Discovery of the macrocycle 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene (SB1518), a potent Janus kinase 2/fms-like tyrosine kinase-3 (JAK2/FLT3) inhibitor for the treatment of myelofibrosis and lymphoma

A comprehensive review of new small molecule drugs approved by the FDA in 2022: Advance and prospect

In 2022, the U.S. Food and Drug Administration approved a total of 16 marketing applications for small molecule drugs, which not only provided dominant scaffolds but also introduced novel mechanisms of action and clinical indications. The successful cases provide valuable information for optimizing efficacy and enhancing pharmacokinetic properties through strategies like macrocyclization, bioequivalent group utilization, prodrug synthesis, and conformation restriction. Therefore, gaining an in-depth understanding of the design principles and strategies underlying these drugs will greatly facilitate the development of new therapeutic agents. This review focuses on the research and development process of these newly approved small molecule drugs including drug design, structural modification, and improvement of pharmacokinetic properties to inspire future research in this field.

Macrocyclic-based strategy in drug design: From lab to the clinic

Macrocyclic compounds have emerged as potent tools in the field of drug design, offering unique advantages for enhancing molecular recognition, improving pharmacokinetic properties, and expanding the chemical space accessible to medicinal chemists. This review delves into the evolutionary trajectory of macrocyclic-based strategies, tracing their journey from laboratory innovations to clinical applications. Beginning with an exploration of the defining structural features of macrocycles and their impact on drug-like characteristics, this discussion progresses to highlight key design principles that have facilitated the development of diverse macrocyclic drug candidates. Through a series of illustrative representative case studies from approved macrocyclic drugs and candidates spanning various therapeutic areas, particular emphasis is placed on their efficacy in targeting challenging protein-protein interactions, enzymes, and receptors. Additionally, this review thoroughly examines how macrocycles effectively address critical issues such as metabolic stability, oral bioavailability and selectivity. Valuable insights into optimization strategies employed during both approved and clinical phases underscore successful translation of promising leads into efficacious therapies while providing valuable perspectives on harnessing the full potential of macrocycles in drug discovery and development endeavors.

Quantitative MRI reveals heterogeneous impacts of treatment on diseased bone marrow in a mouse model of myelofibrosis

PURPOSE

Analyzing bone marrow in the hematologic cancer myelofibrosis requires endpoint histology in mouse models and bone marrow biopsies in patients. These methods hinder the ability to monitor therapy over time. Preclinical studies typically begin treatment before mice develop myelofibrosis, unlike patients who begin therapy only after onset of disease. Using clinically relevant, quantitative MRI metrics allowed us to evaluate treatment in mice with established myelofibrosis.

METHODS

We used chemical shift-encoded fat imaging, DWI, and magnetization transfer sequences to quantify bone marrow fat, cellularity, and macromolecular components in a mouse model of myelofibrosis. We monitored spleen volume, the established imaging marker for treatment, with anatomic MRI. After confirming bone marrow disease by MRI, we randomized mice to treatment with an approved drug (ruxolitinib or fedratinib) or an investigational agent, navitoclax, for 33 days. We measured the effects of therapy over time with bone marrow and spleen MRI.

RESULTS

All treatments produced heterogeneous responses with improvements in bone marrow evident in subsets of individual mice in all treatment groups. Reductions in spleen volume commonly occurred without corresponding improvement in bone marrow. MRI revealed patterns associated with effective and ineffective responses to treatment in bone marrow and identified regional variations in efficacy within a bone.

CONCLUSIONS

Quantitative MRI revealed modest, heterogeneous improvements in bone marrow disease when treating mice with established myelofibrosis. These results emphasize the value of bone marrow MRI to assess treatment in preclinical models and the potential to advance clinical trials for patients.

Tumor biomarkers for diagnosis, prognosis and targeted therapy

Tumor biomarkers, the substances which are produced by tumors or the body's responses to tumors during tumorigenesis and progression, have been demonstrated to possess critical and encouraging value in screening and early diagnosis, prognosis prediction, recurrence detection, and therapeutic efficacy monitoring of cancers. Over the past decades, continuous progress has been made in exploring and discovering novel, sensitive, specific, and accurate tumor biomarkers, which has significantly promoted personalized medicine and improved the outcomes of cancer patients, especially advances in molecular biology technologies developed for the detection of tumor biomarkers. Herein, we summarize the discovery and development of tumor biomarkers, including the history of tumor biomarkers, the conventional and innovative technologies used for biomarker discovery and detection, the classification of tumor biomarkers based on tissue origins, and the application of tumor biomarkers in clinical cancer management. In particular, we highlight the recent advancements in biomarker-based anticancer-targeted therapies which are emerging as breakthroughs and promising cancer therapeutic strategies. We also discuss limitations and challenges that need to be addressed and provide insights and perspectives to turn challenges into opportunities in this field. Collectively, the discovery and application of multiple tumor biomarkers emphasized in this review may provide guidance on improved precision medicine, broaden horizons in future research directions, and expedite the clinical classification of cancer patients according to their molecular biomarkers rather than organs of origin.

Macrocycles and macrocyclization in anticancer drug discovery: Important pieces of the puzzle

Increasing disease-related proteins have been identified as novel therapeutic targets. Macrocycles are emerging as potential solutions, bridging the gap between conventional small molecules and biomacromolecules in drug discovery. Inspired by successful macrocyclic drugs of natural origins, macrocycles are attracting more attention for enhanced binding affinity and target selectivity. Due to the conformation constraint and structure preorganization, macrocycles can reach bioactive conformations more easily than parent acyclic compounds. Also, rational macrocyclization combined with sequent structural modification will help improve oral bioavailability and combat drug resistance. This review introduces various strategies to enhance membrane permeability in macrocyclization and subsequent modification, such as N-methylation, intramolecular hydrogen bonding modulation, isomerization, and reversible bicyclization. Several case studies highlight macrocyclic inhibitors targeting kinases, HDAC, and protein-protein interactions. Finally, some macrocyclic agents targeting tumor microenvironments are illustrated.

Kinase inhibitor macrocycles: a perspective on limiting conformational flexibility when targeting the kinome with small molecules

Methods utilized for drug discovery and development within the kinome have rapidly evolved since the approval of imatinib, the first small molecule kinase inhibitor. Macrocycles have received increasing interest as a technique to improve kinase inhibitor drug properties evident by the FDA approvals of lorlatinib, pacritinib, and repotrectinib. Compared to their acyclic counterparts, macrocycles can possess improved pharmacodynamic and pharmacokinetic properties. This review highlights clinical success stories when implementing macrocycles in kinase-based drug discovery and showcases that macrocyclization is a clinically validated drug discovery strategy when targeting the kinome.

