• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4279-4282
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• 2013

Background: The activation and inactivation of receptor tyrosine kinases are tightly regulated to ensure faithful replication of cells. After having transduced extracellular growth activating signals, activated EGFR is subjected to downregulation either by clathrin mediated endocytosis or c-Cbl mediated proteasome degradation depending on the ligand concentration. c-Cbl is an ubiquitin ligase which requires a phosphorylated tyrosine residue at position 1045 in the cytoplasmic domain of EGFR to interact and add ubiquitin molecules. While activating mutations in exons 19 and 21 have been associated with the development of several cancers, the status of mutations at tyrosine 1045 coding exon 27 of EGFR remain to be investigated. Consistently, defective phosphorylation at 1045 has been associated with sustained phosphorylation of EGFR in non-small lung carcinomas. Hence in the present study we investigated the genetic status of the tyrosine 1045 coding site within exon 27 of EGFR gene to explore for possible occurrence of mutations in this region, especially since no studies have addressed this issue so far. Materials and Methods: Tumor chromosomal DNA isolated from thirty five surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking the tyrosine 1045 coding exon 27 of EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status. Results: Sequence analysis identified no mutations in the tyrosine 1045 codon of EGFR in any of the thirty five samples that were analyzed. Conclusions: The lack of identification of mutation in the tyrosine 1045 codon of EGFR suggests that mutations in this region may be relatively rare in oral squamous cell carcinomas. To the best of our knowledge, this study is the first to have explored the genetic status of exon 27 of EGFR in oral squamous cell carcinoma tissue samples.

• Asian Pacific Journal of Cancer Prevention
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• 제16권11호
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• pp.4759-4768
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• 2015

Background: Several studies have investigated predictive and prognostic biomarkers for patients treated with anti-epidermal growth factor receptor (EGFR) agents in lung cancer. However, the conclusion is controversial. Materials and Methods: A meta-analysis was conducted to evaluate the associations of mutant K-ras, PIK3CA and PTEN deficiency with the efficacy of anti-EGFR agents in lung cancer. The primary endpoint was objective response rate (ORR). The secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results: A total of 61 studies were included in the final meta-analysis. The result showed that K-ras mutation was a good predictor for ORR (RR=0.42, 95%CI, 0.33-0.55, p=0.000) and an effective prognostic marker for OS (HR=1.37, 95%CI, 1.15-1.65, p=0.001) and PFS (HR=1.33, 95%CI, 1.05-1.69, p=0.019). However, PTEN deficiency or PIK3CA mutation did not show any significance predictive value for ORR (PTEN, RR=0.82, 95%CI, 0.56-1.19, p=0.286; PIK3CA, RR=1.08, 95%CI, 0.17-6.66, P=0.938). And PTEN deficiency or expression of PIK3CA did not show significance prognostic value for OS (PTEN, HR=0.88, 95%CI, 0.31-2.46,P=0.805; PIK3CA, HR=0.79, 95%CI: 0.23-2.68, P=0.706). Conclusions: Our meta-analysis showed that K-ras mutation may be an effective predictor in lung cancer patients treated with anti-EGFR agents. Whereas, the predictive and prognostic value of PTEN deficiency and PIK3CA mutation need to be further investigated.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5599-5603
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• 2012

Background: The epidermal growth factor receptor (EGFR) is a potential therapeutic target for breast cancer treatment; however, its use does not lead to a marked clinical response. Studies of non-small cell lung cancer and colorectal cancer showed that mutations of genes in the PIK3CA/AKT and RAS/RAF/MEK pathways, two major signalling cascades downstream of EGFR, might predict resistance to EGFR-targeted agents. Therefore, we examined the frequencies of mutations in these key EGFR pathway genes in Chinese breast cancer patients. Methods: We used a high-throughput mass-spectrometric based cancer gene mutation profiling platform to detect 22 mutations of the PIK3CA, AKT1, BRAF, EGFR, HRAS, and KRAS genes in 120 Chinese women with breast cancer. Results: Thirteen mutations were detected in 12 (10%) of the samples, all of which were invasive ductal carcinomas (two stage I, six stage II, three stage III, and one stage IV). These included one mutation (0.83%) in the EGFR gene (rs121913445-rs121913432), three (2.50%) in the KRAS gene (rs121913530, rs112445441), and nine (7.50%) in the PIK3CA gene (rs121913273, rs104886003, and rs121913279). No mutations were found in the AKT1, BRAF, and HRAS genes. Six (27.27%) of the 22 genotyping assays called mutations in at least one sample and three (50%) of the six assays queried were found to be mutated more than once. Conclusions: Mutations in the EGFR pathway occurred in a small fraction of Chinese breast cancers. However, therapeutics targeting these potential predictive markers should be investigated in depth, especially in Oriental populations.

