Targeting EGFR/HER2 tyrosine kinases with a new potent series of 6-substituted 4-anilinoquinazoline hybrids: Design, synthesis, kinase assay, cell-based assay, and molecular docking

Synthesis of novel pyrimido[4,5-b]quinoline derivatives as dual EGFR/HER2 inhibitors as anticancer agents

A series of novel N-aryl-5-aryl-6,7,8,9-tetrahydropyrimido[4,5-b]quinolin-4-amines 4a-4l was synthesized as potential anticancer agents through Dimroth rearrangement reaction of intermediates 3a-3c. Pyrimido[4,5-b]quinolines 4a-4l showed promising activity against the Michigan Cancer Foundation-7 (MCF-7) cell line, compared with lapatinib as the reference drug. Compounds 4d, 4h, 4i, and 4l demonstrated higher cytotoxic activity than lapatinib, with IC50 values of 2.67, 6.82, 4.31, and 1.62 µM, respectively. Compounds 4d, 4i, and 4l showed promising epidermal growth factor receptor (EGFR) inhibition with IC50 values of 0.065, 0.116, and 0.052 µM, respectively. These compounds were subjected to human epidermal growth factor receptor 2 (HER2) inhibition and showed IC50 values of 0.09, 0.164, and 0.055 µM, respectively. Compounds 4d, 4i, and 4l are good candidates as dual EGFR/HER2 inhibitors. The most active compound, 4l, was subjected to cell-cycle analysis and induced cell-cycle arrest at the S phase. Compound 4l induced apoptosis 60-fold compared with control untreated MCF-7 cells. 4l can inhibit cancer metastasis. It reduced MCF-7 cell infiltration and metastasis by 45% compared with control untreated cells.

Development of new TAK-285 derivatives as potent EGFR/HER2 inhibitors possessing antiproliferative effects against 22RV1 and PC3 prostate carcinoma cell lines

Epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) protein tyrosine kinases co-expressed in various cancers such as ovarian, breast, colon, and prostate subtypes. Herein, new TAK-285 derivatives (9a-h) were synthesised, characterised, and biologically evaluated as dual EGFR/HER2 inhibitors. Compound 9f exhibited IC₅₀ values of 2.3 nM over EGFR and 234 nM over HER2, which is 38-fold of staurosporine and 10-fold of TAK-285 over EGFR. Compound 9f also showed high selectivity profile when tested over a small kinase panel. Compounds 9a-h showed IC₅₀ values in the range of 1.0-7.3 nM and 0.8-2.8 nM against PC3 and 22RV1 prostate carcinoma cell lines, respectively. Cell cycle analysis, apoptotic induction, molecular docking, dynamics, and MM-GBSA studies confirmed the plausible mechanism(s) of compound 9f as a potent EGFR/HER2 dual inhibitor with an effective antiproliferative action against prostate carcinoma.

Machine Learning-Based Approach to Developing Potent EGFR Inhibitors for Breast Cancer-Design, Synthesis, and In Vitro Evaluation

The epidermal growth factor receptor (EGFR) is vital for regulating cellular functions, including cell division, migration, survival, apoptosis, angiogenesis, and cancer. EGFR overexpression is an ideal target for anticancer drug development as it is absent from normal tissues, marking it as tumor-specific. Unfortunately, the development of medication resistance limits the therapeutic efficacy of the currently approved EGFR inhibitors, indicating the need for further development. Herein, a machine learning-based application that predicts the bioactivity of novel EGFR inhibitors is presented. Clustering of the EGFR small-molecule inhibitor (∼9000 compounds) library showed that N-substituted quinazolin-4-amine-based compounds made up the largest cluster of EGFR inhibitors (∼2500 compounds). Taking advantage of this finding, rational drug design was used to design a novel series of 4-anilinoquinazoline-based EGFR inhibitors, which were first tested by the developed artificial intelligence application, and only the compounds which were predicted to be active were then chosen to be synthesized. This led to the synthesis of 18 novel compounds, which were subsequently evaluated for cytotoxicity and EGFR inhibitory activity. Among the tested compounds, compound 9 demonstrated the most potent antiproliferative activity, with 2.50 and 1.96 μM activity over MCF-7 and MDA-MB-231 cancer cell lines, respectively. Moreover, compound 9 displayed an EGFR inhibitory activity of 2.53 nM and promising apoptotic results, marking it a potential candidate for breast cancer therapy.