Targeting JAK2/STAT3 for the treatment of cancer: A review on recent advancements in molecular development using structural analysis and SAR investigations

Cancer is indeed considered a hazardous and potentially life-threatening disorder. The JAK/STAT pathway is an important intracellular signaling cascade essential for many physiological functions, such as immune response, cell proliferation, and differentiation. Dysregulation of this pathway aids in the progression and development of cancer. The downstream JAK2/STAT3 signaling cascades are legitimate targets against which newer anticancer drugs can be developed to prevent and treat cancer. Understanding the mechanisms behind JAK2/STAT3 participation in cancer has paved the way for developing innovative targeted medicines with the potential to improve cancer treatment outcomes. This article provides information on the current scenario and recent advancements in the design and development of anticancer drugs targeting JAK2/STAT3, including structural analysis and SAR investigations of synthesized molecules. Numerous preclinical and clinical trials are ongoing on these inhibitors, which are highlighted to gain more insight into the broader development prospects of inhibitors of JAK2/STAT3.

Medicinal chemistry perspective of JAK inhibitors: synthesis, biological profile, selectivity, and structure activity relationship

JAK-STAT signalling pathway was discovered more than quarter century ago. The JAK-STAT pathway protein is considered as one of the crucial hubs for cytokine secretion which mediates activation of different inflammatory, cellular responses and hence involved in different etiological factors. The various etiological factors involved are haematopoiesis, immune fitness, tissue repair, inflammation, apoptosis, and adipogenesis. The presence of the active mutation V617K plays a significant role in the progression of the JAK-STAT pathway-related disease. Consequently, targeting the JAK-STAT pathway could be a promising therapeutic approach for addressing a range of causative factors. In this current review, we provided a comprehensive discussion for the in-detail study of anatomy and physiology of the JAK-STAT pathway which contributes structural domain rearrangement, activation, and negative regulation associated with the downstream signaling pathway, relationship between different cytokines and diseases. This review also discussed the recent development of clinical trial entities. Additionally, this review also provides updates on FDA-approved drugs. In the current investigation, we have classified recently developed small molecule inhibitors of JAK-STAT pathway according to different chemical classes and we emphasized their synthetic routes, biological evaluation, selectivity, and structure-activity relationship.

Exploring the synthetic approaches and clinical prowess of established macrocyclic pharmaceuticals

Macrocyclic compounds, characterized by cyclic structures, often originate from either modified forms of unicyclic canonical molecules or natural products. Within the field of medicinal chemistry, there has been a growing fascination with drug-like macrocycles in recent years, primarily due to compelling evidence indicating that macrocyclization can significantly influence both the biological and physiochemical properties, as well as the selectivity, when compared to their acyclic counterparts. The approval of contemporary pharmaceutical agents like Lorlatinib underscore the notable clinical relevance of drug-like macrocycles. Nonetheless, the synthesis of these drug-like macrocycles poses substantial challenges, primarily stemming from the complexity of ring-closing reactions, which are inherently dependent on the size and geometry of the bridging linker, impacting overall yields. Nevertheless, macrocycles offer a promising avenue for expanding the synthetic toolkit in medicinal chemistry, enabling the creation of bioactive compounds. To shed light on the subject, we delve into the clinical prowess of established macrocyclic drugs, spanning various therapeutic areas, including oncology, and infectious diseases. Case studies of clinically approved macrocyclic agents illustrate their profound impact on patient care and disease management. As we embark on this journey through the world of macrocyclic pharmaceuticals, we aim to provide a comprehensive overview of their synthesis and clinical applications, shedding light on the pivotal role they play in modern medicine.

Structure-property Relationships Reported for the New Drugs Approved in 2022

BACKGROUND

The structure-property relationship illustrates how modifying the chemical structure of a pharmaceutical compound influences its absorption, distribution, metabolism, excretion, and other related properties. Understanding structure-property relationships of clinically approved drugs could provide useful information for drug design and optimization strategies.

METHOD

Among new drugs approved around the world in 2022, including 37 in the US, structure- property relationships of seven drugs were compiled from medicinal chemistry literature, in which detailed pharmacokinetic and/or physicochemical properties were disclosed not only for the final drug but also for its key analogues generated during drug development.

RESULTS

The discovery campaigns for these seven drugs demonstrate extensive design and optimization efforts to identify suitable candidates for clinical development. Several strategies have been successfully employed, such as attaching a solubilizing group, bioisosteric replacement, and deuterium incorporation, resulting in new compounds with enhanced physicochemical and pharmacokinetic properties.

CONCLUSION

The structure-property relationships hereby summarized illustrate how proper structural modifications could successfully improve the overall drug-like properties. The structure-property relationships of clinically approved drugs are expected to continue to provide valuable references and guides for the development of future drugs.

Synthesis and clinical application of small-molecule inhibitors of Janus kinase

Janus kinase (JAK) plays a crucial role in intracellular signaling pathways, particularly in cytokine-mediated signal transduction, making them attractive therapeutic targets for a wide range of diseases, including autoimmune disorders, myeloproliferative neoplasms, and inflammatory conditions. The review provides a comprehensive overview of the development and therapeutic potential of small-molecule inhibitors targeting JAK family of proteins in various clinical trials. It also discusses the mechanisms of action, specificity, and selectivity of these inhibitors, shedding light on the challenges associated with achieving target selectivity while minimizing off-target effects. Moreover, the review offers insights into the clinical applications of JAK inhibitors, summarizing the ongoing clinical trials and the Food and Drug Administration (FDA)-approved JAK inhibitors currently available for various diseases. Overall, this review provides a thorough examination of the synthesis and clinical use of typical small-molecule JAK inhibitors in different clinical stages and offers a bright future for the development of novel small-molecule JAK inhibitors.

