EGFR-expressing Cell Research Articles

Fully human monoclonal antibody targeting the cysteine-rich substrate-interacting region of ADAM17 on cancer cells

ADAM17 sheds EGFR/erbB ligands and triggers oncogenic pathways that lead to the progression of solid tumors. We targeted the ADAM17 disintegrin and cysteine rich domain region (D+C) to generate a panel of single-chain antibody fragments (scFvs) that selectively bind to the D or C domains of ADAM17, but not of ADAM10 or ADAM19. From the panel, we selected one scFv, referred to as C12, based on its high binding affinity towards the target, and re-formatted it to a full IgG for further studies. High-resolution cryo-electron microscopy studies documented that the mAb binds to the ADAM17 C-domain that in ADAM proteases, notably ADAM10 and ADAM17, is known to impart substrate-specificity. The C12 mAb significantly inhibited EGFR phosphorylation in cancer cell lines by hindering the cleavage of EGFR ligands tethered to the cell surface. This inhibition provides a mechanism for potential anti-tumor effects, and indeed C12 diminished the viability of a variety of EGFR-expressing cancer cell lines. Cell-based ELISA studies revealed that C12 preferentially bound to activated ADAM17 present on tumor cells, as compared to the autoinhibited ADAM17 that is the predominant form on HEK293 and other non-tumor cells. C12 also exhibited tumor growth inhibition in an ovarian cancer xenograft mouse model. Consistent with its selective tumor cell binding in vitro, radioimmuno PET (positron emission tomography) imaging with 89Zr-DFO-C12 in mouse xenograft models confirmed tumoral accumulation of the C12 mAb.

Exploring Quinoxalinone Derivatives as Promising Epidermal Growth Factor Receptor (EGFR) Kinase Inhibitors for Cancer Therapy

E GFR plays an extensive role in the signaling pathway such as proliferation, migration, invasion. However, the malfunctioning of the epidermal growth factor receptor (EGFR) is a crucial factor in cancer progression. The search for new kinase inhibitors is necessary due to the evolving nature of diseases and the emergence of resistant strains, prompting the need for novel compounds that can effectively target and inhibit specific kinases for therapeutic purposes. This study explores quinoxalinone derivatives, comprised of benzene and pyrazine aromatic rings, as novel potential EGFR kinase inhibitors for cancer therapy, fulfilling an essential need in targeted cancer treatments. We utilized molecular docking to examine 46 synthesized quinoxalinone derivatives for their interaction with the tyrosine kinase domain of EGFR. Fifteen compounds exhibited strong binding affinities. Notably, LS3c, MN333, and MN343 displayed significant inhibitory effects on A431 cells with half-maximum inhibitory concentration (IC50) values comparable to gefitinib, erlotinib, and afatinib in enzymatic kinase assays. Subsequent experiments revealed that LS3c and MN343 effectively inhibit EGFR-expressing cell lines with low hepatotoxicity. MN343, the most potent compound, was selected for molecular dynamic simulation to understand its interaction with the tyrosine kinase of EGFR. To investigate the interaction between MN343 and EGFR’s tyrosine kinase, MM-PBSA analysis identified key residues (L694, V702, L768, M769, and L820) crucial for interaction, highlighting the potential of MN343 as a clinical EGFR tyrosine kinase inhibitor. The need for discovering new kinase inhibitors arises from the dynamic nature of diseases and the appearance of resistant strains, emphasizing the requirement for innovative compounds capable of targeting and inhibiting specific kinases effectively for therapeutic applications.

Anti-EGFR Antibody-Drug Conjugate Carrying an Inhibitor Targeting CDK Restricts Triple-Negative Breast Cancer Growth.

Anti-EGFR antibodies show limited response in breast cancer, partly due to activation of compensatory pathways. Furthermore, despite the clinical success of cyclin-dependent kinase (CDK) 4/6 inhibitors in hormone receptor-positive tumors, aggressive triple-negative breast cancers (TNBC) are largely resistant due to CDK2/cyclin E expression, whereas free CDK2 inhibitors display normal tissue toxicity, limiting their therapeutic application. A cetuximab-based antibody drug conjugate (ADC) carrying a CDK inhibitor selected based on oncogene dysregulation, alongside patient subgroup stratification, may provide EGFR-targeted delivery. Expressions of G1/S-phase cell cycle regulators were evaluated alongside EGFR in breast cancer. We conjugated cetuximab with CDK inhibitor SNS-032, for specific delivery to EGFR-expressing cells. We assessed ADC internalization and its antitumor functions in vitro and in orthotopically grown basal-like/TNBC xenografts. Transcriptomic (6,173 primary, 27 baseline, and matched post-chemotherapy residual tumors), single-cell RNA sequencing (150,290 cells, 27 treatment-naïve tumors), and spatial transcriptomic (43 tumor sections, 22 TNBCs) analyses confirmed expression of CDK2 and its cyclin partners in basal-like/TNBCs, associated with EGFR. Spatiotemporal live-cell imaging and super-resolution confocal microscopy demonstrated ADC colocalization with late lysosomal clusters. The ADC inhibited cell cycle progression, induced cytotoxicity against high EGFR-expressing tumor cells, and bystander killing of neighboring EGFR-low tumor cells, but minimal effects on immune cells. Despite carrying a small molar fraction (1.65%) of the SNS-032 inhibitor, the ADC restricted EGFR-expressing spheroid and cell line/patient-derived xenograft tumor growth. Exploiting EGFR overexpression, and dysregulated cell cycle in aggressive and treatment-refractory tumors, a cetuximab-CDK inhibitor ADC may provide selective and efficacious delivery of cell cycle-targeted agents to basal-like/TNBCs, including chemotherapy-resistant residual disease.

