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Introduction: Alopecia Areata (AA), characterized by non-scarring hair loss due to the dysregulation of the JAK/STAT pathway, has long lacked effective treatment. In 2023, Ritlecitinib, a novel Janus kinase (JAK) 3 and tyrosine kinase family inhibitor, received its first approval from the US FDA to treat AA, followed by approvals in Japan, Europe, China, and the UK. This development aims to address the challenges faced by millions of individuals affected by this condition globally., Areas Covered: This review offers an overview of Ritlecitinib's pharmacological properties, biological targets, and development strategies. It examines its mechanism of action, pharmacokinetics, pharmacodynamics, and clinical trial insights. Additionally, it covers the drug's chemical synthesis, contraindications, drug interactions, and potential adverse effects, with special attention to its use in adolescents, pregnant women, and the elderly., Expert Opinion: Ritlecitinib represents a significant advancement in treating AA, offering a targeted approach with promising efficacy and a favorable safety profile. While long-term safety data and real-world effectiveness studies are needed, its oral administration and efficacy in both adults and adolescents position it as a potentially transformative therapy. Ongoing research should focus on optimizing treatment strategies, identifying predictive biomarkers, and assessing cost-effectiveness to fully realize Ritlecitinib's potential in improving outcomes.

The JAK-STAT signalling pathway is considered to be a significant role involved in the regulation of inflammatory diseases and immune responses, which indicate that specific inhibition of JAK-STAT pathway would be a potential key strategy for RA (Rheumatoid arthritis) treatment. Cedrol (CE), found from ginger by our group earlier, has been proven to play an excellent role in ameliorating RA via acting on JAK3. In this study, 27 new (1, 3-28), along with one known (2) derivatives of CE were synthesized by using chloroacetic acid and acryloyl chloride as intermediate ligands. In vitro, the inhibition effect on JAK kinases were performed using HTRF (Homogenous Time-Resolved Fluorescence) detection technology, which is more convenient and stable than traditional methods. The results compared with the secretion of LPS-induced p-JAK3 can better reflect the true kinase-selective effect of the compounds. Compound 22 was identified as a potent inhibitor to reduce the secretion of LPS-induced p-JAK3 with a dose-dependent manner. Given these results, compound 22 could serve as a favourable inhibitor of JAK3 for further research., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Wei Li reports financial support was provided by Natural Science Foundation of Liaoning. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

To investigate the protective role of immune response gene 1 (IRG1) and exogenous itaconate in autoimmune hepatitis (AIH) and elucidate the underlying mechanisms. Wild-type and IRG1 -/- AIH mouse models were established, and samples of liver tissue and ocular blood were collected from each group of mice to assess the effects of IRG1/itaconate on the expression of pro- and anti-inflammatory cytokines. The levels of liver enzymes and related inflammatory factors were determined using enzyme-linked immunosorbent assay and real-time quantitative polymerase chain reaction (PCR). Liver histomorphology was detected through hematoxylin and eosin staining and then scored for liver injury, and the infiltration levels of tissue-resident memory T (TRM) cells and related molecules in the liver tissue were detected through immunofluorescence staining in vitro. RNA sequencing and gene enrichment analysis were conducted to identify the corresponding molecules and pathways, and lentiviral transfection was used to generate TRM cell lines with IRG1, Jak3, Stat3, and p53 knockdown. Real-time quantitative PCR and western blot were performed to detect the expression levels of relevant mRNAs and proteins in the liver tissue and cells. The percentage of apoptotic cells was determined using flow cytometry. IRG1/itaconate effectively reduced the release of pro-inflammatory cytokines and the pathological damage to liver tissue, thereby maintaining normal liver function. At the same time, IRG1/itaconate inhibited the JAK3/STAT3 signaling pathway, regulated the expression of related downstream proteins, and inhibited the proliferation and promoted the apoptosis of CD69 + CD103 + CD8 + TRM cells. For the first time, P53 was found to act as a downstream molecule of the JAK3/STAT3 pathway and was regulated by IRG1/itaconate to promote the apoptosis of CD8 + TRM cells. IRG1/itaconate can alleviate concanavalin A-induced autoimmune hepatitis in mice by inhibiting the proliferation and promoting the apoptosis of CD69 + CD103 + CD8 + TRM cells via the JAK3/STAT3/P53 pathway., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Glioblastoma (GBM) is a brain tumor characterized by its aggressive and invasive properties. It is found that STAT3 is abnormally activated in GBM, and inhibiting STAT3 signaling can effectively suppress tumor progression. In this study, novel pyrimidine compounds, BY4003 and BY4008, were synthesized to target the JAK3/STAT3 signaling pathway, and their therapeutic efficacy and mechanisms of action were evaluated and compared with Tofacitinib in U251, A172, LN428 and patient-derived glioblastoma cells. The ADP-Glo™ kinase assay was utilized to assessed the inhibitory effects of BY4003 and BY4008 on JAK3, a crucial member of the JAK family. The results showed that both compounds significantly inhibited JAK3 enzyme activity, with IC 50 values in the nanomolar range. The antiproliferative effects of BY4003, BY4008, and Tofacitinib on GBM and patient-derived glioblastoma cells were evaluated by MTT and H&E assays. The impact of BY4003 and BY4008 on GBM cell migration and apoptosis induction was assessed through wound healing, transwell, and TUNEL assays. STAT3-regulated protein expression and relative mRNA levels were analyzed by western blotting, immunocytochemistry, immunofluorescence, and qRT-PCR. It was found that BY4003, BY4008 and Tofacitinib could inhibit U251, A172, LN428 and patient-derived glioblastoma cells growth and proliferation. Results showed decreased expression of STAT3-associated proteins, including p-STAT3, CyclinD1, and Bcl-2, and increased expression of Bax, a pro-apoptotic protein, as well as significant down-regulation of STAT3 and STAT3-related genes. These findings suggested that BY4003 and BY4008 could inhibit GBM growth by suppressing the JAK3/STAT3 signaling pathway, providing valuable insights into the therapeutic development of GBM., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

In this study, we used phenylpyrimidine derivatives with known biological activity against JAK3, a critical tyrosine kinase enzyme involved in signaling pathways, to find similar compounds as potential treatments for rheumatoid arthritis. These inhibitors inhibited JAK3 activity by forming a covalent bond with the Cys909 residue, which resulted in a strong inhibitory effect. Phenylpyrimidine is considered a promising therapeutic target. For pharmacophore modeling, 39 phenylpyrimidine derivatives with high pIC50 (Exp) values were chosen. The best pharmacophore model produced 28 molecules, and the five-point common pharmacophore hypothesis from P HASE (DHRRR_1) revealed the requirement for a hydrogen bond donor feature, a hydrophobic group feature, and three aromatic ring features for further design. The validation of the pharmacophore model phase was performed through 3D-QSAR using partial least squares (P LS). The 3D-QSAR study produced two successful models, an atom-based model (R2 = 0.95; Q2 = 0.67) and a field-based model (R2 = 0.93; Q2 = 0.76), which were used to predict the biological activity of new compounds. The pharmacophore model successfully distinguished between active and inactive medications, discovered potential JAK3 inhibitors, and demonstrated validity with a ROC of 0. 77. ADME-Tox was used to eliminate compounds that might have adverse effects. The best pharmacokinetics and affinity derivatives were selected for covalent docking. A molecular dynamics simulation of the selected molecules and the protein complex was performed to confirm the stability of the interaction with JAK3, whereas MM/GBSA simulations further confirmed their binding affinity. By using the principle of retrosynthesis, we were able to map out a pathway for synthesizing these potential drug candidates. This study has the potential to offer valuable and practical insights for optimizing novel derivatives of phenylpyrimidine.Communicated by Ramaswamy H. Sarma.

