RuBi-Ruxolitinib: A Photoreleasable Antitumor JAK Inhibitor.

We describe the synthesis and biological testing of ruthenium-bipyridine ruxolitinib (RuBiRuxo), a photoreleasable form of ruxolitinib, a JAK inhibitor used as an antitumoral agent in cutaneous T-cell lymphomas (CTCL). This novel caged compound is synthesized efficiently, is stable in aqueous solution at room temperature, and is photoreleased rapidly by visible light. Irradiation of RuBiRuxo reduces cell proliferation and induces apoptosis in a light- and time-dependent manner in a CTCL cell line. This effect is specific and is mediated by a decreased phosphorylation of STAT proteins. Our results demonstrate the potential of ruthenium-based photocompounds and light-based therapeutic approaches for the potential treatment of cutaneous lymphomas and other pathologies.

Electrochemical Behavior of Janus Kinase Inhibitor Ruxolitinib at a Taurine-Electropolymerized Carbon Paste Electrode: Insights into Sensing Mechanisms.

Ruxolitinib (RXL) is a Janus kinase inhibitor used for treating intermediate- or high-risk myelofibrosis. This study presents an electrode modified with electrochemically polymerized taurine on a carbon paste electrode via cyclic voltammetry (CV). The surface characterization of the poly(taurine)-CP electrode was evaluated by using electrochemical (electrochemical impedance spectroscopy─EIS, CV), morphological (scanning electron microscope─SEM), and spectroscopic (Fourier-transform infrared spectroscopy─FT-IR) techniques. Under optimized conditions, RXL exhibited good linearity within the 0.01-1.0 µM concentration range, with a limit of detection (LOD) of 0.005 µM. The proposed electrochemical sensor demonstrated excellent selectivity, accuracy, precision, and repeatability. Furthermore, it effectively detected RXL in human urine and pharmaceutical samples.

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.

Local and Sustained Baricitinib Delivery to the Skin through Injectable Hydrogels Containing Reversible Thioimidate Adducts.

Janus kinase (JAK) inhibitors are approved for many dermatologic disorders, but their use is limited by systemic toxicities including serious cardiovascular events and malignancy. To overcome these limitations, injectable hydrogels are engineered for the local and sustained delivery of baricitinib, a representative JAK inhibitor. Hydrogels are formed via disulfide crosslinking of thiolated hyaluronic acid macromers. Dynamic thioimidate bonds are introduced between the thiolated hyaluronic acid and nitrile-containing baricitinib for drug tethering, which is confirmed with 1H and 13C nuclear magnetic resonance (NMR). Release of baricitinib is tunable over six weeks in vitro and active in inhibiting JAK signaling in a cell line containing a luciferase reporter reflecting interferon signaling. For in vivo activity, baricitinib hydrogels or controls are injected intradermally into an imiquimod-induced mouse model of psoriasis. Imiquimod increases epidermal thickness in mice, which is unaffected when treated with baricitinib or hydrogel alone. Treatment with baricitinib hydrogels suppresses the increased epidermal thickness in mice treated with imiquimod, suggesting that the sustained and local release of baricitinib is important for a therapeutic outcome. This study is the first to utilize a thioimidate chemistry to deliver JAK inhibitors to the skin through injectable hydrogels, which has translational potential for treating inflammatory disorders.

Computer-Aided Drug Design of Novel Derivatives of 2-Amino-7,9-dihydro-8H-purin-8-one as Potent Pan-Janus JAK3 Inhibitors.

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 R2 = 0.93, R = 0.96, and Q2 = 87, and atom-based with R2 = 0.94, R = 0.97, and Q2 = 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 pIC50 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.

Design, Synthesis and Structure-Activity Relationship Studies of Meridianin Derivatives as Novel JAK/STAT3 Signaling Inhibitors.

