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Purpose The role of epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKIs) in the management of persistent subsolid nodules (SSNs) is unclear. This study aimed to investigate the impact of EGFR-TKIs on concurrent SSNs in patients with stage IV non–small cell lung cancer (NSCLC).Materials and Methods Patients who received an EGFR-TKI for at least 1 month for stage IV NSCLC and had concurrent SSN(s) that had existed for at least 3 months on chest computed tomography were included in this retrospective study. Size change of each nodule before and after EGFR-TKI therapies were evaluated using a cutoff value of 2 mm; increase (≥ 2 mm), decrease (≤ –2 mm), and no change (–2 mm < size change < +2 mm).Results A total of 77 SSNs, 51 pure ground-glass (66.2%) and 26 part-solid nodules (33.8%), were identified in 59 patients who received gefitinib (n=45) and erlotinib (n=14). Among 58 EGFR mutation analysis performed for primary lung cancer, 45 (77.6%) were EGFR mutant. The proportions of decrease group were 19.5% (15/77) on per-nodule basis and 25.4% (15/59) on per-patient basis. Four SSNs (5.2%) disappeared completely. On per-patient based multivariable analysis, EGFR exon 19 deletion positivity for primary lung cancer was associated with a decrease after initial EGFR-TKI therapy (adjusted odds ratio, 4.29; 95% confidence interval, 1.21 to 15.29; p=0.025).Conclusion Approximately 20% of the concurrent SSNs decreased after the initial EGFR-TKI therapy. EGFR exon 19 deletion positivity for primary lung cancer was significantly associated with the size change of concurrent SSNs.

Supplementary Figure 1: FGFR2 probe for FISH

mp3 file (6.8 MB). In the inaugural edition of the Cancer Discovery podcast, Executive Editor Mark Landis talks with Matthew Meyerson about his paper, which describes the identification of the DDR2 kinase as a therapeutic target in squamous cell lung cancer.

Supplementary Table 1 from Mutations in the DDR2 Kinase Gene Identify a Novel Therapeutic Target in Squamous Cell Lung Cancer

Supplementary Figures 1-7 from Mutations in the DDR2 Kinase Gene Identify a Novel Therapeutic Target in Squamous Cell Lung Cancer

Supplementary Figure Legends 1-7 from Mutations in the DDR2 Kinase Gene Identify a Novel Therapeutic Target in Squamous Cell Lung Cancer

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PDF file - 303K, L704N or I941R cis mutation disrupts constitutive dimerization of mutant EGFR (S1); Tyrosine-phosphorylation is abrogated on L704N or I941R compound mutants of dimerization-dependent mutants (S2); Wild-type EGFR, but not Ex20Ins mutant are dependent on asymmetric dimerization for oncogenic transformation (S3); Tyrosine-phosphorylation on dimerization-independent mutants is significantly impaired by introduction of receiver-impairing or activator-impairing mutation (S4); Cell surface expression levels of various EGFR mutants in NIH-3T3 cells (S5); Activities of receiver monomers and activator monomers of wild-type EGFR (S6); Cell surface expression of mutant EGFR in stable cell lines (S7); Differential pharmacological effects of gefitinib and cetuximab against distinct mutant EGFR (S8); Generation and characterization of bitransgenic mice with inducible expression of EGFR Ex20Ins in lung compartments (S9); Cetuximab downregulates tyrosine phosphorylation on mutant EGFR in mouse tumors (S10).

Cancer stem cells (CSCs) have been implicated in the growth and progression of several types of human cancer. The technology to derive and establish CSCs in vitro could be a critical tool for under...

Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.

