HJM-561, a potent, selective and orally bioavailable EGFR PROTAC that overcomes osimertinib-resistant EGFR triple mutations

Taxus chinensis var. mairei (Lemée et Lévl) Cheng et L.K. Fu overcomes the resistance to osimertinib in EGFR-mutant non-small-cell lung cancer via suppression of ERK1/2-related cholesterol biosynthesis

ETHNOPHARMACOLOGICAL RELEVANCE

Acquired resistance to osimertinib limits its clinical efficacy in non-small cell lung cancer (NSCLC) with EGFR mutations. The widespread recognition of Taxus chinensis var. Mairei (Lemée et Lévl) Cheng et L.K. Fu (Chinese yew) as a natural anti-cancer medication is well-established. However, the specific contribution of Taxus chinensis var. Mairei (Lemée et Lévl) Cheng et L.K. Fu in addressing resistance to osimertinib is still uncertain.

AIM OF THE STUDY

Based on the biological behaviors and lipid metabolism, we investigated whether aqueous extract of Taxus chinensis var. Mairei (Lemée et Lévl) Cheng et L.K. Fu (AETC) could enhance the antitumor effect of osimertinib in NSCLC with an investigation on the precise mechanisms.

MATERIALS AND METHODS

The effect of AETC on enhancing osimertinib sensitivity was assessed via cell viability measurements, levels of reactive oxygen species (ROS), apoptosis, and lipid levels. Western blotting was used to verify the mechanisms of AETC responsible for overcoming the resistance to osimertinib via ERK1/2 overexpression and knockdown models. In vivo validation was conducted using subcutaneous xenografts from osimertinib-resistant cells in nude mice.

RESULTS

Osimertinib-resistant cells exhibited altered cholesterol biosynthesis, which was induced by ERK1/2 activation. The combination of AETC and osimertinib can synergistically decrease the levels of ROS in cells, enhance apoptosis, and inhibit the growth of osimertinib-resistant cells. Mechanistic experiments demonstrated that AETC can downregulate the key regulators of cholesterol biosynthesis by regulating ERK1/2, inhibiting the endogenous synthesis rate of cholesterol, and suppressing the level of lipids in osimertinib-resistant cells and xenograft tumors when combined with osimertinib, ultimately reversing resistance to osimertinib.

CONCLUSIONS

The resistance to osimertinib is significantly influenced by cholesterol biosynthesis, highlighting its pivotal role in this context. AETC can enhance osimertinib sensitivity via ERK/SREBP-2/HMGCR-mediated cholesterol biosynthesis. These results provide a promising therapeutic target and potential treatment option for resistance to osimertinib.

Discovery of new cyclopropane sulfonamide derivatives as EGFR inhibitors to overcome C797S-mediated resistance and EGFR double mutation

The C797S mutation of EGFR leads to Osimertinib resistance by blocking the covalent binding of Cys797. To develop new agents that can overcome EGFR mutation resistance, thirty seven new cyclopropane sulfonamide derivatives were synthesized and evaluated as EGFRL858R/T790M/C797S or EGFRDel19/T790M/C797S inhibitors by structure-based screening. Most of the synthesized compounds exhibit good to excellent anti proliferation activity against to BaF3-EGFR L858R/T790M/C797S and BaF3-C797S/Del19/T790M cancer cell lines. Representative compounds 8l showed inhibitory activity against the two cancer cell lines with the IC50 values of 0.0012 and 0.0013 μM, respectively. Another compound 8h, exhibited slightly lower activity (0.0042 and 0.0034 μM of the IC50 values) to both of the two tri-mutation cell lines, but excellent activities against H1975 and PC9 cells with IC50 values of 13 and 19 nM, respectively. Considering the acquired drug resistance of tumors is a gradual process, we chose 8h for further in vivo and mechanism study. 8h was demonstrated significantly inhibited tumor growth with 72.1 % of the TGI in the BaF3/EGFR-TM xenograft tumor model and 83.5 % in the H1975-DM xenograft tumor model. Compound 8h was confirmed to be safe with no significant side effects as showed by the results of in vitro assay of human normal cells and the sections of animals major organs. Mechanism studies showed that in addition to inhibiting EGFR mutations, 8h can also target the tumor microenvironment and induce tumor cell apoptosis. All these results indicate that 8h deserves further investigation as an EGFR inhibitor to overcome C797S-mediated resistance.

