Extracellular Domain Of Epidermal Growth Factor Receptor Research Articles

Epidermal Growth Factor Receptor Targeting in Colorectal Carcinoma: Antibodies and Patient-Derived Organoids as a Smart Model to Study Therapy Resistance.

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. Therefore, the need for new therapeutic strategies is still a challenge. Surgery and chemotherapy represent the first-line interventions; nevertheless, the prognosis for metastatic CRC (mCRC) patients remains unacceptable. An important step towards targeted therapy came from the inhibition of the epidermal growth factor receptor (EGFR) pathway, by the anti-EGFR antibody, Cetuximab, or by specific tyrosine kinase inhibitors (TKI). Cetuximab, a mouse-human chimeric monoclonal antibody (mAb), binds to the extracellular domain of EGFR thus impairing EGFR-mediated signaling and reducing cell proliferation. TKI can affect the EGFR biochemical pathway at different steps along the signaling cascade. Apart from Cetuximab, other anti-EGFR mAbs have been developed, such as Panitumumab. Both antibodies have been approved for the treatment of KRAS-NRAS wild type mCRC, alone or in combination with chemotherapy. These antibodies display strong differences in activating the host immune system against CRC, due to their different immunoglobulin isotypes. Although anti-EGFR antibodies are efficient, drug resistance occurs with high frequency. Resistant tumor cell populations can either already be present before therapy or develop later by biochemical adaptations or new genomic mutations in the EGFR pathway. Numerous efforts have been made to improve the efficacy of the anti-EGFR mAbs or to find new agents that are able to block downstream EGFR signaling cascade molecules. Indeed, we examined the importance of analyzing the anti-EGFR antibody-drug conjugates (ADC) developed to overcome resistance and/or stimulate the tumor host's immunity against CRC growth. Also, patient-derived CRC organoid cultures represent a useful and feasible in vitro model to study tumor behavior and therapy response. Organoids can reflect tumor genetic heterogeneity found in the tissue of origin, representing a unique tool for personalized medicine. Thus, CRC-derived organoid cultures are a smart model for studying the tumor microenvironment and for the preclinical assay of anti-EGFR drugs.

Functionalized siRNA-chitosan nanoformulations promote triple-negative breast cancer cell death via blocking the miRNA-21/AKT/ERK signaling axis: in-silico and in vitro studies

Oncogenic microRNA (miRNA), especially miRNA-21 upregulation in triple-negative breast cancer (TNBC), suggests a new class of therapeutic targets. In this study, we aimed to create GE11 peptide-conjugated small interfering RNA-loaded chitosan nanoparticles (GE11-siRNA-CSNPs) for the targeting of EGFR overexpressed TNBC and selectively inhibit miRNA-21 expression. A variety of in-silico and in vitro cellular and molecular studies were conducted to investigate the binding affinities of specific targets used as well as the anticancer efficacies and mechanisms of GE11-siRNA-CSNPs in TNBC cells. An in-silico assessment reveals a distinct binding affinity of miRNA-21 with siRNA as well as between the extracellular domain of EGFR and synthesized peptides. Notably, the in vitro results showed that GE11-siRNA-CSNPs were revealed to have better cytotoxicity against TNBC cells. It significantly inhibits miRNA-21 expression, cell migration, and colony formation. The results also indicated that GE11-siRNA-CSNPs impeded cell cycle progression. It induces cell death by reducing the expression of the antiapoptotic gene Bcl-2 and increasing the expression of the proapoptotic genes Bax, Caspase 3, and Caspase 9. Additionally, the docking analysis and immunoblot investigations verified that GE1-siRNA-CSNPs, which specifically target TNBC cells and suppress miRNA-21, can prevent the effects of miRNA-21 on the proliferation of TNBC cells via controlling EGFR and subsequently inhibiting the PI3K/AKT and ERK1/2 signaling axis. The GE11-siRNA-CSNPs design, which specifically targets TNBC cells, offers a novel approach for the treatment of breast cancer with improved effectiveness. This study suggests that GE11-siRNA-CSNPs could be a promising candidate for further assessment as an additional strategy in the treatment of TNBC.Graphical

Abstract 2355: SGN-EGFRd2 binding and activity are agnostic to common EGFR extracellular resistance mutations acquired in response to anti-EGFR targeted antibody therapies

