Discovery of 3,5-substituted 6-azaindazoles as potent pan-Pim inhibitors

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

Herein, we report a pair of regioselective N 1- and N 2 -alkylations of a versatile indazole, methyl 5-bromo-1H-indazole-3-carboxylate (6) and the use of density functional theory (DFT) to evaluate their mechanisms. Over thirty N 1- and N 2-alkylated products were isolated in over 90% yield regardless of the conditions. DFT calculations suggest a chelation mechanism produces the N 1-substituted products when cesium is present and other non-covalent interactions (NCIs) drive the N 2-product formation. Methyl 1H-indazole-7-carboxylate (18) and 1H-indazole-3-carbonitrile (21) were also subjected to the reaction conditions and their mechanisms were evaluated. The N 1- and N 2-partial charges and Fukui indices were calculated for compounds 6, 18, and 21 via natural bond orbital (NBO) analyses which further support the suggested reaction pathways.

Pyrazolopyridine-based kinase inhibitors for anti-cancer targeted therapy

The need for effective cancer treatments continues to be a challenge for the biomedical research community. In this case, the advent of targeted therapy has significantly improved therapeutic outcomes. Drug discovery and development efforts targeting kinases have resulted in the approval of several small-molecule anti-cancer drugs based on ATP-mimicking heterocyclic cores. Pyrazolopyridines are a group of privileged heterocyclic cores in kinase drug discovery, which are present in several inhibitors that have been developed against various cancers. Notably, selpercatinib, glumetinib, camonsertib and olverembatinib have either received approval or are in late-phase clinical studies. This review presents the success stories employing pyrazolopyridine scaffolds as hinge-binding cores to address various challenges in kinase-targeted drug discovery research.

Research strategies of small molecules as chemotherapeutics to overcome multiple myeloma resistance

Multiple myeloma (MM), a cancer of plasma cells, is the second most common hematological malignancy which is characterized by aberrant plasma cells infiltration in the bone marrow and complex heterogeneous cytogenetic abnormalities. Over the past two decades, novel treatment strategies such as proteasome inhibitors, immunomodulators, and monoclonal antibodies have significantly improved the relative survival rate of MM patients. However, the development of drug resistance results in the majority of MM patients suffering from relapse, limited treatment options and uncontrolled disease progression after relapse. There are urgent needs to develop and explore novel MM treatment strategies to overcome drug resistance and improve efficacy. Here, we review the recent small molecule therapeutic strategies for MM, and introduce potential new targets and corresponding modulators in detail. In addition, this paper also summarizes the progress of multi-target inhibitor therapy and protein degradation technology in the treatment of MM.

Comprehensive Insights that Targeting PIM for Cancer Therapy: Prospects and Obstacles

Proviral integration sitea for Moloney-murine leukemia virus (PIM) kinases are a family of highly conserved serine/tyrosine kinases consisting of three members, PIM-1, PIM-2, and PIM-3. These kinases regulate a wide range of substrates through phosphorylation and affect key cellular processes such as transcription, translation, proliferation, apoptosis, and energy metabolism. Several PIM inhibitors are currently undergoing clinical trials, such as a phase I clinical trial of Uzanserti (5) for the treatment of relapsed diffuse large B-cell lymphoma that has been completed. The current focus encompasses the structural and biological characterization of PIM, ongoing research progress on small-molecule inhibitors undergoing clinical trials, and evaluation analysis of persisting challenges in this field. Additionally, the design and discovery of small-molecule inhibitors targeting PIM in recent years have been explored, with a particular emphasis on medicinal chemistry, aiming to provide valuable insights for the future development of PIM inhibitors.

