SNPs and Drug Interactions

Transkript

1 SNPs and Cancer

2 SNPs and Drug Interactions Drug Absorption in the breast Drug in breast tissue Metabolism in the liver Transportation in the blood Drug in bloodstream Transporter Drug becomes inactive or toxic Excretion in the kidney

3 SNPs May Be the Solution SNPs A SNPs B SNPs C SNPs D

4 KANSER FARMAKOGENTİĞİ Kemoterapi Rejimi vücut yüzey alanına göre Neden kanser tedavileri başarısız olabiliyor? Tümör hücrelerinin ilaca azalmış hassasiyeti, ilaca karşı direnç gelişimi - doğal veyaprimer rezistans - kazanılmış veya sekonder rezistans (kemoterapiden sonra da gelişebilir) Tedavi (Eş zamanlı ilaç kullanımı) Genetic polimorfizm - İlaç metabolize eden enzimler - ilaç hedef molekülleri (enzimler, reseptörler)

5 Genotyping tests in clinical oncology I- Gene polymorphisms for toxicity of chemotherapeutics 5-FU,irinotecan, thiopurin DPD, UDP glucuronyltransferase, thiopurin S methyl transferase, metabolysing enzymes for purin-pyrimidin analogs, folat metab. enzymes, CYP enz (CYP2B6, CYP2C8, CYP3A), transferases, transport proteins, receptors 2- Tests for response to molecular therapeutics Imatinib- BCR- ABL gene mutations Rituximab- FCGR3A and FCGR2A gene mutations Gefitinib- EGFR gene mutations Trastuzumab- HER2 expression Cisplatin- ERCC1 ve BRCA1 mutation

6 Examples of Valid Genomic Biomarkers Label Context Biomarker Her2/neu Overexpression Representative Label Test Drug Overexpresion of Her2/neu necessary for selection of patients appropriate for drug therapy 1 Trastuzumab (Herceptin) UGT1A1 Variants EGFR expression UGT1A1 mutation in patients, exposure to drug and hence their susceptibility to toxicity 2 Epidermal Growth Factor Receptor presence or absence- 3 Irinotecan (Campto) Cetuximab Gefitinib(Iressa) Erlotinib (Tarceva)

7 Kanser ilaçlarının metabolizması ile ilişkili enzimler ve genler Tiopurin metil transferaz (TMPT) Dihidropirimidin dehidrogenaz (DPD) Sitokrom p 450 (CYP) 5,10 metiltetrahidrofolat redüktaz (MTHFR) N-asetil transferaz (NAT) UDP glukoroniltransferaz (UGT1 ve UGT2) Multi-drug direnç geni (MDR1) DNA hasar onarım geni(ercc1) Sulfotransferaz SULT1A1)

8 Onkolojide kullanılan farmakogenetik testler GEN İLAÇ SONUÇ TMPT (Tiopurin S-metil Transferaz) 6-MP Lösemide etkinlik ve yan etki DHD (DihidropirimidinDehidrogenaz) MTHFR (5-10 metilen tetrahidrofolatreduktaz TSER(TS) (Timilat sentaz) 5-FU 5-FU toksisitesi UGT1A1 (UDP-Glukuronozil Transferaz) irinotekan Metabolizma ve toksisite ERCC1 (Nükleotid eksizyon tamir genleri) GST (Glutatyon S-transferazlar) CYP2D6 (Sitokrom p450 enzimleri) platinum TMX (Tamoksifen) Tümör cevabı ve sağkalımda azalma Adjuvan sonuçları etkiler MTHFR (5-10 metilen tetrahidrofolatreduktaz) MTX (Metotreksat) 5-FU Toksisite riski artar

9 Kemoterapötiklerin Toksisitesinin Belirlenmesinde Kullanılan Testler ve Kanser Tedavisinde Sıklıkla Kullanılan İlaçları Metabolize Eden Enzimler 1. Pürin-pirimidin analoglarını metabolize eden enzimler 2. Folat metabolizmasında görevli enzimler, 3. Sitokrom P450 enzimleri (CYP 450) 4. Transferazlar, 5. Taşıyıcı proteinler, 6. Reseptörler.