Simple Summary Triple-negative breast cancer (TNBC) is an intractable subset of breast cancer without an efficient therapeutic strategy due to the lack of tractable targets, such as the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Activation and/or amplification of epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT), and MAPK/ERK kinase (MEK)/ extracellular signal-regulated kinase (ERK) pathways is known in TNBC; however, interventions for these targets have not been successful to date. To explore a combinatorial strategy with existing clinical/preclinical protein kinase inhibitors (PKIs) in TNBC cells, we performed a series of cytotoxicity (cell viability) screenings with various PKIs in the presence figure of an EGFR inhibitor, gefitinib. The dual inhibition of AKT and MEK with gefitinib reduced the proliferation and colony formation of TNBC cells by inducing apoptosis. Our finding suggests a new approach for treating TNBC with a multiplex combination of PKIs. Abstract There is an unmet medical need for the development of new targeted therapeutic strategies for triple-negative breast cancer (TNBC). With drug combination screenings, we found that the triple combination of the protein kinase inhibitors (PKIs) of the epidermal growth factor receptor (EGFR), v-akt murine thymoma viral oncogene homolog (AKT), and MAPK/ERK kinase (MEK) is effective in inducing apoptosis in TNBC cells. A set of PKIs were first screened in combination with gefitinib in the TNBC cell line, MDA-MB-231. The AKT inhibitor, AT7867, was identified and further analyzed in two mesenchymal stem-like (MSL) subtype TNBC cells, MDA-MB-231 and HS578T. A combination of gefitinib and AT7867 reduced the proliferation and long-term survival of MSL TNBC cells. However, gefitinib and AT7867 induced the activation of the rat sarcoma (RAS)/ v-raf-1 murine leukemia viral oncogene homolog (RAF)/MEK/ extracellular signal-regulated kinase (ERK) pathway. To inhibit this pathway, MEK/ERK inhibitors were further screened in MDA-MB-231 cells in the presence of gefitinib and AT7867. As a result, we identified that the MEK inhibitor, PD-0325901, further enhanced the anti-proliferative and anti-clonogenic effects of gefitinib and AT7867 by inducing apoptosis. Our results suggest that the dual inhibition of the AKT and MEK pathways is a novel potential therapeutic strategy for targeting EGFR in TNBC cells.

The emergence of the T790M gatekeeper mutation in the Epidermal Growth Factor Receptor (EGFR) gene is an important mechanism that can lead to the acquired resistance to EGFR-targeted tyrosine kinase inhibitors such as erlotinib or gefitinib. These drugs have been used in treating a subset of non-small cell lung cancer (NSCLC) patients harboring EGFR activating mutations. Here we investigated the paths leading to the acquisition of the T790M mutation by establishing an erlotinib resistant PC9 cell model harboring ectopically introduced EGFR cDNA. We detected the emergence of T790M mutation within the EGFR cDNA in a subset of erlotinib resistant PC9 cell models through Sanger sequencing and droplet digital PCR-based methods, demonstrating that T790M mutation can emerge via de novo events following treatment with erlotinib. In addition, we show that the de novo T790M bearing erlotinib resistant PC9 cells are sensitive to the 3rd generation EGFR-targeted drug, WZ4002. Furthermore, GFP-based competition cell proliferation assays reveal that PC9 cells ectopically expressing EGFR mutant become more rapidly resistant to erlotinib than parental PC9 cells through the acquisition of the T790M mutation. Taken together, we believe that our findings expand upon the previous notion of evolutionary paths of T790M development, providing an important clue to designing a therapeutic strategy to overcome drug resistance.

Aberrant activation of cancer-derived mutants of the epidermal growth factor receptor (EGFR) is closely associated with cancer pathogenesis and is thought to be mediated through multiple tyrosine phosphorylations within the C-terminal domain. Here, we examined the consequences of the loss of these C-terminal phosphorylation sites on cellular transformation in the context of lung-cancer-derived L858R, exon 19 deletion and exon 20 insertion mutant EGFR. Oncogenic EGFR mutants with substitution of the 10 potential C-terminal tyrosine autophosphorylation sites for phenylalanine (CYF10) were still able to promote anchorage-independent growth in soft agar at levels comparable to the parental L858R or exon19 deletion or exon 20 insertion mutants with intact autophosphorylation sites. Furthermore, these CYF10 mutants retained the ability to transform Ba/F3 cells in the absence of IL-3. Bead-based phosphorylation and immunoprecipitation analyses demonstrated that key EGFR-associated proteins-including Grb2 and PLC-γ-are neither phosphorylated nor bound to CYF10 mutants in transformed cells. Taken together, we conclude that tyrosine phosphorylation is not required for oncogenic activity of lung-cancer-derived mutant EGFR, suggesting these mutants can lead to cellular transformation by an alternative mechanism independent of EGFR phosphorylation.

