Differences in utilization of ALK rearrangement FISH analysis and EGFR assay.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e18067-e18067
Author(s):  
Christopher S. Lathan ◽  
Julie Ann Lynch
Keyword(s):  
Incidence Rate ◽  
Diagnostic Test ◽  
Egfr Mutation ◽  
Penetration Rate ◽  
Egfr Mutations ◽  
Fish Analysis ◽  
Alk Rearrangement ◽  
Regional Factors ◽  
Public Datasets ◽  
Nsclc Patients

e18067 Background: This study examined institutional and regional factors associated with use of ALK rearrangement FISH diagnostic test compared to the EGFR assay. Previous research presented at AACR Cancer Disparities conference illustrated substantial underutilization of the EGFR assay. Disparities existed in access by institutional and regional factors. Methods: We linked proprietary industry data for clinical diagnostic assays (EGFR mutation and ALK rearrangement) provided by Genzyme Genetics and Abbott Molecular to public datasets which provided institutional and regional characteristics of US hospitals. Individual orders were aggregated and summarized to the hospital. Each hospital’s Medicare provider number (known as the OSCAR number) was obtained and recorded. OSCAR number and zip code were used to link the proprietary and public datasets. Public datasets included Census files, CMS/NCI Provider of Service (POS) files, among others, all current as of 2011. Logistic and multiple regression analysis were conducted. Results: Initial analysis of data suggests higher utilization of the ALK rearrangement FISH analysis when compared to EGFR Assay. However, even with incorporation of both assays into clinical practice guidelines, significant institutional and regional differences existed in access to tumor tissue analysis. 7800 EGFR assay tests were sold in 2010. First 5 months post approval; approximately 12,000 Vysis tests were sold. A reasonable approximation of the testable population of NSCLC patients, given histology and tissue availability is approximately 114,000 patients. This suggests a 7% penetration rate for the EGFR mutation analysis and a 10% penetration rate for ALK rearrangement assay, though EGFR mutations have a 15% incidence rate compared to 5% incidence rate of EML-ALK4 rearrangement. Conclusions: Uptake of the ALK rearrangement assay is likely higher due to the linkage of crizotinib to the FISH diagnostic test. Utilization patterns show regional underutilization that could contribute to disparities.

Usefulness of cytological samples (CS) for the assessment of ALK rearrangements in non-small cell lung cancer (NSCLC).

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e18008-e18008 ◽  
Author(s):  
Maria D. Lozano ◽  
Tania Labiano ◽  
Maria I. Zudaire ◽  
Alfonso Gurpide ◽  
Javier Zulueta ◽  
...  
Keyword(s):  
Molecular Subtype ◽  
Egfr Mutations ◽  
Fish Analysis ◽  
Gene Rearrangements ◽  
Cell Block ◽  
Alk Rearrangement ◽  
Kras Mutations ◽  
Inhibitor Analysis ◽  
Dual Colour ◽  
Nsclc Patients

e18008 Background: ALK gene rearrangements define a new molecular subtype of NSCLC with response to Crizotinib, a dual MET and ALK inhibitor. Analysis of ALK rearrangements has been performed in biopsies or surgical specimens. However, advanced NSCLC is often diagnosed by FNA cytology obtained through minimally invasive techniques, and frequently CS are the only tumour sample available. We assessed the feasibility of determining ALK rearrangements in CS. Methods: We studied prospectively ALK rearrangements in 53 CS from 53 NSCLC patients (30 M/23 F) by FISH (Vysis dual colour break apart probe). We considered positive for ALK rearrangement when > 15% of cells show splits signals. Tumor samples were obtained by bronchoscopy -FNA in 26 cases (49.1%), EBUS-FNA in 7 (13.2%), EUS-FNA in 3 cases (5.7%), CT-FNA in 3 (5.7%), and direct FNA in 6 cases (11.3%). Two cavity fluids (3.8%), 4 imprints (7.5%), and 2 cellblocks received for consultation (3.8%) were also studied. FISH was performed on non-stained ThinPrep in 28 cases (52.8%), Papanicolau stained smears in 15 cases (28.3%), cell block in 9 cases (17%), and 1 stained ThinPrep. All cases were tested for EGFR and KRAS mutations. Correlation cytological/paraffin embedded samples was performed in 4 paired cases. Results: Thirty-seven samples(69.8%) were adequate for FISH analysis. Three cases (8.1%) had ALK rearrangements: non-smoker women with adenocarcinoma, two of them with signet ring cells. One case had a concurrent EGFR mutation in exon 21. FISH study was unsuccessful in 16 cases (30.2%):10 Papanicolau stained smears (62.5%), 5 unstained ThinPrep (31.3%), and 1 cell block. Nineteen ThinPrep slides were adequate for FISH analysis (86.4%) as well as 8 out of 9 cell blocks. Concordance rate in paired cases were 100%. Conclusions: Determination of ALK gene rearrangements in CS is feasible. It is mandatory an exquisite management and care of the samples to preserve quality. ThinPrep and cell blocks are the most suitable samples for FISH analysis, while Papanicolau stained smears provide poor results. Coexistence of ALK gene rearrangements and EGFR mutations was observed in one case, indicating that such alterations are not necessarily mutually exclusive.

