Small-molecule Epidermal Growth Factor Receptor Research Articles

Synthetic Routes and Clinical Application of Representative Small-Molecule EGFR Inhibitors for Cancer Therapy.

The epidermal growth factor receptor (EGFR) plays a pivotal role in cancer therapeutics, with small-molecule EGFR inhibitors emerging as significant agents in combating this disease. This review explores the synthesis and clinical utilization of EGFR inhibitors, starting with the indispensable role of EGFR in oncogenesis and emphasizing the intricate molecular aspects of the EGFR-signaling pathway. It subsequently provides information on the structural characteristics of representative small-molecule EGFR inhibitors in the clinic. The synthetic methods and associated challenges pertaining to these compounds are thoroughly examined, along with innovative strategies to overcome these obstacles. Furthermore, the review discusses the clinical applications of FDA-approved EGFR inhibitors such as erlotinib, gefitinib, afatinib, and osimertinib across various cancer types and their corresponding clinical outcomes. Additionally, it addresses the emergence of resistance mechanisms and potential counterstrategies. Taken together, this review aims to provide valuable insights for researchers, clinicians, and pharmaceutical scientists interested in comprehending the current landscape of small-molecule EGFR inhibitors.

Epidermal growth factor receptor inhibition potentiates chemotherapeutics-mediated sensitization of metastatic breast cancer stem cells.

Metastasis has been a cause of the poor prognosis and cancer relapse of triple-negative breast cancer (TNBC) patients. The metastatic nature of TNBC is contributed by the breast cancer stem cells (CSCs) which have been implicated in tumorigenesis. Higher expression of epidermal growth factor receptor (EGFR) in breast CSCs has been used as a molecular target for breast cancer therapeutics. Thus, it necessitates the design and generation of efficacious EGFR inhibitors to target the downstream signaling associated with the cellular proliferation and tumorigenesis of breast cancer. To generate efficacious EGFR inhibitors that can potentiate the chemotherapeutic-mediated mitigation of breast cancer tumorigenesis. We identified small molecule EGFR inhibitors using molecular docking studies. In-vitro screening of the compounds was undertaken to identify the cytotoxicity profile of the small-molecule EGFR inhibitors followed by evaluation of the non-cytotoxic compounds in modulating the doxorubicin-induced migration, in-vitro tumorigenesis potential, and their effect on the pro-apoptotic genes' and protein markers' expression in TNBC cells. Compound 1e potentiated the doxorubicin-mediated inhibitory effect on proliferation, migration, in-vitro tumorigenesis capacity, and induction of apoptosis in MDA-MB-231 cells, and in the sorted CD24+-breast cancer cells and CD24-/CD44+-breast CSC populations. Orthotopic xenotransplantation of the breast CSCs-induced tumors in C57BL/6J mice was significantly inhibited by the low dose of Doxorubicin in the presence of compound 1e as depicted by molecular and immunohistochemical analysis. Thus, the study suggests that EGFR inhibition-mediated sensitization of the aggressive and metastatic breast CSCs in TNBCs toward chemotherapeutics may reduce the relapse of the disease.

Erlotinib combination with a mitochondria-targeted ubiquinone effectively suppresses pancreatic cancer cell survival.

