Olmutinib: First Global Approval

Design, synthesis and bioevaluation of dual EGFR-PI3Kα inhibitors for potential treatment of NSCLC

Aberrant activation or mutation of the EGFR-PI3K-Akt-mTOR signaling pathway has been implicated in a wide range of human cancers, especially non-small-cell lung cancer (NSCLC). Thus, dual inhibition of EGFR and PI3K has been investigated as a promising strategy to address acquired drug resistance resulting from the use of tyrosine kinase inhibitors. A series of dual EGFR/PI3Kα inhibitors was synthesized using pharmacophore hybridization of the third-generation EGFR inhibitor olmutinib and the PI3Kα selective inhibitor TAK-117. The optimal compound 30k showed potent kinase inhibitory activities with IC50 values of 3.6 and 30.0 nM against EGFRL858R/T790M and PI3Kα, respectively. Compound 30k exhibited a significant antiproliferative effect in NCI-H1975 cells with a higher selectivity profile than olmutinib. The potential antitumor mechanism, molecular binding modes, and in vitro metabolic stability of compound 30k were also clarified.

Design, synthesis, and evaluation of antitumor activity of Mobocertinib derivatives, a third-generation EGFR inhibitor

Mobocertinib, as a structural analog of the third generation TKI Osimertinib, can selectively act on the EGFRex20 mutation. We have structurally modified Mobocertinib to obtain new EGFR inhibitors. In this paper, we chose Mobocertinib as a lead compound for structural modification to investigate the effect of Mobocertinib derivatives on EGFRT790M mutation. We designed and synthesized 63 Mobocertinib derivatives by structural modification using the structural similarity strategy and the bioelectronic isoarrangement principle. Then, we evaluated the in vitro antitumor activity of the 63 Mobocertinib derivatives and found that the IC50 of compound H-13 against EGFRL858R/T790M mutated H1975 cells was 3.91 μM, and in further kinase activity evaluation, the IC50 of H-13 against EGFRL858R/T790M kinase was 395.2 nM. In addition, the preferred compound H-13 was able to promote apoptosis of H1975 tumor cells and block the proliferation of H1975 cells in the G0/G1 phase; meanwhile, it was able to significantly inhibit the migratory ability of H1975 tumor cells and inhibit the growth of H1975 cells in a time-concentration-dependent manner. In the in vivo anti-tumor activity study, the preferred compound H-13 had no obvious toxicity to normal mice, and the tumor inhibition effect on H1975 cell-loaded nude mice was close to that of Mobocertinib. Finally, molecular dynamics simulations showed that the binding energy between compound H-13 and 3IKA protein was calculated to be -162.417 ± 14.559 kJ/mol. In summary, the preferred compound H-13 can be a potential third-generation EGFR inhibitor.

Fused thiophene as a privileged scaffold: A review on anti-Alzheimer's disease potentials via targeting cholinesterases, monoamine oxidases, glycogen synthase kinase-3, and Aβ aggregation

As a "silent threat," Alzheimer's disease (AD) is quickly rising to the top of the list of costly and troublesome diseases facing humanity. It is growing to be one of the most troublesome and expensive conditions, with annual health care costs higher than those of cancer and comparable to those of cardiovascular disorders. One of the main pathogenic characteristics of AD is the deficiency of the neurotransmitter acetylcholine (ACh) which plays a vital role in memory, learning, and attention. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) play a crucial role in hydrolyzing ACh. Consequently, a frequent therapy approach for AD is the suppression of AChE and BChE to improve cholinergic neurotransmission and reduce cognitive symptoms. The accumulation of amyloid plaques (Aβ) is a primary factor contributing to neurodegenerative diseases, particularly AD. Glycogen synthase kinase-3β (GSK3-β) is regarded as a pivotal player in the pathophysiology of AD since dysregulation of this kinase affects all major hallmarks of the disease, such as tau phosphorylation, Aβ aggregation, memory, neurogenesis, and synaptic function. One of the most challenging and risky issues in modern medicinal chemistry is the urgent and ongoing need for the study and development of effective therapeutic candidates for the treatment of AD. A significant class of heterocyclic molecules that can target the complex and multifactorial pathogenesis of AD are fused thiophene derivatives. The goal of the current review is to demonstrate the advancements made in fused thiophene derivatives' anti-AD activity. It also covers their mechanisms of action and studies of the structure-activity relationships in addition to the compilation of significant synthetic routes for fused thiophene derivatives with anti-AD potential. This review is intended to stimulate new ideas in the search for more rationale designs of derivatives based on fused thiophene, hoping to be more potent in treating AD.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

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.

Computer aided drug discovery (CADD) of a thieno[2,3-d]pyrimidine derivative as a new EGFR inhibitor targeting the ribose pocket

Depending on the pharmacophoric characteristics of EGFR inhibitors, a new thieno[2,3-d]pyrimidine derivative has been developed. Firstly, the potential inhibitory effect of the designed compound against EGFR has been proven by docking experiments that showed correct binding modes and excellent binding energies of -98.44 and -88.00 kcal/mol, against EGFR wild-type and mutant type, respectively. Furthermore, MD simulations studies confirmed the precise energetic, conformational, and dynamic alterations that occurred after binding to EGFR. The correct binding was also confirmed by essential dynamics studies. To further investigate the general drug-like properties of the developed candidate, in silico ADME and toxicity studies have also been carried out. The thieno[2,3-d]pyrimidine derivative was synthesized following the earlier promising findings. Fascinatingly, the synthesized compound (4) showed promising inhibitory effects against EGFRWT and EGFRT790M with IC50 values of 25.8 and 182.3 nM, respectively. Also, it exhibited anticancer potentialities against A549 and MCF-7cell lines with IC50 values of 13.06 and 20.13 µM, respectively. Interestingly, these strong activities were combined with selectivity indices of 2.8 and 1.8 against the two cancer cell lines, respectively. Further investigations indicated the ability of compound 4 to arrest the cancer cells' growth at the G2/M phase and to increase early and late apoptosis percentages from 2.52% and 2.80 to 17.99% and 16.72%, respectively. Additionally, it was observed that compound 4 markedly increased the levels of caspase-3 and caspase-9 by 4 and 3-fold compared to the control cells. Moreover, it up-regulated the level of BAX by 3-fold and down-regulated the level of Bcl-2 by 3-fold affording a BAX/Bcl-2 ratio of 9.Communicated by Ramaswamy H. Sarma.