Design, Synthesis and Antitumor Activity of 1H-indazole-3-amine Derivatives

A series of indazole derivatives were designed and synthesized by molecular hybridization strategy, and these compounds were evaluated the inhibitory activities against human cancer cell lines of lung (A549), chronic myeloid leukemia (K562), prostate (PC-3), and hepatoma (Hep-G2) by methyl thiazolyl tetrazolium (MTT) colorimetric assay. Among these, compound 6o exhibited a promising inhibitory effect against the K562 cell line with the IC₅₀ (50% inhibition concentration) value of 5.15 µM, and this compound showed great selectivity for normal cell (HEK-293, IC₅₀ = 33.2 µM). Moreover, compound 6o was confirmed to affect apoptosis and cell cycle possibly by inhibiting Bcl2 family members and the p53/MDM2 pathway in a concentration-dependent manner. Overall, this study indicates that compound 6o could be a promising scaffold to develop an effective and low-toxic anticancer agent.

Combining machine learning and structure-based approaches to develop oncogene PIM kinase inhibitors

Introduction: PIM kinases are targets for therapeutic intervention since they are associated with a number of malignancies by boosting cell survival and proliferation. Over the past years, the rate of new PIM inhibitors discovery has increased significantly, however, new generation of potent molecules with the right pharmacologic profiles were in demand that can probably lead to the development of Pim kinase inhibitors that are effective against human cancer.

Method: In the current study, a machine learning and structure based approaches were used to generate novel and effective chemical therapeutics for PIM-1 kinase. Four different machine learning methods, namely, support vector machine, random forest, k-nearest neighbour and XGBoost have been used for the development of models. Total, 54 Descriptors have been selected using the Boruta method.

Results: SVM, Random Forest and XGBoost shows better performance as compared to k-NN. An ensemble approach was implemented and, finally, four potential molecules (CHEMBL303779, CHEMBL690270, MHC07198, and CHEMBL748285) were found to be effective for the modulation of PIM-1 activity. Molecular docking and molecular dynamic simulation corroborated the potentiality of the selected molecules. The molecular dynamics (MD) simulation study indicated the stability between protein and ligands.

Discussion: Our findings suggest that the selected models are robust and can be potentially useful for facilitating the discovery against PIM kinase.

Recent Research Advances in Small-Molecule Pan-PIM Inhibitors

PIM kinase is consequently emerging as a promising target for cancer therapeutics and immunomodulation. PIM kinases are overexpressed in a variety of hematological malignancies and solid tumors, and their inhibition has become a strong therapeutic interest. Currently, some pan-PIM kinase inhibitors are being developed under different phases of clinical trials. Based on the different scaffold structures, they can be classified into various subclasses. The X-ray structure of the kinase complex outlines the rationale of hit compound confirmation in the early stage. Structure–activity relationships allow us to rationally explore chemical space and further optimize multiple physicochemical and biological properties. This review focuses on the discovery and development of small-molecule pan-PIM kinase inhibitors in the current research, and hopes to provide guidance for future exploration of the inhibitors.

A systematic review on active sites and functions of PIM-1 protein

The Proviral Integration of Molony murine leukemia virus (PIM)-1 protein contributes to the solid cancers and hematologic malignancies, cell growth, proliferation, differentiation, migration, and other life activities. Many studies have related these functions to its molecular structure, subcellular localization and expression level. However, recognition of specific active sites and their effects on the activity of this constitutively active kinase is still a challenge. Based on the close relationship between its molecular structure and functional activity, this review covers the specific residues involved in the binding of ATP and different substrates in its catalytic domain. This review then elaborates on the relevant changes in protein conformation and cell functions after PIM-1 binds to different substrates. Therefore, this intensive study can improve the understanding of PIM-1-regulated signaling pathways by facilitating the discovery of its potential phosphorylation substrates.

