Analysis of Driver Mutations in Female Non-Smoker Asian Patients with Pulmonary Adenocarcinoma

Previous studies have revealed that EGFR mutation and/or EML4?CALK gene fusion rate was higher in the non-smoker Asian females with pulmonary adenocarcinoma. The aim of this study is to determine the distribution of known oncogenic driver mutations in the female non-smoker Asian patients with pulmonary adenocarcinoma. 104 consecutively resected lung adenocarcinomas from 396 non-smoker females (less than 100 cigarettes in a lifetime) at a single institution (Tongji University, Shanghai, China) were analyzed for mutations in EGFR, EML4?ALK, KRAS, HER2, BRAF, and PIK3CA. 73 (70.2?%) tumors harbored EGFR mutations; among these, 28 were deletions in exon 19, 44 were L858R missense changes, and eight were T790M mutations. 10 (9.6?%) harbored EML4?ALK fusions, two harbored KRAS mutations, two harbored BRAF mutations, and two harbored PI3K mutations. A majority of the mutations were mutually exclusive, except two with EGFR mutation and BRAF mutation, one with EML4?ALK fusions and PI3K mutation. Thus, 82.7?% (86 of 104; 95?% CI, 75.4?C90.0?%) of lung adenocarcinomas from non-smoker females were found to harbor the well-known oncogenic mutations in five genes. Lung cancer in non-smoking Asian females is a distinct entity, with majority of this subgroup being developed by the oncogenic mutations. The prospective mutation examination in this population will be helpful for devising a targeted therapy for a majority of the patients.     

肺鳞癌和肺腺癌FGFR融合基因的临床意义

目的:探讨肺鳞癌和肺腺癌FGFR融合基因状态及其临床病理意义。方法:采用逆转录-聚合酶链反应(RT-PCR)和直接测序的方法检测2011年1月到2013年12月在我科行手术切除治疗的肺鳞癌和肺腺癌样本的FGFR融合基因,分析患者的临床病理学资料如性别、年龄、吸烟状况、肿瘤大小、病理类型、分化程度,并与对应样本的EGFR、KRAS、HER2、BRAF等常见驱动基因突变进行比较研究。结果:入组患者共512例,包括119例鳞癌和393例腺癌。FGFR融合基因的发生频率为1.2%(6/512),该分子亚型好发于病理证实为肺鳞癌(66.7%,p=0.029)、直径大于3厘米(83.3%,p=0.029)的男性(83.3%,p=0.028)吸烟患者(83.3%,p=0.038)。腺癌融合基因样本均含有实体病理亚型。结论:FGFR融合基因是肺鳞癌和肺腺癌的重要分子亚型,可能起驱动基因作用,具有该特征的肺癌亚群患者很可能将受益于FGFR靶基因研究与靶向治疗。     

Mixed responses to first-line alectinib in non-small cell lung cancer patients with rare ALK gene fusions: A case series and literature review

Anaplastic lymphoma kinase (ALK) fusion is a well-defined biomarker for ALK tyrosine kinase inhibitors (TKIs) treatment in non-small cell lung cancer (NSCLC). Alectinib, a second-generation ALK-TKI, has been shown to have significantly longer progression-free survival (PFS) than first-generation ALK inhibitors in untreated ALK-rearranged NSCLC patients. However, its clinical efficacy on rare ALK fusions remains unclear. Herein, two advanced NSCLC patients received first-line alectinib treatment, given their positive ALK fusion status as determined by immunohistochemistry (IHC) testing results. Patients showed limited clinical response (PFS: 4 months) and primary resistance to alectinib respectively. Molecular profiling using next-generation sequencing (NGS) further revealed a striatin (STRN)-ALK fusion in the first patient accompanied by MET amplification, and a LIM domain only protein 7 (LMO7)-ALK fusion in another patient without any other known oncogenic alterations. Both patients demonstrated improved survival after they switched to second-line crizotinib (PFS: 11 months) and ensartinib (PFS: 18 months), respectively, up till the last follow-up assessment. In conclusion, the clinical efficacy of ALK-TKIs including alectinib for lung cancer with uncommon ALK gene fusions is still under evaluation. This study and literature review results showed mixed responses to alectinib in NSCLC patients who harboured rare ALK fusions. Comprehensive molecular profiling of tumour is thus strongly warranted for precise treatment strategies.     

