 5 PON1, ABCA4, SLCO1C1, CYP51A1, and ABCG1 Risk Alleles Increase the
Chances of Developing Vincristine-Induced Neurotoxicity.................................69
Figure 6 Linkage Disequilibrium Plot of PON1, PPP1R9A, and the Intergenic Region in the European (CEU) Hapmap Populations...........................................................71
Figure 7 Linkage Disequilibrium Plot of PON1, PPP1R9A, and the Intergenic Region in the African (YRI) Hapmap Populations ...............................................................72
Figure 8 Linkage Disequilibrium Plot of PON1, PPP1R9A, and the Intergenic Region in the Asian (CHB, JPT) Hapmap Populations.........................................................73
Figure 9 SNP Clusters of PPP1R9A rs705377 and PON1 rs854560 ..................................76 Figure 10 Clustering of Candidate SNPs: CYP3A5 and CYP3A4........................................79 Figure 11 Clustering of Candidate SNPs: ABCB 1...............................................................80 Figure 12 The Theorized Role of the Novel Genes in the Metabolism and
Biotransformation of Vincristine..........................................................................90
Figure 13 Chemical Structures of Methyl Phenylacetate, Vincristine, and Clopidogrel......96 Figure 14 Cholesterol Biosynthesis ....................................................................................103
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List of Symbols and Abbreviations
ABCA4 ABCB1
ATP-binding cassette, sub-family B, member 4; multidrug resistance protein 3 ATP-binding cassette, sub-family B, member 1; multidrug resistance protein 1; P-glycoprotein
ABCB4 ABCC1
ATP-binding cassette, sub-family B, member 4; multidrug resistance protein 4 ATP-binding cassette, sub-family C, member 1; multiple drug resistance protein 1
ABCC2
ABCC3 ABCC4 ABCC5 ABCC6 ABCC7 ABCC8 ABCC10
ATP-binding cassette, sub-family C, member 2; multiple drug resistance protein 2 ATP-binding cassette, sub-family C, member 3; multiple drug resistance protein 3 ATP-binding cassette, sub-family C, member 4; multiple drug resistance protein 4 ATP-binding cassette, sub-family C, member 5; multiple drug resistance protein 6 ATP-binding cassette, sub-family C, member 6; multiple drug resistance protein 6 ATP-binding cassette, sub-family C, member 7; multiple drug resistance protein 7 ATP-binding cassette, sub-family C, member 8; multiple drug resistance protein 8 ATP-binding cassette, sub-family C, member 10; multiple drug resistance protein 10
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ABCG1 ADL
ATP-binding cassette, subfamily G, member 1 Activities of Daily Living
- ADME
- Absorption, Distribution, Metabolism, and Excretion
ADME-Tox Absorption, Distribution, Metabolism, Excretion, and Toxicity ADR ALL
Adverse Drug Reaction Acute Lymphoblastic Leukemia
- Amyotrophic Lateral Sclerosis
- ALS
- AN
- Autonomic Neuropathy
- ANS
- Autonomic Nervous System
AUC BSA
Area-Under-the-Concentration Body Surface Area
- CEU
- Northern and Western European Ancestry (Utah, United States)
Han Chinese Ancestry (Beijing, China) Chinese Ancestry (Denver, Colorado) Confidence Interval
CHB CHD CI CMT CNS
Charcot Marie Tooth Central Nervous System
COG CPNDS CTEP CTCAE CYP450 CYP3A4
Children’s Oncology Group Canadian Pharmacogenomics Network for Drug Safety Cancer Therapy Evaluation Program Common Terminology Criteria for Adverse Events Cytochromes P450 Cytochrome P450, family 3, subfamily A, polypeptide 4
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- CYP3A5
- Cytochrome P450, family 3, subfamily A, polypeptide 5
Cytochrome P450, family 51, subfamily A, polypeptide 1; Lanosterol; 14-α- Demethylase
CYP51A1 DNA DTR
Deoxyribonucleic Acid Deep Tendon Reflex
GWAS HDL HWE IADL IBS
Genome-Wide Association Studies High-density Lipoprotein Hardy-Weinberg Equilibrium Instrumental Activities of Daily Living Identity-by-State
- IBD
- Identity-by-Descent
IGF-1 JPT
Insulin-like Growth Factor 1 Japanese Ancestry (Tokyo, Japan)
- Linkage Disequilibrium
- LD
m-ABC MAF MAPT MAP2 Nb1
Motor Assessment Battery for Children Minor Allele Frequency Microtubule-Associated Protein Tau Microtubule-Associated Protein 2 Neurabin 1 ncRNA NCS
Non-Protein-Coding RNA Nerve Conduction Studies
NCI-CTCAE National Cancer Institute – Common Terminology Criteria for Adverse Events NGF Nerve Growth Factor