Identification of HHT-9041P1: A novel potent and selective JAK1 inhibitor in a rat model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic disease associated with long-term disability and premature mortality. If left untreated, it can seriously affect patients' quality of life. The JAK-STAT signal transduction process is known to affect the occurrence and development of RA, and small molecule JAK inhibitors, such as tofacitinib, have been identified as treatments for RA. However, tofacitinib is a non-selective JAK inhibitor that was found to be associated with dose-limiting tolerability and safety issues, such as anemia in phase 2 dose-ranging studies. Therefore, we developed a selective JAK1 inhibitor, HHT-9041P1, to overcome target-related adverse reactions. We used enzyme and cytokine potency assays in vitro as well as the collagen-induced arthritis (CIA) model in vivo to explore the efficacy and mechanism. In vitro, HHT-9041P1 was diluted (0.017 nM-1 mM) in DMSO) and mixed with JAK1, JAK2, JAK3 or TYK2 kinases for use in the respective assays for inhibitory activity and selectivity evaluation. Fresh human PBMCs were activated and incubated with 100 ng/mL cytokine IL-6 or 20 ng/mL GM-CSF for use in the investigation of the immune mechanism. In vivo, HHT-9041P1 (1 mg/kg, 3 mg/kg and 10 mg/kg) was administered by oral gavage twice daily to CIA model Lewis rats from Day 8 to Day 29 for paw swelling and arthritis score evaluation. At the end of the experiment, the rats were sacrificed before collection of the hind ankle joint, spleen and blood for analysis of inflammation, arthritis phenotypes, inflammatory cytokine expression and Th1 cell proportions. As expected, HHT-9041P1 showed 10-fold greater selectivity for JAK1 over JAK2, and 23-fold greater selectivity over JAK3 in cellular assays. The high selectivity of HHT-9041P1 was also validated by in vivo safety studies. HHT-9041P1 demonstrated significant efficacy in a rat model of collagen-induced arthritis (CIA) and was associated with reduced helper T Cell 1 (Th1) cell differentiation. HHT-9041P1 also exhibited excellent pharmacokinetics properties. Thus, HHT-9041P1 was identified as a candidate for clinical development with many options for the treatment of RA.

New drug approvals for 2022: Synthesis and clinical applications

The U.S. Food and Drug Administration has approved a total of 37 new drugs in 2022, which are composed of 20 chemical entities and 17 biologics. In particular, 20 chemical entities, including 17 small molecule drugs, 1 radiotherapy, and 2 diagnostic agents, provide privileged scaffolds, breakthrough clinical benefits, and a new mechanism of action for the discovery of more potent clinical candidates. The structure-based drug development with clear targets and fragment-based drug development with privileged scaffolds have always been the important modules in the field of drug discovery, which could easily bypass the patent protection and bring about improved biological activity. Therefore, we summarized the relevant valuable information about clinical application, mechanism of action, and chemical synthesis of 17 newly approved small molecule drugs in 2022. We hope this timely and comprehensive review could bring about creative and elegant inspiration on the synthetic methodologies and mechanism of action for the discovery of new drugs with novel chemical scaffolds and extended clinical indications.

Precision Oncology Comes of Age: Designing Best-in-Class Small Molecules by Integrating Two Decades of Advances in Chemistry, Target Biology, and Data Science

Small-molecule drugs have enabled the practice of precision oncology for genetically defined patient populations since the first approval of imatinib in 2001. Scientific and technology advances over this 20-year period have driven the evolution of cancer biology, medicinal chemistry, and data science. Collectively, these advances provide tools to more consistently design best-in-class small-molecule drugs against known, previously undruggable, and novel cancer targets. The integration of these tools and their customization in the hands of skilled drug hunters will be necessary to enable the discovery of transformational therapies for patients across a wider spectrum of cancers.

SIGNIFICANCE

Target-centric small-molecule drug discovery necessitates the consideration of multiple approaches to identify chemical matter that can be optimized into drug candidates. To do this successfully and consistently, drug hunters require a comprehensive toolbox to avoid following the "law of instrument" or Maslow's hammer concept where only one tool is applied regardless of the requirements of the task. Combining our ever-increasing understanding of cancer and cancer targets with the technological advances in drug discovery described below will accelerate the next generation of small-molecule drugs in oncology.

An Updated Review on Developing Small Molecule Kinase Inhibitors Using Computer-Aided Drug Design Approaches

Small molecule kinase inhibitors (SMKIs) are of heightened interest in the field of drug research and development. There are 79 (as of July 2023) small molecule kinase inhibitors that have been approved by the FDA and hundreds of kinase inhibitor candidates in clinical trials that have shed light on the treatment of some major diseases. As an important strategy in drug design, computer-aided drug design (CADD) plays an indispensable role in the discovery of SMKIs. CADD methods such as docking, molecular dynamic, quantum mechanics/molecular mechanics, pharmacophore, virtual screening, and quantitative structure-activity relationship have been applied to the design and optimization of small molecule kinase inhibitors. In this review, we provide an overview of recent advances in CADD and SMKIs and the application of CADD in the discovery of SMKIs.

Synthesis and clinical application of new drugs approved by FDA in 2022

The pharmaceutical industry had a glorious year in 2022, with a total of 37 new drugs including 20 new chemical entities (NCEs) and 17 new biological entities (NBEs) approved by the Food and Drug Administration (FDA). These drugs are mainly concentrated in oncology, central nervous system, antiinfection, hematology, cardiomyopathy, dermatology, digestive system, ophthalmology, MRI enhancer and other therapeutic fields. Of the 37 drugs, 25 (68%) were approved through an expedited review pathway, and 19 (51%) were approved to treat rare diseases. These newly listed drugs have unique structures and new mechanisms of action, which can serve as lead compounds for designing new drugs with similar biological targets and enhancing therapeutic efficacy. This review aims to outline the clinical applications and synthetic methods of 19 NCEs newly approved by the FDA in 2022, but excludes contrast agent (Xenon Xe-129). We believe that an in-depth understanding of the synthetic methods of drug molecules will provide innovative and practical inspiration for the development of new, more effective, and practical synthetic techniques. According to the therapeutic areas of these 2022 FDA-approved drugs, we have classified these 19 NCEs into seven categories and will introduce them in the order of their approval for marketing.

Next-Generation JAK2 Inhibitors for the Treatment of Myeloproliferative Neoplasms: Lessons from Structure-Based Drug Discovery Approaches

Selective inhibitors of Janus kinase (JAK) 2 have been in demand since the discovery of the JAK2 V617F mutation present in patients with myeloproliferative neoplasms (MPN); however, the structural basis of V617F oncogenicity has only recently been elucidated. New structural studies reveal a role for other JAK2 domains, beyond the kinase domain, that contribute to pathogenic signaling. Here we evaluate the structure-based approaches that led to recently-approved type I JAK2 inhibitors (fedratinib and pacritinib), as well as type II (BBT594 and CHZ868) and pseudokinase inhibitors under development (JNJ7706621). With full-length JAK homodimeric structures now available, superior selective and mutation-specific JAK2 inhibitors are foreseeable.

SIGNIFICANCE

The JAK inhibitors currently used for the treatment of MPNs are effective for symptom management but not for disease eradication, primarily because they are not strongly selective for the mutant clone. The rise of computational and structure-based drug discovery approaches together with the knowledge of full-length JAK dimer complexes provides a unique opportunity to develop better targeted therapies for a range of conditions driven by pathologic JAK2 signaling.

