BAY 1000394, a novel cyclin-dependent kinase inhibitor, with potent antitumor activity in mono- and in combination treatment upon oral application

Photocatalytic Synthesis and Functionalization of Sulfones, Sulfonamides and Sulfoximines

Sulfur(VI)-based functional groups are popular scaffolds in a wide variety of research fields including synthetic and medicinal chemistry, as well as chemical biology. The growing interest in sulfur(VI)-containing molecules has motivated the scientific community to explore new methods to synthesize and modify them. Here, photocatalysis plays a key role granting access to new types of reactivity under mild reaction conditions. In this Perspective, we present a selection of works reported in the last six years focused on the photocatalytic assembly and reactivity of sulfones, sulfonamides, and sulfoximines. We addressed the key synthetic intermediates for each transformation, while discussing limitations and strength points of the protocols. Future directions of the field are finally presented.

Innovative On-DNA Synthesis of Sulfides and Sulfoximines: Enriching the DEL Synthesis Toolbox

DNA-encoded library (DEL) technologies enable the fast exploration of gigantic chemical space to identify ligands for the target protein of interest and have become a powerful hit finding tool for drug discovery projects. However, amenable DEL chemistry is restricted to a handful of reactions, limiting the creativity of drug hunters. Here, we describe a new on-DNA synthetic pathway to access sulfides and sulfoximines. These moieties, usually contemplated as challenging to achieve through alkylation and oxidation, can now be leveraged in routine DEL selection campaigns.

Expression of cyclin-dependent kinase 9 is positively correlated with the autophagy level in colon cancer

BACKGROUND

Cyclin-dependent kinase 9 (CDK9) expression and autophagy in colorectal cancer (CRC) tissues has not been widely studied. CDK9, a key regulator of transcription, may influence the occurrence and progression of CRC. The expression of autophagy-related genes BECN1 and drug resistance factor ABCG2 may also play a role in CRC. Under normal physiological conditions, autophagy can inhibit tumorigenesis, but once a tumor forms, autophagy may promote tumor growth. Therefore, understanding the relationship between autophagy and cancer, particularly how autophagy promotes tumor growth after its formation, is a key motivation for this research.

AIM

To investigate the relationship between CDK9 expression and autophagy in CRC, assess differences in autophagy between left and right colon cancer, and analyze the associations of autophagy-related genes with clinical features and prognosis.

METHODS

We collected tumor tissues and paracarcinoma tissues from colon cancer patients with liver metastasis to observe the level of autophagy in tissues with high levels of CDK9 and low levels of CDK9. We also collected primary tissue from left and right colon cancer patients with liver metastasis to compare the autophagy levels and the expression of BECN1 and ABCG2 in the tumor and paracarcinoma tissues.

RESULTS

The incidence of autophagy and the expression of BECN1 and ABCG2 were different in left and right colon cancer, and autophagy might be involved in the occurrence of chemotherapy resistance. Further analysis of the relationship between the expression of autophagy-related genes CDK9, ABCG2, and BECN1 and the clinical features and prognosis of colorectal cancer showed that the high expression of CDK9 indicated a poor prognosis in colorectal cancer.

CONCLUSION

This study laid the foundation for further research on the combination of CDK9 inhibitors and autophagy inhibitors in the treatment of patients with CRC.

Asymmetric synthesis of sulfoximines, sulfonimidoyl fluorides and sulfonimidamides enabled by an enantiopure bifunctional S(VI) reagent

An increased interest to expand three-dimensional chemical space for the design of new materials and medicines has created a demand for isosteric replacement groups of commonly used molecular functionality. The structural and chemical properties of chiral S(VI) functional groups provide unique spatial and electronic features compared with their achiral sulfur- and carbon-based counterparts. Manipulation of the S(VI) centre to introduce structural variation with stereochemical control has remained a synthetic challenge. The stability of sulfonimidoyl fluorides and the efficiency of sulfur fluorine exchange chemistry has enabled the development of the enantiopure bifunctional S(VI) transfer reagent t-BuSF to overcome current synthetic limitations. Here, we disclose a reagent platform that serves as a chiral sulfur fluorine exchange template for the rapid asymmetric synthesis of over 70 sulfoximines, sulfonimidoyl fluorides and sulfonimidamides with excellent enantiomeric excess and good overall yields. Furthermore, the practical utility of the bifunctional S(VI) transfer reagent was demonstrated in the syntheses of enantiopure pharmaceutical intermediates and analogues.

Mask and Release Strategy-Enabled Diversity-Oriented Synthesis for DNA-Encoded Library

An ideal DNA-encoded library (DEL) selection requires the library to consist of diverse core skeletons and cover chemical space as much as possible. However, the lack of efficient on-DNA synthetic approaches toward core skeletons has greatly restricted the diversity of DEL. To mitigate this issue, this work disclosed a "Mask & Release" strategy to streamline the challenging on-DNA core skeleton synthesis. N-phenoxyacetamide is used as a masked phenol and versatile directing group to mediate diversified DNA-compatible C-H functionalization, introducing the 1st-dimensional diversity at a defined site, and simultaneously releasing the phenol functionality, which can facilitate the introduction of the 2nd diversity. This work not only provides a set of efficient syntheses toward DNA-conjugated drug-like core skeletons such as ortho-alkenyl/sulfiliminyl/cyclopropyl phenol, benzofuran, dihydrobenzofuran but also provides a paradigm for on-DNA core skeleton synthetic method development.

