Epidermal Growth Factor Receptor Affinity Research Articles

Enhanced amphiregulin exposure promotes modulation of the high grade serous ovarian cancer tumor immune microenvironment

High grade serous ovarian cancer (HGSOC) is a lethal gynecologic malignancy in which chemoresistant recurrence rates remain high. Furthermore, HGSOC patients have demonstrated overall low response rates to clinically available immunotherapies. Amphiregulin (AREG), a low affinity epidermal growth factor receptor ligand is known to be significantly upregulated in HGSOC patient tumors following neoadjuvant chemotherapy exposure. While much is known about AREG’s role in oncogenesis and classical immunity, it is function in tumor immunology has been comparatively understudied. Therefore, the objective of this present study was to elucidate how increased AREG exposure impacts the ovarian tumor immune microenvironment (OTIME). Using NanoString IO 360 and protein analysis, it was revealed that treatment with recombinant AREG led to prominent upregulation of genes associated with ovarian pathogenesis and immune evasion (CXCL8, CXCL1, CXCL2) along with increased STAT3 activation in HGSOC cells. In vitro co-culture assays consisting of HGSOC cells and peripheral blood mononuclear cells (PBMCs) stimulated with recombinant AREG (rAREG) led to significantly enhanced tumor cell viability. Moreover, PBMCs stimulated with rAREG exhibited significantly lower levels of IFNy and IL-2. In vivo rAREG treatment promoted significant reductions in circulating levels of IL-2 and IL-5. Intratumoral analysis of rAREG treated mice revealed a significant reduction in CD8+ T cells coupled with an upregulation of PD-L1. Finally, combinatorial treatment with an AREG neutralizing antibody and carboplatin led to a synergistic reduction of cell viability in HGSOC cell lines OVCAR8 and PEA2. Overall, this study demonstrates AREG’s ability to modulate cytotoxic responses within the OTIME and highlights its role as a novel HGSOC immune target.

Design and Evaluation of a Humanized Anti-EGFR huscFv Antibody Fragment in Combination With Metformin in A549 Cells In Vitro.

The epidermal growth factor receptor (EGFR) is over-expressed in several types of cancer, and monoclonal antibody therapy has been the strategy that has shown the best results. This study focused on the construction of a humanized single chain antibody (huscFv) directed against EGFR (HER1). The CDR grafting method was used to incorporate murine complementarity determining regions (CDRs) of cetuximab into human sequences. A dot blot assay was used to examine the affinity of the huscFv secreted by HEK293T for EGFR. The inhibitory effect on the viability of A549 cells was evaluated using the WST-1 assay. The incorporation of murine CDRs of cetuximab into human sequences increased the degree of humanness by 16.4%. The increase in the humanization of scFv did not affect the affinity for EGFR. Metformin had a dose-dependent effect, with an IC50 of 46 mM, and in combination with huscFv, the cell viability decreased by 45% compared to the 15% demonstrated by huscFv alone. The CDR grafting technique is efficient for the humanization of scFv, maintaining its affinity for EGFR and demonstrating its inhibitory effect when combined with metformin in A549 cells.

Abstract 5083: Discovery of an asymmetric IgG-like bispecific ADC targeting EGFR/HER3

