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Introduction: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by persistent itching. Conventional treatments for AD include topical corticosteroids and calcineurin inhibitors, but there are emerging therapies targeting the JAK-TYK2 pathway that are promising for the treatment of AD., Areas Covered: This review comprehensively explores the pathogenesis, triggers, clinical manifestations, and conventional treatment options for AD. In addition, we discuss novel therapeutic agents targeting alternative signaling pathways, with a focus on clinical trials evaluating tyrosine kinase 2 (TYK2) inhibitors, including systemic and topical agents. We also provide a detailed assessment of ICP-332 efficacy, safety, and potential adverse effects in moderate-to-severe AD., Expert Opinion: Janus kinase inhibitors that have been recently approved have shown promise for the treatment of AD, especially for patients with severe phenotypes. Preliminary findings from randomized controlled trials suggest that TYK2 inhibitors exhibit rapid efficacy and acceptable safety in the management of AD; however, additional investigations, including long-term trials, are warranted to fully understand their efficacy and safety profile.

Translational medicine provides insight into novel drugs and predicts unwanted effects. In well-characterized pathways (e.g., cytokine-Janus kinase [JAK]-signal transducers and activators of transcription [STAT]), a variety of in vitro assessments were used to estimate selectivity of effects on different potential targets (i.e., JAK1, JAK2, JAK3, and tyrosine kinase 2 [TYK2]). Several approved drugs were characterized as selective for the JAK family. These assessments are challenged by a lack of compounds that only inhibit one JAK family member. Deucravacitinib is a first-in-class, oral, selective, allosteric inhibitor of TYK2, a kinase required for IL-12, IL-23, and Type I interferon signaling. Unlike deucravacitinib, which selectively binds to the TYK2 regulatory domain, JAK1,2,3 inhibitors target the catalytic domain, contributing to nonselective targeting of JAK1,2,3. Cytokines associated with JAK1,2,3 signaling are required for both immune and nonimmune functions. A similar laboratory abnormality profile was observed in clinical trials using JAK1,2,3 inhibitors that has not been observed with deucravacitinib. In vitro testing of JAK1,2,3 inhibitors has relied upon assays of signal transduction, such as those measuring STAT phosphorylation, for estimates of potency and selectivity. These assay systems can be effective in estimating in vivo efficacy; however, they may not provide insight into downstream outcomes of receptor signaling, which may be more relevant for evaluating safety aspects. Assay systems assessing functional outcomes from cells may yield a more useful translational evaluation. Here, deucravacitinib was assessed for potency and selectivity versus three representatives of the JAK inhibitor class (tofacitinib, baricitinib, and upadacitinib) based on functional assays. JAK inhibitors had suppressive activity against JAK2-dependent hematopoietic colony-forming assays modeling thrombopoiesis, erythropoiesis, and myelopoiesis; however, deucravacitinib did not. Deucravacitinib had limited potency against NK cells, cytotoxic T cells, T-helper cells, and regulatory T cells activated by JAK1/JAK3-dependent common gamma chain cytokines. These data are consistent with the biologic role of JAK1,2,3 and pharmacodynamic changes in clinical laboratory abnormalities. Against TYK2-dependent cytokines, deucravacitinib selectively inhibited Type I interferon stimulation of monocytes and dendritic cells and was a more potent inhibitor than JAK inhibitors. IL-12 and IL-23 functional outputs were similarly potently inhibited by deucravacitinib. Results are consistent with deucravacitinib selectively inhibiting TYK2., Competing Interests: BJ, LC, JK, and PS are employees of and shareholders in Bristol Myers Squibb. Author IMC was an employee of Bristol Myers Squibb at the time of study conduct., (Copyright © 2024 Johnson, Cheng, Koenitzer, Catlett and Schafer.)

Background Janus kinase (JAK)/tyrosine kinase 2 (TYK2) inhibitors are novel treatments for moderate-to-severe plaque psoriasis. Objective To perform a network meta-analysis to compare the efficacy and safety of TYK2 inhibitors with other oral drugs in moderate-to-severe psoriasis. Methods Eligible randomised clinical trials (RCTs) were identified from public databases (published before November 2, 2023). Random-effect frequentist network meta-analysis was performed with ranking based on the surface under the cumulative ranking curve (SUCRA) of Physician's Global Assessment of "clear" or "almost clear" (PGA 0/1), 75% reduction from baseline in Psoriasis Area and Severity Index (PASI-75). Results Twenty RCTs containing 7,564 patients with moderate-to-severe psoriasis were included. Deucravacitinib at all dose levels (except for 3 mg every other day) and tofacitinib (10 mg BID) ranked best in achieving PGA 0/1 and PASI-75 at 12- 16 weeks. Tofacitinib (10 mg BID) was considered the most unsafe. Analysis of Ranking according to efficacy and safety showed deucravacitinib (3 mg QD and 3 mg BID) was the best treatment. Analysis of Ranking according to efficacy and safety showed deucravacitinib (3 mg QD and 3 mg BID) was the best treatment. Limitation Insufficiency of eligible data and no long-term follow-up data. Conclusion Deucravacitinib showed superior efficacy and safety for treating moderate-to-severe psoriasis over other included drugs.