Mechanisms of resistance to tyrosine kinase inhibitor-targeted therapy and overcoming strategies

Tyrosine kinase inhibitor (TKI)-targeted therapy has revolutionized cancer treatment by selectively blocking specific signaling pathways crucial for tumor growth, offering improved outcomes with fewer side effects compared with conventional chemotherapy. However, despite their initial effectiveness, resistance to TKIs remains a significant challenge in clinical practice. Understanding the mechanisms underlying TKI resistance is paramount for improving patient outcomes and developing more effective treatment strategies. In this review, we explored various mechanisms contributing to TKI resistance, including on-target mechanisms and off-target mechanisms, as well as changes in the tumor histology and tumor microenvironment (intrinsic mechanisms). Additionally, we summarized current therapeutic approaches aiming at circumventing TKI resistance, including the development of next-generation TKIs and combination therapies. We also discussed emerging strategies such as the use of dual-targeted antibodies and PROteolysis Targeting Chimeras. Furthermore, we explored future directions in TKI-targeted therapy, including the methods for detecting and monitoring drug resistance during treatment, identification of novel targets, exploration of dual-acting kinase inhibitors, application of nanotechnologies in targeted therapy, and so on. Overall, this review provides a comprehensive overview of the challenges and opportunities in TKI-targeted therapy, aiming to advance our understanding of resistance mechanisms and guide the development of more effective therapeutic approaches in cancer treatment.

Discovery of a first-in-class protein degrader for the c-ros oncogene 1 (ROS1)

The c-ros oncogene 1 (ROS1), an oncogenic driver, is known to induce non-small cell lung cancer (NSCLC) when overactivated, particularly through the formation of fusion proteins. Traditional targeted therapies focus on inhibiting ROS1 activity with ROS 1 inhibitors to manage cancer progression. However, a new strategy involving the design of protein degraders offers a more potent approach by completely degrading ROS1 fusion oncoproteins, thereby effectively blocking their kinase activity and enhancing anti-tumour potential. Utilizing PROteolysis-TArgeting Chimera (PROTAC) technology and informed by molecular docking and rational design, we report the first ROS1-specific PROTAC, SIAIS039. This degrader effectively targets multiple ROS1 fusion oncoproteins (CD74-ROS1, SDC4-ROS1 and SLC34A2-ROS1) in engineered Ba/F3 cells and HCC78 cells, demonstrating anti-tumour effects against ROS1 fusion-driven cancer cells. It suppresses cell proliferation, induces cell cycle arrest, and apoptosis, and inhibits clonogenicity. The anti-tumour efficacy of SIAIS039 surpasses two approved drugs, crizotinib and entrectinib, and matches that of the top inhibitors, including lorlatinib and taletrectinib. Mechanistic studies confirm that the degradation induced by 039 requires the participation of ROS1 ligands and E3 ubiquitin ligases, and involves the proteasome and ubiquitination. In addition, 039 exhibited excellent oral bioavailability in a mouse xenograft model, highlighting its potential for clinical application. In conclusion, our study presents a promising and novel therapeutic strategy for ROS1 fusion-positive NSCLC by targeting ROS1 fusion oncoproteins for degradation, laying the foundation for the development of further PROTAC and offering hope for patients with ROS1 fusion-positive NSCLC.