Instant Macrocyclizations via Multicomponent Reactions

Macrocycles fascinate chemists due to both their structure and their applications. However, we still lack efficient and sustainable synthetic methods, giving us straightforward access to them. Herein, a rapid macrocyclization utilizing a two-step, one-pot approach based on orthogonal multicomponent reaction (MCR) tactics is introduced. This synthetic protocol, which is based on Ugi and Groebke-Blackburn-Bienaymé reactions with isocyanides tethered to alkyl tosylates, yields medium sized macrocycles that are otherwise difficult to achieve. Single crystal structures reveal conformational reorganization via intramolecular hydrogen bonding, and modeling studies profile the synthesized libraries.

Rigid Scaffolds Are Promising for Designing Macrocyclic Kinase Inhibitors

Macrocyclic kinase inhibitors (MKIs) are gaining attention due to their favorable selectivity and potential to overcome drug resistance, yet they remain challenging to design because of their novel structures. To facilitate the design and discovery of MKIs, we investigate MKI rational design starting from initial acyclic compounds by performing microsecond-scale atomistic simulations for multiple MKIs, constructing an MKI database, and analyzing MKIs using hierarchical cluster analysis. Our studies demonstrate that the binding modes of MKIs are like those of their corresponding acyclic counterparts against the same kinase targets. Importantly, within the respective binding sites, the MKI scaffolds retain the same conformations as their corresponding acyclic counterparts, demonstrating the rigidity of scaffolds before and after molecular cyclization. The MKI database includes 641 nanomole-level MKIs from 56 human kinases elucidating the features of rigid scaffolds and the core structures of MKIs. Collectively these results and resources can facilitate MKI development.

Macrocyclization of linear molecules by deep learning to facilitate macrocyclic drug candidates discovery

Interest in macrocycles as potential therapeutic agents has increased rapidly. Macrocyclization of bioactive acyclic molecules provides a potential avenue to yield novel chemical scaffolds, which can contribute to the improvement of the biological activity and physicochemical properties of these molecules. In this study, we propose a computational macrocyclization method based on Transformer architecture (which we name Macformer). Leveraging deep learning, Macformer explores the vast chemical space of macrocyclic analogues of a given acyclic molecule by adding diverse linkers compatible with the acyclic molecule. Macformer can efficiently learn the implicit relationships between acyclic and macrocyclic structures represented as SMILES strings and generate plenty of macrocycles with chemical diversity and structural novelty. In data augmentation scenarios using both internal ChEMBL and external ZINC test datasets, Macformer display excellent performance and generalisability. We showcase the utility of Macformer when combined with molecular docking simulations and wet lab based experimental validation, by applying it to the prospective design of macrocyclic JAK2 inhibitors.

Synthesis of a DNA-Encoded Macrocyclic Library Utilizing Intramolecular Benzimidazole Formation

Macrocycles occupy chemical space "beyond the rule of five". They bridge traditional bioactive small molecule drugs and macromolecules and have the potential to modulate challenging targets such as PPI or proteases. Here we report an on-DNA macrocyclization reaction utilizing intramolecular benzimidazole formation. A 129-million-member macrocyclic library composed of a privileged benzimidazole core, a dipeptide sequence (natural or non-natural), and linkers of varying length and flexibility was designed and synthesized.

IRAK1 inhibition blocks the HIV-1 RNA mediated pro-inflammatory cytokine response from microglia

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) are a common source of morbidity in people living with HIV (PLWH). Although antiretroviral therapy (ART) has lessened the severity of neurocognitive disorders, cognitive impairment still occurs in PLWH receiving ART. The pathogenesis of HAND is likely multifaceted, but common factors include the persistence of HIV transcription within the central nervous system, higher levels of pro-inflammatory cytokines in the cerebrospinal fluid, and the presence of activated microglia. Toll-like receptor (TLR) 7 and TLR8 are innate pathogen recognition receptors located in microglia and other immune and non-immune cells that can recognise HIV RNA and trigger pro-inflammatory responses. IL-1 receptor-associated kinase (IRAK) 1 is key to these signalling pathways. Here, we show that IRAK1 inhibition inhibits the TLR7 and TLR8-dependent pro-inflammatory response to HIV RNA. Using genetic and pharmacological inhibition, we demonstrate that inhibition of IRAK1 prevents IRAK1 phosphorylation and ubiquitination, and the subsequent recruitment of TRAF6 and the TAK1 complex to IRAK1, resulting in the inhibition of downstream signalling and the suppression of pro-inflammatory cytokine and chemokine release.

CoGT: Ensemble Machine Learning Method and Its Application on JAK Inhibitor Discovery

The discovery of new drug candidates to inhibit an intended target is a complex and resource-consuming process. A machine learning (ML) method for predicting drug-target interactions (DTI) is a potential solution to improve the efficiency. However, traditional ML approaches have limitations in accuracy. In this study, we developed a novel ensemble model CoGT for DTI prediction using multilayer perceptron (MLP), which integrated graph-based models to extract non-Euclidean molecular structures and large pretrained models, specifically chemBERTa, to process simplified molecular input line entry systems (SMILES). The performance of CoGT was evaluated using compounds inhibiting four Janus kinases (JAKs). Results showed that the large pretrained model, chemBERTa, was better than other conventional ML models in predicting DTI across multiple evaluation metrics, while the graph neural network (GNN) was effective for prediction on imbalanced data sets. To take full advantage of the strengths of these different models, we developed an ensemble model, CoGT, which outperformed other individual ML models in predicting compounds' inhibition on different isoforms of JAKs. Our data suggest that the ensemble model CoGT has the potential to accelerate the process of drug discovery.

Accelerated Discovery of Macrocyclic CDK2 Inhibitor QR-6401 by Generative Models and Structure-Based Drug Design

Selective CDK2 inhibitors have the potential to provide effective therapeutics for CDK2-dependent cancers and for combating drug resistance due to high cyclin E1 (CCNE1) expression intrinsically or CCNE1 amplification induced by treatment of CDK4/6 inhibitors. Generative models that take advantage of deep learning are being increasingly integrated into early drug discovery for hit identification and lead optimization. Here we report the discovery of a highly potent and selective macrocyclic CDK2 inhibitor QR-6401 (23) accelerated by the application of generative models and structure-based drug design (SBDD). QR-6401 (23) demonstrated robust antitumor efficacy in an OVCAR3 ovarian cancer xenograft model via oral administration.