Hyperactivation of Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling is an attractive therapeutic target for tumor therapy. Herein, forty-eight novel meridianin derivatives were designed and synthesized, and their antitumor activity was evaluated in vitro both for activity optimization and structure-activity relationship (SAR) study. The results indicated that most derivatives exhibited significantly improved antitumor activity, especially for compound 6e. The compound 6e contains an isothiouronium linked by an alkyl chain consisting of six carbon atoms with IC50 ranging from 1.11 to 2.80 µM on various cancer cell lines. Consistently, the 6e dose dependently induced the apoptosis of A549 and DU145 cells, in which STAT3 is constitutively active. Western blotting assays indicated that the phosphorylation levels of JAK1, JAK2 and STAT3 were inhibited by 6e at 5 µM without significant change in the total STAT3 level. Moreover, 6e also suppressed the expression of STAT3 downstream genes, including c-Myc, Cyclin D1 and Bcl-XL at 10 µM. An additional in vivo study revealed that 6e at the dose of 10 mg/kg could potently inhibit the DU145 xenograft tumor without obvious body weight loss. These results clearly indicate that 6e could be a potential antitumor agent by targeting the JAK/STAT3 signaling pathway.

Clinically used JAK inhibitor blunts dsRNA-induced inflammation and calcification in aortic valve interstitial cells.

Calcific aortic valve disease (CAVD) is the most prevalent valvulopathy worldwide. Growing evidence supports a role for viral and cell-derived double-stranded (ds)-RNA in cardiovascular pathophysiology. Poly(I:C), a dsRNA surrogate, has been shown to induce inflammation, type I interferon (IFN) responses, and osteogenesis through Toll-like receptor 3 in aortic valve interstitial cells (VIC). Here, we aimed to determine whether IFN signaling via Janus kinase (JAK)/Signal transducers and activators of transcription (STAT) mediates dsRNA-induced responses in primary human VIC. Western blot, ELISA, qPCR, calcification, flow cytometry, and enzymatic assays were performed to evaluate the mechanisms of dsRNA-induced inflammation and calcification. Poly(I:C) triggered a type I IFN response characterized by IFN-regulatory factors gene upregulation, IFN-ß secretion, and STAT1 activation. Additionally, Poly(I:C) promoted VIC inflammation via NF-κB and subsequent adhesion molecule expression, and cytokine secretion. Pretreatment with ruxolitinib, a clinically used JAK inhibitor, abrogated these responses. Moreover, Poly(I:C) promoted a pro-osteogenic phenotype and increased VIC calcification to a higher extent in cells from males. Inhibition of JAK with ruxolitinib or a type I IFN receptor blocking antibody blunted Poly(I:C)-induced calcification. Mechanistically, Poly(I:C) promoted VIC apoptosis in calcification medium, which was inhibited by ruxolitinib. Moreover, Poly(I:C) co-operated with IFN-γ to increase VIC calcification by synergistically activating extracellular signal-regulated kinases and hypoxia-inducible factor-1α pathways. In conclusion, JAK/STAT signaling mediates dsRNA-triggered inflammation, apoptosis, and calcification and may contribute to a positive autocrine loop in human VIC in the presence of IFN-γ. Blockade of dsRNA responses with JAK inhibitors may be a promising therapeutic avenue for CAVD.

Fedratinib, a newly approved treatment for patients with myeloproliferative neoplasm-associated myelofibrosis.

