Surmounting the resistance against EGFR inhibitors through the development of thieno[2,3-d]pyrimidine-based dual EGFR/HER2 inhibitors

Unraveling the future: Innovative design strategies and emerging challenges in HER2-targeted tyrosine kinase inhibitors for cancer therapy

Human epidermal growth factor receptor 2 (HER2) is a transmembrane receptor-like protein with tyrosine kinase activity that plays a vital role in processes such as cell proliferation, differentiation, and angiogenesis. The degree of malignancy of different cancers, notably breast cancer, is strongly associated with HER2 amplification, overexpression, and mutation. Currently, widely used clinical HER2 tyrosine kinase inhibitors (TKIs), such as lapatinib and neratinib, have several drawbacks, including susceptibility to drug resistance caused by HER2 mutations and adverse effects from insufficient HER2 selectivity. To address these issues, it is essential to create innovative HER2 TKIs with enhanced safety, effectiveness against mutations, and high selectivity. Typically, SPH5030 has advanced to phase I clinical trials for its strong suppression of four HER2 mutations. This review discusses the latest research progress in HER2 TKIs, with a focus on the structural optimization process and structure-activity relationship analysis. In particular, this study highlights promising design strategies to address these challenges, providing insightful information and inspiration for future development in this field.

A decade's overview of 2-aminothiophenes and their fused analogs as promising anticancer agents

Over the past decades, cancer has been a challenging domain for medicinal chemists as it is an international health concern. In association, small molecules such as 2-aminothiophenes and their derivatives showed significant antitumor activity through variable modes of action. Therefore, this article aims to review the advances regarding these core scaffolds over the past 10 years, where 2-aminothiophenes and their fused analogs are classified and discussed according to their biological activity and mode of action, in the interest of boosting new design pathways for medicinal chemists to develop targeted antitumor candidates.

An assessment of EGFR and HER2 inhibitors with structure activity relationship of fused pyrimidine derivatives for breast cancer: a brief review

Epidermal growth factor receptor (EGFR) and its subtype human epidermal growth factor receptor 2 (HER2) gets activated when its endogenous ligand(s) bind to its ATP binding site of target receptors. In breast cancer (BC), EGFR and HER2 are two proteins are overexpressed which leads to overexpression of cells proliferation and decreases cell death/apoptosis. Pyrimidine is one of the most widely studied heterocyclic scaffolds for EGFR as well as HER2 inhibition. We gather some remarkable results for fused-pyrimidine derivatives on various cancerous cell lines (in-vitro) and animal (in-vivo) evaluation to highlight their potency. The heterocyclic (five, six-membered, etc.) moieties which are coupled with pyrimidine moiety are potent against EGFR and HER2 inhibitions. Hence structure-activity relationship (SAR) plays important role in study of heterocyclic moiety along pyrimidine and effects of substituents, groups for increase or decrease in the cancerous activity and toxicity. By thoughtful of fused pyrimidines SAR study, it facilitates in receiving excellent overview of the compounds by concerning of efficacy and potential summary for future EGFR inhibitors. Furthermore, we studied the in-silico interactions of synthesized compounds to evaluate binding affinity towards the key amino acids..Communicated by Ramaswamy H. Sarma.

Recent updates on thienopyrimidine derivatives as anticancer agents

Thienopyrimidine derivatives hold a unique place between fused pyrimidine compounds. They are important and widely represented in medicinal chemistry as they are structural analogs of purines. Thienopyrimidine derivatives have various biological activities. The current review discusses different synthetic methods for the preparation of heterocyclic thienopyrimidine derivatives. It also highlights the most recent research on the anticancer effects of thienopyrimidines through the inhibition of various enzymes and pathways, which was published within the last 9 years.

Graphical Abstract

Privileged Scaffolds in Drug Discovery against Human Epidermal Growth Factor Receptor 2 for Cancer Treatment

HER2 is the membrane receptor tyrosine kinase showing overexpression in several human malignancies, particularly breast cancer. HER2 overexpression causes the activation of Ras- MAPK and PI3K/Akt/ NF-κB cellular signal transduction pathways that lead to cancer development and progression. HER2 is, therefore, presumed as one of the key targets for the development of tumor-specific therapies. Several preclinical have been developed that function by inhibiting the HER2 tyrosine kinase activity through the prevention of the dimerization process. Most HER2 inhibitors act as ATP competitors and prevent the process of phosphorylation, and abort the cell cycle progression and proliferation. In this review, the clinical drug candidates and potent pre-clinical newly developed molecules are described, and the core chemical scaffolds typically responsible for anti-HER2 activity are deciphered. In addition, the monoclonal antibodies that are either used in monotherapy or in combination therapy against HER2-positive cancer are briefly described. The identified key moieties in this study could result in the discovery of more effective HER2-targeted anticancer drug molecules and circumvent the development of resistance by HER2-specific chemotherapeutics in the future.