2-Aminopyrimidine derivatives as selective dual inhibitors of JAK2 and FLT3 for the treatment of acute myeloid leukemia

Dual inhibitors of JAK2 and FLT3 can synergistically control the development of acute myeloid leukemia (AML), and overcome secondary drug resistance of AML that is associated with FLT3 inhibition. We therefore designed and synthesized a series of 4-piperazinyl-2-aminopyrimidines as dual inhibitors of JAK2 and FLT3, and improved their selectivity for JAK2. Screening cascades revealed that compound 11r exhibited inhibitory activity with IC₅₀ values of 2.01, 0.51, and 104.40 nM against JAK2, FLT3, and JAK3, respectively. Compound 11r achieved a high selectivity for JAK2 at a ratio of 51.94, and also showed potent antiproliferative activity in HEL (IC₅₀ = 1.10 μM) and MV4-11 (IC₅₀ = 9.43 nM) cell lines. In an in vitro metabolism assay, 11r exhibited moderate stability in human liver microsomes (HLMs), with a half-life time of 44.4 min, and in rat liver microsomes (RLMs), with a half-life of 143 min. In pharmacokinetic studies, compound 11r showed moderate absorption (Tmax = 5.33 h), with a peak concentration of 38.7 ng/mL and an AUC of 522 ng h/mL in rats, and an oral bioavailability of 25.2%. In addition, 11r induced MV4-11 cell apoptosis in a dose-dependent manner. These results indicate that 11r is a promising selective JAK2/FLT3 dual inhibitor.

Pacritinib inhibits glucose consumption in squamous cell lung cancer cells by targeting FLT3

Squamous cell lung cancer maintains its growth through elevated glucose consumption, but selective glucose consumption inhibitors are lacking. Here, we discovered using a high-throughput screen new compounds that block glucose consumption in three squamous cell lung cancer cell lines and identified 79 compounds that block glucose consumption in one or more of these cell lines. Based on its ability to block glucose consumption in all three cell lines, pacritinib, an inhibitor of FMS Related Receptor Tyrosine Kinase 3 (FLT3) and Janus Kinase 2 (JAK2), was further studied. Pacritinib decreased glucose consumption in squamous cell lung cancer cells in cell culture and in vivo without affecting glucose consumption in healthy tissues. Pacritinib blocked hexokinase activity, and Hexokinase 1 and 2 mRNA and protein expression. Overexpression of Hexokinase 1 blocked the ability of pacritinib to inhibit glucose consumption in squamous cell lung cancer cells. Overexpression of FLT3 but not JAK2 significantly increased glucose consumption and blocked the ability of pacritinib to inhibit glucose consumption in squamous cell lung cancer cells. Additional FLT3 inhibitors blocked glucose consumption in squamous cell lung cancer cells. Our study identifies FLT3 inhibitors as a new class of inhibitors that can block glucose consumption in squamous cell lung cancer.

Therapeutic implications of current Janus kinase inhibitors as anti-COVID agents: A review

Severe cases of COVID-19 are characterized by hyperinflammation induced by cytokine storm, ARDS leading to multiorgan failure and death. JAK-STAT signaling has been implicated in immunopathogenesis of COVID-19 infection under different stages such as viral entry, escaping innate immunity, replication, and subsequent inflammatory processes. Prompted by this fact and prior utilization as an immunomodulatory agent for several autoimmune, allergic, and inflammatory conditions, Jakinibs have been recognized as validated small molecules targeting the rapid release of proinflammatory cytokines, primarily IL-6, and GM-CSF. Various clinical trials are under investigation to evaluate Jakinibs as potential candidates for treating COVID-19. Till date, there is only one small molecule Jakinib known as baricitinib has received FDA-approval as a standalone immunomodulatory agent in treating critical COVID-19 patients. Though various meta-analyses have confirmed and validated the safety and efficacy of Jakinibs, further studies are required to understand the elaborated pathogenesis of COVID-19, duration of Jakinib treatment, and assess the combination therapeutic strategies. In this review, we highlighted JAK-STAT signalling in the pathogenesis of COVID-19 and clinically approved Jakinibs. Moreover, this review described substantially the promising use of Jakinibs and discussed their limitations in the context of COVID-19 therapy. Hence, this review article provides a concise, yet significant insight into the therapeutic implications of Jakinibs as potential anti-COVID agents which opens up a new horizon in the treatment of COVID-19, effectively.

FDA-Approved Small Molecules in 2022: Clinical Uses and Their Synthesis

This review describes the recently FDA-approved drugs (in the year 2022). Many of these products contain active moieties that FDA had not previously approved, either as a single ingredient or as part of a combination. These products frequently provide important new therapies for patients with multiple unmet diseases. The diverse small molecules are described according to the date of approval and their syntheses is discussed. This review comprises classical chemical scaffolds together with innovative drugs such as a deuterium-containing drug.

The odyssey of pacritinib in myelofibrosis

Myelofibrosis (MF) can present with symptomatic splenomegaly and/or cytopenias including thrombocytopenia. Disease-related thrombocytopenia is a poor prognostic factor with a median overall survival of less than 2 years. Currently approved JAK1/2 inhibitors have not been evaluated in patients with platelets ≤ 50 × 109/L and in fact could potentiate thrombocytopenia because of their combined JAK1/2 inhibitory activity. Pacritinib (PAC), a selective JAK2, fms-like tyrosine kinase 3, interleukin-1 receptor-associated kinase 1 multikinase inhibitor was developed to meet this unmet need. PAC was evaluated in 2 randomized phase 3 trials in the frontline setting (PERSIST-1, PAC 400 mg daily vs best available therapy) and second-line setting in patients with MF with platelets ≤ 100 × 109/L (PERSIST-2, PAC 400 mg daily or 200 mg twice daily vs best available therapy). PERSIST-1 met its primary end point; however, the development of PAC hit a brief pause because of a US Food and Drug Administration-mandated clinical hold for excess of bleeding and cardiac events in the PAC 400 mg daily arm in the PERSIST-1 study. Although the PERSIST-2 study was terminated abruptly because of this clinical hold, it met its splenic response end point and demonstrated a trend toward symptom improvement. Subsequent, diligent review of the PERSIST-1 and PERSIST-2 studies did not confirm an excess of severe bleeding or cardiac events on the PAC arm. Additionally, the dose finding PAC203 study endorsed the safety and efficacy of 200 mg twice daily, leading to the approval of PAC for the treatment of patients with MF with platelets ≤ 50 × 109/L.

FLT3 inhibitors for acute myeloid leukemia: successes, defeats, and emerging paradigms

FLT3 mutations are one of the most common genetic aberrations found in nearly 30% of acute myeloid leukemias (AML). The mutations are associated with poor prognosis despite advances in the understanding of the biological mechanisms of AML. Numerous small molecule FLT3 inhibitors have been developed in an effort to combat AML. Even with the development of these inhibitors, the five-year overall survival for newly diagnosed AML is less than 30%. In 2017, midostaurin received FDA approval to treat AML, which was the first approved FLT3 inhibitor in the U.S. and Europe. Following, gilteritinib received FDA approval in 2018 and in 2019 quizartinib received approval in Japan. This review parallels these clinical success stories along with other pre-clinical and clinical investigations of FLT3 inhibitors.