A novel dihydroacridine derivative targets epidermal growth factor receptor-expressing cancer cells in vitro and in vivo.

Small molecules are considered a source of novel medicines targeting carcinogenic intracellular pathways including epidermal growth factor receptor (EGFR) signaling. The main goal of the study is to assess whether LHT-17-19 could be considered an effective target molecule against EGFR-expressing tumor cells in silico, in vitro, and in vivo. This was an in vivo, ex vivo, and in vivo experimental study. LHT-17-19 affinity to EGFR's kinase domain was assessed by the ligand's molecular docking. EGFR-expressing Hs746T human gastric cancer cell culture and patient-derived organoid (PDO) model of EGFR-positive breast cancer (BC) were used for in vitro assessment of the molecule anticancer property. IC50 and GI50 indexes were estimated using MTT- and MTS-based tests, respectively. Anticancer activity of LHT-17-19 against EGFR-expressing mutant lung carcinoma was studied on patient-derived xenograft (PDX) model established in 10 humanized BALB/c male mice. Continuous variables were presented as a mean ± standard deviation. Intergroup differences were assessed by two-way t-test. Kaplan-Meier's curves were used for survival analysis. High affinity of LHT-17-19 for the EGFR kinase domain with dG score -7.9 kcal/mol, EDoc-5.45 kcal/mol, and Ki 101.24 uM was due to intermolecular π-σ bonds formation and the ligand intramolecular transformation. LHT-17-19 induced anti-EGFR-expressing gastric cancer cells cytotoxicity with IC50 0.32 µM (95% confidence interval [CI] 0.11-0.54 µM). The derivative inhibited growth of EGFR-expressing BC PDO with GI50 16.25 µM (95% CI 4.44-28.04 µM). 2 mg/kg LHT-17-19 intravenously daily during 7 days inhibited PDX tumor growth and metastatic activity, prolonged animals' survival, and eliminated EGFR-mutant lung cancer cells from residual tumor's node. LHT-17-19 may be considered a molecular platform for further search of promising molecules, EGFR-expressing cancer cell inhibitors.

Abstract 7194: Targeting AXL and MCL-1 to eradicate lazertinib tolerance in EGFR-mutated NSCLC cells

Abstract Lazertinib, a novel third-generation EGFR-tyrosine kinase inhibitor, has shown marked efficacy in patients with EGFR-mutant lung cancer. However, after various periods of therapeutic intervention, most patients eventually acquire resistance to lazertinib. A potential therapeutic approach to address this clinical issue is to overcome the initial drug resistance mechanism. To determine the underlying adaptive lazertinib resistance mechanisms, we evaluated signal transduction, cell apoptosis, and drug sensitivity in mutant EGFR-expressing non-small cell lung cancer (NSCLC) cells treated with lazertinib. The siRNA screening assay demonstrated that AXL knockdown significantly inhibited cell viability in the presence of lazertinib, indicating that AXL activation contributes to lazertinib resistance. However, long-term culture with a combination of lazertinib and AXL inhibitors eventually led to the proliferation of residual cells and increased MCL-1 expression, which was mediated by the nuclear translocation of the transcription factor YAP. Cell-based assays showed that triple therapy with an MCL-1 or YAP inhibitor, in combination with EGFR-TKI lazertinib, an AXL inhibitor, significantly reduced cell viability and increased apoptosis. These results demonstrate that AXL and YAP/MCL-1 signals contribute to the adaptive lazertinib resistance in EGFR-mutant NSCLC cells, suggesting that the initial dual inhibition of AXL and YAP/MCL-1 might be highly effective in eliminating lazertinib-resistant cells. Citation Format: Tadaaki Yamada, Yohei Matsui, Koichi Takayama. Targeting AXL and MCL-1 to eradicate lazertinib tolerance in EGFR-mutated NSCLC cells [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 7194.

