EML4-ALK在非小细胞肺癌中的检测及其临床意义

棘皮动物微管结合蛋白4(EML4)与间变淋巴瘤激酶(ALK)形成的融合基因被认为是非小细胞肺癌(NSCLC)新的分子靶点.最近,Ⅰ期和Ⅱ期临床研究运用ALK抑制剂治疗携带重组ALK基因的NSCLC患者的反应率达80%以上.因此,研究EML4-ALK的生物学特性、与临床病理特征的关系以及目前存在的问题,可为临床治疗此类患...     

Fluorescence In Situ Hybridization,Immunohistochemistry, and Next‐Generation Sequencing for Detection of EML4‐ALK Rearrangement in Lung Cancer

Background.

The U.S. Food and Drug Administration-approved method for detecting EML4-ALK rearrangement is fluorescence in situ hybridization (FISH); however, data supporting the use of immunohistochemistry (IHC) for that purpose are accumulating. Previous studies that compared FISH and IHC considered FISH the gold standard, but none compared data with the results of next-generation sequencing (NGS) analysis.

Materials and Methods.

We studied FISH and IHC (D5F3 antibody) systematically for EML4-ALK rearrangement in 51 lung adenocarcinoma patients, followed by NGS in case of discordance.

Results.

Of 51 patients, 4 were positive with FISH (7.8%), and 8 were positive with IHC (15.7%). Three were positive with both. NGS confirmed that four of the five patients who were positive with IHC and negative with FISH were positive for ALK. Two were treated by crizotinib, with progression-free survival of 18 and 6 months. Considering NGS as the most accurate test, the sensitivity and specificity were 42.9% and 97.7%, respectively, for FISH and 100% and 97.7%, respectively, for IHC.

Conclusion.

The FISH-based method of detecting EML4-ALK rearrangement in lung cancer may miss a significant number of patients who could benefit from targeted ALK therapy. Screening for EML4-ALK rearrangement by IHC should be strongly considered, and NGS is recommended in borderline cases. Two patients who were negative with FISH and positive with IHC were treated with crizotinib and responded to therapy.     

Concomitant EGFR Mutation and EML4-ALK Rearrangement in Lung Adenocarcinoma Is More Frequent in Multifocal Lesions

BackgroundThe coexistence of epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangement in patients with multifocal lung adenocarcinomas (LUAC) constitutes a rare molecular subtype of lung cancer. We aimed to investigate the intertumoral heterogeneity of pathologic and genetic characteristics of multifocal LUAC with EGFR/ALK co-alterations.Patients and MethodsA total of 1059 LUAC patients who underwent resection were investigated to screen for EGFR or ALK alterations using amplification refractory mutation system polymerase chain reaction and immunohistochemistry/fluorescence in situ hybridization. Molecular testing was extensively performed in patients with synchronous multifocal LUAC. Clonal evolution analysis was implemented using next-generation sequencing.ResultsA total of 97 multiple synchronous lesions were observed among 1059 LUAC patients. Patients with at least 1 sample harboring EGFR mutation or ALK rearrangement were 62.89% (61/97) and 14.43% (14/97), respectively. Patients with concomitant EGFR and ALK alterations were 4.71% (4/97). Comparatively, patients with unifocal LUAC harboring EGFR mutation, ALK rearrangement, and EGFR/ALK co-alterations were 58.25% (570/962), 6.44% (62/962), and 0.83% (8/962), respectively. The prevalence of EGFR/ALK co-alterations in the multifocal LUAC was significantly higher than that in the unifocal LUAC (4.71% (4/97) vs. 0.83% (8/962)). Furthermore, we present 4 cases of EGFR/ALK co-altered multifocal LUAC with different morphological and molecular patterns. In addition to radiographic, pathological, and molecular testing results, clonal evolutional analysis could also be used to distinguish intertumoral heterogeneity.ConclusionThe results highlight the importance of distinguishing synchronous primary tumors from intrapulmonary metastases, and of assessing the relative abundance of EGFR mutation and ALK rearrangement in patients with multifocal adenocarcinomas with EGFR/ALK co-alterations.     

非小细胞肺癌治疗的新靶点:EML4-ALK融合基因

3年前棘皮动物微管相关类蛋白4(echinoderm microtubule-associated protein-like 4,EML4)与间变性淋巴瘤激酶(anaplastic lymphoma kinase,ALK)融合基因被发现存在于部分非小细胞肺癌(non-small cell lung cancer,NSCLC)中。该融合基因常见于不吸烟的肺腺癌患者,有其独特的病理学特征,可以诱导肿瘤生成。ALK抑制剂能够作用于该基因的下游信号传导通路并拮抗其促肿瘤生成活性。本文旨在介绍EML4-ALK基因的结构、功能、生物学特征、检测方法及其在肺癌诊断治疗中的意义。