Association of EGFR mutation or ALK rearrangement with expression of DNA repair and synthesis genes in never-smoker females with pulmonary adenocarcinoma.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 10527-10527
Author(s):  
Xiaoxia Chen ◽  
Shengxiang Ren ◽  
Peng Kuang ◽  
ChunXia Su ◽  
Jiayu Li ◽  
...  
Keyword(s):  
Dna Repair ◽  
Mrna Expression ◽  
Egfr Mutation ◽  
Excision Repair ◽  
Egfr Mutations ◽  
Mrna Levels ◽  
Alk Rearrangement ◽  
Anaplastic Lymphoma ◽  
Alk Positive ◽  
Nsclc Patients

10527 Background: Epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement was found not only predict the efficacy of targeted drugs, but also associate with the efficacy of chemotherapy drugs in non-small cell lung cancer (NSCLC) patients. We investigated the relationship of EGFR mutation status or ALK rearrangement and DNA repair or synthesis genes, such as excision repair cross-complementing 1 (ERCC1), ribonucleotide reductase subunit M1 (RRM1), thymidylate synthetase (TS) and breast cancer gene one (BRCA1) gene expression, as a potential explanation for these observations. Methods: In this surgical series, 104 resected lung adenocarcinomas from nonsmoker females were analyzed concurrently for the EGFR mutation, ALK rearrangement status and mRNA expression of ERCC1, RRM1, TS and BRCA1 genes. EGFR mutation detection was performed by the method of ADx-ARMS, ALK rearrangement was detected by PCR and the mRNA expression of different genes were tested using the method of real-time PCR. Results: 73 (70.2%) patients harbored EGFR mutations and 10 (9.6%) had ALK rearrangement. The ERCC1 mRNA level in patients with EGFR mutation was 3.44±1.94×10-3 , which is significantly lower than in the patients with ALK positive and both negative(4.60±1.95×10-3 and 4.95±2.33×10-3 respectively, P=0.010). While the TS mRNA levels were significantly lower in the patients with EGFR mutation(1.15±1.38×10-3 VS 2.69±3.97×10-3, P=0.006) or ALK positive (1.21±0.78×10-3VS 2.69±3.97×10-3, P=0.020) than in patients with both negative. Conclusions: NSCLC specimens harboring activating EGFR mutations are more likely to express low ERCC1 and TS mRNA levels, while NSCLC patients with ALK rearrangement are more likely to express low TS mRNA levels, which could be helpful to select a proper chemotherapy regimen for NSCLC patients with known EGFR mutation or ALK fusion status.

Two different patterns of lung adenocarcinoma with concomitant EGFR mutation and ALK rearrangement

2021 ◽  
pp. 030089162110055
Author(s):  
Dashi Zhao ◽  
Jun Fan ◽  
Li Peng ◽  
Bo Huang ◽  
Yili Zhu ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Egfr Mutation ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Alk Rearrangement ◽  
Molecular Alterations ◽  
Anaplastic Lymphoma ◽  
Sporadic Cases ◽  
Epidermal Growth ◽  
Rare Group

Epidermal growth factor receptor ( EGFR) mutations and anaplastic lymphoma kinase ( ALK) rearrangements are considered mutually exclusive in non-small cell lung cancer (NSCLC), especially in lung adenocarcinoma (LUAC). However, sporadic cases harboring concomitant EGFR and ALK alterations have been increasingly reported. There is no consensus opinion regarding the treatment of patients positive for both molecular alterations. NSCLC with EGFR/ ALK coalterations should be separated into two subtypes: unifocal and multifocal LUAC. Here, we present an overview of the available literature regarding this rare group of patients to provide useful suggestions for therapeutic strategies.