Abstract 6353: AM105: A novel bispecific antibody with Anti 4-1BB affibodies and EGFR antibody

Abstract T cell engaging bispecific antibodies have emerged as promising treatments for hematologic malignancies. While most antibodies are CD3-based, offering therapeutic benefits, they are often associated with severe side effects and limited efficacy in solid tumors. To address these challenges, we present AM105, a groundbreaking anti 4-1BB affibodies based bispecific antibody designed to target EGFR. We carefully engineered AM105 with distinct binding affinities for EGFR (KD = 1.8 nM) and 4-1BB (KD = 60 nM), favoring EGFR binding. Affibody specificity was confirmed through a cross-reactivity test with proteins of TNF-receptor superfamily and 21 cell lines expressing 4-1BB or not. In cytotoxicity assays, AM105 exhibited superior tumor cell killing compared to cetuximab, particularly in EGFR-expressing cell lines. Notably, AM105 displayed remarkable efficacy in cell lines harboring RAS and/or BRAF mutations, traditionally unresponsive to EGFR-targeting treatments. In vivo experiments utilizing humanized 4-1BB mice demonstrated AM105's exceptional tumor cell elimination compared to cetuximab. The anti-tumor effects persisted even in the face of new tumor cell introductions, suggesting the induction of T cell memory function. Our findings collectively establish AM105 as a potent therapeutic agent with strong anti-tumor T cell activity. The unique 4-1BB based Affibodies (AffiMab format) of AM105 holds promise for addressing the limitations of current bispecific antibodies, positioning it as a potential breakthrough in cancer immunotherapy. Citation Format: Dong-Wook Kim, Hyun-Jong Lee, Seong Yeol Kim, Min Yoon, Youngha Lee, In-Sik Hwang, Yoon Lee, Jong-Hoon Kim, Jong-Seo Lee. AM105: A novel bispecific antibody with Anti 4-1BB affibodies and EGFR antibody [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 6353.

Abstract 1892: KK2260: A fully human tetravalent bispecific antibody targeting TfR1 and EGFR for the treatment of EGFR-expressing tumors

Abstract Background: TfR1 is a transmembrane glycoprotein involved in iron uptake and regulation of cell growth. High TfR1 expression has been reported in different types of cancers, therefore recognized as a target molecule for cancer therapy. Despite the promise of potent efficacy of TfR1-targeted agents, there is a risk of side effects (i.e., severe anemia), since TfR1 is also highly expressed in certain normal cells (e.g., reticulocytes). KK2260 is a fully human tetravalent bispecific antibody (bsAb) based on REGULGENTTM technology targeting TfR1 and EGFR. This bsAb was designed for EGFR-expressing cell selective anti-cancer drug which could not be achieved by conventional monospecific Ab. In this study, we evaluated the mechanism of action (MOA), anti-cancer effect, and toxicity of KK2260. Methods: Binding activity of KK2260 to TfR1 and EGFR was evaluated by surface plasmon resonance method. Ligand blocking activity was evaluated by binding competition on esophageal squamous cell carcinoma (ESCC) OE21 cells. Growth inhibitory activity of KK2260 on cancer cells or hematopoietic progenitor cells was evaluated by proliferation inhibition assay. In some studies, excessive iron or anti-EGFR parent Ab was added. Effect on the cell surface target expression levels was evaluated by flow cytometry. The intracellular iron level was evaluated by cell imaging. Effect on EGF induced EGFR phosphorylation was evaluated by Western blotting. The in vivo efficacy of KK2260 was evaluated in cell line-derived and patient-derived xenograft (PDX) models of ESCC selected for high EGFR expression level. The toxicity of KK2260 was evaluated in cynomolgus monkeys. Results: KK2260 bound to TfR1 and EGFR with no ligand binding inhibition. KK2260 inhibited cell growth of moderate to high EGFR-expressing cancer cells, but not against EGFR-negative cancer cells or hematopoietic progenitor cells. KK2260 downregulated TfR1 expression on OE21 cells and the intracellular iron level decreased, but no effect was observed on EGFR phosphorylation. The growth inhibitory activity of KK2260 was abolished by adding excessive amounts of iron or reduced by inhibiting the binding to EGFR. Potent anti-tumor activity was observed in the ESCC PDX models with tumor regression. In the intermittent-dose toxicity study of cynomolgus monkeys, KK2260 was well-tolerated. Conclusions: KK2260 demonstrated potent anti-cancer effect both in vitro and in vivo. Intriguingly, KK2260 did not inhibit EGFR phosphorylation while EGFR-binding dependent TfR1 downregulation resulted in intracellular iron deficiency, which was considered as the MOA of KK2260. KK2260 was well tolerated in non-human primates. These preclinical data suggest the unique property of KK2260 is expected to provide significant benefit to patients with advanced ESCC and other EGFR-expressing tumors and Phase 1 study is currently on going in Japan (jRCT2031230372). Citation Format: Keisuke Mitamura, Hironori Otsuki, Keiko Nakahashi, Ayaka Kitagawa, Masayo Kamigaki, Yohei Kurio, Miho Inoue, Yasunori Uemura. KK2260: A fully human tetravalent bispecific antibody targeting TfR1 and EGFR for the treatment of EGFR-expressing tumors [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 1892.