Terminal Phenoxy Group as a Privileged Moiety of the Drug Scaffold—A Short Review of Most Recent Studies 2013–2022

The terminal phenoxy group is a moiety of many drugs in use today. Numerous literature reports indicated its crucial importance for biological activity; thus, it is a privileged scaffold in medicinal chemistry. This review focuses on the latest achievements in the field of novel potential agents bearing a terminal phenoxy group in 2013–2022. The article provided information on neurological, anticancer, potential lymphoma agent, anti-HIV, antimicrobial, antiparasitic, analgesic, anti-diabetic as well as larvicidal, cholesterol esterase inhibitors, and antithrombotic or agonistic activities towards the adrenergic receptor. Additionally, for selected agents, the Structure–Activity–Relationship (SAR) is also discussed. Thus, this study may help the readers to better understand the nature of the phenoxy group, which will translate into rational drug design and the development of a more efficient drug. To the best of our knowledge, this is the first review devoted to an in-depth analysis of the various activities of compounds bearing terminal phenoxy moiety.

Pyrimidine derivatives as EGFR tyrosine kinase inhibitors in NSCLC: - A comprehensive review

EGFR positive NSCLC due to primary mutation (EGFR DEL19 & L858R) has been recognized as a crucial mediator of tumor progression. This led to the development and approval of EGFR tyrosine kinase inhibitors which addresses EGFR mediated NSCLC but fail to show potency after initial months of therapy due to acquired resistance (EGFR T790M, EGFR C797S). Extensive research allowed identification of drugs for EGFR positive NSCLC, wherein the majority of compounds have a pyrimidine substructure offering marked therapeutic benefits compared to chemotherapy. This current review outlines the diverse pyrimidine derivatives with amino-linked and fused pyrimidine scaffolds such as furo-pyrimidine, pyrimido-pyrimidine, thieno-pyrimidine, highlighting pyrimidine EGFR TK inhibitors reported in research emphasizing structural aspects, design approaches, inhibition potential. selectivity profile towards mutant EGFR conveyed through biological evaluation studies. Furthermore, mentioning the in-silico interaction profile of synthesized compounds for evaluating the binding affinity with key amino acids. The epilogue of review focuses on the recent research that drives forward to aid in the discovery and development of substituted amino and fused scaffolds of pyrimidine that can counteract the mutations and effectively manage EGFR positive NSCLC.

Synthesis, Molecular Docking Study, and Cytotoxic Activity against MCF Cells of New Thiazole–Thiophene Scaffolds

Investigating novel compounds that may be useful in designing new, less toxic, selective, and potent breast anticancer agents is still the main challenge for medicinal chemists. Thus, in the present work, acetylthiophene was used as a building block to synthesize a novel series of thiazole-bearing thiophene derivatives. The structures of the synthesized compounds were elucidated based on elemental analysis and spectral measurements. The cytotoxic activities of the synthesized compounds were evaluated against MCF-7 tumor cells and compared to a cisplatin reference drug, and against the LLC-Mk2 normal cell line using the MTT assay, and the results revealed promising activities for compounds 4b and 13a. The active compounds were subjected to molecular modeling using MOE 2019, the pharmacokinetics were studied using SwissADME, and a toxicity radar was obtained from the biological screening data. The results obtained from the computational studies supported the results obtained from the anticancer biological studies.

Synthesis and biological evaluation of new series of quinazoline derivatives as EGFR/HER2 dual-target inhibitors

It is generally believed that EGFR/HER2 dual-target inhibitors may overcome the resistance of EGFR TKIs caused by HER2 overexpression. The structure-based synthesis and biological evaluation of quinazoline derivatives as EGFR/HER2 dual-target inhibitors has been studied in this paper. II-1, II-2, III-3, III-4 displayed comparable inhibitory potency against EGFR and HER2 and II-1 showed remarkable antiproliferative activities against NCI-H358/PC-9/Calu-3/NCI-H1781 (EGFR IC₅₀ = 0.30 nM, HER2 IC₅₀ = 6.07 nM, NCI-H358 GI₅₀ = 23.30 nM, PC-9 GI₅₀ = 1.95 nM, Calu-3 GI₅₀ = 23.13 nM NCI-H1781 GI₅₀ = 41.61 nM).

A Review on Fused Pyrimidine Systems as EGFR Inhibitors and Their Structure–Activity Relationship

Epidermal growth factor receptor (EGFR) belongs to the family of tyrosine kinase that is activated when a specific ligand binds to it. The EGFR plays a vital role in the cellular proliferation process, differentiation, and apoptosis. In the case of cancer, EGFR undergoes uncontrolled auto-phosphorylation that results in increased cellular proliferation and decreased apoptosis, causing cancer promotion. From the literature, it shows that pyrimidine is one of the most commonly studied heterocycles for its antiproliferative activity against EGFR inhibition. The authors have collated some interesting results in the heterocycle-fused pyrimidines that have been studied using different cell lines (sensitive and mutational) and in animal models to determine their activity and potency. It is quite clear that the fused systems are highly effective in inhibiting EGFR activity in cancer cells. Therefore, the structure–activity relationship (SAR) comes into play in determining the nature of the heterocycle and the substituents that are responsible for the increased activity and toxicity. Understanding the SAR of heterocycle-fused pyrimidines will help in getting a better overview of the molecules concerning their activity and potency profile as future EGFR inhibitors.