EGFR mutations and the correlation with gefitinib therapy in Chinese NSCLC—A systematic review based on individual patient data from 5 medical centers in China

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 7187-7187 ◽  
Author(s):  
Y. Wu ◽  
W. Zhong ◽  
L. Li ◽  
L. Zhang ◽  
C. Zhou ◽  
...  
Keyword(s):  
Mutation Rate ◽  
Egfr Mutation ◽  
Meta Analysis ◽  
Univariate Analysis ◽  
Correlation Factor ◽  
Chinese Patients ◽  
Egfr Mutations ◽  
Medical Centers ◽  
Nsclc Patients ◽  
Wild Group

7187 Background: EGFR mutations were found to have a significant association with response to gefitinib. To date, information on status of EGFR mutation in Chinese remains scanty. Comprehensive review of existing information on EGFR mutations is essential for treatment selection in Chinese patients with advanced NSCLC. Methods: We published 4 abstracts on EGFR mutation in Chinese patients at the 41st ASCO. We performed an IPD-meta-analysis on the data from the above investigators plus another one. The original individual EGFR mutations (exon 18,19,21) data was collected. Gefitinib was given with 250 mg/d until disease progression. Results: Total 407 cases were into the IPD review. The patient characteristic was male: female = 258:149; adenocarcinoma: other = 259:148; smoker: nonsmoker =178:153. The EGFR mutation rate was 3.05% (124/407). For adeno subgroup the EGFR mutation rate was 42.5% (110/259), non- adeno was 9.5% (14/148). In female the EGFR mutation rate was 41.6% (62/149), male was 24.0% (62/258). Non-smoker was 39.2% (60/153), smoker was 18.5% (33/178). In univariate analysis adeno, smoking, gender was significant predictive factors for EGFR mutation but in logistic regression only adeno is independent correlation factor (p = 0.000, 95% CI 2.078—9.001). Conclusions: The EGFR mutation is more common in no-smoking female adeno patients with NSCLC. The EGFR mutation group has a tendency of response rate to gefitinib compare to the EGFR wild group in NSCLC patients. [Table: see text] No significant financial relationships to disclose.

EGFR mutation analysis from REASON: A registry for the epidemiologic and scientific evaluation of EGFR mutation status in newly diagnosed NSCLC patients stage IIIB/IV.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e18016-e18016 ◽  
Author(s):  
Wolfgang Schuette ◽  
Wilfried Ernst Erich Eberhardt ◽  
J.-Mathias Graf von der Schulenburg ◽  
Manfred Dietel ◽  
Peter Schirmacher ◽  
...  
Keyword(s):  
Egfr Mutation ◽  
Smoking Status ◽  
Epidemiological Data ◽  
Standard Test ◽  
Test Method ◽  
Stage Iiib ◽  
Egfr Mutations ◽  
Newly Diagnosed ◽  
Never Smokers ◽  
Nsclc Patients

e18016^ Background: Somatic mutations in the EGFR gene predict for sensitivity to EGFR TKI in patients with adv. NSCLC, yet limited data exists on EGFR mutation rates of all 4 exons in all NSCLC histologies. Methods: The REASON study (NCT00997230) aims to generate data on EGFR mutation (M) status, association of EGFR-M status with clinico-pathological parameters, treatment decisions and clinical outcomes for EGFR M+ patients from a large sample of stage IIIB/IV NSCLC patients in Germany. 4279 subjects for whom EGFR M testing was planned were enrolled at 151 sites (85% hospital based) in Germany. Standard test method was Sanger sequencing. While analysis of exons 19 and 21 was obligatory, exons 18 and 20 were not routinely done at all labs. Primary objectives are epidemiological data on EGFR M status and correlation with clinico-pathological features. Secondary aims are clinical outcome of all EGFR M+ patients (PFS, OS, DCR), clinical management and pharmaco-economic data associated with diagnosis and treatment of EGFR M+ patients. Results: A 2nd interim analysis provided baseline data on 3973 patients. 63% were male; 82% ever-smokers, 18% never-smokers. Adenocarcinoma is most frequent (69%), followed by squamous epithelial carcinoma (19%). 379 patients had EGFR mutations (9.9%) with 9.5% predicting TKI sensitivity and 0.4% resistance. Most common were exon 19 deletions (50%; with 35% DelE746-A750) followed by exon 21 mutations (36.8%; with 72% L858R). Multivariate analysis revealed association of gender, smoking status and histological subtype with EGFR M status (Table). 50% of M+ patients received 1st line TKI vs. 48% doublet CTX. Conclusions: REASON provides the largest data base yet on EGFR M status in Caucasian patients with newly diagnosed stage IIIB/IV NSCLC. Smoking followed by adeno-carcinoma was the strongest predictive factor for EGFR M. Only 50% of EGFR M+ patients received 1st line TKI. [Table: see text]