Efficacy of depatuxizumab mafodotin (ABT-414) in preclinical models of head and neck cancer.

Epidermal growth factor receptor (EGFR) is highly expressed in 80-90% of head and neck squamous cell carcinomas (HNSCCs), making it an ideal target for antibody-drug conjugates. Depatuxizumab mafodotin (ABT-414), is an EGFR-targeting ADC comprised of the monoclonal antibody ABT-806 conjugated to monomethyl auristatin F, a tubulin polymerization inhibitor. This study assessed the in vivo efficacy of ABT-414 in HNSCC. The effects of ABT-414 on HNSCCs were determined using in vitro cytotoxicity assays and in vivo flank xenograft mouse models. The distribution of ABT-414 was assessed ex vivo via optical imaging methods using a conjugate of ABT-414 to the near-infrared agent IRDye800. In vitro treatment of high EGFR-expressing human HNSCC cell lines (UMSCC47 and FaDu) with ABT-414 (0-3.38 nM) resulted in dose-dependent cell death (IC50 values of 0.213 nM and 0.167 nM, respectively). ABT-414 treatment of the FaDu mouse xenografts displayed antitumor activity (P = 0.023) without a change in body mass (P = 0.1335), whereas treatment of UMSCC47 did not generate a significant response (P = 0.1761). Fluorescence imaging revealed ABT-414-IRDye800 accumulation in the tumors of both FaDu and UMSCC47 cell lines, with a signal-to-background ratio of >10. ABT-414 treatment yielded antitumor activity in FaDu tumors, but not in UMSCC47, highlighting the potential for ABT-414 efficacy in high EGFR-expressing tumors. Although ABT-414-IRDye800 localized tumors in both cell lines, the differing antitumor responses highlight the need for further investigation into the role of the tumor microenvironment in drug delivery.

Exploring the Sensitivity of Antibody-Drug Conjugate Efficacy to the Selection of Payload, Antibody, and Cell line.

Antibody-drug conjugates (ADCs) make up a growing class of targeted therapeutics with important applications in cancer treatment. ADCs are highly modular in nature and thus can be engineered to target any cancer type, but their efficacy is strongly influenced by the specific choice of payload, antibody, and target cell. Considering the number of possible antibody-payload combinations, ADC development would benefit from an efficient method to narrow the number of ADC compositions to those with the highest and most universal potency prior to assessing pharmacokinetics and pharmacodynamics in animal models. To facilitate the identification of optimal ADC compositions, we describe the use of photoreactive antibody-binding domain-drug conjugates (known commercially as oYo-Link) to enable the site-specific labeling of off-the-shelf antibodies. This approach allows for the rapid generation of ADCs with a drug-to-antibody ratio of ∼2 with no subsequent purification required. As a demonstration of this approach, ADCs were generated with different combinations of tubulin-inhibitor drugs (DM1, DM4, VcMMAE, and VcMMAF) and anti-EGFR antibodies (cetuximab, panitumumab, anti-EGFR clone 425, and anti-EGFR clone 528) and were delivered to three EGFR-expressing cell lines (A431, A549, and MDA-MB-231). Real-time cytolysis assays indicated that the most effective antibody varied based on the choice of cell line: cetuximab was most potent against A431 cells, while 425 and 528 led to the greatest cytotoxicity against A549 and MDA-MB-231 cells. These results did not correlate with differences in measured anti-EGFR binding affinity as cetuximab had the highest affinity across all three cell lines, while 425 and 528 had the lowest affinities for all three cell lines. Panitumumab, which had the second-highest anti-EGFR affinity, exhibited the least effective cytolysis across A431, A549, and MDA-MB-231 cells. By demonstrating that ADC potency toward a given target is dependent on both the antibody and drug chosen, these findings can guide the selection of ADCs for further in vivo analysis.

Near-infrared photoimmunotherapy in the models of hepatocellular carcinomas using cetuximab-IR700.