Pancreatic cancer is a leading cause of cancer-related deaths. Increased activity of the epidermal growth factor receptor (EGFR) is often observed in pancreatic cancer, and the small molecule EGFR inhibitor erlotinib has been approved for pancreatic cancer therapy by the food and drug administration. Nevertheless, erlotinib alone is ineffective and should be combined with other drugs to improve therapeutic outcomes. We previously showed that certain receptor tyrosine kinase inhibitors can increase mitochondrial membrane potential (Δψm), facilitate tumor cell uptake of Δψm-sensitive agents, disrupt mitochondrial homeostasis, and subsequently trigger tumor cell death. Erlotinib has not been tested for this effect. To determine whether erlotinib can elevate Δψm and increase tumor cell uptake of Δψm-sensitive agents, subsequently triggering tumor cell death. Δψm-sensitive fluorescent dye was used to determine how erlotinib affects Δψm in pancreatic adenocarcinoma (PDAC) cell lines. The viability of conventional and patient-derived primary PDAC cell lines in 2D- and 3D cultures was measured after treating cells sequentially with erlotinib and mitochondria-targeted ubiquinone (MitoQ), a Δψm-sensitive MitoQ. The synergy between erlotinib and MitoQ was then analyzed using SynergyFinder 2.0. The preclinical efficacy of the two-drug combination was determined using immune-compromised nude mice bearing PDAC cell line xenografts. Erlotinib elevated Δψm in PDAC cells, facilitating tumor cell uptake and mitochondrial enrichment of Δψm-sensitive agents. MitoQ triggered caspase-dependent apoptosis in PDAC cells in culture if used at high doses, while erlotinib pretreatment potentiated low doses of MitoQ. SynergyFinder suggested that these drugs synergistically induced tumor cell lethality. Consistent with in vitro data, erlotinib and MitoQ combination suppressed human PDAC cell line xenografts in mice more effectively than single treatments of each agent. Our findings suggest that a combination of erlotinib and MitoQ has the potential to suppress pancreatic tumor cell viability effectively.

Leveraging innate immunity with AFM24, a novel CD16A and epidermal growth factor receptor (EGFR) bispecific innate cell engager: Interim results for the non-small cell lung cancer (NSCLC) cohort.

2533 Background: Patients with EGFR mutant NSCLC who progress on or after small molecule EGFR inhibitors have only limited treatment options. AFM24 is a tetravalent, bispecific innate cell engager that binds EGFR on solid tumor cells and CD16A on NK cells to redirect and enhance antitumor antibody-dependent cellular cytotoxicity, thus acting independently of the EGFR downstream signaling pathway and EGFR expression levels. The Phase 1 dose escalation phase of the presented study (NCT04259450) established the recommended Phase 2 dose of AFM24 monotherapy at 480 mg based on tolerability, receptor occupancy, and pharmacokinetics (PK). Correlative science data revealed an activation and enrichment of immune cells in the tumor microenvironment. Methods: The Phase 2a expansion phase is evaluating 480 mg AFM24 in patients with EGFR mutant NSCLC, relapsed or refractory to ≥1 prior lines of therapy; EGFR-positivity is defined as positive staining for EGFR in ≥1% of tumor cells per local immunohistochemistry assay. The study follows Simon’s two-stage design. The primary endpoint is overall response rate per local RECIST v1.1; secondary endpoints include safety, PK, and immunogenicity. Efficacy per iRECIST is an exploratory endpoint. AFM24 is administered intravenously once weekly in a 28-day cycle. Tumor assessments are performed at initial screening, cycles 2, 4, 6, 8, and every 3 cycles thereafter. Results: As of December 2022, 14 patients (median [range] age 55 [37–82]; 12 male; 11 Asian, 3 White) were enrolled; the median number of prior therapies was 2.5 (1–12). Median treatment duration with AFM24 was 6.7 weeks (1.0–26.1). Best objective response in 10 evaluable patients was confirmed partial response in 1 patient (change from baseline –45%); 4 patients exhibited stable disease, 1 was confirmed. Tumor shrinkage occurred in 2 patients with stable disease (–6%, –18%). The tumor control rate was 50%. Treatment-related adverse events (TRAEs) were reported in 13 patients; infusion related reactions (IRRs, 12), dermatitis acneiform, neutrophil count decreased, decreased appetite, and myalgia (2 each) were most common. Grade ≥3 TRAEs occurred in 4 patients and included decreased neutrophil count (2), lymphopenia, and IRR (1 each). Grade 5 pneumonitis was observed in 1 patient with disease progression and multiple comorbidities; relation to AFM24 could not be ruled out. As of January 2023, enrollment is ongoing; results of the interim analysis will be presented. Conclusions: AFM24 demonstrated clinical activity and acceptable safety in heavily pretreated patients with EGFR mutant NSCLC. The novel mechanism of action of AFM24 could add to the therapeutic options for patients with EGFR expressing tumors and is under clinical evaluation as a single agent and in combination with atezolizumab or autologous NK cells. Clinical trial information: NCT04259450 .

