BackgroundSomatic mutations in the kinase domain of the epidermal growth factor receptor tyrosine kinase gene EGFR are common in lung adenocarcinoma. The presence of mutations correlates with tumor sensitivity to the EGFR inhibitors erlotinib and gefitinib, but the transforming potential of specific mutations and their relationship to drug sensitivity have not been described.Methods and FindingsHere, we demonstrate that EGFR active site mutants are oncogenic. Mutant EGFR can transform both fibroblasts and lung epithelial cells in the absence of exogenous epidermal growth factor, as evidenced by anchorage-independent growth, focus formation, and tumor formation in immunocompromised mice. Transformation is associated with constitutive autophosphorylation of EGFR, Shc phosphorylation, and STAT pathway activation. Whereas transformation by most EGFR mutants confers on cells sensitivity to erlotinib and gefitinib, transformation by an exon 20 insertion makes cells resistant to these inhibitors but more sensitive to the irreversible inhibitor CL-387,785.ConclusionOncogenic transformation of cells by different EGFR mutants causes differential sensitivity to gefitinib and erlotinib. Treatment of lung cancers harboring EGFR exon 20 insertions may therefore require the development of alternative kinase inhibition strategies.

Oncogenic activation of tyrosine kinases is a common mechanism of carcinogenesis and, given the druggable nature of these enzymes, an attractive target for anticancer therapy. Here, we show that somatic mutations of the fibroblast growth factor receptor 2 (FGFR2) tyrosine kinase gene, FGFR2, are present in 12% of endometrial carcinomas, with additional instances found in lung squamous cell carcinoma and cervical carcinoma. These FGFR2 mutations, many of which are identical to mutations associated with congenital craniofacial developmental disorders, are constitutively activated and oncogenic when ectopically expressed in NIH 3T3 cells. Inhibition of FGFR2 kinase activity in endometrial carcinoma cell lines bearing such FGFR2 mutations inhibits transformation and survival, implicating FGFR2 as a novel therapeutic target in endometrial carcinoma.endometrial cancer ͉ fibroblast growth factor receptor 2 ͉ oncogene ͉ targeted therapy ͉ tyrosine kinase T yrosine kinases play a major role in transduction of proliferative signals and can become oncogenic when deregulated by somatic mutation (1). Somatically altered tyrosine kinases have proven to be tractable therapeutic targets in several tumor types; examples of successfully targeted tyrosine kinases include ABL1 in chronic myeloid leukemia (2), KIT in gastrointestinal stromal tumors (3), ERBB2 in breast cancer (4), and EGFR in non-small-cell lung cancer (5-7). The tyrosine kinase family has not been exhaustively studied in human cancer, and it is likely that additional tyrosine kinase therapeutic targets remain to be discovered.The fibroblast growth factor receptor (FGFR) tyrosine kinase family, which is comprised of four kinases that differentially respond to 18 FGF ligands (8, 9), has long been implicated in cancer. Translocations involving FGFR3, and activating somatic mutations in FGFR3, have been identified in multiple myeloma patients (10, 11), and translocations of FGFR1 have been found in patients with 8p11 myeloproliferative syndrome (12). Isolated cases of a missense mutation of FGFR4 in a lung adenocarcinoma patient and missense mutations of FGFR2 in a lung squamous cell carcinoma patient and gastric cancer patient have also been reported (13,14). In addition to these documented examples of somatic mutation of FGFR family members in cancer, a germ-line polymorphism in the second intron of FGFR2 was found to be associated with breast cancer in genomewide association studies (15,16).FGFR1-FGFR3 are characterized by alternative splicing of the mRNA encoding the third Ig-like repeat in the extracellular ligand-binding domain. This differential splicing determines ligand specificity such that isoforms expressed primarily in epithelial cells (IIIb) preferentially bind FGF ligands expressed by mesenchymal cells, and isoforms expressed primarily in mesenchymal cells (IIIc) preferentially bind FGF ligands expressed by epithelial cells (17)(18)(19). Alteration of this restricted expression pattern can lead to oncogenic transformation (20). Mutations in FGFR2 and FGF...

We assessed somatic alleles of six receptor tyrosine kinase genes mutated in lung adenocarcinoma for oncogenic activity. Five of these genes failed to score in transformation assays; however, novel recurring extracellular domain mutations of the receptor tyrosine kinase gene ERBB2 were potently oncogenic. These ERBB2 extracellular domain mutants were activated by two distinct mechanisms, characterized by elevated C-terminal tail phosphorylation or by covalent dimerization mediated by intermolecular disulfide bond formation. These distinct mechanisms of receptor activation converged upon tyrosine phosphorylation of cellular proteins, impacting cell motility. Survival of Ba/F3 cells transformed to IL-3 independence by the ERBB2 extracellular domain mutants was abrogated by treatment with small-molecule inhibitors of ERBB2, raising the possibility that patients harboring such mutations could benefit from ERBB2-directed therapy.HER2 | breast cancer | bladder cancer L ung cancer is the leading cause of cancer death, accounting for over 150,000 deaths annually in the United States alone (1). Current treatment options are thus inadequate for the majority of patients and additional therapies are needed. Mutationally activated oncogenes that promote tumorigenesis represent potential drug targets due to frequent dependency of tumor cells on such oncogenes (2, 3), and somatically altered receptor tyrosine kinases in particular have been successfully exploited as therapeutic targets in several cancers.The prototypical therapy targeted to a somatically activated tyrosine kinase oncogene is imatinib mesylate, which targets the BCR-ABL fusion protein in chronic myelogenous leukemia (4). Targeted therapies developed for lung cancer include gefitinib and erlotinib, small-molecule inhibitors of mutationally activated EGFR in lung adenocarcinoma (5-8), and crizotinib, a smallmolecule inhibitor of the EML4-ALK translocation product in lung adenocarcinoma (9). Trastuzumab, a monoclonal antibody inhibitor targeting ERBB2, and the small-molecule EGFR/ ERBB2 inhibitor lapatinib are effective in ERBB2-amplified patients with breast cancer (10, 11).The advent of next-generation sequencing technologies has enabled compilation of large somatic mutation datasets from cancer sequencing studies. Statistical methods that examine differences in gene mutation frequency can reveal evidence of positive selection; however, demonstration of the contribution of a mutated gene to tumorigenesis additionally requires functional validation. To identify new lung cancer oncogenes, we systematically assessed somatic alleles of significantly mutated receptor tyrosine kinase genes reported in patients with lung adenocarcinoma (12) for activity in cellular transformation assays.Although most receptor tyrosine kinase mutations tested failed to score, novel extracellular domain mutations of ERBB2 were oncogenic. Our results indicate a unique therapeutic opportunity for patients with lung and breast cancer who harbor extracellular domain mutations of ERBB2. Resul...

Reversible epidermal growth factor receptor (EGFR) inhibitors are the first class of small molecules to improve progression-free survival of patients with EGFR-mutated lung cancers. Second-generation EGFR inhibitors introduced to overcome acquired resistance by the T790M resistance mutation of EGFR have thus far shown limited clinical activity in patients with T790M-mutant tumors. In this study, we systematically analyzed the determinants of the activity and selectivity of the second-generation EGFR inhibitors. A focused library of irreversible as well as structurally corresponding reversible EGFR-inhibitors was synthesized for chemogenomic profiling involving over 79 genetically defined NSCLC and 19 EGFR-dependent cell lines. Overall, our results show that the growth-inhibitory potency of all irreversible inhibitors against the EGFR