Design, synthesis and biological evaluation of dual HDAC and VEGFR inhibitors as multitargeted anticancer agents

Bicyclic 2-aminopyrimidine derivatives as potent VEGFR-2 inhibitors and apoptosis Inducers: Structure-Guided design, synthesis, anticancer assessment, and in-silico exploration

Anticancer therapy focuses on VEGFR-2 inhibition to disrupt angiogenesis, a critical process that sustains tumor growth and metastasis. This study outlines the synthesis and biological evaluation of 14 newly designed compounds featuring a bicyclic 2-amino-pyrimidine scaffold. In-vitro VEGFR-2 inhibition showed that compounds 55 and 61 were more potent with IC50 of 0.035 μM and 0.043 μM respectively, compared to the reference drug Sorafenib, and revealed selectivity for VEGFR-2 over EGFR. Consequently, 55 and 61 displayed good antiproliferative activities against the tested cell lines A549 (IC50 = 2.67 and 2.71 μM, respectively) and HCT116 (IC50 = 10.87 and 12.17 μM, respectively). The most active compounds were further assessed for their ability to induce apoptosis and preferential effect on wound closure in A549 cells, investigated via the cell scratch assay. Moreover, these compounds substantially reduced the phosphorylation of ERK and AKT, two downstream targets of VEGFR-2. The CAM assay further verified the antiangiogenic potential of lead compounds, revealing a significant reduction of neovascularization. Molecular docking studies performed for compound 55 showed hydrogen bond interactions with Asp1046, Cys919, and Glu885, similar to FDA-approved sorafenib. Moreover, a 100 ns MD simulation confirmed the complex's stability, while other analyses, such as RMSD, RMSF, PCA, and FEL, were performed to characterize protein conformational variations. Thorough SAR analysis, along with findings of cytotoxic activities and in-vitro inhibition of VEGFR-2, supports the potential of these synthetic compounds as VEGFR-2 inhibitors.

The Role of HDAC6 in Glioblastoma Multiforme: A New Avenue to Therapeutic Interventions?

Despite the great advances in basic research results, glioblastoma multiforme (GBM) still remains an incurable tumour. To date, a GBM diagnosis is a death sentence within 15-18 months, due to the high recurrence rate and resistance to conventional radio- and chemotherapy approaches. The effort the scientific community is lavishing on the never-ending battle against GBM is reflected by the huge number of clinical trials launched, about 2003 on 10 September 2024. However, we are still far from both an in-depth comprehension of the biological and molecular processes leading to GBM onset and progression and, importantly, a cure. GBM is provided with high intratumoral heterogeneity, immunosuppressive capacity, and infiltrative ability due to neoangiogenesis. These features impact both tumour aggressiveness and therapeutic vulnerability, which is further limited by the presence in the tumour core of niches of glioblastoma stem cells (GSCs) that are responsible for the relapse of this brain neoplasm. Epigenetic alterations may both drive and develop along GBM progression and also rely on changes in the expression of the genes encoding histone-modifying enzymes, including histone deacetylases (HDACs). Among them, HDAC6-a cytoplasmic HDAC-has recently gained attention because of its role in modulating several biological aspects of GBM, including DNA repair ability, massive growth, radio- and chemoresistance, and de-differentiation through primary cilia disruption. In this review article, the available information related to HDAC6 function in GBM will be presented, with the aim of proposing its inhibition as a valuable therapeutic route for this deadly brain tumour.

Small molecules targeting HDAC6 for cancer treatment: Current progress and novel strategies

Histone deacetylase 6 (HDAC6) plays a crucial role in the initiation and progression of various cancers, as its overexpression is linked to tumor growth, invasion, migration, survival, apoptosis, and angiogenesis. Therefore, HDAC6 has emerged as an attractive target for anticancer drug discovery in the past decade. However, the development of conventional HDAC6 inhibitors has been hampered by their limited clinical efficacy, acquired resistance, and inability to inhibit non-enzymatic functions of HDAC6. To overcome these challenges, new strategies, such as dual-acting inhibitors, targeted protein degradation (TPD) technologies (including PROTACs, HyT), are essential to enhance the anticancer activity of HDAC6 inhibitors. In this review, we focus on the recent advances in the design and development of HDAC6 modulators, including isoform-selective HDAC6 inhibitors, HDAC6-based dual-target inhibitors, and targeted protein degraders (PROTACs, HyT), from the perspectives of rational design, pharmacodynamics, pharmacokinetics, and clinical status. Finally, we discuss the challenges and future directions for HDAC6-based drug discovery for cancer therapy.