Advances of clinically approved small-molecule drugs for the treatment of non-small cell lung cancer

Lung cancer continues to pose a significant challenge as a prominent contributor to global cancer-related mortality. Despite the considerable strides made in therapeutic interventions within the past decade, a substantial population of patients diagnosed with non-small cell lung cancer (NSCLC) still face the grim reality of an incurable condition. In the realm of optimal management strategies for individuals afflicted with locally advanced, yet amenable to surgical resection, NSCLC, a therapeutic approach encompassing chemoradiation stands as a fundamental component. Significant strides have been made in the therapeutic landscape of NSCLC during the preceding two decades, facilitating an enhanced comprehension of the underlying disease biology, and mechanisms governing tumor progression, as well as advancements in early detection modalities and multimodal therapeutic interventions. Nevertheless, the overall rates of curative interventions and survival outcomes for NSCLC continue to exhibit a discouragingly low trajectory, particularly in the context of metastatic disease. Hence, the imperative for sustained research endeavors in the realm of novel pharmaceutical agents and combinatorial therapeutic approaches remains paramount, with the overarching objective of broadening the scope of clinical advantages conferred upon a wider demographic of patients, thereby fostering tangible improvements in outcomes pertaining to NSCLC. The primary objective of this review is to provide an all-encompassing examination encompassing the clinical application and synthetic routes of specific drugs, with the explicit aim of disseminating invaluable knowledge that can inform future research and development endeavors focused on NSCLC.

The impacts of CYP3A4 genetic polymorphism and drug interactions on the metabolism of lurasidone

The aim of this study was to investigate the impacts of 24 variants of recombinant human CYP3A4 and drug interactions on the metabolism of lurasidone. In vitro, enzymatic reaction incubation system of CYP3A4 was established to determine the kinetic parameters of lurasidone catalyzed by 24 CYP3A4 variants. Then, we constructed rat liver microsomes (RLM) and human liver microsomes (HLM) incubation system to screen potential anti-tumor drugs that could interact with lurasidone and studied its inhibitory mechanism. In vivo, Sprague-Dawley (SD) rats were applied to study the interaction between lurasidone and olmutinib. The concentrations of the analytes were detected by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). As the results, we found that compared with the wild-type CYP3A4, the relative intrinsic clearances vary from 355.77 % in CYP3A4.15 to 14.11 % in CYP3A4.12. A series of drugs were screened based on the incubation system, and compared to without olmutinib, the amount of ID-14283 (the metabolite of lurasidone) in RLM and HLM were reduced to 7.22 % and 7.59 %, and its IC50 were 18.83 ± 1.06 μM and 16.15 ± 0.81 μM, respectively. At the same time, it exerted inhibitory effects both through a mixed mechanism. When co-administration of lurasidone with olmutinib in rats, the AUC(0-t) and AUC(0-∞) of lurasidone were significantly increased by 73.52 % and 69.68 %, respectively, while CLz/F was observably decreased by 43.83 %. In conclusion, CYP3A4 genetic polymorphism and olmutinib can remarkably affect the metabolism of lurasidone.

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.

Recent advances in targeting the "undruggable" proteins: from drug discovery to clinical trials

Undruggable proteins are a class of proteins that are often characterized by large, complex structures or functions that are difficult to interfere with using conventional drug design strategies. Targeting such undruggable targets has been considered also a great opportunity for treatment of human diseases and has attracted substantial efforts in the field of medicine. Therefore, in this review, we focus on the recent development of drug discovery targeting "undruggable" proteins and their application in clinic. To make this review well organized, we discuss the design strategies targeting the undruggable proteins, including covalent regulation, allosteric inhibition, protein-protein/DNA interaction inhibition, targeted proteins regulation, nucleic acid-based approach, immunotherapy and others.

Design, synthesis and molecular docking study of new pyrimidine-based hydrazones with selective anti-proliferative activity against MCF-7 and MDA-MB-231 human breast cancer cell lines

Efforts were directed on the design, synthesis and evaluation of the anticancer activity of some pyrimidine-based hydrazones against two breast cancer cell lines, MCF-7 and MDA-MB-231. Preliminary screening results revealed that some candidates scrutinized for their antiproliferative activities exhibited IC50 values of 0.87 μM-12.91 μM in MCF-7 and 1.75 μM-9.46 μM in MDA-MB-231 cells, indicating almost equal activities on both cell lines and better growth inhibition activities than those of the positive control 5-fluorouracil (5-FU) which displayed IC50 values of 17.02 μM and 11.73 μM respectively. Selectivity of the significantly active compounds was estimated against MCF-10A normal breast cells when compounds 7c, 8b, 9a and 10b exhibited superior activity for cancerous cells than for normal cells when compound 10b presented the best selectivity Index (SI) with respect to both MCF-7 and MDA-MB-231 cancer cells in comparison to the reference drug 5-FU. Mechanisms of their actions were explored by inspecting activation of caspase-9, annexin V staining and cell cycle analysis. It was noticed that compounds 7c, 8b, 8c 9a-c and 10b produced an increase in caspase-9 levels in MCF-7 treated cells with 10b inducing the highest elevation (27.13 ± 0.54 ng/mL) attaining 8.26-fold when compared to control MCF-7 which was higher than that of staurosporine (19.011 ± 0.40 ng/mL). The same compounds boosted caspase-9 levels in MDA-MB-231 treated cells when an increase in caspase-9 concentration reaching 20.40 ± 0.46 ng/mL (4.11-fold increase) was observed for compound 9a. We also investigated the role of these compounds for their increasing apoptosis ability against the 2 cell lines. Compounds 7c, 8b and 10b tested on MCF-7 cells displayed pre-G1 apoptosis and arrested cell cycle in particular at the S and G1 phases. Further clarification of their effects was made by modulating their related activities as inhibitors of ARO and EGFR enzymes when 8c and 9b showed 52.4% and 58.9% inhibition activity relative to letrozole respectively and 9b and 10b showed 36% and 39% inhibition activity of erlotinib. Also, the inhibition activity was verified by docking into the chosen enzymes.

Synthesis and initial in vitro evaluation of olmutinib derivatives as prospective imaging probe for non-small cell lung cancer

Introduction

Imaging a non-small cell lung cancer (NSCLC) using radiolabeled tyrosine kinase inhibitors (TKIs) has attracted attention due to their unique interaction with the target epidermal growth factor receptor (EGFR). Olmutinib (OTB) is one of the third-generation EGFR TKIs, which selectively inhibit EGFR L858R/T790M mutation. In this study, we aim to estimate the interaction of the iodinated OTB (I-OTB)-receptor complex by molecular docking. Furthermore, we will synthesize the I-OTB and evaluate its activity toward EGFR L858R/T790M by in vitro cytotoxicity assay.