Chronic Obstructive Pulmonary Disease-Related Non-Small-Cell Lung Cancer Exhibits a Low Prevalence of EGFR and ALK Driver Mutations

Lung cancer and chronic obstructive pulmonary disease (COPD) are two major lung diseases. Epidermal growth factor receptor (EGFR) mutations, v‐Ki‐ras2 Kirsten rat sarcoma (KRAS) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements represent driver mutations that are frequently assessed on initial evaluation of non-small-cell lung cancer (NSCLC). The present study focused on the expression of driver mutations in NSCLC patients presenting with COPD and further evaluated the association between NSCLC and COPD. Data from 501 consecutive patients with histologically proven recurrent or metastatic NSCLC were analyzed retrospectively. The patients underwent spirometry and genotyping of EGFR, ALK, and KRAS in tissue samples. Patient characteristics and expression of driver mutations were compared between the COPD and non-COPD groups.Among 350 patients with spirometric results, 106 (30.3%) were diagnosed with COPD, 108 (30.9%) had EGFR mutations, 31 (8.9%) had KRAS mutations, and 34 (9.7%) showed ALK rearrangements. COPD was independently associated with lower prevalences of EGFR mutations (95% confidence interval [CI], 0.254–0.931, p = 0.029) and ALK rearrangements (95% CI, 0.065–0.600, p = 0.004). The proportions of EGFR mutations and ALK rearrangements decreased as the severity of airflow obstruction increased (p = 0.001). In never smokers, the prevalence of EGFR mutations was significantly lower in the COPD group than in the non-COPD group (12.7% vs. 49.0%, p = 0.002). COPD-related NSCLC patients exhibited low prevalences of EGFR mutations and ALK rearrangements compared with the non-COPD group. Further studies are required regarding the molecular mechanisms underlying lung cancer associated with COPD.     

Fluorescence In Situ Hybridization and Immunohistochemistry as Diagnostic Methods for ALK Positive Non-Small Cell Lung Cancer Patients

Background

Anaplastic Lymphoma Kinase (ALK) positivity represents a novel molecular target in a subset of Non-Small Cell Lung Cancers (NSCLC). We explore Fluorescence in situ Hybridization (FISH) and Immunohistochemistry (IHC) as diagnostic methods for ALK positive patients and to describe its prevalence and outcomes in a population of NSCLC patients.

Methods

NSCLC patients previously screened for Epidermal Growth Factor Receptor (EGFR) at our institution were selected. ALK positive patients were identified by FISH and the value of IHC (D5F3) was explored.

Results

ninety-nine patients were identified. Median age was 61.5 years (range 35–83), all were caucasians, eighty percent were adenocarcinomas, fifty-one percent were male and thirty-eight percent were current smokers. Seven (7.1%) patients were ALK positive by FISH, thirteen (13.1%) were EGFR mutant, and 65 (65.6%) were negative/Wild Type (WT) for both ALK and EGFR. ALK positivity and EGFR mutations were mutually exclusive. ALK positive patients tend to be younger than EGFR mutated or wt patients. ALK positive patients were predominantly never smokers (71.4%) and adenocarcinoma (71.4%). ALK positive and EGFR mutant patients have a better outcome than negative/WT. All patients with ALK FISH negative tumours were negative for ALK IHC. Out of 6 patients positive for ALK FISH with more tissue available, 5 were positive for ALK IHC and 1 negative.

Conclusions

ALK positive patients represent 7.1% of a population of selected NSCLC. ALK positive patients have different clinical features and a better outcome than EGFR WT and ALK negative patients. IHC is a promising method for detecting ALK positive NSCLC patients.     