Hydrazides as Inhibitors of Histone Deacetylases

In this Perspective, we have brought together available biological evidence on hydrazides as histone deacetylase inhibitors (HDACis) and as a distinct type of Zn-binding group (ZBG) to be reviewed for the first time in the literature. N-Alkyl hydrazides have transformed the field, providing innovative and practical chemical tools for selective and effective inhibition of specific histone deacetylase (HDAC) enzymes, in addition to the usual hydroxamic acid and o-aminoanilide ZBG-bearing HDACis. This has enabled efficient targeting of neurodegenerative diseases such as Alzheimer's disease, cancer, cardiovascular diseases, and protozoal pathologies.

Recent advances and future directions on small molecule VEGFR inhibitors in oncological conditions

"A journey of mixed emotions" is a quote that best describes the progress chart of vascular endothelial growth factor receptor (VEGFR) inhibitors as cancer therapeutics in the last decade. Exhilarated with the Food and Drug Administration (FDA) approvals of numerous VEGFR inhibitors coupled with the annoyance of encountering the complications associated with their use, drug discovery enthusiasts are on their toes with an unswerving determination to enhance the rate of translation of VEGFR inhibitors from preclinical to clinical stage. The recently crafted armory of VEGFR inhibitors is a testament to their growing dominance over other antiangiogenic therapies for cancer treatment. This review perspicuously underscores the earnest attempts of the researchers to extract the antiproliferative potential of VEGFR inhibitors through the design of mechanistically diverse structural assemblages. Moreover, this review encompasses sections on structural/molecular properties and physiological functions of VEGFR, FDA-approved VEGFR inhibitors, and hurdles restricting the activity range/clinical applicability of VEGFR targeting antitumor agents. In addition, tactics to overcome the limitations of VEGFR inhibitors are discussed. A clear-cut viewpoint transmitted through this compilation can provide practical directions to push the cart of VEGFR inhibitors to advanced-stage clinical investigations in diverse malignancies.

Exploring the role of histone deacetylase and histone deacetylase inhibitors in the context of multiple myeloma: mechanisms, therapeutic implications, and future perspectives

Histone deacetylase inhibitors (HDACis) are a significant category of pharmaceuticals that have developed in the past two decades to treat multiple myeloma. Four drugs in this category have received approval from the U.S. Food and Drug Administration (FDA) for use: Panobinonstat (though canceled by the FDA in 2022), Vorinostat, Belinostat and Romidepsin. The efficacy of this group of drugs is attributed to the disruption of many processes involved in tumor growth through the inhibition of histone deacetylase, and this mode of action leads to significant anti-multiple myeloma (MM) activity. In MM, inhibition of histone deacetylase has many downstream consequences, including suppression of NF-κB signaling and HSP90, upregulation of cell cycle regulators (p21, p53), and downregulation of antiapoptotic proteins including Bcl-2. Furthermore, HDACis have a variety of direct and indirect oxidative effects on cellular DNA. HDAC inhibitors enhance normal immune function, thereby decreasing the proliferation of malignant plasma cells and promoting autophagy. The various biological effects of inhibiting histone deacetylase have a combined or additional impact when used alongside other chemotherapeutic and targeted drugs for multiple myeloma. This helps to decrease resistance to treatment. Combination treatment regimens that include HDACis have become an essential part of the therapy for multiple myeloma. These regimens incorporate drugs from other important classes of anti-myeloma agents, such as immunomodulatory drugs (IMiDs), conventional chemotherapy, monoclonal antibodies, and proteasome inhibitors. This review provides a comprehensive evaluation of the clinical efficacy and safety data pertaining to the currently approved histone deacetylase inhibitors, as well as an explanation of the crucial function of histone deacetylase in multiple myeloma and the characteristics of the different histone deacetylase inhibitors. Moreover, it provides a concise overview of the most recent developments in the use of histone deacetylase inhibitors for treating multiple myeloma, as well as potential future uses in treatment.

