Interethnic difference in the allelic distribution of human epidermal growth factor receptor intron 1 polymorphism.

PURPOSE: Epidermal growth factor receptor (EGFR) plays a critical role in signal transduction and is a target for a novel class of anticancer agents that aim to inhibit EGFR-mediated cancer cell growth. Previous studies have demonstrated a dinucleotide (CA)(n) repeat polymorphism in intron 1 of EGFR, ranging from 14 to 21 repeats, that has been suggested to regulate EGFR expression. The longer allele with 21 repeats showed an 80% reduction of gene expression compared with the shorter allele with 16 repeats. Therefore, the evaluation of the allelic distribution of this polymorphism in populations of various ethnic origins will be crucial to understand the interindividual variability in EGFR expression. EXPERIMENTAL DESIGN: We evaluated the influence of ethnicity on this polymorphism by genotyping individuals of Caucasian (n = 183), African-American (n = 84), and Asian (n = 66) background. RESULTS: The frequency of one of the longer alleles, allele 20 is significantly higher in Asian individuals (63% compared with 21% in Caucasians, P = 2 x 10(-18)). In confirmation of prior studies, the shorter allele 16 was the most common allele in Caucasians (43%) and African-Americans (42%), but its frequency was significantly lower in Asians (average 17%, P = 10(-7) compared with Caucasians). CONCLUSION: Major interethnic differences in the allelic frequencies of the EGFR intron 1 polymorphism exist. Our results may contribute to a better understanding of the molecular basis underlying ethnic differences in drug response and may be helpful for future strategies of individualized therapy with EGFR inhibitors.     

Gender-related survival differences associated with EGFR polymorphisms in metastatic colon cancer

Evidence is accumulating supporting gender-related differences in the development of colonic carcinomas. Sex steroid hormone receptors are expressed in the colon and interact with epidermal growth factor receptor (EGFR), a gene widely expressed in colonic tissue. Increased EGFR expression is linked with poor prognosis in colon cancer. Within the EGFR gene there are two functional polymorphisms of interest: a polymorphism located at codon 497 (HER-1 R497K) and a dinucleotide (CA)(n) repeat polymorphism located within intron 1. These germ-line polymorphisms of EGFR were analyzed in genomic DNA from 318 metastatic colon cancer patients, 177 males and 141 females, collected from 1992 to 2003. Gender-related survival differences were associated with the HER-1 R497K polymorphism (P(interaction) = 0.003). Females with the HER-1 497 Arg/Arg variant had better overall survival (OS) when compared with the Lys/Lys and/or Lys/Arg variants. In males the opposite was true. The EGFR dinucleotide (CA)(n) repeat also trended with a gender-related OS difference (P(interaction) = 0.11). Females with both short <20 (CA)(n) repeat alleles had better OS than those with any long >or=20 (CA)(n) repeats. In males the opposite was true. Combination analysis of the two polymorphisms taken together also revealed the same gender-related survival difference (P(interaction) = 0.002). These associations were observed using multivariable analysis. The two polymorphisms were not in linkage disequilibrium and are independent of one another. This study supports the role of functional EGFR polymorphisms as independent prognostic markers in metastatic colon cancer. As a prognostic factor, these variants had opposite prognostic implications based on gender.     

Length and loss of heterozygosity of an intron 1 polymorphic sequence of egfr is related to cytogenetic alterations and epithelial growth factor receptor expression

Overexpression of epithelial growth factor receptor (EGFR) is correlated with a poor prognosis and reduced steroid receptor expression. Recently, it was demonstrated that the length of a CA repeat in the intron 1 of EGFR correlated with the expression of EGFR in vitro. We investigated 112 cases of cancerous and noncancerous breast tumor samples for loss of heterozygosity (LOH) in intron 1 of the egfr gene and determined the intratumoral EGFR content and genetic alterations by comparative genomic hybridization. Heterozygous tumors with short CA repeats showed elevated EGFR expression in contrast to tumors with longer CA repeats. Tumors with LOH in intron 1 of egfr revealed higher EGFR expression when the longer allele was lost compared with loss of the shorter allele. Additionally, tumors with a loss of the long allele showed more chromosomal alterations, especially a higher frequency of amplifications. We conclude that the CA repeat status in intron 1 of the egfr gene also modulates the intratumoral EGFR content in vivo. Furthermore, LOH at the CA repeat is associated with genetically advanced tumors. Therefore, allele-specific gene expression due to LOH of the CA repeat could be assumed to be an important event in invasive breast cancer development.     