Osimertinib Improves overall survival of EGFR-mutant NSCLC patients with leptomeningeal metastases

ObjectiveOsimertinib is a third-generation, irreversible, small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that can effectively penetrate the blood brain-barrier (BBB). This study mainly explored the factors affecting the prognosis of EGFR-mutant advanced non-small cell lung cancer (NSCLC) patients with leptomeningeal metastases (LM), and whether osimertinib could improve the survival benefit in these patients compared with those not treated with osimertinib. MethodsWe retrospectively analyzed patients who had been admitted with EGFR-mutant NSCLC and cytologically confirmed LM to the Peking Union Medical College Hospital between January 2013 and December 2019. Overall survival (OS) was defined as the primary outcome of interest. ResultsA total of 71 patients with LM were included in this analysis, with a median OS (mOS) of 10.7 months (95% CI [7.6, 13.8]). Among them, 39 patients were treated with osimertinib after LM while 32 patients were untreated. Patients treated with osimertinib had a mOS of 11.3 months (95%CI [0, 23.9]) compared with the untreated patients who had a mOS of 8.1 months (95%CI [2.9, 13.3]), with a significant difference between the groups (hazard ratio [HR]): 0.43, 95%CI:0.22–0.66, p = 0.0009). Multivariate analysis revealed the use of osimertinib were correlated with superior OS with a HR of 0.43 (95%CI [0.25, 0.75]), with a statistically significant difference (p = 0.003). ConclusionsOsimertinib can prolong the overall survival of EGFR-mutant NSCLC patients with LM and improve patient outcomes.

Pyrrole-based EGFR inhibitors for the treatment of NCSLC: Binding modes and SARs investigations.

The treatment of advanced non-small cell lung cancer (NSCLC) has made substantial progress due to the rapid development of small molecule targeted therapy, with dramatically prolonged survival. As an effective drug for the treatment of NSCLC, epidermal growth factor receptor (EGFR) inhibitors are currently experiencing issues like severe adverse events and drug resistance. It is urgent to develop novel types of EGFR inhibitors to overcome the abovementioned limitations. Pyrrole always works well as a probe for the creation of novel medication candidates for hard-to-treat conditions like lung cancer. Although the design, synthesis, and biological assays of pyrrole derivatives have been reported, their inhibitory actions against the receptor tyrosine kinase (RTK) EGFR have not been in-depthly studied. This review highlights the small molecule EGFR inhibitors containing pyrrole heterocyclic pharmacophores in recent years, and the research on their mechanism, biological activity, and structure-activity relationship (SAR).

Overexpression of Circular RNA circ_0013587 Reverses Erlotinib Resistance in Pancreatic Cancer Cells Through Regulating the miR-1227/E-Cadherin Pathway.