Recent developments of hydroxamic acid hybrids as potential anti-breast cancer agents

Histone deacetylase inhibitors not only possess favorable effects on modulating tumor microenvironment and host immune cells but also can reactivate the genes silenced due to deacetylation and chromatin condensation. Hydroxamic acid hybrids as promising histone deacetylase inhibitors have the potential to address drug resistance and reduce severe side effects associated with a single drug molecule due to their capacity to simultaneously modulate multiple targets in cancer cells. Accordingly, rational design of hydroxamic acid hybrids may provide valuable therapeutic interventions for the treatment of breast cancer. This review aimed to provide insights into the in vitro and in vivo anti-breast cancer therapeutic potential of hydroxamic acid hybrids, together with their mechanisms of action and structure-activity relationships, covering articles published from 2020 to the present.

SynergyX: a multi-modality mutual attention network for interpretable drug synergy prediction

Discovering effective anti-tumor drug combinations is crucial for advancing cancer therapy. Taking full account of intricate biological interactions is highly important in accurately predicting drug synergy. However, the extremely limited prior knowledge poses great challenges in developing current computational methods. To address this, we introduce SynergyX, a multi-modality mutual attention network to improve anti-tumor drug synergy prediction. It dynamically captures cross-modal interactions, allowing for the modeling of complex biological networks and drug interactions. A convolution-augmented attention structure is adopted to integrate multi-omic data in this framework effectively. Compared with other state-of-the-art models, SynergyX demonstrates superior predictive accuracy in both the General Test and Blind Test and cross-dataset validation. By exhaustively screening combinations of approved drugs, SynergyX reveals its ability to identify promising drug combination candidates for potential lung cancer treatment. Another notable advantage lies in its multidimensional interpretability. Taking Sorafenib and Vorinostat as an example, SynergyX serves as a powerful tool for uncovering drug-gene interactions and deciphering cell selectivity mechanisms. In summary, SynergyX provides an illuminating and interpretable framework, poised to catalyze the expedition of drug synergy discovery and deepen our comprehension of rational combination therapy.

Hydroxamic acid hybrids: Histone deacetylase inhibitors with anticancer therapeutic potency

Histone deacetylases (HDACs), a class of enzymes responsible for the removal of acetyl functional groups from the lysine residues in the amino-terminal tails of core histones, play a critical role in the modulation of chromatin architecture and the regulation of gene expression. Dysregulation of HDAC expression has been closely associated with the development of various cancers. Histone deacetylase inhibitors (HDACis) could regulate diverse cellular pathways, cause cell cycle arrest, and promote programmed cell death, making them promising avenues for cancer therapy with potent efficacy and favorable toxicity profiles. Hybrid molecules incorporating two or more pharmacophores in one single molecule, have the potential to simultaneously inhibit two distinct cancer targets, potentially overcome drug resistance and minimize drug-drug interactions. Notably, hydroxamic acid hybrids, exemplified by fimepinostat and tinostamustine as potential HDACis, could exert the anticancer effects through induction of apoptosis, differentiation, and growth arrest in cancer cells, representing useful scaffolds for the discovery of novel HDACis. The purpose of this review is to summarize the current scenario of hydroxamic acid hybrids as HDACis with anticancer therapeutic potential developed since 2020 to facilitate further rational exploitation of more effective candidates.