Sulfonylated Indeno[1,2-c]quinoline Derivatives as Potent EGFR Tyrosine Kinase Inhibitors

The epidermal growth factor receptor (EGFR) has been considered a potential target for lung cancer therapy due to its essential role in regulating the survival and proliferation of cancer cells. Although erlotinib, a potent EGFR tyrosine kinase (EGFR-TK) inhibitor, has been used as the first-line drug for lung cancer treatment, acquired drug resistance caused by the T790M secondary mutation of EGFR-TK inevitably develops after a median response duration of 9-13 months. Thus, the search for promising compounds to effectively target EGFR-TK has become an imperative necessity. In this study, the kinase inhibitory activities of a series of sulfonylated indeno[1,2-c]quinolines (SIQs) against EGFR-TK were experimentally and theoretically investigated. Among the 23 SIQ derivatives studied, eight compounds showed enhanced EGFR-TK inhibitory activity (IC₅₀ values of ca. 0.6-10.2 nM) compared to the known drug erlotinib (IC₅₀ of ∼20 nM). In a cell-based assay in human cancer cell lines with EGFR overexpression (A549 and A431 cells), the eight selected SIQs all showed more significant cytotoxicity against A431 than A549 cells, consistent with the higher EGFR expression in A431 cells. Molecular docking and FMO-RIMP2/PCM calculations revealed that SIQ17 occupies the ATP-binding site of EGFR-TK, where its sulfonyl group is mainly stabilized by C797, L718, and E762 residues. Triplicate 500 ns molecular dynamics (MD) simulations also confirmed the binding strength of SIQ17 in complex with EGFR. Overall, the potent SIQ compounds obtained in this work could be further optimized for developing novel anticancer drug candidates targeting EGFR-TK.

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.

Design, Synthesis, Biological Evaluation, and Molecular Dynamics Studies of Novel Lapatinib Derivatives

Co-expression of the epidermal growth factor receptor (EGFR, also known as ErbB1) and human epidermal growth factor receptor 2 (HER2) has been identified as a diagnostic or prognostic sign in various tumors. Despite the fact that lapatinib (EGFR/HER2 dual inhibitor) has shown to be successful, many patients do not respond to it or develop resistance for a variety of reasons that are still unclear. As a result, new approaches and inhibitory small molecules are still needed for EGFR/HER2 inhibition. Herein, novel lapatinib derivatives possessing 4-anilinoquinazoline and imidazole scaffolds (6a-l) were developed and screened as EGFR/HER2 dual inhibitors. In vitro and in silico investigations revealed that compound 6j has a high affinity for the ATP-binding regions of EGFR and HER2. All of the designed candidates were predicted to not penetrate the BBB, raising the expectation for the absence of CNS side effects. At 10 µM, derivatives possessing 3-chloro-4-(pyridin-2-ylmethoxy)aniline moiety (6i-l) demonstrated outstanding ranges of percentage inhibition against EGFR (97.65-99.03%) and HER2 (87.16-96.73%). Compound 6j showed nanomolar IC₅₀ values over both kinases (1.8 nM over EGFR and 87.8 nM over HER2). Over EGFR, compound 6j was found to be 50-fold more potent than staurosporine and 6-fold more potent than lapatinib. A kinase selectivity panel of compound 6j showed poor to weak inhibitory activity over CDK2/cyclin A, c-MET, FGFR1, KDR/VEGFR2, and P38a/MAPK14, respectively. Structure-activity relationship (SAR) that were obtained with different substitutions were justified. Additionally, molecular docking and molecular dynamics studies revealed insights into the binding mode of the target compounds. Thus, compound 6j was identified as a highly effective and dual EGFR/HER2 inhibitor worthy of further investigation.

Structural insights into conformational stability and binding of thiazolo-[2,3-b] quinazolinone derivatives with EGFR-TKD and in-vitro study

Heterocyclic molecules are well-known drugs against various diseases including cancer. Many tyrosine kinase inhibitors including erlotinib, osimertinib, and sunitinib were developed and approved but caused adverse effects among treated patients. Which prevents them from being used as cancer therapeutics. In this study, we strategically developed heterocyclic thiazolo-[2,3-b]quinazolinone derivatives by an organic synthesis approach. These synthesized molecules were assessed against the epidermal growth factor receptor tyrosine kinase domain (EGFR-TKD) by in silico methods. Molecular docking simulations unravel derivative 17 showed better binding energy scores and followed Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties. The binding affinity displayed by synthetic congener and reference molecule erlotinib was found to be -8.26 ± 0.0033 kcal/mol and -7.54 ± 0.1411 kcal/mol with the kinase domain. Further, molecular dynamic simulations were conducted thrice to validate the molecular docking study and achieved significant results. Both synthetic derivative and reference molecule attained stability in the active site of the TKD. The synthetic congener and erlotinib showed free energy binding (ΔGbind) -102.975 ± 3.714 kJ/mol and -130.378 ± 0.355 kJ/mol computed by Molecular Mechanics Poison Boltzmann Surface Area (MM-PBSA) method. In addition, the motions of each sampled system including the Apo complex were determined by the principal component analysis and Gibbs energy landscape analysis. The in-vitro apoptosis study was performed using MCF-7 and H-1299 cancer cell lines. However, thiazolo-[2,3-]-quinazoline derivative 17 showed fair anti-proliferative activity against MCF-7 and H-1299. Further, the in-vivo study is necessary to determine the effectivity of the potent anti-proliferative, non-toxic molecule against TKD.