Abstract Background: The epidermal growth factor receptor (EGFR) family, consisting of EGFR, HER2, HER3, and HER4, plays a critical role in tumorigenesis and tumor progression. Inhibition of ERBBs using either monoclonal antibodies (mAb) or small-molecule tyrosine kinase inhibitors have been approved for use for the treatment of various types of cancers. Despite relative success, many patients acquire resistance to long-term benefit due to alternative compensatory signaling pathways. Accordingly, activating mutations or overexpression of HER3 has been reported in many cancers, such as breast, ovarian, lung, colorectal, melanoma, head and neck, cervical and prostate cancers. Here, we report the discovery of a humanized anti-EGFR x HER3 IgG-like bispecific antibody-drug conjugate (ADC). The ADC takes a asymmetric 1+1 form through HC-HC and HC-LC charge-based heterodimerization, which is then conjugated to a topoisomerase 1 inhibitor (TOP1i) payload via a cleavable linker. The affinity of EGFR and HER3 was optimized to improve the therapeutical window, and has shown potent anti-tumor efficacy in various tumor models with limited toxicity supporting further development in clinic. Methods: An anti-EGFR x HER3 bispecific ADC (PM1300) was generated by introducing unique mutations to the CH1-CL domains of each binding arm to avoid HC-LC mispairing. KIH mutations were also introduced to each CH3 domain to support HC/HC heterodimerization and generate an IgG-like bispecific with one arm binding to EGFR and the other to HER3. TOP1i payload was conjugated to the IgG-like bispecific by the endogenous cysteine residues at DAR 8 via a clearable linker. Results: Through affinity optimization, PM300 was found to preferentially bind to EGFR/HER3 double-positive cells rather than EGFR single-positive cells. PM1300 showed significantly increased internalization and anti-proliferation activity against EGFR/HER3 double-positive cells, with limited activity towards single positive-cells. PM1300 used an optimized linker for better payload release and serum stability. PM1300 induced a potent anti-tumor efficacy in various CDX models representing different EGFR and HER3 expressing levels and mutations. Importantly, PM1300 exhibited a good safety profile in NHP consistent with the optimal affinity for EGFR and HER3. These results demonstrate that PM1300 has a promising efficacy/safety therapeutical window in preclinical models supporting further development in the clinic. Conclusion: A bispecific ADC targeting EGFR x HER3 was discovered, named PM1300, which has an asymmetric 1+1 IgG-like structure and optimized affinity. This allows for preferential binding to EGFR/HER3 double-positive cancer cells, rather than EGFR single-positive cells. This may significantly contribute to minimizing safety risk that is common for EGFR-targeting agents. Citation Format: Liandi Chen, Shaogang Peng, Chao Wang, Xiaoniu Miao, Yao Yan, Jun Xing, Weifeng Huang, Andy Tsun, Yingda Xu, Xiaolin Liu, Yi Luo. Discovery of an asymmetric IgG-like bispecific ADC targeting EGFR/HER3 [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 5083.

Abstract 6364: The bispecific antibody KA-3006 against both EGFR and MET surpasses amivantamab in efficacy

Abstract A bispecific antibody (BsAb) like amivantamab, which targets both the epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) by blocking downstream pathways, has been proven to overcome resistance to targeted therapies, including EGFR inhibitors, in patients with various cancers. In this study, we developed a bispecific antibody, KA-3006, targeting both EGFR and MET using our common light chain antibody discovery platform. KA-3006 has a regular antibody structure with an identical light chain, developed through knob-into-hole technology. It exhibits high affinity for MET and relatively low affinity for EGFR. KA-3006 specifically blocks both the binding of EGF to EGFR and HGF to MET with higher efficiency than amivantamab, resulting in the blockade of downstream signaling from EGFR and MET. In comparison to amivantamab, KA-3006 demonstrates a faster internalization rate when binding to the surface of tumor cells expressing both EGFR and MET. KA-3006 showed superior antitumor activity over amivantamab in the HCC827-HGF in vivo model. Additionally, KA-3006 has a half-life of more than five days in the blood of Balb/c mice. Finally, we assessed the developability of this BsAb with different treatments such as high concentration, low pH, repeated freezing and thawing, and high temperature, and KA-3006 showed neither aggregation nor degradation. In conclusion, the BsAb KA-3006, developed with our common light chain antibody discovery platform, is a promising pre-clinical candidate drug for the treatment of various solid cancers with overactivated EGFR and MET signaling, and it holds potential for developing ADCs targeting both EGFR and MET. Citation Format: Guojin Wu, Jiabei Liang, Hao Peng, Feng Hao, Tongtong Liu, Jinying Ning. The bispecific antibody KA-3006 against both EGFR and MET surpasses amivantamab in efficacy [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 6364.

Abstract 1341: SM2235: A bispecific EGFR x CD16A innate immune cell engager for enhanced treatment of EGFR-expressing solid tumors, regardless of RAS mutation status

