Effect of SULT1A1, UGT2B7, CYP3A5 and CYP2D6polymorphisms on tamoxifen response in breast cancer patients of Bangladesh

Abstract

Breast cancer is the leading cause of cancer death in females worldwide as well as in Bangladesh. Tamoxifen (TAM), selective estrogen receptor modulators (SERMs), is the most commonly used agent for the treatment of estrogen receptor positive breast cancer patients as adjuvant therapy which reduces the risk of recurrence and prolongs the survival. Though most patients are benefited from TAM, some are either fail to respond or become resistant. Tamoxifen is metabolized via the cytochrome P450-mediated pathway and metabolites are inactivated by sulfotransferases 1A1 (SULT1A1), or by the UDP-glucuronosyltransferases (UGT).This study aimed to investigate the prognostic and/or predictive value of functional polymorphisms in SULT1A1,UGT2B7,CYP3A5 and CYP2D6 in Tamoxifen-treated breast cancer patients to correlate the genotype data pharmacogeneticaly with Response, Survival Rate (SR), Hazard Ratio (HR), Breast Cancer Specific Survival (BCSS) and Recurrence Free Survival (RFS). Methods: A total three hundred and eighty eight estrogen receptor positive female patients with invasive breast cancers and taking Tamoxifen 20mg/day orally for 8 weeks or more were recruited from different public and private hospitals of Bangladesh.The study was conducted in accordance with the International Conference of Harmonization (ICH) for Good Clinical Practice (GCP) and in compliance with the Declaration of Helsinki .Ethical permission was taken to approve the protocol. Each volunteer signed an informed consent document before entering the study.The American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system (sixth edition) and Response Evaluation Criteria In Solid Tumors (RECIST) were used to evaluate the pathological response of primary tumor and axillary lymph nodes and the assessment of chemotherapy induced toxicity was done with the help of Common Terminology Criteria for Adverse Events (CTCAE) v4.Performance status was done by ECOG Performance Statusdeveloped by the Eastern Cooperative Oncology Group, Robert L. Comis, MD, Group Chair.Genomic DNA was isolated by using Daly’s Method (Daly et al., 1998). Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method was used to analyze the genetic polymorphisms.Amplified DNA fragments was digested by restriction enzymes followed by gel electrophoresis to identify the targeted alleles namely SULT1A1*2, UGT2B7*2, CYP3A5*3, CYP2D6*10 and CYP2D6*4. Results:Bangladeshi breast cancer patients showed variable Tamoxifen treated response data in the study.Patients carrying mutant homo(AA) genotype (aOR=2.358 and p=0.0058)and hetero(GA) genotype(aOR=2.933 and p=3.97E-05) showed good response in comparison to Wild(GG) genotype. Patient having hetero(CT) polymorph of UGT2B7*2 also showed prominat(aOR=4.213 and p=0.0001) response in comparison to normal(CC) polymorph. Those patients who have hetero(AG) polymorph of CYP3A5*3 also showed statistically significant result(aOR=5.626 and p˂0.0001) in comparison normal homozygote(AA).Both hetero(CT) and mutant homo(TT) showed significant result(aOR=29.082 & p˂0.0001 and aOR=1.33E+15 & p˂0.0001,respectively) for Tamoxifen associated response among Bangladeshi breast cancer patients. Other polymorphism of selected genes did no show any significant result. Patients carrying hetero(CT) polymorph of CYP2D6*10 showed significant relationship with hot flashes toxicity(aOR=8.40E+07 & p=0.0479) in comparison to wild(CC) genotype. Those breast cancer patients who had hetero(CT) polymorph(aOR=2.61 & p=0.033) of UGT2B7*2 and both hetero(CT)(aOR=1.77E+08 & p=0.0223) & mutant homo(TT)(aOR=2.32E+08 & p=0.0117) polymorphs