C-SuFEx linkage of sulfonimidoyl fluorides and organotrifluoroborates

Sulfur(VI) fluoride exchange, a new type of linkage reaction, has excellent potential for application in functional molecule linkage to prepare pharmaceuticals, biomolecules, and polymers. Herein, a C-SuFEx reaction is established to achieve fast (in minutes) linkage between sulfonimidoyl fluorides and aryl/alkyl organotrifluoroborates. Potassium organotrifluoroborates are instantaneously activated via a substoichiometric amount of trimethylsilyl triflate to afford organodifluoroboranes, releasing BF3 as an activating reagent in situ. This sulfur(VI) fluoride exchange technique is capable of forming S(VI)-C(alkyl), S(VI)-C(alkenyl) and S(VI)-C(aryl) bonds, demonstrating its broad scope. Natural products and pharmaceuticals with sensitive functional groups, such as valdecoxib, celecoxib and diacetonefructose, are compatible with this protocol, allowing the formation of diverse sulfoximines.

Rapid Access to Densely Functionalized Cyclopentenyl Sulfoximines through a Sc-Catalyzed Aza-Piancatelli Reaction

Sulfoximines make up a class of compounds of growing interest for crop science and medicinal chemistry, but methods for directly incorporating them into complex molecular scaffolds are lacking. Here we report a scandium-catalyzed variant of the aza-Piancatelli cyclization that can directly incorporate sulfoximines as nucleophiles rather than the classical aniline substrates. Starting from 2-furylcarbinols and sulfoximines, the reaction provides direct access to 4-sulfoximinocyclopentenones, a new scaffold bearing cyclopentenone and sulfoximine motifs, both of interest for bioactive compounds.

Photocatalytic N-Alkylation of NH-Diaryl Sulfondiimines via Anti-Markovnikov Hydroamination with Styrenes

Sulfondiimines, which are isoelectronic with sulfones and sulfoximines, represent a neglected yet intriguing pharmacophore in the discovery program. Herein, we present a facile and mild photocatalytic anti-Markovnikov hydroamination of styrenes for the construction of N-alkylated sulfondiimines with primary, secondary, and tertiary alkyl substituents. A sulfondiimine-derived analogue of the marketed drug Vioxx was synthesized using this method as the key step.

Synthesis of Sulfilimines via Selective S-C Bond Formation in Water

Sulfilimines are valuable compounds both in organic synthesis and in pharmaceuticals. Here we developed a mild and simplified method for preparation of sulfilimines via selective S-C bond formation rather than traditional S-N bond formation. The method is both attractive and useful for the following reasons: it uses a readily available alkylation reagent such alkyl bromide or alkyl iodide, it uses water as solvent, it is easy to perform, and it is convenient for late-stage diversification of drugs.

CDK4/6 Inhibitors in Pancreatobiliary Cancers: Opportunities and Challenges

Existing treatment strategies for pancreatobiliary malignancies are limited. Nowadays, surgery is the only path to cure these types of cancer, but only a small number of patients present with resectable tumors at the time of diagnosis. The notoriously poor prognosis, lack of diverse treatment options associated with pancreaticobiliary cancers, and their resistance to current therapies reflect the urge for the development of novel therapeutic targets. Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have emerged as an attractive therapeutic strategy in a number of cancers since their approval for treatment in patients with ER+/HER- breast cancer in combination with antiestrogens. In this article, we discuss the therapeutic potential of CDK4/6 inhibitors in pancreatobiliary cancers, notably cholangiocarcinoma and pancreatic ductal adenocarcinoma.

Synthesis of Chiral Sulfoximines via Iridium-Catalyzed Regio- and Enantioselective C-H Borylation: A Remarkable Sidearm Effect of Ligand

Transition metal-catalyzed enantioselective C-H activation of prochiral sulfoximines for non-annulated products remains a formidable challenge. We herein report iridium-catalyzed enantioselective C-H borylation of N-silyl diaryl sulfoximines using a well-designed chiral bidentate boryl ligand with a bulky side arm. This method is capable of accommodating a broad range of substrates under mild reaction conditions, affording a vast array of chiral sulfoximines with high enantioselectivities. We also demonstrated the synthetic utility on a preparative-scale C-H borylation for diverse downstream transformations, including the synthesis of chiral version of bioactive molecules. Computational studies showed that the bulky side arm of the ligand confers high regio- and enantioselectivity through steric effect.

