Aberrant Epidermal Growth Factor Receptor Research Articles

TMIC-83. ABERRANT EGFR ACTIVATION SUPPORTS ENHANCED TUMOR-MYELOID CROSSTALK AND IMPAIRS EFFECTOR T CELL INFILTRATION AND FUNCTION IN GLIOBLASTOMA

Abstract Glioblastoma (GBM) is known to display a highly suppressive tumor immune microenvironment (TIME) dominated by myeloid cells with low T cell infiltration. Aberrant epidermal growth factor receptor (EGFR) activation is observed in ~50% of GBM patients via amplification and the constitutively active EGFRvIII variant, however the impact of EGFR activation on the brain TIME and T cell-mediated anti-tumor immunity remains poorly understood. Single cell transcriptomic and receptor-ligand interaction analyses of paired newly diagnosed GBM tumor and intratumoral CD45+ immune cells revealed increased crosstalk between EGFR activated tumors and EGFR ligand-expressing tumor-associated myeloid cells. Therefore, a novel orthotopic murine EGFRvIII-expressing glioma model wherein the mEGFRvIII gene is under a tetracycline-off system (MADR-mEGFRvIII) was leveraged to identify how EGFR signaling impacts overall TIME composition and the phenotype of intratumoral and systemic T cells in vivo. Temporal flow cytometric immunophenotyping following tumor or mock (saline) implantation identified no significant shift in T cell infiltration within the brain or cervical lymph nodes (cLNs). In contrast, one week of doxycycline-mediated genetic EGFR ablation conferred a significant survival benefit and was associated with enhanced intratumoral T cell infiltration as well as diminished tumor-associated F4/80+ myeloid cells compared to vehicle treated animals. Further characterization revealed genetic EGFR ablation enhanced recruitment of CXCR3+, TNFα+, and TIGIT+ CD4 T cells to the tumor, while the prevalence of these populations contracted in CD4 and CD8 T cells within the draining cLNs. In vitro, pharmacologic EGFR inhibition enhanced antigen-specific Pmel-1 T cell killing of gp100-expressing MADR-mEGFRvIII tumor cells and was associated with increased IFNγ secretion by ELISA. Collectively, our work demonstrates that aberrant EGFR signaling promotes an immunosuppressive brain TIME with reduced T cell infiltration potentially via tumor-myeloid signaling. Targeting this oncogenic axis may therefore reprogram the TIME and directly enable enhanced trafficking of effector T cells to the tumor.

Cholangiocyte ciliary defects induce sustained epidermal growth factor receptor signaling.

The primary cilium, an organelle that protrudes from cell surfaces, is essential for sensing extracellular signals. With disturbed cellular communication and chronic liver pathologies, this organelle's dysfunctions have been linked to disorders, including polycystic liver disease and cholangiocarcinoma. The goal of this study was to elucidate the relationship between primary cilia and the crucial regulator of cellular proliferation, the epidermal growth factor receptor (EGFR) signaling pathway, which has been associated with various clinical conditions. The study identified aberrant EGFR signaling pathways in cholangiocytes lacking functional primary cilia using liver-specific intraflagellar transport 88 knockout mice, a Pkhd1 mutant rat model, and human cell lines that did not have functional cilia. Cilia-deficient cholangiocytes showed persistent EGFR activation because of impaired receptor degradation, in contrast to their normal counterparts, where EGFR localization to the cilia promotes appropriate signaling. Using histone deacetylase 6 inhibitors to restore primary cilia accelerates EGFR degradation, thereby reducing maladaptive signaling. Importantly, experimental intervention with the histone deacetylase 6 inhibitor tubastatin A in an orthotopic rat model moved EGFR to cilia and reduced ERK phosphorylation. Concurrent administration of EGFR and histone deacetylase 6 inhibitors in cholangiocarcinoma and polycystic liver disease cells demonstrated synergistic antiproliferative effects, which were associated with the restoration of functioning primary cilia. This study's findings shed light on ciliary function and robust EGFR signaling with slower receptor turnover. We could use therapies that restore the function of primary cilia to treat EGFR-driven diseases in polycystic liver disease and cholangiocarcinoma.

The impact of nitric oxide on HER family post-translational modification and downstream signaling in cancer.