Abstract Background: Monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR) are frontline therapies for numerous EGFR-dependent epithelial tumors. However, their efficacy faces challenges due to on-target skin toxicity and intrinsic or acquired resistance. Within the tumor microenvironment, innate immune cells, including macrophages and natural killer (NK) cells, play a significant role but are hindered by the lack of specific cancer cell targeting and a suppressive microenvironment. To enhance innate immune cell cytotoxicity, we have developed SM2235, a humanized tetravalent bispecific VHH antibody. SM2235 partially blocks EGFR and EGF interaction while conditionally activating innate immune cells through CD16A upon engagement with cancer cells. Methods: SM2235 was engineered by combining a partially blocking EGFR single-domain antibody with a high-affinity CD16A-activating single-domain antibody on an inactivated human IgG1 Fc backbone. The binding affinity and specificity were confirmed using bio-layer interferometry and ELISA with recombinant proteins, followed by flow cytometry with EGFR+ human cancer cell lines and CD16A+ primary NK cells. SM2235's efficacy in blocking EGFR-EGF interaction and downstream signaling was assessed through competitive ELISA and proliferation assays in both EGFR-dependent and independent cancer cell lines. Its ability to induce target-dependent NK cell and macrophage activation was evaluated through activation markers as well as cytotoxicity and phagocytosis assays. In vivo efficacy of SM2235 against EGFR+ human tumors was measured using xenograft assays in NSG mice, covering cetuximab-sensitive and resistant cancer cell lines. Preliminary pharmacokinetics and safety studies were conducted in cynomolgus monkeys. Results: SM2235 exhibits sub-nanomolar affinity for EGFR+ human cancer cell lines and CD16A+ primary human NK cells. It partially inhibits EGFR-dependent cancer cell proliferation. Compared to cetuximab, SM2235 significantly enhances target-dependent CD16A-mediated NK cell and macrophage activation and cytotoxicity against EGFR+ cancer cells in ADCC and ADCP assays in vitro. SM2235 effectively inhibits EGFR+ xenograft tumors in vivo, irrespective of KRAS mutation status. In cynomolgus monkeys, SM2235 demonstrates excellent tolerance with a 20-hour serum half-life of approximately 20 hours and no dose-dependent skin toxicity. Conclusions: Preclinical characterization of SM2235 shows promising in vivo efficacy against EGFR+ human cancers, regardless of KRAS mutation, with a favorable safety profile marked by minimal skin toxicity. Citation Format: Huiqin Geng, Wenjing Song, Xiaodan Liu, Shihao Lu, Hong Zhou, Simin Yang, Siyao Xie, Yi Wei, Xing Zhang, Sheila Zhou, Yanbin Liang. SM2235: A bispecific EGFR x CD16A innate immune cell engager for enhanced treatment of EGFR-expressing solid tumors, regardless of RAS mutation status [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 1341.

Identification of potential therapeutic dual inhibitors of EGFR/HER2 in breast cancer

Breast cancer (BC) is the leading cause of death among women worldwide. According to the Breast Cancer Research Foundation (BCRF), 25% of all cases of BC are positive for human epidermal growth factor receptor 2 (HER2), which is the most aggressive phenotype among the five BC subtypes. Previous studies have reported that the epidermal growth factor receptor (EGFR) is also overexpressed in HER2-positive BC, which elevates disease severity. Based on these findings, the present study aimed to identify dual inhibitors of EGFR and HER2 by employing chemometric modelling techniques. A dataset of chemical molecules with affinity for both EGFR and HER2 was prepared by literature review. The dataset was split into training and test sets based on the inhibitory concentration (IC50) for EGFR and HER2. The training set was used to generate two pharmacophore models, one each for EGFR (n = 30, R2 value = 0.82 with RMSD = 1.4, Δ cost = 151.84, and configuration cost = 20.3) and HER2 (n = 30, R2 value = 0.84 with RMSD = 1.0, Δ cost = 68.47, and configuration cost = 22.2). The developed models were validated using the test set (n = 214 and 201, andR2pred = 0.73 and 0.70, for EGFR and HER2, respectively), decoy set (decoys = 104, actives = 18), and an external dataset (n = 20). The robustness of the models was validated using Fischer's randomization method (at 95% confidence) and applicability domain analysis. The validated models for EGFR and HER2 were used to screen the Asinex library (n = 575,302) for identifying consensus hits against both targets. Molecules with predicted IC50 < 20 nM were subsequently screened, and their toxicity profiles were evaluated using ProTox II. The interactions, ligand efficiency, and binding affinities of the selected compounds were assessed from the docking scores and molecular mechanics with generalized Born and surface area solvation (MMGBSA) energy. Hit selection against EGFR and HER2 was finally achieved by molecular dynamics simulations using the OPLS4 force field in Desmond. The identified hit can serve as a reference for developing dual inhibitors of EGFR and HER2 in future.