非小细胞肺癌分子靶向药物治疗的研究进展

非小细胞肺癌(NSCLC)为最常见的肺癌病理类型,约占肺癌总数的 85%。大多数肺癌患者在确诊时已属晚期,失去手术机会, 保守治疗成为其重要治疗手段,但晚期肺癌患者的预后仍不理想。近年来,分子靶向治疗在肿瘤治疗领域取得重要进展,亦有研究显示 其在 NSCLC 的临床实践中发挥显著疗效。除表皮生长因子受体(EGFR)和间变淋巴瘤激酶(ALK)等主要基因突变之外,血管内皮生 长因子(VEGF)、ROS1、c-MET、RET、K-RAS、BRAF 也是目前 NSCLC 分子靶向治疗的相关靶点。综述 NSCLC 分子靶向药物治疗 的研究进展,旨在为该疾病的治疗提供参考。     

EML4-ALK 融合基因在非小细胞肺癌中的研究进展

肺癌是发病率和死亡率最高的恶性肿瘤,分子靶向治疗以其特异性高、副反应轻的特点正日益受到关注。近年来临床研究发现EML4-ALK融合基因是除EGFR突变及KRAS突变之外的另-个重要的酪氨酸激酶抑制剂的作用靶点,该融合基因在年轻、不吸烟或少吸烟、腺癌、无EGFR和KRAS突变的非小细胞肺癌患者中发生率较高,且该融合基因阳性者对酪氨酸激酶抑制剂耐药,对于ALK抑制剂(如克唑替尼)则有良好的治疗反应,关于该药的临床试验表明:总有效率达57%(46例确定为部分缓解,1例确定为完全缓解),估计6个月无进展生存概率为72%,常见的副反应是1、2级胃肠道反应。该基因及该药的发现为非小细胞肺癌患者带来了希望。     

Identification of new ALK and RET gene fusions from colorectal and lung cancer biopsies

Applying a next-generation sequencing assay targeting 145 cancer-relevant genes in 40 colorectal cancer and 24 non-small cell lung cancer formalin-fixed paraffin-embedded tissue specimens identified at least one clinically relevant genomic alteration in 59% of the samples and revealed two gene fusions, C2orf44-ALK in a colorectal cancer sample and KIF5B-RET in a lung adenocarcinoma. Further screening of 561 lung adenocarcinomas identified 11 additional tumors with KIF5B-RET gene fusions (2.0%; 95% CI 0.8-3.1%). Cells expressing oncogenic KIF5B-RET are sensitive to multi-kinase inhibitors that inhibit RET.     

Molecular Characteristics and Clinical Outcomes of EGFR Exon 19 C-Helix Deletion in Non–Small Cell Lung Cancer and Response to EGFR TKIs

Epidermal growth factor receptor (EGFR) exon 19 deletion (E19del) is the most common activating mutation in advanced non–small cell lung cancer (NSCLC) and associates with the sensitivity of EGFR tyrosine kinase inhibitors (TKIs) treatment. However, not all mutant patterns of E19del have been well studied for the limited coverage of regular EGFR mutation testing. Here, we performed a retrospective cohort study of the C-helix E19del in advanced NSCLC patients based on the screening data by the next-generation sequencing (NGS) platform. From May 2012 to December 2019, clinical information and specimen from 7544 consecutive advanced (IIIB/IV) NSCLC patients were collected and screened for EGFR gene mutations by NGS from multicenters in China. The molecular characteristics and responsiveness to first-line EGFR TKIs therapy in NSCLC patients with C-helix E19del were analyzed. The clinical characteristics were also compared between patients with classical E19del and C-helix E19del. Thirty-eight (2.6%) patients with C-helix E19del and 1400 (97.4%) patients with classical E19dels were identified from 1438 patients with E19del. No significant difference in clinical characteristics was observed between the C-helix E19del and classical E19del groups (P > .05), except for histology (P < .001). All 22 patients with C-helix E19del as p.S752_I759del, p.A750_E758del, p.A750_E758delinsP, p.T751_A755delinsNY, p.T751_I759delinsG, p.T751_I759delinsLD, p.T751_I759delinsN, p.T751_L760delinsNL, and p.T751_D761delinsLY reached the best response as partial response rate (72.7%), and the progression-free survival (PFS) was 12.0 months. The PFS after EGFR TKIs in patients with C-helix E19del tended to be longer than patients with classical E19del but has no statistical significance (12.0 months vs 8.5 months, P = .06). The C-helix E19del could be a positive biomarker for predicting response to EGFR TKIs in advanced NSCLC patients. NGS should be the appropriate platform to identify this rare population, especially when patients harbor no actionable driver mutation initially and are reluctant to accept chemotherapy as first-line therapy.     