Targeting EGFR with molecular degraders as a promising strategy to overcome resistance to EGFR inhibitors

Abnormal activation of EGFR is often associated with various malignant tumors, making it an important target for antitumor therapy. However, traditional targeted inhibitors have several limitations, such as drug resistance and side effects. Many studies have focused on the development of EGFR degraders to overcome this resistance and enhance the therapeutic effect on tumors. Proteolysis targeting chimeras (PROTAC) and Lysosome-based degradation techniques have made significant progress in degrading EGFR. This review provides a summary of the structural and function of EGFR, the resistance, particularly the research progress and activity of EGFR degraders via the proteasome and lysosome. Furthermore, this review aims to provide insights for the development of the novel EGFR degraders.

Structural and Physicochemical Features of Oral PROTACs

Achieving oral bioavailability with Proteolysis Targeting Chimeras (PROTACs) is a key challenge. Here, we report the in vivo pharmacokinetic properties in mouse, rat, and dog of four clinical oral PROTACs and compare with an internally derived data set. We use NMR to determine 3D molecular conformations and structural preorganization free in solution, and we introduce the new experimental descriptors, solvent-exposed H-bond donors (eHBD), and acceptors (eHBA). We derive an upper limit of eHBD ≤ 2 for oral PROTACs in apolar environments and show a greater tolerance for other properties (eHBA, polarity, lipophilicity, and molecular weight) than for Rule-of-5 compliant oral drugs. Within a set of structurally related PROTACs, we show that examples with eHBD > 2 have much lower oral bioavailability than those that have eHBD ≤ 2. We summarize our findings as an experimental "Rule-of-oral-PROTACs" in order to assist medicinal chemists to achieve oral bioavailability in this challenging space.

PROTACs in Ovarian Cancer: Current Advancements and Future Perspectives

Ovarian cancer is the deadliest gynecologic malignancy. The majority of patients diagnosed with advanced ovarian cancer will relapse, at which point additional therapies can be administered but, for the most part, these are not curative. As such, a need exists for the development of novel therapeutic options for ovarian cancer patients. Research in the field of targeted protein degradation (TPD) through the use of proteolysis-targeting chimeras (PROTACs) has significantly increased in recent years. The ability of PROTACs to target proteins of interest (POI) for degradation, overcoming limitations such as the incomplete inhibition of POI function and the development of resistance seen with other inhibitors, is of particular interest in cancer research, including ovarian cancer research. This review provides a synopsis of PROTACs tested in ovarian cancer models and highlights PROTACs characterized in other types of cancers with potential high utility in ovarian cancer. Finally, we discuss methods that will help to enable the selective delivery of PROTACs to ovarian cancer and improve the pharmacodynamic properties of these agents.

Orally Bioavailable Proteolysis-Targeting Chimeras: An Innovative Approach in the Golden Era of Discovering Small-Molecule Cancer Drugs

Proteolysis-targeting chimeras (PROTACs) are an emerging therapeutic modality that show promise to open a target space not accessible to conventional small molecules via a degradation-based mechanism. PROTAC degraders, due to their bifunctional nature, which is categorized as 'beyond the Rule of Five', have gained attention as a distinctive therapeutic approach for oral administration in clinical settings. However, the development of PROTACs with adequate oral bioavailability remains a significant hurdle, largely due to their large size and less than ideal physical and chemical properties. This review encapsulates the latest advancements in orally delivered PROTACs that have entered clinical evaluation as well as developments highlighted in recent scholarly articles. The insights and methodologies elaborated upon in this review could be instrumental in supporting the discovery and refinement of novel PROTAC degraders aimed at the treatment of various human cancers.

Beyond Rule of Five and PROTACs in Modern Drug Discovery: Polarity Reducers, Chameleonicity, and the Evolving Physicochemical Landscape

Developing orally bioavailable drugs demands an understanding of absorption in early drug development. Traditional methods and physicochemical properties optimize absorption for rule of five (Ro5) compounds; beyond rule of five (bRo5) drugs necessitate advanced tools like the experimental measure of exposed polarity (EPSA) and the AbbVie multiparametric score (AB-MPS). Analyzing AB-MPS and EPSA against ∼1000 compounds with human absorption data and ∼10,000 AbbVie tool compounds (∼1000 proteolysis targeting chimeras or PROTACs, ∼7000 Ro5s, and ∼2000 bRo5s) revealed new patterns of physicochemical trends. We introduced a high-throughput "polarity reduction" descriptor: ETR, the EPSA-to-topological polar surface area (TPSA) ratio, highlights unique bRo5 and PROTAC subsets for specialized drug design strategies for effective absorption. Our methods and guidelines refine drug design by providing innovative in vitro approaches, enhancing physicochemical property optimization, and enabling accurate predictions of intestinal absorption in the complex bRo5 domain.