EGFR-TKI benefit for NSCLC patients with EML4-ALK rearrangement.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e18035-e18035
Author(s):  
Zhijie Wang ◽  
Jie Wang ◽  
Yi Long Wu ◽  
Hua Bai ◽  
Xu-Chao Zhang ◽  
...  
Keyword(s):  
Molecular Subtype ◽  
Objective Response ◽  
Stage Iv ◽  
Progression Free Survival ◽  
Egfr Mutations ◽  
Alk Rearrangement ◽  
Mutant Type ◽  
Egfr Mutant ◽  
Nsclc Patients ◽  
Egfr Tki

e18035 Background: EML4-ALK rearrangement defines a new molecular subtype of non-small-cell lung cancer (NSCLC). To identify the biological profiles of these patients, we examined the clinico-pathologic characteristics and treatment outcomes of NSCLC patients based on EML4-ALK and EGFR mutations. Methods: Patients with stage IV NSCLC were screened for EML4-ALK rearrangement and EGFR mutations at Peking University Cancer Hospital. EML4-ALK was identified using fluorescent in situ hybridization (FISH) confirmed by immunohistochemistry (IHC), and EGFR mutations were determined using denaturing high-performance liquid chromatography (DHPLC). Results: Of the 151 patients screened, 113 had complete follow-up data as an analysis set. The incidence of EML4-ALK was 9.7% (11/113) using FISH, in which 10 cases had sufficient specimens for IHC confirmation and all were positive. Overall, EML4-ALK and EGFR mutations were largely mutually exclusive (p = 0.033), although two patients harbored concurrent mutations. EML4-ALK rearrangement was associated with resistance to EGFR-TKIs compared with the EGFR mutant type and WT/Nonrearrangement type (p = 0.001 for objective response rate; p = 0.004 for disease control rate; p = 0.021 for progression-free survival [PFS]). In terms of patients who received platinum-based doublet chemotherapy, no significant differences were observed in PFS between the EML4-ALK type, EGFR mutant type, and WT/Nonrearrangement type. Moreover, two patients with concurrent EML4-ALK and EGFR mutations had superior PFS after EGFR-TKI compared with single EML4-ALK-rearranged patients. Conclusions: This study presents several biological features of EML4-ALK NSCLC. It is largely mutually exclusive to EGFR mutations, resistant to EGFR-TKI. Coexistence of ALK rearrangement and EGFR mutation in patients with advanced NSCLC might represent a separate genotype with unique biological characteristics.

Epidemiology of PD-L1 and ALK expression and EGFR mutational status in Argentinian patients with lung cancer.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e20565-e20565 ◽  
Author(s):  
Ruben Salanova ◽  
Julio C Calderazzo Pereyra ◽  
Laura Leguina ◽  
Asuncion Bena ◽  
Mariana Barberis ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Patients ◽  
Egfr Mutation ◽  
Egfr Mutations ◽  
Alk Rearrangement ◽  
Lung Cancer Patients ◽  
Mutational Status ◽  
Alk Positive ◽  
Egfr Mutant ◽  
Exon 19

