非小细胞肺癌组织及胸水中EGFR基因TKD结构域突变的临床病理研究

目的检测非小细胞肺癌（NSCLC）EGFR基因酪氨酸蛋白激酶结构域（TKD）18—21外显子突变情况;比较常见突变（19号外显子的缺失突变及21号外显子错义突变-L858R）和非常见突变患者的临床病理改变。方法从91例NSCLC组织及胸水标本中提取基因组DNA;巢式PCR方法扩增EGFR基因18～21外显子;应用PCR-LIS-SSCP及直接测序方法检测EGFR基因18～21外显子突变情况;对存在常见及非常见突变患者的组织病理、酪氨酸蛋白激酶小分子抑制剂（TKIs）的治疗反应和预后等的临床病理改变进行分析。结果91例NSCLC患者中27例存在EGFR基因TKD突变,其中常见突变19例,突变率为20．9％（19／91）;非常见突变8例（其中4例为20号外显子的短片段插入突变）,突变率为8．8％（8／91）。两组患者组织学类型均为腺癌,且对TKIs治疗均有较好反应。2例非常见突变患者化疗时出现肺间质纤维化（ILD）。结论NSCLC患者EGFR基因TKD存在多种非常见突变;具有非常见突变的患者可能存在独特的临床病理改变。     

Transformation of non-small cell lung cancer into small cell lung cancer in a patient with advanced lung cancer: a case report

Targeted therapy in patients with epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) often fails because of drug resistance. Here, we report a 57-year-old male patient with stage IV small cell lung cancer (SCLC) transformation during targeted therapy. Chest computerized tomography (CT), hematoxylin and eosin histological examination, immunohistochemistry, allele refractory mutation system‐based quantitative polymerase chain reaction analysis of EGFR point mutations, and next-generation sequencing were performed for diagnosis and therapeutic efficacy evaluation. A combination of chest CT, histological examination, and immunohistochemistry confirmed the initial NSCLC diagnosis. Next-generation sequencing detected only EGFR exon 19 deletion (ex19del) before treatment and later identified EGFR exon20p.T790M point mutation, EGFR amplification, myc proto-oncogene (MYC) amplification, retinoblastoma 1 (RB1) mutation, and tumor protein 53 (TP53) mutation. Histology and immunohistochemistry revealed transformation from NSCLC to SCLC during treatment, which eventually returned to NSCLC. Drug resistance to targeted therapy for patients with NSCLC frequently occurs because of EGFR exon20p.T790M point mutation, TP53 mutation, RB1 mutation, and MYC amplification. These mutations are also the major determining factors of NSCLC outcomes. Therefore, next-generation sequencing should be performed to confirm drug efficacy during targeted therapy for NSCLC.     

Features of tumor-microenvironment images predict targeted therapy survival benefit in patients with EGFR-mutant lung cancer

Tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) are effective for many patients with lung cancer with EGFR mutations. However, not all patients are responsive to EGFR TKIs, including even those harboring EGFR-sensitizing mutations. In this study, we quantified the cells and cellular interaction features of the tumor microenvironment (TME) using routine H&E-stained biopsy sections. These TME features were used to develop a prediction model for survival benefit from EGFR TKI therapy in patients with lung adenocarcinoma and EGFR-sensitizing mutations in the Lung Cancer Mutation Consortium 1 (LCMC1) and validated in an independent LCMC2 cohort. In the validation data set, EGFR TKI treatment prolonged survival in the predicted-to-benefit group but not in the predicted-not-to-benefit group. Among patients treated with EGFR TKIs, the predicted-to-benefit group had prolonged survival outcomes compared with the predicted not-to-benefit group. The EGFR TKI survival benefit positively correlated with tumor-tumor interaction image features and negatively correlated with tumor-stroma interaction. Moreover, the tumor-stroma interaction was associated with higher activation of the hepatocyte growth factor/MET-mediated PI3K/AKT signaling pathway and epithelial-mesenchymal transition process, supporting the hypothesis of fibroblast-involved resistance to EGFR TKI treatment.     