Epidermal growth factor receptor (EGFR) has emerged as an important therapeutic target in many cancers, and overexpression of EGFR is frequently observed in hepatocellular carcinomas (HCCs). Near-infrared photoimmunotherapy (NIR-PIT) is a new anticancer treatment that selectively damages the cell membrane of cancer cells after NIR light-induced photochemical reaction of IR700, which is bound to a targeting antibody on the cell membrane. NIR-PIT using cetuximab-IR700 has already been approved in Japan, is under review by the US Food and Drug Administration (FDA) for advanced head and neck cancers, and its safety has been established. However, EGFR has not been investigated as a target in NIR-PIT in HCCs. Here, we investigate the application of NIR-PIT using cetuximab-IR700 to HCCs using xenograft mouse models of EGFR-expressing HCC cell lines, Hep3B, HuH-7, and SNU-449. In vitro NIR-PIT using EGFR-targeted cetuximab-IR700 killed cells in a NIR light dose-dependent manner. In vivo NIR-PIT resulted in a delayed growth compared with untreated controls. In addition, in vivo NIR-PIT in both models showed histological signs of cancer cell damage, such as cytoplasmic vacuolation and nuclear dysmorphism. A significant decrease in Ki-67 positivity was also observed after NIR-PIT, indicating decreased cancer cell proliferation. This study suggests that NIR-PIT using cetuximab-IR700 has potential for the treatment of EGFR-expressing HCCs.

Anti-Tumor Activity of Novel Nimotuzumab-Functionalized Gold Nanoparticles as a Potential Immunotherapeutic Agent against Skin and Lung Cancers.

The epidermal growth factor receptor (EGFR) is vital for many different types of cancer. Nimotuzumab (NmAb), an anti-EGFR monoclonal antibody (mAb), is used against some of EGFR-overexpressed cancers in various countries. It targets malignant cells and is internalized via receptor-mediated endocytosis. We hypothesized that mAb-nanoparticle conjugation would provide an enhanced therapeutic efficacy, and hence we conjugated NmAb with 27 nm spherical gold nanoparticles (AuNPs) to form AuNP-NmAb nanoconjugates. Using biophysical and spectroscopic methods, including ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and Fourier-transform infrared spectroscopy (FTIR), the AuNP-NmAb complex was characterized. Furthermore, in vitro studies were performed using a medium-level EGFR-expressing skin cancer cell (A431, EGFRmedium) and low-level EGFR-expressing lung cancer cell (A549, EGFRlow) to evaluate anti-tumor and cellular uptake efficiency via MTT assay and single-particle inductively coupled plasma mass spectrometry (spICP-MS), respectively. In comparison to NmAb monotherapy, the AuNP-NmAb treatment drastically reduced cancer cell survivability: for A431 cells, the IC50 value of AuNP-NmAb conjugate was 142.7 µg/mL, while the IC50 value of free NmAb was 561.3 µg/mL. For A549 cells, the IC50 value of the AuNP-NmAb conjugate was 163.6 µg/mL, while the IC50 value of free NmAb was 1,082.0 µg/mL. Therefore, this study highlights the unique therapeutic potential of AuNP-NmAb in EGFR+ cancers and shows the potential to develop other mAb nanoparticle complexes for a superior therapeutic efficacy.

Development of 177Lu-Cetuximab-PAMAM dendrimeric nanosystem: a novel theranostic radioimmunoconjugate.

Epidermal growth factor receptors (EGFRs) are overexpressed in a wide range of tumors and are attractive candidates to target in targeted therapies. This study aimed to introduce a novel radiolabeled compound, 177Lu-cetuximab-PAMAM G4, for the treatment of EGFR-expressing tumors. In this study, the cetuximab mAb was bound to PAMAM G4 and labeled with 177Lu via DTPA-CHX chelator. The synthesized nanosystem was confirmed by different analyses such as DLS, FT-IR, TEM, and RT-LC. Cell viability of the radioimmunoconjugate was assessed over the EGFR-expressing cell line of SW480. The biodistribution of 177Lu-Cetuximab-PAMAMG4 was determined in different intervals after injection of the radiolabeled compound in normal and tumoral nude mice via scarification and SPECT images. The average size of PAMAM G4 and PAMAM-Cetuximab-DTPA-CHX nanoparticles were 2 and 70nm, respectively. 177Lu-Cetuximab-PAMAMG4 was prepared with radiochemical purity of more than 98%. The survival rates of SW480 cells at 24, 48, and 72h post-treatment with177Lu-Cetuximab-PAMAMG4 (500nM) were 18%, 15%, and 14%, respectively. The biodistribution studies showed a significant accumulation of 177Lu-Cetuximab-PAMAM in the EGFR-expressing tumor. According to the results, this new agent can be considered as an efficient therapeutic complex for tumors expressing EGFR receptors.