of CYP2D6*10 showed significant depression in comparison to wild CC for UGT2B7*2 and CC for CYP2D6*10.Both hetero(GA)(aOR=1.58E+07 & p=0.0215) and mutant homo(AA)(aOR=6.31E+06 & p=0.0017) of SULT1A1*2 were found significantly related with Tamoxifen associated decreased libido in comparison to wild(GG) genotype.Hetero(CT) polymorphs of UGT2B7*2 also showed significant relation(aOR=6.34E+06 & p=0.0054) with depression in comparison to wild(CC) genotype. Both hetero(CT)(aOR=4.27E+06 & p=0.0070) and mutant homo(TT)(aOR=6.44E+06 & p=0.0027) polymorphs of CYP2D6*10 showed significant relation with depression in comparison to normal(CC) genotype.Both hetero(CT)(aOR=1.47E+08 & p=0.0364) and mutant homo(TT)(aOR=1.59E+08 & p=0.0255) polymorphs of CYP2D6*10 showed significant relation with vaginal dryness in comparison to normal(CC) homozygote. No other polymorphs of selected genes showed relationship with these toxicity responses.Patents carrying both hetero(GA)(OR=21.5680 & p=0.0364) and mutant homo(AA)(OR=24.9813 & p=0.0255) polymorphs of SULT1A1*2 showed significant relation with Hazard ratio≤1.5 in comparison to wild(GG) genotype. Hetero polymorph(CT) of UGT2B7*2 carrying patients showed significant relation(OR=4.6445 & p˂0.0001) with Hazard ratio≤1.5 in comparison to wild CC genotype. Hetero polymorph(AG)(OR=5.5577 & p=0.0002) of CYP3A5*3 carrying patients had significant relation with Hazard ratio≤1.5 in comparison to wild(AA) genotype. Both hetero(CT)(OR=210.9091 & p˂0.0001) and mutant homo(TT)(OR=28357.6667 & p˂0.0001) of CYP2D6*10 showed significant result in relation to Hazard ratio≤1.5 in comparison to wild(CC) genotype.Mutant homo(TT) genotype of UGT2B7*2 showed significant relation(OR=4.0906 & p=0.0004) with survival rate˃5 years in comparison to wild(CC) genotype patients.Mutant homo(GG) of CYP3A5*3 polymorph showed significant relation(OR=7.7834 & p˂0.0001) with survival rate˃5 years in comparison to normal(AA) genotype.Both hetero(GA)(OR=17.2757 & p˂0.0001) and mutant homo(AA)(OR=6.7143 & p=0.0062) of CYP2D6*4 were found significant relationship with survival rate˃5 years in comparison to wild(GG) genotype. Recurrence free survival˃5 years was associated significantly among breast cancer patients with CYP2D6*10 mutant homo(TT)(OR=1.8645 & p=0.0107) in comparison to normal(CC) genotype.Mutant homo(GG) of CYP3A5*3 found strongly related(OR=192.0737 & p=0.0002) with breast cancer specific survival in comparison to normal(AA) genotype. Both hetero(GA)(OR=55.1209 & p˂0.0001) and mutant homo(AA)(OR=27.5137 & p=0.229) polymorphisms of CYP2D6*4 found significant relation with breast cancer specific survival in Bangladeshi patients in comparison to normal(GG) genotype. No other polymorphs of our selected gene were found significantly associated with survival data. We did not find any correlation between performance status and SULT1A1*2, UGT2B7*2,CYP3A5*3,CYP2D6*4 and CYP2D6*10 genotype among Tamoxifen treated Bangladeshi breast cancer patients. Conclusion:A,T,G,A and T allele of SULT1A1*2,UGT2B7*2,CYP3A5*3,CYP2D6*4 and CYP2D6*10 respectively found significant in Tamoxifen treated respone,survival,toxicity and performance status variability among Bangladeshi breast cancer patients.It is important to identifying such patients before the start of treatment in optimizing therapy with Tamoxifen. The finding of this research work has detected the actual causes of the development of side effects, response variability, survival difference and performance diversity after Tamoxifen therapy in Bangladeshi breast cancer patients and suggest the alternative treatment therapy for the disease at early stage and help to develop a safe, efficient and cost effective treatment plan for the patients.