The human epidermal growth factor receptor (HER) family consists of four members, activated by two families of ligands. They are known for mediating cell-cell interactions in organogenesis, and their deregulation has been associated with various cancers, including breast and esophageal cancers. In particular, aberrant epidermal growth factor receptor (EGFR) and HER2 signaling drive disease progression and result in poorer patient outcomes. Nitric oxide (NO) has been proposed as an alternative activator of the HER family and may play a role in this aberrant activation due to its ability to induce s-nitrosation and phosphorylation of the EGFR. This review discusses the potential impact of NO on HER family activation and downstream signaling, along with its role in the efficacy of therapeutics targeting the family.

TMED2 promotes glioma tumorigenesis by being involved in EGFR recycling transport

Aberrant epidermal growth factor receptor (EGFR) signaling is the core signaling commonly activated in glioma. The transmembrane emp24 protein transport domain protein 2 (TMED2) interacts with cargo proteins involved in protein sorting and transport between endoplasmic reticulum (ER) and Golgi apparatus. In this study, we found the correlation between TMED2 with glioma progression and EGFR signaling through database analysis. Moreover, we demonstrated that TMED2 is essential for glioma cell proliferation, migration, and invasion at the cellular levels, as well as tumor formation in mouse models, underscoring its significance in the pathobiology of gliomas. Mechanistically, TMED2 was found to enhance EGFR-AKT signaling by facilitating EGFR recycling, thereby providing the initial evidence of TMED2's involvement in the membrane protein recycling process. In summary, our findings shed light on the roles and underlying mechanisms of TMED2 in the regulation of glioma tumorigenesis and EGFR signaling, suggesting that targeting TMED2 could emerge as a promising therapeutic strategy for gliomas and other tumors associated with aberrant EGFR signaling.

A phase 1, open-label, first-in-human study of TAS2940 in patients with advanced solid tumors.

TPS3165 Background: Aberrant expression and signaling of the ERBB family of receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), has a role in the pathogenesis of solid tumors such as breast cancer (BC), non–small cell lung cancer (NSCLC), and glioblastoma (GBM). Although therapies that target HER2 are effective in early and advanced HER2-overexpressing BC, many patients develop resistance despite tumor dependence on HER2 at the time of progression. Approximately 4% of patients with NSCLC have HER2 mutations, mostly presenting as exon 20 insertions (ex20ins); however, approved HER2/EGFR tyrosine kinase inhibitors (TKIs) have limited efficacy in patients with NSCLC and HER2 ex20ins. Many patients with NSCLC or BC develop brain metastases, and EGFR alterations, including EGFRvIII mutations, are common in GBM. There is therefore a need for a brain-penetrable TKI with activity against tumors harboring HER2/EGFR alterations. TAS2940 is a potent, selective, and orally bioavailable pan-ERBB inhibitor that has shown promising preclinical efficacy against cancers with a variety of HER2/EGFR mutations and amplifications. Further, TAS2940 inhibited tumor growth and induced tumor regression in a dose-dependent manner in nude mice intracranially implanted with NCI-N87, a HER2-overexpressing human gastric cancer cell line. Methods: TAS2940-101 (NCT04982926) is an open-label, phase 1, first-in-human trial to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of TAS2940 in patients with advanced solid tumors and HER2/ EGFR aberrations. Eligible patients are aged ≥18 years, have non-measurable (Part 1) or measurable (Part 1 and 2) disease per RECIST 1.1 or RANO criteria, ECOG performance status 0/1, and adequate organ function. Patients with non-stable brain metastases are excluded. Part 1 (dose escalation) will use a Bayesian optimal interval design with a starting dose of 15 mg/kg orally QD (planned dose levels: 15, 30, 60, 120, 240 and 480 mg). Once the recommended phase 2 dose is determined, Part 2 (dose expansion) will enroll patients with NSCLC (Cohort A), HER2+ BC (Cohort B), recurrent/refractory GBM (Cohort C), or other solid tumors with EGFR/ HER2 aberrations (Cohort D). The primary objectives are the maximum tolerated dose of TAS2940 in Part 1 and antitumor activity in Part 2. Secondary objectives include antitumor activity in Part 1. The safety and PK profile of TAS2940 will be assessed in both parts. Approximately 142 patients will be enrolled, comprising ~42 in Part 1 and ~100 in Part 2. As of January 24, 2023, 15 patients have been enrolled. No dose-limiting toxicities have been reported with dose escalation up to 240 mg QD. Recruitment is ongoing. Clinical trial information: NCT04982926 .

