Targeting the Epidermal Growth Factor Receptor with Molecular Degraders: State-of-the-Art and Future Opportunities

Design, synthesis and biological evaluation of a new series of imidazothiazole-hydrazone hybrids as dual EGFR and Akt inhibitors for NSCLC therapy

In search of small molecules for targeted therapy of non-small cell lung carcinoma (NSCLC), an efficient four-step synthetic route was followed for the synthesis of new imidazothiazole-hydrazone hybrids, which were assessed for their cytotoxic effects on human lung adenocarcinoma (A549) and human lung fibroblast (CCD-19Lu) cells. Among them, compounds 4, 6, 13, 16, 17 and 21 exhibited selective cytotoxic activity against A549 cell line. In vitro mechanistic studies were performed to assess their effects on apoptosis, caspase-3, cell cycle, EGFR and Akt in A549 cells. Compounds 6, 16, 17 and 21 promoted apoptotic cell death more than erlotinib. According to the in vitro data, it is quite clear that compound 6 promotes apoptosis through caspase-3 activation and arrests the cell cycle at the G0/G1 phase in A549 cells. Compounds 16 and 17 arrested the cell cycle at the S phase, whereas compounds 4, 13 and 21 caused the cell cycle arrest at the G2/M phase. The most effective EGFR inhibitor in this series was found as compound 13, followed by compounds 17 and 16. Furthermore, Akt inhibitory effects of compounds 16 and 17 in A549 cells were close to that of GSK690693. In particular, it can be concluded that the cytotoxic and apoptotic effects of compounds 16 and 17 are associated with their inhibitory effects on both EGFR and Akt. Molecular docking studies suggest that compounds 16 and 17 interact with crucial amino acid residues in the binding sites of human EGFR (PDB ID: 1M17) and Akt2 (PDB ID: 3D0E). Based on the in silico data, both compounds are predicted to possess favorable oral bioavailability and drug-likeness. Further studies are required to benefit from these compounds as anticancer agents for targeted therapy of NSCLC.

Exploring the potential mechanism of ginsenoside Rg1 to regulate ferroptosis in Alzheimer's disease based on network pharmacology

OBJECTIVES

To explore the pathogenesis of Alzheimer's disease (AD), the potential targets and signaling pathways of ginsenoside Rg1 against AD were investigated by network pharmacology.

METHODS

Ginsenoside Rg1 targets were identified through PubChem, PharmMapper, and Uniprot databases, while the GeneCards database was used to examine the respective targets of amyloid precursor protein (APP) and AD. Then, the common targets between ginsenoside Rg1 and APP were explored by the Venny tool, the interaction network diagram between the active components and the targets was built via Cytoscape software, as well as GO enrichment and KEGG pathway annotation analysis were performed. Furthermore, genes associated with ferroptosis were found by the GeneCards and FerrDb databases. Besides, the connection among ginsenoside Rg1, APP, ferroptosis, and AD was predicted and analyzed. Finally, the effects of ginsenosides Rg1 and liproxstain-1 on the proliferation and differentiation of APP/PS1 mice were evaluated by immunohistochemistry.

RESULTS

Ginsenoside Rg1, APP, ferroptosis, and AD had 12 hub genes. GO enrichment and KEGG pathway annotation analysis showed that EGFR, SRC, protein hydrolysis, protein phosphorylation, the Relaxin pathway, and the FoxO signaling pathway play an important role in the potential mechanism of ginsenoside Rg1's under regulation of ferroptosis anti-AD through the modulation of APP-related signaling pathways. The APP/PS1 mice experiment verified that ginsenosides Rg1 and liproxstain-1 can promote the proliferation and differentiation.

CONCLUSION

Ginsenoside Rg1, APP and ferroptosis may act on EGFR, SRC, the Relaxin and FoxO signaling pathways to regulate protein metabolism, protein phosphorylation and other pathways to improve AD symptoms.

Design, synthesis, and anticancer assessment of structural analogues of (E)-1-((3,4,5-trimethoxybenzylidene)amino)-4-(3,4,5-trimethoxyphenyl)imidazo[1,2-a]quinoxaline-2-carbonitrile (6b), an imidazo[1,2-a]quinoxaline-based non-covalent EGFR inhibitor

In our quest to find improved anticancer therapeutics, we expedite the lead optimization of (E)-1-((3,4,5-trimethoxybenzylidene)amino)-4-(3,4,5-trimethoxyphenyl)imidazo[1,2-a]quinoxaline-2-carbonitrile (6b), an EGFR inhibitor previously discovered in our laboratory through an in-house screening program. The lead optimization was rationally initiated considering the catalytic site of EGFR. We synthesized twenty-nine new analogues of 6b and assessed their anticancer activities. SAR studies highlighted the role of important groups in controlling anticancer activities. Among all, 5a and 5l were found to exhibit improved EGFR inhibition with anticancer asset potential. In silico studies corroborated with in vitro EGFR inhibitory results. The deeper analysis of 5a and 5l revealed that these synthetics could alter the MMP (ΔΨ m) and significantly reduce the ROS levels in lung cancer cells. This is a vital prerequisite for better plausible EGFR inhibitors devoid of cardiotoxicity. qPCR analysis further revealed that the investigational compounds 5a and 5l were able to downregulate the expression of key oncogenes, viz., KRAS, MAP2K, and EGFR. The downregulation of these genes suggests that the investigational compounds could interact and inhibit key players in the signalling cascade along with the EGFR, which may lead to the inhibition of the growth and prognosis of cancer cells via a holistic approach.