Background Understanding the genomic determinants associated with metastasis in colorectal cancers (CRCs) provides crucial clues for improving patient care. Patients and methods In this study, we performed whole-exome sequencing as well as RNA sequencing analyses on five pairs of primary and liver metastasized samples from CRC patients together with blood/normal control samples for each pair. Results We identified genomic deletions in the region of 8p21-23 (q value Conclusion Taken together, our findings uncovered various genomic alterations potentially leading to metastasis in CRC and provide important insights into the development of potential therapeutic targets for preventing metastatic progression of CRC.

Identification of potent agonists of odorant receptors (ORs), a major class of G protein-coupled receptors, remains challenging due to complex receptor–ligand interactions. ORs are present in both olfactory and non-chemosensory tissues, indicating roles beyond odor detection that may include modulating physiological functions in non-olfactory tissues. Selective and potent agonists specific for particular ORs can be used to investigate physiological functions of ORs in non-chemosensory tissues. In this study, we designed and synthesized novel synthetic dehydroacetic acid analogues as agonists of odorant receptor 895 (Olfr895) expressed in bladder. Among the synthesized analogues, (E)-3-((E)-1-hydroxy-3-(piperidin-1-yl)allylidene)-6-methyl-2H-pyran-2,4(3H)-dione (10) exhibited extremely high agonistic activity for Olfr895 in Dual-Glo luciferase reporter (EC50=9 nm), Ca2+ imaging, and chemotactic migration assays. Molecular docking and site-directed mutagenesis studies suggested that a combination of hydrophilic and hydrophobic interactions is central to the selective and specific binding of 10 to Olfr895. The design of agonists armed with both hydrophilic and hydrophobic portions could therefore lead to highly potent and selective ligands for ectopic ORs.

Somatic mutations of epidermal growth factor receptor (EGFR) occur in ~3% of colorectal cancer (CRC) patients. Here, through systematic functional screening of 21 recurrent EGFR mutations selected from public data sets, we show that 11 colon cancer-derived EGFR mutants (G63R, E114K, R165Q, R222C, S492R, P596L, K708R, E709K, G719S, G724S and L858R) are oncogenic and able to transform cells in a ligand-independent manner. We demonstrate that cellular transformation by these mutants requires receptor dimerization. Importantly, the EGF-induced and constitutive oncogenic potential of these EGFR mutants are inhibited by cetuximab or panitumumab in vivo and in vitro. Taken together, we propose that a subset of EGFR mutations can serve as genomic predictors for response to anti-EGFR antibodies and that metastatic CRC patients with such mutations may benefit from these drugs as part of the first-line therapy.

Therapies targeting the tyrosine kinase activity of Epidermal Growth Factor Receptor (EGFR) have been proven to be effective in treating a subset of non-small cell lung cancer (NSCLC) patients harboring activating EGFR mutations. Inevitably these patients develop resistance to the EGFR-targeted tyrosine kinase inhibitors (TKIs). Here, we performed integrated genomic analyses using an in vitro system to uncover alternative genomic mechanisms responsible for acquired resistance to EGFR-TKIs. Specifically, we identified 80 genes whose expression is significantly increased in the erlotinib-resistant clones. RNAi-based systematic synthetic lethal screening of these candidate genes revealed that suppression of one upregulated transcript, SCRN1, a secernin family member, restores sensitivity to erlotinib by enhancing inhibition of PI3K/AKT signaling pathway. Furthermore, immunohistochemical analysis revealed increased levels of SCRN1 in 5 of 11 lung tumor specimens from EGFR-TKIs resistant patients. Taken together, we propose that upregulation of SCRN1 is an additional mechanism associated with acquired resistance to EGFR-TKIs and that its suppression serves as a novel therapeutic strategy to overcome drug resistance in these patients.