Assessment of EGFR Mutation Status in Lung Adenocarcinoma by Immunohistochemistry Using Antibodies Specific to the Two Major Forms of Mutant EGFR

EGFR mutations are the best predictors of response to EGFR kinase inhibitors in lung adenocarcinoma. We evaluated two mutation-specific monoclonal antibodies for the detection of EGFR mutations by immunohistochemistry (IHC), generated respectively against the L858R mutant and the exon 19 mutant with the common 15bp/5AA deletion. These two mutations account for approximately 90% of all EGFR mutations. IHC staining performed on 218 paraffin-embedded lung adenocarcinomas was assessed on a 0 to 3+ scale, and positivity cutoffs of 1+ and 2+ were compared. All cases were studied by standard molecular methods for these two mutations, and selected cases were also studied using higher sensitivity molecular assays. The EGFR L858R mutant antibody showed a sensitivity of 95% and a positive predictive value (PPV) of 99% with a positivity cutoff of 1+ and a sensitivity of 76% and a PPV of 100% with a positivity cutoff of 2+. The EGFR exon 19 mutant–specific antibody showed reduced sensitivity for exon 19 deletions other than 15bp. A positivity cutoff of 1+ resulted in a sensitivity of 85% and a PPV of 99%, whereas a 2+ cutoff gave a sensitivity of 67% and a PPV of 100%. IHC with EGFR mutant–specific antibodies could be used as a screen to identify most candidates for EGFR inhibitors.Somatic mutations within the tyrosine kinase domain of EGFR are found in approximately 20% of lung adenocarcinomas and are the most reliable predictors of response to EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib and gefitinib (Sharma et al, 2007).¹ Multiple studies support that, in addition to their predictive value in treatment selection, EGFR mutations are also prognostic for survival benefit.^2,3 Specifically, patients with these tumors survive significantly longer on EGFR TKIs than with conventional cytotoxic chemotherapy.⁴ EGFR-mutant lung adenocarcinomas also form a distinct clinically favorable biological subset, regardless of EGFR TKI therapy.² Mutated EGFR is more often found in better differentiated adenocarcinomas with or without a bronchioloalveolar component.^5,6 It is virtually absent in other lung cancer subtypes except for adenosquamous carcinoma.^7,8In-frame deletions in exon 19 and the exon 21 L858R substitution are the most common EGFR mutations and, combined, represent approximately 90% of all mutants.⁹ Analysis for common EGFR mutations is now performed in many institutions to help direct treatment decisions. Direct DNA sequencing is a common detection method but has well-known sensitivity limitations depending on the proportion of tumor cells present in the material available for DNA extraction. Other DNA-based methods have been developed to address issues of sensitivity and turnaround time associated with direct sequencing.¹⁰ However, the cost and complexity of molecular methods has slowed their widespread implementation outside of major academic centers and commercial laboratories and drives the continued interest in less robust predictors of response such EGFR copy number and conventional immunohistochemistry (IHC) for total EGFR. IHC for total EGFR is an especially poor substitute as it correlates poorly or not at all with the presence of mutations.^11,12Another more challenging IHC strategy is to develop antibodies that react only with the mutant form of a given oncoprotein. Interest in this approach is driven by the fact that IHC is a technology available to essentially all pathology departments, can be automated, and can be performed on samples where the number or proportion of tumor cells poses challenges for molecular tests based on bulk DNA extraction from tissue. Cell Signaling Technology has recently developed two mutant-specific antibodies for IHC directed against the most common mutant forms of EGFR: the 15-bp/5-aa deletion (E746_A750del) in exon 19 and the L858R point mutation in exon 21.¹³ In the present study, we performed an independent evaluation of these two antibodies on a large series of lung adenocarcinomas with molecular data available for EGFR mutation status. We provide a careful assessment of putative false-positive and false-negative results, including a detailed analysis of how they relate to the molecular heterogeneity in EGFR exon 19 deletions and we propose an algorithm for their possible clinical implementation.     