Design, synthesis, and biological evaluation of pseudo-bicyclic pyrimidine-based compounds as potential EGFR inhibitors

Cancer is one of the most dangerous diseases harvesting millions of lives every year globally, which mandates the development of new therapies. In this report, we designed and synthesized a novel series of compounds based on the structure of lapatinib and AF8c, a compound we developed and reported previously, to target EGFR kinase. The series was assayed against a panel of 60 cancer cell lines at the National Cancer Institute (NCI). Compounds 4a, 4f, 4 g, and 4 l showed high efficacy against melanoma, colon, and blood cancers, with 4a being the most effective. The evaluation of the potency of 4a against the 60 cell lines in a five-dose assay revealed a significant potency compared to lapatinib against melanoma, colon, and blood cancers. In vitro enzyme assay over 30 kinases showed significant potency against EGFR and high selectivity to EGFR among the tested kinases. A molecular modeling study of 4a and lapatinib inside the pockets of EGFR revealed that both compounds bind strongly inside the ATP-binding pocket of the EGFR kinase domain. Therefore, we present 4a as a novel EGFR kinase inhibitor with potent in vitro cellular activity against diverse types of cancer cells.

AF8c, a Multi-Kinase Inhibitor Induces Apoptosis by Activating DR5/Nrf2 via ROS in Colorectal Cancer Cells

Simple Summary

AF8c, a lapatinib hybrid quinazoline-based EGFR/HER2 inhibitor, was chosen to scrutinize its antiproliferative activity in colorectal cancer (CRC) cells. We found that AF8cinduced apoptosis in CRC cells via diverse mechanisms. In addition to inhibiting the phosphorylation of the ErbB family, AF8c increased the mRNA and protein levels of death receptor 5 (DR5) in vitro and in vivo. In addition, AF8c upregulated several ER stress proteins and the redox-sensitive nuclear respiratory factor 2 alpha subunit (Nrf2) in a p53-dependent manner. We also found that the AF8c-induced increase in the levels of Nrf2, DR5, and apoptosis was diminished by p53 downregulation or knockdown. Furthermore, AF8c showed higher antiproliferative activity than lapatinib in the CRC mouse model in vivo. Therefore, our results suggest AF8c as a highly effective polypharmacological small molecule with an encouraging safety profile, both in vitro and in vivo, for further evaluation as a treatment of CRC.

Abstract

Our team has previously reported a series of quinazoline-based lapatinib hybrids as potent kinase-targeting anticancer agents. Among them, AF8c showed a relatively safe profile in colorectal cancer (CRC) cells. In this study, we delineate a novel anticancer activity of AF8c in CRC cells. AF8c mediated p53-dependent apoptosis of CRC cells via the generation of endoplasmic reticulum (ER) stress and reactive oxygen species (ROS), as well as activation of nuclear respiratory factor 2 alpha subunit (Nrf2) and death receptor 5 (DR5), among others. The silencing of DR5 attenuated the expression levels of Nrf2 and partially inhibited AF8c-induced apoptosis. Additionally, upregulation of Nrf2 by AF8c evoked apoptosis through a decrease in antioxidant levels. Treatment of a CRC mice model with AF8c also resulted in the upregulation of DR5, Nrf2, and CHOP proteins, subsequently leading to a significant decrease in tumor burden. In comparison with lapatinib, AF8c showed higher cellular antiproliferative activity at the tested concentrations in CRC cells and synergized TRAIL effects in CRC cells. Overall, our results suggest that AF8c-induced apoptosis may be associated with DR5/Nrf2 activation through ER stress and ROS generation in CRC cells. These findings indicate that AF8c represents a promising polypharmacological molecule for the treatment of human CRC.