Pacritinib Inhibition of IRAK1 Blocks Aberrant TLR8 Signalling by SARS-CoV-2 and HIV-1-Derived RNA

Macrophages promote an early host response to infection by releasing pro-inflammatory cytokines such as interleukin (IL) 1β (IL-1β), tumour necrosis factor (TNF), and IL-6. One of the mechanisms through which cells sense pathogenic microorganisms is through Toll-like receptors (TLRs). IL-1 receptor-associated kinase (IRAK) 1, IRAK2, IRAK3, and IRAK4 are integral to TLR and IL-1 receptor signalling pathways. Recent studies suggest a role for aberrant TLR8 and NLRP3 inflammasome activation during both COVID-19 and HIV-1 infection. Here, we show that pacritinib inhibits the TLR8-dependent pro-inflammatory cytokine response elicited by GU-rich single-stranded RNA derived from SARS-CoV-2 and HIV-1. Using genetic and pharmacologic inhibition, we demonstrate that pacritinib inhibits IRAK1 phosphorylation and ubiquitination which then inhibits the recruitment of the TAK1 complex to IRAK1, thus inhibiting the activation of downstream signalling and the production of pro-inflammatory cytokines.

Dual-target Janus kinase (JAK) inhibitors: Comprehensive review on the JAK-based strategies for treating solid or hematological malignancies and immune-related diseases

Janus kinases (JAKs) are the non-receptor tyrosine kinases covering JAK1, JAK2, JAK3, and TYK2 which regulate signal transductions of hematopoietic cytokines and growth factors to play essential roles in cell growth, survival, and development. Dysregulated JAK activity leading to a constitutively activated signal transducers and activators of transcription (STAT) is strongly associated with immune-related diseases and cancers. Targeting JAK to interfere the signaling of JAK/STAT pathway has achieved quite success in the treatment of these diseases. However, inadequate clinical response and serious adverse events come along by the treatment of monotherapy of JAK inhibitors. With better and deeper understanding of JAK/STAT pathway in the pathogenesis of diseases, researchers start to show huge interest in combining inhibition of JAK and other oncogenic targets to realize a broader regulation on pathological processes to block disease development and progression, which has hastened extensive research of dual JAK inhibitors over the past decades. Until now, studies of dual JAK inhibitors have added BTK, SYK, FLT3, HDAC, Src, and Aurora kinases to the overall inhibitory profile and demonstrated significant advantage and superiority over single-target inhibitors. In this review, we elucidated the possible mechanism of synergic effects caused by dual JAK inhibitors and briefly describe the development of these agents.

A Comprehensive Overview of Globally Approved JAK Inhibitors

Janus kinase (JAK) is a family of cytoplasmic non-receptor tyrosine kinases that includes four members, namely JAK1, JAK2, JAK3, and TYK2. The JAKs transduce cytokine signaling through the JAK-STAT pathway, which regulates the transcription of several genes involved in inflammatory, immune, and cancer conditions. Targeting the JAK family kinases with small-molecule inhibitors has proved to be effective in the treatment of different types of diseases. In the current review, eleven of the JAK inhibitors that received approval for clinical use have been discussed. These drugs are abrocitinib, baricitinib, delgocitinib, fedratinib, filgotinib, oclacitinib, pacritinib, peficitinib, ruxolitinib, tofacitinib, and upadacitinib. The aim of the current review was to provide an integrated overview of the chemical and pharmacological data of the globally approved JAK inhibitors. The synthetic routes of the eleven drugs were described. In addition, their inhibitory activities against different kinases and their pharmacological uses have also been explained. Moreover, their crystal structures with different kinases were summarized, with a primary focus on their binding modes and interactions. The proposed metabolic pathways and metabolites of these drugs were also illustrated. To sum up, the data in the current review could help in the design of new JAK inhibitors with potential therapeutic benefits in inflammatory and autoimmune diseases.

An Insight into the Medicinal Chemistry Perspective of Macrocyclic Derivatives with Antitumor Activity: A Systematic Review

The profound pharmacological properties of macrocyclic compounds have led to their development as drugs. In conformationally pre-organized ring structures, the multiple functions and stereochemical complexity provided by the macrocycle result in high affinity and selectivity of protein targets while maintaining sufficient bioavailability to reach intracellular locations. Therefore, the construction of macrocycles is an ideal choice to solve the problem of “undruggable” targets. Inspection of 68 macrocyclic drugs on the market showed that 10 of them were used to treat cancer, but this structural class still has been poorly explored within drug discovery. This perspective considers the macrocyclic compounds used for anti-tumor with different targets, their advantages and disadvantages, and the various synthetic methods of them.

PDGF-R inhibition induces glioblastoma cell differentiation via DUSP1/p38MAPK signalling

Glioblastoma (GBM) is the most common and fatal primary brain tumour in adults. Considering that resistance to current therapies leads to limited response in patients, new therapeutic options are urgently needed. In recent years, differentiation therapy has been proposed as an alternative for GBM treatment, with the aim of bringing cancer cells into a post-mitotic/differentiated state, ultimately limiting tumour growth. As an integral component of cancer development and regulation of differentiation processes, kinases are potential targets of differentiation therapies. The present study describes how the screening of a panel of kinase inhibitors (KIs) identified PDGF-Rα/β inhibitor CP-673451 as a potential differentiation agent in GBM. We show that targeting PDGF-Rα/β with CP-673451 in vitro triggers outgrowth of neurite-like processes in GBM cell lines and GBM stem cells (GSCs), suggesting differentiation into neural-like cells, while reducing proliferation and invasion in 3D hyaluronic acid hydrogels. In addition, we report that treatment with CP-673451 improves the anti-tumour effects of temozolomide in vivo using a subcutaneous xenograft mouse model. RNA sequencing and follow-up proteomic analysis revealed that upregulation of phosphatase DUSP1 and consecutive downregulation of phosphorylated-p38^MAPK can underlie the pro-differentiation effect of CP-673451 on GBM cells. Overall, the present study identifies a potential novel therapeutic option that could benefit GBM patients in the future, through differentiation of residual GSCs post-surgery, with the aim to limit recurrence and improve quality of life.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

Olefin Metathesis in Continuous Flow Reactor Employing Polar Ruthenium Catalyst and Soluble Metal Scavenger for Instant Purification of Products of Pharmaceutical Interest

In recent years, the development of continuous-flow reactors has attracted growing attention from the synthetic community. Moreover, findings in the precise control of the reaction parameters and improved mass/heat transfer have made the flow setup an attractive alternative to batch reactors, both in academia and industry, enabling safe and easy scaling-up of synthetic processes. Even though a majority of the pharmaceutical industry currently rely on batch reactors or semibatch reactors, many are integrating flow technology because of easier maintenance and lower risks. Herein, we demonstrate an operationally simple flow setup for homogeneous ring-closing metathesis, which is applicable to the synthesis of active pharmaceutical ingredients precursors or analogues with high efficiency, low residence time, and in a green solvent. Furthermore, through the addition of a soluble metal scavenger in the subsequent step within the flow system, the level of ruthenium contamination in the final product can be greatly reduced (to less than 5 ppm). To ensure that this method is applicable for industrial usage, an upscale process including a 24 h continuous-flow reaction for more than 60 g of a Sildenafil analogue was achieved in a continuous-flow fashion by adjusting the tubing size and flow rate accordingly.