Technologies of targeting histone deacetylase in drug discovery: Current progress and emerging prospects

Histone deacetylases (HDACs) catalyze the hydrolysis of acetyl-l-lysine side chains in histones and non-histones, which are key to epigenetic regulation in humans. Targeting HDACs has emerged as a promising strategy for treating various types of cancer, including myeloma and hematologic malignancies. At present, numerous small molecule inhibitors targeting HDACs are actively being investigated in clinical trials. Despite their potential efficacy in cancer treatment, HDAC inhibitors suffer from multi-directional selectivity and preclinical resistance issues. Hence, developing novel inhibitors based on cutting-edge medicinal chemistry techniques is essential to overcome these limitations and improve clinical outcomes. This manuscript presents an extensive overview of the properties and biological functions of HDACs in cancer, provides an overview of the current state of development and limitations of clinical HDAC inhibitors, and analyzes a range of innovative medicinal chemistry techniques that are applied. These techniques include selective inhibitors, dual-target inhibitors, proteolysis targeting chimeras, and protein-protein interaction inhibitors.

Design, synthesis and biological evaluation of VEGFR-2/HDAC dual inhibitors as multitargeted antitumor agents based on fruquintinib and vorinostat

Herein, a series of 4-(benzofuran-6-yloxy)quinazoline derivatives as VEGFR-2/HDAC dual inhibitors were designed and synthesized based on fruquintinib and vorinostat. Among them, compound 13 exhibited potent inhibitory activity against VEGFR-2 and HDAC1 with IC50 values of 57.83 nM and 9.82 nM, and displayed moderate to significant antiproliferative activity against MCF-7, A549, HeLa and HUVEC. The cellular mechanism studies revealed that compound 13 arrested the cell cycle at the S and G2 phases, and induced significant apoptosis in HeLa cells. Tube formation assay in HUVECs demonstrated that 13 had a significant anti-angiogenic effect. Additionally, a molecular docking study supported the initial design strategy. These results highlighted that 13 was a valuable VEGFR-2/HDAC dual inhibitor and deserved further study for cancer therapy.

Recent development of multi-target VEGFR-2 inhibitors for the cancer therapy

Vascular epidermal growth factor receptor-2 (VEGFR-2), as an important tyrosine transmembrane protein, plays an important role in regulating endothelial cell proliferation and migration, regulating angiogenesis and other biological functions. VEGFR-2 is aberrantly expressed in many malignant tumors, and it is also related to the occurrence, development, and growth of tumors and drug resistance. Currently, there are nine VEGFR-2 targeted inhibitors approved by US.FDA for clinical use as anticancer drugs. Due to the limited clinical efficacy and potential toxicity of VEGFR inhibitors, it is necessary to develop new strategies to improve the clinical efficacy of VEGFR inhibitors. The development of multitarget therapy, especially dual-target therapy, has become a hot research field of cancer therapy, which may provide an effective strategy with higher therapeutic efficacy, pharmacokinetic advantages and low toxicity. Many groups have reported that the therapeutic effects could be improved by simultaneously inhibiting VEGFR-2 and other targets, such as EGFR, c-Met, BRAF, HDAC, etc. Therefore, VEGFR-2 inhibitors with multi-targeting capabilities have been considered to be promising and effective anticancer agents for cancer therapy. In this work, we reviewed the structure and biological functions of VEGFR-2, and summarized the drug discovery strategies, and inhibitory activities of VEGFR-2 inhibitors with multi-targeting capabilities reported in recent years. This work might provide the reference for the development of VEGFR-2 inhibitors with multi-targeting capabilities as novel anticancer agents.

Recent progress on vascular endothelial growth factor receptor inhibitors with dual targeting capabilities for tumor therapy

Vascular endothelial growth factor receptors (VEGFRs) are a family of receptor protein tyrosine kinases that play an important role in the regulation of tumor-induced angiogenesis. Currently, VEGFR inhibitors have been widely used in the treatment of various tumors. However, current VEGFR inhibitors are limited to a certain extent due to limited clinical efficacy and potential toxicity, which hinder their clinical application. Thus, the development of new strategies to improve the clinical outcomes and minimize the toxic effects of VEGFR inhibitors is required. Given the synergistic effect of VEGFR and other therapies in tumor development and progression, VEGFR dual-target inhibitors are becoming an attractive approach due to their favorable pharmacodynamics, low toxicity, and anti-resistant effects. This perspective provides an overview of the development of VEGFR dual-target inhibitors from multiple aspects, including rational target combinations, drug discovery strategies, structure–activity relationships and future directions.