Abstract SGN-EGFRd2 is an investigational bispecific antibody comprised of two camelid-derived humanized variable heavy chain only (VHH) domains, one targeting Vγ9Vδ2 (gamma delta) T cells and the other targeting the epidermal growth factor receptor (EGFR). Selective antitumor activity occurs when two conditions are met: 1) the molecule engages both EGFR-expressing tumor cells and gamma delta T cells and 2) butyrophilins, in complex with phosphoantigens (pAgs), are expressed by EGFR-positive tumor cells, resulting in gamma delta T cell directed tumor cell killing by activation, degranulation and secretion of cytolytic molecules. The tumor specific proximity of gamma delta T cells and expression of the butyrophilins/pAgs complex results in the killing of EGFR-expressing tumor cells but not EGFR-expressing normal cells. EGFR is an oncogenic receptor tyrosine kinase and target of several classes of therapeutic modalities, including antibodies. Two antibodies are currently approved for the treatment of EGFR-expressing, KRAS wild-type metastatic colorectal cancer (mCRC): cetuximab (CET) and panitumumab (PAN). Although these anti-EGFR therapies provide significant survival benefits to patients, the duration of response is transient, and most patients progress and develop secondary resistance [1]. One such escape mechanism is the acquisition of mutations in the extracellular domain (ECD) of EGFR, which prevent binding of therapeutic antibodies [2]. Because SGN-EGFRd2 will be tested on patients previously exposed to anti-EGFR therapeutic antibodies, it is paramount to assess its binding to EGFR ECD mutations identified in antibody resistant mCRC patients. EGFR-negative A2058 cells were transduced to express wild type EGFR and a panel of EGFR ECD resistance mutations (N=16). The binding specificity and kinetics of SGN-EGFRd2 were compared to CET and PAN by flow cytometry on engineered cell lines and biolayer interferometry, respectively. Results indicated SGN-EGFRd2 maintained the ability to bind to all tested EGFR ECD mutants, whereas CET and PAN were unable to bind several ECD mutants, as previously described [3,4]. SGN-EGFRd2 binding to EGFR ECD mutant cell lines induced the production of interferon gamma and expression of cell surface CD107a on gamma delta T cells, confirming functional engagement. In contrast to current anti-EGFR therapeutic antibodies, SGN-EGFRd2 binding and activity was unaffected by commonly identified EGFR ECD mutations. These findings highlight SGN-EGFRd2 as a novel molecule targeting wild-type EGFR and common EGFR ECD mutations identified in the mCRC setting. Citation Format: Liem Nguyen, Chun-Shu Wong, Serena Wo, Bryan Grogan, Daniel Diolaiti, Maria Corinna Palanca-Wessels, Astrid Clarke. SGN-EGFRd2 binding and activity are agnostic to common EGFR extracellular resistance mutations acquired in response to anti-EGFR targeted antibody therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2355.

Abstract 1220: Deep mutational scanning of EGFR reveals potential domain-specific TKI sensitivities in lung cancer and glioblastoma

Abstract The epidermal growth factor receptor, EGFR, is frequently activated in lung cancer and glioblastoma by genomic alterations including missense mutations. The different mutation spectra in these diseases are reflected in divergent responses to EGFR inhibition: significant patient benefit in lung cancer, but limited in glioblastoma. Here, we report a comprehensive mutational analysis of EGFR function. We performed saturation mutagenesis of EGFR and assessed function of ~22,500 variants in a human EGFR-dependent lung cancer cell line. This approach revealed enrichment of erlotinib-insensitive variants of known and unknown significance in the dimerization, transmembrane, and kinase domains. Multiple EGFR extracellular domain variants, lacking approved targeted therapies, were sensitive to dacomitinib. Strikingly, at least two glioblastoma patients with G598V dimerization domain mutations showed responses to dacomitinib treatment together with subsequent off-target resistance in one case. In summary, this comprehensive screen reveals novel functional EGFR variants and suggests broader clinical investigation of EGFR inhibition for cancers harboring extracellular domain mutations. Citation Format: Tikvah Hayes, Elisa Aquilanti, Erica Kim, Nicole Persky, Lisa Brenan, Amy Goodale, Ted Sharpe, Doug Alan, Robert Shue, Lior Golomb, Brianna Silverman, Yvonne Li, Lindsay Westlake, Federica Piccioni, Andrew Cherniack, Xiaoping Yang Yang, David Root, J. Kevin Hicks, Andrew Chi, Jorg Dietrich, Daniel Cahill, Cory Johannessen, Tracy Batchelor, Matthew Meyerson. Deep mutational scanning of EGFR reveals potential domain-specific TKI sensitivities in lung cancer and glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1220.