Methods

A molecular docking simulation was carried out using an AutoDock Vina program package to estimate the interaction of the ligand-receptor complex. The I-OTB, N-{3-iodo-5-[(2-{[4-(4-methylpiperazin-1-yl)phenyl]aminothieno{3,2-d}pyrimidin-4-yl)oxy]phenyl} acrylamide, was synthesized by introducing an iodine atom in the phenyl group in the 3-aryloxyanilide structure. The half inhibitory concentration (IC50) was determined by employing a 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium monosodium salt (WST-8) assay to evaluate the activity of I-OTB.

Results

The docking study exhibited that I-OTB could take an interaction similar to that of the parent compound. We successfully synthesized I-OTB and confirmed its structure by instrumental analysis. The binding energy of OTB and I-OTB in complex with EGFR T790M are -8.7 and -7.9 kcal/mol, respectively. The cytotoxicity assay showed that I-OTB also has an affinity towards the EGFR L858R/T790M mutation with the IC50 10.49 ± 5.64 𝜇M compared to the EGFR wild type with the IC50 over than 10 𝜇M.

Conclusion

The cytotoxicity effect of I-OTB was comparable to that of OTB. This result indicates that the iodine substituent in OTB did not alter the parent compound selectivity toward double mutations EGFR L858R/T790M. Therefore, I-OTB is prominent for radioiodination, and [123/124I] I-OTB may be a promising candidate for EGFR L858R/T790M mutation imaging.

Small molecule protein kinase inhibitors approved by regulatory agencies outside of the United States

Owing to genetic alterations and overexpression, the dysregulation of protein kinases plays a significant role in the pathogenesis of many autoimmune and neoplastic disorders and protein kinase antagonists have become an important drug target. Although the efficacy of imatinib in the treatment of chronic myelogenous leukemia in the United States in 2001 was the main driver of protein kinase inhibitor drug discovery, this was preceded by the approval of fasudil (a ROCK antagonist) in Japan in 1995 for the treatment of cerebral vasospasm. There are 21 small molecule protein kinase inhibitors that are approved in China, Japan, Europe, and South Korea that are not approved in the United Sates and 75 FDA-approved inhibitors in the United States. Of the 21 agents, eleven target receptor protein-tyrosine kinases, eight inhibit nonreceptor protein-tyrosine kinases, and two block protein-serine/threonine kinases. All 21 drugs are orally bioavailable or topically effective. Of the non-FDA approved drugs, sixteen are prescribed for the treatment of neoplastic diseases, three are directed toward inflammatory disorders, one is used for glaucoma, and fasudil is used in the management of vasospasm. The leading targets of kinase inhibitors approved by both international regulatory agencies and by the FDA are members of the EGFR family, the VEGFR family, and the JAK family. One-third of the 21 internationally approved drugs are not compliant with Lipinski's rule of five for orally bioavailable drugs. The rule of five relies on four parameters including molecular weight, number of hydrogen bond donors and acceptors, and the Log of the partition coefficient.

Discovery of new thieno[2,3-d]pyrimidines as EGFR tyrosine kinase inhibitors for cancer treatment

Background: EGFR has been considered a vital molecular target in cancer management. Aim: The discovery of new thieno[2,3-d]pyrimidine derivatives as EGFR tyrosine kinase inhibitors. Methods: Nine derivatives were designed, synthesized and subjected to in vitro and in silico studies. Results: Compound 7a significantly inhibited the growth of HepG2 and PC3 cells for both EGFR wild-type and EGFRT790M. Compound 7a caused a significant apoptotic effect, arresting HepG2 cells' growth in the S and G2/M phases. Docking and molecular dynamics simulation studies confirmed the correct and stable binding modes of the synthesized compounds against the active sites. Conclusion: Compound 7a is a promising dual EGFR inhibitor for cancer treatment.

Theranostic applications of selenium nanomedicines against lung cancer

The incidence and mortality rates of lung cancer are among the highest in the world. Traditional treatment methods include surgery, chemotherapy, and radiotherapy. Although rapid progress has been achieved in the past decade, treatment limitations remain. It is therefore imperative to identify safer and more effective therapeutic methods, and research is currently being conducted to identify more efficient and less harmful drugs. In recent years, the discovery of antitumor drugs based on the essential trace element selenium (Se) has provided good prospects for lung cancer treatments. In particular, compared to inorganic Se (Inorg-Se) and organic Se (Org-Se), Se nanomedicine (Se nanoparticles; SeNPs) shows much higher bioavailability and antioxidant activity and lower toxicity. SeNPs can also be used as a drug delivery carrier to better regulate protein and DNA biosynthesis and protein kinase C activity, thus playing a role in inhibiting cancer cell proliferation. SeNPs can also effectively activate antigen-presenting cells to stimulate cell immunity, exert regulatory effects on innate and regulatory immunity, and enhance lung cancer immunotherapy. This review summarizes the application of Se-based species and materials in lung cancer diagnosis, including fluorescence, MR, CT, photoacoustic imaging and other diagnostic methods, as well as treatments, including direct killing, radiosensitization, chemotherapeutic sensitization, photothermodynamics, and enhanced immunotherapy. In addition, the application prospects and challenges of Se-based drugs in lung cancer are examined, as well as their forecasted future clinical applications and sustainable development.

Development of Furanopyrimidine-Based Orally Active Third-Generation EGFR Inhibitors for the Treatment of Non-Small Cell Lung Cancer

The development of orally bioavailable, furanopyrimidine-based double-mutant (L858R/T790M) EGFR inhibitors is described. First, selectivity for mutant EGFR was accomplished by replacing the (S)-2-phenylglycinol moiety of 12 with either an ethanol or an alkyl substituent. Then, the cellular potency and physicochemical properties were optimized through insights from molecular modeling studies by implanting various solubilizing groups in phenyl rings A and B. Optimized lead 52 shows 8-fold selective inhibition of H1975 (EGFR^L858R/T790M overexpressing) cancer cells over A431 (EGFR^WT overexpressing) cancer cells; western blot analysis further confirmed EGFR mutant-selective target modulation inside the cancer cells by 52. Notably, 52 displayed in vivo antitumor effects in two different mouse xenograft models (BaF3 transfected with mutant EGFR and H1975 tumors) with TGI = 74.9 and 97.5% after oral administration (F = 27%), respectively. With an extraordinary kinome selectivity (S(10) score of 0.017), 52 undergoes detailed preclinical development.