Successful treatment of refractory lung adenocarcinoma harboring a germline BRCA2 mutation with olaparib: A case report

BACKGROUNDIn recent years, targeted therapy and immunotherapy have become important treatment strategies for patients with non-small cell lung cancer (NSCLC). However, the clinical evidence for successful off-label use of targeted drugs for patients with NSCLC following progression on multiple lines of treatment is still lacking.CASE SUMMARYWe describe a 62-year-old male patient with a right lung adenocarcinoma who harbored an EGFR exon 19 deletion mutation. He received gefitinib combined with six cycles of vinorelbine, cisplatin, and recombinant human endostatin as the first-line therapy. Then gefitinib was administered in combination with recombinant human endostatin as maintenance therapy, resulting in a progression-free survival (PFS) of 14 mo. Chemoradiotherapy was added following progression (enlarged brain metastases) on maintenance treatment. Unfortunately, the brain lesions were highly refractory and progressed again after 15 mo, at which time next-generation sequencing (NGS) of 1021 cancer-related genes was performed using peripheral blood to identify potential actionable mutations. NGS revealed that the patient harbored a BRCA2 germline mutation, the EGFR exon 19 deletion mutation disappeared, and no additional targetable genetic variant was detected. Therefore, the patient received olaparib combined with gefitinib and recombinant human endostatin, with a rapid and long-lasting clinical response (PFS = 13.5 mo).CONCLUSIONThis is a rare case of lung adenocarcinoma in a patient with a BRCA2 germline mutation who had long-term benefit from olaparib combination treatment, suggesting that NGS-based genetic testing may render the possibility of long-term survival in NSCLC patients after disease progression.     

EGFR mutations in non-small cell lung cancer: an audit from West China Hospital

Objectives: To discover the incidence and characteristics of EGFR mutations in non-small cell lung cancer (NSCLC) in a single, large cohort as a part of routine diagnostic investigations.

Methods: We reviewed EGFR mutations investigated by Amplification Refractory Mutation System (ARMS) PCR (covering 29 known mutations) using DNA samples from FFPE tissue or cell clot specimens in a total of 3894 cases of NSCLC analysed between 2012-2014.

Results: EGFR mutations are preferentially associated with adenocarcinomaand adenosquamous histology, particularly those well to moderately differentiated, and were significantly more common in female than male patients irrespective of histological subtypes. Exon 19 deletion (45.7%) and exon 21 L858R (45.6%) accounted for the vast majority of the EGFR mutations detected, with the remaining mutations being infrequent (<2%). Compound mutations were seen in 51 (3%) of the mutant cases, the combination of these compound mutations could be classified into three subgroups according to the potential impact of individual mutations on EGFR TKI therapy. Accordingly, 7 cases had both sensitive mutations, 4 cases harboured one sensitive and one less responsive /uncertain mutation, 19 cases contained one sensitive and one resistant change, and a further 21 cases had two less responsive /uncertain mutations.

Conclusion: Our data represents the largest EGFR mutation survey based on routine clinical diagnostic laboratory data from a single institution, it confirms the incidence and characteristics of EGFR mutations in NSCLC seen in Asian patients, and also unravels the combinatorial nature of rare compound EGFR mutations.     

Digital PCR detection of EGFR somatic mutations in non-small-cell lung cancer formalin fixed paraffin embedded samples

BackgroundDigital PCR (dPCR) is proposed to replace real time PCR and Sanger sequencing for detection and quantification of rare mutations, frequently unnoticed in the mass of tumoral cells. Screening of endothelial growth factor receptor (EGFR) mutations is mandatory before treatment with EGFR-targeted therapy with small-molecule tyrosine kinase inhibitors, which has been approved for the treatment of advanced non-small-cell lung cancer (NSCLC).ObjectiveIn order to establish a cost-effective method for detection of mutations, we optimized dPCR identification of EGFR mutations in exons 18–21, and determined dPCR sensitivity, limits of detection (LoD) and quantification (LoQ).MethodsFor clinical validation, we compared the performance of dPCR and castPCR in 57 NSCL formalin fixed paraffin embedded samples and 10 lung cancer-free formalin fixed paraffin embedded samples.ResultsEGFR mutations DEL19, p.L858R, p.G719X, p.L861Q and p.T790 M were detected by dPCR in 27 samples versus 11 detected by castPCR (p = 0.014). LoD was determined as 100 molecules of DNA/uL and LoQ as 1%. Most of the samples (87%) identified by competitive Allele-Specific TaqMan (castPCR) as wild-type and by dPCR as mutated, presented less than 10% mutated DNA molecules (mean 4.57%). Accuracy of dPCR was 94.44%, as measured with the assay recommended by the College of American Pathologists.ConclusionThese results indicated higher sensibility and specificity of dPCR for screening EGFR mutations in NSCLC biopsies, compared to castPCR.     