Second-Generation Jak2 Inhibitors for Advanced Prostate Cancer: Are We Ready for Clinical Development?

Simple Summary

Prostate Cancer (PC) is currently estimated to affect 1 in 9 men and is the second leading cause of cancer in men in the US. While androgen deprivation therapy, which targets the androgen receptor, is one of the front-line therapies for advanced PC and for recurrence of organ-confined PC treated with surgery, lethal castrate-resistant PC develops consistently in patients. PC is a multi-focal cancer with different grade carcinoma areas presenting simultaneously. Jak2-Stat5 signaling pathway has emerged as a potentially highly effective molecular target in PCs with positive areas for activated Stat5 protein. Activated Jak2-Stat5 signaling can be readily targeted by the second-generation Jak2-inhibitors that have been developed for myeloproliferative and autoimmune disorders and hematological malignancies. In this review, we analyze and summarize the Jak2 inhibitors that are currently in preclinical and clinical development.

Abstract

Androgen deprivation therapy (ADT) for metastatic and high-risk prostate cancer (PC) inhibits growth pathways driven by the androgen receptor (AR). Over time, ADT leads to the emergence of lethal castrate-resistant PC (CRPC), which is consistently caused by an acquired ability of tumors to re-activate AR. This has led to the development of second-generation anti-androgens that more effectively antagonize AR, such as enzalutamide (ENZ). However, the resistance of CRPC to ENZ develops rapidly. Studies utilizing preclinical models of PC have established that inhibition of the Jak2-Stat5 signaling leads to extensive PC cell apoptosis and decreased tumor growth. In large clinical cohorts, Jak2-Stat5 activity predicts PC progression and recurrence. Recently, Jak2-Stat5 signaling was demonstrated to induce ENZ-resistant PC growth in preclinical PC models, further emphasizing the importance of Jak2-Stat5 for therapeutic targeting for advanced PC. The discovery of the Jak2V617F somatic mutation in myeloproliferative disorders triggered the rapid development of Jak1/2-specific inhibitors for a variety of myeloproliferative and auto-immune disorders as well as hematological malignancies. Here, we review Jak2 inhibitors targeting the mutated Jak2V617F vs. wild type (WT)-Jak2 that are currently in the development pipeline. Among these 35 compounds with documented Jak2 inhibitory activity, those with potency against WT-Jak2 hold strong potential for advanced PC therapy.

Janus Kinase Signaling: Oncogenic Criminal of Lymphoid Cancers

Simple Summary

Janus kinases (JAKs) are transmembrane receptors that pass signals from extracellular ligands to downstream. Increasing evidence has suggested that JAK family aberrations promote lymphoid cancer pathogenesis and progression through mediating gene expression via the JAK/STAT pathway or noncanonical JAK signaling. We are here to review how canonical JAK/STAT and noncanonical JAK signalings are represented and deregulated in lymphoid malignancies and how to target JAK for therapeutic purposes.

Abstract

The Janus kinase (JAK) family are known to respond to extracellular cytokine stimuli and to phosphorylate and activate signal transducers and activators of transcription (STAT), thereby modulating gene expression profiles. Recent studies have highlighted JAK abnormality in inducing over-activation of the JAK/STAT pathway, and that the cytoplasmic JAK tyrosine kinases may also have a nuclear role. A couple of anti-JAK therapeutics have been developed, which effectively harness lymphoid cancer cells. Here we discuss mutations and fusions leading to JAK deregulations, how upstream nodes drive JAK expression, how classical JAK/STAT pathways are represented in lymphoid malignancies and the noncanonical and nuclear role of JAKs. We also summarize JAK inhibition therapeutics applied alone or synergized with other drugs in treating lymphoid malignancies.

Rational Multitargeted Drug Design Strategy from the Perspective of a Medicinal Chemist

The development of multitarget-directed ligands (MTDLs) has become a widely focused research topic, but rational design remains as an enormous challenge. This paper reviews and discusses the design strategy of incorporating the second activity into an existing single-active ligand. If the binding sites of both targets share similar endogenous substrates, MTDLs can be designed by merging two lead compounds with similar functional groups. If the binding sites are large or adjacent to the solution, two key pharmacophores can be fused directly. If the binding regions are small and deep inside the proteins, the linked-pharmacophore strategy might be the only way. The added pharmacophores of second targets should not affect the binding mode of the original ones. Moreover, the inhibitory activities of the two targets need to be adjusted to achieve an optimal ratio.

Differential Inhibition of Equilibrative Nucleoside Transporter 1 (ENT1) Activity by Tyrosine Kinase Inhibitors

Background and Objectives

Equilibrative nucleoside transporter (ENT) 1 is a widely-expressed drug transporter, handling nucleoside analogues as well as endogenous nucleosides. ENT1 has been postulated to be inhibited by some marketed tyrosine kinase inhibitors (TKIs). To obtain insights into this point, the interactions of 24 TKIs with ENT1 activity have been analyzed.

Methods

Inhibition of ENT1 activity was investigated in vitro through quantifying the decrease of [³H]-uridine uptake caused by TKIs in HAP1 ENT2-knockout cells, exhibiting selective ENT1 expression. TKI effects towards ENT1-mediated transport were additionally characterized in terms of their in vivo relevance and of their relationship to TKI molecular descriptors. Putative transport of the TKI lorlatinib by ENT1/ENT2 was analyzed by LC-MS/MS.

Results

Of 24 TKIs, 12 of them, each used at 10 µM, were found to behave as moderate or strong inhibitors of ENT1, i.e., they decreased ENT1 activity by at least 35%. This inhibition was concentration-dependent for at least the strongest ones (IC₅₀ less than 10 µM) and was correlated with some molecular descriptors, especially with atom-type E-state indices. Lorlatinib was notably a potent in vitro inhibitor of ENT1/ENT2 (IC₅₀ values around 1.0–2.5 µM) and was predicted to inhibit these nucleoside transporters at relevant clinical concentrations, without, however, being a substrate for them.

