JAK selectivity: more precision less troubles

Small molecule drug discovery targeting the JAK-STAT pathway

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway functions as a central hub for transmitting signals from more than 50 cytokines, playing a pivotal role in maintaining hematopoiesis, immune balance, and tissue homeostasis. Dysregulation of this pathway has been implicated in various diseases, including immunodeficiency, autoimmune conditions, hematological disorders, and certain cancers. Proteins within this pathway have emerged as effective therapeutic targets for managing these conditions, with various approaches developed to modulate key nodes in the signaling process, spanning from receptor engagement to transcription factor activation. Following the success of JAK inhibitors such as tofacitinib for RA treatment and ruxolitinib for managing primary myelofibrosis, the pharmaceutical industry has obtained approvals for over 10 small molecule drugs targeting the JAK-STAT pathway and many more are at various stages of clinical trials. In this review, we consolidate key strategies employed in drug discovery efforts targeting this pathway, with the aim of contributing to the collective understanding of small molecule interventions in the context of JAK-STAT signaling. We aspire that our endeavors will contribute to advancing the development of innovative and efficacious treatments for a range of diseases linked to this pathway dysregulation.

Insights into the effects of chronic combined chromium-nickel exposure on colon damage in mice through transcriptomic analysis and in vitro gastrointestinal digestion assay

Heavy metals interact with each other in a coexisting manner to produce complex combined toxicity to organisms. At present, the toxic effects of chronic co-exposure to heavy metals hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] on organisms are seldom studied and the related mechanisms are poorly understood. In this study, we explored the mechanism of the colon injury in mice caused by chronic exposure to Cr or/and Ni. The results showed that, compared with the control group, Cr or/and Ni chronic exposure affected the body weight of mice, and led to infiltration of inflammatory cells in the colon, decreased the number of goblet cells, fusion of intracellular mucus particles and damaged cell structure of intestinal epithelial. In the Cr or/and Ni exposure group, the activity of nitric oxide synthase (iNOS) increased, the expression levels of MUC2 were significantly down-regulated, and those of ZO-1 and Occludin were significantly up-regulated. Interestingly, factorial analysis revealed an interaction between Cr and Ni, which was manifested as antagonistic effects on iNOS activity, ZO-1 and MUC2 mRNA expression levels. Transcriptome sequencing further revealed that the expression of genes-related to inflammation, intestinal mucus and tight junctions changed obviously. Moreover, the relative contents of Cr(VI) and Ni(II) in the Cr, Ni and Cr+Ni groups all changed with in-vitro gastrointestinal （IVG）digestion, especially in the Cr+Ni group. Our results indicated that the chronic exposure to Cr or/and Ni can lead to damage to the mice colon, and the relative content changes of Cr(VI) and Ni(II) might be the main reason for the antagonistic effect of Cr+Ni exposure on the colon damage.

Design, synthesis and evaluation of C-5 substituted pyrrolopyridine derivatives as potent Janus Kinase 1 inhibitors with excellent selectivity

The development of highly selective Janus Kinase 1 (JAK1) inhibitors is crucial for improving efficacy and minimizing adverse effects in the clinical treatment of autoimmune diseases. In a prior study, we designed a series of C-5 4-pyrazol substituted pyrrolopyridine derivatives that demonstrated significant potency against JAK1, with a 10 ∼ 20-fold selectivity over Janus Kinase 2 (JAK2). Building on this foundation, we adopted orthogonal strategy by modifying the C-5 position with 3-pyrazol/4-pyrazol/3-pyrrol groups and tail with substituted benzyl groups on the pyrrolopyridine head to enhance both potency and selectivity. In this endeavor, we have identified several compounds that exhibit excellent potency and selectivity for JAK1. Notably, compounds 12b and 12e, which combined 4-pyrazol group at C-5 site and meta-substituted benzyl tails, displayed IC50 value with 2.4/2.2 nM and high 352-/253-fold selectivity for JAK1 over JAK2 in enzyme assays. Additionally, both compounds showed good JAK1-selective in Ba/F3-TEL-JAK1/2 cell-based assays. These findings mark a substantial improvement, as these compounds are 10-fold more potent and over 10-fold more selective than the best compound identified in our previous study. The noteworthy potency and selectivity properties of compounds 12b and 12e suggest their potential utility in furthering the development of drugs for autoimmune diseases.

Letter: Elderly onset inflammatory bowel disease-Treat to target approach is still warranted

This article is linked to Nørgård et al paper. To view this article, visit https://doi.org/10.1111/apt.17520

Discovery of a Potent and Selective Tyrosine Kinase 2 Inhibitor: TAK-279

TYK2 is a key mediator of IL12, IL23, and type I interferon signaling, and these cytokines have been implicated in the pathogenesis of multiple inflammatory and autoimmune diseases such as psoriasis, rheumatoid arthritis, lupus, and inflammatory bowel diseases. Supported by compelling data from human genome-wide association studies and clinical results, TYK2 inhibition through small molecules is an attractive therapeutic strategy to treat these diseases. Herein, we report the discovery of a series of highly selective pseudokinase (Janus homology 2, JH2) domain inhibitors of TYK2 enzymatic activity. A computationally enabled design strategy, including the use of FEP+, was instrumental in identifying a pyrazolo-pyrimidine core. We highlight the utility of computational physics-based predictions used to optimize this series of molecules to identify the development candidate 30, a potent, exquisitely selective cellular TYK2 inhibitor that is currently in Phase 2 clinical trials for the treatment of psoriasis and psoriatic arthritis.