Synthesis and evaluation of a rociletinib analog as prospective imaging double mutation L858R/T790M in non-small cell lung cancer

Context: Imaging the mutation status of non-small cell lung cancer (NSCLC) using radiolabeled tyrosine kinase inhibitor (TKI) analogs has garnered interest due to their unique interactions with the target epidermal growth factor receptor (EGFR). Rociletinib is a third-generation TKI that selectively inhibits the activated EGFR L858R/T790M mutations while sparing the wild-type EGFR. Aims: To synthesize a rociletinib analog for radioiodination purposes and evaluate its affinity for EGFR L858R/T790M using molecular docking and in vitro cytotoxicity assay. Methods: The rociletinib analog, N-{3-[(4-{[4-(4-acetylpiperazin-1-yl)-2-methoxyphenyl]amino}-5-(trifluoromethyl)pyrimidine-2-yl)amino] -5-iodophenyl} acrylamide (I-RMFZ), was produced by adding iodine into the diaminophenyl group and changing the position of the trifluoromethyl group. A simulation of molecular docking was conducted using the AutoDock Vina software suite. IC50 of I-RMFZ was determined using a cell cytotoxicity assay. Results: I-RMFZ was successfully synthesized through multistep reactions. Molecular docking revealed that I-RMFZ interacts with the EGFR L858R/T790M mutation. Cytotoxicity assay demonstrated that I-RMFZ had a high selectivity towards EGFR L858R/T779M mutation. Conclusions: I-RMFZ is notable for radioiodination and is anticipated to be comparable with in vivo features of rociletinib. Thus, I-RMFZ can potentially be developed as an imaging agent for NSCLC through preclinical assay.

AGCM-22, a novel cetuximab-based EGFR-targeting antibody-drug-conjugate with highly selective anti-glioblastoma efficacy

The epidermal growth factor receptor (EGFR) has received significant attention as a potential target for glioblastoma (GBM) therapeutics in the past two decades. However, although cetuximab, an antibody that specifically targets EGFR, exhibits a high affinity for EGFR, it has not yet been applied in the treatment of GBM. Antibody-drug conjugates (ADCs) utilize tumor-targeting antibodies for the selective delivery of cytotoxic drugs, resulting in improved efficacy compared to conventional chemotherapy drugs. However, the effectiveness of cetuximab as a targeted antibody for ADCs in the treatment of GBM remains uncertain. In this study, we synthesized AGCM-22, an EGFR-targeted ADC derived from cetuximab, by conjugating it with the tubulin inhibitor monomethyl auristatin E (MMAE) using our Valine-Alanine Cathepsin B cleavable linker. In vitro experiments demonstrated that AGCM-22 effectively inhibited GBM cell proliferation through increased levels of apoptosis and autophagy-related cell death, whereas cetuximab alone had no anti-GBM effects. Additionally, both mouse and human orthotopic tumor models exhibited the selective tumor-targeting efficacy of AGCM-22, along with favorable metabolic properties and superior anti-GBM activity compared to temozolomide (TMZ). In summary, this study presents a novel ADC for GBM therapy that utilizes cetuximab as the tumor-targeting antibody, resulting in effective delivery of the cytotoxic drug payload.

Identification of Potential Phytochemical Inhibitors From Conium maculatum Targeting the Epidermal Growth Factor Receptor in Metastatic Colorectal Cancer via Molecular Docking Analysis.

Background Metastatic colorectal cancer (mCRC) continues to rank as the second deadliest cancer on the global scale.CRC diagnosed at metastatic (stage IV)makes treatment strategies more challenging. Even though there are numerous therapeutic options available, the side effects of these treatments threaten the human health.Therefore, we are in the phase of searching new molecules that are less harmful and cost-effective. The common source of many pharmaceutical medications is plants. This study focuses on virtually screening phytochemicals from Conium maculatum as potential inhibitors of the epidermal growth factor receptor (EGFR), a crucial target in cancer therapy. Methods and materials C. maculatum was selected due to its phytochemicals and prior indications of its anticancer properties. In silico investigations encompass druglikeness screening, pharmacokinetics assessment, molecular docking, toxicity prediction, molecular target screening, and molecular dynamics simulations. A comprehensive analysis led to the identification of promising lead compounds. Results A total of 25 compounds exhibited favorable pharmacokinetic and drug-like characteristics. Among them, 12 compounds displayed a high affinity for EGFR as determined by molecular docking experiments. Further safety assessment using ProTox-II revealed that seven compounds had no anticipated toxicity, affirming their safety profiles. Conclusion These findings collectively predicted the efficacy of seven phytochemicals from C.maculatum as EGFR inhibitors in mCRC. Further experimental investigations and optimization of the identified leads were needed to validate the efficacy and safety of identified lead compounds and explore their therapeutic potential in CRC.