Small Molecule EGFR Inhibitors as Anti-Cancer Agents: Discovery, Mechanisms of Action, and Opportunities

Epidermal growth factor receptors (EGFRs) are a class of receptor tyrosine kinase that are also called ErbB1 and HER1. EGFR tyrosine kinase activity inhibition is considered a promising therapeutic strategy for the treatment of cancer. Many small-molecule inhibitors of EGFR tyrosine kinase (EGFR-TK), from medicinally privileged molecules to commercial drugs, have been overviewed. Particular attention has been paid to the structure of the molecule and its mechanism of action if reported. Subsequent classification of the molecules under discussion has been carried out. Both natural and synthetic and reversible and irreversible EGFR-tyrosine kinase inhibitors have been discussed. Various types of cancers that are caused by overexpression of the EGFR gene, their possible molecular origins, and their natures have also been counted in this article. Because the EGFR signaling pathway controls the proliferation, growth, survival, and differentiation of cells, and the mutated EGFR gene overproduces EGFR protein, which ultimately causes several types of cancer, proper understanding of the molecular dynamics between the protein structure and its inhibitors will lead to more effective and selective EGFR-TKIs, which in turn will be able to save more lives in the battle against cancer.

To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors

Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.

Identification of the structural features of quinazoline derivatives as EGFR inhibitors using 3D-QSAR modeling, molecular docking, molecular dynamics simulations and free energy calculations

Epidermal growth factor receptor (EGFR) is a promising target for the treatment of different types of malignant tumors. Therefore, a combined molecular modeling study was performed on a series of quinazoline derivatives as EGFR inhibitors. The optimum ligand-based CoMFA and CoMSIA models showed reliable and satisfactory predictability (with R²_cv=0.681, R²_ncv=0.844, R²_pred=0.8702 and R²_cv=0.643, R²_ncv=0.874, R²_pred=0.6423). The derived contour maps provide structural features to improve inhibitory activity. Furthermore, the contour maps, molecular docking, and molecular dynamics (MD) simulations have good consistency, illustrating that the derived models are reliable. In addition, MD simulations and binding free energy calculations were also carried out to understand the conformational fluctuations at the binding pocket of the receptor. The results indicate that hydrogen bond, hydrophobic and electrostatic interactions play significant roles on activity and selectivity. Furthermore, amino acids Val31, Lys50, Thr95, Leu149 and Asp160 are considered as essential residues to participate in the ligand-receptor interactions. Overall, this work would offer reliable theoretical basis for future structural modification, design and synthesis of novel EGFR inhibitors with good potency.Communicated by Ramaswamy H. Sarma.

Targeting Gatekeeper Mutations for Kinase Drug Discovery

Clinically acquired resistance is a major challenge in cancer therapies with small-molecule kinase inhibitors (SMKIs). Gatekeeper mutations in the ATP-binding pocket of kinases are the most common mutations leading to acquired resistance. To date, seven new-generation kinase inhibitors targeting gatekeeper mutations have been approved by the FDA; however, the clinical need is still unmet. Here, we systematically summarize the types of gatekeeper mutations across the kinase family, the structural basis for acquired resistance, and newly developed SMKIs targeting gatekeeper mutations as well as highlight the opportunities and challenges of kinase drug discovery for targeting gatekeeper mutations.

Inhibition of IκB Kinase Is a Potential Therapeutic Strategy to Circumvent Resistance to Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) remains as an intractable malignancy with limited therapeutic targets. High expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis of TNBC; however, EGFR targeting has failed with unfavorable clinical outcomes. Here, we performed a combinatorial screening of fifty-five protein kinase inhibitors with the EGFR inhibitor gefitinib in the TNBC cell line MDA-MB-231 and identified the IκB kinase (IKK) inhibitor IKK16 as a sensitizer of gefitinib. Cell viability and clonogenic survival assays were performed to evaluate the antiproliferative effects of the gefitinib and IKK16 (Gefitinib + IKK16) combination in TNBC cell lines. Western blot analyses were also performed to reveal the potential mode of action of this combination. In addition, next-generation sequencing (NGS) analysis was performed in Gefitinib+IKK16-treated cells. The Gefitinib+IKK16 treatment synergistically reduced cell viability and colony formation of TNBC cell lines such as HS578T, MDA-MB-231, and MDA-MB-468. This combination downregulated p-STAT3, p-AKT, p-mTOR, p-GSK3β, and p-RPS6. In addition, p-NF-κB and the total NF-κB were also regulated by this combination. Furthermore, NGS analysis revealed that NF-κB/RELA targets including CCL2, CXCL8, EDN1, IL-1β, IL-6, and SERPINE1 were further reduced and several potential tumor suppressors, such as FABP3, FADS2, FDFT1, SEMA6A, and PCK2, were synergistically induced by the Gefitinib-+IKK16 treatment. Taken together, we identified the IKK/NF-κB pathway as a potential target in combination of EGFR inhibition for treating TNBC.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Design, synthesis and biological evaluation of novel tumor hypoxia-activated EGFR tyrosine kinase inhibitors

Hypoxia is widespread in solid tumors, such as NSCLC, and has become a very attractive target. On the basis of AZD9291 scaffold, novel hypoxia-targeted EGFR inhibitors without the acrylamide warhead but containing hypoxic reductive activation groups were described. Among them, compound JT21 exhibited impressive inhibitory activity (IC₅₀ = 23 nM) against EGFR^L858R/T790M and displayed about 21-fold inhibitory activity decrease against EGFR^wt. Under hypoxia, JT21 exhibited more significant proliferation inhibitory activities against H1975 cells (IC₅₀ = 7.39 ± 2.20 nM) and HCC827 cells (IC₅₀ = 5.88 ± 0.85 nM) than that of AZD9291, which was about 5 times more effective than normoxia activities. Meanwhile, the weak inhibition effects on A549 and BEAS-2B cells suggested JT21 might be a selective inhibitor for EGFR mutations with low toxicity. Furthermore, JT21 could induce apoptosis of H1975 cells under hypoxia and showed good bio-reductive property.

Novel anilinopyrimidine derivatives as potential EGFRT790M/C797S Inhibitors: Design, Synthesis, biological activity study

EGFR^T790M/C797S is an important target for the development of new generation of EGFR kinase inhibitors without drug resistance. In this work, a series of anilinopyrimidine derivatives that targeting EGFR^T790M/C797S were designed, synthesized, and evaluated in vitro for the inhibitory effect on triple mutations kinases and cell lines. Based on the pharmacology data, the anilinopyrimidine derivatives showed high inhibitory activity on triple mutations kinases (EGFR^{del 18/T790M/C797S} and EGFR^{L858R/T790M/C797S}) as well as the cell line Ba/F3 with highly expression of EGFR^{del 18/T790M/C797S}. In addition, the anilinopyrimidine derivatives had a more than 50-fold selectivity towards EGFR^{del 18/T790M/C797S} as compared with EGFR^WT. In vivo antitumor activity test also indicated that 8j had good pharmacokinetic parameters, low toxicity and better inhibitory activity. Overall, the anilinopyrimidine derivatives could be regarded as promising candidates for the further development of novel EGFR^T790M/C797S inhibitors for clinical application.