Exploring the structural activity relationship of the Osimertinib: A covalent inhibitor of double mutant EGFRL858R/T790M tyrosine kinase for the treatment of Non-Small Cell Lung Cancer (NSCLC)

The USFDA granted regular approval to Osimertinib (AZD9291) on March 2017, for treating individuals with metastatic Non-Small Cell Lung Cancer having EGFR T790M mutation. Clinically, Osimertinib stands at the forefront for the treatment of patients with Non-Small Cell Lung Cancer. Osimertinib forms a covalent bond with the Cys797 residue and predominantly spares binding to WT-EGFR, thereby reducing toxicity and enabling the administration of doses that effectively inhibit T790M. However, a high percentage of patients treated with Osimertinib (AZD9291) developed a tertiary cysteine797 to serine797 (C797S) mutation in the EGFR kinase domain, rendering resistance to it. This comprehensive review sheds light on the chemistry, computational aspects, structural features, and expansive spectrum of biological activities of Osimertinib and its analogues. The in-depth exploration of these facets serves as a valuable resource for medicinal chemists, empowering them to design better Osimertinib analogues. This exhaustive study not only provides insights into improving potency but also emphasizes considerations for mutant selectivity and optimizing pharmacokinetic properties. This review acts as a guiding beacon for the strategic design and development of next-generation Osimertinib analogues.

Design, Synthesis, and Biological Evaluation of Novel EGFR PROTACs Targeting C797S Mutation

The epidermal growth factor receptor (EGFR) tertiary C797S mutation is an important cause of resistance to Osimertinib, which seriously hinders the clinical application of Osimertinib. Developing proteolysis-targeting chimeras (PROTACs) targeting EGFR mutants can offer a promising strategy to overcome drug resistance. In this study, some novel PROTACs targeting C797S mutation were designed and synthesized based on a new EGFR inhibitor and displayed a potent degradation effect in H1975-TM cells harboring EGFRL858R/T790M/C797S. The representative compound C6 exhibited a DC50 of 10.2 nM against EGFRL858R/T790M/C797S and an IC50 of 10.3 nM against H1975-TM. Furthermore, C6 also showed potent degradation activity against various main EGFR mutants, including EGFRDel19/T790M/C797S. Mechanistic studies revealed that the protein degradation was achieved through the ubiquitin-proteasome system. Finally, C6 inhibited tumor growth in the H1975-TM xenograft tumor model effectively and safely. This study identifies a novel and potent EGFR PROTAC to overcome Osimertinib resistance mediated by C797S mutation.

A partial epithelial-mesenchymal transition signature for highly aggressive colorectal cancer cells that survive under nutrient restriction

Partial epithelial-mesenchymal transition (p-EMT) has recently been identified as a hybrid state consisting of cells with both epithelial and mesenchymal characteristics and is associated with the migration, metastasis, and chemoresistance of cancer cells. Here, we describe the induction of p-EMT in starved colorectal cancer (CRC) cells and identify a p-EMT gene signature that can predict prognosis. Functional characterisation of starvation-induced p-EMT in HCT116, DLD1, and HT29 cells showed changes in proliferation, morphology, and drug sensitivity, supported by in vivo studies using the chorioallantoic membrane model. An EMT-specific quantitative polymerase chain reaction (qPCR) array was used to screen for deregulated genes, leading to the establishment of an in silico gene signature that was correlated with poor disease-free survival in CRC patients along with the CRC consensus molecular subtype CMS4. Among the significantly deregulated p-EMT genes, a triple-gene signature consisting of SERPINE1, SOX10, and epidermal growth factor receptor (EGFR) was identified. Starvation-induced p-EMT was characterised by increased migratory potential and chemoresistance, as well as E-cadherin processing and internalisation. Both gene signature and E-cadherin alterations could be reversed by the proteasomal inhibitor MG132. Spatially resolving EGFR expression with high-resolution immunofluorescence imaging identified a proliferation stop in starved CRC cells caused by EGFR internalisation. In conclusion, we have gained insight into a previously undiscovered EMT mechanism that may become relevant when tumour cells are under nutrient stress, as seen in early stages of metastasis. Targeting this process of tumour cell dissemination might help to prevent EMT and overcome drug resistance. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Discovery of Potent SOS1 PROTACs with Effective Antitumor Activities against NCI-H358 Tumor Cells In Vitro/In Vivo