Abstract 1749: A new class of DNA sequence-selective G-A cross-linking antibody-drug conjugate (ADC) payloads

Abstract Antibody-Drug Conjugates (ADCs) are rapidly growing in importance as a targeted cancer therapy, with over ten approved, and many currently undergoing clinical trials. ADCs comprise of a cytotoxic agent (i.e., the "payload") conjugated via a chemical linker to a tumor-targeting antibody. There is a demand for novel ADC payloads with unique mechanisms of action, enhanced tolerability profiles and improved physicochemical properties. Such payloads could lead to ADCs with therapeutic efficacy in patients resistant to other therapies, and payloads with reduced hydrophobicity should lead to improved conjugation, minimal aggregation, and higher Drug-Antibody Ratios (DARs). We report here, studies on a novel class of Cyclopropabenzindole-Pyridinobenzodiazepine (CBI-PDD) payloads, designed through molecular modeling, which form cross-links between Guanine and Adenine bases within the DNA minor groove with defined sequence specificity. Eleven novel analogs will be described which have been structurally modified with various functional groups to allow tunable hydrophobicity, and new vectors through which antibodies may be attached. Most of these analogs are highly cytotoxic, with some exhibiting IC50 values in tumor cells down to the femtomolar range (e.g., FGX37-140, 0.9 pM in both RAJI and Jurkat cells, 72 h incubation). The DNA interactivity of these analogs has been studied using a range of methods such as gel-based DNA footprinting and cross-linking, FRET melting and Transcription Factor (TF) Array assays, the results of which will be described. Overall, the analogs appear to favor the formation of intrastrand rather than interstrand DNA cross-links and can inhibit the DNA binding of several key cancer-related transcription factors such as NFκB. To explore the potential of these analogs as ADC payloads, one member, FGX8-46, was conjugated to the EGFR-targeting antibody Cetuximab in stochastic fashion (DAR2) to produce Cetuximab-(FGX16-11). This ADC had an unexpectedly high Maximum Tolerated Dose (MTD) in a standard mouse model of at least 45 mg/kg, perhaps reflecting the novel mechanism of action of the payload. It was then evaluated in a Human Tumor Xenograft study based on BALB/c mice transplanted with the EGFR-expressing human colon cancer cell line SW-48 using single doses ranging from 1 mg/kg to 40 mg/kg. Cetuximab-(FGX16-11) was active at all dose levels including 1 mg/kg which provided tumor suppression out to approximately three weeks. Complete tumor suppression out to 50 days was seen with 20 mg/kg. Overall, the unique mechanism of action, potent cytotoxicity, and excellent in vivo tolerability and significant efficacy in ADC format, make the CBI-PDDs a promising new class of ADC payloads suitable for further development. Citation Format: George Procopiou, Paul J. Jackson, Daniella M. di Mascio, Jennifer L. Auer, Paolo Andriollo, Ilona Pysz, Khondaker M. Rahman, Keith R. Fox, David E. Thurston. A new class of DNA sequence-selective G-A cross-linking antibody-drug conjugate (ADC) payloads [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 1749.

Abstract 5423: Translational PK/PD/efficacy modeling and efficacious human dose prediction for a first-in-class MUC1-EGFR (M1231) bispecific antibody drug conjugate

Abstract Introduction: M1231 is a first-in-class bispecific antibody drug conjugate (ADC) targeting mucin-1 (MUC1) and epidermal growth factor receptor (EGFR), that is conjugated with a novel hemiasterlin-related microtubule inhibitor payload. Following dose, M1231 binds to EGFR and co-binds to tumor-associated hypoglycosylated MUC1, internalizes into the tumor cell and traffics to lysosomes where the payload is enzymatically released to affect cell viability. Methods: A Multi-scale Systems Pharmacology model was developed to account for the ADC’s disposition and interactions with the underlying physiologic system, resulting in intracellular payload release in tumor cells to drive tumor growth inhibition (TGI). An in vitro model quantified ADC internalization and lysosomal trafficking in the MUC1 and EGFR-expressing cancer cell lines MDA-MB-468 and OVCAR-3. TGI was assessed in mice bearing MUC1-tumors from the squamous NSCLC patient-derived xenograft model, LUX003. Pharmacokinetics in cynomolgus monkeys was modeled using a Target Mediated Drug Disposition model and was allometrically scaled to humans. Data Summary: All preclinical modeling results were integrated and scaled to simulate plasma M1231 concentrations to predict the human dose and corresponding exposures. Tumor stasis was estimated to begin at a dose of 2.4 mg/kg every 3 weeks (Q3W) with a maximum tumor regression achieved at a dose of 4.3 mg/kg Q3W. Conclusions: The quantitative systems pharmacology model-based efficacious dose prediction range of 2.4 mg/kg to 4.3 mg/kg dosed Q3W informed the design of the ongoing M1231 first-in-human trial (NCT04695847). Citation Format: Anup Zutshi, Berend Neuteboom, Seema Kumar, Willem Sloot, Christine Knuehl, Julia Dotterweich, Jianguo Ma, Christiane Amendt, Karthik Venkatakrishnan, Taeshin Park, John Pappas, Kyoung-Ae Kim. Translational PK/PD/efficacy modeling and efficacious human dose prediction for a first-in-class MUC1-EGFR (M1231) bispecific antibody drug conjugate [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 5423.