4-Anilinoquinazoline-based benzenesulfonamides as nanomolar inhibitors of carbonic anhydrase isoforms I, II, IX, and XII: design, synthesis, in-vitro, and in-silico biological studies

Human carbonic anhydrase inhibitors (hCAIs) are a key therapeutic class with a multitude of novel applications such as anticonvulsants, topically acting antiglaucoma, and anticancer drugs. Herein, a new series of 4-anilinoquinazoline-based benzenesulfonamides were designed, synthesised, and biologically assessed as potential hCAIs. The target compounds are based on the well-tolerated kinase scaffold (4-anilinoquinazoline). Compounds 3a (89.4 nM), 4e (91.2 nM), and 4f (60.9 nM) exhibited 2.8, 2.7, and 4 folds higher potency against hCA I when compared to the standard (AAZ, V), respectively. A single digit nanomolar activity was elicited by compounds 3a (8.7 nM), 4a (2.4 nM), and 4e (4.6 nM) with 1.4, 5, and 2.6 folds of potency compared to AAZ (12.1 nM) against isoform hCA II, respectively. Structure-activity relationship (SAR) and molecular docking studies validated our design approach that revealed highly potent hCAIs.

Discovery of a Series of 1,2,3-Triazole-Containing Erlotinib Derivatives With Potent Anti-Tumor Activities Against Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are emerging at the vanguard of therapy for non-small-cell lung cancer (NSCLC) patients with EGFR-activating mutations. However, the increasing therapeutic resistance caused by novel mutations or activated bypass pathways has impaired their performance. In this study, we link one of the commercial EGFR-TKIs, Erlotinib, to different azide compounds to synthesize a novel class of 1,2,3-triazole ring-containing Erlotinib derivatives. We discovered that several new compounds show robust antiproliferation activity against diverse NSCLC cells in vitro including PC-9, H460, H1975 and A549. Two of the most potent compounds, e4 and e12 have been found to be more efficient than Erlotinib in all NSCLC cell lines except PC-9. They significantly induce apoptosis and cell cycle arrest in PC-9 and H460 cells. The antitumor efficacy of compound e4 in vivo is close to that of Erlotinib in a PC-9 xenograft mouse model. Most Erlotinib-1,2,3-triazole compounds exhibit moderate to good inhibitory activities toward wild-type EGFR as indicated by enzyme-linked immunosorbent assay (ELISA), and the EGFR phosphorylation was inhibited in H460 and PC-9 cells exposed to e4 or e12. These data suggest that these Erlotinib-1,2,3-triazole compounds are suitable candidates for use against NSCLC and more unknown mechanisms merit further investigation.

Hit Identification of a Novel Quinazoline Sulfonamide as a Promising EphB3 Inhibitor: Design, Virtual Combinatorial Library, Synthesis, Biological Evaluation, and Docking Simulation Studies

EphB3 is a major key player in a variety of cellular activities, including cell migration, proliferation, and apoptosis. However, the exact role of EphB3 in cancer remains ambiguous. Accordingly, new EphB3 inhibitors can increase the understanding of the exact roles of the receptor and may act as promising therapeutic candidates. Herein, a hybrid approach of structure-based design and virtual combinatorial library generated 34 quinazoline sulfonamides as potential selective EphB3 inhibitors. A molecular docking study over EphB3 predicted the binding affinities of the generated library, and the top seven hit compounds (3a and 4a–f), with GlideScore ≥ −6.20 Kcal/mol, were chosen for further MM-GBSA calculations. Out of the seven top hits, compound 4c showed the highest MM-GBSA binding free energy (−74.13 Kcal/mol). To validate these predicted results, compounds 3a and 4a–f were synthesized and characterized using NMR, HRMS, and HPLC. The biological evaluation revealed compound 4c as a potent EphB3 inhibitory lead (IC₅₀ = 1.04 µM). The screening of 4c over a mini-panel of kinases consisting of EGFR, Aurora A, Aurora B, CDK2/cyclin A, EphB1, EphB2, EphB4, ERBB2/HER2, and KDR/VEGFR2, showed a promising selective profile against EphB3 isoform. A dose-dependent assay of compound 4c and a molecular docking study over the different forms of EphB provided insights into the elicited biological activities and highlighted reasonable explanations of the selectivity.