BackgroundErlotinib, a small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, demonstrated therapeutic efficacy against pancreatic cancer. However, acquired resistance to erlotinib in pancreatic cancer is widely observed, and the exact mechanisms have not been fully explored until now. We examined the role of circular RNA circ_0013587 in the acquired resistance to erlotinib in pancreatic cancer cells and explored the underlying mechanisms.MethodsWe selected erlotinib-resistant pancreatic cancer cells from the AsPC-1 cell line. The expression of circ_0013587 was examined by qRT-PCR assays. The effects of circ_0013587 on pancreatic cancer cell proliferation, invasion, and erlotinib resistance were assessed by cell functional assays. Bioinformatic analysis and dual-luciferase reporter assays identified circ_0013587 and E-cadherin as direct targets of miR-1227. Mouse xenograft models were employed to investigate the function of circ_0013587 in erlotinib resistance of tumors in vivo.ResultsCirc_0013587 expression was significantly reduced in erlotinib-resistant AsPC-1 cells. We found that increasing circ_0013587 levels in erlotinib-resistant AsPC-1 cells re-sensitized them, whereas reducing circ_0013587 levels in erlotinib-sensitive AsPC-1 cells made them resistant. Mechanically, circ_0013587 released E-cadherin from the suppression of miR-1227, leading to E-cadherin up-regulation. Rescue assays highlighted that circ_0013587 reversed erlotinib resistance in pancreatic cancer cells by increasing E-cadherin levels through reducing the expression of miR-1227. Furthermore, circ_0013587 overexpression sensitized erlotinib-resistant AsPC-1 cells to erlotinib in xenograft models.ConclusionsOur results demonstrated that down-regulation of circ_0013587 contributes to acquired resistance to erlotinib in pancreatic cancer cells through mediating the miR-1227/E-cadherin pathway and that circ_0013587 is a potential target molecular to overcome erlotinib resistance.

The pre-clinical discovery and development of osimertinib used to treat non-small cell lung cancer

ABSTRACT Introduction: Osimertinib is currently the only FDA- and EMA-approved third-generation small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). It was initially indicated for second-line treatment of patients with metastatic EGFR T790M mutation-positive non-small cell lung cancer (NSCLC) and got approved for first-line treatment of EGFR activation mutation-positive metastatic NSCLC in 2018. Most recently, the FDA granted approval for the adjuvant treatment of patients with early-stage mutated EGFR NSCLC after tumor resection. Areas covered: This drug discovery case history focuses on the key studies that led to the preclinical discovery and development of osimertinib. The authors focus on published preclinical studies by scientists from AstraZeneca and highlight key events in the clinical development. Expert opinion: Although eventually compromised by the cellular plasticity of the tumor and the inevitable acquisition of drug resistance through the use of osimertinib, its key role in the treatment of NSCLC with specific EGFR mutations will be maintained in the near future. As the genome of EGFR is highly labile and since the rapid development of new mutants remains an issue, there is still room for improvement for the next generation of inhibitors.

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

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

Discovery of potent epidermal growth factor receptor (EGFR) degraders by proteolysis targeting chimera (PROTAC)

Epidermal growth factor receptor (EGFR), a member of the HER family, is closely related to the development of multiple cancers. Herein, we report the discovery of small molecule EGFR degraders based on the proteolysis targeting chimera (PROTAC) strategy. In the present study, 13 EGFR degraders containing pyrido[3,4-d] pyrimidine moiety were designed and synthesized. Promising PROTACs 2 and 10 induced degradation of EGFR in HCC827 cells with the DC50 values of 45.2 and 34.8 nM, respectively. Cellular protein-controlling machinery ubiquitin proteasome system (UPS) was involved in the degradation process. Furthermore, the degraders 2 and 10 could significantly induce the apoptosis of HCC827 cells and arrest the cells in G1 phase. These findings demonstrated that compounds 2 and 10 could serve as effective EGFRdel19-targeting degraders in HCC827 cells. v.

Molecular Targeting Therapy against EGFR Family in Breast Cancer: Progress and Future Potentials.