Myeloproliferative neoplasm (MPN)-associated myelofibrosis (MF) is characterized by cytopenias, marrow fibrosis, constitutional symptoms, extramedullary hematopoiesis, splenomegaly, and shortened survival. Constitutive activation of the janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in MF leads to cell proliferation, inhibition of cell death, and clonal expansion of myeloproliferative malignant cells. Fedratinib is a selective oral JAK2 inhibitor recently approved in the United States for treatment of adult patients with intermediate-2 or high-risk MF. In mouse models of JAK2V617F-driven myeloproliferative disease, fedratinib blocked phosphorylation of STAT5, increased survival, and improved MF-associated disease features, including reduction of white blood cell counts, hematocrit, splenomegaly, and fibrosis. Fedratinib exerts off-target inhibitory activity against bromodomain-containing protein 4 (BRD4); combination JAK/STAT and BRD4 inhibition was shown to synergistically block NF-kB hyperactivation and inflammatory cytokine production, attenuating disease burden and reversing bone marrow fibrosis in animal models of MPNs. In patients, fedratinib is rapidly absorbed and dosed once daily (effective half-life 41 h). Fedratinib showed robust clinical activity in JAK-inhibitor-naïve patients and in patients with MF who were relapsed, refractory, or intolerant to prior ruxolitinib therapy. Fedratinib is effective regardless of JAK2 mutation status. Onset of spleen and symptom responses are typically seen within the first 1-2 months of treatment. The most common adverse events (AEs) with fedratinib are grades 1-2 gastrointestinal events, which are most frequent during early treatment and decrease over time. Treatment discontinuation due to hematologic AEs in clinical trials was uncommon (~3%). Suspected cases of Wernicke's encephalopathy were reported during fedratinib trials in ~1% of patients; thiamine levels should be monitored before and during fedratinib treatment as medically indicated. Phase III trials are ongoing to assess fedratinib effects on long-term safety, efficacy, and overall survival. The recent approval of fedratinib provides a much-needed addition to the limited therapeutic options available for patients with MF.

Pulmonary adverse events of small molecule JAK inhibitors in autoimmune disease: systematic review and meta-analysis.

OBJECTIVES: Small molecule tyrosine kinase inhibitors [smTKI, comprising mostly of Janus kinase (JAK) and to a lesser extent, spleen tyrosine kinase (SyK) inhibitors] modulate the cytokine receptor-mediated intracellular signal cascade, and are an effective treatment for autoimmune diseases and malignancies. As smTKI are novel, long-term safety is uncertain. Due to increasing use, characterization of their true adverse event profile is critical. METHODS: We performed a systematic review and meta-analysis of all published trial data on the pulmonary and serious adverse effects of smTKIs in autoimmune disease. EMBASE, MEDLINE, CENTRAL and Pneumotox databases were searched up to April 2019 for randomized controlled trials, observational studies and post marketing surveillance, comparing any smTKI with placebo or another therapy, or as monotherapy at different doses. Primary outcomes comprised of any respiratory complications including upper and lower respiratory tract infections (URTI, LRTI), influenza, pneumonia, opportunistic respiratory infections, drug-induced interstitial lung disease, pulmonary embolism and lung neoplasm. RESULTS: We identified 4667 citations for screening, and selected 319 studies for full text review. Seventy-nine studies were analysed, including 47 randomized controlled trials, 25 observational studies and seven post-marketing surveillance studies, comprising 159 652 participants. There were significantly increased risks of URTI [risk difference (RD) 0.03; 95% CI: 0.01, 0.05; P = 0.00; 36 studies, 14 724 participants], LRTI (RD 0.01; 95% CI: 0.00, 0.02; P = 0.02; 24 studies, 12 302 participants), influenza (RD 0.01; 95% CI: 0.00, 0.01; P = 0.04; 22 studies, 10 684 participants), and pneumonia (RD 0.00; 95% CI: 0.00, 0.01; P = 0.02; 33 studies, 15 511 participants). No increased risk was found for other respiratory complications, including pulmonary embolism. CONCLUSION: SmTKI increases the risk of non-opportunistic respiratory infections compared with placebo. The risk of any serious pulmonary adverse events is low.

Solubility Data and Computational Modeling of Baricitinib in Various (DMSO + Water) Mixtures.