Scaffold Repurposing of In-House Small Molecule Candidates Leads to Discovery of First-in-Class CDK-1/HER-2 Dual Inhibitors: In Vitro and In Silico Screening

Recently, multitargeted drugs are considered a potential approach in treating cancer. In this study, twelve in-house indole-based derivatives were preliminary evaluated for their inhibitory activities over VEGFR-2, CDK-1/cyclin B and HER-2. Compound 15l showed the most inhibitory activities among the tested derivatives over CDK-1/cyclin B and HER-2. Compound 15l was tested for its selectivity in a small kinase panel. It showed dual selectivity for CDK-1/cyclin B and HER-2. Moreover, in vitro cytotoxicity assay was assessed for the selected series against nine NCI cell lines. Compound 15l showed the most potent inhibitory activities among the tested compounds. A deep in silico molecular docking study was conducted for compound 15l to identify the possible binding modes into CDK-1/cyclin B and HER-2. The docking results revealed that compound 15l displayed interesting binding modes with the key amino acids in the binding sites of both kinases. In vitro and in silico studies demonstrate the indole-based derivative 15l as a selective dual CDK-1 and HER-2 inhibitor. This emphasizes a new challenge in drug development strategies and signals a significant milestone for further structural and molecular optimization of these indole-based derivatives in order to achieve a drug-like property.

Development of New Meridianin/Leucettine-Derived Hybrid Small Molecules as Nanomolar Multi-Kinase Inhibitors with Antitumor Activity

Although the sea ecosystem offers a broad range of bioactivities including anticancer, none of the FDA-approved antiproliferative protein kinase inhibitors are derived from a marine source. In a step to develop new marine-inspired potent kinase inhibitors with antiproliferative activities, a new series of hybrid small molecules (5a–5g) was designed and synthesized based on chemical moieties derived from two marine natural products (Meridianin E and Leucettamine B). Over a panel of 14 cancer-related kinases, a single dose of 10 µM of the parent hybrid 5a possessing the benzo[d][1,3]dioxole moiety of Leucettamine B was able to inhibit the activity of FMS, LCK, LYN, and DAPK1 kinases with 82.5 ± 0.6, 81.4 ± 0.6, 75.2 ± 0.0, and 55 ± 1.1%, respectively. Further optimization revealed the most potent multiple kinase inhibitor of this new series (5g) with IC₅₀ values of 110, 87.7, and 169 nM against FMS, LCK, and LYN kinases, respectively. Compared to imatinib (FDA-approved multiple kinase inhibitor), compound 5g was found to be ~ 9- and 2-fold more potent than imatinib over both FMS and LCK kinases, respectively. In silico docking simulation models of the synthesized compounds within the active site of FMS, LCK, LYN, and DAPK1 kinases offered reasonable explanations of the elicited biological activities. In an in vitro anticancer assay using a library of 60 cancer cell lines that include blood, lung, colon, CNS, skin, ovarian, renal, prostate, and breast cancers, it was found that compound 5g was able to suppress 60 and 70% of tumor growth in leukemia SR and renal RXF 393 cell lines, respectively. Moreover, an ADME study indicated a suitable profile of compound 5g concerning cell permeability and blood-brain barrier (BBB) impermeability, avoiding possible CNS side effects. Accordingly, compound 5g is reported as a potential lead towards novel antiproliferative marine-derived kinase modulators.

New horizons in drug discovery of lymphocyte-specific protein tyrosine kinase (Lck) inhibitors: a decade review (2011-2021) focussing on structure-activity relationship (SAR) and docking insights

Lymphocyte-specific protein tyrosine kinase (Lck), a non-receptor Src family kinase, has a vital role in various cellular processes such as cell cycle control, cell adhesion, motility, proliferation, and differentiation. Lck is reported as a key factor regulating the functions of T-cell including the initiation of TCR signalling, T-cell development, in addition to T-cell homeostasis. Alteration in expression and activity of Lck results in numerous disorders such as cancer, asthma, diabetes, rheumatoid arthritis, atherosclerosis, and neuronal diseases. Accordingly, Lck has emerged as a novel target against different diseases. Herein, we amass the research efforts in literature and pharmaceutical patents during the last decade to develop new Lck inhibitors. Additionally, structure-activity relationship studies (SAR) and docking models of these new inhibitors within the active site of Lck were demonstrated offering deep insights into their different binding modes in a step towards the identification of more potent, selective, and safe Lck inhibitors.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

The Journey of DDR1 and DDR2 Kinase Inhibitors as Rising Stars in the Fight Against Cancer

Discoidin domain receptor (DDR) is a collagen-activated receptor tyrosine kinase that plays critical roles in regulating essential cellular processes such as morphogenesis, differentiation, proliferation, adhesion, migration, invasion, and matrix remodeling. As a result, DDR dysregulation has been attributed to a variety of human cancer disorders, for instance, non-small-cell lung carcinoma (NSCLC), ovarian cancer, glioblastoma, and breast cancer, in addition to some inflammatory and neurodegenerative disorders. Since the target identification in the early 1990s to date, a lot of efforts have been devoted to the development of DDR inhibitors. From a medicinal chemistry perspective, we attempted to reveal the progress in the development of the most promising DDR1 and DDR2 small molecule inhibitors covering their design approaches, structure-activity relationship (SAR), biological activity, and selectivity.