Genetic determinants of lung cancer: Understanding the oncogenic potential of somatic missense mutations

BackgroundTreatment of lung cancer is getting more personalized nowadays and medical practitioners are moving away from conventional histology-driven empirical treatments, platinum-based chemotherapy, and other invasive surgical resections and have started adopting alternate therapies in which therapeutic targets are patient's molecular oncogenic drivers.AimThe aim of the current study is to extract meaningful information from the online somatic mutation data (retrieved from cBioPortal) of 16 most significantly mutated oncogenes in non-small-cell lung cancer (NSCLC), namely EGFR, NRAS, KRAS, HER2 (ERBB2), RET, MET, ROS1, FGFR1, BRAF, AKT1, MEK1 (MAP2K1), PIK3CA, PTEN, DDR2, LKB1 (STK11) and ALK, for improving our understanding of the pathobiology of the lung cancer that can aid decision-making on critical clinical and therapeutic considerations.MethodsUsing an integrated approach comprising 4 steps, the oncogenic potential of 661 missense non-synonymous single nucleotide polymorphisms (nsSNPs) in 16 genes was ascertained using 2059 NSCLC (1575 lung adenocarcinomas, 484 lung squamous cell carcinomas) patients' online mutation data. The steps used comprise sequence/structure homology-based prediction, scoring of conservation of mutated residues and positions, prediction of resulting molecular and functional consequences using machine-learning and structure-guided approach.ResultsOut of a total of 661 nsSNPs analyzed, a set of 29 nsSNPs has been identified as conserved high confidence mutations in 10 of 16 genes relevant to the under study. Out of 29 conserved high confidence nsSNPs, 4 nsSNPs (EGFR N1094Y, BRAF M620I, DDR2 R307L, ALK P1350T) have been found to be putative novel rare genetic markers for NSCLC.ConclusionsThe current study, the first of its kind, has provided a list of deleterious non-synonymous somatic mutations in a selected pool of oncogenes that can be considered as a promising target for future drug design and therapy for patients with lung adenocarcinomas and squamous cell carcinomas.     

Exploration of the gene fusion landscape of glioblastoma using transcriptome sequencing and copy number data

Background

RNA-seq has spurred important gene fusion discoveries in a number of different cancers, including lung, prostate, breast, brain, thyroid and bladder carcinomas. Gene fusion discovery can potentially lead to the development of novel treatments that target the underlying genetic abnormalities.

Results

In this study, we provide comprehensive view of gene fusion landscape in 185 glioblastoma multiforme patients from two independent cohorts. Fusions occur in approximately 30-50% of GBM patient samples. In the Ivy Center cohort of 24 patients, 33% of samples harbored fusions that were validated by qPCR and Sanger sequencing. We were able to identify high-confidence gene fusions from RNA-seq data in 53% of the samples in a TCGA cohort of 161 patients. We identified 13 cases (8%) with fusions retaining a tyrosine kinase domain in the TCGA cohort and one case in the Ivy Center cohort. Ours is the first study to describe recurrent fusions involving non-coding genes. Genomic locations 7p11 and 12q14-15 harbor majority of the fusions. Fusions on 7p11 are formed in focally amplified EGFR locus whereas 12q14-15 fusions are formed by complex genomic rearrangements. All the fusions detected in this study can be further visualized and analyzed using our website: http://ivygap.swedish.org/fusions.

Conclusions

Our study highlights the prevalence of gene fusions as one of the major genomic abnormalities in GBM. The majority of the fusions are private fusions, and a minority of these recur with low frequency. A small subset of patients with fusions of receptor tyrosine kinases can benefit from existing FDA approved drugs and drugs available in various clinical trials. Due to the low frequency and rarity of clinically relevant fusions, RNA-seq of GBM patient samples will be a vital tool for the identification of patient-specific fusions that can drive personalized therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-14-818) contains supplementary material, which is available to authorized users.     