Molecular Docking Studies and ADME Predictions on Synthesized Chalcone Compounds Targeting EGFR

In the present study, new chalcone derivatives (5a–5f) obtained from the condensation reaction of cuminaldehyde and acetophenone compounds containing different substituents were reported. Chemical characterization (1HNMR and 13CNMR analysis) and molecular docking studies of the synthesized compounds were performed against the epidermal growth factor receptor (EGFR) and reference drug (metachalcone). Erlotinib was used as the reference ligand. Compound 5 (-7.6 kcal mol-1), compound 6 (-7.38 kcal mol-1), and compound 7 (-7.44 kcal mol-1) were found to be the strongest inhibitors of EGFR when compared to Erlotinib (-7.0 kcal mol-1). In addition, an ADME estimation was made. It was determined that the synthesized compounds could be potent EGFR inhibitors compared to Erlotinib. Compounds 5-7 and the target protein showed a better binding affinity for EGFR than the reference compound (Erlotinib). The synthesized compounds can be potent inhibitors for EGFR-mutated cancers.

Abstract 2009: Gemcitabine-loaded EGFR aptamer for targeted therapy of lung cancer

Abstract Lung cancer is the leading cause of cancer-related death in the world and non-small cell lung cancer (NSCLC) is the most common types of the lung cancer. Epidermal growth factor receptor (EGFR) is an attractive therapeutic target due to its high expression in NSCLC. Gemcitabine (Gem) has shown antitumor activity against many kinds of solid tumors, including NSCLC. Aptamers emerged as promising drug delivery vehicles because of their high binding affinity for the target molecules. The objective of this study was to develop the aptamer-drug conjugates using the EGFR-specific aptamer. EGFR aptamers selected by the SELEX process and gemcitabine was internally incorporated into the EGFR aptamer. In vitro binding affinity of EGFR and Gem-loaded EGFR aptamer was evaluated on EGFR-positive A549, H460, H1299 cell lines, as well as EGFR-negative H522 cells using confocal microscopy. To determine whether the Gem-loaded EGFR aptamer was effectively internalized, Z-stack images were acquired after 1 hr incubation of Cy5-conjugated EGFR aptamer at 37°C. The ex vivo biodistribution of Cy7-conjugated EGFR aptamer was investigated in NSCLC xenograft nude mice. To confirm the antiproliferative effects of Gem-loaded EGFR aptamer, the MTT cell proliferation assay was carried out in NSCLC cells. In the confocal image of EGFR-positive cells, Gem-loaded EGFR aptamers were selectively bound to the cell surface, while no aptamer binding was observed in H522 cells. Z-stack imaging showed that internalized Gem-loaded EGFR aptamer accumulated in EGFR-positive cells. The ex vivo biodistribution data showed that the Gem-loaded EGFR aptamer exhibited higher binding in EGFR-positive A549 tumors than scramble EGFR aptamer. A549 cells showed significant reduction in proliferation following treatment with Gem-loaded EGFR aptamer. Our results indicated that Gem-loaded EGFR aptamer has a potential therapeutic agent in EGFR-positive NSCLC therapy. Citation Format: Jun Young Park, Ye Lim Cho, Ju Ri Chae, Won Jun Kang. Gemcitabine-loaded EGFR aptamer for targeted therapy of lung cancer [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 2009.

Enzyme-Instructed Peptide Assembly Favored by Preorganization for Cancer Cell Membrane Engineering.

Innovative methods for engineering cancer cell membranes promise to manipulate cell-cell interactions and boost cell-based cancer therapeutics. Here, we illustrate an in situ approach to selectively modify cancer cell membranes by employing an enzyme-instructed peptide self-assembly (EISA) strategy. Using three phosphopeptides (pY1, pY2, and pY3) targeting the membrane-bound epidermal growth factor receptor (EGFR) and differing in just one phosphorylated tyrosine, we reveal that site-specific phosphorylation patterns in pY1, pY2, and pY3 can distinctly command their preorganization levels, self-assembling kinetics, and spatial distributions of the resultant peptide assemblies in cellulo. Overall, pY1 is the most capable of producing preorganized assemblies and shows the fastest dephosphorylation reaction in the presence of alkaline phosphatase (ALP), as well as the highest binding affinity for EGFR after dephosphorylation. Consequently, pY1 exhibits the greatest capacity to construct stable peptide assemblies on cancer cell membranes with the assistance of both ALP and EGFR. We further use peptide-protein and peptide-peptide co-assembly strategies to apply two types of antigens, namely ovalbumin (OVA) protein and dinitrophenyl (DNP) hapten respectively, on cancer cell membranes. This study demonstrates a very useful technique for the in situ construction of membrane-bound peptide assemblies around cancer cells and implies a versatile strategy to artificially enrich cancer cell membrane components for potential cancer immunotherapy.