Emerging Therapy for Diabetic Cardiomyopathy: From Molecular Mechanism to Clinical Practice.

Diabetic cardiomyopathy is characterized by abnormal myocardial structure or performance in the absence of coronary artery disease or significant valvular heart disease in patients with diabetes mellitus. The spectrum of diabetic cardiomyopathy ranges from subtle myocardial changes to myocardial fibrosis and diastolic function and finally to symptomatic heart failure. Except for sodium-glucose transport protein 2 inhibitors and possibly bariatric and metabolic surgery, there is currently no specific treatment for this distinct disease entity in patients with diabetes. The molecular mechanism of diabetic cardiomyopathy includes impaired nutrient-sensing signaling, dysregulated autophagy, impaired mitochondrial energetics, altered fuel utilization, oxidative stress and lipid peroxidation, advanced glycation end-products, inflammation, impaired calcium homeostasis, abnormal endothelial function and nitric oxide production, aberrant epidermal growth factor receptor signaling, the activation of the renin-angiotensin-aldosterone system and sympathetic hyperactivity, and extracellular matrix accumulation and fibrosis. Here, we summarize several important emerging treatments for diabetic cardiomyopathy targeting specific molecular mechanisms, with evidence from preclinical studies and clinical trials.

CAR-T cells targeting HLA-G as potent therapeutic strategy for EGFR-mutated and overexpressed oral cancer

Oral squamous cell carcinoma (OSCC) is a common malignancy in the world. Recently, scientists have focused on therapeutic strategies to determine theregulation of tumors and design molecules for specific targets. Some studies have demonstrated the clinical significance of human leukocyte antigen G (HLA-G) in malignancy and NLR family pyrin domain-containing 3 (NLRP3) inflammasome in promoting tumorigenesis in OSCC. This is the first study to investigate whether aberrant epidermal growth factor receptor (EGFR) induces HLA-G expression through NLRP3 inflammasome-mediated IL-1β secretion in OSCC. Our results showed that the upregulation of NLRP3 inflammasome leads to abundant HLA-G in the cytoplasm and cell membrane of FaDu cells. In addition, we also generated anti-HLA-G chimeric antigen receptor (CAR)-T cells and provided evidence for their effects in EGFR-mutated and overexpressed oral cancer. Our results may be integrated with OSCC patient data to translate basic research into clinical significance and may lead to novel EGFR-aberrant OSCC treatment.

The epidermal growth factor receptor in healthy pregnancy and preeclampsia.

The epidermal growth factor receptor (EGFR) is expressed robustly in the placenta, and critical processes of pregnancy such as placental growth and trophoblast fusion are dependent on EGFR function. However, the role that aberrant EGFR signaling might play in the etiology and/or maintenance of preeclampsia (PE) remains largely unexplored. Recently, we have shown that overexpression of EGFR in cultured uterine artery endothelial cells (UAEC), which express little endogenous EGFR, remaps responsiveness away from vascular endothelial growth factor receptor (VEGFR) signaling and toward EGFR, suggesting that endothelial EGFR expression may be kept low to preserve VEGFR control of angiogenesis. Here we will consider the evidence for the possibility that the endothelial dysfunction observed in PE might in some cases result from elevation of endothelial EGFR. During pregnancy, trophoblasts are known to synthesize large amounts of EGFR protein, and the placenta regularly releases syncytiotrophoblast-derived exosomes and microparticles into the maternal circulation. Although there are no reports of elevated EGFR gene expression in preeclamptic endothelial cells, the ongoing shedding of placental vesicles into the vascular system raises the possibility that EGFR-rich vesicles might fuse with endothelium, thereby contributing to the symptoms of PE by interrupting angiogenesis and blocking pregnancy-adapted vasodilatory function.

TAS2940, a novel brain-penetrable pan-ERBB inhibitor, for tumors with HER2 and EGFR aberrations.