Annual review of PROTAC degraders as anticancer agents in 2022

Following nearly two decades of development, significant advancements have been achieved in PROTAC technology. As of the end of 2022, more than 20 drugs have entered clinical trials, with ARV-471 targeting estrogen receptor (ER) showing remarkable progress by entering phase III clinical studies. In 2022, significant progress has been made on multiple targets. The first reversible covalent degrader designed to target the KRASG12C mutant protein, based on cyclopropionamide, has been reported. Additionally, the activity HDCA1 degrader surpassed submicromolar levels during the same year. A novel FEM1B covalent ligand called EN106 was also discovered, expanding the range of available ligands. Furthermore, the first PROTAC drug targeting SOS1 was reported. Additionally, the first-in-class degraders that specifically target BRD4 isoforms (BRD4 L and BRD4 S) have recently been reported, providing a valuable tool for further investigating the biological functions of these isoforms. Lastly, a breakthrough was also achieved with the first degrader targeting both CDK9 and Cyclin T1. In this review, we aimed to update the PROTAC degraders as potential anticancer agents covering articles published in 2022. The design strategies, degradation effects, and anticancer activities were highlighted, which might provide an updated sight to develop novel PROTAC degraders with great potential as anticancer agents as well as favorable drug-like properties.

E3 ubiquitin ligases in lung cancer: Emerging insights and therapeutic opportunities

Aim In this review, we have attempted to provide the readers with an updated account of the role of a family of proteins known as E3 ligases in different aspects of lung cancer progression, along with insights into the deregulation of expression of these proteins during lung cancer. A detailed account of the therapeutic strategies involving E3 ligases that have been developed or currently under development has also been provided in this review. MATERIALS AND METHODS: The review article employs extensive literature search, along with differential gene expression analysis of lung cancer associated E3 ligases using the DESeq2 package in R, and the Gene Expression Profiling Interactive Analysis (GEPIA) database (http://gepia.cancer-pku.cn/). Protein expression analysis of CPTAC lung cancer samples was carried out using the UALCAN webtool (https://ualcan.path.uab.edu/index.html). Assessment of patient overall survival (OS) in response to high and low expression of selected E3 ligases was performed using the online Kaplan-Meier plotter (https://kmplot.com/analysis/index.php?p=background). KEY FINDINGS: SIGNIFICANCE: The review provides an in-depth understanding of the role of E3 ligases in lung cancer progression and an up-to-date account of the different therapeutic strategies targeting oncogenic E3 ligases for improved lung cancer management.

Recent progress in degradation of membrane proteins by PROTACs and alternative targeted protein degradation techniques

Targeted protein degradation (TPD) is one of the key strategies of current targeted cancer therapy, and it can eliminate some of the root causes of cancer, and effectively avoid drug resistance caused by traditional drugs. Proteolysis targeting chimera (PROTAC) is a hot branch of the TPD strategy, and it has been shown to induce the degradation of target proteins by activating the inherent ubiquitin-proteasome system (UPS) in tumor cells. PROTACs have been developed for more than two decades, and some of them have been clinically evaluated. Although most of the proteins degraded by PROTACs are intracellular, degradation of some typical membrane proteins has also been reported, such as epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), programmed death ligand 1 (PD-L1), and G-protein-coupled receptor (GPCR). In addition, some other effective membrane protein-degrading strategies have also emerged, such as antibody-based PROTAC (AbTAC), lysosome targeting chimera (LYTAC), molecular glue, and nanoparticle-based PROTAC (Nano-PROTAC). Herein, we discussed the advantages, disadvantages and potential applications of several important membrane protein degradation techniques. These techniques that we have summarized are insightful in paving the way for future development of more general strategies for membrane protein degradation.