Dual targeting of EGFR can overcome a major drug resistance mutation in mouse models of EGFR mutant lung cancer

EGFR is a major anticancer drug target in human epithelial tumors. One effective class of agents is the tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. These drugs induce dramatic responses in individuals with lung adenocarcinomas characterized by mutations in exons encoding the EGFR tyrosine kinase domain, but disease progression invariably occurs. A major reason for such acquired resistance is the outgrowth of tumor cells with additional TKI-resistant EGFR mutations. Here we used relevant transgenic mouse lung tumor models to evaluate strategies to overcome the most common EGFR TKI resistance mutation, T790M. We treated mice bearing tumors harboring EGFR mutations with a variety of anticancer agents, including a new irreversible EGFR TKI that is under development (BIBW-2992) and the EGFR-specific antibody cetuximab. Surprisingly, we found that only the combination of both agents together induced dramatic shrinkage of erlotinib-resistant tumors harboring the T790M mutation, because together they efficiently depleted both phosphorylated and total EGFR. We suggest that these studies have immediate therapeutic implications for lung cancer patients, as dual targeting with cetuximab and a second-generation EGFR TKI may be an effective strategy to overcome T790M-mediated drug resistance. Moreover, this approach could serve as an important model for targeting other receptor tyrosine kinases activated in human cancers.     

Profile of the Roche cobas® EGFR mutation test v2 for non-small cell lung cancer

Introduction: The discovery of driver mutations in non-small cell lung cancer (NSCLC) has led to the development of genome-based personalized medicine. Fifteen to 20% of adenocarcinomas harbor an epidermal growth factor receptor (EGFR) activating mutation associated with responses to EGFR tyrosine kinase inhibitors (TKIs). Individual laboratories’ expertise and the availability of appropriate equipment are valuable assets in predictive molecular pathology, although the choice of methods should be determined by the nature of the samples to be tested and whether the detection of only well-characterized EGFR mutations or rather, of all detectable mutations, is required.

Areas covered: The EGFR mutation testing landscape is manifold and includes both screening and targeted methods, each with their own pros and cons. Here we review one of these companion tests, the Roche cobas® EGFR mutation test v2, from a methodological point of view, also exploring its liquid-biopsy applications.

Expert commentary: The Roche cobas® EGFR mutation test v2, based on real time RT-PCR, is a reliable option for testing EGFR mutations in clinical practice, either using tissue-derived DNA or plasma-derived cfDNA. This application will be valuable for laboratories with whose purpose is purely diagnostic and lacking high-throughput technologies.     

Profile of the therascreen® EGFR RGQ PCR kit as a companion diagnostic for gefitinib in non-small cell lung cancer

Introduction: Gefitinib is recently approved by the US Food and Drug Administration as a first-line treatment for non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. The therascreen® EGFR RGQ PCR Kit is approved as a companion diagnostic to select patients with EGFR exon 19 deletions and L858R mutation for treatment with gefitinib.

Areas covered: This article reviews the methods for detecting EGFR mutations, the technology and indication of the therascreen® kit, and the clinical utility of the assay in phase 3 and phase 4 clinical trials. Studies that compared the performance of the therascreen® kit with other assays and assessed the kit’s application in non-tissue samples are also discussed.

Expert commentary: The therascreen® kit is a highly sensitive real-time polymerase chain reaction test that provides standardised testing and automated interpretation of EGFR mutation status in formalin-fixed, paraffin-embedded (FFPE) tissue samples. Although not indicated for these applications, the test has also shown utility in detecting uncommon sensitizing EGFR mutations as well as mutations in non-tissue samples.     