Janus Kinase 3 (JAK3) is important for the signaling transduction of cytokines in immune cells and is identified as potential target for treatment of rheumatoid arthritis (RA). Recently, we designed and synthesized two JAK3 inhibitors J1b and J1f, which featured with high selectivity but mild bioactivity. Therefore, in present study the structure was optimized to increase the potency. As shown in the results, most of the compounds synthesized showed stronger inhibitory activities against JAK3 in contrast to the lead compounds, among which 9a was the most promising candidate because it had the most potent effect in ameliorating carrageenan-induced inflammation of mice and exhibited low acute in vivo toxicity (MTD > 2 g/kg). Further analysis revealed that 9a was highly selective to JAK3 (IC 50  = 0.29 nM) with only minimal effect on other JAK members (>3300-fold) and those kinases bearing a thiol in a position analogous to that of Cys909 in JAK3 (>150-fold). Meanwhile, the selectivity of JAK3 was also confirmed by PBMC stimulation assay, in which 9a irreversibly bound to JAK3 and robustly inhibited the signaling transduction with mild suppression on other JAKs. Moreover, it was showed that 9a could remarkably inhibited the proliferation of lymphocytes in response to concanavalin A and significantly mitigate disease severity in collagen induced arthritis. Therefore, present data indicate that compound 9a is a selective JAK3 inhibitor and could be a promising candidate for clinical treatment of RA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Autoimmune dermatosis (AID) occurs when the body's immune system attacks skin or tissue, leading to various types of skin disorders or injuries. Recent studies show that Janus kinases (JAKs) play critical roles in autoimmune diseases including AID by regulating multiple cytokine signaling pathways. CS12192, a novel JAK3/JAK1/TBK1 inhibitor, has been reported to exert ameliorative effects in rheumatoid arthritis. However, the efficacy of CS12192 on AID is undetermined. This study aims to investigate the therapeutic efficacy of CS12192 on psoriasis (PSO), systemic lupus erythematosus (SLE) and atopic dermatitis (AD) in mouse models., Methods: Interleukin-23 (IL-23)-induced PSO model, spontaneous SLE model of MRL/MpJ-Faslpr/J (MRL/lpr) mice, and oxazolone (OXA) and dinitrochlorobenzene (DNCB)-induced murine AD models were used for the evaluation of curative effects of CS12192, respectively. The skin lesion, biochemical parameters, ear thickness, ear weight and histopathology were assessed accordingly., Results: In PSO model, mice treated with CS12192 show reduced ear thickness and ear weight as compared with vehicle. In SLE model, CS12192 ameliorates cutaneous parameters such as lymphadenectasis and skin lesion but not systematic parameters such as proteinuria concentration and score, serum dsDNA and BUN concentration. In AD models, CS12192 dose-dependently improves ear swelling and reduces histological scores, exerting equivalent efficacy with baricitinib, a marketed JAK1/JAK2 inhibitor., Conclusion: Our findings suggest that the novel JAK3/JAK1/TBK1 inhibitor CS12192 is potentially to alleviate autoimmune dermatosis.

Background: Despite the significant role of JAK3 in various autoimmune diseases, including graft-versus-host disease (GVHD), there has been a lack of potent and selective JAK3 inhibitors specifically studied for GVHD. In our preclinical investigations, we evaluated a novel JAK3 inhibitor called CS12192, which is already undergoing clinical investigation in autoimmune diseases., Methods: We evaluated the efficacy of CS12192 in GVHD through mixed lymphocyte reaction (MLR) in both mouse and human cells, as well as allogeneic bone marrow transplantation (BMT) in a murine model., Results: CS12192, starting at a concentration of 0.5 μM, dose-dependently reduced the intracellular positivity for cytokines TNF-α and IFN-γ in CD4+ T cells (p < 0.05 to p < 0.0001) and CD8+ T cells (p < 0.01 to p < 0.0001) during mouse allogeneic MLR assays. This effect was observed for both single and double positivity of the cytokines. Moreover, In MLR assays with three different human donors, CS12192 also demonstrated a dose-dependent reduction in the proportion of IFN-γ positive CD4+ T cells (p < 0.0001) and CD8+ T cells (p < 0.01 to p < 0.0001). Additionally, it suppressed T cell proliferation in the mouse MLR (p < 0.05 to p < 0.0001), but this effect was observed in only one human donor (p < 0.001 to p < 0.0001). Furthermore, the administration of CS12192 at 40 and 80 mg/kg BID significantly improved the survival rate in the BMT model, resulting in cumulative 62-day survival rates of 88.89% (p < 0.01) and 100% (p < 0.001), respectively, compared with prednisolone (p < 0.05)., Conclusions: CS12192 is a novel, potent and selective JAK3 inhibitor demonstrating great potential to mitigate acute GVHD., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The efficacy of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on active and stable lesions was evaluated in patients with active non-segmental vitiligo in a phase 2b trial (NCT03715829). Patients were randomized to placebo or daily ritlecitinib 50 mg (with or without 4-week 100-mg or 200-mg loading dose), 30 mg, or 10 mg for 24 weeks. Active lesions showed greater baseline expression of inflammatory/immune markers IFNG and CCL5, levels of CD103, and T-cell infiltrates than stable lesions. Patients with more active than stable vitiligo lesions showed higher baseline serum levels of CXCL9 and PD-L1, while patients with more stable than active lesions showed higher baseline serum levels of HO-1. At Week 24, ritlecitinib 50 mg significantly stabilized mean percent change from baseline in depigmentation extent in both active lesions and stable lesions vs. placebo-response, with stable lesions showing greater repigmentation. After 24 weeks of treatment, ritlecitinib 50 mg increased expression of melanocyte markers in stable lesions, while Th1/Th2-related and co-stimulatory molecules decreased significantly in both stable and active lesions. Serum from patients with more active than stable lesions showed decreased levels of ICOS and NK cell activation markers. These data, confirmed at transcription/protein levels, indicate that stable lesion repigmentation occurs early with ritlecitinib, while active lesions require stabilization of inflammation first. ClinicalTrials.gov: NCT03715829., (© 2024. The Author(s).)

Selective inhibition of Janus kinase 3 (JAK3) is a promising strategy for the treatment of autoimmune diseases. Based on the discovery of a hydrophobic pocket unutilized between the lead compound RB1 and the JAK3 protein, a series of covalent JAK3 inhibitors were prepared by introducing various aromatic fragments to RB1. Among them, J1b (JAK3 IC 50  = 7.2 nM, other JAKs IC 50  > 1000 nM) stood out because of its low toxicity (MTD > 2 g/kg) and superior anti-inflammatory activity in Institute of Cancer Research mice. Moreover, the acceptable bioavailability (F% = 31.69%) ensured that J1b displayed excellent immune regulation in collagen-induced arthritis mice, whose joints in the high-dose group were almost recovered to a normal state. Given its clear kinase selectivity (Bmx IC 50  = 539.9 nM, other Cys909 kinases IC 50  > 1000 nM), J1b was nominated as a highly selective JAK3 covalent inhibitor, which could be used to safely treat arthritis and other autoimmune diseases., (© 2024 Deutsche Pharmazeutische Gesellschaft.)