Genetic alterations in human epidermal growth factor receptor type 2 (HER2)/epidermal growth factor receptor (EGFR) are commonly associated with breast and lung cancers and glioblastomas. Cancers with avian erythroblastosis oncogene B (ERBB) deregulation are highly metastatic and can cause primary brain tumors. Currently, no pan-ERBB inhibitor with remarkable brain penetration is available. Here, TAS2940, a novel irreversible pan-ERBB inhibitor with improved brain penetrability, was evaluated for its efficacy against several ERBB aberrant cancer models. The selectivity of TAS2940 was evaluated by enzymatic kinase assays. The inhibitory effects of TAS2940 against ERBB genetic alterations were examined using MCF10A cells expressing various HER2 or EGFR mutations and other generic cell lines harboring deregulated ERBB expression. In vivo efficacy of TAS2940 was examined following oral treatment in subcutaneous or intracranial xenograft cancer models. TAS2940 was highly potent against cells harboring HER2/EGFR alterations. TAS2940 could selectively inhibit phosphorylation of targets and the growth of cancer cells with ERBB aberrations in vitro. TAS2940 also inhibited tumor growth in xenograft mouse models with ERBB aberrations: HER2 amplification, HER2/EGFR exon 20 insertions, and EGFR vIII mutation. TAS2940 was effective in the intracranial xenograft models of HER2/EGFR cancers and improved the survival of these mice. TAS2940 has promising therapeutic effects in preclinical study against cancers harboring HER2/EGFR mutations, especially metastatic and primary brain tumors. Our results highlight potential novel strategies against lung cancers with brain metastases harboring HER2/EGFR exon 20 insertions and glioblastomas with EGFR aberrations.

The Role of the Epidermal Growth Factor Receptor in Diabetic Kidney Disease.

The epidermal growth factor receptor (EGFR) is expressed in numerous cell types in the adult mammalian kidney and is activated by a family of EGF-like ligands. EGFR activation has been implicated in a variety of physiologic and pathophysiologic functions. There is increasing evidence that aberrant EGFR activation is a mediator of progressive kidney injury in diabetic kidney disease. This review will highlight recent studies indicating its potential role and mechanisms of injury of both glomerular and tubular cells in development and progression of diabetic kidney disease.

Abstract 2413: αEGFR-E-P125A antibody-endostatin fusion protein reduces vasculogenic mimicry and metastasis by inhibiting FAK, integrin, and EGFR signaling

Abstract Triple-Negative Breast Cancer (TNBC) is an aggressive subtype of breast cancer with high metastatic potential and increased morbidity and mortality. Although expression of, and signaling by the epidermal growth factor receptor (EGFR) is commonly seen in TNBC, anti-EGFR antibodies such as Cetuximab have had limited therapeutic efficacy, used either alone or in combination with chemotherapy. Primary TNBC tumor growth and metastases require supporting vasculature, which develops through a combination of endothelial angiogenesis and vasculogenic mimicry (VM). Our laboratory previously developed a novel targeted therapy, αEGFR-E-P125A, an antibody-endostatin fusion protein, by linking an anti-EGFR antibody targeting domain to a mutated version of the anti-angiogenic protein endostatin (E-P125A). αEGFR-E-P125A delivers a dimeric E-P125A payload which inhibits TNBC angiogenesis and VM in vitro and in vivo, and decreases metastatic tumor growth (lung metastasis) in both the MDA-MB-231-4175 and MDA-MB 468 TNBC xenograft models. Preliminary studies of the mechanism of αEGFR-E-P125A action indicate that αEGFR-E-P125A downregulates VM through combined inhibition of EGFR and integrin signaling. Phospho-array analysis of αEGFR-E-P125A treated MDA-MB-231-4175 cells demonstrated downregulation of phosphorylation of EGFR at Y1069, a site of aberrant EGFR signaling which promotes TNBC motility. The phospho-array also demonstrated inhibition of focal adhesion kinase (FAK) phosphorylation at Y397. FAK signaling occurs downstream of β1 and β3 integrins, and the Y397 site is implicated in the regulation of endothelial and TNBC motility, VM, and metastatic behavior. We specifically inhibited FAK at the Y397 site using a small molecule inhibitor, PF-573228, and demonstrated that FAK inhibition at Y397 alone inhibited the TNBC VM in vitro. shRNA-mediated knockdown of FAK in MDA-MB-231 TNBC cells confirmed that downregulation of FAK inhibited VM formation in vitro. Immunoprecipitation (IP) of EGFR detected the presence of β1 integrin, and IP of β1 integrin detected EGFR in both MDA-MB-231-4175 and MDA-MB-468 TNBC cells treated with αEGFR-E-P125A. αEGFR-E-P125A treatment increased levels of bound β1 integrin following IP of EGFR relative to untreated or Cetuximab treated TNBC cells. These results indicate that αEGFR-E-P125A is binding to both EGFR and β1 integrin simultaneously, suppressing downstream EGFR and integrin signaling. Simultaneous inhibition of EGFR and β1 integrin signaling by αEGFR-E-P125A fusion is a promising approach to inhibition of TNBC growth and metastases. Citation Format: Ankita P. Sankar, Hyun Mi Cho, Hava Gil-Henn, Sundaram Ramakrishnan, Rathin Das, Christian Elledge, Yu Zhang, Seung-Uon Shin, Joseph D. Rosenblatt. αEGFR-E-P125A antibody-endostatin fusion protein reduces vasculogenic mimicry and metastasis by inhibiting FAK, integrin, and EGFR signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2413.