Preclinical activity of fluvastatin-loaded self-nanoemulsifying delivery system against breast cancer models: Emphasis on apoptosis

Statins trigger apoptotic cell death in some types of growing tumor cells in a cholesterol-lowering-independent manner. Self-nanoemulsifying delivery systems (SNEDs) are potentially effective for the suppression of breast cancer development. This study aims to investigate the potential anticancer activity of fluvastatin (FLV)-SNEDs in breast cancer while comparing it with FLV in vitro as well as in vivo exploiting/using MDA-MB-231 and Erhlich ascites carcinoma (EAC)-bearing mice, respectively. Biochemical analysis of liver and kidney functions, oxidative stress markers, and histopathological examinations of such tumor tissues were performed showing the potentiality of SNEDs as a nanocarrier for antitumor agents. FLV-SNEDs demonstrated more potent anticancer activity compared to FLV on MDA-MB-231 and hepatocellular carcinoma (HepG2) cells. In vivo experiments on the EAC-bearing mice model indicated that FLV and-to a greater extent-FLV-SNEDs ameliorated EAC-induced hepatotoxicity and nephrotoxicity. FLV or FLV-SNEDs evidently reduced the percent of Ki-67 +ve EAC cells by 57.5% and 86.5% in comparison to the vehicle-treated EAC group. In addition, FLV or FLV-SNEDs decreased Bcl-2 levels in serum and liver specimens. In contrast, FLV or FLV-SNEDs significantly activated the executioner caspase-3. Simultaneously, both FLV and FLV-SNEDs stimulated p53 signaling and modulated Bcl-2 protein levels in treated cells. Collectively, these results support the contribution of apoptotic cell death in mediating the anticancer activities of FLV and FLV-SNEDs against murine EAC model in vivo. This study provides new understandings of how FLV and FLV-SNEDs regulate EAC cell viability via upregulation of p53 signaling, and through modulation of cleaved caspase-3 as well as antiapoptotic Bcl-2 marker.

Synthesis, and docking studies of novel heterocycles incorporating the indazolylthiazole moiety as antimicrobial and anticancer agents

The current study was directed toward developing a new series of fused heterocycles incorporating indazolylthiazole moiety. The newly synthesized compounds were characterized through elemental analysis and spectral data (IR, 1H-NMR, 13C-NMR, and Mass Spectrometry). The cytotoxic effect of the newly synthesized compounds was evaluated against normal human cells (HFB-4) and cancer cell lines (HepG-2 and Caco-2). Among the synthesized compounds, derivatives 4, and 6 revealed a significant selective antitumor activity, in a dose-dependent manner, against both HepG-2 and Caco-2 cell lines, with lower risk toward HFB-4 cells (normal cells). Derivative 8 revealed the maximum antitumor activity toward both tumor cell lines, with an SI value of about 26 and IC50 value of about 5.9 μg/mL. The effect of these derivatives (8, 4, and 6) upon the expression of 5 tumor regulating genes was studied through quantitative real-time PCR, where its interaction with these genes was simulated through the molecular docking study. Furthermore, the antimicrobial activity results revealed that compounds 2, 7, 8, and 9 have a potential antimicrobial activity, with maximum broad-spectrum activity through compound 3 against the three tested pathogens: Streptococcus mutans, Pseudomonas aeruginosa, and Candida albicans. The newly prepared compounds also revealed anti-biofilm formation activity with maximum activity against Streptococcus mutans, Pseudomonas aeruginosa, and Candida albicans, respectively.

Integration of rapid PCR testing as an adjunct to NGS in diagnostic pathology services within the UK: evidence from a case series of non-squamous, non-small cell lung cancer (NSCLC) patients with follow-up

AIMS

Somatic genetic testing in non-squamous, non-small cell lung carcinoma (NSCLC) patients is required to highlight subgroups eligible for a number of novel oncological therapies. This study aims to determine whether turnaround times for reporting epidermal growth factor receptors (EGFR) by next-generation sequencing (NGS) alone is sufficient to meet the needs of lung cancer patients.

METHODS

We performed a retrospective case series with follow-up. Outcomes of EGFR testing (102 tests) in 96 patients by NGS were compared with a rapid, fully automated PCR-based platform (Idylla) in local histopathology laboratories.

RESULTS

Turnaround time for reporting NGS was 17 calendar days. Reporting using the Idylla EGFR Mutation Test, by contrast, gave a potential turnaround time of 3.8 days from request to authorisation. Three-quarters of patients presenting with stage IV disease had a performance status of 0, 1, or 2 but 18% experienced rapid clinical deterioration (p<0.05). A third of these patients were deceased by the time NGS reports were available.

CONCLUSIONS

We discuss issues around integrating rapid PCR testing alongside NGS in multidisciplinary care pathways and strategies for mitigating against foreseeable difficulties. Dual testing for stage IV non-squamous, NSCLC patients has the potential to improve care and survival outcomes by providing access to the right test at the right time.

