Predictive Role Of TGFBR2 Gene Ploymorphysoms On Advanced NSCLC Treated With Platinum-based

Non-small cell lung cancer (NSCLC) accounts for approximately 80% of such deaths. Most NSCLC patients are diagnosed in the advanced (stage III or IV) stages. Five-year survival rates for NSCLC remain less than 15%. Standard treatment for NSCLC involves chemotherapy with a platinum agent and another cytotoxic agent. Recent clinical studies suggest a large potential for genomic findings in treatment outcome predictions. It is widely recognized that genetic polymorphisms in genes for drug transport, drug metabolizing, DNA repair and apoptosis often play important roles in the variability of cytotoxic chemotherapy toxicity outcomes. In this study, we focused on transforming growth factor, beta receptor II (TGFBR2), being important in cell proliferation and apoptosis.Purpose: to investigate the association between TGFBR2 polymorphisms and the incidence of adverse events in advanced non-small cell lung cancer (NSCLC) patients receiving first-line platinum-based chemotherapy through mRNA expression.Patients and Methods: A retrospective pharmacogenetic association study was performed in 1004 Chinese patients with advanced NSCLC receiving platinum-based regimens (including 221 treated with cisplain-navelbine, 195 with cisplatin-gemcitabine, 190 with carboplatin-paclitaxel, and 108 with cisplatin-paclitaxel). Information about grade 3 or 4 overall toxicity, gastrointestinal toxicity (nausea/vomiting) and hematologic toxicity (neutropenia, anemia, thrombocytopenia) was available. 34 tag single nucleotide polymorphisms (SNPs) of TGFBR2 were assessed.PATIENTS AND METHODS:Study design and patients recruitment. All patients enrolled in the study were Chinese, and had histologically diagnosed stage IIIA-IV NSCLC at Shanghai Chest, Shanghai Zhongshan and Shanghai Changhai Hospitals between March 2005 and January 2010. Patient responses to the treatment were evsluated after first two courses by the Response Evaluation Criteria in Solid Tumors(RECIST) guideline, which classify Patient responses to the treatment were evaluated after first two courses, which classify the responses into four categories: complete response (CR),partial response (PR), stable disease88 (SD), and progressive disease (PD). For the data analysis, CR and PR were combined as responders, and SD and PD were grouped as non-responders. Chemotherapy toxicity was assessed twice weekly and graded according to the National Cancer Institute Common Toxicity Criteria version 3.0. Toxicities included neutropenia, anemia, thrombocytopenia, nausea, and vomiting. Severe hematologic toxicity included grade 3 or 4 neutropenia, anemia, or thrombocytopenia. Severe gastrointestinal toxicity included grade 3 or 4 nausea or vomiting. Severe overall toxicity included grade 3 or 4 hematologic or gastrointestinal toxicity. The complete medical record (including progress notes of the treating oncologist and nurses) was available and reviewed. Investigators were blinded to the genotype status of the patients. Chemotherapy regimens: all patients enrolled in this study were considered to be inoperable, so received first-line platinum-based chemotherapy (Patients receiving definitive chemoradiotherapy were excluded): cisplatin, or carboplatin, both administered, in combination with navelbine, or gemcitabine, or paclitaxel, or docetaxel. Few patients were given other platinum-based treatment. All chemotherapeutic drugs were administered intravenously, and all included patients were treated for two to six cycles. TGFBR2 SNP selection and genotyping: the genotype data of TGFBR2 gene regionfrom the CHB population were downloaded from phase II HapMap SNP database, and tag-SNPs were selected by the Haploview Software, using a minor allele frequency (MAF) cut-off of 0.05 and r threshold of 0.8. Blood samples were obtained in EDTA tubes from patients at the time of re-cruitment. Genomic DNA was extracted using the QIAamp DNA Maxi Kit. All SNPs selected were genotyped using iSelect HD BeadChip (illumina), with quality control criteria as follows: genotyping call rate of SNP>0.95; MAF>0.05; GenCall score>0.2. Therefore, a polymerase chain reaction (PCR)-SNaPshot method was used to supplement Statistical Analysis. The analyses were specified to investigate the relation-ships between TGFBR2 polymorphisms and severe toxicity occurrence, overall and by treatment arm, respectively. Toxicity outcomes were dichotomized by the presence or absence of (i) any grade 3 or 4 overall toxicity, (ii) any grade 3 or 4 hematologic toxicity (including neutropenia, anemia, and thrombocytopenia), and (iii) any grade 3 or 4 gastrointestinal toxicity (nausea/vomiting). We then investigated whether these polymorphisms were associated with severe hematological toxicity, gastrointestinal toxicity, or disease controlled rate among 1004 platinum-based chemotherapy treated advanced NSCLC patients. Single gene polymorphisms correlation analysis has been done. OR, 95% confidence interval and p value were calculated respectively. Each polymorphic loci (SNP) of the mutant homozygous genotype (BB ) or mutant heterozygous mutant genotype (AB), compared with wild homozygous genotype(AA),is represented by BB VS AA or AB VS AA.Adjusting covariates were the genotyping data of polymorphisms (gender, age at diagnosis, performance status and type of treatment regimen. Statistical analyses used SPSS. Pairwise linkage disequilibrium defined by the four-gamete rule in the Haploview Software. Individual haplotype frequencies were estimated based on the Bayesian algorithm, using the PHASE 2.0 program. Haplotype-toxicity association was evaluated for each block, using SPSS.Outcome:In this study, 33 tag single nucleotide polymorphisms in TGFBR2 gene were selected except rs9844092 (MAF =0). 1004 patients enrolled in the study. Among the 1004 NSCLC patients. The median age of patients was 58 years (range, 18–82), and there were 706 patients (male) and 297 (female). The majority of patients (62.6%) had stage IV disease. Disease controlled rate was 81.7%, while severe toxicity incidenceincidences were 3.1% (anemia), 3.6% ( thrombocytopenia), 15.2% (leukocytopenia), 12.3 %( agranulocytosis), 23.9% (any grade 3 or 4 hematologic toxicity), and 8.3% (any grade 3 or 4 gastrointestinal toxicity). An association between the variant genotypes of and the risk of severe overall toxicity was aslo observered (rs2228048, CT VS CC, OR= 1.638, 95% CI =1.131 - 2.372, p = 0.00894, among male group; rs2276768, CT VS CC, OR = 3.026, 95%CI = 1.741-5.258, p=0.00008575, among female patient groups.An increased risk was assciated between the variatn genotypes (rs9310940, TT VS GG,OR = 4.85,95%CI=1.503-15.65,p=0.00825, among adenocarcinoma Patient groups.Conclusion: this study showed TGFBR2 gene polymorphism played a predictive role on clinic outcome in advanced NSCLC patients receiving first-line platinum-based chemotherapy, especially among female patient groups. Furthermore, was associated with hematological toxicity through mRNA expression.