The epidermal growth factor receptor (EGFR) family contains four transmembrane tyrosine kinases (EGFR1/ErbB1, Her2/ErbB2, Her3/ErbB3 and Her4/ErbB4) and 13 secreted polypeptide ligands. EGFRs are overexpressed in many solid tumors, including breast, pancreas, head-and-neck, prostate, ovarian, renal, colon, and non-small-cell lung cancer. Such overexpression produces strong stimulation of downstream signaling pathways, which induce cell growth, cell differentiation, cell cycle progression, angiogenesis, cell motility and blocking of apoptosis.The high expression and/or functional activation of EGFRs correlates with the pathogenesis and progression of several cancers, which make them attractive targets for both diagnosis and therapy. Several approaches have been developed to target these receptors and/or the EGFR modulated effects in cancer cells. Most approaches include the development of anti-EGFRs antibodies and/or small-molecule EGFR inhibitors. This review presents the state-of-the-art and future prospects of targeting EGFRs to treat breast cancer.

DDIS-17. DEVELOPMENT OF BRAIN-PENETRANT EGFR INHIBITORS FOR CNS MALIGNANCIES

Abstract The epidermal growth factor receptor (EGFR) is altered in nearly 60% of glioblastoma (GBM) tumors, however, EGFR tyrosine kinase inhibitors (TKIs) have failed to improve outcomes for patients with GBM. This can be attributed to the inability of clinically available EGFR TKIs (e.g., erlotinib, gefitinib, lapatinib, afatinib, cetuximab) to effectively cross the blood-brain-barrier (BBB) and reach adequate pharmacological levels for a tumor response. Herein, we performed a structure-activity relationship (SAR) to obtain EGFR TKIs with both high brain penetrance and potency against EGFR-activated GBM cells. From over 80 novel compounds synthesized, our lead EGFR TKI—JCN068—exhibited exceptional BBB penetration (350% brain to plasma) while also having optimal ADME properties (60% oral bioavailability, ~5 hr half-life, >100 µg/mL solubility, etc). Moreover, JCN068 demonstrated picomolar potency against purified EGFR kinase, 1000-fold selectivity for EGFR relative to other kinases, and nanomolar activity against EGFR-altered, GBM patient-derived cells in culture. Importantly, JCN068 demonstrated superior efficacy—with negligible toxicity—compared to clinically available small molecule EGFR TKIs (erlotinib and lapatinib) against multiple EGFR-altered patient-derived orthotopic GBM xenografts. Due to these excellent drug-like properties, JCN068 is currently progressing towards clinical development for EGFR-activated GBM patients.

Abstract 1732: Switch to MET oncogene dependence as a novel mechanism of drug resistance in EGFR-mutant lung cancer