e20565 Background: Until now, the results of the correlation between PD-L1, ALK expression and EGFR mutations remain controversial. We prospectively evaluated patterns among EGFR mutant, ALK positive and PD-L1 positive lung cancer patients. Methods: PD-L1 and ALK expression was evaluated in 342 adenocarcinomas (AD) of the lung using inmunohistochemestry (anti-PD-L1 22C3, anti-ALK D5F3), and EGFR mutations using real time PCR (therascreen EGFR RGQ PCR Kit version 2). PD-L1 was also evaluated in 36 squamous (SQ) cell carcinomas. Results: 181 of 342 patients with AD were positive for PD-L1. 108 were positive with a TPS value between 1 and 49, and 73 were positive with a TPS value higher than 50 (p = 0.002). 25 of 36 patients with SQ were positive for PD-L1. 17 were positive with a TPS value between 1 and 49, and 8 were positive with a TPS value higher than 50. 133 samples with AD PD-L1 positive and 97 PD-L1 negative were tested for EGFR and ALK, 33 and 14 respectively were positive for EGFR mutations (p = 0.15), with 45% for exon 19 deletions (p = 0.003), 5 and 0 respectively were positive for ALK translocations (p = 0.053). 210 of 342 patients were men and 132 were women, 117 and 64 were positive for PD-L1 expression respectively (p > 0.1). Conclusions: NSCLC with EGFR mutation showed a trend for higher frequency of positive PD-L1 expression and NSCLC harboring ALK rearrangement was significantly associated with PD-L1 expression. These findings might contribute to the understanding of the regulation of PD-L1 expression in lung cancer and its relation to ALK expression and EGFR mutation.

Assessment of EGFR mutation status in matched plasma and tumor tissue of NSCLC patients.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e20032-e20032
Author(s):  
Qin Feng
Keyword(s):  
Tumor Tissue ◽  
Egfr Mutation ◽  
Circulating Tumor Dna ◽  
Egfr Mutations ◽  
Amplification Refractory Mutation System ◽  
Circulating Dna ◽  
Mutation Status ◽  
Nsclc Patients ◽  
Tumor Dna ◽  
Egfr Tkis

e20032 Background: Tumor tissue is currently used for EGFR testing non-small cell lung cancer (NSCLC) patients, but the detection of circulating tumor DNA (ctDNA) is being actively investigated as a new method for the detection and longitudinal monitoring of actionable mutations in plasma samples. Around 30% patients with EGFR mutation presented inconsistent status of EGFR mutation between in tissues and plasma. We compared EGFR mutation detection in circulating tumor DNA from blood to that in matched tissue. Methods: EGFR mutation status were assessed by the Human EGFR Gene Mutations Detection Kit (Beijing ACCB Biotech Ltd.) both in tissue and plasma. Retrospective analysis to evaluate the concordance of tissue and plasma EGFR determination for assessing eligibility for EGFR-TKIs therapy in NSCLC patients. 10 mL tubes of blood were collected from patients who never had been treated by EGFR TKI, and plasma circulating tumor DNA were extracted from plasma by Biomark Circulating DNA Kit. Qubit2.0 Fluorometer was used to make plasma circulating DNA tumor quantitation. The concentration of final DNA sample is ≦2ng/μl. Results: A total of 224 NSCLC patients were detected by Amplification Refractory Mutation System (ARMS), with 92 tissue positive and 49 blood positive. Results showed 53.3% sensitivity in overall samples, but 81.4% sensitivity in ⅢB~Ⅲ patients. The specificity is 100%. Conclusions: The high sensitivity and specificity between tissue and plasma EGFR determination supports the blood-based EGFR mutation testing to determinate the eligibility of NSCLC patients for EGFR-TKIs treatment, especialy in ⅢB~Ⅲ NSCLC patients. Blood, in particular plasma, is a good screening substitute when tumor tissue is absent or insufficient for testing EGFR mutations to guide EGFR TKIs treatment in patients with NSCLC. EGFR mutation positivity in blood could be used to recommend EGFR TKIs treatment, but the blood negativity should be confirmed with other sample, biopsy tissue, pleural effusion, etc..

Chemoimmunotherapy combination: Potential option for metastatic NSCLC patients with EGFR mutation resistant to osimertinib.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e20618-e20618
Author(s):  
Bo Yang ◽  
Yaping Long ◽  
Yi Hu
Keyword(s):  
Egfr Mutation ◽  
Acquired Resistance ◽  
Progression Free Survival ◽  
Egfr Mutations ◽  
Combination Group ◽  
Metastatic Nsclc ◽  
Number Of Patients ◽  
Grade 3 ◽  
Egfr Mutant ◽  
Nsclc Patients