Evaluation of Substituted Pyrazole-Based Kinase Inhibitors in One Decade (2011-2020): Current Status and Future Prospects

Pyrazole has been recognized as a pharmacologically important privileged scaffold whose derivatives produce almost all types of pharmacological activities and have attracted much attention in the last decades. Of the various pyrazole derivatives reported as potential therapeutic agents, this article focuses on pyrazole-based kinase inhibitors. Pyrazole-possessing kinase inhibitors play a crucial role in various disease areas, especially in many cancer types such as lymphoma, breast cancer, melanoma, cervical cancer, and others in addition to inflammation and neurodegenerative disorders. In this article, we reviewed the structural and biological characteristics of the pyrazole derivatives recently reported as kinase inhibitors and classified them according to their target kinases in a chronological order. We reviewed the reports including pyrazole derivatives as kinase inhibitors published during the past decade (2011-2020).

Current progress, challenges and future prospects of indazoles as protein kinase inhibitors for the treatment of cancer

The indazole core is an interesting pharmacophore due to its applications in medicinal chemistry. In the past few years, this moiety has been used for the synthesis of kinase inhibitors. Many researchers have demonstrated the use of indazole derivatives as specific kinase inhibitors, including tyrosine kinase and serine/threonine kinases. A number of anticancer drugs with an indazole core are commercially available, e.g. axitinib, linifanib, niraparib, and pazopanib. Indazole derivatives are applied for the targeted treatment of lung, breast, colon, and prostate cancers. In this review, we compile the current development of indazole derivatives as kinase inhibitors and their application as anticancer agents in the past five years.

The Anticancer Activity of Indazole Compounds: A Mini Review

The incidence and mortality of cancer continue to grow since the current medical treatments often fail to produce a complete and durable tumor response and ultimately give rise to therapy resistance and tumor relapse. Heterocycles with potential therapeutic values are of great pharmacological importance, and among them, indazole moiety is a privileged structure in medicinal chemistry. Indazole compounds possess potential anticancer activity, and indazole-based agents such as, axitinib, lonidamine and pazopanib have already been employed for cancer therapy, demonstrating indazole compounds as useful templates for the development of novel anticancer agents. The aim of this review is to present the main aspects of exploring anticancer properties, such as the structural modifications, the structure-activity relationship and mechanisms of action, making an effort to highlight the importance and therapeutic potential of the indazole compounds in the present anticancer agents.

Pim kinase inhibitors in cancer: medicinal chemistry insights into their activity and selectivity

The oncogenic Pim kinase proteins (Pim-1/2/3) regulate tumorigenesis through phosphorylating essential proteins that control cell cycle and proliferation. Pim kinase is a potential chemotherapeutic target in cancer and its inhibition is currently the focus of intensive drug design and development efforts. The distinctive presence of proline amino acids in the hinge region provides an opportunity to inhibit Pim kinase while conserving the physiological functions of other kinases and reducing the toxicity profiles of the inhibitors. Various Pim kinase inhibitors have been clinically evaluated for the treatment of hematological cancers, yet none has reached the clinic. In this review, we discuss the design and development of selective and potent Pim inhibitors with novel chemotypes focusing on structural features essential for high potency and selectivity.

Discovery of novel (+)-Usnic acid derivatives as potential anti-leukemia agents with pan-Pim kinases inhibitory activity

Usnic acid (UA) is the main secondary metabolite isolated from lichens, with moderate anticancer activity. A small group of (+)-UA derivatives characterized with flavanone moiety was designed and synthesized, and their anticancer activities were evaluated in leukemia cells. It was demonstrated that (+)-UA derivatives 6a-6g inhibited the proliferation of leukemia cells HL-60 and K562 with low micromolar IC₅₀ values. Mechanisms of action were investigated to find that 6g induced apoptosis in HL-60 and K562 cell lines, and affected the expression of MNK/eIF4E axis-related proteins, such as Mcl-1, p-eIF4E, p-4E-BP1. Finally, kinase inhibition assay suggested 6g was a potential inhibitor of pan-Pim kinases. Meanwhile, the blocking of phosphorylation of BAD and 4E-BP1 by 6g, together with the proposed binding mode of 6g with Pim-1 further confirmed its Pim inhibition effects. Our finding provides the sight towards the potential mechanism of (+)-UA derivatives 6g as anti-leukemia agents.

