Clinicopathologic characteristics of EGFR, KRAS, and ALK alterations in 6,595 lung cancers

Molecular Testing of Lung Cancers

Targeted therapies guided by molecular diagnostics have become a standard treatment of lung cancer. Epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements are currently used as the best predictive biomarkers for EGFR tyrosine kinase inhibitors and ALK inhibitors, respectively. Besides EGFR and ALK, the list of druggable genetic alterations has been growing, including ROS1 rearrangements, RET rearrangements, and MET alterations. In this situation, pathologists should carefully manage clinical samples for molecular testing and should do their best to quickly and accurately identify patients who will benefit from precision therapeutics. Here, we grouped molecular biomarkers of lung cancers into three categories—mutations, gene rearrangements, and amplifications—and propose expanded guidelines on molecular testing of lung cancers.

Pulmonary adenocarcinoma with mucin production modulates phenotype according to common genetic traits: a reappraisal of mucinous adenocarcinoma and colloid adenocarcinoma

Whether invasive mucinous adenocarcinoma (IMA) and colloid adenocarcinoma (ICA) of the lung represent separate tumour entities, or simply lie within a spectrum of phenotypic variability, is worth investigating. Fifteen ICA, 12 IMA, 9 ALK‐rearranged adenocarcinomas (ALKA), 8 non‐mucinous KRAS‐mutated adenocarcinomas (KRASA) and 9 mucinous breast adenocarcinomas (MBA) were assessed by immunohistochemistry for alveolar (TTF1, cytoplasmic MUC1), intestinal (CDX‐2, MUC2), gastric (membrane MUC1, MUC6), bronchial (MUC5AC), mesenchymal (vimentin), neuroendocrine (chromogranin A, synaptophysin), sex steroid hormone‐related (oestrogen and progesterone receptors), pan‐mucinous (HNF4A) and pan‐epithelial (keratin 7) lineage biomarkers and by targeted next generation sequencing (TNGS) for 50 recurrently altered cancer genes. Unsupervised clustering analysis using molecular features identified cluster 1 (IMA and ICA), cluster 2 (ALKA and KRASA) and cluster 3 (MBA) (p < 0.0001). Cluster 1 showed four histology‐independent sub‐clusters (S1 to S4) pooled by HFN4A and MUC5AC but diversely reacting for TTF1, MUC1, MUC2, MUC6 and CDX2. Sub‐cluster S1 predominantly featured intestinal‐alveolar, S2 gastrointestinal, S3 gastric and S4 alveolar differentiation. In turn, KRASA and ALKA shared alveolar lineage alongside residual MUC5AC expression, with additional focal CDX2 and diffuse vimentin, respectively. A proximal‐to‐distal scheme extending from terminal (TB) and respiratory (RB) bronchioles to alveolar cells was devised, where S3 originated from distal TB (cellular mucinous adenocarcinoma), S2 from proximal RB (secreting mucinous adenocarcinoma), S1 from intermediate RB (mucin lake‐forming colloid adenocarcinoma), S4 from distal RB (colloid alveolar adenocarcinoma), KRASA from juxta‐alveolar RB (KRAS‐mutated non‐mucinous adenocarcinoma) and ALKA from juxta‐bronchial alveolar cells (ALK‐translocated adenocarcinoma). TNGS analysis showed KRAS, LKB1, TP53, APC and CDKN2A mutation predominance. In conclusion, IMA and ICA are basket categories, which likely originate from distinct domains of stem/progenitor cells spatially distributed along bronchioles upon common molecular features and genetic alterations.

Nrf2 and Notch Signaling in Lung Cancer: Near the Crossroad

The transcription factor Nrf2 (NF-E2 related factor 2) is a master regulator of the cell antioxidant response associated with tumor growth and resistance to cytotoxic treatments. In particular, Nrf2 induces upregulation of cytoprotective genes by interacting with the closely situated AREs (Antioxidant Response Elements) in response to endogenous or exogenous stress stimuli and takes part to several oncogenic signaling pathways. Among these, the crosstalk with Notch pathway has been shown to enhance cytoprotection and maintenance of cellular homeostasis, tissue organization by modulating cell proliferation kinetics, and stem cell self-renewal in several organs. The role of Notch and Nrf2 related pathways in tumorigenesis is highly variable and when they are both abnormally activated they can synergistically cause neoplastic proliferation by promoting cell survival, differentiation, invasion, and metastases. NFE2L2, KEAP1, and NOTCH genes family appear in the list of significantly mutated genes in tumors in both combined and individual sets, supporting the crucial role that the aberrant Nrf2-Notch crosstalk might have in cancerogenesis. In this review, we summarize current knowledge about the alterations of Nrf2 and Notch pathways and their reciprocal transcriptional regulation throughout tumorigenesis and progression of lung tumors, supporting the potentiality of putative biomarkers and therapeutic targets.

Effects of mutations in Wnt/β-catenin, hedgehog, Notch and PI3K pathways on GSK-3 activity-Diverse effects on cell growth, metabolism and cancer

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that participates in an array of critical cellular processes. GSK-3 was first characterized as an enzyme that phosphorylated and inactivated glycogen synthase. However, subsequent studies have revealed that this moon-lighting protein is involved in numerous signaling pathways that regulate not only metabolism but also have roles in: apoptosis, cell cycle progression, cell renewal, differentiation, embryogenesis, migration, regulation of gene transcription, stem cell biology and survival. In this review, we will discuss the roles that GSK-3 plays in various diseases as well as how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK, Wnt/beta-catenin, hedgehog, Notch and TP53. Mutations that occur in these and other pathways can alter the effects that natural GSK-3 activity has on regulating these signaling circuits that can lead to cancer as well as other diseases. The novel roles that microRNAs play in regulation of the effects of GSK-3 will also be evaluated. Targeting GSK-3 and these other pathways may improve therapy and overcome therapeutic resistance.

Not all epidermal growth factor receptor mutations in lung cancer are created equal: Perspectives for individualized treatment strategy

Somatic mutations in the epidermal growth factor receptor (EGFR) gene are present in approximately 20% (in Caucasians) to 40% (in East Asians) of adenocarcinomas of the lung. Targeted therapy for these lung cancers has been established based on evidence regarding mainly common mutations; that is, exon 19 deletions (Del19) and L858R. EGFR‐tyrosine kinase inhibitors (TKI), gefitinib, erlotinib or afatinib showed high objective response rates (ORR) of approximately 60%. Several studies suggested that Del19 might be more sensitive to EGFR‐TKI than L858R. On the other hand, it has been difficult to establish evidence for other less common mutations, accounting for 12% of all EGFR mutations, because there are many variants and many studies have excluded patients with these uncommon mutations. However, recent studies revealed that these rare genotypes could be targetable if appropriate TKI are selected. For example, G719X (X denotes A, S, C and so on), Del18, E709K, insertions in exon 19 (Ins19), S768I or L861Q showed moderate sensitivities to gefitinib or erlotinb with ORR of 30%–50%. However, afatinib appeared to be especially effective for these tumors. Although Ins20s (except for insFQEA) have been regarded as resistant mutations, osimertinib may be effective for rare subtypes of them and nazartinib (EGF816) is promising for the majority of them. For the further development of targeted therapy in all EGFR mutations, it is important to precisely detect targetable mutations, to select the most appropriate TKI for each mutation, and to continue investigating in vitro studies and collecting clinical data on even rare mutations.