Current advances and development strategies of orally bioavailable PROTACs

Proteolysis-targeting chimeras (PROTACs) have been an area of intensive research with the potential to extend drug space not target to traditional molecules. In the last half decade, we have witnessed several PROTACs initiated phase I/II/III clinical trials, which inspired us a lot. However, the structure of PROTACs beyond "rule of 5" resulted in developing PROTACs with acceptable oral pharmacokinetic (PK) properties remain one of the biggest bottleneck tasks. Many reports have demonstrated that it is possible to access orally bioavailable PROTACs through rational ligand and linker modifications. In this review, we systematically reviewed and highlighted the most recent advances in orally bioavailable PROTACs development, especially focused on the medicinal chemistry campaign of discovery process and in vivo oral PK properties. Moreover, the constructive strategies for developing oral PROTACs were proposed comprehensively. Collectively, we believe that the strategies summarized here may provide references for further development of oral PROTACs.

20 years since the approval of first EGFR-TKI, gefitinib: Insight and foresight

Epidermal growth factor receptor (EGFR) actively involves in modulation of various cancer progression related mechanisms including angiogenesis, differentiation and migration. Therefore, targeting EGFR has surfaced as a prominent approach for the treatment of several types of cancers, including non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma. Various first, second and third generation of EGFR tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated effectiveness as an anti-cancer therapeutics. However, rapid development of drug resistance and mutations still remains a major challenge for the EGFR-TKIs therapy. Overcoming from intrinsic and acquired resistance caused by EGFR mutations warrants the further exploration of alternative strategies and discovery of novel inhibitors. In this review, we delve into the breakthrough discoveries have been made in previous 20 years, and discuss the currently ongoing efforts aimed to circumvent the chemo-resistance. We also highlight the new challenges, limitations and future directions for the development of improved therapeutic approaches such as fourth-generation EGFR-TKIs, peptides, nanobodies, PROTACs etc.

Resistance of Lung Cancer to EGFR-Specific Kinase Inhibitors: Activation of Bypass Pathways and Endogenous Mutators

Epidermal growth factor receptor (EGFR)-specific tyrosine kinase inhibitors (TKIs) have changed the landscape of lung cancer therapy. For patients who are treated with the new TKIs, the current median survival exceeds 3 years, substantially better than the average 20 month survival rate only a decade ago. Unfortunately, despite initial efficacy, nearly all treated patients evolve drug resistance due to the emergence of either new mutations or rewired signaling pathways that engage other receptor tyrosine kinases (RTKs), such as MET, HER3 and AXL. Apparently, the emergence of mutations is preceded by a phase of epigenetic alterations that finely regulate the cell cycle, bias a mesenchymal phenotype and activate antioxidants. Concomitantly, cells that evade TKI-induced apoptosis (i.e., drug-tolerant persister cells) activate an intrinsic mutagenic program reminiscent of the SOS system deployed when bacteria are exposed to antibiotics. This mammalian system imbalances the purine-to-pyrimidine ratio, inhibits DNA repair and boosts expression of mutation-prone DNA polymerases. Thus, the net outcome of the SOS response is a greater probability to evolve new mutations. Deeper understanding of the persister-to-resister transformation, along with the development of next-generation TKIs, EGFR-specific proteolysis targeting chimeras (PROTACs), as well as bispecific antibodies, will permit delaying the onset of relapses and prolonging survival of patients with EGFR+ lung cancer.