Abstract Introduction: Non-small cell lung cancers harboring sensitizing gain-of-function mutations in the epidermal growth factor receptor (EGFR) are treated with small molecule EGFR kinase inhibitors including erlotinib and osimertinib. Unfortunately, the clinical efficacy of these inhibitors is limited by progression to drug resistance. Genomic amplification of the hepatocyte growth factor receptor (MET) is a prevalent mechanism of resistance to clinical EGFR inhibitors. EGFR mutant lung cancers with MET amplification are co-dependent on signaling through EGFR and MET kinases, whereby either oncogene can phosphorylate the EGFR family receptor ERBB3, activating downstream signaling and promoting survival. These EGFR/MET co-dependent cancers are characteristically resistant to treatment with individual drugs, but retain sensitivity to combination treatment with EGFR and MET inhibitors. Here, we describe three patient-derived EGFR mutant, MET amplified lung cancer models that exhibit a switch away from EGFR, to MET oncogene dependence. Methods: We established and characterized patient-derived lung cancer cell lines and xenograft models harboring concurrent EGFR activating mutations (EGFR L858R or EGFR Del19) and genomic MET copy number gain. Three patient-derived models—DFCI81, DFCI161, and DFCI307—were developed from pleural effusion and core biopsy specimens of patients whose tumors progressed on erlotinib. Clinical samples were immediately sorted and stably cultured in vitro or engrafted into immunodeficient mice. Results: DFCI81, DFCI161, and DFCI307 cell lines and xenograft models retained mutant EGFR expression, but exhibited resistance to clinical EGFR inhibitors and sensitivity to single-agent c-MET inhibitors, including crizotinib and savolitinib. Comparing our EGFR-mutant and MET-dependent cell lines to EGFR/MET-codependent models, we observed that EGFR expression was significantly reduced in our models compared to controls. Ectopic overexpression of EGFR Del19 and EGFR L858R in DFCI81 and DFCI161 cell lines, respectively, was sufficient to confer crizotinib resistance and induce EGFR/MET co-dependency. We demonstrated that MET-mediated ERBB3 phosphorylation drives downstream PI3K activation to promote cell proliferation and survival in DFCI81 and DFCI161 cells. In these contexts, ERBB3 reactivation by recombinant ligand treatment was sufficient to induce EGFR-mediated ERBB3 activation, conferring resistance to single-agent crizotinib treatment. Conclusions: We have identified and characterized three patient-derived models of treatment refractory EGFR mutant lung cancer that exhibit a switch to MET oncogene dependency. Clinically, we predict a subset of EGFR mutant, MET-dependent tumors exists, and can be identified de novo by a reduced EGFR to MET expression ratio: a potential biomarker predictive of sensitivity to single-agent MET inhibition. Citation Format: Pinar Ö. Eser, Raymond M. Paranal, Michael J. Poitras, Man Xu, Stephen Wang, Atsuko Ogino, Jihyun Choi, Pavlos Missios, Heidi M. Haikala, Jieun Son, Mika Lin, Masahiko Yanagita, Prafulla C. Gokhale, George Q. Daley, Pasi A. Jänne. Switch to MET oncogene dependence as a novel mechanism of drug resistance in EGFR-mutant lung cancer [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 1732.

Inhibition of Epidermal Growth Factor Receptor (EGFR) Reduces Lipopolysaccharide (LPS)-Induced Activation and Inflammatory Cytokines in Hepatic Stellate Cells In Vitro.

BackgroundEpidermal growth factor receptor (EGFR) expression is associated with hepatic fibrogenesis. Activated hepatic stellate cells (HSCs) release inflammatory cytokines and extracellular matrix (ECM). The aim of this in vitro study was to investigate HSCs, activated by lipopolysaccharide (LPS), and the role of EGFR using the small molecule EGFR inhibitor, AG1478, and using knockdown of the EGFR gene using small interfering RNA (siRNA) cell transfection.Material/MethodsHSCs, isolated from male Sprague-Dawley rats, were cultured and treated with and without LPS (100 ng/mL), with and without AG1478 (2.5 μM and 5.0 μM) Cell survival and proliferation were studied using an MTT assay. Western blot was used to measure levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IκBα, cytoplasm and nuclear NFκB and EGFR in the cell lysates before and after small interfering RNA (siRNA) transfection. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to measure the mRNA levels of transforming growth factor (TGF)-β, Col-1, and α-smooth muscle actin (SMA). The Toll-like receptor 4 (TLR4) antagonist TAK-242 and the selective c-Src inhibitor, PP2 in LPS induced-EGFR phosphorylation was evaluated using Western blot.ResultsInhibition of EGFR decreased LPS-induced HSC proliferation and inflammatory cytokines. The TLR4 antagonist TAK-242, and the c-Src inhibitor, PP2 reduced EGFR activation of HSCs, indicating a possible role for the TLR4/c-Src signaling cascade in LPS-induced HSC activation.ConclusionsActivation of HSCs by LPS in vitro, including the expression of inflammatory cytokines and mediators of fibrogenesis, were shown to be dependent on the expression of EGFR.

The Influence of EGFR Inactivation on the Radiation Response in High Grade Glioma.