Rheumatoid arthritis is a prevalent and debilitating chronic disease worldwide. Targeting Janus kinase 3 (JAK3) has emerged as a crucial molecular strategy to treat this condition. In this study, we employed a comprehensive theoretical approach that included 3D-QSAR, covalent docking, ADMET, and molecular dynamics to propose and optimize new anti-JAK3 compounds. We investigated a series of 28 1H-pyrazolo[3.4-d]pyrimidin-4-amino inhibitors and developed a highly accurate 3D-QSAR model using comparative molecular similarity index analysis (COMSIA). The model predicted with Q 2 = 0.59, R 2 = 0.96, and R 2 (Pred) = 0.89, was validated using Y-randomization and external validation methods. Our covalent docking studies identified T3 and T5 as highly potent inhibitors of JAK3 compared to the reference ligand 17. Additionally, we evaluated the ADMET properties and drug similarity of our newly developed compounds and reference ligand, providing critical insights for further optimization of anti-JAK3 medications. Furthermore, MM-GBSA analysis showed promising results for the designed compounds. Finally, we validated our docking results using molecular dynamics simulations, which confirmed the stability of hydrogen bonding contacts with key residues required to block JAK3 activity. Our findings offer new chemical scaffolds and insights that could lead to the development of novel and effective JAK3 therapeutic targets for treating rheumatoid arthritis.Communicated by Ramaswamy H. Sarma.

Rheumatoid arthritis is a common chronic disabling inflammatory disease that is characterized by inflammation of the synovial membrane and leads to discomfort. In the current study, twenty-seven 1,6-disubstituted 1 H -pyrazolo[3,4- d ]pyrimidines were tested as potential selective inhibitors of the tyrosine-protein kinase JAK3 using a number of molecular modeling methods. The activity of the screened derivatives was statistically quantified using multiple linear regression and artificial neural networks. To assess the quality, robustness, and predictability of the generated models, the leave-one-out cross-validation method was applied with favorable results (Q 2 = 0.75) and Y-randomization. In addition, the evaluation of the predictive ability of the established model was confirmed by means of an external validation using a composite test set and an applicability domain approach. The covalent docking indicated that the tested 1 H -pyrazolo[3,4- d ]pyrimidines containing the acrylic aldehyde moiety had irreversible interaction with the residue Cys909 in the active sites of the tyrosine-protein kinase JAK3 by Michael addition. The molecular dynamics for three selected derivatives (compounds 9 , 12 , and 18 ) were used to verify the covalent docking by determining the stability of hydrogen bonding interactions with active sites, which are needed to stop tyrosine-protein kinase JAK3. The results obtained showed that the tested compounds containing acrylic aldehyde moiety had favorable binding free energies, indicating a strong affinity for the JAK3 enzyme. Overall, this current study suggests that the tested compounds containing the acrylic aldehyde moiety have the potential to act as anti-JAK3 inhibitors. They could be explored further to be used as treatment options for rheumatoid arthritis.Communicated by Ramaswamy H. Sarma.

Peficitinib is a selective Janus kinase (JAK3) inhibitor recently developed and approved for the treatment of rheumatoid arthritis in Japan. Glycolysis in macrophages could induce NOD-like receptor (NLR) family and pyrin domain-containing protein 3 (NLRP3) inflammasome activation, thus resulting in pyroptosis and acute lung injury (ALI). The aim of our study was to investigate whether Peficitinib could alleviate lipopolysaccharide (LPS)-induced ALI by inhibiting NLRP3 inflammasome activation. Wild type C57BL/6J mice were intraperitoneally injected with Peficitinib (5 or 10 mg·kg -1 ·day -1 ) for 7 consecutive days before LPS injection. The results showed that Peficitinib pretreatment significantly relieved LPS-induced pulmonary edema, inflammation, and apoptosis. NLRP3 inflammasome and glycolysis in murine lung tissues challenged with LPS were also blocked by Peficitinib. Furthermore, we found that the activation of JAK3/signal transducer and activator of transcription 3 (STAT3) was also suppressed by Peficitinib in mice with ALI. However, in Jak3 knockout mice, Peficitinib did not show obvious protective effects after LPS injection. In vitro experiments further showed that Jak3 overexpression completely abolished Peficitinib-elicited inhibitory effects on pyroptosis and glycolysis in LPS-induced RAW264.7 macrophages. Finally, we unveiled that LPS-induced activation of JAK3/STAT3 was mediated by toll-like receptor 4 (TLR4) in RAW264.7 macrophages. Collectively, our study proved that Peficitinib could protect against ALI by blocking JAK3-mediated glycolysis and pyroptosis in macrophages, which may serve as a promising candidate against ALI in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Inhibition of Janus kinase 3 (JAK3), a member of the JAK family of tyrosine kinases, remains an essential area of research for developing treatments for autoimmune diseases, particularly cancer and rheumatoid arthritis. The recent discovery of a new JAK3 protein, PDB ID: 4Z16, offers exciting possibilities for developing inhibitors capable of forming a covalent bond with the Cys909 residue, thereby contributing to JAK3 inhibition. A powerful prediction model was constructed and validated using Monte Carlo methods, employing various internal and external techniques. This approach resulted in the prediction of eleven new molecules, which were subsequently filtered to identify six compounds exhibiting potent pIC 50 values. These candidates were then subjected to ADMET analysis, molecular docking (including reversible-reversible docking with tofacitinib, an FDA-approved drug, and reversible-irreversible docking for the newly designed compounds), molecular dynamics (MD) analysis for 300 ns, and calculation of free binding energy. The results suggested that these compounds hold promise as JAK3 inhibitors. In summary, the new compounds have exhibited favorable outcomes compared to other compounds across various modeling approaches. The collective findings from these investigations provide valuable insights into the potential therapeutic applications of covalent JAK3 inhibitors, offering a promising direction for the development of novel treatments for autoimmune disorders.Communicated by Ramaswamy H. Sarma.