Targeting of activated epidermal growth factor receptor (EGFR) with therapeutic anti-EGFR monoclonal antibodies (mAbs) such as cetuximab and panitumumab has been used as an effective strategy in treatment of colorectal cancer (CRC). However, its clinical efficacy occurs only in the limited number of patients. Here, we performed whole-transcriptome analysis in xenograft mouse tumors induced by KRASG12D mutation-bearing LS174T CRC cells following treatment with either cetuximab or PBS. By integrated analyses of differential gene expression with TCGA and CCLE public database, we identified TNS4, overexpressed in CRC patients and KRAS mutation-harboring CRC cell lines, significantly downregulated by cetuximab. While ablation of TNS4 expression via shRNA results in significant growth inhibition of LS174T, DLD1, WiDr, and DiFi CRC cell lines, conversely, its ectopic expression increases the oncogenic growth of these cells. Furthermore, TNS4 expression is transcriptionally regulated by MAP kinase signaling pathway. Consistent with this finding, selumetinib, a MEK1/2 inhibitor, suppressed oncogenic activity of CRC cells and this effect is more profound in combination with cetuximab. Altogether, we propose that TNS4 plays a crucial role in CRC tumorigenesis and that suppression of TNS4 would be an effective therapeutic strategy in treating a subset of cetuximab-refractory CRC patients including KRAS activating mutations. Citation Format: Sujin Kim, Nayoung Kim, Keunsoo Kang, Wonkyung Kim, Jonghwa Won, Jeonghee Cho. Whole transcriptome analysis identifies TNS4 as a key effector of cetuximab and a regulator of the oncogenic activity of KRAS mutant colorectal cancer cell lines [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1896.

Mig6 is a feedback inhibitor that directly binds, inhibits and drives internalization of ErbB-family receptors. Mig6 selectively targets activated receptors. Here we found that the epidermal growth factor receptor (EGFR) phosphorylates Mig6 on Y394 and that this phosphorylation is primed by prior phosphorylation of an adjacent residue, Y395, by Src. Crystal structures of human EGFR-Mig6 complexes reveal the structural basis for enhanced phosphorylation of primed Mig6 and show how Mig6 rearranges after phosphorylation by EGFR to effectively irreversibly inhibit the same receptor that catalyzed its phosphorylation. This dual phosphorylation site allows Mig6 to inactivate EGFR in a manner that requires activation of the target receptor and that can be modulated by Src. Loss of Mig6 is a driving event in human cancer; analysis of 1,057 gliomas reveals frequent focal deletions of ERRFI1, the gene that encodes Mig6, in EGFR-amplified glioblastomas.

