Evaluation Of The Application Value Of EGFR Mutation-Specific Antibodies In Lung Adenocarcinoma

Backgroud and ObjectiveLung cancer is still the most malignant tumor with the highest mortality and morbidity in China.In 2015,there were about 787,000 new cases of lung cancer in China,and the number of deaths due to lung cancer was about 631,000.Platinum chemotherapy has been the only treatment for advanced non-small cell lung cancer(NSCLC)for decades,resulting in a median overall survival(OS)of only 8 to 10 months.With the widespread use of the epidermal growth factor receptor tyrosine kinase inhibitor(EGFR-TKI),the therapeutic effect of NSCLC patients has a rapid development effect,the total incidence of EGFR mutations in Chinese non-selective NSCLC patients is about 30%.In patients with adenocarcinoma,the overall mutation rate of EGFR is 50%,while in non-smoking adenocarcinoma patients,the total mutation rate of EGFR is 60%-70%.EGFR-TKI inhibits tyrosine phosphorylation and inhibits a series of signaling pathways involved in malignant cell formation,proliferation and apoptosis,thereby inhibiting tumor cell proliferation.EGFR-TKI is currently the standard first-line treatment for non-small cell lung cancer,and EGFR mutation status is an important indicator for predicting the efficacy of EGFR-TKI.There are many methods for detecting EGFR gene mutations,but mainly based on tumor DNA by using sequencing and PCR technology to detect new mutations of unknown type or unknown mutations.The most classical representative method is direct DNA sequencing.The method,which detects all known and unknown mutations,is called the"gold standard"for the detection of epidermal growth factor receptor(EGFR)mutations,but its sensitivity is low,and the number of tumor cells contained in the sample is relatively high.Only mutated genes with more than 30%content can be detected.PCR technology is the most representative of the amplified refractory mutation system(ARMS)PCR(ARMS-PCR),which can only detect specific mutations,but the specimens with low tumor content(5%)still have a higher detection rate.No matter which test method is used,it has high requirements for laboratories and personnel.The emergence of EGFR mutation-specific antibodies(E746_A750del and L858R)in 2009 made it possible to simplify the detection of EGFR mutations.In recent years,the application of mutation-specific antibodies,antibody dilution concentration,detection platform,detection results,etc.are widely studied,and the results of molecular detection of EGFR mutations are also deeply studied,but there are huge difference between sensitivity and sensitivity among different studies.The sensitivity is from 30%to100%,and specificity is about 90%.The relationship between antibody expression level and clinical drug use is different,and the results of different studies are quite different,or even the opposite.Most of the studies on EGFR mutation-specific antibodies are based on surgical resection specimens and tissue microarrays(TMA),and there are few comprehensive studies based on surgically resected specimens,biopsy specimens,and cytological specimens.To further confirm the value of EGFR mutations in patients with NSCLC using EGFR mutation-specific antibodies,and the relationship between the expression levels of EGFR mutation-specific antibodies and clinical drugs,we used ARMS-PCR to detect EGFR mutation status and immunohistochemistry in patients with NSCLC,andto detect the expression level of EGFR mutation-specific antibodies in patients with NSCLC,analyze the consistency of EGFR mutation status and the relationship between EGFR mutation-specific antibody expression and clinical drug by ARMS-PCR and immunohistochemistry,and comprehensively evaluate the application value of EGFR mutation-specific antibodies in NSCLC patients.Material and methods1.ARMS-PCR was used to detect 154 non-small cell lung cancer samples,including 61 surgically resected specimens,75 biopsy specimens,18 pleural fluid sediment paraffin-embedded specimens(cytological specimens),EGFR mutation status and the specificity of two EGFR mutations expression of antibodies E746_A750 and L858R.2.Data analysis was performed using the SPSS21.0 software package.The comparison of the count data was performed by the x 2 test or the Fisher exact probability method.Univariate and multivariate cox regression analysis were used to quantify the relationship between mutation-specific antibodies and clinical prognosis in patients with NSCLC.The difference was significant at p<0.05.Result1.ARMS-PCR detection of EGFR19 exon deletion mutation and L858R mutation in surgical resection specimens,biopsy specimens,cytological specimen's mutation rate were 44.3%,41.0%,48.0%,41.3%,38.9%,27.8%.There was no significant difference in three type of test results(P>0.05).2.When?1+was used as the positive standard,the specificity and sensitivity of E746_A750 mutant antibody were 55.6%,97.1%,61.1%,94.9%,and 42.9%,100.0%in the diagnosis of EGFR gene exon deletion mutation in surgically resected specimens,biopsy specimens and cytological specimens.The difference among three tissue types was not statistically significant(P>0.05).The specificity and sensitivity of L858R mutant antibody were 72.0%,100.0%,67.7%,97.7%,40.0%,100.0%in the diagnosis of EGFR gene exon 21 L858R mutation in surgically resected specimens,biopsy specimens and cytological specimens.There was no significant difference in tissue types(P>0.05).3.When?2+was used as the positive standard,the specificity and sensitivity of E746_A750 mutant antibody were 29.6%,100.0%,38.9%and 97.4%,42.9%,100.0%in the diagnosis of EGFR gene exon deletion mutation in surgically excised specimens,biopsy specimens and cytological specimens.the difference among the three tissue types was not statistically significant(P>0.05).The specificity and sensitivity of L858R mutant antibody were 44.0%,100.0%,38.7%,100.0%,and 0.0%,100.0%in the diagnosis of EGFR gene exon 21 L858R mutation in surgically resected specimens,biopsy specimens and cytological specimens.There was no significant difference in tissue types(P>0.05).4.When 3+was used as the positive standard,the specificity and sensitivity of E746_A750 mutant antibody were 14.8%,100.0%,22.2%and 100.0%,14.3%,100.0%in the diagnosis of EGFR gene exon deletion mutation in surgically excised specimens,biopsy specimens and cytological specimens.The differences among the three tissue types was not statistically significant(P>0.05).The specificity and sensitivity of L858R mutant antibody were 20.0%,100.0%,22.6%,100.0%,0.0%,100.0%in the diagnosis of EGFR gene exon 21 L858R mutation in surgically resected specimens,biopsy specimens and cytological specimens.There was no significant difference in tissue types(P<0.05).5.The expression level of E746_A750 mutant antibody was not related to gender,age,smoking,tumour size,lymph node metastasis,or pleural invasion(P>0.05).The antibody was expressed in lung adenocarcinoma with acinar or adherent histology,and was hardly expressed in histological lung adenocarcinoma with papillary,micropapillary and solid body.The difference was statistically significant(P<0.05).6.The expression level of L858R mutant antibody was not related to gender,age,smoking,tumour size,lymph node metastasis,or pleural invasion(P>0.05).The antibody was expressed in lung adenocarcinoma with acinar or adherent histology,and was hardly expressed in histological lung adenocarcinoma with papillary,micropapillary and solid body.The difference was statistically significant(P<0.05).7.The difference in median PFS and OS with gefitinib was independent of gender,age,smoking,tumour size,distant metastasis,and expression of mutation-specific antibodies(P>0.05).Conclusion1.EGFR mutation-specific antibodies are not associated with gender,age,smoking,or TNM staging of NSCLC patients,are related to the histological type of the tumour,are highly expressed in acinar or adherent types,and lowly expressed in papillary,micropapillary,solid tumours.2.When the immunohistochemical results define 3+as positive,the consistency with the molecular detection of EGFR mutation results is 100%,which can be used as a rapid and inexpensive EGFR mutation screening index.3.The expression level of EGFR mutation-specific antibodies was not associated with median PFS and OS after administration of gefitinib.