10 Pürin-pirimidin analoglarını metabolize eden enzimler Tiopurinler: losemi tedavisinde yaygın olarak kullanılan ilaclardır. - merkaptopurin: ALL (akut lenfoblastik lösemi) - Tioguanin: AML (akut myeloblastik lösemi) - Azotiopürin:immün baskılayıcı (Crohn hastalığının tedavisi)

11 Tiopurin S-metil transferaz (TPMT) Tiopürinlrin terapötik etkinliği ve toksisitesinden sorumlu TPMT genindeki polimorfizmler TPMT enzim aktivitesini azaltır TPMT aktivite azalması : ciddi, hayatı tehdit eden toksisiteler

12 TPMT ve Merkaptopurin Tedavisi 6-MP; ALL tedavisinde kullanılan ön ilaç 6-MP transferaz hypoxantine guanin phosphorybosyl (6 thioguanine oluşur) tarafından aktive olur TPMT inactivates 6-MP by S methylation 6-MP TPM tarafından S metilasyon ile inaktive olur inaktif ön-ilaç 6-Mercaptopurin *Polymorp. TPMT 6-MeMP (inactive) HPRT Thioguanin nucleotids Antitumor effect Myelosupression TPMT = Tiyopürin metiltransferaz / 6-MeMP = 6-metil merkaptopürin HPRT = Hipoksantin fosforibozil transferaz : Biochimica et Biophysica Acta, 1603 (2003)

13 Tiopurin metil transferaz Doğal tipi TPMT1 Alelleri :5 adet aleli mevcut TPMT2,TPMT3A,TPMT3B,TPMT3C, TPMT4 Alellerin 3 ü %95 i kapsar Kişilerin %10 unda aktivite az, %3 ünde hiç yok heterozigotlar dozun %65 ini tolere edebilir, homozigotlar toksisiteden ölür. Bu varyantlar nedeniyle doz indirimi yapılan hastalarda sağkalım= doğal tip alel taşıyıcıları

14 Genotype-Guided 6-MP Dosing Pharmacogenomics 2002;3(1):89-98.

15 Genetic polymorphism of TPMT activity and thiopurine therapy Krynetski & Evans, Am J Hum Genet :11-16

16 Prevalence of TPMT Genotypes- Three Major SNPs (single gene) Define Mutant Alleles Newly Diagnosed ALL Patients per Year 30,000 Homozygotes 100 None or Low TPMT Activity Heterozygotes 3,300 Intermediate TPMT Activity Wild Type 26,600 High TPMT Activity Two Mutant Alleles v/v One Mutant Allele wt/v No Known Mutation wt/wt

17 Pharmacogenetics: Use in drug delivery ALL, 6MP and polymorphic TPMT 6MP Children TPMT Toxicity 6MP Children TPMT Poor response

18 HERCEPTIN

19 Oncology Breast Cancer 25-30% of breast and ovarian tumors overexpress HER2 Overexpression is correlated with prognosis Patients positive for HER2 can be treated with Herceptin Herceptin is a monoclonal antibody against the HER2 receptor Improved survival

20 Examples pharmacodynamics Breast Cancer abnormally high amounts of HER2 protein in 30% of patients Herceptin binds to HER2 slowing tumour growth, 70% of patients do not respond

21 HER-2 Protein and Herceptin Herceptin (trastuzumab): Metastatic breast cancer Targets tumor cells that over-express the human epidermal growth factor receptor 2 (HER2) protein Best response attained in women who over-express the HER2 protein HER-2 over-expression in breast cancer cells should be done before patients receive the drug

22 Herceptin: Prescribing Information HERCEPTIN (Trastuzumab) as a single agent is indicated for the treatment of patients with metastatic breast cancer whose tumors overexpress the HER2 protein and who have received one or more chemotherapy regimens for their metastatic disease. HERCEPTIN should be used in patients whose tumors have been evaluated with an assay validated to predict HER2 protein overexpression

23 Pharmacogenetics = molecular DD Case Study: Herceptin Bimodal response: 2/3 of patients: addition of Herceptin to chemorx no benefit 1/3 of patients: addition of Herceptin to chemorx 50% survival time increased by factor 1.5 (20 29 weeks) High HER2 Low HER2