Screening for EGFR and KRAS mutations in endobronchial ultrasound derived transbronchial needle aspirates in non-small cell lung cancer using COLD-PCR

EGFR mutations correlate with improved clinical outcome whereas KRAS mutations are associated with lack of response to tyrosine kinase inhibitors in patients with non-small cell lung cancer (NSCLC). Endobronchial ultrasound (EBUS)-transbronchial needle aspiration (TBNA) is being increasingly used in the management of NSCLC. Co-amplification at lower denaturation temperature (COLD)-polymerase chain reaction (PCR) (COLD-PCR) is a sensitive assay for the detection of genetic mutations in solid tumours. This study assessed the feasibility of using COLD-PCR to screen for EGFR and KRAS mutations in cytology samples obtained by EBUS-TBNA in routine clinical practice. Samples obtained from NSCLC patients undergoing EBUS-TBNA were evaluated according to our standard clinical protocols. DNA extracted from these samples was subjected to COLD-PCR to amplify exons 18-21 of EGFR and exons two and three of KRAS followed by direct sequencing. Mutation analysis was performed in 131 of 132 (99.3%) NSCLC patients (70F/62M) with confirmed lymph node metastases (94/132 (71.2%) adenocarcinoma; 17/132 (12.8%) squamous cell; 2/132 (0.15%) large cell neuroendocrine; 1/132 (0.07%) large cell carcinoma; 18/132 (13.6%) NSCL-not otherwise specified (NOS)). Molecular analysis of all EGFR and KRAS target sequences was achieved in 126 of 132 (95.5%) and 130 of 132 (98.4%) of cases respectively. EGFR mutations were identified in 13 (10.5%) of fully evaluated cases (11 in adenocarcinoma and two in NSCLC-NOS) including two novel mutations. KRAS mutations were identified in 23 (17.5%) of fully analysed patient samples (18 adenocarcinoma and five NSCLC-NOS). We conclude that EBUS-TBNA of lymph nodes infiltrated by NSCLC can provide sufficient tumour material for EGFR and KRAS mutation analysis in most patients, and that COLD-PCR and sequencing is a robust screening assay for EGFR and KRAS mutation analysis in this clinical context.     

Epidermal Growth Factor Receptor Exon 20 Mutation Increased inPost-Chemotherapy Patients with Non-Small Cell Lung Cancer Detected with Patients' Blood Samples

PURPOSE: Patients with non-small cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR)-mutations have excellent response to EGFR tyrosine kinase inhibitors (TKIs), and exon 20 mutation accounts for most of TKI drug resistance. Nested polymerase chain reaction (PCR) was used to detect EGFR exon 20 mutations of patients with NSCLC after chemotherapy. The same is being analyzed with patients' characteristics. METHODS: Peripheral blood samples were collected from 273 patients with NSCLC, including 143 with adenocarcinoma (ADC) and 130 with squamous cell carcinoma (SCC), after chemotherapy. DNA was extracted from whole blood for nested PCR amplification and purification. Sequencing was carried out in an automated 3730 sequencer, followed by analysis of EGFR exon 20 mutations from nested PCR products. RESULTS: The mutations of EGFR exon 20 were mainly point mutations in rs1050171 (c.2361A>G) and rs56183713 (c.2457G>A). The point mutation was 28.21%, 28.46%, and 27.97% in patients with NSCLC, ADC and SCC, respectively. Men had an equivalent mutation (27.18%) to women (30.77%). The mutation in smokers and nonsmokers was 27.68% and 29.17%, respectively. In unselected patients, there was no correlation between EGFR exon 20 mutations and patients' characteristics of age, gender, smoking history, histologic type, or tumor-node-metastasis (TNM) staging system. In subgroup analyses, the EGFR mutation of patients with SCC was correlated with TNM stage [P = .013; odds ratio = 1.758; 95% confidence interval (CI) = 1.125-2.747]. CONCLUSIONS: The data indicate that the chemotherapy may induce EGFR-TKI-resistant mutation in NSCLC cells and EGFR-TKI should be used in the early stage of NSCLC but not after chemotherapy.     

Spectrum of oncogenic driver mutations in lung adenocarcinomas from East Asian never smokers

Purpose

We previously showed that 90% (47 of 52; 95% CI, 0.79 to 0.96) of lung adenocarcinomas from East Asian never-smokers harbored well-known oncogenic mutations in just four genes: EGFR, HER2, ALK, and KRAS. Here, we sought to extend these findings to more samples and identify driver alterations in tumors negative for these mutations.

Experimental Design

We have collected and analyzed 202 resected lung adenocarcinomas from never smokers seen at Fudan University Shanghai Cancer Center. Since mutations were mutually exclusive in the first 52 examined, we determined the status of EGFR, KRAS, HER2, ALK, and BRAF in stepwise fashion as previously described. Samples negative for mutations in these 5 genes were subsequently examined for known ROS1 fusions by RT-PCR and direct sequencing.