New Benzimidazole-, 1,2,4-Triazole-, and 1,3,5-Triazine-Based Derivatives as Potential EGFRWT and EGFRT790M Inhibitors: Microwave-Assisted Synthesis, Anticancer Evaluation, and Molecular Docking Study

A new series of benzimidazole, 1,2,4-triazole, and 1,3,5-triazine derivatives were designed and synthesized using a microwave irradiation synthetic approach utilizing 2-phenylacetyl isothiocyanate (1) as a key starting material. All the new analogues were evaluated as anticancer agents against a panel of cancer cell lines utilizing doxorubicin as a standard drug. Most of the tested derivatives exhibited selective cytotoxic activity against MCF-7 and A-549 cancer cell lines. Furthermore, the new target compounds 5, 6, and 7 as the most potent antiproliferative agents have been assessed as in vitro EGFRWT and EGFRT790M inhibitors compared to the reference drugs erlotinib and AZD9291. They represented more potent suppression activity against the mutated EGFRT790M than the wild-type EGFRWT. Moreover, the compounds 5, 6, and 7 down-regulated the oncogenic parameter p53 ubiquitination. A docking simulation of compound 6b was carried out to correlate its molecular structure with its significant EGFR inhibition potency and its possible binding interactions within the active site of EGFRWT and the mutant EGFRT790M.

Metabolic disposition of the EGFR covalent inhibitor furmonertinib in humans

Furmonertinib was designed for the treatment of non-small cell lung cancer (NSCLC) patients with EGFR T790M mutation. In this study, we investigated the metabolic disposition and mass balance in humans and tissue distribution in rats. After a single oral administration of 97.9 μCi/81.5 mg [14C]-furmonertinib mesylate to six healthy male volunteers, the absorption process of furmonertinib was fast with a tmax of total plasma radioactivity at 0.75 h. Afterward, furmonertinib was extensively metabolized, with the parent drug and active metabolite AST5902 accounting for 1.68% and 0.97% of total radioactivity in plasma. The terminal t1/2 of total radioactivity in plasma was as long as 333 h, suggesting that the covalent binding of drug-related substances to plasma proteins was irreversible to a great extent. The most abundant metabolites identified in feces were desmethyl metabolite (AST5902), cysteine conjugate (M19), and parent drug (M0), which accounted for 6.28%, 5.52%, and 1.38% of the dose, respectively. After intragastric administration of 124 μCi/9.93 mg/kg [14C]-furmonertinib to rats, drug-related substances were widely and rapidly distributed in tissues within 4 h. The concentration of total radioactivity in the lung was 100-fold higher than that in rat plasma, which could be beneficial to the treatment of lung cancer. Mass balance in humans was achieved with 77.8% of the administered dose recovered in excretions within 35 days after administration, including 6.63% and 71.2% in urine and feces, respectively. In conclusion, [14C]-furmonertinib is completely absorbed and rapidly distributed into lung tissue, extensively metabolized in humans, presented mostly as covalent conjugates in plasma, and slowly eliminated mostly via fecal route.

Discovery of Cysteine-targeting Covalent Protein Kinase Inhibitors

Small molecule covalent kinase inhibitors (CKIs) have entered a new era in drug discovery, which have the advantage for sustained target inhibition and high selectivity. An increased understanding of binding kinetics of CKIs and discovery of additional irreversible and reversible-covalent cysteine-targeted warheads has inspired the development of this area. Herein, we summarize the major medicinal chemistry strategies employed in the discovery of these representative CKIs, which are categorized by the location of the target cysteine within seven main regions of the kinase: the front region, the glycine rich loop (P-loop), the hinge region, the DFG region, the activation loop (A-loop), the catalytic loop (C-loop), and the remote loop. The emphasis is placed on the design and optimization strategies of CKIs that are generated by addition of a warhead to a reversible lead/inhibitor scaffold. In addition, we address the challenges facing this area of drug discovery.

Design, synthesis and biological evaluation of aminopyrimidine derivatives bearing a 4,5,6,7-tetrahydrothieno [3,2-c]pyridine as potent EGFR inhibitors

To resolve the problem of drug resistance caused by epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer, we used the principle of collocation to design and synthesize a series of aminopyrimidine derivatives with 4,5,6,7-tetrahydrothieno [3,2-c]pyridine side chains (according to the binding mode of AZD9291 to EGFR^T790M) for use as EGFR^L858R/T790M kinase inhibitors. The most promising compound A12, a non-covalently bound reversible inhibitor, showed excellent kinase inhibitory activity against EGFR^L858R/T790M, with an IC₅₀ value of 4.0 nM and more than 42-fold selectivity for EGFR^WT (IC₅₀ = 170.0 nM). Moreover, compound A12 showed strong anti-proliferative activity against H1975 cells, with IC₅₀ value of 0.086 μΜ. Additionally, the effective inhibition of cell migration and the promotion of apoptosis by A12 verified its mechanism of action, as a selective inhibitor of EGFR^L858R/T790M.

Challenge and countermeasures for EGFR targeted therapy in non-small cell lung cancer

Lung cancer causes the highest mortality compared to other cancers in the world according to the latest WHO reports. Non-small cell lung cancer (NSCLC) contributes about 85% of total lung cancer cases. An extensive number of risk factors are attributed to the progression of lung cancer. Epidermal growth factor receptor (EGFR), one of the most frequently mutant driver genes, is closely involved in the development of lung cancer through regulation of the PI3K/AKT and MAPK pathways. As a representative of precision medicine, EGFR-tyrosine kinase inhibitors (TKIs) targeted therapy significantly relieves the development of activating mutant EGFR-driven NSCLC. However, treatment with TKIs facilitates the emergence of acquired resistance that continues to pose a significant hurdle with respect to EGFR targeted therapy. In this review, the development of current approved EGFR-TKIs as well as the related supporting clinical trials are summarized and discussed. Mechanisms of action and resistance were addressed respectively, which serve as important guides to understanding acquired resistance. We also explored the corresponding combination treatment options according to different resistance mechanisms. Future challenges include more comprehensive characterization of unclear resistance mechanisms in different populations and the development of more efficient and precision synthetic therapeutic strategies.