The solubility and thermodynamic analysis of baricitinib (BNB) in various dimethyl sulfoxide (DMSO) + water mixtures were performed. The "mole fraction solubilities (xe)" of BNB in DMSO and water mixtures were determined at "T = 298.2-323.2 K" and "p = 0.1 MPa" using an isothermal saturation technique. "Hansen solubility parameters (HSPs)" of BNB, pure DMSO, pure water and "DMSO + water" mixtures free of BNB were also estimated. The xe data of BNB was regressed well by five different thermodynamics-based co-solvency models, which included "Apelblat, Van't Hoff, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van't Hoff models" with overall deviations of <5.0%. The highest and lowest xe value of BNB was computed in pure DMSO (1.69 × 10-1 at T = 323.2 K) and pure water (2.23 × 10-5 at T = 298.2 K), respectively. The HSP of BNB was found to be closer to that of pure DMSO. Based on activity coefficient data, maximum solute-solvent molecular interactions were observed in BNB-DMSO compared to BNB-water. The results of "apparent thermodynamic analysis" indicated endothermic and entropy-drive dissolution of BNB in all "DMSO + water" combinations including mono-solvents (water and DMSO). "Enthalpy-entropy compensation analysis" showed enthalpy-driven to be the main mechanism of solvation of BNB.

Delgocitinib: First Approval.

Delgocitinib, a janus kinase (JAK) inhibitor, is being developed by Japan Tobacco for the treatment of autoimmune disorders and hypersensitivity, including inflammatory skin conditions. The JAK family of tyrosine kinases plays an important role in mediating the biological effects of several inflammatory cytokines, e.g. IL-4, IL-13 and IL-31, which are elevated in patients with atopic dermatitis. Delgocitinib inhibits all members of the JAK family [JAK1, JAK2, JAK3 and tyrosine kinase 2]. Topical delgocitinib (Corectim®) is approved in Japan for the treatment of atopic dermatitis. This article summarizes the milestones in the development of delgocitinib leading to this first approval for the treatment of adults with atopic dermatitis. Clinical development of the topical formulation is also underway for alopecia areata, chronic hand eczema, discoid lupus erythematosus, inverse psoriasis and atopic dermatitis in several countries worldwide. Clinical development of an oral formulation of delgocitinib is also underway in Japan for the treatment of autoimmune disorders and hypersensitivity.

An Update on JAK Inhibitors.

Janus kinases (JAKs) are a family of non-receptor tyrosine kinases, composed by four members, JAK1, JAK2, JAK3 and TYK2. JAKs are involved in different inflammatory and autoimmune diseases, as well as in malignancies, through the activation of the JAK/STAT signalling pathway. Furthermore, the V617F mutation in JAK2 was identified in patients affected by myeloproliferative neoplasms. This knowledge prompted researchers from academia and pharmaceutical companies to investigate this field in order to discover small molecule JAK inhibitors. These efforts recently afforded to the market approval of four JAK inhibitors. Despite the fact that all these drugs are pyrrolo[2,3-d]pyrimidine derivatives, many compounds endowed with different heterocyclic scaffolds have been reported in the literature as selective or multi-JAK inhibitors, and a number of them is currently being evaluated in clinical trials. In this review we will report many representative compounds that have been published in articles or patents in the last five years (period 2013-2017). The inhibitors will be classified on the basis of their chemical structure, focusing, when possible, on their structure activity relationships, selectivity and biological activity. For every class of derivatives, compounds disclosed before 2013 that have entered clinical trials will also be briefly reported, to underline the importance of a particular chemical scaffold in the search for new inhibitors.

On the Mechanism of Action of Anti-Inflammatory Activity of Hypericin: An In Silico Study Pointing to the Relevance of Janus Kinases Inhibition.

St. John's Wort (Hypericum perforatum L.) flowers are commonly used in ethnomedical preparations with promising outcomes to treat inflammation both per os and by topical application. However, the underlying molecular mechanisms need to be described toward a rational, evidence-based, and reproducible use. For this purpose, the aptitude of the prominent Hypericum metabolite hypericin was assessed, along with that of its main congeners, to behave as an inhibitor of janus kinase 1, a relevant enzyme in inflammatory response. It was used a molecular modeling approach relying on docking simulations, pharmacophoric modeling, and molecular dynamics to estimate the capability of molecules to interact and persist within the enzyme pocket. Our results highlighted the capability of hypericin, and some of its analogues and metabolites, to behave as ATP-competitive inhibitor providing: (i) a likely mechanistic elucidation of anti-inflammatory activity of H. perforatum extracts containing hypericin and related compounds; and (ii) a rational-based prioritization of H. perforatum components to further characterize their actual effectiveness as anti-inflammatory agents.