EGFRisopred: a machine learning-based classification model for identifying isoform-specific inhibitors against EGFR and HER2

The EGFR kinase pathway is one of the most frequently activated signaling pathways in human cancers. EGFR and HER2 are the two significant members of this pathway, which are attractive drug targets of clinical relevance in lung and breast cancer. Therefore, identifying EGFR- and HER2-specific inhibitors is one of the important challenges in cancer drug discovery. To address this issue, a dataset of 519 compounds having inhibitory activity against both the isoforms, i.e., EGFR and HER2, was collected from the literature and developed a knowledge-based computational classification model for predicting the specificity of a molecule for an isoform (EGFR/HER2) with precision. A total of seventy-two classification models using nine fingerprint types, four classifiers (IBK, NB, SMO and RF) and two different datasets (EGFR and HER2 isoform specific) were developed. It was observed that the models developed using random forest and IBK performed better for EGFR- and HER2-specific datasets, respectively. Scaffold and functional group analysis led to the identification of prevalent core and fragments in each of the datasets. The accuracy of the selected best performing models was also evaluated using the decoy dataset. We have also developed an application EGFRisopred, which integrates the best performing models and permits the user to predict the specificity of a compound as an EGFR-/HER2-specific anticancer agent. It is expected that the tool's availability as a free utility will allow researchers to identify new inhibitors against these targets important in cancer.

Discovery of novel and potent safinamide-based derivatives as highly selective hMAO-B inhibitors for treatment of Parkinson's disease (PD): Design, synthesis, in vitro, in vivo and in silico biological studies

Up to date, the current clinical practice employs only symptomatic treatments for management of Parkinson's disease (PD) but unable to stop disease progression. The discovery of new chemical entities endowed with potent and selective human monoamine oxidase B (hMAO-B) inhibitory activity is a clinically relevant subject. Herein, a structural optimization strategy for safinamide (a well-known second generation hMAO-B inhibitor) afforded a series of thirty-six safinamide-derived new analogs (4aa-bj). Most compounds showed promising inhibitory activities against hMAO-B (>70% inhibition at a single dose concentration of 10 µM), with no apparent effect on hMAO-A at 100 μM. Moreover, while six compounds (4ak, 4as, 4az, 4be, 4bg, and 4bi) exhibited potent double-digit nanomolar activities over hMAO-B with IC₅₀ values of 29.5, 42.2, 22.3, 18.8, 42.2, and 33.9 nM, respectively, three derivatives (4aq, 4at, and 4bf), possessing the same carboxamide moiety (2-pyrazinyl), showed the most potent single-digit nanomolar activities (IC₅₀ = 9.7, 5.1, and 3.9 nM, respectively). Compound 4bf revealed an excellent selectivity index (SI > 25641) with a 29-fold increase compared to safinamide (SI > 892). A structure activity relationship along with molecular docking simulations provided insights into enzyme - inhibitor interactions and a rational for the observed activity. In an in vivo MPTP-induced mouse model of PD, oral administration of compound 4bf significantly protected nigrostriatal dopaminergic neurons as revealed by tyrosine hydroxylase staining and prevented MPTP-induced Parkinsonism as revealed by motor behavioral assays. Accordingly, we present compound 4bf as a novel, highly potent, and selective hMAO-B inhibitor with an effective therapeutic profile for relieving PD.

Design, synthesis, and biological evaluation of N-(4-substituted)-3-phenylisoxazolo[5,4-d]pyrimidin-4-amine derivatives as apoptosis-inducing cytotoxic agents

A library of new 3-phenylisoxazolo[5,4-d]pyrimidines (8-10) was designed based on a scaffold hybridization technique incorporating the important pharmacophoric features of 4-aminopyrimidine and phenyl isoxazole scaffold which is renowned for its BET inhibition activity. The designed molecules were synthesized and evaluated with the NCI-60 cell line panel. Examination by NCI-60 cell lines at single-dose and the five-dose study showed that compound 10h exhibited promising growth inhibitory effects with GI₅₀ values on various cancer cell lines such as HCT-15 (Colon Cancer)-0.0221 μM, MDA-MB-435 (Melanoma) - 0.0318 μM, SNB-75(CNS Cancer)-0.0263 μM, and MCF7 (Breast Cancer)-0.0372 μM. Further studies to know the mechanism of action of 10h based on the phase-contrast microscopic evaluation, DAPI, acridine orange/ethidium bromide (AO/EB) staining, and annexin V-FITC assays revealed that elevation in the intracellular ROS leads to alteration in mitochondrial membrane potential which in turn induced the apoptosis in BT-474 cancer cells, which could be the plausible mechanism of action for compound 10h.