Introduction: JAK3 kinase inhibitor has become an effective means to treat tumors and autoimmune diseases., Methods: In this study, molecular docking and molecular dynamics simulation were used to study the theoretical interaction mechanism between 1-phenylimidazolidine-2-one molecules and JAK3 protein., Results: The results of molecular docking showed that the six 1-phenylimidazolidine-2-one derivatives obtained by virtual screening were bound to the ATP pocket of JAK3 kinase, which were competitive inhibitors of ATP, and were mainly bound to the pocket through hydrogen bonding and hydrophobic interaction. Further, MM/GBSA based on molecular dynamics simulation sampling was used to calculate the binding energy between six molecules and the JAK3 kinase protein. Subsequently, the binding energy was decomposed into the contribution of each amino acid residue, of which Leu905, Lys855, Asp967, Leu956, Tyr904, and Val836 were the main energycontributing residues. Among them, the molecule numbered LCM01415405 can interact with the specific amino acid Arg911 of JAK3 kinase, suggesting that the molecule may be a selective JAK3 kinase inhibitor. The root-mean-square fluctuation (RMSF) of JAK3 kinase pocket residues during molecular dynamics simulation showed that the combination of six new potential small molecule inhibitors with JAK3 kinase could reduce the flexibility of JAK3 kinase pocket residues., Conclusion: These findings reveal the mechanism of 1-phenylimidazolidine-2-one derivatives on JAK3 protein and provide a relatively solid theoretical basis for the development and structural optimization of JAK3 protein inhibitors., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Rheumatoid arthritis (RA) remains one of the most prevalent autoimmune diseases worldwide. Janus kinase 3 (JAK3) is an essential enzyme for treating autoimmune diseases, including RA. Molecular modeling techniques play a crucial role in the search for new drugs by reducing time delays. In this study, the 3D-QSAR approach is employed to predict new JAK3 inhibitors. Two robust models, both field-based with R 2 = 0.93, R = 0.96, and Q 2 = 87, and atom-based with R 2 = 0.94, R = 0.97, and Q 2 = 86, yielded good results by identifying groups that may readily direct their interaction. A reliable pharmacophore model, DHRRR1, was provided in this work to enable the clear characterization of chemical features, leading to the design of 13 inhibitors with their pIC 50 values. The DHRRR1 model yielded a validation result with a ROC value of 0.87. Five promising inhibitors were selected for further study based on an ADMET analysis of their pharmacokinetic properties and covalent docking (CovDock). Compared to the FDA-approved drug tofacitinib, the pharmaceutical features, binding affinity and stability of the inhibitors were analyzed through CovDock, 300 ns molecular dynamics simulations, free energy binding calculations and ADMET predictions. The results show that the inhibitors have strong binding affinity, stability and favorable pharmaceutical properties. The newly predicted molecules, as JAK3 inhibitors for the treatment of RA, are promising candidates for use as drugs.

Background: The keloid treatment is still a thorny and complicated clinical problem, especially in multiple keloids induced by wound, severe burn, ethnic background or cultural behaviors, or unexplained skin healing. Mainstream treatments have limited efficacy in treating multiple keloids. As no oral treatment with painlessness and convenience is available, oral treatment strategies should be formulated., Objectives: This study aimed to investigate the efficacy and therapeutic mechanism of oral tofacitinib in keloid patients., Methods: We recruited the 7 patients with keloid scars and prescribed 5 mg of tofacitinib twice a day orally with a maximum follow-up of 12 weeks. The Patient and Observer Scar Assessment Scale (POSAS), the Vancouver scar scale (VSS), ANTERA 3D camera, and the DUB Skin Scanner 75 were used to assess the characteristics of the lesion. Immunohistochemistry was performed to evaluate collagen synthesis, proliferation, and relative molecular pathways. Moreover, the effects of tofacitinib were assessed on keloid fibroblast in vitro., Results: After 12 weeks of oral tofacitinib, significant improvement in POSAS, VSS, and Dermatology Life Quality Index (DLQI) scores was observed (p &lt; 0.05). The volume, lesion height, and dermis thickness of the keloid decreased (p &lt; 0.05). Moreover, significant decreases in the expression of collagen I, Ki67, p-STAT 3, and p-SMAD2 were observed after 12 weeks of administration. In vitro experiments suggested that tofacitinib treatment inhibits fibroblast proliferation and collagen I synthesis via suppression of STAT3 and SMAD2 pathway., Conclusion: Tofacitinib, a new candidate oral drug for keloid, could reduce keloid lesion volume by inhibiting collagen synthesis and inhibiting fibroblast proliferation, and alleviate itch and pain to obtain a better life quality., (© 2023 S. Karger AG, Basel.)

Alopecia areata (AA) is an autoimmune disease caused by T cell-mediated destruction of the hair follicle (HF). Therefore, approaches that effectively disrupt pathogenic T cell responses are predicted to have therapeutic benefit for AA treatment. T cells rely on the duality of T cell receptor (TCR) and gamma chain (γc) cytokine signaling for their development, activation, and peripheral homeostasis. Ifidancitinib is a potent and selective next-generation JAK1/3 inhibitor predicted to disrupt γc cytokine signaling. We found that Ifidancitinib robustly induced hair regrowth in AA-affected C3H/HeJ mice when fed with Ifidancitinib in chow diets. Skin taken from Ifidancitinib-treated mice showed significantly decreased AA-associated inflammation. CD44 + CD62L - CD8 + T effector/memory cells, which are associated with the pathogenesis of AA, were significantly decreased in the peripheral lymphoid organs in Ifidancitinib-treated mice. We observed high expression of co-inhibitory receptors PD-1 on effector/memory CD8 + T cells, together with decreased IFN-γ production in Ifidancitinib-treated mice. Furthermore, we found that γc cytokines regulated T cell exhaustion. Taken together, our data indicate that selective induction of T cell exhaustion using a JAK inhibitor may offer a mechanistic explanation for the success of this treatment strategy in the reversal of autoimmune diseases such as AA., Competing Interests: Columbia University has licensed patents on the use of JAK inhibitors in alopecia areata to Aclaris Therapeutics, Inc. AC is a consultant to Almirall, Janssen Arcturus and a shareholder of Aclaris Therapeutics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dai, Sezin, Chang, Lee, Wang and Christiano.)

Terminal T-cell exhaustion poses a significant barrier to effective anticancer immunotherapy efficacy, with current drugs aimed at reversing exhaustion being limited. Recent investigations into the molecular drivers of T-cell exhaustion have led to the identification of chronic IL2 receptor (IL2R)-STAT5 pathway signaling in mediating T-cell exhaustion. We targeted the key downstream IL2R-intermediate JAK 3 using a clinically relevant highly specific JAK3-inhibitor (JAK3i; PF-06651600) that potently inhibited STAT5-phosphorylation in vitro. Whereas pulsed high-dose JAK3i administration inhibited antitumor T-cell effector function, low-dose chronic JAK3i significantly improved T-cell responses and decreased tumor load in mouse models of solid cancer. Low-dose JAK3i combined with cellular and peptide vaccine strategies further decreased tumor load compared with both monotherapies alone. Collectively, these results identify JAK3 as a novel and promising target for combination immunotherapy., (©2022 American Association for Cancer Research.)

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.

The idea of using ranked binding energies of residues and data fusion are presented here for the first time as a valuable tool to classify active and selective inhibitors. Selective inhibitors of JAK3 can inhibit inflammatory cytokine while preventing targeting other subtypes of JAK1 and JAK2. Herein, we report a novel way to identify both active JAK3 and selective JAK1/JAK3 and JAK2/JAK3 inhibitors using the effective activity and selectivity classifications. The most important residues (top 10) responsible for the inhibition mechanism are sorted from high to low energies, which are considered as variables in the classification process. In addition, the ranked energies of ligands' heteroatoms (top 5), ranked energies of hydrogen bonds (top 5) and important molecular descriptors (top 10) were used to construct different data fusion possibilities. It is shown that the proposed data fusion strategy can increase the accuracy of the activity classification to 100% and the selectivity classification to 96.4%. The proposed strategies represented in this paper can help medicinal or pharmaceutical chemist in evaluation of both active and selective inhibitors before synthesizing new pharmaceuticals.