Globally Approved EGFR Inhibitors: Insights into Their Syntheses, Target Kinases, Biological Activities, Receptor Interactions, and Metabolism

Targeting the EGFR with small-molecule inhibitors is a confirmed valid strategy in cancer therapy. Since the FDA approval of the first EGFR-TKI, erlotinib, great efforts have been devoted to the discovery of new potent inhibitors. Until now, fourteen EGFR small-molecule inhibitors have been globally approved for the treatment of different types of cancers. Although these drugs showed high efficacy in cancer therapy, EGFR mutations have emerged as a big challenge for these drugs. In this review, we focus on the EGFR small-molecule inhibitors that have been approved for clinical uses in cancer therapy. These drugs are classified based on their chemical structures, target kinases, and pharmacological uses. The synthetic routes of these drugs are also discussed. The crystal structures of these drugs with their target kinases are also summarized and their bonding modes and interactions are visualized. Based on their binding interactions with the EGFR, these drugs are also classified into reversible and irreversible inhibitors. The cytotoxicity of these drugs against different types of cancer cell lines is also summarized. In addition, the proposed metabolic pathways and metabolites of the fourteen drugs are discussed, with a primary focus on the active and reactive metabolites. Taken together, this review highlights the syntheses, target kinases, crystal structures, binding interactions, cytotoxicity, and metabolism of the fourteen globally approved EGFR inhibitors. These data should greatly help in the design of new EGFR inhibitors.

Icotinib, Almonertinib, and Olmutinib: A 2D Similarity/Docking-Based Study to Predict the Potential Binding Modes and Interactions into EGFR

In the current study, a 2D similarity/docking-based study was used to predict the potential binding modes of icotinib, almonertinib, and olmutinib into EGFR. The similarity search of icotinib, almonertinib, and olmutinib against a database of 154 EGFR ligands revealed the highest similarity scores with erlotinib (0.9333), osimertinib (0.9487), and WZ4003 (0.8421), respectively. In addition, the results of the docking study of the three drugs into EGFR revealed high binding free energies (ΔG_b = −6.32 to −8.42 kcal/mol) compared to the co-crystallized ligands (ΔG_b = −7.03 to −8.07 kcal/mol). Analysis of the top-scoring poses of the three drugs was done to identify their potential binding modes. The distances between Cys797 in EGFR and the Michael acceptor sites in almonertinib and olmutinib were determined. In conclusion, the results could provide insights into the potential binding characteristics of the three drugs into EGFR which could help in the design of new more potent analogs.

Reactivities of the Front Pocket N-Terminal Cap Cysteines in Human Kinases

The front pocket (FP) N-terminal cap (Ncap) cysteine is the most popular site of covalent modification in kinases. A long-standing hypothesis associates the Ncap position with cysteine hyper-reactivity; however, traditional computational predictions suggest that the FP Ncap cysteines are predominantly unreactive. Here we applied the state-of-the-art continuous constant pH molecular dynamics (CpHMD) to test the Ncap hypothesis. Simulations found that the Ncap cysteines of BTK/BMX/TEC/ITK/TXK, JAK3, and MKK7 are reactive to varying degrees; however, those of BLK and EGFR/ERBB2/ERBB4 possessing a Ncap+3 aspartate are unreactive. Analysis suggested that hydrogen bonding and electrostatic interactions drive the reactivity, and their absence renders the Ncap cysteine unreactive. To further test the Ncap hypothesis, we examined the FP Ncap+2 cysteines in JNK1/JNK2/JNK3 and CASK. Our work offers a systematic understanding of the cysteine structure-reactivity relationship and illustrates the use of CpHMD to differentiate cysteines toward the design of targeted covalent inhibitors with reduced chemical reactivities.

Small Molecule Kinase Inhibitor Drugs (1995-2021): Medical Indication, Pharmacology, and Synthesis

The central role of dysregulated kinase activity in the etiology of progressive disorders, including cancer, has fostered incremental efforts on drug discovery programs over the past 40 years. As a result, kinase inhibitors are today one of the most important classes of drugs. The FDA approved 73 small molecule kinase inhibitor drugs until September 2021, and additional inhibitors were approved by other regulatory agencies during that time. To complement the published literature on clinical kinase inhibitors, we have prepared a review that recaps this large data set into an accessible format for the medicinal chemistry community. Along with the therapeutic and pharmacological properties of each kinase inhibitor approved across the world until 2020, we provide the synthesis routes originally used during the discovery phase, many of which were only available in patent applications. In the last section, we also provide an update on kinase inhibitor drugs approved in 2021.

Mechanisms and management of 3rd‑generation EGFR‑TKI resistance in advanced non‑small cell lung cancer (Review)

Targeted therapy with epidermal growth factor receptor (EGFR)‑tyrosine kinase inhibitors (TKIs) is a standard modality of the 1st‑line treatments for patients with advanced EGFR‑mutated non‑small cell lung cancer (NSCLC), and substantially improves their prognosis. However, EGFR T790M mutation is the primary mechanism of 1st‑ and 2nd‑generation EGFR‑TKI resistance. Osimertinib is a representative of the 3rd‑generation EGFR‑TKIs that target T790M mutation, and has satisfactory efficacy in the treatment of T790M‑positive NSCLC with disease progression following use of 1st‑ or 2nd‑generation EGFR‑TKIs. Other 3rd‑generation EGFR‑TKIs, such as abivertinib, rociletinib, nazartinib, olmutinib and alflutinib, are also at various stages of development. However, the occurrence of acquired resistance is inevitable, and the mechanisms of 3rd‑generation EGFR‑TKI resistance are complex and incompletely understood. Genomic studies in tissue and liquid biopsies of resistant patients reveal multiple candidate pathways. The present review summarizes the recent findings in mechanisms of resistance to 3rd‑generation EGFR‑TKIs in advanced NSCLC, and provides possible strategies to overcome this resistance. The mechanisms of acquired resistance mainly include an altered EGFR signaling pathway (EGFR tertiary mutations and amplification), activation of aberrant bypassing pathways (hepatocyte growth factor receptor amplification, human epidermal growth factor receptor 2 amplification and aberrant insulin‑like growth factor 1 receptor activation), downstream pathway activation (RAS/RAF/MEK/ERK and PI3K/AKT/mTOR) and histological/phenotypic transformations (SCLC transformation and epithelial‑mesenchymal transition). The combination of targeted therapies is a promising strategy to treat osimertinib‑resistant patients, and multiple clinical studies on novel combined therapies are ongoing.