Rational design-aided discovery of novel 1,2,4-oxadiazole derivatives as potential EGFR inhibitors

A molecular dynamics-based sampling of epidermal growth factor receptor tyrosine kinase (EGFR-TK) was carried out to search for energetically more stable protein, which was then used for molecular docking of a series of 1,2,4-oxadiazole derivatives previously reported from our laboratory. A total of 14 compounds were docked, where compounds 6a and 6b showed better binding to EGFR in silico. Further, physicochemical properties of all the compounds were calculated, which suggested that all the molecules obeyed Lipinski's rule of 5 and had favorable polar surface area and CaCO2 permeability along with the low potential for HERG inhibition. All the compounds were then screened for their ability to produce cytotoxicity in four different cell lines overexpressing EGFR (A549, HCT-116, HEPG2, MCF-7) and one EGFR negative cancer cell line (SW620); at three concentrations: 10, 1, and 0.1 µM. None of the compounds showed activity against SW620, which suggested that the compounds show cytotoxicity through inhibition of EGFR. Compounds that showed promise in this 3-concentration screen were further subjected to multiple dose-response curves to identify the IC₅₀ values for the shortlisted eight compounds. It was encouraging to see 6a and 6b showing the best IC₅₀ values against almost all the cell-lines which further suggests that our design protocol can be applied to optimize this lead (which are currently in the low micromolar range) to design the homologous compounds to achieve the desired potency in the nanomolar range and also to achieve selectivity across a range of kinases.

Involvement of cancer-derived EMT cells in the accumulation of 18F-fluorodeoxyglucose in the hypoxic cancer microenvironment

A high rate of glycolysis, one of the most common features of cancer, is used in positron emission tomography (PET) imaging to visualize tumor tissues using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG). Heterogeneous intratumoral distribution of ¹⁸F-FDG in tissues has been established in some types of cancer, and the maximum standardized uptake value (SUVmax) has been correlated with poor prognosis. However, the phenotype of cells that show high ¹⁸F-FDG accumulation in tumors remains unknown. Here, we combined quantitative micro-autoradiography with fluorescence immunohistochemistry to simultaneously visualize ¹⁸F-FDG distribution, the expression of multiple proteins, and hypoxic regions in the cancer microenvironment of a human A431 xenograft tumor in C.B-17/Icr-scid/scid mice. We found that the highest ¹⁸F-FDG accumulation was in cancer-derived cells undergoing epithelial-mesenchymal transition (EMT) in hypoxic regions, implicating these regions as a major contributor to increased glucose metabolism, as measured by ¹⁸F-FDG-PET.

Pyrimidine-based EGFR TK inhibitors in targeted cancer therapy

Despite significant improvements of new treatment options, cancer continues to represent as one of the most common and fatal disease. The EGFR signaling pathway is considered as a significant approach in targeted therapy of cancers. Blocking the EGFR-driven pathway by inhibiting the intracellular tyrosine kinase domain of EGFR have shown considerable improvement in cancer therapy. In an effort to identify EGFR tyrosine kinase inhibitors (TKI), several small molecules especially pyrimidine containing derivatives have been designed by applying molecular simulation and evaluated the emergence of epigenetic mutation and resistance problems restricted the long-term effectiveness of such medication and explained the need for further investigations in this field. In recent years, the studies have been focused on genetic alterations on EGFR tyrosine kinase domain, which led to the design and synthesis of more selective and effective inhibitors. Herein, we give an overview of the importance and status of EGFR inhibitors in cancer therapy. In addition, we provide an update of the recent advances in design, discovery and development of novel pyrimidine containing compounds as promising selective EGFR TK inhibitors.

Design, synthesis, biological evaluation and docking study of novel quinazoline derivatives as EGFR-TK inhibitors

Background: Quinazoline-based compounds have been proved effective in the treatment of cancers for years. Materials & methods: The structural features of several inhibitors of EGFR were integrated and quinazolines with a benzazepine moiety at the 4-position were constructed. Results: Most of the compounds exhibited excellent antitumor activities. Compound 33e showed excellent antitumor activities against the four tested cell lines (IC₅₀: 1.06-3.55 μM). The enzymatic, signaling pathways and apoptosis assay of 33e were subsequently carried out to study the action of the mechanism. Conclusion: Compound 33e with a benzazepine moiety at the 4-position can be screened in this study and provides useful information for the design of EGFR-T790M inhibitors, which deserve additional research.

Thiazole-Based Thiosemicarbazones: Synthesis, Cytotoxicity Evaluation and Molecular Docking Study

INTRODUCTION

Hybrid drug design has developed as a prime method for the development of novel anticancer therapies that can theoretically solve much of the pharmacokinetic disadvantages of traditional anticancer drugs. Thus a number of studies have indicated that thiazole-thiophene hybrids and their bis derivatives have important anticancer activity. Mammalian Rab7b protein is a member of the Rab GTPase protein family that controls the trafficking from endosomes to the TGN. Alteration in the Rab7b expression is implicated in differentiation of malignant cells, causing cancer.

METHODS

1-(4-Methyl-2-(2-(1-(thiophen-2-yl) ethylidene) hydrazinyl) thiazol-5-yl) ethanone was used as building block for synthesis of novel series of 5-(1-(2-(thiazol-2-yl) hydrazono) ethyl) thiazole derivatives. The bioactivities of the synthesized compounds were evaluated with respect to their antitumor activities against MCF-7 tumor cells using MTT assay. Computer-aided docking protocol was performed to study the possible molecular interactions between the newly synthetic thiazole compounds and the active binding site of the target protein Rab7b. Moreover, the in silico prediction of adsorption, distribution, metabolism, excretion (ADME) and toxicity (T) properties of synthesized compounds were carried out using admetSAR tool.