// Jun Ho Yi 1, 5, * , Jiryeon Jang 1, * , Jeonghee Cho 2, * , In-Gu Do 3 , Mineui Hong 4 , Seung Tae Kim 1 , Kyoung-Mee Kim 4 , Sujin Lee 1 , Se Hoon Park 1 , Joon Oh Park 1, 4 , Young Suk Park 1 , Won Ki Kang 1 , Ho Yeong Lim 1 and Jeeyun Lee 1 1 Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 2 Samsung Genome Institute, Seoul, Korea 3 Department of Pathology, Kangbuk Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 4 Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 5 Division of Hematology-Oncology, Department of Medicine, Hanyang University Hospital, Seoul, Korea * These authors have contributed equally to this work Correspondence to: Ho Yeong Lim, e-mail: hoylim@skku.edu Jeeyun Lee, e-mail: jyunlee@skku.edu Keywords: gastric cancer, MerTK, patient-derived cells Received: February 28, 2014 Accepted: April 08, 2015 Published: April 20, 2015 ABSTRACT Introduction: The role of MerTK has not been assessed in gastric cancer (GC). The aim of this study was to identify a subgroup of GC patients with MerTK tumor overexpression, and to evaluate MerTK as a potential therapeutic target in this disease. Methods: Protein and mRNA expression of MerTK were evaluated, and other various in vitro analyses including shRNA transfection, cell cycle anslysis, MTS assay and colony forming assay were carried out with GC cell lines and GC patient-derived cells (PDCs). Results: shRNA-mediated knockdown of MerTK resulted in inhibition of cell growth, as well as increased cellular apoptosis in MerTK positive GC cells. Out of 192 GC patients, 16 (8.3%) patients showed strong protein expression and they had a significantly shorter overall survival compared to those with no MerTK expression. In 54 cases of GC PDCs, 4 cases (7.4%) showed mRNA overexpression, which was comparable to the protein expression rate. When we administered UNC1062, a novel MerTK-selective small molecular tyrosine kinase inhibitor, proliferation of MerTK overexpressing GC cells and PDCs were considerably inhibited. Conclusion: MerTK may be involved in GC carcinogenesis, and it could be a potential novel therapeutic target in GC patients.

// Angela K.J. Park 1,2 , Joshua M. Francis 3 , Woong-Yang Park 1,2 , Joon-Oh Park 4 and Jeonghee Cho 1,2 1 Samsung Genome Institute, Samsung Medical Center, Seoul, Republic of Korea 2 Samsung Advanced Institute for Health Sciences and Technology, SungKyunKwan University, Seoul, Republic of Korea 3 The Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA 4 Division of Hematology-Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea Correspondence to: Jeonghee Cho, email: // Keywords : epidermal growth factor receptor, EGFR targeted therapy, asymmetric dimerization, EGFR C-terminal domain deletion Received : December 30, 2014 Accepted : February 12, 2015 Published : March 12, 2015 Abstract Genomic alterations targeting the Epidermal Growth Factor Receptor ( EGFR ) gene have been strongly associated with cancer pathogenesis. The clinical effectiveness of EGFR targeted therapies, including small molecules directed against the kinase domain such as gefitinib, erlotinib and afatinib, have been proven successful in treating non-small cell lung cancer patients with tumors harboring EGFR kinase domain mutations. Recent large-scale genomic studies in glioblastoma and lung cancer have identified an additional class of oncogenic mutations caused by the intragenic deletion of carboxy-terminal coding regions. Here, we report that combinations of exonic deletions of exon 25 to 28 lead to the oncogenic activation of EGF receptor in the absence of ligand and consequent cellular transformation, indicating a significant role of C-terminal domain in modulating EGFR activation. Furthermore, we show that the oncogenic activity of the resulting C-terminal deletion mutants are efficiently inhibited by EGFR-targeted drugs including erlotinib, afatinib, dacomitinib as well as cetuximab, expanding the therapeutic rationale of cancer genome-based EGFR targeted approaches. Finally, in vivo and in vitro preclinical studies demonstrate that constitutive asymmetric dimerization in mutant EGFR is a key mechanism for oncogenic activation and tumorigenesis by C-terminal deletion mutants. Therefore, our data provide compelling evidence for oncogenic activation of C-terminal deletion mutants at the molecular level and we propose that C-terminal deletion status of EGFR can be considered as a potential genomic marker for EGFR-targeted therapy.