Affilin-based retargeting of adenoviral vectors to the epidermal growth factor receptor

IntroductionTreatment of head and neck squamous cell carcinomas (HNSCC) by oncolytic adenoviral vectors holds promise as an efficient anti-cancer therapy. The epidermal growth factor receptor (EGFR) represents an attractive target receptor since it is frequently overexpressed in many types of HNSCC. MethodsTo achieve EGFR-specific targeting by human adenovirus type 5 (HAdV-5) based vectors, the EGFR affinity ligand Affilin was covalently attached in a position specific manner either to the fiber or the hexon protein of the vector capsid. In vitro and in vivo studies investigated EGFR-specific cancer cell transduction, susceptibility to natural sequestration mechanisms, pharmacokinetics and biodistribution profiles of Affilin-decorated vectors. ResultsAffilin-decorated vectors showed strongly enhanced and EGFR-specific cancer cell transduction in vitro and less susceptibility to known sequestration mechanisms of HAdV-5 particles. However, in vivo neither systemic nor intratumoral vector administration resulted in an improved transduction of EGFR-positive tumors. Comprehensive analyses indicated hampered EGFR-targeting by Affilin-decorated vectors was caused by rapid vector particle consumption due to binding to the murine EGFR, insufficient tumor vascularization and poor target accessibility for Affilin in the solid tumor caused by a pronounced tumor stroma. ConclusionIn vitro studies yielded proof-of-concept results demonstrating that covalent attachment of a receptor-specific Affilin to the adenoviral capsid provides an effective and versatile tool to address cancer-specific target receptors by adenoviral vectors. Regarding EGFR as the vector target, off-target tissue transduction and low receptor accessibility within the tumor tissue prevented efficient tumor transduction by Affilin-decorated vectors, rendering EGFR a difficult-to-target receptor for adenoviral vectors.

Discovery of Hyperstable Noncanonical Plant-Derived Epidermal Growth Factor Receptor Agonist and Analogs.

Here, we report the discovery of the first plant-derived and noncanonical epidermal growth factor receptor (EGFR) agonist, the 36-residue bleogen pB1 from Pereskia bleo of the Cactaceae family. We show that bleogen pB1 is a low-affinity EGFR agonist using a suite of chemical, biochemical, cellular, and animal experiments which include incisor eruption and wound-healing mouse models. A focused positional scanning pB1 library of Ala- and d-amino acid scans yielded a high-affinity pB1 analog, [K29k]pB1, with a 60-fold-improved EGFR affinity and mitogenicity. We show that the potency of [K29k]pB1 and the epidermal growth factor (EGF) is comparable in a diabetic mouse wound-healing model. We also show that both bleogen pB1 and [K29k]pB1 are hyperstable, being >100-fold more stable than EGF against proteolytic degradation. Overall, our discovery of a noncanonical proteolytic-resistant EGFR agonist scaffold could open new avenues for developing wound healing and skin regeneration therapeutics and biomaterials.

Enzyme mediated incorporation of zirconium-89 or copper-64 into a fragment antibody for same day imaging of epidermal growth factor receptor.

Identification of tumors which over-express Epidermal Growth Factor Receptor (EGFR) is important in selecting patients for anti-EGFR therapies. Enzymatic bioconjugation was used to introduce positron-emitting radionuclides (89Zr, 64Cu) into an anti-EGFR antibody fragment for Positron Emission Tomography (PET) imaging the same day as injection. A monovalent antibody fragment with high affinity for EGFR was engineered to include a sequence that is recognized by the transpeptidase sortase A. Two different metal chelators, one for 89ZrIV and one for 64CuII, were modified with a N-terminal glycine to enable them to act as substrates in sortase A mediated bioconjugation to the antibody fragment. Both fragments provided high-quality PET images of EGFR positive tumors in a mouse model at 3 hours post-injection, a significant advantage when compared to radiolabeled full antibodies that require several days between injection of the tracer and imaging. The use of enzymatic bioconjugation gives reproducible homogeneous products with the metal complexes selectively installed on the C-terminus of the antibody potentially simplifying regulatory approval.

GE11 Modified PLGA/TPGS Nanoparticles Targeting Delivery of Salinomycin to Breast Cancer Cells.