RESULTS

The results obtained showed that derivatives 9 and 11b have promising activity (IC50 = 14.6 ± 0.8 and 28.3 ± 1.5 µM, respectively) compared to Cisplatin (IC50 = 13.6 ± 0.9 µM). The molecular docking analysis reveals that the synthesized compounds are predicted to be fit into the binding site of the target Rab7b. In summary, the synthetic thiazole compounds 1-17 could be used as potent inhibitors as anticancer drugs.

CONCLUSION

Promising anticancer activity of compounds 9 and 11 compared with cisplatin reference drug suggests that these ligands may contribute as lead compounds in search of new anticancer agents to combat chemo-resistance.

Pyrazolo[3,4-d]pyrimidine-based dual EGFR T790M/HER2 inhibitors: Design, synthesis, structure-activity relationship and biological activity as potential antitumor and anticonvulsant agents

A new series of pyrazolo[3,4-d]pyrimidine/triazine hybrids 6a-r was designed as antitumor and anticonvulsant agents. All the prepared compounds were evaluated against colon (HCT-116), breast (MCF-7) and normal human fibroblast (WI38) cell lines. The most potent derivatives against HCT-116 and MCF-7 cells were 6o and 6q, with IC₅₀ = 4.80 and 6.50 nM, respectively, when compared to lapatinib, the reference drug (IC₅₀ = 12.00 and 21.00 nM, on HCT-116 and MCF-7, sequentially). All other derivatives exhibited good to moderate cytotoxic activity. Four compounds 6f, 6j, 6o and 6q were evaluated for their EGFR T790M/HER2 inhibitory activity. They revealed 81.81-65.70% and 86.66-54.49% inhibitory activity against EGFR T790M and HER2 in a sequent. The most potent derivatives 6o and 6q were further estimated for cell cycle analysis showing pre G1 apoptotic activity and cell growth arrest at G2/M phase. Apoptotic marker proteins expression levels (caspase-3/7/9, Bax and Bcl-2) were measured for 6o and 6q. They showed pro-apoptotic effect by increasing caspase-3/7/9 protein levels and Bax/Bcl-2 ratio. Moreover, anticonvulsant activity for the prepared compounds 6a-r were evaluated in vivo using lithium-pilocarpine mice model of Status Epilepticus. EEG changes where recorded and MDA, GSH, GABA and glutamate were measured in brain tissue of different groups. All tested compounds revealed variable anti-epileptic effects, the most potent compounds were 6b and 6m. Also 6d, 6e, 6h, 6i, 6k, 6l and 6n compounds exhibited good anti-seizure activity, while compound 6j showed the lower activity. The rest of compounds displayed a neutral activity.

HER2 Kinase-Targeted Breast Cancer Therapy: Design, Synthesis, and In Vitro and In Vivo Evaluation of Novel Lapatinib Congeners as Selective and Potent HER2 Inhibitors with Favorable Metabolic Stability

HER2 kinase as a well-established target for breast cancer (BC) therapy is associated with aggressive clinical outcomes; thus, herein we present structural optimization for HER2-selective targeting. HER2 profiling of the developed derivatives demonstrated potent and selective inhibitions (IC₅₀: 5.4-12 nM) compared to lapatinib (IC₅₀: 95.5 nM). Favorably, 17d exhibited minimum off-target kinase activation. NCI-5-dose screening revealed broad-spectrum activities (GI₅₀: 1.43-2.09 μM) and 17d had a remarkable selectivity toward BC. Our compounds revealed significant selective and potent antiproliferative activities (∼20-fold) against HER2+ (AU565, BT474) compared to HER2(-) cells. At 0.1 IC₅₀, 15i, 17d, and 25b inhibited pERK1/2 and pAkt by immunoblotting. Furthermore, 17d demonstrated potent in vivo tumor regression against the BT474 xenograft model. Notably, a metastasis case was observed in the vehicle but not in the test mice groups. CD-1 mice metabolic stability assay revealed high stability and low intrinsic clearance of 17d (T_1/2 > 145 min and CL_int(mic) < 9.6 mL/min/kg).

Design, synthesis and antitumor activity of icotinib derivatives

EGFR-TK pathway is of high importance for the treatment of non-small-cell lung cancers (NSCLC), and it will be challenging to develop anti-tumor drugs that could inhibit both EGFR wild-type and mutant tumor cells. Here, a series of icotinib derivatives containing 1,2,3-triazole moiety were designed and synthesized through copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. Preliminary CCK-8 assay showed that the prepared icotinib-1,2,3-triazole compounds such as a7 or a12 demonstrated potent in vitro antitumor activity against the NSCLC cells expressing both wild type EGFR and mutational EGFR. Further, the mechanism of action for compounds a7 and a12 induced NSCLC cells death was also detailed, and the results suggested a possible induced NSCLC cells death via inducing mitochondrial apoptosis and arresting cell cycle. Remarkably, the inhibition of EGFR by these icotinib derivatives was also studied. The results showed that compound a12 was a potent inhibitor for EGFR with IC₅₀ value of 1.49 μM. Combining these results, an EGFR inhibitor a12 represents a promising new anti-NSCLC candidate that could induce apoptosis and arrest cell cycle.