Discovery of C-5 Pyrazole-Substituted Pyrrolopyridine Derivatives as Potent and Selective Inhibitors for Janus Kinase 1

Developing selective inhibitors for Janus kinase 1 (JAK1) is a significant focus for improving the efficacy and alleviating the adverse effects in treating immune-inflammatory diseases. Herein, we report the discovery of a series of C-5 pyrazole-modified pyrrolopyrimidine derivatives as JAK1-selective inhibitors. The potential hydrogen bond between the pyrazole group and E966 in JAK1 is the key point that enhances JAK1 selectivity. These compounds exhibit 10- to 20-fold JAK1 selectivity over JAK2 in enzyme assays. Compound 12b also exhibits excellent JAK1 selectivity in Ba/F3-TEL-JAK cellular assays. Metabolism studies and the results of the hair growth model in mice indicate that compound 12b may be a viable lead compound for the development of highly JAK1-selective inhibitors for immune and inflammatory diseases.

Review article: Risk of cardiovascular events in patients with inflammatory bowel disease receiving small molecule drugs

BACKGROUND

In the context of an ageing inflammatory bowel disease (IBD) population, cardiovascular comorbidities become particularly relevant. Novel small molecule drugs (SMDs) for the treatment of moderate-to-severe IBD have been recently approved, including Janus kinase (JAK) inhibitors and sphingosine-1-phosphate receptor (S1P) modulators. Data from rheumatoid arthritis population have raised concerns about the risk of cardiovascular events with the use of tofacitinib, which was extrapolated to other immune-mediated diseases and other JAK inhibitors. S1P receptor modulation has been associated with potential cardiovascular events, especially bradycardia and cardiac conduction abnormalities.

AIM

To review the incidence of cardiovascular events with the use of SMDs in patients with IBD and to provide practical recommendations on mitigation strategies.

METHODS

Published literature was reviewed; recommendations were synthesised by experts in both cardiovascular diseases and IBD.

RESULTS

Evidence from the IBD population does not indicate a higher risk of cardiovascular events with tofacitinib and other JAK inhibitors. The risk is higher in patients with intermediate to high cardiovascular risk. S1P modulators may be associated with a dose-dependent, first-dose effect, transient risk of conduction abnormalities (bradycardia and AV block). Screening and monitoring of cardiovascular risk factors should be done in all patients with IBD. Risk stratification for cardiovascular disease should be performed before starting treatment with SMDs.

CONCLUSIONS

Available evidence of both JAK inhibitors and S1P modulators indicates a reassuring safety profile of SMDs from the cardiovascular perspective in the overall IBD population. Efforts should be made to identify patients with IBD at a higher risk of cardiovascular events.

Filgotinib for moderately to severely active ulcerative colitis

INTRODUCTION

Filgotinib is an oral Janus kinase type 1 (JAK1) selective inhibitor with demonstrated efficacy and safety in ulcerative colitis (UC). The aim of this review is to summarize the available evidence on pharmacological characteristics, efficacy, and safety of filgotinib in UC.

AREAS COVERED

Pubmed, Scopus, and Embase databases were searched for all relevant studies reporting the efficacy and safety of filgotinib in patients with moderate to severe UC. We particularly focused on the risk of zoster infection and venous thromboembolism compared to other JAK inhibitors.

EXPERT OPINION

Filgotinib has remarkable efficacy, safety, and tolerability profiles in the treatment of moderate-to-severe active UC. It can be used in both biologic-naïve and biologic-experienced patients. The rapid mechanism of action and its oral administration route make it a reliable therapeutic option.

Potent and selective TYK2-JH1 inhibitors highly efficacious in rodent model of psoriasis

TYK2 is a member of the JAK family of kinases and a key mediator of IL-12, IL-23, and type I interferon signaling. These cytokines have been implicated in the pathogenesis of multiple inflammatory and autoimmune diseases such as psoriasis, rheumatoid arthritis, lupus, and inflammatory bowel diseases. Supported by compelling data from human genetic association studies, TYK2 inhibition is an attractive therapeutic strategy for these diseases. Herein, we report the discovery of a series of highly selective catalytic site TYK2 inhibitors designed using FEP+ and structurally enabled design starting from a virtual screen hit. We highlight the structure-based optimization to identify a lead candidate 30, a potent cellular TYK2 inhibitor with excellent selectivity, pharmacokinetic properties, and in vivo efficacy in a mouse psoriasis model.