Baseline ctDNA gene alterations as a biomarker of survival after panitumumab and chemotherapy in metastatic colorectal cancer.

Certain genetic alterations and right-sided primary tumor location are associated with resistance to anti-epidermal growth factor (EGFR) treatment in metastatic colorectal cancer (mCRC). The phase 3 PARADIGM trial (n = 802) demonstrated longer overall survival with first-line anti-EGFR (panitumumab) versus antivascular endothelial growth factor (bevacizumab) plus modified FOLFOX6 in patients with RAS wild-type mCRC with left-sided primary tumors. This prespecified exploratory biomarker analysis of PARADIGM (n = 733) evaluated the association between circulating tumor DNA (ctDNA) gene alterations and efficacy outcomes, focusing on a broad panel of gene alterations associated with resistance to EGFR inhibition, including KRAS, NRAS, PTEN and extracellular domain EGFR mutations, HER2 and MET amplifications, and ALK, RET and NTRK1 fusions. Overall survival was prolonged with panitumumab plus modified FOLFOX6 versus bevacizumab plus modified FOLFOX6 in patients with ctDNA that lacked gene alterations in the panel (that is, negative hyperselected; median in the overall population: 40.7 versus 34.4 months; hazard ratio, 0.76; 95% confidence interval, 0.62-0.92) but was similar or inferior with panitumumab in patients with ctDNA that contained any gene alteration in the panel (19.2 versus 22.2 months; hazard ratio, 1.13; 95% confidence interval, 0.83-1.53), regardless of tumor sidedness. Negative hyperselection using ctDNA may guide optimal treatment selection in patients with mCRC. ClinicalTrials.gov registrations: NCT02394834 and NCT02394795 .

Targeted Inhibitors of EGFR: Structure, Biology, Biomarkers, and Clinical Applications.

Members of the EGFR family of tyrosine kinase receptors are major regulators of cellular proliferation, differentiation, and survival. In humans, abnormal activation of EGFR is associated with the development and progression of many cancer types, which makes it an attractive target for molecular-guided therapy. Two classes of EGFR-targeted cancer therapeutics include monoclonal antibodies (mAbs), which bind to the extracellular domain of EGFR, and tyrosine kinase inhibitors (TKIs), which mostly target the intracellular part of EGFR and inhibit its activity in molecular signaling. While EGFR-specific mAbs and three generations of TKIs have demonstrated clinical efficacy in various settings, molecular evolution of tumors leads to apparent and sometimes inevitable resistance to current therapeutics, which highlights the need for deeper research in this field. Here, we tried to provide a comprehensive and systematic overview of the rationale, molecular mechanisms, and clinical significance of the current EGFR-targeting drugs, highlighting potential candidate molecules in development. We summarized the underlying mechanisms of resistance and available personalized predictive approaches that may lead to improved efficacy of EGFR-targeted therapies. We also discuss recent developments and the use of specific therapeutic strategies, such as multi-targeting agents and combination therapies, for overcoming cancer resistance to EGFR-specific drugs.

Hypoxia-induced PLOD2 promotes clear cell renal cell carcinoma progression via modulating EGFR-dependent AKT pathway activation