Epidermal growth factor receptor (EGFR) polymorphisms and survival in head and neck cancer patients

EGFR overexpression has been implicated in the development of head and neck squamous cell carcinoma (HNSCC). This study evaluates the prognostic ability of four polymorphisms in EGFR gene for patients diagnosed with HNSCC and treated with chemoradiation. EGFR polymorphisms in the promoter region were not associated with clinical or pathological characteristics. In relation to R497K polymorphism, patients with the Arg/Arg genotype showed the highest risk of disease-specificity mortality and none of the patients with the Lys/Lys genotype died throughout the follow-up period of the study. Patients with (CA)(n) repeats <17 in both alleles tended toward inferior overall survival compared with those with (CA)(n) repeats > or = 17 in both alleles (p=0.07). Moreover, the distribution of patients with any (CA)(n) repeats > or = 17 and both alleles <17 was statistically different across patients who were recorded as having partial response or no response to therapy (p=0.034). Combination analysis of both polymorphisms, (CA)(n) repeats and R497K, suggests that these polymorphisms may be associated with clinical outcome in patients treated with chemoradiation.     

Functional EGFR germline polymorphisms may confer risk for EGFR somatic mutations in non-small cell lung cancer, with a predominant effect on exon 19 microdeletions

Somatic mutations in the EGFR tyrosine kinase domain play a critical role in the development and treatment of non-small cell lung cancer (NSCLC). Strong genetic influence on susceptibility to these mutations has been suggested. To identify the genetic factors conferring risk for the EGFR tyrosine kinase mutations in NSCLC, a case-control study was conducted in 141 Taiwanese NSCLC patients by focusing on three functional polymorphisms in the EGFR gene [-216G/T, intron 1 (CA)n, and R497K]. Allelic imbalance of the EGFR -216G/T polymorphism was also tested in the heterozygous patients and in the NCI-60 cancer cell lines to further verify its function. We found that the frequencies of the alleles -216T and CA-19 are significantly higher in the patients with any mutation (P = 0.032 and 0.01, respectively), in particular in those with exon 19 microdeletions (P = 0.006 and 0.033, respectively), but not in the patients with L858R mutation. The -216T allele is favored to be amplified in both tumor DNA of lung cancer patients and cancer cell lines. We conclude that the local haplotype structures across the EGFR gene may favor the development of cellular malignancies and thus significantly confer risk to the occurrence of EGFR mutations in NSCLC, particularly the exon 19 microdeletions.     

Evaluation of the epidermal growth factor receptor (EGFR) in colorectal tumours and lymph node metastases

Overexpression of the epidermal growth factor receptor (EGFR) often correlates with an aggressive tumour phenotype and poor prognosis. To examine the relevance of EGFR in colorectal cancer, we determined the expression of EGFR protein in 249 colorectal adenocarcinomas and 42 lymph node metastases using immunohistochemistry. Moreover, we investigated a (CA)(n) dinucleotide repeat polymorphism of the EGFR gene in a subset of 114 tumours. High levels of EGFR protein were observed in 123/249 (49.4%) samples. EGFR expression in colorectal carcinomas correlated with differentiation grade (P=0.014). However, there were no associations with Dukes' stage, site, patient age or gender. EGFR protein expression did not influence survival in this colorectal cancer patient cohort (P>or=0.05). Expression was not identical in paired colorectal tumours and lymph node metastases, with only 17/42 (40.5%) samples showing equivalent EGFR levels (P>0.05). The distribution of the (CA)(n) dinucleotide repeat alleles in colorectal adenocarcinomas was not associated with EGFR protein expression (P>0.05). These results indicate that while EGFR overexpression is a common event in colorectal carcinogenesis, it does not influence patient prognosis.     

CYP1A1*2A polymorphism as a predictor of clinical outcome in advanced lung cancer patients treated with EGFR-TKI and its combined effects with EGFR intron 1 (CA)n polymorphism

Background

Mutations in the epidermal growth factor receptor (EGFR) have been confirmed as predictors of efficacy for EGFR-tyrosine kinase inhibitors (TKIs). We investigated whether polymorphisms of the EGFR and cytochrome P450, family 1, member A1 (CYP1A1) genes were associated with clinical outcome in NSCLC patients treated with EGFR-TKI.