// Guhyun Kang 1,8,* Hongseok Yun 1,2,* , Choong-Hyun Sun 2 , Inho Park 2 , Seungmook Lee 2 , Jekeun Kwon 2 , Ingu Do 1,3,4 , Min Eui Hong 1,4,9 , Michael Van Vrancken 1 , Jeeyun Lee 5 , Joon Oh Park 5 , Jeonghee Cho 6 , Kyoung-Mee Kim 1,4 and Tae Sung Sohn 7 1 Department of Pathology & Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 2 Bioinformatics Laboratory, Samsung SDS Co., Ltd., Seoul, Korea 3 Samsung Cancer Research Institute, Samsung Medical Center, Seoul, Korea 4 Center for Cancer Companion Diagnostics, Samsung Medical Center, Seoul, Korea 5 Department of Medicine, Division of Hematology-Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 6 Samsung Genome Institute, Samsung Medical Center, Seoul, Korea 7 Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea 8 Department of Pathology, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea 9 Current address: Department of Pathology, Kangnam Sacred Heart Hospital, Hallym University, Seoul, Korea * These authors have contributed equally to this work Correspondence to: Kyoung-Mee Kim, email: // Tae Sung Sohn, email: // Keywords : high-throughput nucleotide sequencing; gastrointestinal stromal tumor; exome; transcriptome Received : January 30, 2015 Accepted : March 10, 2015 Published : March 30, 2015 Abstract Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. We sequenced nine exomes and transcriptomes, and two genomes of GISTs for integrated analyses. We detected 306 somatic variants in nine GISTs and recurrent protein-altering mutations in 29 genes. Transcriptome sequencing revealed 328 gene fusions, and the most frequently involved fusion events were associated with IGF2 fused to several partner genes including CCND1 , FUS , and LASP1 . We additionally identified three recurrent read-through fusion transcripts: POLA2 - CDC42EP2 , C8orf42 - FBXO25 , and STX16 - NPEPL1 . Notably, we found intragenic deletions in one of three exons of the VHL gene and increased mRNAs of VEGF , PDGF-β , and IGF-1/2 in 56% of GISTs, suggesting a mechanistic link between VHL inactivation and overexpression of hypoxia-inducible factor target genes in the absence of hypoxia. We also identified copy number gain and increased mRNA expression of AMACR , CRIM1 , SKP2 , and CACNA1E . Mapping of copy number and gene expression results to the KEGG pathways revealed activation of the JAK-STAT pathway in small intestinal GISTs and the MAPK pathway in wild-type GISTs. These observations will allow us to determine the genetic basis of GISTs and will facilitate further investigation to develop new therapeutic options.

Pazopanib is an orally bioavailable, ATP-competitive, multitargeted tyrosine kinase inhibitor mainly targeting VEGFR2 and PDGFR tyrosine kinases, but the biologic sequences of pazopanib activities beyond antiangiogenesis are poorly defined. We used a panel of 38 gastric cancer cell lines to test the efficacy of pazopanib. In a growth inhibition assay, genomic changes indicated that pazopanib had differential effects on cell growth. Treatment of the KATO-III, OCUM-2M, SNU-16, and HSC-39 gastric cancer cell lines harboring FGFR2 amplification with pazopanib resulted in marked decreases of cell survival with IC50 in ranges of 0.1 to 2.0 μmol/L, whereas the same treatment of those cell lines without FGFR2 amplification had no growth-inhibitory effects. In the ectopic FGFR2-expressing model, treatment with the indicated concentrations of pazopanib significantly inhibited cell growth and colony formation by FGFR2-expressing NIH 3T3 cells with wild-type (WT) FGFR2 and mutant FGFR2 (S252W). Pazopanib also selectively suppressed constitutive FGFR2 signaling and phosphorylation of downstream effectors. In cell-cycle analysis, FGFR2-amplified cells underwent cell-cycle arrest at the G1–S phase after pazopanib treatment, whereas there were no significant effects on cell-cycle progression in cells without FGFR2 amplification treated with pazopanib. In addition, pazopanib increased a substantial fraction of sub-G1 only in FGFR2-amplified cells. These findings show that the activation of FGFR2 signaling by amplification may be a critical mediator of cell proliferation in a small subset of gastric cancer patients and that pazopanib may provide genotype-correlated clinical benefits beyond the setting of highly vascular tumors. Mol Cancer Ther; 13(11); 2527–36. ©2014 AACR.