Systematic insight into the active constituents and mechanism of Guiqi Baizhu for the treatment of gastric cancer

Traditional Chinese medicine treatment of diseases has been recognized, but the material basis and mechanisms are not clear. In this study, target prediction of the antigastric cancer (GC) effect of Guiqi Baizhu (GQBZP) and the analysis of potential key compounds, key targets, and key pathways for the therapeutic effects against GC were carried out based on the method of network analysis and Kyoto Encyclopedia of Genes and Genomes enrichment. There were 33 proteins shared between GQBZP and GC, and 131 compounds of GQBZP had a high correlation with these proteins, indicating that the PI3K‐AKT signaling pathway might play a key role in GC. From these studies, we selected human epidermal growth factor receptor 2 (HER2) and programmed cell death 1‐ligand 1 (PD‐L1) for docking; the results showed that 385 and 189 compounds had high docking scores with HER2 and PD‐L1, respectively. Six compounds were selected for microscale thermophoresis (MST). Daidzein/quercetin and isorhamnetin/formononetin had the highest binding affinity for HER2 and PD‐L1, with K_d values of 3.7 μmol/L and 490, 667, and 355 nmol/L, respectively. Molecular dynamics simulation studies based on the docking complex structures as the initial conformation yielded the binding free energy between daidzein/quercetin with HER2 and isorhamnetin/formononetin with PD‐L1, calculated by molecular mechanics Poisson‐Boltzmann surface area, of −26.55, −14.18, −19.41, and −11.86 kcal/mol, respectively, and were consistent with the MST results. In vitro experiments showed that quercetin, daidzein, and isorhamnetin had potential antiproliferative effects in MKN‐45 cells. Enzyme activity assays showed that quercetin could inhibit the activity of HER2 with an IC₅₀ of 570.07 nmol/L. Our study provides a systematic investigation to explain the material basis and molecular mechanism of traditional Chinese medicine in treating diseases.

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).

Molecular docking analysis of HER-2 inhibitor from the ZINC database as anticancer agents

The human epidermal growth factor (HER2) is a transmembrane receptor that is highly expressed in breast cancer and in different other cancers. Therefore, it is of interest to identify the new HER2 inhibitors from a selected 300 compounds in the ZINC database. The top two hit compounds (ZINC000014780728 (-11.0 kcal/mol) and ZINC000014762512 (-10.8 kcal/mol)) showed a high affinity with HER2 relative to the reference compound (lapatinib (-10.2 kcal/mol)) for further consideration.

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.

Novel quinazoline-based EGFR kinase inhibitors: A review focussing on SAR and molecular docking studies (2015-2019)

The over expression of EGFR has been recognized as the driver mechanism in the occurrence and progression of carcinomas such as lung cancer, breast cancer, pancreatic cancer, etcetera. EGFR receptor was thus established as an important target for the management of solid tumors. The occurrence of resistance caused as a result of mutations in EGFR has presented a formidable challenge in the discovery of novel inhibitors of EGFR. This has resulted in the development of three generations of EGFR TKIs. Newer mutations like C797S cause failure of Osimertinib and other EGFR TKIs belonging to the third-generation caused by the development of resistance. In this review, we have summarized the work done in the last five years to overcome the limitations of currently marketed drugs, giving structural activity relationships of quinazoline-based lead compounds synthesized and tested recently. We have also highlighted the shortcomings of the currently used approaches and have provided guidance for circumventing these limitations. Our review would help medicinal chemists streamline and guide their efforts towards developing novel quinazoline-based EGFR inhibitors.

In vivo efficacy studies of novel quinazoline derivatives as irreversible dual EGFR/HER2 inhibitors, in lung cancer xenografts (NCI-H1975) mice models