Methods

Genotypes for the intron 1 (CA)n repeat and R497K polymorphisms in the EGFR gene and the *2A (3801 T → C) and *2C (2455 A → G) polymorphisms in CYP1A1 gene were evaluated in 115 NSCLC patients by PCR-RFLP and DNA sequencing. Genetic polymorphisms were correlated with clinical outcomes of EGFR-TKIs. From a subgroup of patients whose tumour tissues were available, associations between somatic EGFR mutations, EGFR expression, and genomic polymorphisms were also analysed.

Results

EGFR intron 1 (CA)n and CYP1A1*2A polymorphisms were independent predictive factors (p = 0.046, p = 0.011, respectively) and the latter was also a prognostic factor (p = 0.001) for patients treated with EGFR-TKIs. We also observed a strong synergistic effect from two genotypes. Specifically, patients with both the T/T allele of the CYP1A1 gene and shorter intron 1 CA repeats (?16 CA) of the EGFR gene showed an improved response (p = 0.002) compared with patients with the T/C or C/C allele and longer intron 1 CA repeats (both alleles >16 CA). In contrast, for R497K and CYP1A1*2C, no relationship was observed with clinical outcome for patients treated with EGFR-TKIs (p = 0.573; p = 0.629, respectively). Both SNPs in the CYP1A1 gene showed a correlation with EGFR somatic mutations.

Conclusions

The findings of this study suggest that the CYP1A1*2A polymorphism is a predictor for clinical outcome in NSCLC patients treated with EGFR-TKI therapy, and combining analysis of both CYP1A1*2A and EGFR intron 1 (CA)n polymorphisms may be useful for predicting treatment outcome in NSCLC patients treated with EGFR-TKIs.     

Epidermal growth factor receptor intron 1 CA dinucleotide repeat polymorphism and survival of advanced gastric cancer patients treated with cetuximab plus modified FOLFOX6

(Cancer Sci 2010; 101: 793–799) Cetuximab is a monoclonal antibody targeting epidermal growth factor receptor (EGFR). The present study investigated the association between germline genetic polymorphisms and the treatment outcome of cetuximab plus modified leucovovin, fluorouracil, and oxaliplatin (FOLFOX)6 chemotherapy in advanced gastric cancer (AGC). DNA from peripheral blood mononuclear cells of 38 patients enrolled in a phase II study of cetuximab plus modified FOLFOX6 were analyzed for 16 polymorphisms in eight genes (EGFR, epidermal growth factor, transforming growth factor‐α (TGFA), thymidylate synthase, excision repair cross‐complementation group 1, Xeroderma pigmentosum group D, and fragment c gamma receptors (FCGR)2A and 3A). The EGFR intron 1 CA repeat polymorphism was associated with survival. Twenty‐one patients had low repeats (sum of both alleles ≤37), and 17 patients had high repeats (sum ≥38). Patients with low CA repeats had longer progression‐free survival (adjusted hazard ratio [HR] 0.42 [95% confidence interval [CI] 0.19–0.96], P = 0.040) and overall survival (adjusted HR 0.40 [95% CI 0.16–0.99], P = 0.048) compared with patients with high CA repeats. In addition, the tumor EGFR expression was higher in patients with a lower number of CA repeats. The association between the CA repeat status and survival was not found in a separate cohort of AGC patients (n = 68) treated only with modified FOLFOX6. These results suggest that the EGFR intron 1 CA repeat polymorphism could be a useful, predictive biomarker of cetuximab efficacy in AGC and merits further investigation in randomized studies.     

Activating mutations in the tyrosine kinase domain of the epidermal growth factor receptor are associated with improved survival in gefitinib-treated chemorefractory lung adenocarcinomas.

PURPOSE: Activating mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) confer a strong sensitivity to gefitinib, a selective tyrosine kinase inhibitor of EGFR. EXPERIMENTAL DESIGN: We examined EGFR mutations at exons 18, 19, and 21 in tumor tissue from 68 gefitinib-treated, chemorefractory, advanced non-small cell lung cancer patients from the United States, Europe, and Asia and in a highly gefitinib-sensitive non-small cell lung cancer cell line and correlated their presence with response and survival. In addition, in a subgroup of 28 patients for whom the remaining tumor tissue was available, we examined the relationship among EGFR mutations, CA repeats in intron 1 of EGFR, EGFR and caveolin-1 mRNA levels, and increased EGFR gene copy numbers. RESULTS: Seventeen patients had EGFR mutations, all of which were in lung adenocarcinomas. Radiographic response was observed in 16 of 17 (94.1%) patients harboring EGFR mutations, in contrast with 6 of 51 (12.6%) with wild-type EGFR (P < 0.0001). Probability of response increased significantly in never smokers, patients receiving a greater number of prior chemotherapy regimens, Asians, and younger patients. Median survival was not reached for patients with EGFR mutations and was 9.9 months for those with wild-type EGFR (P = 0.001). EGFR mutations tended to be associated with increased numbers of CA repeats and increased EGFR gene copy numbers but not with EGFR and caveolin-1 mRNA overexpression (P = not significant). CONCLUSIONS: The presence of EGFR mutations is a major determinant of gefitinib response, and targeting EGFR should be considered in preference to chemotherapy as first-line treatment in lung adenocarcinomas that have demonstrable EGFR mutations.     