An aromatic trifluoromethyl ketone moiety was characterized as a new warhead for covalently reversible kinase inhibitor design to target the non-catalytic cysteine residue. Potent and selective covalently reversible inhibitors of FGFR4 kinase were successfully designed and synthesized by utilizing this new warhead. The binding mode of a representative inhibitor was fully characterized by using multiple technologies including MALDI-TOF mass spectrometry, dialysis assay and X-ray crystallographic studies etc. This functional group was also successfully applied to discovery of a new JAK3 inhibitor, suggesting its potential application in designing other kinase inhibitors., (Copyright © 2021. Published by Elsevier Ltd.)

A series of cyano-substituted 2,4-diarylaminopyrimidines was designed and synthesized as potent non-covalent JAK3 inhibitors. Among the derivatives synthesized, 9o (IC 50  = 22.86 nM), 9 k (IC 50  = 21.58 nM), and 9j (IC 50  = 20.66 nM) demonstrated inhibitory potencies against JAK3 similar to the known JAK3 inhibitor tofacitinib (IC 50  = 20.10 nM). Moreover, 9o displayed potent anti-proliferative activities against Raji and Ramos cells, with IC 50 values of 0.9255 μM and 1.405 μM, respectively. In addition, 9o demonstrated low toxicity in normal HBE (human bronchial epithelial cells, IC 50  > 10 μΜ) and L-02 (human liver cells, IC 50  = 3.104 μΜ) cells. Analysis of the mode of action by flow cytometry indicated that 9o effectively arrested Raji cells at the G2/M phase. Taken together, these results suggested that 9o might be a promising candidate for development as a potential treatment for B-cell lymphoma., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) are key intracellular mediators in the signal transduction of many cytokines and growth factors. Common γ chain cytokines and interferon-γ that use the JAK/STAT pathway to induce biological responses have been implicated in the pathogenesis of alopecia areata (AA), a T cell-mediated autoimmune disease of the hair follicle. We previously showed that therapeutic targeting of JAK/STAT pathways using the first-generation JAK1/2 inhibitor, ruxolitinib, and the pan-JAK inhibitor, tofacitinib, was highly effective in the treatment of human AA, as well as prevention and reversal of AA in the C3H/HeJ mouse model. To better define the role of individual JAKs in the pathogenesis of AA, in this study, we tested and compared the efficacy of several next-generation JAK-selective inhibitors in the C3H/HeJ mouse model of AA, using both systemic and topical delivery. We found that JAK1-selective inhibitors as well as JAK3-selective inhibitors robustly induced hair regrowth and decreased AA-associated inflammation, whereas several JAK2-selective inhibitors failed to restore hair growth in treated C3H/HeJ mice with AA. Unlike JAK1, which is broadly expressed in many tissues, JAK3 expression is largely restricted to hematopoietic cells. Our study demonstrates inhibiting JAK3 signaling is sufficient to prevent and reverse disease in the preclinical model of AA.

Recent years have seen a resurgence in drug discovery efforts aimed at the identification of covalent inhibitors which has led to an explosion of literature reports in this area and most importantly new approved therapies. These reports and breakthroughs highlight the significant investments made across the industry in SAR campaigns to optimize inhibitors. The potency of covalent inhibitors is generally considered to be more accurately described by the time-independent kinetic parameter k inact /K i rather than a by a simple IC 50 since the latter is a time-dependent parameter. Enzyme substrate concentrations are an additional important factor to consider when attempting to translate parameters derived from enzymology experiments to phenotypic behavior in a physiologically relevant cell-based system. Theoretical and experimental investigations into the relationship between IC 50 , time, substrate concentration and K inact /K i provided us with an effective approach to provide meaningful data for SAR optimization. The data we generated for our JAK3 irreversible covalent inhibitor program using IC 50 values provided by enzyme assays with long incubations (>1h) coupled with physiological substrate concentration provided the medicinal chemist with optimal information in a rapid and efficient manner. We further document the wide applicability of this method by applying it to other enzymes systems where we have run covalent inhibitor programs., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Targeted covalent inhibitors represent a viable strategy to block protein kinases involved in different disease pathologies. Although a number of computational protocols have been published for identifying druggable cysteines, experimental approaches are limited for mapping the reactivity and accessibility of these residues. Here, we present a ligand based approach using a toolbox of fragment-sized molecules with identical scaffold but equipped with diverse covalent warheads. Our library represents a unique opportunity for the efficient integration of warhead-optimization and target-validation into the covalent drug development process. Screening this probe kit against multiple kinases could experimentally characterize the accessibility and reactivity of the targeted cysteines and helped to identify suitable warheads for designed covalent inhibitors. The usefulness of this approach has been confirmed retrospectively on Janus kinase 3 (JAK3). Furthermore, representing a prospective validation, we identified Maternal embryonic leucine zipper kinase (MELK), as a tractable covalent target. Covalently labelling and biochemical inhibition of MELK would suggest an alternative covalent strategy for MELK inhibitor programs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Five new nitrogen-containing compounds (1-3, 5, and 6), two compounds which was firstly isolated from natural origin (7 and 10), along with six known ones, were isolated from the ethanol extract of the whole bodies of Polyphaga plancyi. The structures of the new compounds including their absolute configurations at stereogenic centers were assigned on the basis of spectroscopic analyses and computational methods. Racemic 10 was separated by chiral HPLC. Biological activities of these isolates against extracellular matrix components in rat renal proximal tubular cells, EV71, COX-2, ROCK2, JAK3, and tuberculosis were evaluated. Importantly, 8 was found to be a selective Smad3 phosphorylation inhibitor., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Tofacitinib is a partially selective Janus kinase inhibitor approved for the treatment of refractory moderate to severe ulcerative colitis [UC]. We sought to define the effectiveness and adverse effects of tofacitinib in a real-world cohort., Methods: We conducted a retrospective observational cohort study of 134 patients with UC [64% male; median age 37 years [range 16-81]; 83% of patients had previously received at least one biologic] treated with tofacitinib from October 2018 to October 2019 in four UK centres. Disease activity was assessed using the Simple Clinical Colitis Activity Index [SCCAI] or partial Mayo score [PMS], depending on study site. Response and remission were defined as a reduction in SCCAI or PMS of ≥3and SCCAI ≤2 or a PMS ≤1, respectively., Results: Overall, 74% (88/119; 95 confidence interval [CI] 65-81%] patients responded to tofacitinib at Week 8 and steroid-free remission was observed in 44% [47/108; 95% CI 3453%] patients at Week 26. Primary non-response was independently associated with younger age [p = 0.014] and higher C-reactive protein [CRP] levels at baseline [p = 0.004]. Only 23% [3/13] of patients who continued tofacitinib in the setting of primary non-response were in steroid-free remission at Week 26. Prior biologic exposure did not influence response or remission rates. Dose escalation, however, recaptured response in approximately half of patients who had lost response. Dyslipidaemia was observed in 20% [27/134; 95% CI 1428%] of patients, but adverse events necessitating drug withdrawal were uncommon and no venous thromboembolic events occurred., Conclusions: In this multicentre real-world cohort, tofacitinib was well tolerated and clinically effective in a treatment-refractory UC population., (© The Author(s) 2020. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To evaluate the efficacy and safety of PF-06651600 (ritlecitinib), an irreversible inhibitor of JAK3 and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family, in comparison with placebo in patients with rheumatoid arthritis (RA)., Methods: An 8-week, phase II, double-blind, parallel-group study was conducted. Seventy patients who were seropositive for anti-citrullinated protein antibodies and/or rheumatoid factor were randomized 3:2 to receive oral PF-06651600 (200 mg once daily) or placebo for 8 weeks. Eligible patients had an inadequate response to methotrexate, and the study design allowed up to 50% of patients to have previously received 1 tumor necrosis factor inhibitor that was inadequately effective and/or not tolerated. The primary end point was change from baseline in the Simplified Disease Activity Index (SDAI) score at week 8, assessed by Bayesian analysis using an informative prior distribution for placebo response., Results: Mean change from baseline in the SDAI score at week 8 was greater in the PF-06651600 group (-26.1 [95% credible interval -29.7, -22.4]) than in the placebo group (-16.8 [95% credible interval -20.9, -12.7]; P < 0.001). Most adverse events (AEs) were mild in severity, and no treatment-related serious AEs, severe AEs, or deaths were reported. The most common classes of AE were infections and infestations as well as skin and subcutaneous tissue disorders; there was 1 mild case of herpes simplex in the PF-06651600 group that was considered to be treatment related, which resolved within 3 days without study treatment discontinuation or antiviral therapy., Conclusion: Treatment with the oral JAK3/TEC inhibitor PF-06651600 (200 mg once daily) was associated with significant improvements in RA disease activity and was generally well-tolerated in this small 8-week study., (© 2020 Pfizer Inc. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