Loss of Tpl2 activates compensatory signaling and resistance to EGFR/MET dual inhibition in v-RAS transduced keratinocytes.

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer in the United States, affecting one million people per year. Patients with aggressive disease have limited treatment options and high mortality, highlighting the need to identify new biomarkers linked to poor clinical outcome. HRAS mutations are found in skin papillomas and cSCCs and increase in frequency when MAP3K family members are inhibited, suggesting a link between blockade of mitogen-activated protein kinase (MAPK) signaling and initiation of RAS-primed cells. Tpl2, a MAP3K gene, can serve as a tumor suppressor gene in cSCC. We have previously shown that upon Tpl2 ablation, mice have heightened sensitivity to aberrant RAS signaling. Tpl2-/- mice display significantly higher numbers of papillomas and cSCCs in two-stage chemical carcinogenesis studies and increased tumorigenicity of keratinocytes expressing oncogenic v-rasHa in nude mouse skin grafts. In part, this is mediated through increased mesenchymal-epithelial transition factor (MET) receptor activity. Epidermal Growth Factor Receptor (EGFR) is reported to be an essential factor for MET-driven carcinogenesis and MET activation may confer resistance to EGFR therapies, suggesting that the concurrent use of both an EGFR inhibitor and a MET inhibitor may show promise in advanced cSCCs. In this study we assessed whether normal or Ras-transformed Tpl2-/- keratinocytes have aberrant EGFR signaling and whether concomitant treatment with EGFR/MET tyrosine kinase inhibitors was more effective than single agents in reducing growth and angiogenic potential of Ras-transformed keratinocytes. Tpl2-/- keratinocytes exhibited increased HER-2 and STAT-3 under basal conditions and elevated p-MET and p-EGFR when transduced with oncogenic RAS. Inhibition of MET by Capmatinib increased p-EGFR in Tpl2-/- keratinocytes and papillomas, and inhibition of EGFR by Gefitinib increased HER2 and HER3 signaling in both genotypes. Treatment of keratinocytes with EGFR and MET inhibitors, in combination, significantly enhanced endothelial tube formation, MMP-9 activity and activation of other RTKs, with more pronounced effects when Tpl2 was ablated. These data indicate that Tpl2 cross-talks with both EGFR and MET signaling pathways. Upon inhibition of EGFR/MET signaling, a myriad of escape mechanisms exists in keratinocytes to overcome targeted drug effects.

Induction of apically mistrafficked epiregulin disrupts epithelial polarity via aberrant EGFR signaling.

In polarized MDCK cells, disruption of the tyrosine-based YXXΦ basolateral trafficking motif (Y156A) in the epidermal growth factor receptor (EGFR) ligand epiregulin (EREG), results in its apical mistrafficking and transformation in vivo. However, the mechanisms underlying these dramatic effects are unknown. Using a doxycycline-inducible system in 3D Matrigel cultures, we now show that induction of Y156A EREG in fully formed MDCK cysts results in direct and complete delivery of mutant EREG to the apical cell surface. Within 3 days of induction, ectopic lumens were detected in mutant, but not wild-type, EREG-expressing cysts. Of note, these structures resembled histological features found in subcutaneous xenografts of mutant EREG-expressing MDCK cells. These ectopic lumens formed de novo rather than budding from the central lumen and depended on metalloprotease-mediated cleavage of EREG and subsequent EGFR activity. Moreover, the most frequent EREG mutation in human cancer (R147stop) resulted in its apical mistrafficking in engineered MDCK cells. Thus, induction of EREG apical mistrafficking is sufficient to disrupt selective aspects of polarity of a preformed polarized epithelium. This article has an associated First Person interview with the first author of the paper.