Design, synthesis, and computational validation of novel compounds selectively targeting HER2-expressing breast cancer

Human epidermal growth factor receptor (HER) is a family of multidomain proteins that plays important role in the regulation of several biological functions. HER2 is a member of HER that is highly presented in breast cancer cells. Here, we designed and synthesized a series of diaryl urea/thiourea compounds. The compounds were tested on HER2⁺ breast cancer cells including MCF-7 and SkBr3, compared to HER2^- breast cancer cells including MDA-MB-231 and BT-549. Only compounds 12-14 at 10 µM showed selective anti-proliferative activity against MCF-7 and SkBr3 by 65-79%. Compounds 12-14 showed >80% inhibition of the intracellular kinase domain of HER2. The results obtained indicated that compounds 12-14 are selectively targeting HER2⁺ cells. The IC₅₀ of compound 13 against MCF-7 and SkBR3 were 1.3 ± 0.009 and 0.73 ± 0.03 µM, respectively. Molecular docking and MD simulations (50 ns) were carried out, and their binding free energies were calculated. Compounds 12-14 formed strong hydrogen bond and pi-pi stacking interactions with the key residues Thr862 and Phe864. 3DQSAR model confirmed the role of 3-bromo substituent of pyridine ring and 4-chloro substituent of phenyl ring in the activity of the compounds. In conclusion, novel compounds, particularly 13 were developed selectively against HER2-expressing/overexpressing breast cancer cells including MCF7 and SkBr3.

Diaryl Ether: A Privileged Scaffold for Drug and Agrochemical Discovery

Diaryl ether (DE) is a functional scaffold existing widely both in natural products (NPs) and synthetic organic compounds. Statistically, DE is the second most popular and enduring scaffold within the numerous medicinal chemistry and agrochemical reports. Given its unique physicochemical properties and potential biological activities, DE nucleus is recognized as a fundamental element of medicinal and agrochemical agents aimed at different biological targets. Its drug-like derivatives have been extensively synthesized with interesting biological features including anticancer, anti-inflammatory, antiviral, antibacterial, antimalarial, herbicidal, fungicidal, insecticidal, and so on. In this review, we highlight the medicinal and agrochemical versatility of the DE motif according to the published information in the past decade and comprehensively give a summary of the target recognition, structure-activity relationship (SAR), and mechanism of action of its analogues. It is expected that this profile may provide valuable guidance for the discovery of new active ingredients both in drug and pesticide research.

Development and Challenges of the Discovery of HER2 Inhibitors

The treatment of cancer has always been a major problem in the world. Some cancers cannot be treated with surgery, but only with cancer drugs. Among many cancer drugs, small molecule inhibitors play an irreplaceable role. HER2 is one of the HER families, and the development of HER2 inhibitors has made a huge contribution to the treatment of cancer. Some HER2 inhibitors are already on the market, and some HER2 inhibitors are undergoing clinical research. The design, synthesis and development of new HER2 inhibitors targeting different targets are also ongoing, and some are even under clinical research. The HER2 inhibitors that are on the market have developed resistance, which brings great challenges to the HER2 inhibitor development in the future. This article reviews the development and challenges of the discovery of HER2 inhibitors.

Thiophene-based derivatives as anticancer agents: An overview on decade's work

Heterocyclic compounds hold a pivotal place in medicinal chemistry due to their wide range of biological activities and thus, are exhaustively explored in the field of drug design and development. Continuous efforts are being carried out for the development of medicinal agents especially, for dreadful diseases like cancer. Thiophene, a sulfur containing heterocyclic scaffold, has emerged as one of the relatively well-explored scaffold for the development of library of molecules having potential anticancer profile. Thiophene analogs have been reported to bind with a wide range of cancer-specific protein targets, depending on the nature and position of substitutions. Accordingly, thiophene analogs have been reported to cause their biological action through inhibition of different signaling pathways involved in cancer. Functionally, different anticancer targets require different structural features, so researchers have tried to synthesize new thiophene derivatives with varied substitutions. In the present review, authors have presented the information available on thiophene-based molecules as anticancer agents with special focus on synthetic methodologies, biological profile and structure activity relationship (SAR) studies. Various patents granted for thiophene containing molecules as anticancer have also been included.