Conclusion

Our data unambiguously add ENT1 to the list of drug transporters inhibited by TKIs, especially by lorlatinib. This point likely merits attention in terms of possible drug–drug interactions, notably for nucleoside analogues, whose ENT1-mediated uptake into their target cells may be hampered by co-administrated TKIs such as lorlatinib.

Synthetic Opportunities and Challenges for Macrocyclic Kinase Inhibitors

Macrocycles are typically cyclic variants of inhibitors derived from uncyclized canonical molecules or from natural products. For medicinal chemistry, drug-like macrocycles have received increasing interest over the past few years, since it has been demonstrated that macrocyclization can favorably alter the biological and physiochemical properties as well as selectivity in comparison to the acyclic analogue. Recent drug approvals such as Lorlatinib, glecaprevir, or voxilaprevir underline the clinical relevance of drug-like macrocycles. However, the synthesis of drug-like macrocycles can be challenging, since the ring-closing reaction is generally challenging with yields depending on the size and geometry of the bridging linker. Nevertheless, macrocycles are one opportunity to expand the synthetic toolbox for medicinal chemistry to provide bioactive molecules. Therefore, we reviewed the past literature of drug-like macrocycles highlighting reactions that have been successfully used for the macrocyclization. We classified the cyclization reactions by their type, ring-size, yield, and macrocyclization efficiency index.

Studies on the anti-psoriasis effects and its mechanism of a dual JAK2/FLT3 inhibitor flonoltinib maleate

Psoriasis is a chronic, inflammatory autoimmune disease mediated by T cells, and characterized with abnormal proliferation and differentiation of keratinocytes, and inflammatory infiltration. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway has been identified to play essential roles in mediating various of biological processes, and is closely related to autoimmune diseases. Dendritic cells (DCs) are important antigen presenting cells and play an important regulatory role in T cells. The proliferation, differentiation and function of DCs are regulated by JAK and FMS-like tyrosine kinase 3 (FLT3) signal pathways. Flonoltinib maleate (FM), a high selectivity dual JAK2/FLT3 inhibitor with IC50 values of 0.8 nM and 15 nM for JAK2 and FLT3, respectively, was developed by our laboratory. Moreover, FM was a potent JAK2 inhibitor with 863-fold and 696-fold selectivity over JAK1 and JAK3, respectively. In this study, the anti-psoriasis activity of FM was evaluated both in vitro and in vivo. FM effectively inhibited the proliferation of HaCaT, the inflammatory keratinocyte induced by M5 and markedly suppressed the generation and differentiation of DCs from bone marrow (BM), and inhibited the expression of FLT3 in DCs in vitro. FM effectively inhibited the ear thickening and improved the pathological changes of the ear in interleukin (IL)-23-induced psoriasis-like acanthosis mouse model. Further in keratin 14-vascular endothelial growth factor (K14-VEGF) transgenic homozygous mice model, FM could obviously improve the psoriatic symptom and pathological changes, significantly inhibit the generations of Th1 and Th17 cells in the spleen, and the accumulations of DCs in the ears. FM could also significantly reduce the expression of various inflammatory factors both in C57BL/6 and K14-VEGF mice ears, and the serum of K14-VEGF mice. Mechanism revealed that FM effectively suppressed the phosphorylation of JAK2, STAT3 and STAT5 in inflammatory keratinocytes and the mice ears of C57BL/6 and K14-VEGF, as well as the phosphorylation of FLT3 in K14-VEGF mice ears. In conclusion, FM plays an excellent anti-psoriasis activity, including inhibiting keratinocyte proliferation and regulating inflammatory response through inhibiting JAK2 and FLT3 signaling pathway.

Microwave-Assisted Regioselective Suzuki Coupling of 2,4-Dichloropyrimidines with Aryl and Heteroaryl Boronic Acids

Suzuki coupling reaction has been often used for the preparation of a diverse set of substituted pyrimidines. In this study, the Suzuki coupling of 2,4-dichloropyrimidines with aryl and heteroaryl boronic acids was investigated. A thorough screening of reaction conditions and the use of microwave irradiation led to a very efficient and straightforward synthetic procedure providing C4-substituted pyrimidines in good to excellent yields. Short reaction time (15 min) and extremely low catalyst loading (0.5 mol%) are the main advantages of our tetrakis(triphenylphosphine)palladium(0) catalyzed microwave-assisted procedure, which could be used for quick and low-cost regioselective preparation of substituted pyrimidine rings.

Discovery of imidazopyrrolopyridines derivatives as novel and selective inhibitors of JAK2

Herein, we describe the design, synthesis, and structure-activity relationships of a series of imidazopyrrolopyridines derivatives that selectively inhibit Janus kinase 2 (JAK2). These screening cascades revealed that 6k was a preferred compound, with IC₅₀ values of 10 nM for JAK2. Moreover, 6k was a selective JAK2 inhibitor with 19-fold, >30-fold and >30-fold selectivity over JAK1, JAK3 and TYK2 respectively. In cytokine-stimulated cell-based assays, 6k exhibited a higher JAK2 selectivity over JAK1 isoforms. Indeed, at a dose of 20 mg/kg compound 6k, pSTAT3 and pSTAT5 expression was reduced to levels comparable to those of control animals untreated with GM-CSF. Additionally, 6k showed a relatively good bioavailability (F = 38%), a suitable half-life time (T_1/2 = 1.9 h), a satisfactory metabolic stability, suggesting that 6k might be a promising inhibitor of JAK2 for further development research for the treatment of MPNs.

A Review of Progress in Histone Deacetylase 6 Inhibitors Research: Structural Specificity and Functional Diversity

Histone deacetylases (HDACs) are essential for maintaining homeostasis by catalyzing histone deacetylation. Aberrant expression of HDACs is associated with various human diseases. Although HDAC inhibitors are used as effective chemotherapeutic agents in clinical practice, their applications remain limited due to associated side effects induced by weak isoform selectivity. HDAC6 displays unique structure and cellular localization as well as diverse substrates and exhibits a wider range of biological functions than other isoforms. HDAC6 inhibitors have been effectively used to treat cancers, neurodegenerative diseases, and autoimmune disorders without exerting significant toxic effects. Progress has been made in defining the crystal structures of HDAC6 catalytic domains which has influenced the structure-based drug design of HDAC6 inhibitors. This review summarizes recent literature on HDAC6 inhibitors with particular reference to structural specificity and functional diversity. It may provide up-to-date guidance for the development of HDAC6 inhibitors and perspectives for optimization of therapeutic applications.