Lung cancer is the most common cancer and leading cause of cancer-related deaths worldwide. The first-generation reversible, ATP-competitive inhibitors gefetinib and elotinib showed good clinical responses in lung adenocarcinoma tumors (NSCLC). But almost all patients developed resistance to these inhibitors over time. Such resistance of EGFR inhibitors was frequently linked to the acquired L858R and T790M point mutations in the kinase domain of EGFR. To overcome these resistance problems, the second and the third generation inhibitors have been discovered. FDA approved afatinib, the second generation irreversible inhibitor and osimitinib, the third generation irreversible EGFR inhibitors for the treatments of NSCLC. We identified new covalent quinazoline inhibitors (E)-N-(4-(3-chloro-4-fluorophenylamino)-7-(2-ethoxyethoxy)quinazolin-6-yl)-4-(dimethylamino)but-2-enamide (6d) and (E)-N-(4-(3-chloro-4-(pyridin-2-ylmethoxy)phenylamino)-7-(2-ethoxyethoxy)quinazolin-6-yl)-4-(dimethyl-amino)but-2-enamide (6h) that exhibited potent EGFR kinase inhibitory activities on L858R and T790M mutations. The compound 6 h showed selectivity similar to AZD9291 (osimertinib) in mutated and wild type tumor cell lines. In vitro cell assay 6d and 6h were better than afatinib and osimertinib. In vivo antitumor efficacy studies of these compounds were done in NCI-H1975 mice xenografts.

Exploring structural features of EGFR-HER2 dual inhibitors as anti-cancer agents using G-QSAR approach

Simultaneous inhibition of EGFR and HER2 by dual-targeting inhibitors is an established anti-cancer strategy. Therefore, a recent trend in drug discovery involves understanding the features of such dual inhibitors. In this study, three different G-QSAR models were developed corresponding to individual EGFR, HER2 and the dual-model for both receptors. The dual-model provided site-specific information wherein (i) increasing electronegative character and higher index of saturated carbon at R4 position; (ii) presence of chlorine atom at R2 position; (iii) decreasing alpha modified shape index at R1 and R3 positions; and (iv) less electronegativity at R2 position; were found important for enhancing the dual activity. Also, comparison of dual-model with the EGFR/HER2 individual models revealed that it incorporates the properties of both models and, thus, represents a combination of EGFR/HER2. Further, fragment analysis revealed that R2 and R4 are important for imparting high potency while specificity is decided by R1/R3 fragment. We also checked the predictive ability of the dual-model by determining applicability domain using William's plot. Also, analysis of active molecules showed they show favorable substitutions that agree with the constructed dual-model. Thus, we have been successful in developing a single dual-response QSAR model to get an insight into various structural features influencing EGFR/HER2 activity.

Novel sulphonamide benzoquinazolinones as dual EGFR/HER2 inhibitors, apoptosis inducers and radiosensitizers

A series of sulphonamide benzoquinazolinones 5-18 was synthesized and evaluated for cytotoxic activity against MDA-MB-231 cell line. The compounds showed IC₅₀ ranging from 0.26 to 161.49 µM. The promising compounds were evaluated for their inhibitory profile against epidermal growth factor (EGFR) and HER2 enzymes. Compound 10 showed more potent activity on both EGFR and HER2 than erlotinib (IC₅₀ 3.90 and 5.40 µM versus 6.21 and 9.42 µM). The pro-apoptotic activity of 10 was evaluated against caspase-3, Bax, B-cell lymphoma protein 2 (Bcl-2) expression levels, and cell cycle analysis. Compound 10 increased the level of caspase-3 by 10 folds, Bax level by 9 folds, decreased the level of the Bcl-2 by 0.14 and arrested the cell cycle in the G2/M phase. The radio-sensitizing activity of 10 was measured using a single dose of 8 Gy gamma radiation (IC₅₀ decreased from 0.31 to 0.22 µM). Molecular docking was performed on EGFR and HER2 receptors.

First-in-class DAPK1/CSF1R dual inhibitors: Discovery of 3,5-dimethoxy-N-(4-(4-methoxyphenoxy)-2-((6-morpholinopyridin-3-yl)amino)pyrimidin-5-yl)benzamide as a potential anti-tauopathies agent

Kinase irregularity has been correlated with several complex neurodegenerative tauopathies. Development of selective inhibitors of these kinases might afford promising anti-tauopathy therapies. While DAPK1 inhibitors halt the formation of tau aggregates and counteract neuronal death, CSF1R inhibitors could alleviate the tauopathies-associated neuroinflammation. Herein, we report the design, synthesis, biological evaluation, mechanistic study, and molecular docking study of novel CSF1R/DAPK1 dual inhibitors as multifunctional molecules inhibiting the formation of tau aggregates and neuroinflammation. Compound 3l, the most potent DAPK1 inhibitor in the in vitro kinase assay (IC₅₀ = 1.25 μM) was the most effective tau aggregates formation inhibitor in the cellular assay (IC₅₀ = 5.0 μM). Also, compound 3l elicited potent inhibition of CSF1R in the in vitro kinase assay (IC₅₀ = 0.15 μM) and promising inhibition of nitric oxide production in LPS-induced BV-2 cells (55% inhibition at 10 μM concentration). Kinase profiling and hERG binding assay anticipated the absence of off-target toxicities while the PAMPA-BBB assay predicted potentially high BBB permeability. The mechanistic study and selectivity profile suggest compound 3l as a non-ATP-competitive DAPK1 inhibitor and an ATP-competitive CSF1R inhibitor while the in silico calculations illustrated binding of compound 3l to the substrate-binding site of DAPK1. Hence, compound 3l might act as a protein-protein interaction inhibitor by hindering DAPK1 kinase reaction through preventing the binding of DAPK1 substrates.