The traditional Chinese medicinal herb Notopterygium incisum Ting ex H.T. Chang has anti-rheumatism activity, and a mass spectrometry assay of patients' serum after administration of the herb revealed that notopterol is the most abundant component enriched. However, the functions of notopterol and its molecular target in rheumatoid arthritis (RA) treatment remain unknown. Here, we show in different RA mouse strains that both oral and intraperitoneal administration of notopterol result in significant therapeutic effects. Mechanistically, notopterol directly binds Janus kinase (JAK)2 and JAK3 kinase domains to inhibit JAK/signal transducers and activators of transcription (JAK-STAT) activation, leading to reduced production of inflammatory cytokines and chemokines. Critically, combination therapy using both notopterol and tumor necrosis factor (TNF) blocker results in enhanced therapeutic effects compared to using TNF blocker alone. We demonstrate that notopterol ameliorates RA pathology by targeting JAK-STAT signaling, raising the possibility that notopterol could be effective in treating other diseases characterized by aberrant JAK-STAT signaling pathway., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Gain- or loss-of-function mutations in Janus kinase 3 (JAK3) contribute to the pathogenesis of various haematopoietic malignancies and immune disorders, suggesting that aberrant JAK3 signalling is an attractive therapeutic target to treat these disorders. In this study, we performed structure-based computational database screening using the 3D structure of the JAK3 kinase domain and the National Cancer Institute diversity set and identified tubulosine as a novel JAK3 inhibitor. Tubulosine directly blocked the catalytic activity of JAK3 by selective interacting with the JAK3 kinase domain. Consistently, tubulosine potently inhibited persistently activated and interleukin-2-dependent JAK3, and JAK3-mediated downstream targets. Importantly, it did not affect the activity of other JAK family members, particularly prolactin-induced JAK2/signal transducer and activator of transcription 5 and interferon alpha-induced JAK1-TYK2/STAT1. Tubulosine specifically decreased survival and proliferation of cancer cells, in which persistently active JAK3 is expressed, by inducing apoptotic and necrotic/autophagic cell death without affecting other oncogenic signalling. Collectively, tubulosine is a potential small-molecule compound that selectively inhibits JAK3 activity, suggesting that it may serve as a promising therapeutic candidate for treating disorders caused by aberrant activation of JAK3 signalling., (© 2020 The Authors. Journal of Cellular and Molecular Medicine. published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

With a resurgence in interest in covalent drugs, there is a need to identify new moieties capable of cysteine bond formation that are differentiated from commonly employed systems such as acrylamide. Herein, we report on the discovery of new alkynyl benzoxazine and dihydroquinazoline moieties capable of covalent reaction with cysteine. Their utility as alternative electrophilic warheads for chemical biological probes and drug molecules is demonstrated through site-selective protein modification and incorporation into kinase drug scaffolds. A potent covalent inhibitor of JAK3 kinase was identified with superior selectivity across the kinome and improvements in in vitro pharmacokinetic profile relative to the related acrylamide-based inhibitor. In addition, the use of a novel heterocycle as a cysteine reactive warhead is employed to target Cys788 in c-KIT, where acrylamide has previously failed to form covalent interactions. These new reactive and selective heterocyclic warheads supplement the current repertoire for cysteine covalent modification while avoiding some of the limitations generally associated with established moieties.

Selective inhibition of janus kinase (JAK) has been identified as an important strategy for the treatment of autoimmune disorders. Optimization at the C2 and C4-positions of pyrimidine ring of Cerdulatinib led to the discovery of a potent and orally bioavailable 2,4-diaminopyrimidine-5-carboxamide based JAK3 selective inhibitor (11i). A cellular selectivity study further confirmed that 11i preferentially inhibits JAK3 over JAK1, in JAK/STAT signaling pathway. Compound 11i showed good anti-arthritic activity, which could be correlated with its improved oral bioavailability. In the repeat dose acute toxicity study, 11i showed no adverse changes related to gross pathology and clinical signs, indicating that the new class JAK3 selective inhibitor could be viable therapeutic option for the treatment of rheumatoid arthritis., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Selective JAK3 inhibitors have been shown to have a potential benefit in the treatment of autoimmune disorders. Here we report the identification of a series of pyrazolopyrimidine derivatives as potent JAK3 inhibitors that exploit a unique cysteine (Cys909) residue in JAK3. Most of these compounds (13k, 13n and 13 t), displayed stronger anti-JAK3 kinase activity and selectivity than tofacitinib. Furthermore, the most active inhibitor 13t (IC 50  = 0.1 nM), also exhibited favourable selectivity for JAK3 in a panel of 9 kinases which contain the same cysteine. In a series of cytokinestimulated cellular analysis, compound 13 t, could potently block the JAK3-STAT signaling pathway. Further biological studies, including cellular antiproliferative activity assays and a rat adjuvant-induced arthritis model for in vivo evaluation, also indicated its efficacy and low toxicity in the treatment of rheumatoid arthritis. The results of these experimental explorations suggested that 13t is a promising lead compound for the development of selective JAK3 inhibitor with therapeutic potential in rheumatoid arthritis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