Recent Advances in BTK Inhibitors for the Treatment of Inflammatory and Autoimmune Diseases

Bruton’s tyrosine kinase (BTK) plays a crucial role in B-cell receptor and Fc receptor signaling pathways. BTK is also involved in the regulation of Toll-like receptors and chemokine receptors. Given the central role of BTK in immunity, BTK inhibition represents a promising therapeutic approach for the treatment of inflammatory and autoimmune diseases. Great efforts have been made in developing BTK inhibitors for potential clinical applications in inflammatory and autoimmune diseases. This review covers the recent development of BTK inhibitors at preclinical and clinical stages in treating these diseases. Individual examples of three types of inhibitors, namely covalent irreversible inhibitors, covalent reversible inhibitors, and non-covalent reversible inhibitors, are discussed with a focus on their structure, bioactivity and selectivity. Contrary to expectations, reversible BTK inhibitors have not yielded a significant breakthrough so far. The development of covalent, irreversible BTK inhibitors has progressed more rapidly. Many candidates entered different stages of clinical trials; tolebrutinib and evobrutinib are undergoing phase 3 clinical evaluation. Rilzabrutinib, a covalent reversible BTK inhibitor, is now in phase 3 clinical trials and also offers a promising future. An analysis of the protein–inhibitor interactions based on published co-crystal structures provides useful clues for the rational design of safe and effective small-molecule BTK inhibitors.

New thieno[3,2-d]pyrimidine-based derivatives: Design, synthesis and biological evaluation as antiproliferative agents, EGFR and ARO inhibitors inducing apoptosis in breast cancer cells

An array of newly synthesized thieno[3,2-d]pyrimidine-based derivatives and thienotriazolopyrimidines hybridized with some pharmacophoric anticancer fragments were designed, synthesized and assessed for their in vitro antiproliferative activity against MCF-7 and MDA-MB-231 breast cancer cell lines using erlotinib and pictilisib as reference standards in the MTT assay. In general, many compounds were endowed with considerable antiproliferative activity (IC₅₀ = 0.43-1.31 µM). Some of the tested compounds, namely 3c, 5b, 5c, 9d, 10, 11b and 13 displayed remarkable antiproliferative activity against both cell lines. Meanwhile, compounds 2c-e, 3b, 4a, 5a, 9c and 15b showed noticeable selectivity against MCF-7 cells while compounds 2b, 3a, 4b, 6a-c, 7, 8, 9b and 12 exhibited considerable selectivity against MDA-MB-231 cells. Further mechanistic evidences for their anticancer activities were provided by screening the most potent compounds against MCF-7 and/or MDA-MB-231 cells for EGFR and ARO inhibitory activities using erlotinib and letrozole as reference standards respectively. Results proved that, in general, tested compounds were better EGFRIs than ARIs. In addition, significant overexpression in caspase-9 level in treated MCF-7 breast cell line samples was observed for all tested compounds with the 4-fluorophenylhydrazone derivative 2d exhibiting the highest activation. In treated MDA-MB-231 breast cell line samples, 11b was found to highly induce caspase-9 level thereby inducing apoptosis. Cell cycle analysis and Annexin V-FITC/PI assay were also assessed for active compounds where results indicated that all tested compounds induced preG1 apoptosis and cell cycle arrest at G2/M phase. Compound 9d, as an inhibitor of ARO, was observed to downregulate the downstream signaling proteins HSP27 and p-ERK in MCF-7 cells. Furthermore, compound 11b downregulated EGFR expression as well as the downstream signaling protein p-AKT. Docking experiments on EGFR and ARO enzymes supported their in vitro results. Thus, the thienotriazolopyrimidines 11b and 12 showing good EGFR inhibition and the thieno[3,2-d]-pyrimidine derivatives 3b and 9d, eliciting the best ARO inhibition activity, can be considered as new candidates as anti-breast cancer agents that necessitate further development.

Btk Inhibitors: A Medicinal Chemistry and Drug Delivery Perspective

In the past few years, Bruton’s tyrosine Kinase (Btk) has emerged as new target in medicinal chemistry. Since approval of ibrutinib in 2013 for treatment of different hematological cancers (as leukemias and lymphomas), two other irreversible Btk inhibitors have been launched on the market. In the attempt to overcome irreversible Btk inhibitor limitations, reversible compounds have been developed and are currently under evaluation. In recent years, many Btk inhibitors have been patented and reported in the literature. In this review, we summarized the (ir)reversible Btk inhibitors recently developed and studied clinical trials and preclinical investigations for malignancies, chronic inflammation conditions and SARS-CoV-2 infection, covering advances in the field of medicinal chemistry. Furthermore, the nanoformulations studied to increase ibrutinib bioavailability are reported.

Kinase drug discovery 20 years after imatinib: progress and future directions

Protein kinases regulate nearly all aspects of cell life, and alterations in their expression, or mutations in their genes, cause cancer and other diseases. Here, we review the remarkable progress made over the past 20 years in improving the potency and specificity of small-molecule inhibitors of protein and lipid kinases, resulting in the approval of more than 70 new drugs since imatinib was approved in 2001. These compounds have had a significant impact on the way in which we now treat cancers and non-cancerous conditions. We discuss how the challenge of drug resistance to kinase inhibitors is being met and the future of kinase drug discovery.

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.

Targeting HSF1 as a Therapeutic Strategy for Multiple Mechanisms of EGFR Inhibitor Resistance in EGFR Mutant Non-Small-Cell Lung Cancer

Simple Summary

We attempted to identify target proteins and compounds that can be used to overcome EGFR-TKI resistance in NSCLC. To accomplish this, we generated EGFR inhibitor erlotinib-resistant HCC827-ErlR cells and obtained a list of differentially expressed genes. Then, we performed connectivity map analysis and identified heat shock factor 1 (HSF1) as a potential target protein to overcome erlotinib resistance. Using specific HSF1 shRNAs and KRIBB11 (N²-(1H-Indazol-5-yl)-N⁶-methyl-3-nitropyridine-2,6-diamine), we proved the effectiveness of HSF1 inhibition for overcoming erlotinib resistance in vitro. In addition, we proved the efficacy of emetine in inhibiting HSF1 activity and the tumor growth of erlotinib-resistant PC9-ErlR cells in a mouse model.