Detection of EGFR-SEPT14 fusion in cell-free DNA of a patient with advanced gastric cancer: A case report

BACKGROUNDGastric cancer is the fifth most diagnosed cancer worldwide and the third most common cause of cancer-related death. In recent decades, increasing application of next-generation sequencing has enabled detection of molecular aberrations, including fusions. In cases where tissue is difficult to obtain, cell-free DNA (cfDNA) is used for detecting mutations to identify the molecular profile of cancer. Here, we report a rare case of EGFR-SEPT14 fusion detected from cfDNA analysis in a patient with gastric cancer. CASE SUMMARYA 49-year-old female diagnosed with advanced gastric cancer in July 2019 received capecitabine and then combination chemotherapy of ramucirumab and paclitaxel, but ascites was detected. The therapy was switched to nivolumab, but disease progression was observed on a positron emission tomography/computed tomography scan in May 2020. Therapy was discontinued, and cfDNA next-generation sequencing was immediately evaluated. All genomic variants, including fusions, were analyzed from cfDNA. The following somatic alterations were detected from the patient’s cfDNA: an APC frameshift mutation (NM_000038.5:c.6579del, p.V2194fs) with variant allele frequency of 0.5%, an EGFR amplification with a copy number of 17.3, and an EGFR-SEPT14 fusion with variant allele frequency of 45.3%. The site of the fusion was exon 24 of EGFR fused to exon 10 of SEPT14. The fusion was in-frame and considered to be protooncogenic. Although the patient refused to continue therapy, we suggest that EGFR-targeted therapies be tried in such future cases. CONCLUSIONThe expanded applications of the cfDNA assay may open a new horizon in treatment of patients with advanced gastric cancer.     

Epidermal Growth Factor Receptor: Pathway,Therapies, and Pipeline

Background

The epidermal growth factor receptor (EGFR) pathway is important in tumor growth, survival, and metastasis and is now the target of several therapeutic agents.

Objectives

This paper seeks to review the EGFR pathway, the study and use of EGFR-directed agents in non–small-cell lung cancer (NSCLC) and colorectal cancer (CRC), and related new drug development.

Methods

PubMed was searched for English-language articles by MeSH and title terms of EGFR published from 2006 to 2013, using the limits of clinical trials as well as reviews. Reference lists were assessed for relevant articles, and guidelines were searched. Clinicaltrials.gov and meeting abstracts were queried for investigational agents. Eligible papers included those concerning EGFR biology, NSCLC or CRC studies involving EGFR-directed agents, and/or investigational drugs targeting EGFR and/or associated pathways.

Results

The activity of oral tyrosine kinase inhibitors (TKIs) against EGFR has improved survival in NSCLC, and these agents particularly effective in cancers with an EGFR mutation. Resistance to TKIs is most commonly related to a second, T790M, mutation, or to MET amplification, with newer agents directed against these mechanisms. Conversely, in CRC, TKIs have been ineffective, whereas monoclonal antibodies have improved survival. Both primary and secondary KRAS mutations in CRC abrogate mAb effectiveness. Several targets, including MET, BRAF, and PI3K, may serve useful in combination with anti-EGFR drugs.

Conclusions

Exploitation of EGFR-directed therapies has offered improvement in survival and quality of life in NSCLC and CRC. New therapies directed at EGFR may offer further improvements. However, resistance mechanisms suggest that combination therapies or multitargeted agents will be crucial in making significant future advances.     

非小细胞肺癌组织EGFR/ALK/ROS1基因联合检测的临床意义

目的 探讨非小细胞肺癌(NSCLC)患者表皮生长因子受体(EGFR),间变性淋巴瘤激酶(ALK)和肉瘤致癌因子-受体酪氨酸激酶(ROS1)三种基因突变联合检测的临床意义。方法 收集2017年1月～2018年7月患者NSCLC组织标本146例,采用过柱法提取DNA和RNA,突变检测采用RT-PCR法和扩增阻滞突变系统(ARMS)法。结果 EGFR/ALK/ROS1三联检的突变频率为41.8%(61/146),明显高于单基因检测突变率:EGFR(33.6%,49/146),ALK(6.8%,10/146)和ROS1(2.7%,4/146)。EGFR的不同突变类型的检出率如下:19Del 52.9%(27/51),L858R 41.2%(21/51),G719X,L861Q 5.9%(3/51); 其中还检出四例双突变标本:19Del+ L858R(1例),19Del+G719X,L861Q(1例),ALK+19Del(1例),ROS1+L858R(1例)。EGFR/ALK/ROS1阳性标本中女性(56.7%,30/53)明显高于男性(33.3%,31/93),两者比较差异有统计学意义(χ²=7.516,P=0.006),肺腺癌(47.9%,58/121)明显高于鳞癌(4.8%,1/21),差异具有统计学意义(χ²=13.733,P=0.000)。不同来源组织突变检出率为:手术切除肿瘤组织标本41.0%(32/78),细针穿刺活检及支气管镜刷检细胞学等标本43.4%(23/53),胸腔积液标本40.0%(6/15),三者比较差异无统计学意义(P>0.05)。结论 在NSCLC基因突变中:EGFR/ALK/ROS1三联检的突变频率明显高于EGFR,ALK和ROS1单基因检测。EGFR常见突变基因为19Ex Del和21Ex L858R。女性突变率明显高于男性。EGFR/ALK/ROS1的联合检测可一次获得更多基因突变信息,为靶向用药提供更多选择,尤其是对于临床稀有标本意义更大。     