• Asian Pacific Journal of Cancer Prevention
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• 제17권7호
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• pp.3249-3253
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• 2016

Background: Pemetrexed monotherapy has come to be recognized as one of the standard second-line therapies for advanced non-squamous non-small cell lung cancer (NSCLC). However, there have been no reports of studies that have evaluated the efficacy of pemetrexed according to type of active EGFR mutation, i.e., an exon 19 deletion or an L858R point mutation. Materials and Methods: The records of non-squamous NSCLC patients harboring an EGFR mutation who received pemetrexed monotherapy as a second or later line of chemotherapy at Kitasato University Hospital between March 2010 and October 2015 were retrospectively reviewed, and the treatment outcomes were evaluated. Results: The overall response rate and progression-free survival time (PFS) of the 53 patients with non-squamous NSCLC were 15.1% and 2.3 months, respectively. There were significant differences between the disease control rate (37.5% vs. 76.2%) and PFS time (1.8 months vs. 3.3 months) of the exon 19 deletion group and the L858R point mutation group, and a multivariate analysis identified type of EGFR mutation as well as performance status (PS) as independent predictors of PFS. Conclusions: The clinical data obtained in this study provided a valuable rationale for considering type of EGFR mutation as well as non-squamous histology as predictors of the efficacy of pemetrexed monotherapy.

• Tuberculosis and Respiratory Diseases
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• 제73권6호
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• pp.303-311
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• 2012

Background: This study was designed to analyze the efficacy of gefitinib as a second-line therapy, according to the clinical characteristics in Korean patients with non-small-cell lung cancer (NSCLC). Methods: In this Phase IV observational study, we recruited patients, previously failed first-line chemotherapy, who had locally advanced or metastatic NSCLC, and who were found to be either epidermal growth factor receptor (EGFR) mutation-positive or satisfied 2 or more of the 3 characteristics: adenocarcinoma, female, and non-smoker. These patients were administered with gefitinib 250 mg/day, orally. The primary endpoints were to evaluate the objective response rate (ORR) and to determine the relationship of ORRs, depending on each patient's characteristics of modified intent-to-treat population. Results: A total of 138 patients participated in this study. One subject achieved complete response, and 42 subjects achieved partial response (ORR, 31.2%). The subgroup analysis demonstrated that the ORR was significantly higher in patients with EGFR mutation-positive, compared to that of EGFR mutation-negative (45.8% vs. 14.0%, p=0.0004). In a secondary efficacy variable, the median progression-free survival (PFS) was 5.7 months (95% confidence interval, 3.9~8.4 months) and the 6-month PFS and overall survival were 49.6% and 87.9%, respectively. The most common reported adverse events were rash (34.4%), diarrhea (26.6%), pruritus (17.5%), and cough (15.6%). Conclusion: Gefitinib was observed in anti-tumor activity with favorable tolerability profile as a second-line therapy in these selected patients. When looking at EGFR mutation status, EGFR mutation-positive showed strong association with gefitinib by greater response and prolonged PFS, compared with that of EGFR mutation-negative.

• Tuberculosis and Respiratory Diseases
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• 제80권2호
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• pp.187-193
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• 2017

Background: Third-generation tyrosine kinase inhibitors of the epidermal growth factor receptor (EGFR-TKIs) have proved efficacious in treating non-small cell lung cancer (NSCLC) patients with acquired resistance resulting from the T790M mutation. However, since almost 50% patients with the acquired resistance do not harbor the T790M mutation, retreatment with first- or second-generation EGFR-TKIs may be a more viable therapeutic option. Here, we identified positive response predictors to retreatment, in patients who switched to a different EGFR-TKI, following initial treatment failure. Methods: This study retrospectively reviewed the medical records of 42 NSCLC patients with EGFR mutations, whose cancers had progressed following initial treatment with gefitinib or erlotinib, and who had switched to a different first-generation EGFR-TKI during subsequent retreatment. To identify high response rate predictors in the changed EGFR-TKI retreatment, we analyzed the relationship between clinical and demographic parameters, and positive clinical outcomes, following retreatment with EGFR-TKI. Results: Overall, 30 (71.4%) patients received gefitinib and 12 (28.6%) patients received erlotinib as their first EGFR-TKI treatment. Following retreatment with a different EGFR-TKI, the overall response and disease control rates were 21.4% and 64.3%, respectively. There was no significant association between their overall responses. The median progression-free survival (PFS) after retreatment was 2.0 months. However, PFS was significantly longer in patients whose time to progression was ${\geq}10months$ following initial EGFR-TKI treatment, who had a mutation of exon 19, or whose treatment interval was <90 days. Conclusion: In patients with acquired resistance to initial EGFR-TKI therapy, switched EGFR-TKI retreatment may be a salvage therapy for individuals possessing positive retreatment response predictors.