Drug repositioning via host-pathogen protein-protein interactions for the treatment of cervical cancer

Introduction

Integrating interaction data with biological knowledge can be a critical approach for drug development or drug repurposing. In this context, host-pathogen-protein-protein interaction (HP-PPI) networks are useful instrument to uncover the phenomena underlying therapeutic effects in infectious diseases, including cervical cancer, which is almost exclusively due to human papillomavirus (HPV) infections. Cervical cancer is one of the second leading causes of death, and HPV16 and HPV18 are the most common subtypes worldwide. Given the limitations of traditionally used virus-directed drug therapies for infectious diseases and, at the same time, recent cancer statistics for cervical cancer cases, the need for innovative treatments becomes clear.

Methods

Accordingly, in this study, we emphasize the potential of host proteins as drug targets and identify promising host protein candidates for cervical cancer by considering potential differences between HPV subtypes (i.e., HPV16 and HPV18) within a novel bioinformatics framework that we have developed. Subsequently, subtype-specific HP-PPI networks were constructed to obtain host proteins. Using this framework, we next selected biologically significant host proteins. Using these prominent host proteins, we performed drug repurposing analysis. Finally, by following our framework we identify the most promising host-oriented drug candidates for cervical cancer.

Results

As a result of this framework, we discovered both previously associated and novel drug candidates, including interferon alfacon-1, pimecrolimus, and hyaluronan specifically for HPV16 and HPV18 subtypes, respectively.

Discussion

Consequently, with this study, we have provided valuable data for further experimental and clinical efforts and presented a novel bioinformatics framework that can be applied to any infectious disease.

Rapid and Scalable Halosulfonylation of Strain-Release Reagents

Sulfonylated aromatics are commonplace motifs in drugs and agrochemicals. However, methods for the direct synthesis of sulfonylated non-classical arene bioisosteres, which could improve the physicochemical properties of drug and agrochemical candidates, are limited. Here we report a solution to this challenge: a one-pot halosulfonylation of [1.1.1]propellane, [3.1.1]propellane and bicyclo[1.1.0]butanes that proceeds under practical, scalable and mild conditions. The sulfonyl halides used in this chemistry feature aryl, heteroaryl and alkyl substituents, and are conveniently generated in situ from readily available sulfinate salts and halogen atom sources. This methodology enables the synthesis of an array of pharmaceutically and agrochemically relevant halogen/sulfonyl-substituted bioisosteres and cyclobutanes, on up to multidecagram scale.

N-Cyano sulfilimine functional group as a nonclassical amide bond bioisostere in the design of a potent analogue to anthranilic diamide insecticide

To explore the potential of the N-cyano sulfilimine group as an amide bond isostere, a derivative of the blockbuster anthranilic diamide, chlorantramiliprole, was synthesized and evaluated with regard to its physicochemical properties, permeability, and biological activity. Given the combination of N-cyano sulfilimine chlorantraniliprole 1 and its strong hydrogen bond acceptor character, high permeability, and excellent insecticidal activity, the N-cyano sulfilimine functional group could be considered as an amide bond isostere.

Anti-cancer drug molecules targeting cancer cell cycle and proliferation

Cancer, a vicious clinical burden that potentiates maximum fatality for humankind, arises due to unregulated excessive cell division and proliferation through an eccentric expression of cell cycle regulator proteins. A set of evolutionarily conserved machinery controls the cell cycle in an extremely precise manner so that a cell that went through the cycle can produce a genetically identical copy. To achieve perfection, several checkpoints were placed in the cycle for surveillance; so, errors during the division were rectified by the repair strategies. However, irreparable damage leads to exit from the cell cycle and induces programmed cell death. In comparison to a normal cell, cancer cells facilitate the constitutive activation of many dormant proteins and impede negative regulators of the checkpoint. Extensive studies in the last few decades on cell division and proliferation of cancer cells elucidate the molecular mechanism of the cell-cycle regulators that are often targeted for the development of anti-cancer therapy. Each phase of the cell cycle has been regulated by a unique set of proteins including master regulators Cyclins, and CDKs, along with the accessory proteins such as CKI, Cdc25, error-responsive proteins, and various kinase proteins mainly WEE1 kinases, Polo-like kinases, and Aurora kinases that control cell division. Here in this chapter, we have analytically discussed the role of cell cycle regulators and proliferation factors in cancer progression and the rationale of using various cell cycle-targeting drug molecules as anti-cancer therapy.

Nuak kinase signaling in development and disease of the central nervous system

Protein kinases represent important signaling hubs for a variety of biological functions. Many kinases are traditionally studied for their roles in cancer cell biology, but recent advances in neuroscience research show repurposed kinase function to be important for nervous system development and function. Two members of the AMP-activated protein kinase (AMPK) related family, NUAK1 and NUAK2, have drawn attention in neuroscience due to their mutations in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia, and intellectual disability (ID). Furthermore, Nuak kinases have also been implicated in tauopathy and other disorders of aging. This review highlights what is known about the Nuak kinases in nervous system development and disease and explores the possibility of Nuak kinases as targets for therapeutic innovation.