Clear cell renal cell carcinoma (ccRCC) is a type of kidney cancer that is both common and aggressive, with a rising incidence in recent decades. Hypoxia is a key factor that plays a vital role in the tumorigenesis and metastasis of malignancy. However, the precise mechanisms of hypoxia driving ccRCC progression were not totally uncovered. Our study found that hypoxia level was elevated in ccRCC and might be an independent risk factor of prognosis in ccRCC patients. We identified a key protein PLOD2 was induced under hypoxic conditions and strongly associated with poor prognosis in ccRCC patients. When PLOD2 was depleted, the proliferation and migration of ccRCC cells were reduced in vitro and in vivo, while overexpression of PLOD2 had the opposite effect. Mechanically, the study further revealed that PLOD2 was transcriptionally activated by HIF1A, which binds to a specific promoter region of the PLOD2 gene. PLOD2 was also shown to interact with EGFR, leading to the phosphorylation of the receptor. Furthermore, PLOD2 was responsible for binding to the extracellular domain of EGFR, which ultimately activated the AKT signaling pathway, thus promoting the malignant progression of ccRCC. Treatment with the PLOD2 inhibitor Minoxidil significantly suppressed ccRCC progression by inactivating the EGFR/AKT signaling axis. In summary, the findings of this study shed light on the molecular mechanisms behind PLOD2 expression in ccRCC and suggest that it may serve as a potential predictor and therapeutic target for the clinical prognosis and treatment of ccRCC.

STEM-20. REGULATION OF GLIOMA STEM CELL MAINTENANCE AND THERAPEUTIC RESISTANCE BY EGFR MISSENSE MUTATIONS

Abstract Glioblastoma (GBM) tumors contain a subpopulation of glioma stem cells (GSC) which can escape therapeutic effects through self-renewal and invasion. Epidermal growth factor receptor (EGFR) mutations are the most common alteration in GBM. EGFRvIII (deletion of exons 2-7) is observed in GBM (20-25%) resulting in a constitutively activated EGFR receptor. In addition, extracellular domain missense point mutations, (e.g. G598V, A289V, R108K) are observed in GBM (14.4%). These missense mutations in the EGFR extracellular domain also induces a highly active receptor by enhancing ligand binding. Earlier reports have shown that these EGFR missense point mutations have exhibited therapeutic resistance; however, the molecular mechanism of these missense point mutations in GBM remains unknown. Previous studies in our lab showed that EGFRvIII promotes GSC maintenance and therapeutic resistance via oligodendrocyte transcription factor 2 (OLIG2) signaling. OLIG2 is universally expressed in glioma and essential for reprogramming GBM cells into stem-like tumor cells. Increased OLIG2 expression promotes invasion, growth, proliferation, and survival. Here we report an increase in OLIG2 protein expression in GSCs harboring EGFR-G598V or EGFR-A289V mutations, suggesting these mutations may support stemness properties in GBM tumors. GSC expressing these point mutations display increased self-renewal, growth, and survival. In addition, EGFR-G598V and EGFR-A289V trigger distinct downstream signaling pathways in GSCs to regulate OLIG2 function. Hence, we hypothesize that GBM tumors harboring EGFR missense mutations (G598V, A289V) influence stem cell properties via multiple pathways to evade therapeutic effects and inhibiting these different signaling pathways will decrease therapeutic resistance in GBM. Understanding the mechanism of these EGFR mutations may lead to improved therapeutic strategies for GBM patients.

An EGCG Derivative in Combination with Nimotuzumab for the Treatment of Wild-Type EGFR NSCLC.

Inhibiting the tyrosine kinase activity of epidermal growth factor receptor (EGFR) using small-molecule tyrosine kinase inhibitors (TKIs) or monoclonal antibodies is often ineffective in treating cancers harboring wild-type EGFR. Given the fact that EGFR possesses a kinase-independent pro-survival function, more effective inhibition of EGFR-mediated signals is therefore necessary. In this study, we investigated the effects of using a combination of low-dose nimotuzumab and theasinensin A to evaluate whether the inhibitory effect of nimotuzumab on NCI-H441 cancer cells was enhanced. Here, theasinensin A, a novel epigallocatechin-3-gallate (EGCG) derivative, was identified and its potent anticancer activity against wild-type EGFR NSCLC was demonstrated in vitro; the anticancer activity was induced through degradation of EGFR. Mechanistic studies further revealed that theasinensin A bound directly to the EGFR extracellular domain, which decreased interaction with its ligand EGF in combination with nimotuzumab. Theasinensin A significantly promoted EGFR degradation and repressed downstream survival pathways in combination with nimotuzumab. Meanwhile, treatment with theasinensin A and nimotuzumab prevented xenograft growth, whereas the single agents had limited effect. Thus, the combination therapy of theasinensin A with nimotuzumab is a powerful candidate for treatment of wild-type EGFR cancers.