Lack of effectiveness of radiation therapy may arise from different factors such as radiation induced receptor tyrosine kinase activation and cell repopulation; cell capability to repair radiation induced DNA damage; high grade glioma (HGG) tumous heterogeneity, etc. In this study, we analyzed the potential of targeting epidermal growth factor receptor (EGFR) in inducing radiosensitivity in two human HGG cell lines (11 and 15) that displayed similar growth patterns and expressed the receptor protein at the cell surface. We found that 15 HGG cells that express more EGFR at the cell surface were more sensitive to AG556 (an EGFR inhibitor), compared to 11 HGG cells. Although in line 15 the effect of the inhibitor was greater than in line 11, it should be noted that the efficacy of this small-molecule EGFR inhibitor as monotherapy in both cell lines has been modest, at best. Our data showed a slight difference in the response to radiation of the HGG cell lines, three days after the treatment, with line 15 responding better than line 11. However, both cell lines responded to ionizing radiation in the same way, seven days after irradiation. EGFR inhibition induced radiosensitivity in 11 HGG cells, while, in 15 HGG cells, the effect of AG556 treatment on radiation response was almost nonexistent.

Recent Progress of Small-Molecule Epidermal Growth Factor Receptor (EGFR) Inhibitors against C797S Resistance in Non-Small-Cell Lung Cancer.

The epidermal growth factor receptor (EGFR) has been a particular interest for drug development for treatment of non-small-cell lung cancer (NSCLC). The current third-generation EGFR small-molecule inhibitors, especially osimertinib, are at the forefront clinically for treatment of patients with NSCLC. However, a high percentage of these treated patients developed a tertiary cystein-797 to serine-790 (C797S) mutation in the EGFR kinase domain. This C797S mutation is thought to induce resistance to all current irreversible EGFR TKIs. In this Miniperspective, we present key mechanisms of resistance in response to third-generation EGFR TKIs, and emerging reports on novel EGFR TKIs to combat the resistance. Specifically, we analyze the allosteric and ATP-competitive inhibitors in terms of drug discovery, binding mechanism, and their potency and selectivity against EGFR harboring C797S mutations. Lastly, we provide some perspectives on new challenges and future directions in this field.

Cancer combination therapy of the sesquiterpenoid artesunate and the selective EGFR-tyrosine kinase inhibitor erlotinib

BackgroundThe shift from cytotoxic to targeted chemotherapy led to improved treatment outcomes in oncology. Nevertheless, many cancer patients cannot be cured from their disease because of the development of drug resistance and side effects. PurposeThere is an ongoing quest for novel compounds, which raised not only the interest in natural products but also in novel combination therapy regimens. Study designIn this review, we report on the inhibition epidermal growth factor receptor (EGFR) by targeted small molecules and their combination with natural products from medicinal plants. ResultsThe combination of erlotinib with artesunate leads to synergistic inhibition of cell growth in isobologram analyses. Artesunate is an approved anti-malaria drug, which is also active against cancer as shown in vitro, in vivo and in preliminary clinical phase I/II trials. ConclusionThe combination of natural products (e.g. the sesquiterpenoid artesunate) and synthetic compounds (e.g. the small molecule EGFR tyrosine kinase inhibitor erlotinib) may lead to improved clinical success rates in oncology.

SKLB188 inhibits the growth of head and neck squamous cell carcinoma by suppressing EGFR signalling