Salinomycin (Sal) is a potent inhibitor with effective anti-breast cancer properties in clinical therapy. The occurrence of various side effect of Sal greatly limits its application. The epidermal growth factor receptor (EGFR) family is a family of receptors highly expressed in most breast cancer cells. GE11 is a dodecapeptide which shows excellent EGFR affinity. A series of nanoparticles derivatives with GE11 peptide conjugated PLGA/TPGS were synthesized. Nanoprecipitation method was used to prepare the Sal loaded nanoparticles at the optimized concentration. The characterization, targeting efficacy, and antitumor activity were detected both in vitro and in vivo. Encapsulation of Sal in GE11 modified PLGA/TPGS nanoparticles shows an improved therapy efficacy and lower systemic side effect. This represents the delivery system a promising strategy to enhance the therapeutic effect against EGFR highly expressed breast cancer.

Discovery of Potent Dual EGFR/HER2 Inhibitors Based on Thiophene Scaffold Targeting H1299 Lung Cancer Cell Line.

Dual targeting of epidermal growth factor receptor (EGFR) and human EGFR-related receptor 2 (HER2) is a proven approach for the treatment of lung cancer. With the aim of discovering effective dual EGFR/HER2 inhibitors targeting non-small cell lung cancer cell line H1299, three series of thieno[2,3-d][1,2,3]triazine and acetamide derivatives were designed, synthesized, and biologically evaluated. The synthesized compounds displayed IC50 values ranging from 12 to 54 nM against H1299, which were superior to that of gefitinib (2) at 40 µM. Of the synthesized compounds, 2-(1H-pyrazolo[3,4-b]pyridin-3-ylamino)-N-(3-cyano4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)acetamide (21a) achieved the highest in vitro cytotoxic activity against H1299, with an IC50 value of 12.5 nM in situ, and 0.47 and 0.14 nM against EGFR and HER2, respectively, values comparable to the IC50 of the approved drug imatinib (1). Our synthesized compounds were promising, demonstrating high selectivity and affinity for EGFR/HER2, especially the hinge region forming a hydrophobic pocket, which was mediated by hydrogen bonding as well as hydrophobic and electrostatic interactions, as indicated by molecular modeling. Moreover, the designed compounds showed good affinity for T790M EGFR, one of the main mutants resulting in acquired drug resistance. Furthermore, both pharmacokinetic and physicochemical properties of the designed compounds were within the appropriate range for human usage as predicted by the in Silico ADME study. The designed compound (21a) might serve as an encouraging lead compound for the discovery of promising anti-lung cancer agents targeting EGFR/HER2.

PCR-based approach for site-specific conjugation of long double-stranded DNA to a single-domain VHH antibody.

Site-specific conjugation of double-stranded DNA using antibodies enables the development of unique applications for antibody-drug conjugates utilizing recent advances in nucleic acid medicines. Here, we describe a novel method to conjugate a camelid-derived single-domain VHH (variable domain of a heavy chain antibody) antibody with arbitrarily sized double-stranded DNA by PCR. Cysteine in anti-human epidermal growth factor receptor (EGFR) VHH was replaced by alanine, and an unpaired cysteine was introduced at the carboxyl terminus. These modifications enabled site-specific labelling with a maleimide-modified DNA oligo via thioether bond formation; the ensuing product-single-stranded DNA conjugated at the carboxyl terminus of VHH-retained its affinity for EGFR. To investigate whether this VHH-single-stranded DNA conjugate might be used as a forward primer, we subjected it to PCR, producing 100-500 bp DNA. We confirmed the amplification of the VHH-double-stranded DNA conjugate by examining its mobility on acrylamide gel; retention of the binding affinity of the conjugate for EGFR was identified by immuno-PCR.