P10-04: Impact of persistent organic pollutants on EGFR activity in human keratinocytes: Clues for a direct interaction with the EGFR extracellular domain

P10-04: Impact of persistent organic pollutants on EGFR activity in human keratinocytes: Clues for a direct interaction with the EGFR extracellular domain

Addressing Resistance to Therapy in Colorectal Cancer

Addressing Resistance to Therapy in Colorectal Cancer

Degradation of EGFR on lung epithelial cells by neutrophil elastase contributes to the aggravation of pneumococcal pneumonia

Pneumococcus is the main cause of bacterial pneumonia. Pneumococcal infection has been shown to cause elastase, an intracellular host defense factor, to leak from neutrophils. However, when neutrophil elastase (NE) leaks extracellularly, it can degrade host cell surface proteins such as epidermal growth factor receptor (EGFR) and potentially disrupt the alveolar epithelial barrier. In this study, we hypothesized that NE degrades the extracellular domain (ECD) of EGFR in alveolar epithelial cells and inhibits alveolar epithelial repair. Using SDS-PAGE, we showed that NE degraded the recombinant EGFR ECD and its ligand epidermal growth factor, and that the degradation of these proteins was counteracted by NE inhibitors. Furthermore, we confirmed the degradation by NE of EGFR expressed in alveolar epithelial cells invitro. We showed that intracellular uptake of epidermal growth factor and EGFR signaling was downregulated in alveolar epithelial cells exposed to NE and found that cell proliferation was inhibited in these cells These negative effects of NE on cell proliferation were abolished by NE inhibitors. Finally, we confirmed the degradation of EGFR by NE invivo. Fragments of EGFR ECD were detected in bronchoalveolar lavage fluid from pneumococcal pneumonia mice, and the percentage of cells positive for a cell proliferation marker Ki67 in lung tissue was reduced. In contrast, administration of an NE inhibitor decreased EGFR fragments in bronchoalveolar lavage fluid and increased the percentage of Ki67-positive cells. These findings suggest that degradation of EGFR by NE could inhibit the repair of alveolar epithelium and cause severe pneumonia.

Abstract 3396: Discovery of BDTX-1535, a novel 4th generation, irreversible, potent, wild type sparing EGFR MasterKey inhibitor that targets oncogenic kinase domain mutations as well as extracellular domain alterations for the treatment of NSCLC and GBM

Abstract Acquired resistance to 3rd generation EGFR inhibitors used in the treatment of NSCLC is common. While the EGFR C797S substitution is a frequently reported post-osimertinib resistance mutation, real world evidence indicates the emergence of additional EGFR alterations that can drive drug resistance: kinase domain mutations (e.g., S768I), extracellular domain alterations (e.g., EGFRvIII, A289X), and EGFR amplification. Moreover, while osimertinib targets the classical EGFR mutations, primary NSCLC tumors are also driven by other oncogenic kinase domain mutations including G719X, S768I, and L861Q, which confer de novo (intrinsic) resistance to 3rd generation EGFR TKIs. A family of extracellular domain alterations occurs in nearly 50% of GBM patients, and these alterations are clinically resistant to all current generation inhibitors. Real world data in GBM demonstrate these EGFR alterations often co-occur and persist throughout treatment with current standard of care therapy. Of critical importance is the observation that the oncogenic isoform of EGFR in GBM is a covalent homo-dimer which can be formed and paradoxically activated by the binding of reversible 1st generation EGFR inhibitors. There is a significant clinical need to develop a potent CNS penetrant EGFR inhibitor that would target both acquired and intrinsic resistance mutations expressed in NSCLC and co-occurring EGFR alterations in GBM. An effective inhibitor should meet four design principles; 1) potent and selective against a broad family of intracellular, extracellular EGFR oncogenic alterations and amplification, 2) wild type EGFR sparing, 3) irreversible to avoid paradoxical activation, and 4) CNS penetrant. BDTX-1535 is a 4th generation irreversible CNS penetrant EGFR MasterKey inhibitor targeting a family of oncogenic EGFR extracellular domain alterations and amplification in GBM patients and EGFR resistance mutations in NSCLC. BDTX-1535 meets all four criteria for a highly effective EGFR inhibitor and was designed using the MAP Discovery Engine to target the activated conformations used by oncogenic EGFR to drive tumorigenesis. BDTX-1535 achieves potent anti-tumor activity against EGFR alterations and amplification across models including NSCLC and GBM PDX and intracranial tumors. BDTX-1535 is currently in a phase I clinical study in patients with NSCLC and GBM harboring sensitive EGFR alterations (NCT05256290). Citation Format: Matthew O'Connor, Matthew Lucas, Sherri Smith, Anthony Trombino, Sudharshan Eathiraj, Elizabeth Buck. Discovery of BDTX-1535, a novel 4th generation, irreversible, potent, wild type sparing EGFR MasterKey inhibitor that targets oncogenic kinase domain mutations as well as extracellular domain alterations for the treatment of NSCLC and GBM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3396.