JAK Inhibition as a New Treatment Strategy for Patients with COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic continues to spread globally. The rapid dispersion of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 drives an urgent need for effective treatments, especially for patients who develop severe pneumonia. The excessive and uncontrolled release of pro-inflammatory cytokines has proved to be an essential factor in the rapidity of disease progression, and some cytokines are significantly associated with adverse outcomes. Most of the upregulated cytokines signal through the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway. Therefore, blocking the exaggerated release of cytokines, including IL-2, IL-6, TNF-α, and IFNα/β/γ, by inhibiting JAK/STAT signaling will, presumably, offer favorable pharmacodynamics and present an attractive prospect. JAK inhibitors (JAKi) can also inhibit members of the numb-associated kinase (NAK) family, including AP2-associated kinase 1 (AAK1) and cyclin G-associated kinase (GAK), which regulate the angiotensin-converting enzyme 2 (ACE-2) transmembrane protein and are involved in host viral endocytosis. According to the data released from current clinical trials, JAKi treatment can effectively control the dysregulated cytokine storm and improve clinical outcomes regarding mortality, ICU admission, and discharge. There are still some concerns surrounding thromboembolic events, opportunistic infection such as herpes zoster virus reactivation, and repression of the host's type-I IFN-dependent immune repair for both viral and bacterial infection. However, the current JAKi clinical trials of COVID-19 raised no new safety concerns except a slightly increased risk of herpes virus infection. In the updated WHO guideline, Baricitinb is strongly recommended as an alternative to IL-6 receptor blockers, particularly in combination with corticosteroids, in patients with severe or critical COVID-19. Future studies will explore the application of JAKi to COVID-19 treatment in greater detail, such as the optimal timing and course of JAKi treatment, individualized medication strategies based on pharmacogenomics, and the effect of combined medications.

Design of Rational JAK3 Inhibitors Based on the Parent Core Structure of 1,7-Dihydro-Dipyrrolo [2,3-b:3',2'-e] Pyridine

JAK3 differs from other JAK family members in terms of tissue distribution and functional properties, making it a promising target for autoimmune disease treatment. However, due to the high homology of these family members, targeting JAK3 selectively is difficult. As a result, exploiting small changes or selectively boosting affinity within the ATP binding region to produce new tailored inhibitors of JAK3 is extremely beneficial. PubChem CID 137321159 was used as the lead inhibitor in this study to preserve the characteristic structure and to collocate it with the redesigned new parent core structure, from which a series of 1,7-dihydro-dipyrrolo [2,3-b:3′,2′-e] pyridine derivatives were obtained using the backbone growth method. From the proposed compounds, 14 inhibitors of JAK3 were found based on the docking scoring evaluation. The RMSD and MM/PBSA methods of molecular dynamics simulations were also used to confirm the stable nature of this series of complex systems, and the weak protein−ligand interactions during the dynamics were graphically evaluated and further investigated. The results demonstrated that the new parent core structure fully occupied the hydrophobic cavity, enhanced the interactions of residues LEU828, VAL836, LYS855, GLU903, LEU905 and LEU956, and maintained the structural stability. Apart from this, the results of the analysis show that the binding efficiency of the designed inhibitors of JAK3 is mainly achieved by electrostatic and VDW interactions and the order of the binding free energy with JAK3 is: 8 (−70.286 kJ/mol) > 11 (−64.523 kJ/mol) > 6 (−51.225 kJ/mol) > 17 (−42.822 kJ/mol) > 10 (−40.975 kJ/mol) > 19 (−39.754 kJ/mol). This study may provide a valuable reference for the discovery of novel JAK3 inhibitors for those patients with immune diseases.

Efficacy, Safety and Future Perspectives of JAK Inhibitors in the IBD Treatment

Although development of biologics has importantly improved the effectiveness in inducing and maintaining remission in inflammatory bowel disease (IBD), biologic therapies still have several limitations. Effective, low-cost drug therapy with good safety profile and compliance is therefore a substantial unmet medical need. A promising target for IBD treatment strategies are Janus kinase (JAK) inhibitors, which are small molecules that interact with cytokines implicated in pathogenesis of IBD. In contrast to monoclonal antibodies, which are able to block a single cytokine, JAK inhibitors have the potential to affect multiple cytokine-dependent immune pathways, which may improve the therapeutic response in some IBD patients. Tofacitinib, inhibiting signaling via different types of JAKs, has been already approved for ulcerative colitis, and several other small-molecule are still under investigation. However, one of the main concerns about using JAK inhibitors is the risk of thromboembolic events. Moreover, patients with COVID-19 appear to have an increased susceptibility for immunothrombosis. Therefore, thrombotic complications may become a serious limitation in the use of JAK inhibitors in the SARS-CoV-2 pandemic. As many questions about safety and efficacy of small molecules still remain unclear, in our review we present the current data regarding approved JAK inhibitors, as well as those in clinical development for the treatment of IBD.