The targeting of activated epidermal growth factor receptor (EGFR) with therapeutic anti-EGFR monoclonal antibodies (mAbs) such as cetuximab and panitumumab has been used as an effective strategy in the treatment of colorectal cancer (CRC). However, its clinical efficacy occurs only in a limited number of patients. Here, we performed whole-transcriptome analysis in xenograft mouse tumors induced by KRASG12D mutation-bearing LS174T CRC cells following treatment with either cetuximab or PBS. Through integrated analyses of differential gene expression with TCGA and CCLE public database, we identified TNS4, overexpressed in CRC patients and KRAS mutation-harboring CRC cell lines, significantly downregulated by cetuximab. While ablation of TNS4 expression via shRNA results in significant growth inhibition of LS174T, DLD1, WiDr, and DiFi CRC cell lines, conversely, its ectopic expression increases the oncogenic growth of these cells. Furthermore, TNS4 expression is transcriptionally regulated by MAP kinase signaling pathway. Consistent with this finding, selumetinib, a MEK1/2 inhibitor, suppressed oncogenic activity of CRC cells, and this effect is more profound in combination with cetuximab. Altogether, we propose that TNS4 plays a crucial role in CRC tumorigenesis, and that suppression of TNS4 would be an effective therapeutic strategy in treating a subset of cetuximab-refractory CRC patients including KRAS activating mutations.

The emergence of the T790M gatekeeper mutation in the Epidermal Growth Factor Receptor (EGFR) gene is an important mechanism that can lead to the acquired resistance to EGFR-targeted tyrosine kinase inhibitors used in a subset of non-small cell lung cancer (NSCLC) patients harboring activating mutations. Here we investigated the paths leading to the acquisition of the T790M mutation by establishing an erlotinib resistant PC9 cell model harboring ectopically introduced EGFR cDNA. We detect the emergence of T790M mutation within the EGFR cDNA in a subset of erlotinib resistant PC9 cell models through Sanger sequencing and droplet digital PCR-based methods, confirming that T790M mutation can emerge via de novo events following treatment with erlotinib. In addition, we show that the de novo T790M bearing erlotinib resistant PC9 cells are sensitive to the 3rd generation EGFR-targeted drug, WZ4002. Furthermore, GFP-based competition cell proliferation assays reveal that PC9 cells ectopically expressing EGFR mutant become more dominantly resistant to erlotinib than parental PC9 cells by acquiring T790M mutation. Taken together, we believe that our findings expand upon the previous notion of evolutionary paths of T790M development, providing an important clue to designing a therapeutic strategy to overcome drug resistance. Citation Format: Sujin Kim, Angela KJ Park, Jeonghee Cho. T790M gatekeeper mutation emerges via de novo at the early stages of erlotinib treament in PC9 non-small cell lung cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1281.

Somatic mutations of Epidermal Growth Factor Receptor (EGFR) occur in ~3% of colorectal cancer patients. Here, through systematic functional screening of 21 recurrent EGFR mutations selected from public datasets, we show that 11 colon cancer-derived EGFR mutants; G63R, E114K, R165Q, R222C, S492R, P596L, K708R, E709K, G719S, G724S and L858R, are oncogenic, and able to transform cells in a ligand-independent manner. We demonstrate that cellular transformation by these mutants requires receptor dimerization. Importantly, the EGF-induced and constitutive oncogenic potential of these EGFR mutants are inhibited by cetuximab or panitumumab in vivo and in vitro. Taken together, we propose that a subset of EGFR mutations can serve as genomic predictors for response to anti-EGFR antibodies and that metastatic CRC patients with such mutations may benefit from these drugs as part of the first-line therapy. Citation Format: Nayoung Kim, Jeonghee Cho. Oncogenic EGFR mutations as genomic biomarkers for cetuximab and panitumumab response in colorectal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 858.