24 5 fluorouracil and DPD

25 5 fluorouracil and DPD 5-FU may cause serious gastrointestinal and hematologic side effects (3-5%). 5-FU causes grade 4 neutropenia in pts with DPD deficiency (40-50%)

26 prodrug Polymorphism in 5-fluorouracil (5-FU) Metabolism 5-FU (TP) thymidin phosphorilase (activation) Active metabolit 5-floro 2 deoksiuridin monofosfat (FdUMP) DPD (detoksification) DPD polymorphism neurologic toxicity GI toxicity hematologic toxicity MTHFR polymorphism low MTHFR activity 5-FU efficacy increase MTHFR İnactive metabolite TS TS polymorphism TS activity increases 5-FU efficacy decreases TRENDS in Pharmacological Sciences, 25 (2004)

27 Tamoxifen Pro-drug widely used treatment in breast cancer patients inhibits estrogen from binding to its receptor, thus inhibiting estrogen-regulated genes (growth factors and angiogenic factors) metabolized by cytochrome P450s into N- desmethyltamoxifen (NDM), 4- hydroxytamoxifen (4-OH tamoxifen) and endoxifen efficacy of tamoxifen therapy among women is heterogeneous due to genetic variants of CYP2D6

28 On October 18 (2006), a presantation of the study related to Tamoxifen by Dr. Goetz to the FDA led to an advisory committee unanimously recommending a label chance for tamoxifen. This change would include information about the incresaded risk both from genetic factors and drug interactions affecting CYP2D6. The majority of the committee also recommended that CYP2D6 genotype testing as an option for women before they are prescribed tamoxifen.

29 Tamoxifen Biotransformation Jin et al., J. Natl. Cancer Inst. 97:20-39, 2005.

30 Tamoxifen Pharmacogenomics Breast Cancer (190 Patients) Relapse Free Survival, % Disease Free Survival Goetz et al., Breast Cancer Res. Treat. 101: , 2007.

31 Relapse-Free (RF) Probability by CYP2D6 Genotype No Tamoxifen Tamoxifen Tamoxifen Schroth et al., JCO 25: , 2007

32 Selective Serotonin Reuptake Inhibitors (SSRIs) & Tamoxifen antidepressants that are often prescribed to treat hot flashes in women who take tamoxifen paroxetine, sertraline, citalopram, fluoxetine and venlafaxine inhibition of CYP2D6 by SSRIs likely to affect metabolism of tamoxifen use of SSRIs associated with a reduced mean plasma concentration of endoxifen (lower response to tamoxifen therapy)

33 Results with inhibitor without inhibitor Jin et al., 2005

34 Objectives examine association between genotype (CYP2D6) and plasma concentrations of tamoxifen and its metabolites examine effect of CYP2D6 inhibitors on plasma concentrations of endoxifen examine SSRIs and their association with plasma concentrations of endoxifen

35 Mary 55 years PHARMACOGENETICS Drug gene interactions Tamoxifen+CYP2D6 Carol 55 years CYP2D6 PM CYP2D6*4/*4 CYP2D6 EM OK CYP2D6*1/*1!!! Noeffects, risk of disease relapse Improved benefit from tamoxifen

36 Conclusion & Significance higher plasma endoxifen concentration than 4- OH tamoxifen may mean it has a more important role efficacy of tamoxifen therapy among women is heterogeneous due to genetic variants of CYP2D6 use of SSRIs associated with a reduced mean plasma concentration of endoxifen (lower response to tamoxifen therapy)

37 PROJECT Pharmacogenomic and Nutrigenomic Enhancement of CYP2D6 Activity in Tamoxifen-Resistant Breast Cancer Patients in Turkish, French &Canadian Patients Presley JF 1, Bernard-Gallon D 2, Genç E 3, Kilic U 3, Dejgaard SY 1, Yeliz Demirci 3, Bignon YJ 2, Hizel C 1, 2, 3,4 Study Objective/ Hypothesis to develop an integrated pharmacogenomic & nurigenomic approach to tamoxifen therapy to gain the capability to significantly improve this outcome with targeted and inexpensive nutritional modification which can alter the expression level of CYP2D6 in IMs. Hypothesis nutritional interventions that improve metabolism of tamoxifen will significantly improve survival rates of IM breast cancer patients. 1)Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada H3A2B2, 2) Département d'oncogénétique du Centre Jean Perrin, Clermont-Ferrand Cedex 01, France 3)Department of Biochemistry, Faculty of Medicine, Yeditepe University, Istanbul,Turkey. 4) C2H-Vichy Genomics, Vichy,France