Therapy-related myeloid leukemia during erlotinib treatment in a non-small cell lung cancer patient: A case report

BACKGROUNDEpidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are tolerable drugs used for patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC). Serious adverse reactions are uncommon compared with cytotoxic drugs.CASE SUMMARYA 52-year-old man presented with general weakness and cytopenia. He had been taking erlotinib for 11 mo to treat NSCLC. The pathological diagnosis from the right upper lobe mass was adenocarcinoma with an EGFR mutation in exon 21 (L858R). He had previously received paclitaxel/carboplatin, gemcitabin/ vinorelbine chemotherapy, stereotactic radiosurgery for brain metastasis, and whole-brain radiotherapy as treatment for NSCLC. We diagnosed the patient with acute myeloid leukemia (AML). During the induction and consolidation chemotherapy for AML, the erlotinib was discontinued. When complete remission of the AML was achieved, since the lung masses were increased, pemetrexed/ cisplatin for the NSCLC was initiated. After two cycles of chemotherapy, the cytopenia was prolonged. AML relapse occurred with the same karyotype.CONCLUSIONTherapy-related acute myeloid neoplasm (t-MN) is a rare but fatal late complication. Although a patient may be taking EGFR-TKIs, the possibility of t-MN should be considered. Further studies are needed to determine whether EGFR-TKI usage is a predisposing factor for t-MN.     

高通量测序在非小细胞肺癌基因突变研究中的应用

目的对非小细胞肺癌(NSCLC)精准化诊疗相关的28种肿瘤驱动基因进行高通量测序,分析多基因突变与疾病临床特征的关系。方法收集重庆大学附属肿瘤医院2017年1月至2018年10月396例NSCLC患者标本,对EGFR、ALK、ROS1、KRAS、NRAS、HRAS、PIK3CA、TP53、PTEN、BRAF、HER2、RET、MET等28种基因进行高通量测序分析。结果EGFR基因突变占基因突变总检出例数的35.35%,且基因突变频率最高的前5个基因占总突变的63.89%,表现出明显的肿瘤主基因突变聚集现象。EGFR基因亚型同样呈明显的主次分布规律,其中最常见的突变亚型是19del、L858R,分别占45.00%、41.43%。EGFR基因的19del、L858R和20ins 3个亚型多为单突变,而T790M、G719X、S768I、L861Q等亚型则常表现为共突变。T790M伴随L858R突变常常是原发性突变,T790M与19del共突变则常常是获得性突变。EGFR突变标本发生其他多基因突变的检出率显著低于无EGFR突变标本,可能是因为EGFR基因突变抑制了其他基因发生突变。结论高通量测序可高效检测NSCLC患者与靶向治疗相关驱动基因的突变情况,可为研究多基因突变的内在关系及突变负荷提供有效工具,为临床医生制订NSCLC患者的精准诊疗方案提供有力支撑。     

Differential detection of KRAS mutations in codons 12 and 13 with a modified loop-hybrid (LH) mobility shift assay using an insert-type LH-generator

BackgroundThe loop-hybrid mobility shift assay (LH-MSA) was previously developed for the rapid detection of the EGFR mutation L858R for predicting clinical responses to gefitinib in lung cancer. Recently, clinical importance of determining KRAS mutations has been demonstrated in colorectal tumors as tumors harboring mutated KRAS genes were not responsive to therapy with EGFR-targeted antibodies such as cetuximab.MethodsWe developed a new version of the LH-MSA using an insert-type LH generator that was capable of detecting all 12 KRAS mutations in codons 12 and 13.ResultsFeasibility evaluation was performed with this new LH-MSA on 215 colorectal cancer specimens. KRAS codon 12 mutations were detected in 23% specimens and codon 13 mutations in 6.5% specimens by LH-MSA at a rate better than by direct sequencing.ConclusionsUsing the new method, the G13D mutation was readily distinguishable from other KRAS mutations in codon 12 and, therefore, would be advantageous for clinical applications.     