Kinase domain mutations of the EGF receptor (EGFR) are common oncogenic events in lung adenocarcinoma. Here, we explore the dependency upon asymmetric dimerization of the kinase domain for activation of lung cancer–derived EGFR mutants. We show that whereas wild-type EGFR and the L858R mutant require dimerization for activation and oncogenic transformation, the exon 19 deletion, exon 20 insertion, and L858R/T790M EGFR mutants do not require dimerization. In addition, treatment with the monoclonal antibody, cetuximab, shrinks mouse lung tumors induced by the dimerization-dependent L858R mutant, but exerts only a modest effect on tumors driven by dimerization-independent EGFR mutants. These data imply that different EGFR mutants show differential requirements for dimerization and that disruption of dimerization may be among the antitumor mechanisms of cetuximab. Cancer Res; 73(22); 6770–9. ©2013 AACR.

BACKGROUND: Recently, chromosomal rearrangements involving receptor tyrosine kinases (RTKs) have been described in common epithelial malignancies, including nonsmall cell lung cancer (NSCLC), colorectal cancer, and breast cancer. One of these RTKs, c-ros oncogene 1, receptor tyrosine kinase (ROS1), has been identified as a driver mutation in NSCLC, because its inhibition by crizotinib, an anaplastic lymphoma receptor tyrosine kinase (ALK)/met proto-oncogene hepatocyte growth factor receptor (MET)/ROS1 inhibitor, led to significant tumor shrinkage in ROS1-rearranged NSCLC. Currently, only human epidermal growth factor 2 (HER2)-targeted therapy in combination with chemotherapy has been successful in significantly prolonging the survival of patients with advanced gastric cancer (GC). There is a need for the discovery of additional novel targets in GC. METHODS: Anti-ROS1 immunohistochemistry (IHC) was used to screen 495 GC samples and was followed by simultaneous ROS1 break-apart fluorescence in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses in IHC-positive samples. Fusion partners in ROS1-rearranged GC were determined by RT-PCR. In all 495 samples, HER2 amplification was identified with FISH, and MET expression was identified by IHC. RESULTS: Twenty-three tumor samples were ROS1 IHC-positive. Three of 23 patients were ROS1 FISH positive, HER2 FISH negative, and negative for MET overexpression; and 2 of those 3 patients harbored a solute carrier family 34 (sodium phosphate), member 2 (SLC34A2)-ROS1 fusion transcripts. No fusion partner was identified in the third patient. Both patients who had SLC34A2-ROS1 transcripts had poorly differentiated histology with recurrence and death within 2 years of curative surgery. ROS1 IHC-positive status was not identified as an independent prognostic factor for overall survival. CONCLUSIONS: In this study, an SLC34A2-ROS1 rearrangement was identified in GC, and the results provide a rationale for investigating the clinical efficacy of ROS1 inhibitors in this unique molecular subset of GC. Cancer 2013. © 2013 American Cancer Society.

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.

Supplemental Digital Content is available in the text, There is limited data on miRNA expression in pancreatic neuroendocrine tumors (PanNETs). In this study, we aimed to identify miRNAs that could be potential prognostic biomarkers of PanNETs in patients who underwent curative surgery. For miRNA target screening, 2 primary PanNETs and corresponding liver metastases were screened for miRNA expression by the NanoString nCounter analysis. Candidate miRNAs were selected by ≥2-fold difference of expression between metastatic versus primary tumor. For miRNA target validation, quantitative real-time PCR was performed for candidate miRNAs on 37 PanNETs and matched nonneoplastic pancreata, and the miRNA levels were correlated with the clinicopathological features and patient survival data. Eight miRNAs (miRNA-27b, -122, -142–5p, -196a, -223, -590–5p, -630, and -944) were selected as candidate miRNAs. Only miR-196a level was significantly associated with stage, and mitotic count. When PanNETs were stratified into high (n = 10) and low (n = 27) miRNA-196a expression groups, miRNA-196a-high PanNETs were significantly associated with advanced pathologic T stage (50.0% vs 7.4%), N stage (50.0% vs 3.7%), higher mitotic counts (60.0% vs 3.7%), and higher Ki-67-labeling indices (60.0% vs 22.2%). In addition, high miRNA-196a expression was significantly associated with decreased overall survival (P = 0.046) and disease-free survival (P