As non-receptor tyrosine kinases, Janus kinases (JAKs) have become an attractive target for the treatment of autoimmune diseases and cancers. JAKs play a pivotal role in innate immunity, inflammation, and hematopoiesis by mediating the signaling of numerous cytokines, growth factors, and interferons (IFNs). Selective inhibitors of a variety of JAK members are expected to inhibit pro-inflammatory cytokine-mediated inflammation and immune responses, while preventing targeting other subtypes of JAKs. In this work, poorly selective compounds based on 4- or 6-phenyl-pyrimidine derivatives have been improved to highly potent and selective compounds by designing a covalent binding tether, which attaches to the unique cysteine (Cys909) residue in JAK3. Compound 12 exhibited potent JAK3 inhibitory activity (IC 50  = 1.7 nM) with an excellent selectivity profile when compared to the other JAK isoforms (>588-fold). In a cellular assay, compound 12 strongly inhibited JAK3-dependent signaling and T cell proliferation. Moreover, in vivo data revealed that compound 12 significantly suppressed oxazolone (OXZ)-induced delayed hypersensitivity responses in Balb/c mice. Compound 12 also displayed decent pharmacokinetic properties and was suitable for in vivo use. Taken together, these results indicated that compound 12 may be a promising tool compound as a selective JAK3 inhibitor for treating autoimmune diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

A new class of pyrimidine derivatives were identified as potent protein tyrosine kinase (PTK) inhibitors for the treatment of idiopathic pulmonary fibrosis (IPF). Most of these small-molecule inhibitors displayed strong enzymatic activity against BTK and JAK3 kinases at concentrations lower than 10 nM. The representative compound N-(3-((5-chloro-2-(4-((1-morpholino)acetylamino)phenylamino)-4-pyrimidinyl)amino)phenyl)acrylamide (6 a) also exhibited high inhibitory potency toward both BTK and JAK kinase families, as well as ErbB4, at a concentration of 10 nM, achieving rates of inhibition higher than 57 %. Additionally, in vivo biological evaluations showed that 6 a can remarkably decrease the severity of IPF disease. All these investigations suggested that the multi-PTK inhibitor 6 a may serve as a promising agent for the treatment of IPF., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bruton's tyrosine kinase (BTK) and Janus kinase 3 (JAK3) are very promising targets for hematological malignancies and autoimmune diseases. In recent years, a few compounds have been approved as a marketed medicine, and several are undergoing clinical trials. By recombining the dominant backbone of known active compounds, constructing a foused library, and screening a broad panel of kinases, we found a class of compounds with dual activities of anti-BTK and anti-JAK3. Some of the compounds have shown 10-folds more active in the enzyme and cell-based assays than a known active compound. Furthermore, liver microsome stability experiments show that these compounds have better stability than ibrutinib. These explorations offered new clues to discover benzoxaborole fragment and pyrimidine scaffold as more effective BTK and JAK3 dual inhibitors., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Idiopathic pulmonary fibrosis (IPF) is a serious and fatal lung disease, with a median survival of only 3-5 years from diagnosis. Janus kinase 3 (JAK3) has a well-established role in the pathogenesis of various autoimmune diseases, including rheumatoid arthritis (RA) and autoimmune-related pulmonary fibrosis. In this study, through the use of a conformationally-constrained design strategy, a series of thieno[3,2-d]pyrimidines were synthesized as potent JAK3 inhibitors for the treatment of IPF. Among them, the most potent JAK3 inhibitor, namely 8e (IC 50  = 1.38 nM), significantly reduced the degree of airsacculitis and fibrosis according to hematoxylin-eosin (HE) staining assay for the lung tissue in the bleomycin (BLM)-induced pulmonary fibrosis mouse model. The clear reduction of the lung collagen deposition by the determination of Masson and hydroxyproline (HYP) content also demonstrated its efficacy in the treatment of fibrosis. In addition, 8e also reduced the expression of the inflammatory markers IL-6, IL-17A, TNF-α and malondialdehyde (MDA) in lung tissue, which indicated its higher anti-inflammatory activity compared with that of the reference agents (nintedanib and gefitinib). Furthermore, it possessed low cytotoxicity against normal human bronchial epithelia (HBE) cells (IC 50  > 39.0 μM) and C57BL mice. All these evaluated biological properties suggest that 8e may be a potential JAK3 inhibitor for the treatment of IPF., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

JAK3 is predominantly expressed in hematopoietic cells and has been a promising therapeutic target for the treatment of B-cell lymphoma. In this study, a new class of thieno[3,2-d]pyrimidines harboring acrylamide pharmacophore were synthesized as potent covalent JAK3 inhibitors (IC 50  < 10 nM). Among them, 9a and 9 g displayed the strongest inhibitory potency against JAK3 kinase activity, with IC 50 values of 1.9 nM and 1.8 nM, respectively. Furthermore, compared with the reference agents, Spebrutinib and Ibrutinib, 9a not only demonstrated enhanced antiproliferative activity against B lymphoma cells, but also showed very weak proliferative inhibition against normal peripheral blood mononuclear cells (PBMCs) at a concentration of 20 μM. Analysis of the mechanism revealed that 9a could induce the obvious apoptosis in B lymphoma cells and prevent JAK3-STAT3 cascade as well as BTK pathway. Taken together, 9a may be served as a potential new JAK3 inhibitor for the treatment of B-cell lymphoma., Competing Interests: Declaration of Competing Interest We want to submit the revised manuscript in the category of research articles titled “JAK3 inhibitors based on thieno[3,2-d]pyrimidine scaffold: design, synthesis and bioactivity evaluation for the treatment of B-cell lymphoma”. There are no concerns about third-party copyright or conflicts of interest or online supplementary material., (Copyright © 2019. Published by Elsevier Inc.)

Rheumatoid arthritis (RA) is a representative autoimmune disease characterized by chronic inflammation and joint destruction. Although biological inhibitors such as TNF-α and IL-6 antibodies have achieved success in clinical therapy, small molecule inhibitors against the Janus kinases (JAKs) involved in the signaling pathways of various cytokine receptors have gained more attraction as safe and efficacious options. In this study, we identified CS12192 as a novel selective JAK3/JAK1/TBK1 inhibitor and investigated its pharmacological effects on the experimental arthritis models in rat and mouse. We found that CS12192 showed a more selective inhibitory activity on JAK3, and to a less extent on JAK1 and TBK1, that were verified by decreased activation of p-STATs and p-IRF3 as well as down-regulation of IFN gene expression in the cultured cells with relevant stimuli. Furthermore, oral treatment with CS12192 dose-dependently ameliorated the disease severity, hind paw swelling, body weight loss, and bone destruction in rat models of adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA). In a mouse CIA model, CS12192 also attenuated the disease severity, which was correlated with the suppressed CD4 + T cell activation and Th17 function, as well as the reduced cytokine levels in sera and pro-inflammatory cytokine and chemokine gene expression in joint tissue. Corroboratively, RANKL-induced osteoclast formation was inhibited by CS12192. Thus, these results suggest that CS12192 as a novel selective JAK inhibitor has therapeutic potential for the treatment of RA and may provide a new strategy for the control of autoimmune diseases., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Breast cancer resistance protein (BCRP) is a member of ATP-binding cassette (ABC) transporter proteins whose primary function is to efflux substrates bound to the plasma membrane. Impaired intestinal barrier functions play a major role in chronic low-grade inflammation (CLGI)-associated obesity, but the regulation of BCRP during obesity and its role in maintaining the intestinal barrier function during CLGI-associated obesity are unknown. In the present study, using several approaches, including efflux assays, immunoprecipitation, immunoblotting, immunohistochemistry, paracellular permeability assay, FACS, cytokine assay, and immunofluorescence microscopy, we report that obese individuals have compromised intestinal BCRP functions and that diet-induced obese mice recapitulate these outcomes. We demonstrate that the compromised BCRP functions during obesity are because of loss of Janus kinase 3 (JAK3)-mediated tyrosine phosphorylation of BCRP. Our results indicate that JAK3-mediated phosphorylation of BCRP promotes its interactions with membrane-localized β-catenin essential not only for BCRP expression and surface localization, but also for the maintenance of BCRP-mediated intestinal drug efflux and barrier functions. We observed that reduced intestinal JAK3 expression during human obesity or JAK3 knockout in mouse or siRNA-mediated β-catenin knockdown in human intestinal epithelial cells all result in significant loss of intestinal BCRP expression and compromised colonic drug efflux and barrier functions. Our results uncover a mechanism of BCRP-mediated intestinal drug efflux and barrier functions and establish a role for BCRP in preventing CLGI-associated obesity both in humans and in mice., (© 2019 Mishra et al.)