113P The analysis of EGFR fusions characteristics in Chinese solid tumor patients

Oncogenic mutations in the epidermal growth factor receptor (EGFR) serve as important predictive biomarkers in non-small cell lung cancer (NSCLC). The constitutive activity and sensitivity to EGFR tyrosine kinase inhibitors (TKIs) in lung cancer with small in-frame deletions in exon 19, mutations in exon 21 in the EGFR tyrosine kinase domain had been conferred. Atypical EGFR aberrations, including EGFR kinase domain duplications (KDD) and EGFR fusions (EGFR-RAD51, EGFR-SEPT14, KIF5B-EGFR) had been identified.

The epidermal growth factor receptor axis and kidney fibrosis.

The aim of this study was to summarize recent findings about the role of the epidermal growth factor receptor (EGFR) in acute kidney injury and in progression of chronic kidney injury. There is increasing evidence that EGFR activation occurs as a response to either ischemic or toxic kidney injury and EGFR signalling plays an important role in recovery of epithelial integrity. However, with incomplete recovery or in conditions predisposing to progressive glomerular and tubulointerstitial injury, aberrant persistent EGFR signalling is a causal mediator of progressive fibrotic injury. New studies have implicated activation of HIPPO/YAP signalling as a component of EGFR's actions in the kidney. There is also new evidence for sex disparities in kidney EGFR expression and activation after injury, with a male predominance that is mediated by androgens. There is increasing evidence for an important role for EGFR signalling in mediation of kidney injury, raising the possibility that interruption of the signalling cascade could limit progression of development of progressive kidney fibrosis.

Discovery of amivantamab (JNJ-61186372), a bispecific antibody targeting EGFR and MET

A bispecific antibody (BsAb) targeting the epidermal growth factor receptor (EGFR) and mesenchymal–epithelial transition factor (MET) pathways represents a novel approach to overcome resistance to targeted therapies in patients with non–small cell lung cancer. In this study, we sequentially screened a panel of BsAbs in a combinatorial approach to select the optimal bispecific molecule. The BsAbs were derived from different EGFR and MET parental monoclonal antibodies. Initially, molecules were screened for EGFR and MET binding on tumor cell lines and lack of agonistic activity toward MET. Hits were identified and further screened based on their potential to induce untoward cell proliferation and cross-phosphorylation of EGFR by MET via receptor colocalization in the absence of ligand. After the final step, we selected the EGFR and MET arms for the lead BsAb and added low fucose Fc engineering to generate amivantamab (JNJ-61186372). The crystal structure of the anti-MET Fab of amivantamab bound to MET was solved, and the interaction between the two molecules in atomic details was elucidated. Amivantamab antagonized the hepatocyte growth factor (HGF)-induced signaling by binding to MET Sema domain and thereby blocking HGF β-chain—Sema engagement. The amivantamab EGFR epitope was mapped to EGFR domain III and residues K443, K465, I467, and S468. Furthermore, amivantamab showed superior antitumor activity over small molecule EGFR and MET inhibitors in the HCC827-HGF in vivo model. Based on its unique mode of action, amivantamab may provide benefit to patients with malignancies associated with aberrant EGFR and MET signaling.

Rolling-translated EGFR variants sustain EGFR signaling and promote glioblastoma tumorigenicity.

Aberrant epidermal growth factor receptor (EGFR) activation is observed in over 50% of cases of adult glioblastoma (GBM). Nevertheless, EGFR antibodies are ineffective in clinical GBM treatment, suggesting the existence of redundant EGFR activation mechanisms. Whether circular RNA (circRNA) encodes a protein involved in EGFR-driven GBM remains unclear. We reported an unexpected mechanism in which circular EGFR RNA (circ-EGFR) encodes a novel EGFR variant to sustained EGFR activation. We used RNA-seq, Northern blot, and Sanger sequencing to confirm the existence of circ-EGFR. Antibodies and a liquid chromatograph tandem mass spectrometer were used to identify circ-EGFR protein products. Lentivirus-transfected stable cell lines were used to assess the biological functions of the novel protein in vitro and in vivo. Clinical implications of circ-EGFR were assessed using 97 pathologically diagnosed GBM patient samples. The infinite open reading frame (iORF) in circ-EGFR translated repeating amino acid sequences via rolling translation and programmed -1 ribosomal frameshifting (-1PRF) induced out-of-frame stop codon (OSC), forming a polymetric novel protein-complex, which we termed rolling-translated EGFR (rtEGFR). rtEGFR directly interacted with EGFR, maintained EGFR membrane localization and attenuated EGFR endocytosis and degradation. Importantly, circ-EGFR levels correlated with the EGFR signature and predicted the poor prognosis of GBM patients. Deprivation of rtEGFR in brain tumor-initiating cells (BTICs) attenuated tumorigenicity and enhanced the anti-GBM effect. Our findings identified the endogenous rolling-translated protein and provided strong clinical evidence that targeting rtEGFR could improve the efficiency of EGFR-targeting therapies in GBM.