Structure-based design and synthesis of a novel long-chain 4''-alkyl ether derivative of EGCG as potent EGFR inhibitor: in vitro and in silico studies.

Herein, we report the discovery of a novel long-chain ether derivative of (−)-epigallocatechin-3-gallate (EGCG), a major green tea polyphenol as a potent EGFR inhibitor. A series of 4′′-alkyl EGCG derivatives have been synthesized via regio-selectively alkylating the 4′′ hydroxyl group in the D-ring of EGCG and tested for their antiproliferative activities against high (A431), moderate (HeLa), and low (MCF-7) EGFR-expressing cancer cell lines. The most potent compound, 4′′-C14 EGCG showed the lowest IC50 values across all the tested cell lines. 4′′-C14 EGCG was also found to be significantly more stable than EGCG under physiological conditions (PBS at pH 7.4). Further western blot analysis and imaging data revealed that 4′′-C14 EGCG induced cell death in A431 cells with shrunken nuclei, nuclear fragmentation, membrane blebbing, and increased population of apoptotic cells where BAX upregulation and BCLXL downregulation were observed. In addition, autophosphorylation of EGFR and its downstream signalling proteins Akt and ERK were markedly inhibited by 4′′-C14 EGCG. MD simulation and the MM/PBSA analysis disclosed the binding mode of 4′′-C14 EGCG in the ATP-binding site of EGFR kinase domain. Taken together, our findings demonstrate that 4′′-C14 EGCG can act as a promising potent EGFR inhibitor with enhanced stability.

Nanobody-targeted photodynamic therapy for the treatment of feline oral carcinoma: a step towards translation to the veterinary clinic.

Nanobody-targeted photodynamic therapy (NB-PDT) has been developed as a potent and tumor-selective treatment, using nanobodies (NBs) to deliver a photosensitizer (PS) specifically to cancer cells. Upon local light application, reactive oxygen species are formed and consequent cell death occurs. NB-PDT has preclinically shown evident success and we next aim to treat cats with oral squamous cell carcinoma (OSCC), which has very limited therapeutic options and is regarded as a natural model of human head and neck SCC. Immunohistochemistry of feline OSCC tissue confirmed that the epidermal growth factor receptor (EGFR) is a relevant target with expression in cancer cells and not in the surrounding stroma. Three feline OSCC cell lines were employed together with a well-characterized human cancer cell line (HeLa), all with similar EGFR expression, and a low EGFR-expressing human cell line (MCF7), mirroring the EGFR expression level in the surrounding mucosal stroma. NBA was identified as a NB binding human and feline EGFR with comparable high affinity. This NB was developed into NiBh, a NB-PS conjugate with high PS payload able to effectively kill feline OSCC and HeLa cell lines, after illumination. Importantly, the specificity of NB-PDT was confirmed in co-cultures where only the feline OSCC cells were killed while surrounding MCF7 cells were unaffected. Altogether, NiBh can be used for NB-PDT to treat feline OSCC and further advance NB-PDT towards the human clinic.

A novel diphtheria toxin-based bivalent human EGF fusion toxin for treatment of head and neck squamous cell carcinoma.

Epidermal growth factor receptor (EGFR) is often overexpressed in head and neck squamous cell carcinoma (HNSCC) and represents a top candidate for targeted HNSCC therapy. However, the clinical effectiveness of current Food and Drug Administration (FDA)‐approved drugs targeting EGFR is moderate, and the overall survival rate for HNSCC patients remains low. Therefore, more effective treatments are urgently needed. In this study, we generated a novel diphtheria toxin‐based bivalent human epidermal growth factor fusion toxin (bi‐EGF‐IT) to treat EGFR‐expressing HNSCC. Bi‐EGF‐IT was tested for in vitro binding affinity, cytotoxicity, and specificity using 14 human EGFR‐expressing HNSCC cell lines and three human EGFR‐negative cancer cell lines. Bi‐EGF‐IT had increased binding affinity for EGFR‐expressing HNSCC compared with the monovalent version (mono‐EGF‐IT), and both versions specifically depleted EGFR‐positive HNSCC, but not EGFR‐negative cell lines, in vitro. Bi‐EGF‐IT exhibited a comparable potency to that of the FDA‐approved EGFR inhibitor, erlotinib, for inhibiting HNSCC tumor growth in vivo using both subcutaneous and orthotopic HNSCC xenograft mouse models. When tested in an experimental metastasis model, survival was significantly longer in the bi‐EGF‐IT treatment group than the erlotinib treatment group, with a significantly reduced number of metastases compared with mono‐EGF‐IT. In addition, in vivo off‐target toxicities were significantly reduced in the bi‐EGF‐IT treatment group compared with the mono‐EGF‐IT group. These results demonstrate that bi‐EGF‐IT is more effective and markedly less toxic at inhibiting primary HNSCC tumor growth and metastasis than mono‐EGF‐IT and erlotinib. Thus, the novel bi‐EGF‐IT is a promising drug candidate for further development.