• 분석과학
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• 제22권6호
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• pp.498-503
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• 2009

폐암은 전 세계적으로 높은 사망률 때문에 죽음에 이르게 되는 암이다. 폐암은 소세포암과 비소 세포암 두 종류로 나누어 지는데 비소세포암 환자에게서 EGFR 돌연변이가 발견되었고 이 EGFR 돌연변이는 방사선치료와 EGFR tyrosin kinase의 저해제인 gefitinib과 erlotinib의 반응에도 연관되어진다. 이와 같이 EGFR 돌연변이의 검출은 효과적인 치료방법을 제시해 줄 수 있을 것이다. 본 연구에서는 간단하고 값이 싸며, 반응시간이 더 빠르게 유전자 다형성을 검출 할 수 있는 칩-기반 등온증폭반응을 수행하였다. 그 결과, 이 등온증폭 방법은 빠른 증폭 시간과 높은 민감성, 특이성을 가지고 있었으며 현증 검증에서 EGFR 돌연변이를 빠르고 정확하게 진단할 수 있는 유용한 방법이 될 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권17호
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• pp.7125-7128
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• 2014

Background: Acquired genetic alterations and presence of sensitizing mutations in the tyrosine kinase domain of EGFR and other signaling molecules have been found in different subsets of primary lung adenocarcinoma. The commonest EGFR mutations are small in frame deletions of exon 19 and a point mutation (L858R) in exon 21, having a combined occurrence of around 90%. The objective of this study was to determine the frequency and types of EGFR mutations in primary lung adenocarcinomas in Pakistan. Materials and Methods: EGFR mutations in tumor samples were screened by multiplex real time PCR. Briefly, DNA from formalin fixed paraffin-embedded tissue was amplified with primers and probes specific to 43 different EGFR mutations in a Cobas z 480 instrument. The assay detects mutations in four exons (18-21) of the EGFR gene. Results: Out of 94 patients, 65 were males and 29 females with a M:F ratio of 2.2: 1. The median age was 62 years (range, 28 - 85 years). In our biopsy samples 70 (74%) cases were of primary lung adenocarcinoma, whereas 24 (26%) were confirmed metastatic adenocarcinoma of primary lung origin. EGFR mutation was positive in 29% of the patients. The highest frequency of L858R was observed in 48% of these, followed by deletion in exon 19 (44%). In addition, other rare mutations such as compound G718X:S768I and insertions in exon 20 insertion were detected in approximately 4% of the patients. Conclusions: This study showed that Del 19 and L858R are the most frequent mutations in Pakistani lung adenocarcinoma patients and around 29% of the patients were found eligible for erlotinib therapy.

• Asian Pacific Journal of Cancer Prevention
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• 제15권1호
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• pp.321-326
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• 2014

Background: Mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) are predictive of response to EGFR-targeted therapy in advanced stages of disease. This study aimed to determine the frequency of EGFR mutations in NSCLCs and to correlate their presence with clinical characteristics in multiethnic Malaysian patients. Materials and Methods: In this prospective study, EGFR mutations in exons 18, 19, 20 and 21 in formalin-fixed paraffin-embedded biopsy specimens of consecutive NSCLC patients were asessed by real-time polymerase chain reaction. Results: EGFR mutations were detected in NSCLCs from 55 (36.4%) of a total of 151 patients, being significantly more common in females (62.5%) than in males (17.2%) [odds ratio (OR), 8.00; 95% confidence interval (CI), 3.77-16.98; p<0.001] and in never smokers (62.5%) than in ever smokers (12.7%) (OR, 11.50; 95%CI, 5.08-26.03; p<0.001). Mutations were more common in adenocarcinoma (39.4%) compared to non-adenocarcinoma NSCLCs (15.8%) (p=0.072). The mutation rates in patients of different ethnicities were not significantly different (p=0.08). Never smoking status was the only clinical feature that independently predicted the presence of EGFR mutations (adjusted OR, 5.94; 95%CI, 1.94-18.17; p=0.002). Conclusions: In Malaysian patients with NSCLC, the EGFR mutation rate was similar to that in other Asian populations. EGFR mutations were significantly more common in female patients and in never smokers. Never smoking status was the only independent predictor for the presence of EGFR mutations.

• Tuberculosis and Respiratory Diseases
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• 제70권1호
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• pp.21-27
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• 2011

Background: Although the gold standard method for research trials on epidermal growth factor receptor (EGFR) mutations has been direct sequencing, this approach has the limitations of low sensitivity and of being time-consuming. Peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping is known to be a more sensitive detection tool. The aim of this study was to compare the detection rate of $EGFR$ mutation and EGFR-tyrosine kinase inhibitor (TKI) responsiveness according to $EGFR$ mutation status using both methodologies. Methods: Clinical specimens from 112 NSCLC patients were analyzed for $EGFR$ mutations in exons 18, 19, 20, and 21. All clinical data and tumor specimens were obtained from 3 university hospitals in Korea. After genomic DNA was extracted from paraffin-embedded tissue specimens, both PNA-mediated PCR clamping and direct-sequencing were performed. The results and clinical response to $EGFR$-TKIs were compared. Results: Sequencing revealed a total of 35 (22.9%) mutations: 8 missense mutations in exon 21 and 26 deletion mutations in exon 19. PNA-mediated PCR clamping showed the presence of genomic alterations in 45 (28.3%) samples, including the 32 identified by sequencing plus 13 additional samples (6 in exon 19 and 7 in exon 21). Conclusion: PNA-mediated PCR clamping is simple and rapid, as well as a more sensitive method for screening of genomic alterations in $EGFR$ gene compared to direct sequencing. This data suggests that PNA-mediated PCR clamping should be implemented as a useful screening tool for detection of $EGFR$ mutations in clinical setting.