PD39-06 POOR RESPONSE TO IMMUNOTHERAPY IS ASSOCIATED WITH HIGH EXPRESSION OF A NOVEL EPIDERMAL GROWTH FACTOR RECEPTOR SPLICE VARIANT IN PATIENTS WITH RENAL CELL CARCINOMA

You have accessJournal of UrologyKidney Cancer: Advanced (including Drug Therapy) II (PD39)1 Apr 2020PD39-06 POOR RESPONSE TO IMMUNOTHERAPY IS ASSOCIATED WITH HIGH EXPRESSION OF A NOVEL EPIDERMAL GROWTH FACTOR RECEPTOR SPLICE VARIANT IN PATIENTS WITH RENAL CELL CARCINOMA Ali Hajiran*, Youngchul Kim, Saif Zaman, Thushara Madanyake, Timothy Robinson, Shayan Falasiri, Philippe Spiess, Manish Kohli, Theresa Boyle, James Mulé, Jamie Teer, and Brandon Manley Ali Hajiran*Ali Hajiran* More articles by this author , Youngchul KimYoungchul Kim More articles by this author , Saif ZamanSaif Zaman More articles by this author , Thushara MadanyakeThushara Madanyake More articles by this author , Timothy RobinsonTimothy Robinson More articles by this author , Shayan FalasiriShayan Falasiri More articles by this author , Philippe SpiessPhilippe Spiess More articles by this author , Manish KohliManish Kohli More articles by this author , Theresa BoyleTheresa Boyle More articles by this author , James MuléJames Mulé More articles by this author , Jamie TeerJamie Teer More articles by this author , and Brandon ManleyBrandon Manley More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000918.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Epidermal growth factor receptor (EGFR) is a widely activated oncogene associated with several types of cancer. We identified a novel aberrant EGFR splice variant (EGFR-20-CTF) with specific expression in patients with clear cell renal cell carcinoma (ccRCC). The purpose of this study was to correlate EGFR-20-CTF expression with response to immunotherapy. METHODS: The tumors of 88 patients with ccRCC underwent RNA sequencing and characterization of EGFR-20-CTF. Nineteen patients had received immunotherapy. Patients were divided into 3 tertiles based on levels of EGFR-20-CTF expression. The time from first immunotherapy treatment to death was measured for each patient. Log-rank tests were used to compare survival between groups. Gene set enrichment analysis (GSEA) was also performed. RESULTS: EGFR-20-CTF was identified in 76.1% of ccRCC tumors. Patients with the highest levels of EFR-20-CTF expression had significantly worse survival at 48 months compared to patients with low EGFR-20-CTF (p = 0.036). The average survival in patients with high EGFR-20-CTF expression was < 16 months. GSEA showed that EGFR-20-CTF correlated with a significant decrease in expression of gene sets related to immune response including the HALLMARK inflammatory response, IL-2 signaling, and INF gamma response (all FDR q-val < 0.001). CONCLUSIONS: EGFR-20-CTF occurs frequently in patients with ccRCC and is enriched in patients who had a poor response to immunotherapy. The presence of the EGFR-20-CTF was associated with a global decrease in expression of several gene sets related to immune response, which could account for the decreased response to immunotherapy observed in these patients. This previously unrecognized splice variant presents a possible marker of resistance and will need prospective validation. Source of Funding: Urology Care Foundation Research Scholar Award Program; Society for Urologic Oncology © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e810-e811 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ali Hajiran* More articles by this author Youngchul Kim More articles by this author Saif Zaman More articles by this author Thushara Madanyake More articles by this author Timothy Robinson More articles by this author Shayan Falasiri More articles by this author Philippe Spiess More articles by this author Manish Kohli More articles by this author Theresa Boyle More articles by this author James Mulé More articles by this author Jamie Teer More articles by this author Brandon Manley More articles by this author Expand All Advertisement PDF downloadLoading ...