Ultrabright Terbium Nanoparticles for FRET Biosensing and in Situ Imaging of Epidermal Growth Factor Receptors*.

Lanthanide-doped nanoparticles (LnNPs) have become an important class of fluorophores for advanced biosensing and bioimaging. LnNPs that are photosensitized by surface-attached antenna ligands can possess exceptional brightness. However, their functional bioconjugation remains an important challenge for their translation into bioanalytical applications. To solve this problem, we designed a ligand that can be simultaneously applied as efficient light harvesting antenna for Tb surface ions and strong linker of biomolecules to the LnNPs surfaces. To demonstrate generic applicability of the photosensitized TbNP-bioconjugates, we applied them in two prototypical applications for biosensing and bioimaging. First, in-solution biorecognition was shown by time-resolved Förster resonance energy transfer (FRET) between streptavidin-functionalized TbNPs to biotinylated dyes (ATTO 610). Second, in situ detection of ligand-receptor binding on cells was accomplished with TbNP-antibody (Matuzumab) conjugates that could specifically bind to transmembrane epidermal growth factor receptors (EGFR). High specificity and sensitivity were demonstrated by time-gated imaging of EGFR on both strongly (A431) and weakly (HeLa and Cos7) EGFR-expressing cell lines, whereas non-expressing cell lines (NIH3T3) and EGFR-passivated A431 cells did not show any signals. Despite the relatively large size of TbNP-antibody conjugates, they could be internalized by A431 cells upon binding to extracellular EGFR, which showed their potential as bright and stable luminescence markers for intracellular signaling.

Vandetanib inhibits cell growth in EGFR-expressing cutaneous squamous cell carcinoma

Advanced cutaneous squamous cell carcinoma (SCC) responds poorly to chemotherapy, leading to significant morbidity or death. Overexpression of epidermal growth factor receptor (EGFR) is frequently observed in advanced cutaneous SCC. Vandetanib is a multiple tyrosine kinase targeting vascular endothelial growth factor receptor-2 (VEGFR2), EGFR, and the rearranged during transfection (RET) proto-oncogene. Vandetanib has been reported to inhibit tumor growth in head and neck SCC. However, the efficacy of vandetanib against cutaneous SCC has not been thoroughly investigated. The aim of this study is to evaluate the efficacy of vandetanib against cutaneous SCC in vitro and in vivo. Vandetanib is found to inhibit the proliferation of cutaneous SCC cells as assessed by cell viability and clonogenic assay. Cell death analysis indicates that vandetanib induces cell death in SCC cells but not in normal human keratinocytes or fibroblasts. The in vivo anti-tumor effect of vandetanib is shown in xenograft tumor models using A431 SCC cells. Mechanistically, vandetanib suppresses the phosphorylation of EGFR in SCC cells. Clinically, EGFR expression levels are elevated in cutaneous SCC specimens, relative to normal epidermis. In conclusion, we identified vandetanib as a novel therapeutic option for cutaneous SCC, especially in tumors with high EGFR expression.

Design and Synthesis of some new 2,4,6-trisubstituted quinazoline EGFR inhibitors as targeted anticancer agents.

The present study describes the synthesis of 6-bromo-2-(pyridin-3-yl)-4-substituted quinazolines starting from 4-chloro derivative VI via the reaction with either phenolic compounds to obtain VIIa-f, IXa-d, 2-amino-6-(un)substituted benzothiazole to produce VIIIa-c or hydrazine hydrate to give X. Reaction of the hydrazino functionality of X with appropriate acid anhydride, acid chloride or aldehyde affords XIa-c, XIIa-c and XIVa-i, respectively. The target compounds were screened for their efficacy as EGFR inhibitors compared to gefitinib. Compounds eliciting superior EGFR inhibitory activity were further screened for their in vitro cytotoxicity against two human cancer cell lines namely: MCF7 (breast) and A549 (lung), in addition to normal fibroblast cell WI38 relative to gefitinib as a reference. Furthermore, compounds that showed potent inhibitory activity on wild-type EGFR were screened against mutant EGFR and assayed for their cytotoxicity against mutant EGFR-expressing cell lines PC9 and HCC827. The unsubstituted benzothiazol-2-amine VIIa showing superior EGFR inhibition (IC50=0.096µM) and anticancer activity against MCF-7 cell line (IC50 =2.49µM) was subjected to cell cycle analysis and apoptotic assay. Moreover, a molecular docking study was performed to investigate the interaction of some representive compounds with the active site of EGFR- TK.