Development of Cyclic Peptides Targeting the Epidermal Growth Factor Receptor in Mesenchymal Triple-Negative Breast Cancer Subtype

Triple-negative breast cancer (TNBC) is an aggressive malignancy characterized by the lack of expression of estrogen and progesterone receptors and amplification of human epidermal growth factor receptor 2 (HER2). Being the Epidermal Growth Factor Receptor (EGFR) highly expressed in mesenchymal TNBC and correlated with aggressive growth behavior, it represents an ideal target for anticancer drugs. Here, we have applied the phage display for selecting two highly specific peptide ligands for targeting the EGFR overexpressed in MDA-MB-231 cells, a human TNBC cell line. Molecular docking predicted the peptide-binding affinities and sites in the extracellular domain of EGFR. The binding of the FITC-conjugated peptides to human and murine TNBC cells was validated by flow cytometry. Confocal microscopy confirmed the peptide binding specificity to EGFR-positive MDA-MB-231 tumor xenograft tissues and their co-localization with the membrane EGFR. Further, the peptide stimulation did not affect the cell cycle of TNBC cells, which is of interest for their utility for tumor targeting. Our data indicate that these novel peptides are highly specific ligands for the EGFR overexpressed in TNBC cells, and thus they could be used in conjugation with nanoparticles for tumor-targeted delivery of anticancer drugs.

Integratedin silico–in vitrorational design of oncogenic EGFR-derived specific monoclonal antibody-binding peptide mimotopes

Human epidermal growth factor receptor (EGFR) is strongly associated with malignant proliferation and has been established as an attractive therapeutic target of diverse cancers and used as a significant biomarker for tumor diagnosis. Over the past decades, a variety of monoclonal antibodies (mAbs) have been successfully developed to specifically recognize the third subdomain (TSD) of EGFR extracellular domain. Here, the complex crystal structures of EGFR TSD subdomain with its cognate mAbs were examined and compared systematically, revealing a consistent binding mode shared by these mAbs. The recognition site is located on the [Formula: see text]-sheet surface of TSD ladder architecture, from which several hotspot residues that significantly confer both stability and specificity to the recognition were identified, responsible for about half of the total binding potency of mAbs to TSD subdomain. A number of linear peptide mimotopes were rationally designed to mimic these TSD hotspot residues in different orientations and/or in different head-to-tail manners by using an orthogonal threading-through-strand (OTTS) strategy, which, however, are intrinsically disordered in Free State and thus cannot be maintained in a native hotspot-like conformation. A chemical stapling strategy was employed to constrain the free peptides into a double-stranded conformation by introducing a disulfide bond across two strand arms of the peptide mimotopes. Both empirical scoring and [Formula: see text]fluorescence assay reached an agreement that the stapling can effectively improve the interaction potency of OTTS-designed peptide mimotopes to different mAbs, with binding affinity increase by [Formula: see text]-fold. Conformational analysis revealed that the stapled cyclic peptide mimotopes can spontaneously fold into a double-stranded conformation that well threads through all the hotspot residues on TSD [Formula: see text]-sheet surface and exhibits a consistent binding mode with the TSD hotspot site to mAbs.