Expanding PROTACtable genome universe of E3 ligases

Proteolysis-targeting chimera (PROTAC) and other targeted protein degradation (TPD) molecules that induce degradation by the ubiquitin-proteasome system (UPS) offer new opportunities to engage targets that remain challenging to be inhibited by conventional small molecules. One fundamental element in the degradation process is the E3 ligase. However, less than 2% amongst hundreds of E3 ligases in the human genome have been engaged in current studies in the TPD field, calling for the recruiting of additional ones to further enhance the therapeutic potential of TPD. To accelerate the development of PROTACs utilizing under-explored E3 ligases, we systematically characterize E3 ligases from seven different aspects, including chemical ligandability, expression patterns, protein-protein interactions (PPI), structure availability, functional essentiality, cellular location, and PPI interface by analyzing 30 large-scale data sets. Our analysis uncovers several E3 ligases as promising extant PROTACs. In total, combining confidence score, ligandability, expression pattern, and PPI, we identified 76 E3 ligases as PROTAC-interacting candidates. We develop a user-friendly and flexible web portal ( https://hanlaboratory.com/E3Atlas/ ) aimed at assisting researchers to rapidly identify E3 ligases with promising TPD activities against specifically desired targets, facilitating the development of these therapies in cancer and beyond.

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.

Advances in protein kinase drug discovery through targeting gatekeeper mutations

INTRODUCTION

Acquired resistance caused by gatekeeper mutations has become a major challenge for approved kinase inhibitors used in the clinic. Consequently, the development of new-generation inhibitors or degraders to overcome clinical resistance has become an important research focus for the field.

AREAS COVERED

This review summarizes the common gatekeeper mutations in druggable kinases and the constantly evolving inhibitors or degraders designed to overcome single or double mutations of gatekeeper residues. Furthermore, the authors provide their perspectives on the medicinal chemistry strategies for addressing clinical resistance with gatekeeper mutations.

EXPERT OPINION

The authors suggest optimizing kinase inhibitors to interact effectively with gatekeeper residues, altering the binding mode or binding pocket to avoid steric clashes, improving binding affinity with the target, utilizing protein degraders, and developing combination therapy. These approaches have the potential to be effective in overcoming resistance due to gatekeeper residues.

Proteolysis targeting chimeras in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) has very poor prognosis in advanced stages. Discovery and application of therapies targeting specific oncogenic driver mutations has greatly improved overall survival. However, targeted therapies are limited in their efficacy due to resistance mutations that may arise with long term use. Proteolysis targeting Chimeras (PROTACs) are a promising approach to combating resistance mutations. PROTACs commandeer innate ubiquitination machinery to degrade oncogenic proteins. Here we review the PROTACs that have been developed for targeting common EGFR, KRAS, and ALK mutations.

Structure-Activity Relationship Studies Based on Quinazoline Derivatives as EGFR Kinase Inhibitors (2017-Present)

The epidermal growth factor receptor (EGFR) plays a critical role in the tumorigenesis of various forms of cancer. Targeting the mutant forms of EGFR has been identified as an attractive therapeutic approach and led to the approval of three generations of inhibitors. The quinazoline core has emerged as a favorable scaffold for the development of novel EGFR inhibitors due to increased affinity for the active site of EGFR kinase. Currently, there are five first-generation (gefitinib, erlotinib, lapatinib, vandetanib, and icotinib) and two second-generation (afatinib and dacomitinib) quinazoline-based EGFR inhibitors approved for the treatment of various types of cancers. The aim of this review is to outline the structural modulations favorable for the inhibitory activity toward both common mutant (del19 and L858R) and resistance-conferring mutant (T790M and C797S) EGFR forms, and provide an overview of the newly synthesized quinazoline derivatives as potentially competitive, covalent or allosteric inhibitors of EGFR.