Background:Overexpression of epidermal growth factor receptor (EGFR) occurs in approximately 90% of head and neck squamous cell carcinoma (HNSCC), and is correlated with poor prognosis. Thus, targeting EGFR is a promising strategy for treatment of HNSCC. Several small molecule EGFR inhibitors have been tested in clinical trials for treatment of HNSCC, but none of them are more effective than the current chemotherapeutic drugs. Thus, it is urgently needed to develop novel EGFR inhibitors for HNSCC treatment.Methods:By screening an in-house focused library containing approximately 650 000 known kinase inhibitors and kinase inhibitor-like compounds containing common kinase inhibitor core scaffolds, we identified SKLB188 as a lead compound for inhibition of EGFR. The anticancer effects of SKLB188 on HNSCC cells were investigated by in vitro cell growth, cell cycle and apoptosis assays, as well as in vivo FaDu xenograft mouse model. Molecular docking, in vitro kinase profiling and western blotting were performed to characterise EGFR as the molecular target.Results:SKLB188 inhibited HNSCC cell proliferation by inducing G1 cell cycle arrest, which was associated with downregulating the expression of Cdc25A, cyclins D1/A and cyclin-dependent kinases (CDK2/4), and upregulating the expression of cyclin-dependent kinase (CDK) inhibitors (p21Cip1 and p27Kip1), leading to decreased phosphorylation of Rb. SKLB188 also induced caspase-dependent apoptosis of HNSCC cells by downregulating the expression of Mcl-1 and survivin. Molecular docking revealed that SKLB188 could bind to the kinase domain of EGFR through hydrogen bonds and hydrophobic interactions. In vitro kinase assay showed that SKLB188 inhibited the activity of a recombinant human EGFR very potently (IC50=5 nM). Western blot analysis demonstrated that SKLB188 inhibited the phosphorylation of EGFR and its downstream targets, extracellular signal-regulated protein kinases 1 and 2 (Erk1/2) and Akt in the cells. In addition, SKLB188 dose-dependently inhibited FaDu xenograft growth in nude mice, and concurrently inhibited the phosphorylation of Erk1/2 and Akt in the tumours.Conclusions:SKLB188 potently inhibits the growth of HNSCC cells in vitro and in vivo by targeting EGFR signalling. The results provide a basis for further clinical investigation of SKLB188 as a targeted therapy for HNSCC. Our findings may open a new avenue for development of novel EGFR inhibitors for treatment of HNSCC and other cancers.

4-Anilinoquinazoline Derivatives with Epidermal Growth Factor Receptor Inhibitor Activity.

4-Anilinoquinazoline derivatives possess high anti-cancer activities. Many of them are highly selective tyrosine kinase inhibitors (TKI), particularly against epidermal growth factor receptor (EGFR). EGFRs are overexpressed or mutated in most carcinomas and are required for tumor progression. The efficacy of EGFR-targeted anti-tumor drugs is impaired by drug-induced acquired resistance. Therefore, there is urgency to find better anti-cancer agents with novel effects on EGFR. 4-Anilinoquinazolines are small molecule EGFR inhibitors that have been synthesized and assessed for their anti-tumor bioactivity. In this paper, we review the 4-anilinoquinazoline derivatives with EGFR inhibitor activity reported in recent years.

Three generations of epidermal growth factor receptor tyrosine kinase inhibitors developed to revolutionize the therapy of lung cancer.

Lung cancer, ~80%–85% of which is non-small-cell lung cancer (NSCLC), is the leading cause of cancer-related mortality worldwide. Sensitizing mutations in epidermal growth factor receptor (EGFR) gene (EGFRm+), such as exon 19 deletions and exon 21 L858R point mutations, are the most important drivers in NSCLC patients. In this respect, small-molecule EGFR tyrosine kinase inhibitors (TKIs) have been designed and developed, which launched the era of targeted, personalized and precise medicine for lung cancer. Patients with EGFRm+ could achieve good responses to the treatment with the first-generation EGFR TKIs, such as erlotinib and gefitinib. However, most patients develop acquired drug resistance mostly driven by the T790M mutation occurring within exon 20. Although the second-generation EGFR TKIs, such as afatinib, dacomitinib and neratinib, demonstrated promising activity against T790M in preclinical models, they have failed to overcome resistance in patients due to dose-limiting toxicity. Recently, the third-generation EGFR TKIs have shown to be effective against cell lines and murine models harboring T790M mutations while sparing wild-type EGFR, which represents a promising breakthrough approach in overcoming T790M-mediated resistance in NSCLC patients. This article provides a comprehensive review of the therapy revolution for NSCLC with three generations of EGFR TKIs.