NRP1 promotes prostate cancer progression via modulating EGFR-dependent AKT pathway activation

Prostate cancer (PCa) is the most common malignant tumor with a high global incidence in males. The mechanism underlying PCa progression is still not clear. This study observed that NRP1 was highly expressed in PCa and associated with poor prognosis in PCa patients. Functionally, NRP1 depletion attenuated the proliferation and migration ability of PCa cells in vitro and in vivo, while NRP1 overexpression promoted PCa cell proliferation and migration. Moreover, it was observed that NRP1 depletion induced G1 phase arrest in PCa cells. Mechanistically, HIF1α is bound to the specific promoter region of NRP1, thereby regulating its transcriptional activation. Subsequently, NRP1 interacted with EGFR, leading to EGFR phosphorylation. This study also provided evidence that the b1/b2 domain of NRP1 was responsible for the interaction with the extracellular domain of EGFR. Moreover, EGFR mediated NRP1-induced activation of the AKT signaling pathway, which promoted the malignant progression of PCa. In addition, the administration of NRP1 inhibitor EG01377 significantly inactivated the EGFR/AKT signaling axis, thereby suppressing PCa progression. In conclusion, the findings from this study highlighted the molecular mechanism underlying NRP1 expression in PCa and provide a potential predictor and therapeutic target for clinical prognosis and treatment of PCa.

Dual kinase inhibitor for EGFR mutants and ErbB2 limit breast cancer

Mutations in the epidermal growth factor receptor (EGFR) have been found in more than 10% of non-small cell lung cancer (NSCLC) patients in North America. The vast majority of these differences are L858R point mutations in Exon 21. Currently, monoclonal antibodies directed against the extracellular domain of EGFR or small molecule/tyrosine kinase inhibitors (TKI) are the stalwarts of NSCLC therapy. Resistance, however, gradually develops because of the T790 mutation towards first and second generation TKIs. The third generation TKI AZD9291 (Osimertinib) has a high affinity for both activating and the acquired resistant mutation (T790 M) in EGFR, with a low affinity towards wild-type EGFR. Recent research, however, suggests that the EGFR (C797S) mutation in the tyrosine kinase domain is a likely cause of resistance to AZD9291. Another significant transformation mechanism associated with this resistance is erbB2 amplification. Our laboratory has developed a small kinase inhibitor, ER121 (MW: ∼500), that inhibits the erbB2/HER2 tyrosine kinases in addition to the EGFR C797S mutations. We have identified a TKI, ER121 targeting the mutant EGFR(T790 M). Using in vitro and in vivo models, examined the efficacy of ER121 on mutant EGFR cell lines. This has enabled us to establish that ER121 is well tolerated when administered orally and produces significant inhibitory activity against human cancers generated by mutant EGFR and amplified ErbB2.

Panitumumab plus trifluridine/tipiracil as third-line anti-EGFR rechallenge therapy in chemo-refractory RAS WT metastatic colorectal cancer: The VELO randomized phase II clinical trial.

129 Background: Rechallenge therapy with epidermal growth factor receptor (EGFR) inhibitors in chemo-refractory metastatic colorectal cancer (mCRC) is an emerging therapeutic approach. Trifluridine-tipiracil is approved for treatment of chemo-refractory mCRC patients. Methods: Chemo-refractory RAS WT mCRC patients, that had a major response (partial or complete response) to first-line chemotherapy plus an anti-EGFR monoclonal antibody and had an-anti-EGFR drug-free interval during second-line therapy of four or more months were randomized in a phase II trial to assess the addition of the anti-EGFR monoclonal antibody panitumumab to trifluridine-tipiracil as third-line rechallenge therapy. The primary endpoint was progression free survival (PFS). Baseline plasma was analyzed for circulating free tumor (ct) DNA by using Biocartis Idylla platform to detect mutations in KRAS, NRAS, BRAF ( V600E) and EGFRextracellular domain ( S492R). In 24 patients with baseline RAS/BRAF wild type (WT) ctDNA, Foundation One liquid CDx (324 gene profiling) was also performed before treatment and at disease progression. Results: 62 patients were treated with trifluridine-tipiracil (31 patients, arm A) or with trifluridine-tipiracil plus panitumumab (31 patients, arm B). As of September 16, 2022, 1 patient in arm A and 2 patients in arm B were on treatment. The primary endpoint was met. Median PFS (mPFS) was 4 months in arm B versus 2.5 months in arm A [hazard ratio (HR): 0.48; 95% CI 0.28-0.82; P = 0.007]. Baseline plasma RAS/BRAF WT ctDNA was found in 23/31 patients in Arm A and in 26/31 patients in Arm B. In this group, mPFS was 4.5 months in Arm B versus 2.6 months in Arm A (HR: 0.48; 95% CI 0.26-0.89; P = 0.019). Disease control (major responses plus stable disease) was higher for patients in Arm B compared to Arm A (81% versus 48%), whereas disease progression was the best response in 19% versus 52% patients, respectively. PFS rates at 6 and 12 months were 38.5% and 15.4% in arm B versus 13% and 0% in arm A. At disease progression, Foundation One liquid CDx detected several mutations within the EGFR pathway, which could correlate with cancer cell resistance to panitumumab. Conclusions: This is the first prospective randomized trial which evaluated anti-EGFR monoclonal antibody (panitumumab) in addition to standard of care (trifluridine-tipiracil) as third-line rechallenge therapy in chemo-refractory RASWT mCRC patients. Baseline liquid biopsy allows selection of RAS/BRAF WT ctDNA patients who could have a relevant clinical benefit. Clinical trial information: NCT05468892 .