Applications and mechanisms of the cyclin-dependent kinase 4/6 inhibitor, PD-0332991, in solid tumors

Abnormal CDK4/6-Rb-E2F signal transduction is a common finding in tumors and is a driving factor for the excessive proliferation of various tumor cells. PD-0332991, a highly specific, small molecule inhibitor for CDK4 and 6, has been shown to inhibit tumor growth by abrogating the phosphorylating capacity of CDK4/6 and suppressing Rb phosphorylation. It has been promoted for the treatment of breast cancer and potentially for other tumor types such as liver cancers, lung cancers and sarcomas. Due to the risk of monotherapy resistance, PD-0332991 is commonly used in combination with other drugs. Such combination treatments have proved able to inhibit tumor proliferation more effectively, induce stronger senescence and apoptosis, and enhance the efficiency of immunotherapy. Therefore, tumor cells with senescence induced by PD-0332991 are now used as ideal screening tools of cytolytic drugs with more efficient and thorough anti-tumor properties. With more extensive understandings about the branching points between senescence and apoptosis, it is possible to refine the dosage of PD-0332991. Better characterization of resistant cells, of inhibitors and of adverse effects such as leukopenia are needed to overcome obstacles in the use of PD-0332991. In this review of PD-0332991 research, we hope to provide guidance of transitions from laboratory findings to clinical applications of PD-0332991 and to facilitate PD-0332991-based multi-inhibitor combination therapies for various tumors.

Discovery of 5,7-Dihydro-6H-pyrrolo[2,3-d]pyrimidin-6-ones as Highly Selective CDK2 Inhibitors

A series of exceptionally selective CDK2 inhibitors are described. Starting from an HTS hit, we successfully scaffold hopped to a 5,7-dihydro-6H-pyrrolo[2,3-d]pyrimidin-6-one core structure, which imparted a promising initial selectivity within the CDK family. Extensive further SAR identified additional factors that drove selectivity to above 200× for CDKs 1/4/6/7/9. General kinome selectivity was also greatly improved. Finally, use of in vivo metabolite identification allowed us to pinpoint sulfonamide dealkylation as the primary metabolite, which was ameliorated through the deuterium effect.

CDK9 Inhibitors in Cancer Research

Cyclin dependent kinase 9 (CDK9) played an essential role in regulating transcriptional elongation. Aberrations in CDK9 activity have been observed in various cancers, which made CDK9 was an attractive therapeutic...

Transcriptional cyclin-dependent kinases: Potential drug targets in cancer therapy

In the wake of the development of the concept of cell cycle and its limiting points, cyclin-dependent kinases (CDKs) are considered to play a central role in regulating cell cycle progression. Recent studies have strongly demonstrated that CDKs also has multiple functions, especially in response to extracellular and intracellular signals by interfering with transcriptional events. Consequently, how to inhibit their function has been a hot research topic. It is worth noting that the key role of CDKs in regulating transcription has been explored in recent years, but its related pharmacological targets are less developed, and most inhibitors have not entered the clinical stage. Accordingly, this perspective focus on the biological functions of transcription related CDKs and their complexes, some key upstream and downstream signals, and inhibitors for cancer treatment in recent years. In addition, some corresponding combined treatment strategies will provide a more novel perspective for future cancer remedy.

Synthesis and Transformations of NH-Sulfoximines

Recent years have seen a marked increase in the occurrence of sulfoximines in the chemical sciences, often presented as valuable motifs for medicinal chemistry. This has been prompted by both pioneering works taking sulfoximine containing compounds into clinical trials and the concurrent development of powerful synthetic methods. This review covers recent developments in the synthesis of sulfoximines concentrating on developments since 2015. This includes extensive developments in both S-N and S-C bond formations. Flow chemistry processes for sulfoximine synthesis are also covered. Finally, subsequent transformations of sulfoximines, particularly in N-functionalization are reviewed, including N-S, N-P, N-C bond forming processes and cyclization reactions.

Advances in Pyrazole Based Scaffold as Cyclin-Dependent Kinase 2 Inhibitors for the Treatment of Cancer

The transformation of a normal cell into a tumor cell is one of the initial steps in cell cycle deregulation. The cell cycle is regulated by cyclin-dependent kinases (CDKs) that belong to the protein kinase family. CDK2 is an enchanting target for specific genotypes tumors since cyclin E is selective for CDK2 and the deregulation of specific cancer forms. Thus, CDKs inhibitor specifically CDK2/cyclin A-E has the potential to be a valid cancer target as per the currently undergoing clinical trials. Mostly pyrazole scaffolds have shown selectivity and potency for CDK2 inhibitors. This review demonstrates pyrazole and pyrazole fused with other heterocyclic rings for anti-proliferative activity. Based on the in vitro and molecular docking studies, the IC50 value of various hybrids is revealed to display the most potent analogs for CDK2 inhibition. Thus, the review emphasizes various lead analogs of pyrazole hybrids which can be found to be very potent and selective for anti-cancer drugs.