Targeting EGFRL858R/T790M and EGFRL858R/T790M/C797S resistance mutations in NSCLC: Current developments in medicinal chemistry

Both the first‐generation reversible epidermal growth factor receptor (EGFR) inhibitors gefitinib and erlotinib and the second‐generation covalent epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‐TKI) afatinib have significantly improved the survival of non‐small‐cell lung cancer (NSCLC) patients with activating EGFR mutations. However, a secondary EGFR^T790M mutation leads to the clinically acquired resistance to the first‐ and second‐generation EGFR‐TKIs drugs. A number of the third‐generation wild‐type sparing EGFR inhibitors, for example, WZ4002, CO1686, AZD9291, HM61713, EGF816, ASP8173, and PF0674775, have been developed, among which AZD9291 has been approved by US FDA for the treatment of NSCLC patients with EGFR^T790M. More recently, a tertiary EGFR^C797S mutation was reported as the dominant resistance mechanism to the third‐generation irreversible inhibitors. It is highly desirable to develop the fourth‐generation EGFR inhibitors. This review summarizes the mechanisms of acquired resistance and the latest medicinal chemistry advances on the third‐ and fourth‐generation EGFR inhibitors, with special attention being paid to the allosteric and reversible inhibitors combating the tertiary EGFR^C797S mutation.     

150例青海地区非小细胞肺癌患者表皮生长因子受体突变状态分析

目的探讨青海地区非小细胞肺癌(NSCLC)治疗过程中表皮生长因子受体(EGFR)突变状态。方法利用实时荧光Taqman探针法,采用PCR体外扩增,回顾性分析150例晚期NSCLC患者的临床特征、EGFR突变状态。结果 150例NSCLC患者标本检测发现EGFR(exon18)突变2例,突变率1.3%;EGFR(exon19)突变18例,突变率12.0%;EGFR(exon20)未检测出;EGFR(exon21)突变27例,突变率18.0%。结论青海地区NSCLC患者EGFR基因外显子19和21的突变(体细胞突变)率较高,可接受EGFR-TKIs治疗。     

Deficiency of the splicing factor RBM10 limits EGFR inhibitor response in EGFR-mutant lung cancer

Molecularly targeted cancer therapy has improved outcomes for patients with cancer with targetable oncoproteins, such as mutant EGFR in lung cancer. Yet, the long-term survival of these patients remains limited, because treatment responses are typically incomplete. One potential explanation for the lack of complete and durable responses is that oncogene-driven cancers with activating mutations of EGFR often harbor additional co-occurring genetic alterations. This hypothesis remains untested for most genetic alterations that co-occur with mutant EGFR. Here, we report the functional impact of inactivating genetic alterations of the mRNA splicing factor RNA-binding motif 10 (RBM10) that co-occur with mutant EGFR. RBM10 deficiency decreased EGFR inhibitor efficacy in patient-derived EGFR-mutant tumor models. RBM10 modulated mRNA alternative splicing of the mitochondrial apoptotic regulator Bcl-x to regulate tumor cell apoptosis during treatment. Genetic inactivation of RBM10 diminished EGFR inhibitor–mediated apoptosis by decreasing the ratio of (proapoptotic) Bcl-xS to (antiapoptotic) Bcl-xL isoforms of Bcl-x. RBM10 deficiency was a biomarker of poor response to EGFR inhibitor treatment in clinical samples. Coinhibition of Bcl-xL and mutant EGFR overcame the resistance induced by RBM10 deficiency. This study sheds light on the role of co-occurring genetic alterations and on the effect of splicing factor deficiency on the modulation of sensitivity to targeted kinase inhibitor cancer therapy.