Results

152 tumors (75.3%) harbored EGFR mutations, 12 (6%) had HER2 mutations, 10 (5%) had ALK fusions all involving EML4 as the 5′ partner, 4 (2%) had KRAS mutations, and 2 (1%) harbored ROS1 fusions. No BRAF mutation were detected.

Conclusion

The vast majority (176 of 202; 87.1%, 95% CI: 0.82 to 0.91) of lung adenocarcinomas from never smokers harbor mutant kinases sensitive to available TKIs. Interestingly, patients with EGFR mutant patients tend to be older than those without EGFR mutations (58.3 Vs 54.3, P = 0.016) and patient without any known oncogenic driver tend to be diagnosed at a younger age (52.3 Vs 57.9, P = 0.013). Collectively, these data indicate that the majority of never smokers with lung adenocarcinoma could benefit from treatment with a specific tyrosine kinase inhibitor.     

High MET copy number and MET overexpression: poor outcome in non-small cell lung cancer patients

The aim of this study was to evaluate the prevalence and prognostic role of increased gene copy number and protein expression of MET and EGFR in non-small cell lung cancer (NSCLC) patients. Samples were collected from 380 patients with surgically resected NSCLC, and fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) were performed. EGFR amplification and high polysomy (EGFR FISH-positive) were observed in 9.7% and 17.4% of the patients, respectively. EGFR was overexpressed (EGFR IHC-positive) in 19.2% of the patients. Neither EGFR FISH-positive nor EGFR IHC-positive status affected survival after resection. Increased MET copy number (MET FISH-positive by University of Colorado Cancer Center criteria) was observed in 11.1% of the patients (high polysomy, 8.7%; gene amplification, 2.4%). According to the Cappuzzo system, 7.1% of the patients were MET FISH-positive. MET FISH positivity was a negative prognostic factor, especially in patients with adenocarcinoma histology (p=0.040), female gender (p=0.010), old age (p=0.084), and EGFR FISH negativity (p=0.020) at the univariate level but not at the multivariate level. MET was overexpressed (MET IHC-positive) in 13.7% of the patients and associated with shorter overall and disease-free survival (p=0.010 and p=0.056, respectively). Multivariate analysis revealed that MET IHC-positive patients had a significantly increased risk of death (hazard ratio, 1.618; 95% confidence interval, 1.066-2.456; p=0.024). Increased MET copy number and MET overexpression are negative prognostic factors for surgically resected NSCLCs.     

Short-Term Responders of Non–Small Cell Lung Cancer Patients to EGFR Tyrosine Kinase Inhibitors Display High Prevalence of TP53 Mutations and Primary Resistance Mechanisms

Non–small cell lung cancer (NSCLC) with activating EGFR mutations in exon 19 and 21 typically responds to EGFR tyrosine kinase inhibitors (TKI); however, for some patients, responses last only a few months. The underlying mechanisms of such short responses have not been fully elucidated. Here, we sequenced the genomes of 16 short-term responders (SR) that had progression-free survival (PFS) of less than 6 months on the first-generation EGFR TKI and compared them to 12 long-term responders (LR) that had more than 24 months of PFS. All patients were diagnosed with advanced lung adenocarcinoma and harbored EGFR 19del or L858R mutations before treatment. Paired tumor samples collected before treatment and after relapse (or at the last follow-up) were subjected to targeted next-generation sequencing of 416 cancer-related genes. SR patients were significantly younger than LR patients (P < .001). Collectively, 88% of SR patients had TP53 variations compared to 13% of LR patients (P < .001). Additionally, 37.5% of SR patients carried EGFR amplifications compared to 8% of LR patients. Other potential primary resistance factors were also identified in the pretreatment samples of 12 SR patients (75%), including PTEN loss; BIM deletion polymorphism; and amplifications of EGFR, ERBB2, MET, HRAS, and AKT2. Comparatively, only three LR patients (25%) were detected with EGFR or AKT1 amplifications that could possibly exert resistance. The diverse preexisting resistance mechanisms in SR patients revealed the complexity of defining treatment strategies even for EGFR-sensitive mutations.