Analyzing the scaffold diversity of cyclin-dependent kinase inhibitors and revisiting the clinical and preclinical pipeline

Kinases have gained an important place in the list of vital therapeutic targets because of their overwhelming clinical success in the last two decades. Among various clinically validated kinases, the cyclin-dependent kinases (CDK) are one of the extensively studied drug targets for clinical development. Food and Drug Administration has approved three CDK inhibitors for therapeutic use, and at least 27 inhibitors are under active clinical development. In the last decade, research and development in this area took a rapid pace, and thus the analysis of scaffold diversity is essential for future drug design. Available reviews lack the systematic study and discussion on the scaffold diversity of CDK inhibitors. Herein we have reviewed and critically analyzed the chemical diversity present in the preclinical and clinical pipeline of CDK inhibitors. Our analysis has shown that although several scaffolds represent CDK inhibitors, only the amino-pyrimidine is a well-represented scaffold. The three-nitrogen framework of amino-pyrimidine is a fundamental hinge-binding unit. Further, we have discussed the selectivity aspects among CDKs, the clinical trial dose-limiting toxicities, and highlighted the most advanced clinical candidates. We also discuss the changing paradigm towards selective inhibitors and an overview of ATP-binding pockets of all druggable CDKs. We carefully analyzed the clinical pipeline to unravel the candidates that are currently under active clinical development. In addition to the plenty of dual CDK4/6 inhibitors, there are many selective CDK7, CDK9, and CDK8/19 inhibitors in the clinical pipeline.

Targeting Protein Kinases Degradation by PROTACs

Kinase dysregulation is greatly associated with cell proliferation, migration and survival, indicating the importance of kinases as therapeutic targets for anticancer drug development. However, traditional kinase inhibitors binding to catalytic or allosteric sites are associated with significant challenges. The emergence of resistance and targeting difficult-to-degrade and multi-domain proteins are significant limiting factors affecting the efficacy of targeted anticancer drugs. The next-generation treatment approaches seem to have overcome these concerns, and the use of proteolysis targeting chimera (PROTAC) technology is one such method. PROTACs bind to proteins of interest and recruit E3 ligase for degrading the whole target protein via the ubiquitin-proteasome pathway. This review provides a detailed summary of the most recent signs of progress in PROTACs targeting different kinases, primarily focusing on new chemical entities in medicinal chemistry.

Copanlisib synergizes with conventional and targeted agents including venetoclax in B- and T-cell lymphoma models

Copanlisib is a pan-class I phosphoinositide 3-kinase (PI3K) inhibitor with preferred activity toward PI3Kα and PI3Kδ. Despite the clear overall clinical benefit, the number of patients achieving complete remissions with the single agent is relatively low, a problem shared by the vast majority of targeted agents. Here, we searched for novel copanlisib-based combinations. Copanlisib was tested as a single agent, in combination with an additional 17 drugs in 26 cell lines derived from mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and T-cell lymphomas. In vivo experiments, transcriptome analyses, and immunoblotting experiments were also performed. Copanlisib as a single agent showed in vitro dose-dependent antitumor activity in the vast majority of the models. Combination screening identified several compounds that synergized with copanlisib. The strongest combination was with the B-cell lymphoma 2 (BCL2) inhibitor venetoclax. The benefit of the combination over single agents was also validated in an MZL xenograft model and in MCL primary cells, and was due to increased induction of apoptosis, an effect likely sustained by the reduction of the antiapoptotic proteins myeloid cell leukemia 1 (MCL1) and BCL-XL, observed in MCL and MZL cell lines, respectively. These data supported the rationale for the design of the Swiss Group for Clinical Cancer Research (SAKK) 66/18 phase 1 study currently exploring the combination of copanlisib and venetoclax in relapsed/refractory lymphomas.

Small Molecule CDK Inhibitors for the Therapeutic Management of Cancer

Cyclin-dependent kinases (CDKs) are a group of multifunctional enzymes consisting of catalytic and regulatory subunits. The regulatory subunit, cyclin, remains dissociated under normal circumstances, and complexation of cyclin with the catalytic subunit of CDK leads to its activation for phosphorylation of protein substrates. The primary role of CDKs is in the regulation of the cell cycle. Retinoblastoma protein (Rb) is one of the widely investigated tumor suppressor protein substrates of CDK, which prevents cells from entering into cell-cycle under normal conditions. Phosphorylation of Rb by CDKs causes its inactivation and ultimately allows cells to enter a new cell cycle. Many cancers are associated with hyperactivation of CDKs as a result of mutation of the CDK genes or CDK inhibitor genes. Therefore, CDK modulators are of great interest to explore as novel therapeutic agents against cancer and led to the discovery of several CDK inhibitors to clinics. This review focuses on the current progress and development of anti-cancer CDK inhibitors from preclinical to clinical and synthetic to natural small molecules.