Design, synthesis, chemical characterization, biological evaluation, and docking study of new 1,3,4-oxadiazole homonucleoside analogs

Herein, we report the synthetic strategies and characterization of some novel 1,3,4-oxadiazole homonucleoside analogs that are relevant to potential antitumor and cytotoxic activities. The structure of all compounds is confirmed using various spectroscopic methods such as ¹H-NMR, ¹³C-NMR, HRMS, and FTIR. These compounds were evaluated against three human cancer cell lines (MCF-7, SKBR3, and HL60 Cell Line). Preliminary investigations showed that the cytotoxic activity was markedly dependent on the nucleobase. Introduction of 5-Iodouracil 4g and theobromine 6b proved to be extremely beneficial even they were more potent than the reference drug (DOX). Also, the synthesized compounds were tested for their antiviral activities against the human varicella-zoster virus (VZV). The product 4h was (6-azauracil derivative) more potent to the reference (acyclovir) against the deficient TK - VZV strain by about 2-fold. Finally, molecular docking suggested that the anticancer activities of compounds 6b and 4g mediated by inhibiting dual proteins EGFR/HER2 with low micromolar inhibition constant Ki range. The 1,3,4-oxadiazole homonucleosides showed a strong affinity to binding sites of target proteins by forming H-bond, carbon-hydrogen bond, Pi-anion, Pi-sulfur, Pi-sigma, alkyl, and Pi-alkyl interactions.

Structure-based design generated novel hydroxamic acid based preferential HDAC6 lead inhibitor with on-target cytotoxic activity against primary choroid plexus carcinoma

Histone deacetylase 6 (HDAC6) is an attractive target for cancer therapeutic intervention. Selective HDAC6 inhibitors is important to minimise the side effects of pan inhibition. Thus, new class of hydroxamic acid-based derivatives were designed on structural basis to perform preferential activity against HDAC6 targeting solid tumours. Interestingly, 1-benzylbenzimidazole-2-thio-N-hydroxybutanamide 10a showed impressive preference with submicromolar potency against HDAC6 (IC₅₀ = 510 nM). 10a showed cytotoxic activity with interesting profile against CCHE-45 at (IC₅₀ = 112.76 µM) when compared to standard inhibitor Tubacin (IC₅₀ = 20 µM). Western blot analysis of acetylated-α-tubulin verified the HDAC6 inhibiting activity of 10a. Moreover, the insignificant difference in acetylated-α-tubulin induced by 10a and Tubacin implied the on-target cytotoxic activity of 10a. Docking of 10a in the binding site of HDAC6 attributed the activity of 10a to π-π stacking with the amino acids of the hydrophobic channel of HDAC6 and capture of zinc metal in bidentate fashion. The therapeutic usefulness besides the on-target activity may define 10a as an interesting safe-lead inhibitor for future development.

Design, synthesis and anticancer evaluation of thieno[2,3-d]pyrimidine derivatives as dual EGFR/HER2 inhibitors and apoptosis inducers

Deregulation of many kinases is directly linked to cancer development and the tyrosine kinase family is one of the most important targets in current cancer therapy regimens. In this study, we have designed and synthesized a series of thieno[2,3-d]pyrimidine derivatives as an EGFR and HER2 tyrosine kinase inhibitors. All the synthesized compounds were evaluated in vitro for their inhibitory activities against EGFR^WT; and the most active compounds that showed promising IC₅₀ values against EGFR^WT were tested in vitro for their inhibitory activities against mutant EGFR^T790M and HER2 kinases. Moreover, the antitumor activities of these compounds were tested against four cancer cell lines (HepG2, HCT-116, MCF-7 and A431). Compounds 13g, 13h and 13k exhibited the highest activities against the examined cell lines with IC₅₀ values ranging from 7.592 ± 0.32 to 16.006 ± 0.58 µM comparable to that of erlotinib (IC₅₀ ranging from 4.99 ± 0.09 to 13.914 ± 0.36 µM). Furthermore, the most potent antitumor agent (13k) was selected for further studies to determine its effect on the cell cycle progression and apoptosis in MCF-7 cell line. The results indicated that this compound arrests G₂/M phase of the cell cycle and it is a good apoptotic agent. Finally, molecular docking studies showed a good binding pattern of the synthesized compounds with the prospective target, EGFR^WT and EGFR^T790M.

Design, Synthesis, and Biological Evaluation of 6-Substituted Thieno[3,2- d]pyrimidine Analogues as Dual Epidermal Growth Factor Receptor Kinase and Microtubule Inhibitors

The clinical evidence for the success of tyrosine kinase inhibitors in combination with microtubule-targeting agents prompted us to design and develop single agents that possess both epidermal growth factor receptor (EGFR) kinase and tubulin polymerization inhibitory properties. A series of 6-aryl/heteroaryl-4-(3',4',5'-trimethoxyanilino)thieno[3,2- d]pyrimidine derivatives were discovered as novel dual tubulin polymerization and EGFR kinase inhibitors. The 4-(3',4',5'-trimethoxyanilino)-6-( p-tolyl)thieno[3,2- d]pyrimidine derivative 6g was the most potent compound of the series as an antiproliferative agent, with half-maximal inhibitory concentration (IC₅₀) values in the single- or double-digit nanomolar range. Compound 6g bound to tubulin in the colchicine site and inhibited tubulin assembly with an IC₅₀ value of 0.71 μM, and 6g inhibited EGFR activity with an IC₅₀ value of 30 nM. Our data suggested that the excellent in vitro and in vivo profile of 6g may be derived from its dual inhibition of tubulin polymerization and EGFR kinase.