PF-06651600 was developed as an irreversible inhibitor of JAK3 with selectivity over the other three JAK isoforms. A high level of selectivity toward JAK3 is achieved by the covalent interaction of PF-06651600 with a unique cysteine residue (Cys-909) in the catalytic domain of JAK3, which is replaced by a serine residue in the other JAK isoforms. Importantly, 10 other kinases in the kinome have a cysteine at the equivalent position of Cys-909 in JAK3. Five of those kinases belong to the TEC kinase family including BTK, BMX, ITK, RLK, and TEC and are also inhibited by PF-06651600. Preclinical data demonstrate that inhibition of the cytolytic function of CD8 + T cells and NK cells by PF-06651600 is driven by the inhibition of TEC kinases. On the basis of the underlying pathophysiology of inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, alopecia areata, and vitiligo, the dual activity of PF-06651600 toward JAK3 and the TEC kinase family may provide a beneficial inhibitory profile for therapeutic intervention.

Janus kinases (JAKs) play a key role in the proliferation, apoptosis and differentiation of immune cells, and JAKs are considered as an attractive target for the treatment of inflammatory and autoimmune diseases. Here we show the design and optimization of pyrimidine-4,6-diamine derivatives as selectivity JAK3 inhibitors. Compound 11e, which might interact with unique cysteine (Cys909) residue in JAK3, exhibited excellent JAK3 inhibitory activity (IC 50  = 2.1 nM) and high JAK kinase selectivity. In cellular assay, 11e showed moderate potency inhibiting IL-2-stimulated T cell proliferation. The data supports the further development of novel JAKs inhibitors., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, the thermodynamic dissociation constant (pK a ) values of tofacitinib in acetonitrile-water binary mixtures with of 25%, 30%, 35% and 45% (v/v) have been determined at 25-45 °C range of temperatures with reversed-phase liquid chromatography (RPLC). The chromatographic determination was achieved on a Kinetex Core-Shell EVO C18-Phenomenex (150 mm x 4.6 mm, 5 μm) analytical column. For each case pK a values and retention factors of tofacitinib by taking into account the effect of the activity coefficients in hydro-organic water-acetonitrile binary mixtures have been evaluated and which obtain by SOLVER algorithm of spreadsheet program Excel to fit experimental data to the nonlinear expression derived. From these values, the thermodynamic aqueous pK a value of the drug was calculated by different approaches. Thermodynamic parameters standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) derived from dissociation constant measurements at six different temperatures were calculated by from linearity plots of IogK a against 1/T (van't Hoff plot)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

JAK family kinases are important mediators of immune cell signaling and Janus Kinase 3 (JAK3) has long been indicated as a potential target for autoimmune disorders. Intensive efforts to develop highly selective JAK3 inhibitors have been underway for many years. However, because of JAK3's strong binding preference to adenosine 5'-triphosphate (ATP), a number of inhibitors exhibit large gaps between enzymatic and cellular potency, which hampers efforts to dissect the roles of JAK3 in cellular settings. Using a targeted covalent inhibitor approach, we discovered compound 32, which overcame ATP competition (1 mM) in the enzymatic assay, and demonstrated significantly improved inhibitory activity for JAK3-dependent signaling in mouse CTLL-2 and human peripheral blood mononuclear cells. Compound 32 also exhibited high selectivity within the JAK family and good pharmacokinetic properties. Thus, it may serve as a highly valuable tool molecule to study the overlapping roles of JAK family kinases in complex biological settings. Our study also suggested that for covalent kinase inhibitors, especially those targeting kinases with low K m ATP values, the reversible interactions between molecules and proteins should be carefully optimized to improve the overall potency.

The search for inhibitors of the Janus kinase family (JAK1, JAK2, JAK3 and TYK2) has been ongoing for several decades and has resulted in a number of JAK inhibitors being approved for use in patients, such as tofacitinib for the treatment of autoimmune diseases such as Rheumatoid Arthritis (RA). Although initially thought to be a JAK3 selective inhibitor, tofacitinib was subsequently found to possess significant activity to inhibit JAK1 and JAK2 which has contributed to some adverse side effects. A selective JAK3 inhibitor should only have an effect within the immune system since JAK3 is solely expressed in lymphoid tissue; this makes JAK3 a target of interest in the search for treatments of autoimmune diseases. A method to obtain selectivity for JAK3 over the other JAK family members, which has attracted more scientific attention recently, is the targeting of the active site cysteine residue, unique in JAK3 within the JAK family, with compounds containing electrophilic warheads which can form a covalent bond with the nucleophilic thiol of the cysteine residue. This review encompasses the historical search for a covalent JAK3 inhibitor and the most recently published research which hasn't been reviewed to date. The most important compounds from the publications reviewed the activity and selectivity of these compounds together with some of the more important biological results are condensed in to an easily digested form that should prove useful for those interested in the field., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Islet transplantation is efficacious to prevent severe hypoglycemia and glycemic liability of selected patients of type 1 diabetes. However, since calcineurin inhibitor (CNI) causes β-cell and nephrotoxicity, alternative drug(s) with similar potency and safety profile to CNI will be highly desirable. Here we tested whether JAK3 inhibitor, tofacitinib could be used instead of tacrolimus in CIT07 immunosuppression regimen in cynomolgus nonhuman primate (NHP) model. Five independent streptozotocin (STZ)-induced diabetic monkeys were transplanted with MHC-mismatched allogeneic islets and three animals were further re-transplanted upon insufficient glycemic control or early islet graft rejection. After islet transplantation, blood glucose levels were quickly stabilized and maximal islet graft survival as measured by serum C-peptide concentration was >330, 98, >134, 31, or 22 days, respectively, after transplantation (median survival day; 98 days). Cellular and humoral immune responses were efficiently suppressed by JAK3 inhibitor-based immunosuppression during the follow-up periods. Although intermittent increases of the genome copy number of cynomolgus cytomegalovirus (CMV) were detected by quantitative real-time PCR analyses, serious infections or posttransplant lymphoproliferative disease (PTLD) was not found in all animals. Taken together, we have shown that JAK3 inhibitor could be used in replacement of tacrolimus in a highly translatable NHP islet transplantation model and these results suggest that JAK3 inhibitor will be potentially incorporated in human allogeneic islet transplantation.