Pd-Catalyzed double carbopalladation/syn-insertion cascade reactions toward medium-size sulfoximine heterocycles

With the assistance of Ac in sulfoximine as a protecting group (PG) and MeOH as a de-PG agent, Pd-catalyzed multicomponent reactions were developed to access indene-fused medium-size sulfoximine heterocycles. The reactions proceeded smoothly under exceptionally mild conditions to produce polyheterocyclic sulfoximines with regiospecificity and good functional group tolerance. A double carbopalladation/syn-insertion of triple bond sequences was proposed tothis transformation.

One-pot multi-step cascade protocols toward β-indolyl sulfoximidoyl amides via intermolecular trapping of an α-indolylpalladium complex by CO

Various β-indolyl sulfoximidoyl amides were efficiently prepared from ortho-iodoanilines, propargyl bromides, 1 atm of CO, and substituted NH-sulfoximines, through a palladium-catalyzed indole annulation/carbonyl insertion/C-N bond formation cascade. Mostly good to high yields of the products were obtained through this multi-step, one-pot reaction protocol under very gentle reaction conditions. The obtained β-indolyl sulfoximidoyl amides could be converted into biologically interesting sulfoximine analogues that contain a tryptamine moiety.

Dysregulation of Wnt/β-catenin signaling by protein kinases in hepatocellular carcinoma and its therapeutic application

Wnt/β-catenin signaling is indispensable for many biological processes, including embryonic development, cell cycle, inflammation, and carcinogenesis. Aberrant activation of the Wnt/β-catenin signaling can promote tumorigenicity and enhance metastatic potential in hepatocellular carcinoma (HCC). Targeting this pathway is a new opportunity for precise medicine for HCC. However, inhibiting Wnt/β-catenin signaling alone is unlikely to significantly improve HCC patient outcome due to the lack of specific inhibitors and the complexity of this pathway. Combination with other therapies will be an important next step in improving the efficacy of Wnt/β-catenin signaling inhibitors. Protein kinases play a key and evolutionarily conserved role in the Wnt/β-catenin signaling and have become one of the most important drug targets in cancer. Targeting Wnt/β-catenin signaling and its regulatory kinase together will be a promising HCC management strategy. In this review, we summarize the kinases that modulate the Wnt/β-catenin signaling in HCC and briefly discuss their molecular mechanisms. Furthermore, we list some small molecules that target the kinases and may inhibit Wnt/β-catenin signaling, to offer new perspectives for preclinical and clinical HCC studies.

Inhibitors of Cyclin-Dependent Kinases: Types and Their Mechanism of Action

Recent studies on cyclin-dependent kinase (CDK) inhibitors have revealed that small molecule drugs have become very attractive for the treatment of cancer and neurodegenerative disorders. Most CDK inhibitors have been developed to target the ATP binding pocket. However, CDK kinases possess a very similar catalytic domain and three-dimensional structure. These features make it difficult to achieve required selectivity. Therefore, inhibitors which bind outside the ATP binding site present a great interest in the biomedical field, both from the fundamental point of view and for the wide range of their potential applications. This review tries to explain whether the ATP competitive inhibitors are still an option for future research, and highlights alternative approaches to discover more selective and potent small molecule inhibitors.

Autocatalytic photoredox Chan-Lam coupling of free diaryl sulfoximines with arylboronic acids

N-Arylation of NH-sulfoximines represents an appealing approach to access N-aryl sulfoximines, but has not been successfully applied to NH-diaryl sulfoximines. Herein, a copper-catalyzed photoredox dehydrogenative Chan-Lam coupling of free diaryl sulfoximines and arylboronic acids is described. This neutral and ligand-free coupling is initiated by ambient light-induced copper-catalyzed single-electron reduction of NH-sulfoximines. This electron transfer route circumvents the sacrificial oxidant employed in traditional Chan-Lam coupling reactions, increasing the environmental friendliness of this process. Instead, dihydrogen gas forms as a byproduct of this reaction. Mechanistic investigations also reveal a unique autocatalysis process. The C–N coupling products, N-arylated sulfoximines, serve as ligands along with NH-sulfoximine to bind to the copper species, generating the photocatalyst. DFT calculations reveal that both the NH-sulfoximine substrate and the N-aryl product can ligate the copper accounting for the observed autocatalysis. Two energetically viable stepwise pathways were located wherein the copper facilitates hydrogen atom abstraction from the NH-sulfoximine and the ethanol solvent to produce dihydrogen. The protocol described herein represents an appealing alternative strategy to the classic oxidative Chan-Lam reaction, allowing greater substrate generality as well as the elimination of byproduct formation from oxidants.

N-Arylation of NH-diaryl sulfoximines faces synthetic challenges among reported methods. Here, the authors present a mild copper-catalyzed photoredox dehydrogenative Chan-Lam coupling of free diaryl sulfoximines and arylboronic acids via an auto-catalytic process.