CSIG-08. EXTRACELLULAR DOMAIN MUTATIONS IN EGFR RESULT IN A HYPERSENSITIVE RECEPTOR

Abstract INTRODUCTION The Epidermal Growth Factor Receptor (EGFR) is a driver gene that is amplified in more than half of all glioblastomas. After the initial high copy-number amplification, secondary missense mutations in the extracellular, ligand binding domain of EGFR can evolve. We here performed analysis on these mutations to better understand their function. METHODS Activation of EGFR-mutation constructs was measured by western blot and high-throughput quantitative image analysis using EGFR and phospho-EGFR specific antibodies. RESULTS Amphiregulin (AREG) is a low affinity EGFR ligand and was able to only marginally activate EGFRwt at high concentrations. In contrast however, AREG strongly activated all extracellular domain (ECD) mutation constructs (R108K, A289V and G598V). As expected, EGF-stimulation resulted in a strong activation in both EGFRwt and ECD mutation constructs. Further dose response analysis showed that in EGFRwt, all high affinity EGFR ligands (EGF, TGFa, HB-EGF and BTC) resulted in a strong activation and all low affinity ligands AREG, EREG and EPGN resulted in a markedly weaker activation. All ECD mutations however, showed strong activation towards all EGFR ligands, including the low affinity ligands (40%-80% of EGF stimulation). The constitutively active, ligand independent EGFRvIII mutation did not respond to any of the ligands and was mainly found to have an intracellular localization. Interestingly, the presence of ECD mutations and EGFRvIII are inversely correlated: in three large datasets (TCGA, Belob and Intellance 2), the majority of samples expressing EGFRvIII do not express additional ECD mutations and vice versa. ECD mutations likely affect stability of the tethered, inactive conformation thereby increasing exposure of the dimerization domain (II), resulting in increased ligand-sensitivity. CONCLUSION These experiments show that EGFR containing extracellular missense mutations render the receptor more sensitive to stimulation by low affinity ligands. Glioblastomas evolve to either become independent of ligand (EGFRvIII) or become ligand-hypersensitive (ECD mutations).

Abstract 218: AVID100 is an anti-EGFR ADC that promotes DM1-meditated cytotoxicity on cancer cells but not on normal cells

Abstract AVID100 is a novel rationally designed antibody drug conjugate (ADC) that specifically targets the epidermal growth factor receptor (EGFR). EGFR is highly expressed on a variety of cancers making it a promising target for ADCs. However, due to the presence of EGFR on normal skin cells, on-target off-tumor toxicity is a concern. AVID100 is an anti-EGFR-DM1 conjugate exhibiting high potency against cancer cells relative to unconjugated antibodies, while not exhibiting increased toxicity on normal cells. In a series of in vitro and in vivo experiments, we provide mechanistic evidence rationalizing why AVID100 shows higher cytotoxicity on tumor cells compared to normal cells. The antibody moiety of AVID100, denoted MAB100, was shown to have a high affinity for EGFR (approximately 2nM) and to compete with EGF for binding to the EGFR. Also, MAB100 prevented downstream signalling from EGFR. In addition to exhibiting full antagonist activity, MAB100 effectively delivered the microtubule inhibitor DM1 to tumor cells, as demonstrated by an increase in apoptosis in AVID100-treated tumor cells relative to MAB100-treated tumor cells. AVID100 was very effective on tumor cell lines derived from breast, head and neck, and lung cancers with the cytotoxic IC50 values generally correlating with the number of EGFR molecules on the cell surface. Importantly, on keratinocytes, AVID100 did not exhibit increased cytotoxicity relative to MAB100. We hypothesized that this lack of increase in cytotoxicity on keratinocytes is due to the antagonistic effect of MAB100 on EGFR signalling. Blocking the EGFR pathway in keratinocytes strongly inhibits their proliferation, which should protect them against the cytotoxic action of DM1. To address this hypothesis, we compared the effect of AVID100 to that of a non-antagonistic anti-EGFR ADC, huML66-DM1. As expected, both ADCs were highly effective at killing MDA-MB-468 cancer cells, confirming their ability to deliver DM1. In contrast, keratinocytes exhibited a significantly higher level of apoptosis in response to huML66-DM1 as compared to AVID100. These results confirm that the antagonistic nature of the antibody moiety of AVID100 plays a critical role in protecting keratinocytes from the cytotoxic effect of DM1. Finally, the activity of AVID100 was investigated in multiple mouse xenograft studies, including in MDA-MB-468 human breast adenocarcinoma, H292 NSCLC, and FaDu SSCHN models. AVID100 treatment significantly reduced tumor growth and caused tumor regressions in some of the mice, even when administered as a single dose. Toxicology studies in cynomolgus monkeys demonstrated that AVID100 was well tolerated at up to 4 weekly doses of 10mg/kg. AVID100 has completed a Phase 1 clinical trial with the recommended Phase 2 dose having been determined. The Phase 2 trial of AVID100 is ongoing. Citation Format: Michael J. Thwaites, Rene Figueredo, Gilles Tremblay, James Koropatnick, Victor Goldmacher, Maureen O’Connor-McCourt. AVID100 is an anti-EGFR ADC that promotes DM1-meditated cytotoxicity on cancer cells but not on normal 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 218.