Abstract

Although EGFR-TKI treatment of NSCLC (non-small-cell lung cancer) patients often achieves profound initial responses, the efficacy is transient due to acquired resistance. Multiple receptor tyrosine kinase (RTK) pathways contribute to the resistance of NSCLC to first- and third-generation EGFR-TKIs, such as erlotinib and osimertinib. To identify potential targets for overcoming EGFR-TKI resistance, we performed a gene expression signature-based strategy using connectivity map (CMap) analysis. We generated erlotinib-resistant HCC827-ErlR cells, which showed resistance to erlotinib, gefitinib, osimertinib, and doxorubicin. A list of differentially expressed genes (DEGs) in HCC827-ErlR cells was generated and queried using CMap analysis. Analysis of the top 4 compounds from the CMap list suggested HSF1 as a potential target to overcome EGFR-TKI resistance. HSF1 inhibition by using HSF1 shRNAs or KRIBB11 decreased the expression of HSF1 downstream proteins, such as HSP70 and HSP27, and also decreased the expression of HSP90/HSP70/BAG3 client proteins, such as BCL2, MCL1, EGFR, MET, and AXL, causing apoptosis of EGFR-TKI-resistant cancer cells. Finally, we demonstrated the efficacy of the HSF1 inhibitor on PC9-ErlR cells expressing mutant EGFR (T790M) in vivo. Collectively, these findings support a targetable HSF1-(HSP90/HSP70/BAG3)-(BCL2/MCL1/EGFR/MET/AXL) pathway to overcome multiple mechanisms of EGFR-TKI resistance.

Small molecules in targeted cancer therapy: advances, challenges, and future perspectives

Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

The synthesis review of the approved tyrosine kinase inhibitors for anticancer therapy in 2015-2020

In the 21st century, cancer is the major public health problem worldwide. Based on the important roles of protein tyrosine kinase, the accelerated hunt for potent small-molecule tyrosine kinase inhibitors has led to the success of 30 newly inhibitors in this family for the cancer therapy in last five years. In this review, we updated their synthesis methods, and compared the original research routes with the optimized routes for each PTK inhibitor against different target, in order to make an outlook on the future synthesis of potential PTK inhibitors for anticancer therapy.

Design, Synthesis, and Antitumor Activity of Olmutinib Derivatives Containing Acrylamide Moiety

Two series of olmutinib derivatives containing an acrylamide moiety were designed and synthesized, and their IC₅₀ values against cancer cell lines (A549, H1975, NCI-H460, LO2, and MCF-7) were evaluated. Most of the compounds exhibited moderate cytotoxic activity against the five cancer cell lines. The most promising compound, H10, showed not only excellent activity against EGFR kinase but also positive biological activity against PI3K kinase. The structure–activity relationship (SAR) suggested that the introduction of dimethylamine scaffolds with smaller spatial structures was more favorable for antitumor activity. Additionally, the substitution of different acrylamide side chains had different effects on the activity of compounds. Generally, compounds H7 and H10 were confirmed as promising antitumor agents.

An update of new small-molecule anticancer drugs approved from 2015 to 2020

A high incidence of cancer has given rise to the development of more anti-tumor drugs. From 2015 to 2020, fifty-six new small-molecule anticancer drugs, divided into ten categories according to their anti-tumor target activities, have been approved. These include TKIs (30 drugs), MAPK inhibitors (3 drugs), CDK inhibitors (3 drugs), PARP inhibitors (3 drugs), PI3K inhibitors (3 drugs), SMO receptor antagonists (2 drugs), AR antagonists (2 drugs), SSTR inhibitors (2 drugs), IDH inhibitors (2 drugs) and others (6 drugs). Among them, PTK inhibitors (30/56) have led to a paradigm shift in cancer treatment with less toxicity and more potency. Each of their structures, approval statuses, applications, SAR analyses, and original research synthesis routes have been summarized, giving us a more comprehensive map for further efforts to design more specific targeted agents for reducing cancer in the future. We believe this review will help further research of potential antitumor agents in clinical usage.

FDA-approved pyrimidine-fused bicyclic heterocycles for cancer therapy: Synthesis and clinical application

Considerable progress has been made in the development of anticancer agents over the past few decades, and a lot of new anticancer agents from natural and synthetic sources have been produced. Among heterocyclic compounds, pyrimidine-fused bicyclic heterocycles possess a variety of biological activities such as anticancer, antiviral, etc. To date, 147 pyrimidine-fused bicyclic heterocycles have been approved for clinical assessment or are currently being used in clinic, 57 of which have been approved by FDA for clinical treatment of various diseases, and 22 of them are being used in the clinic for the treatment of different cancers. As the potentially privileged scaffolds, pyrimidine-fused bicyclic heterocycles may be used to discover new drugs with similar biological targets and improved therapeutic efficacy. This review aims to provide an overview of the anticancer applications and synthetic routes of 22 approved pyrimidine-fused bicyclic heterocyclic drugs in clinic.

Advances in Lung Cancer Driver Genes Associated With Brain Metastasis

Brain metastasis, one of the common complications of lung cancer, is an important cause of death in patients with advanced cancer, despite progress in treatment strategies. Lung cancers with positive driver genes have higher incidence and risk of brain metastases, suggesting that driver events associated with these genes might be biomarkers to detect and prevent disease progression. Common lung cancer driver genes mainly encode receptor tyrosine kinases (RTKs), which are important internal signal molecules that interact with external signals. RTKs and their downstream signal pathways are crucial for tumor cell survival, invasion, and colonization in the brain. In addition, new tumor driver genes, which also encode important molecules closely related to the RTK signaling pathway, have been found to be closely related to the brain metastases of lung cancer. In this article, we reviewed the relationship between lung cancer driver genes and brain metastasis, and summarized the mechanism of driver gene-associated pathways in brain metastasis. By understanding the molecular characteristics during brain metastasis, we can better stratify lung cancer patients and alert those at high risk of brain metastasis, which helps to promote individual therapy for lung cancer.

Design, synthesis and evaluation of novel ErbB/HDAC multitargeted inhibitors with selectivity in EGFRT790M mutant cell lines

Acquired resistance leads to the failure of EGFR TKIs in NSCLC treatment. A novel series of hydroxamic acid-containing 4-aminoquinazoline derivatives as irreversible ErbB/HDAC multitargeted inhibitors for NSCLC therapy had been designed and synthesized, which displayed weak anti-proliferative activity in several EGFR wild-type cancer cell lines (NCI-H838, SK-BR-3, A549, A431) yet retained moderate activity to EGFR^T790M resistance mutation harboring NCI-H1975 cells. The mechanistic studies revealed that the representative compound 11e was able to inhibit the phosphorylation of EGFR, up-regulate hyperacetylation of histone H3 and even reduce the expression of EGFR and Akt in NCI-H1975 cells. In further assays, compound 11e also showed moderate anti-proliferative activity in other EGFR^T790M harboring tumor cell lines (NCI-H820, Ba/F3_EGFR_Del19-T790M-C797S) and low toxicities in normal cell lines (HL-7702, FHC). This selectivity of designed multitargeted compounds could serve as a potential strategy to circumvent multiple mechanisms of acquired resistance to EGFR-targeted therapy without severe toxicities and side effects resulting from broad inhibition.