38 References Garber, K. (2005) J. Natl. Cancer Inst. 97: Jin, Y. et al. (2005) J. Natl. Cancer Inst. 97: Osborne, C.K. (1998) N. Eng. J. Med. 339: Stearns, V. et al. (2003) J. Natl. Cancer Inst. 95:

39 Irinotecan (CPT-11) Pro-drug FDA approved & widely used in treatment of metastatic colorectal cancer Topoisomerase I inhibitor Complex metabolic pathway Wide interindividual variability in drug response and in occurrence of toxic side-effects (severe diarrhea, neutropenia, myelosuppression).

40 Polymorphisms that affect irinotecan therapy Relling & Dervieux, Nature Cancer Reviews 1:99-108

41 Glucuronide Formation Rate Genotype Versus Phenotype Genotype and Phenotype Genotype Glucuronidation 6/6 851±545 6/7 699± UGT1A1*28 Genotype and Estradiol Glucuronidation 7/7 199±118 Mean ± Standard Deviation /6 6/7 7/7 Genotype Fisher et al. Pharmacogenetics, 2000

42 Current Understanding of PGx and Neutropenia Group Prevalence Risk of Toxicity All Patients % Patients That Are 7/7 Patients That Are 6/7 Patients That Are 6/6 10% 50% 40% 12.5% 50% 0% Based on data from Innocenti et al (2004)

43 Potential of UGT Testing to Inform Dosing All Patients with Same Diagnosis PGx profile for high risk (50%): treat with alternative drug or dose PGx Profile for moderate risk (12.5%): treat with alternative drug or dose PGx Profile for low risk (0%): treat with conventional dose

44 Conclusions UGT1A1 genotype (UGT1A1*28)and total bilirubin levels are strongly associated with severe diarrhea & neutropenia. UGT 1A1*28 is a variant allele» Variation in the TA repeats in the promoter region Normal allele: 6 TA repeats (6/6) Variant allele: 7 TA repeats (7/7) UGT 1A1*28 is associated with reduced gene expression and reduced glucuronidation in human liver microsomes. Grade 4 neutropenia is more common (p=0.001) in patients with 7/7 genotype patients A strong correlation between genotype and diarrhea (P=0.01)

45 Utility of UGT1A1 Polymorphism in the Use of Irinotecan Excluding 7/7 patients from standard dose of irinotecan treatment will reduce the overall incidence of grade 4 neutropenia from 10.1% to 5.7%. 7/7 genotype patients may get a alternate irinotecan regimen? Genotypic testing combined with bilirubin levels will allow better patient selection for Irinotecan therapy. Physicians will be better informed about use of Irinotecan as a single agent or in combination therapy. Genotypic testing will allow 7/7 genotype patients with a choice for equally efficacious alternate therapy.

46 6-Mercaptopurine (6MP) and Childhood Acute Lymphoblastic Leukemia (ALL) ALL is a life-threatening disease and 6MP can cause life-threatening toxicities Dose titration (dosing size, duration and intensity) is major determinant of long-term EFS and myelosuppressive effects 6MP is metabolized to pharmacologically active thiopurine nucleotides by thiopurine methyltransferase (TPMT) TPMT activity shows trimodal variation in the general population

47 TPMT Genetic Polymorphism Well-documented, causal link between TPMT polymorphism and clinical effects, including toxicity Genotypes with reduced (10% of the population) or no (0.3% of the population) activity are at a substantially increased risk of myelosuppression and secondary cancer Pharmacogenetic tests are available and feasible to use for identifying these patients and guide optimal dosing

48 CYP2D6 and Metabolism of Tamoxifen CYP2D6 enzyme activity directly related to: Common genetic polymorphisms