Directly targeted KRAS inhibitors are now facing resistance problems, which might be partially solved by the combination of SOS1 inhibitors with KRAS inhibitors. However, this combination may still have some resistance mitigation potential. Comparatively, SOS1 PROTAC may have promising applications in addressing the drug resistance problem by degrading the SOS1 protein. Herein, we report the discovery of novel SOS1 PROTACs and their antitumor activity both in vitro and in vivo. In vitro studies demonstrated that degrader 4 had strong inhibitory effects on the proliferation of NCI-H358 cells with IC50 of 5 nM, together with significant degradation of SOS1 protein with DC50 of 13 nM. In the NCI-H358 xenograft model, degrader 4 exhibited significant antitumor activities with TGITV values of 58.8% at 30 mg/kg bid. The PK and safety profiles also supported degrader 4 for further studies as an effective tool compound.

Targeted Strategies for Degradation of Key Transmembrane Proteins in Cancer

Targeted protein degradation is an attractive technology for cancer treatment due to its ability to overcome the unpredictability of the small molecule inhibitors that cause resistance mutations. In recent years, various targeted protein degradation strategies have been developed based on the ubiquitin-proteasome system in the cytoplasm or the autophagy-lysosomal system during endocytosis. In this review, we describe and compare technologies for the targeted inhibition and targeted degradation of the epidermal growth factor receptor (EGFR), one of the major proteins responsible for the onset and progression of many types of cancer. In addition, we develop an alternative strategy, called alloAUTO, based on the binding of new heterocyclic compounds to an allosteric site located in close proximity to the EGFR catalytic site. These compounds cause the targeted degradation of the transmembrane receptor, simultaneously activating both systems of protein degradation in cells. Damage to the EGFR signaling pathways promotes the inactivation of Bim sensor protein phosphorylation, which leads to the disintegration of the cytoskeleton, followed by the detachment of cancer cells from the extracellular matrix, and, ultimately, to cancer cell death. This hallmark of targeted cancer cell death suggests an advantage over other targeted protein degradation strategies, namely, the fewer cancer cells that survive mean fewer chemotherapy-resistant mutants appear.

Epidermal growth factor receptor PROTACs as an effective strategy for cancer therapy: A review

Epidermal growth factor receptor (EGFR), a transmembrane glycoprotein that mediates cellular signaling pathways involved in cell proliferation, angiogenesis, apoptosis, and metastatic spread, is an important oncogenic drug target. Targeting the intracellular and extracellular domains of the EGFR has been authorized for a number of small-molecule TKIs and mAbs, respectively. However, their clinical application is limited by EGFR catalytic structural domain alterations, cancer heterogeneity, and persistent drug resistance. To bypass these limitations, protease-targeted chimeras (PROTACs) are emerging as an emerging and promising anti-EGFR therapy. PROTACs compensate for the limitations of traditional occupancy-driven small molecules by exploiting intracellular protein destruction processes. Recently, a mushrooming number of heterobifunctional EGFR PROTACs have been created using wild-type (WT) and mutated EGFR TKIs. PROTACs outperformed EGFR TKIs in terms of cellular inhibition, potency, toxicity profiles, and anti-drug resistance. Herein, we present a comprehensive overview of the development of PROTACs targeting EGFR for cancer therapy, while also highlighting the challenges and opportunities associated with the field.

The next generation of EGFR inhibitors: a patenting perspective of PROTACs based EGFR degraders

INTRODUCTION

Abnormal expression of epidermal growth factor receptor (EGFR) contributes to tumor development, especially in non-small cell lung cancer (NSCLC). Although multiple inhibitors have been developed to target diverse EGFR mutations and several have been approved, the inevitable drug resistance and side effect remain a challenge, which motivates novel strategies. Proteolysis-targeting chimeras (PROTACs) have been gaining momentum for their potential as novel therapeutics for human diseases by triggering protein degradation. To date, various potent and specific EGFR PROTACs have been discovered and some of them have entered clinical trials.

AREAS COVERED

This review provides an overview of EGFR degraders in patents from 2016 to 2022. It provides an update of the discovery strategies, chemical structures, and molecular profiling of all available EGFR PROTACs. SciFinder, PubMed, Web of Science, EPO, and CNIPA databases were used for searching the literature and patents for EGFR PROTACs.

EXPERT OPINION

By employing the PROTAC technology, highly potent and selective EGFR degraders based on four generation EGFR inhibitors have been developed, which offer a new strategy to target EGFR mutations and overcome the drug resistance. Despite the satisfactory result in vitro and in vivo studies, their therapeutic value awaits more rigorous preclinical testing and clinical investigation.