e20618 Background: Osimertinib has been emerged as the standard selection in EGFR T790M-positive NSCLC patients who failed prior treatment with EGFR TKIs. However, acquired resistance to osimertinib is a growing clinical challenge. Despite the significant antitumor activity of Chemoimmunotherapy (CIT) combinations in NSCLC, clinical benefit in patients with EGFR mutations has not been shown obviously. Our objective was to assess the effectiveness and tolerability of CIT for metastatic EGFR-mutant NSCLC patients with acquired resistance to Osimertinib. Methods: We conducted a retrospective study in patients with sensitizing EGFR-mutant NSCLC who were resistant to Osimertinib and received anti-PD1 immunotherapy combined with chemotherapy at Chinese PLA General Hospital. Progression-free survival (PFS), overall survival (OS), overall response rate (ORR), and toxicities were examined. Results: Between Oct 2015 and Nov 2018, 11 patients were available for analysis, 45.5% male, 45.5% ECOG PS 0-1, median age 54 years, all pts who failed treatment with Osimertinib had received previously targeted therapies. In this CIT combination group, 6 [54.5%] of 11 pts received pembrolizumab and 5[54.5%] of 11 pts received Nivolumab anti-PD1 therapy, 8 [72.7%] of 11 pts received mono-chemotherapy and 3 [27.3%] of 11 pts received platinum-based doublet chemotherapy. The median PFS was 7.47 months (95% CI 3.04 to 11.89). Despite Median OS was not reached, the OS rate at one year was 6 [54.5%] of 11. The ORR was 5 [45.5%] of 11. Treatment-related adverse events (TRAE) of grade 3 or higher were reported in 6 [54.5%] of 11 patients. The most common grade 3 or worse TRAEs were fatigue (3 [27.3%] of 11) and anemia (3 [27.3%] of 11); The following ≥Grade 3 TRAEs occurred once: decreased neutrophil count, acute kidney injury, gastrointestinal bleeding. One patient discontinued treatment because of immune-associated gastroenteritis. Conclusions: In metastatic NSCLC patients with activating EGFR mutation resistant to Osimertinib, our single institution real-world experience in Chemoimmunotherapy combination shows promising activity and acceptable toxicity profile. Given the small number of patients studied, further clinical trials are warranted.

Lungful: An observational prospective study to assess the molecular epidemiology of EGFR mutations upon progression on or after first line EGFR-TKI therapy, in real-life clinical settings in Greece.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e21641-e21641
Author(s):  
Giannis Socrates Mountzios ◽  
Dimitrios Mavroudis ◽  
Epaminondas Samantas ◽  
Anna Koumarianou ◽  
Evangelos Georgios Konstantinos Fergadis ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Second Generation ◽  
Egfr Mutation ◽  
Locally Advanced ◽  
Real Life ◽  
Egfr Mutations ◽  
Liquid Biopsies ◽  
T790m Mutation ◽  
Nsclc Patients ◽  
Egfr Tki

e21641 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the gold standard 1st line strategy for non-small-cell lung cancer (NSCLC) patients with activating EGFR mutations (EGFRm), associated with improved survival outcomes and quality of life compared to chemotherapy. Despite the high response rate with first- and second- generation TKIs, most patients develop resistance to treatment and progress. The acquisition of T790M mutation in exon 20 is considered the most common resistance mechanism. This study aims to investigate the molecular epidemiology of EGFR resistance mutations, focusing on T790M in EGFRm NSCLC patients treated with TKIs. Methods: The study included patients with locally advanced/metastatic EGFRm NSCLC who have progressed on or after 1st line treatment with first- or second- generation TKI. Samples either from plasma-based liquid biopsy and/or tissue re-biopsy were analysed using the Cobas EGFR Mutation Test v2. All patients signed informed consent and were enrolled between July 2017 and September 2019. Statistical analyses were performed using SAS software, Version 9.4. Results: Ninety-six eligible patients were enrolled. At the time of progression, T790M mutation was detected in 16.7%of the patients using plasma-based liquid biopsies. Among patients with negative T790M result, in plasma, tissue re-biopsy was performed in 22,7% with evaluable/valid results in 72.2% of them. T790M mutation was identified in 38.5% of re-biopsy samples. According to Cobas EGFR Mutation test results (combined plasma and tissue), T790M mutation was identified in 21.9% of the patients. Of T790M-positive patients 42.9% had previously received first and 57.1% second generation EGFR-TKI. Conclusions: Results from this study in real world clinical setting in Greece, show that EGFR-T790M acquired resistance positivity rate in plasma is lower compared to previous reports. Moreover, these data underline the challenges of implementing precision medicine using tissue re-biopsy in advanced/metastatic NSCLC. Clinical trial information: D133FR00126. [Table: see text]

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