Rationale for the advancement of PI3K pathway inhibitors for personalized chordoma therapy.

Chordomas are rare and serious tumors with few effective treatments outside of aggressive surgery and radiation. Targeted therapies may present a more effective option for a subset of patients with lesions possessing certain genetic biomarkers. A small molecule inhibitor library was tested in patient-derived UM-Chor1 cells to identify targeted therapies with potential efficacy. Targeted exome sequencing of UM-Chor1 and UM-Chor2 cells was performed to investigate genetic aberrations in relevant pathways. Chordoma cell lines were treated with inhibitors of the phosphotidylinositol 3-kinase (PI3K), epidermal growth factor receptor (EGFR), and cyclin dependent kinase (CDK) pathways, and responses were determined using resazurin cell viability assays, Annexin V apoptosis assays, and western blotting. Pan-PI3K inhibitor BKM120 was also tested in five chordoma xenograft models. Unbiased small molecule profiling nominated PI3K-AKT-mTOR pathway inhibitors as a promising therapy in chordoma, and genetic analyses of UM-Chor1 and UM-Chor2 cell lines revealed aberrations in PTEN, EGFR, and CDKN2A. Treatment of UM-Chor1 and UM-Chor2 with targeted PI3K, EGFR, and CDK inhibitors inhibited growth and proliferation and induced apoptosis more robustly than imatinib, a currently used chordoma therapy. Furthermore, BKM120 significantly inhibited tumor growth in a subset of the xenograft models tested. Targeted therapies, especially those inhibiting PI3K, display promising effects in multiple chordoma cell line and xenograft models. Nevertheless, the limited effects of PI3K, EGFR, and CDK targeting agents in other models reveal the presence of resistance mechanisms, which motivates future research to both identify biomarkers of response and develop combination therapies.

Abstract P6-04-25: Epidermal growth factor receptor as therapeutic target in hormone receptor-positive breast cancer

Abstract Background/Aims: Despite effective therapeutic strategies for treating hormone receptor-positive (HR+) breast cancer, resistance to endocrine therapy that is either de novo or acquired still occurs. We investigated epidermal growth factor receptor (EGFR) as a therapeutic target for overcoming endocrine resistance in HR+ breast cancer models. Methods: Using clinical data from 2,166 patients who had HR+ breast tumors and received tamoxifen, we analyzed survival rates. Levels of mRNA and protein expression were analyzed by real-time PCR and western blotting, respectively. Cell viability was analyzed by MTT assays and anchorage-independent growth by soft agar colony-formation assays. Efficacy of tamoxifen and/or gefitinib was analyzed using orthotopic xenograft mouse models. Results: EGFR expression was significantly associated with more advanced stage and higher grade. EGFR expression was different in luminal A-like (Lum A, 1.3%) versus luminal B-like (Lum B, 11.4%) subtypes. On multivariate analyses for survival Lum B subtype EGFR+ tumors showed a hazard ratio (HR) of 5.22 (95% CI, 1.29-21.15, P = 0.020) for overall survival (OS) and HR of 2.91 (95% CI, 1.35-6.28, P = 0.006) for disease-free survival (DFS). Levels of EGFR inversely correlated with ER-α expression. Basal ER-α level was completely blocked by TGFA or EGF treatment. With TGFA pretreatment, ER+ breast cancer cells were resistant to 4-hydroxytamoxifen (4-OHT). Conversely, downregulation of ER-α by TGFA was reversed by gefitinib with recovered sensitivity to 4-OHT. Tumorigenicity of EGFR and ER+ breast cancer cells was significantly decreased by combined tamoxifen and gefitinib. Conclusion: Aberrant EGFR expression was associated with poor prognosis in ER+ breast cancers, especially the Lum B subtype. Loss of ER by EGFR activation induced tamoxifen resistance. Therefore, EGFR could be a therapeutic target for overcoming recurrence of ER+ breast cancer with high EGFR expression. Citation Format: Yisun Jeong, Soo Youn Bae, Daeun You, Seung Pil Jung, Hee Jun Choi, Isaac Kim, Se Kyung Lee, Jonghan Yu, Seok Won Kim, Jeong Eon Lee, Sangmin Kim, Seok Jin Nam. Epidermal growth factor receptor as therapeutic target in hormone receptor-positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-04-25.