Targeted therapy based on ubiquitin-specific proteases, signalling pathways and E3 ligases in non-small-cell lung cancer

Lung cancer is one of the most common malignant tumours worldwide, with the highest mortality rate. Approximately 1.6 million deaths owing to lung cancer are reported annually; of which, 85% of deaths occur owing to non-small-cell lung cancer (NSCLC). At present, the conventional treatment methods for NSCLC include radiotherapy, chemotherapy, targeted therapy and surgery. However, drug resistance and tumour invasion or metastasis often lead to treatment failure. The ubiquitin–proteasome pathway (UPP) plays an important role in the occurrence and development of tumours. Upregulation or inhibition of proteins or enzymes involved in UPP can promote or inhibit the occurrence and development of tumours, respectively. As regulators of UPP, ubiquitin-specific proteases (USPs) primarily inhibit the degradation of target proteins by proteasomes through deubiquitination and hence play a carcinogenic or anticancer role. This review focuses on the role of USPs in the occurrence and development of NSCLC and the potential of corresponding targeted drugs, PROTACs and small-molecule inhibitors in the treatment of NSCLC.

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

Epidermal growth factor receptor (EGFR) is an oncogenic drug target and plays a critical role in several cellular functions including cancer cell growth, survival, proliferation, differentiation, and motility. Several small-molecule tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAbs) have been approved for targeting intracellular and extracellular domains of EGFR, respectively. However, cancer heterogeneity, mutations in the catalytic domain of EGFR, and persistent drug resistance limited their use. Different novel modalities are gaining a position in the limelight of anti-EGFR therapeutics to overcome such limitations. The current perspective reflects upon newer modalities, importantly the molecular degraders such as PROTACs, LYTACs, AUTECs, and ATTECs, etc., beginning with a snapshot of traditional and existing anti-EGFR therapies including small molecule inhibitors, mAbs, and antibody drug conjugates (ADCs). Further, a special emphasis has been made on the design, synthesis, successful applications, state-of-the-art, and emerging future opportunities of each discussed modality.

PROTAC therapy as a new targeted therapy for lung cancer

Despite recent advances in molecular therapeutics, lung cancer is still a leading cause of cancer deaths. Currently, limited targeted therapy options and acquired drug resistance present significant barriers in the treatment of patients with lung cancer. New strategies in drug development, including those that take advantage of the intracellular ubiquitin-proteasome system to induce targeted protein degradation, have the potential to advance the field of personalized medicine for patients with lung cancer. Specifically, small molecule proteolysis targeting chimeras (PROTACs), consisting of two ligands connected by a linker that bind to a target protein and an E3 ubiquitin ligase, have been developed against many cancer targets, providing promising opportunities for advanced lung cancer. In this review, we focus on the rationale for PROTAC therapy as a new targeted therapy and the current status of PROTAC development in lung cancer.

Advancing Strategies for Proteolysis-Targeting Chimera Design

Proteolysis-targeting chimeras (PROTACs) have shown great therapeutic potential by degrading various disease-causing proteins, particularly those related to tumors. Therefore, the introduction of PROTACs has ushered in a new chapter of antitumor drug development, marked by significant advances over recent years. Herein, we describe recent developments in PROTAC technology, focusing on design strategy, development workflow, and future outlooks. We also discuss potential opportunities and challenges for PROTAC research.

Mechanisms of Acquired Resistance and Tolerance to EGFR Targeted Therapy in Non-Small Cell Lung Cancer

Non-small cell lung cancers (NSCLC) harboring activating mutations of the epidermal growth factor receptor (EGFR) are treated with specific tyrosine kinase inhibitors (EGFR-TKIs) of this receptor, resulting in clinically responses that can generally last several months. Unfortunately, EGFR-targeted therapy also favors the emergence of drug tolerant or resistant cells, ultimately resulting in tumor relapse. Recently, cellular barcoding strategies have arisen as a powerful tool to investigate the clonal evolution of these subpopulations in response to anti-cancer drugs. In this review, we provide an overview of the currently available treatment options for NSCLC, focusing on EGFR targeted therapy, and discuss the common mechanisms of resistance to EGFR-TKIs. We also review the characteristics of drug-tolerant persister (DTP) cells and the mechanistic basis of drug tolerance in EGFR-mutant NSCLC. Lastly, we address how cellular barcoding can be applied to investigate the response and the behavior of DTP cells upon EGFR-TKI treatment.