Allenamide as a bioisostere of acrylamide in the design and synthesis of targeted covalent inhibitors

The success of acrylamide-containing drugs in treating cancers has spurred a passion to search for acrylamide bioisosteres. In our endeavour, we have identified that an allenamide group can be a reactive bioisostere of the acrylamide group. In our development of allenamide-containing compounds, we found that the most potent compound, 14, inhibited the kinase activities of both T790M/L858R double mutant and wild type EGFR in a low nM range. 14 also inhibited the growth of NCI-H1975 lung cancer cells at IC₅₀ = 33 nM, which is comparable to that of acrylamide-containing osimertinib. The western blot analysis showed that the phosphorylation of EGFR, AKT, and ERK1/2 was simultaneously inhibited in a dose-dependent manner when NCI-H1975 cells were treated with 14. By measuring the conjugate addition product formed by 14 and GSH, we obtained a reaction rate constant of 302.5 × 10^-3 min^-1, which is about 30-fold higher than that of osimertinib. Taken together, our data suggest that the allenamide-containing compounds inhibited EGFR kinases through covalent modifications. Our study indicates that the allenamide group could serve as an alternative electrophilic warhead in the design of targeted covalent inhibitors, and this bioisostere replacement may have broad applications in medicinal chemistry.

Benzo[g]quinazolin-based scaffold derivatives as dual EGFR/HER2 inhibitors

Targeting EGFR has proven to be beneficial in the treatment of several types of solid tumours. So, a series of novel 2-(4-oxo-3-(4-sulfamoylphenyl)-3,4-dihydrobenzo[g]quinazolin-2-ylthio)-N-substituted acetamide 5–19 were synthesised from the starting material 4-(2-mercapto-4-oxobenzo[g]quinazolin-3(4H)-yl) benzenesulfonamide 4, to be evaluated as dual EGFR/HER2 inhibitors. The target compounds 5–19, were screened for their cytotoxic activity against A549 lung cancer cell line. The percentage inhibition of EGFR enzyme was measured and compared with erlotinib as the reference drug. Compounds 6, 8, 10, and 16 showed excellent EGFR inhibitory activity and were further selected for screening as dual EGFR/HER2 inhibitors. The four selected compounds showed IC₅₀ ranging from 0.009 to 0.026 µM for EGFR and 0.021 to 0.069 µM for the HER2 enzyme. Compound 8 was found to be the most potent in this study with IC₅₀ 0.009 and 0.021 µM for EGFR and HER2, respectively.

Hit discovery of 4-amino-N-(4-(3-(trifluoromethyl)phenoxy)pyrimidin-5-yl)benzamide: A novel EGFR inhibitor from a designed small library

Searching for hit compounds within the huge chemical space resembles the attempt to find a needle in a haystack. Cheminformatics-guided selection of few representative molecules of a rationally designed virtual combinatorial library is a powerful tool to confront this challenge, speed up hit identification and cut off costs. Herein, this approach has been applied to identify hit compounds with novel scaffolds able to inhibit EGFR kinase. From a generated virtual library, six 4-aryloxy-5-aminopyrimidine scaffold-derived compounds were selected, synthesized and evaluated as hit EGFR inhibitors. 4-Aryloxy-5-benzamidopyrimidines inhibited EGFR with IC₅₀ 1.05-5.37 μM. Cell-based assay of the most potent EGFR inhibitor hit (10ac) confirmed its cytotoxicity against different cancerous cells. In spite of no EGFR, HER2 or VEGFR1 inhibition was elicited by 4-aryloxy-5-(thio)ureidopyrimidine derivatives, cell-based evaluation suggested them as antiproliferative hits acting by other mechanism(s). Molecular docking study provided a plausible explanation of incapability of 4-aryloxy-5-(thio)ureidopyrimidines to inhibit EGFR and suggested a reasonable binding mode of 4-aryloxy-5-benzamidopyrimidines which provides a basis to develop more optimized ligands.