Recent progress in development of cyclin-dependent kinase 7 inhibitors for cancer therapy

Introduction: Cyclin-dependent kinase 7 (CDK7) is a part of the CDK-activating kinase family (CAK) which has a key role in the cell cycle and transcriptional regulation. Several lines of evidence suggest that CDK7 is a promising therapeutic target for cancer. CDK7 selective inhibitors such as SY-5609 and CT7001 are in clinical development. Areas covered: We explore the biology of CDK7 and its role in cancer and follow this with an evaluation of the preclinical and clinical progress of CDK7 inhibitors, and their potential in the clinic. We searched PubMed and ClinicalTrials to identify relevant data from the database inception to 14 October 2020. Expert opinion: CDK7 inhibitors are next generation therapeutics for cancer. However, there are still challenges which include selectively, side effects, and drug resistance. Nevertheless, with ongoing clinical development of these inhibitors and greater analysis of their target, CDK7 inhibitors will become a promising approach for treatment of cancer in the near future.

Selective inhibition of CDK4/6: A safe and effective strategy for developing anticancer drugs

The sustained cell proliferation resulting from dysregulation of the cell cycle and activation of cyclin-dependent kinases (CDKs) is a hallmark of cancer. The inhibition of CDKs is a highly promising and attractive strategy for the development of anticancer drugs. In particular, third-generation CDK inhibitors can selectively inhibit CDK4/6 and regulate the cell cycle by suppressing the G1 to S phase transition, exhibiting a perfect balance between anticancer efficacy and general toxicity. To date, three selective CDK4/6 inhibitors have received approval from the U.S. Food and Drug Administration (FDA), and 15 CDK4/6 inhibitors are in clinical trials for the treatment of cancers. In this perspective, we discuss the crucial roles of CDK4/6 in regulating the cell cycle and cancer cells, analyze the rationale for selectively inhibiting CDK4/6 for cancer treatment, review the latest advances in highly selective CDK4/6 inhibitors with different chemical scaffolds, explain the mechanisms associated with CDK4/6 inhibitor resistance and describe solutions to overcome this issue, and briefly introduce proteolysis targeting chimera (PROTAC), a new and revolutionary technique used to degrade CDK4/6.

Development and Therapeutic Potential of NUAKs Inhibitors

NUAK isoforms, NUAK1 (ARK5) and NUAK2 (SNARK), are important members of the AMPK family of protein kinases. They are involved in a broad spectrum of physiological and cellular events, and sometimes their biological roles overlap. NUAK isoform dysregulation is associated with numerous pathological disorders, including neurodegeneration, metastatic cancer, and diabetes. Therefore, they are promising therapeutic targets in metabolic diseases and cancers; consequently, various NUAK-targeted inhibitors have been disclosed. The first part of this review comprises a brief discussion of the homology, expression, structure, and characteristics of NUAK isoforms. The second part focuses on NUAK isoforms' involvement in crucial biological operations, including mechanistic findings, highlighting how their abnormal functioning contributes to disease progression and quality of life. The third part summarizes the key findings and applications of targeting NUAK isoforms for treating multiple cancers and neurodegenerative disorders. The final part systematically presents a critical review and analysis of the literature on NUAK isoform inhibitions through small molecules.

5-Carbonyl-1,3-oxazine-2,4-diones from N-Cyanosulfoximines and Meldrum's Acid Derivatives

At elevated temperatures, N-cyanosulfoximines react with Meldrum's acid derivatives to give sulfoximines with N-bound 5-carbonyl-1,3-oxazine-2,4-dione groups. A representative product was characterized by single-crystal X-ray structure analysis. The product formation involves an unexpected molecular reorientation requiring several sequential bond-forming and -cleaving processes.

Selective Synthesis of N-Cyano Sulfilimines by Dearomatizing Stable Thionium Ions

For the selective synthesis of N-cyano sulfilimines, we have developed a new method based on the soft-soft interaction between thionium ion electrophiles and cyanonitrene nucleophiles. The stable thionium ion was successfully obtained by oxidative dearomatization using phenyliodine (III) diacetate (PIDA) in N,N-dimethylformamide (DMF). The sulfur imination reactions were tolerant to a wide range of functional groups and exhibited high selectivities and excellent yields. The existence of thionium ion intermediates was confirmed by ultraviolet/visible (UV/vis) spectroscopy and ¹H NMR experiments.

General Method for the Asymmetric Synthesis of N-H Sulfoximines via C-S Bond Formation

A versatile method for the synthesis of enantioenriched N-H sulfoximines is reported. The approach stems from the organomagnesium-mediated ring opening of novel cyclic sulfonimidate templates. The reactions proceed in high yield and with excellent stereofidelity with alkyl, aryl, and heteroaryl Grignard reagents. The chiral auxiliary is readily removed from the resultant sulfoximines via an unusual oxidative debenzylation protocol that utilizes molecular oxygen as the terminal oxidant. This provides a general strategy for the synthesis of highly enantioenriched N-H sulfoximines.

Synthesis of NH-Sulfoximines by Using Recyclable Hypervalent Iodine(III) Reagents under Aqueous Micellar Conditions

The synthesis of NH-sulfoximines from sulfides has been first developed under mild conditions in an aqueous solution with surfactant TPGS-750-M as the catalyst at room temperature. In this newly developed process, a simple and convenient recycling strategy to regenerate the indispensable hypervalent iodine(III) is used. The resulting 1,2,3-trifluoro-5-iodobezene can be recovered almost quantitively from the mixture by liquid-liquid extraction and then oxidized to give the corresponding iodine(III) species. This optimized procedure is compatible with a broad range of functional groups and can be easily performed on a gram scale, providing a green protocol for the synthesis of sulfoximines.