Binding sites in the epidermal growth factor receptor are responsible for bisphenol S effects on trophoblast cell invasion

Bisphenol S (BPS) is an endocrine disrupting chemical and the second most abundant bisphenol detected in humans. We have recently demonstrated that in utero exposure to BPS reduces human placenta cell fusion by interfering with epidermal growth factor (EGF)-dependent EGF receptor (EGFR) activation. Our previous work suggests that this occurs via binding of BPS to the extracellular domain of EGFR. However, whether BPS directly binds to EGFR has not been confirmed. We evaluated the binding ability of BPA, BPF and BPS to EGFR to determine whether EGFR binding is a unique attribute of BPS. To test these hypotheses, we first exposed HTR-8/SVneo cells to BPS, BPA, or BPF, with or without EGF. When co-exposed to EGF, BPS, but not BPA nor BPF, reduced EGFR phosphorylation by ∼60%, demonstrating that only BPS can interfere with EGF-dependent EGFR activation. As this indicates that BPS binding to the extracellular domain is responsible for its effect, we performed a computational search for putative binding sites on the EGFR extracellular domain, and performed ligand docking of BPS, BPA, and BPF at these sites. We identified three sites where polar interactions between positively charged residues and the sulfonyl group of BPS could lead binding selectivity over BPA and BPF. To test whether EGFR mutations at the predicted BPS binding sites (Arg255, Lys454, and Arg297) could prevent BPS's interference on EGFR activation, mutations for each EGFR target amino acids (R255A, R297A, and K454A) were introduced. For variants with R297A or K454A mutations, BPS did not affect EGF-mediated EGFR phosphorylation or EGFR-mediated cell invasion, suggesting that these residues are needed for the BPS antagonism effect on EGFR. In conclusion, BPS, but not BPA or BPF, interferes with EGFR-mediated trophoblast cell functions through binding at Arg297 and Lys454 amino acid residues in the extracellular domain of EGFR.

CircIFNGR2 enhances proliferation and migration of CRC and induces cetuximab resistance by indirectly targeting KRAS via sponging to MiR-30b

Currently the clinical efficacy of colorectal cancer (CRC) which is the most common malignant tumors over the world has not reached an ideal level. Cetuximab, the monoclonal antibody targeting the extracellular domain of EGFR, has shown its great efficacy in the promotion of apoptosis and the inhibition of tumor cells-like characteristics in numerous cancers. However certain KRAS wild-type CRC patients unexpectedly show cetuximab resistance and the specific mechanism remains unclear. Circular RNAs (circRNAs) as the promising novel type of biomarkers in the cancer diagnosis and therapy, have been reported to be related with the drug resistance. In this study, with wondering the mechanism of cetuximab resistance in KRAS wild-type CRC patients, we evaluate the impact of circIFNGR2 on CRC and detect the association among circIFNGR2, miR-30b and KRAS via various experiments such as RT-qPCR, immunohistochemistry, luciferase assays, cell functional experiments and xenograft model. We conclude that circIFNGR2 induces cetuximab resistance in colorectal cancer cells by indirectly regulating target gene KRAS by sponging miR-30b at the post-transcriptional level. It is thus suggested that inhibition of circIFNGR2 can be a promising therapeutic strategy for malignant CRC patients with cetuximab resistance.