Development of a Janus Kinase Inhibitor Prodrug for the Treatment of Rheumatoid Arthritis.

While highly efficacious in treating rheumatoid arthritis (RA), the approved Janus kinase (JAK) inhibitor, Tofacitinib (Tofa, CP-690 550), has dose-dependent toxicities that limit its clinical application. In this study, we have examined whether a prodrug design that targets arthritic joints would enhance Tofa's therapeutic efficacy, which may provide an opportunity for future development of safer Tofa dosing regimens. A prodrug of Tofa (P-Tofa) was synthesized by conjugating the drug to the N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer via an acid cleavable carbamate linker. The therapeutic efficacy of a single dose of P-Tofa was compared to the dose-equivalent daily oral administration of Tofa in an adjuvant-induced arthritis (AA) rat model. Saline treated AA rats and age-matched healthy rats were used as controls. Observational analyses support the superior and sustained efficacy of a single dose P-Tofa treatment compared to the dose-equivalent daily Tofa administration in ameliorating joint inflammation. Micro-CT and histological analyses demonstrated that the P-Tofa treatment provided a structural preservation of the joints better than that of the dose-equivalent Tofa. Optical imaging, immunohistochemistry, and fluorescence-activated cell sorting analyses attribute P-Tofa's superior therapeutic efficacy to its passive targeting to arthritic joints and inflammatory cell-mediated sequestration. In vitro cell culture studies reveal that the P-Tofa treatment produced sustained the inhibition of JAK/STAT6 signaling in IL-4-treated murine bone marrow macrophages, consistent with a gradual subcellular release of Tofa. Collectively, a HPMA-based nanoscale prodrug of P-Tofa has the potential to enhance the therapeutic efficacy and widen the therapeutic window of Tofa therapy in RA.

Interaction of 2,4-Diaminopyrimidine-Containing Drugs Including Fedratinib and Trimethoprim with Thiamine Transporters.

Inhibition of thiamine transporters has been proposed as a putative mechanism for the observation of Wernicke's encephalopathy and subsequent termination of clinical development of fedratinib, a Janus kinase inhibitor (JAKi). This study aimed to determine the potential for other JAKi to inhibit thiamine transport using human epithelial colorectal adenocarcinoma (Caco-2) and thiamine transporter (THTR) overexpressing cells and to better elucidate the structural basis for interacting with THTR. Only JAKi containing a 2,4-diaminopyrimidine were observed to inhibit thiamine transporters. Fedratinib inhibited thiamine uptake into Caco-2 cells (IC50 = 0.940 µM) and THTR-2 (IC50 = 1.36 µM) and, to a lesser extent, THTR-1 (IC50 = 7.10 µM) overexpressing cells. Two other JAKi containing this moiety, AZD1480 and cerdulatinib, were weaker inhibitors of the thiamine transporters. Other JAKi-including monoaminopyrimidines, such as momelotinib, and nonaminopyrimidines, such as filgotinib-did not have any inhibitory effects on thiamine transport. A pharmacophore model derived from the minimized structure of thiamine suggests that 2,4-diaminopyrimidine-containing compounds can adopt a conformation matching several key features of thiamine. Further studies with drugs containing a 2,4-diaminopyrimidine resulted in the discovery that the antibiotic trimethoprim also potently inhibits thiamine uptake mediated by THTR-1 (IC50 = 6.84 µM) and THTR-2 (IC50 = 5.56 µM). Fedratinib and trimethoprim were also found to be substrates for THTR, a finding with important implications for their disposition in the body. In summary, our results show that not all JAKi have the potential to inhibit thiamine transport and further establish the interaction of these transporters with xenobiotics.