PIM kinase inhibitors: Structural and pharmacological perspectives

The PIM kinase, also known as serine/threonine kinase plays an important role in cancer biology and is found in three different isoforms namely PIM-1, PIM-2, and PIM-3. They are extensively distributed and are implicated in a variety of biological processes, including cell proliferation, cell differentiation, and apoptosis. They act as weak oncogene and whenever expressed in exacerbating forms are responsible for different types of human cancer. Recently, different isoforms of PIM kinase have been identified as a clinical biomarker and potential therapeutic target for personalized treatment of advanced cancer. The inhibition of PIM kinase has become a scientific interest and some inhibitors have been developed and/or are under different phases of clinical trials. Several medicinally privileged heterocyclic ring scaffolds such as pyrrole, pyrimidine, thiazolidine, benzofuran, indole, triazole, oxadiazole, and quinoline derivatives have been synthesized and evaluated for their PIM inhibitory activity. This review comprehensively focuses on pharmacological implications of PIM kinases in oncogenesis, structural insights of PIM inhibitors and their structure-activity relationships (SARs).

Recent Advances in Indazole-Containing Derivatives: Synthesis and Biological Perspectives

Indazole-containing derivatives represent one of the most important heterocycles in drug molecules. Diversely substituted indazole derivatives bear a variety of functional groups and display versatile biological activities; hence, they have gained considerable attention in the field of medicinal chemistry. This review aims to summarize the recent advances in various methods for the synthesis of indazole derivatives. The current developments in the biological activities of indazole-based compounds are also presented.

Characterizing the in vitro species differences in N-glucuronidation of a potent pan-PIM inhibitor GNE-924 containing a 3,5-substituted 6-azaindazole

1. Glucuronidation of amines has been shown to exhibit large species differences, where the activity is typically more pronounced in human than in many preclinical species such as rat, mouse, dog and monkey. The purpose of this work was to characterize the in vitro glucuronidation of GNE-924, a potent pan-PIM inhibitor, to form M1 using liver microsomes (LM) and intestinal microsomes (IM). 2. M1 formation kinetics varied highly across species and between liver and intestinal microsomes. In LM incubations, rat exhibited the highest rate of M1 formation (CL_int,app) at 140 ± 10 µL/min/mg protein, which was approximately 30-fold higher than human. In IM incubations, mouse exhibited the highest CL_int,app at 484 ± 40 µL/min/mg protein, which was >1000-fold higher than human. In addition, CL_int,app in LM was markedly higher than IM in human and monkey. In contrast, CL_int,app in IM was markedly higher than LM in dog and mouse. 3. Reaction phenotyping indicated that UGT1A1, UGT1A3, UGT1A9, UGT2B4 and the intestine-specific UGT1A10 contributed to the formation of M1. 4. This is one of the first reports showing that N-glucuronidation activity is significantly greater in multiple preclinical species than in humans, and suggests that extensive intestinal N-glucuronidation may limit the oral exposure of GNE-924.

Fragment-to-Lead Medicinal Chemistry Publications in 2015

Fragment-based drug discovery (FBDD) is now well-established as a technology for generating new chemical leads and drugs. This Miniperspective provides a tabulated overview of the fragment-to-lead literature published in the year 2015, together with a commentary on trends observed across the FBDD field during this time. It is hoped that this tabulated summary will provide a useful point of reference for both FBDD practitioners and the wider medicinal chemistry community.

Design, synthesis and structure activity relationship of potent pan-PIM kinase inhibitors derived from the pyridyl carboxamide scaffold

The Pim proteins (1, 2 and 3) are serine/threonine kinases that have been found to be upregulated in many hematological malignancies and solid tumors. As a result of overlapping functions among the three isoforms, inhibition of all three Pim kinases has become an attractive strategy for cancer therapy. Herein we describe our efforts in identifying potent pan-PIM inhibitors that are derived from our previously reported pyridyl carboxamide scaffold as part of a medicinal chemistry strategy to address metabolic stability.