Correlation Between EGFR Mutations and Serum TumorMarkers in Lung Adenocarcinoma Patients

Background: Mutations affecting the epidermal growth factor receptor (EGFR) are good predictors ofclinical efficacy of EGFR tyrosine kinase inhibitors (TKI) in patients with non-small cell lung cancer. Serumcarcinoembryonic antigen (CEA) levels are also regarded as predictive for the efficacy of EGFR-TKI andEGFR gene mutations. This study analyzed the association between EGFR gene mutations and clinical features,including serum tumor marker levels in lung adenocarcinomas patients. Patients and Methods: A total of70 lung adenocarcinoma patients with complete clinical data and pathological specimens were investigated.EGFR gene mutations at exons 19 and 21 were assessed. Serum tumor markers were detected by protein chipchemiluminescenceat the corresponding time, and correlations were analyzed. Results: Mutations of the EGFRgene were detected in 27 of the 70 patients and the serum CEA and CA242 concentrations were found to besignificantly associated with the incidence of EGFR gene mutations (P<0.05). The AUCs for CEA and CA242 were0.724 (95% CI: 0.598~0.850, P<0.05) and 0.769 (95% CI: 0.523~0.800, P<0.05) respectively. Conclusions: SerumCEA and CA242 levels are associated with mutations of the EGFR gene in patients with lung adenocarcinomas.     

非小细胞肺癌表皮生长因子受体双向基因测序研究

目的 探讨中国人非小细胞肺癌表皮生长因子受体（EGFR）第18、19、21外显子基因突变状态。方法 32例病理证实的非小细胞肺癌组织标本,通过模板DNA提取、定量和Touchdown PCR扩增EGFR exon18、19、21序列,进行正、负链基因测序分析,并与10例非小细胞肺癌患者血液标本对照。结果 32例非小细胞肺癌组织发现7例共9种突变,即已报道的5例19外显子缺失和未见报道的21exonT〉G（L833V）及A〉T（H835L）杂合性突变,另有2例内含子多态改变。中国人非小细胞肺癌突变率为28．1％（9／32）,肺腺癌突变率为31．6％（6／19）。结论 中国人非小细胞肺癌的EGFR突变率与已报道的亚洲人女性肺腺癌的突变率相似,但存在中国人自身新的突变位点（L833V和H835L）及内含子改变,该突变率与国内易瑞沙治疗非小细胞肺癌有效率基本吻合。     

Survival and prognosis analyses of concurrent PIK3CA mutations in EGFR mutant non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors

In non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation, the prognostic impact of a concurrent Phosphoinositide-3-kinase catalytic alpha polypeptide (PIK3CA) mutation was still unknown. Some studies have shown that EGFR mutant NSCLC patients treated with EGFR tyrosine kinase inhibitors (TKIs) when concurrent PIK3CA mutation have a worse prognosis and shorter survival time. This study conducted a retrospective analysis of NSCLC patients with EGFR mutant or concurrent PIK3CA mutations from January 2015 to October 2019 in the First Affiliated Hospital of Nanchang University. Relative to EGFR alone mutations (Single-Mt), we found that NSCLC patients with EGFR mutations coexisting with PIK3CA mutations (Double-Mt) treated with EGFR-TKIs had a shorter median time to progression (TTP): 7.8 months versus 10.9 months (Double-Mt versus Single-Mt, P = 0.001), and decrease in median overall survival (OS): 20.6 months versus 32.4 months (P < 0.001). The objective response rate (ORR) between Double-Mt and Single-Mt was 36.7% versus 61.9% (P = 0.044), disease control rates (DCR) was 80.1% versus 91.7% (P = 0.179). Obviously, EGFR-TKIs for EGFR mutate NSCLC patients when concurrent PIK3CA mutations have a worse prognosis and shorter survival time.