CDK5 Inhibitor Downregulates Mcl-1 and Sensitizes Pancreatic Cancer Cell Lines to Navitoclax

Developing small molecules that indirectly regulate Mcl-1 function has attracted a lot of attention in recent years. Here, we report the discovery of an aminopyrazole, 2-([1,1′-biphenyl]-4-yl)-N-(5-cyclobutyl-1H-pyrazol-3-yl)acetamide (analog 24), which selectively inhibited cyclin-dependent kinase (CDK) 5 over CDK2 in cancer cell lines. We also show that analog 24 reduced Mcl-1 levels in a concentration-dependent manner in cancer cell lines. Using a panel of doxycycline inducible cell lines, we show that CDK5 inhibitor 24 selectively modulates Mcl-1 function while the CDK4/6 inhibitor 6-acetyl-8-cyclopentyl-5-methyl-2-(5-(piperazin-1-yl)pyridin-2-ylamino)pyrido[2,3-day]pyrimidin-7(8H)-one does not. Previous studies using RNA interference and CRISPR showed that concurrent elimination of Bcl-xL and Mcl-1 resulted in induction of apoptosis. In pancreatic cancer cell lines, we show that either CDK5 knockdown or expression of a dominant negative CDK5 when combined with Bcl2 inhibitor results in synergistic induction of apoptosis. Moreover, concurrent pharmacological perturbation of Mcl-1 and Bcl-xL in pancreatic cancer cell lines using a CDK5 inhibitor analog 24 that reduced Mcl-1 levels and 4-(4-{[2-(4-chlorophenyl)-5,5-dimethyl-1-cyclohexen-1-yl]methyl}-1-piperazinyl)-N-[(4-{[(2R)-4-(4-morpholinyl)-1-(phenylsulfanyl)-2-butanyl]amino}-3-[(trifluoromethyl)sulfonyl]phenyl)sulfonyl] benzamide (navitoclax), a Bcl-2/Bcl-xL/Bcl-w inhibitor, resulted in synergistic inhibition of cell growth and induction of apoptosis. In conclusion, we demonstrate targeting CDK5 will sensitize pancreatic cancers to Bcl-2 inhibitors.

Design, Synthesis and Antiplasmodial Evaluation of Sulfoximine-triazole Hybrids as Potential Antimalarial Prototypes

Background:

Malaria, caused by the deadly Plasmodium falciparum strain, claims the lives of millions of people annually. The emergence of drug-resistant strains of P. falciparum to the artemisinin-based combination therapy (ACT), the last line of defense against malaria, is worrisome and urges for the development of new chemo-types with a new mode of action. In the search of new antimalarial agents, hybrids of triazoles and other known antimalarial drugs have been reported to possess better activity than either of the parent compounds administered individually. Despite their better activity, no hybrid antimalarial drugs have been developed so far.

Objective:

In the hope of developing new antimalarial prototypes, we propose the design, synthesis and antimalarial evaluation of novel sulfoximine-triazole hybrids owing to their interesting biological and physiological properties.

Methods:

The sulfoximine part of the hybrid will be synthesized via imidation of the corresponding sulfoxide. Propargylation of the NH moiety of the sulfoximine followed by copper-catalyzed click chemistry with benzyl azide was envisaged to provide the target sulfoximine-triazole hybrids.

Results:

Five novel sulfoximine-triazole hybrids possessing various substituents on the sulfoximine moiety have been successfully synthesized and evaluated for their antiplasmodial and cytotoxicity activities. The results revealed that the co-presence of the sulfoximine and triazole moieties along with a lipophilic alkyl substituent on the sulfur atom impart significant activity.

Conclusion:

Sulfoximine-triazole hybrids could be used as a prototype for the synthesis of new derivatives with better antiplasmodial activities.

Cyclin dependent kinase (CDK) inhibitors as anticancer drugs: Recent advances (2015-2019)

Sustained proliferative capacity and gene dysregulation are hallmarks of cancer. In mammalian cells, cyclin-dependent kinases (CDKs) control critical cell cycle checkpoints and key transcriptional events in response to extracellular and intracellular signals leading to proliferation. Significant clinical activity for the treatment of hormone receptor positive metastatic breast cancer has been demonstrated by palbociclib, ribociclib and abemaciclib, dual CDK4/6 inhibitors recently FDA-approved. SY-1365, a CDK7 inhibitor has shown initial encouraging data in phase I for solid tumors treatment. These results have rejuvenated the CDKs research field. This review provides an overview of relevant advances on CDK inhibitor research since 2015 to 2019, with special emphasis on transcriptional CDK inhibitors, new emerging strategies such as target protein degradation and compounds under clinical evaluation.