Members of the Janus kinase (JAK) superfamily, comprising tyrosine kinase 2 (TYK2) and JAK1, JAK2, and JAK3, mediate signaling by cytokines (eg, interleukin [IL]-23) involved in psoriasis pathogenesis. Binding of IL-23 to its receptor activates TYK2 and JAK2, which trigger signal transducer and activator of transcription (STAT) translocation to the nucleus to regulate target gene transcription, including genes of proinflammatory mediators such as IL-17. Physiologically, TYK2 solely mediates immune function, whereas JAK1,2,3 mediate broad systemic and immune functions. Inhibition of individual JAK family members is being evaluated in many dermatologic indications, including psoriasis. Selective TYK2 inhibition is therefore expected to be associated with few adverse effects in patients with psoriasis. People with genetic mutations leading to loss of function of TYK2 are protected from the development of psoriasis without an increased risk of infections or malignancies. In contrast, treatments with JAK1,2,3 inhibitors are associated with various systemic effects. We review the unique allosteric mechanism of action of the selective TYK2 inhibitor, deucravacitinib, which binds to the TYK2 regulatory (pseudokinase) domain, and the mechanisms of action of JAK1,2,3 inhibitors, which bind to the adenosine 5'-triphosphate-binding active (catalytic) site in the kinase domains of JAK1,2,3. Deucravacitinib, which is approved for the treatment of moderate to severe plaque psoriasis in adults in the United States and several other countries, represents a novel, targeted systemic treatment approach with a favorable safety profile. J Drugs Dermatol. 2024;23(8):645-652.  doi:10.36849/JDD.8293.

Significant research advances in our understanding of psoriatic disease have led to the development of several highly selective, effective, and safe topical and systemic treatments. These treatments have led to unprecedented levels of disease clearance and control for most patients with psoriasis with cutaneous disease. However, there remains a need for improved treatments for those patients with recalcitrant disease, psoriatic arthritis, or nonplaque disease variants. Recently approved therapies and investigational products in ongoing clinical development programs that target IL-17A/F, IL-23, TYK2, PDE4, AhR or IL-36 cytokine signaling are improving the clinician's ability to care for a broader range of patients affected by psoriasis., Competing Interests: Disclosure J.E. Hawkes is a consultant/advisor or speaker for AbbVie, Arcutis, Bristol Myers Squibb, Boehringer Ingelheim, Eli Lilly, Janssen Pharmaceuticals, LEO Pharma, Novartis, Pfizer, Regeneron Pharmaceuticals, Sanofi, Sun Pharmaceutical, and UCB. E.J. Song is a consultant, speaker and/or investigator for AbbVie, Alyphn, Amgen, Apogee, Arcutis, ASLAN, Boehringer Ingelheim, Bristol Myers Squibb, Dermavant, Eli Lilly, Janssen Pharmaceuticals, LEO, Novartis, Ortho-dermatologics, Pfizer, Regeneron Pharmaceuticals, Sanofi, Sun Pharmaceutical, and UCB., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediates many cytokine and growth factor signals. Tyrosine kinase 2 (TYK2), one of the members of this pathway and the first described member of the JAK family. TYK2 associates with inflammatory and autoimmune diseases, cancer and diabetes. Here, we present novel compounds as selective inhibitors of the canonical kinase domain of TYK2 enzyme. These compounds were rationally designed and synthesized with appropriate reactions. Molecular modeling techniques were used to design and optimize the candidates for TYK2 inhibition and to determine the estimated binding orientations of them inside JAKs. Designed compounds potently inhibited TYK2 with good selectivity against other JAKs as determined by in vitro assays. In order to verify its selectivity properties, compound A8 was tested against 58 human kinases (KinaseProfiler™ assay). The effects of the selected seven compounds on the protein levels of members of the JAK/STAT family were also detected in THP-1 monocytes although the basal level of these proteins is poorly detectable. Therefore, their expression was induced by lipopolysaccharide treatment and compounds A8, A15, A18, and A19 were found to be potent inhibitors of the TYK2 enzyme, (9.7 nM, 6.0 nM, 5.0 nM and 10.3 nM, respectively), and have high selectivity index for the JAK1, JAK2, and JAK3 enzymes. These findings suggest that triazolo[1,5-a]pyrimidinone derivatives may be lead compounds for developing potent TYK2-selective inhibitors targeting enzymes' active site., 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.)

Objectives: The tuning effects of JAK/TYK2 inhibitors on the imbalance between T follicular helper (Tfh) and T regulatory (Treg) cells, related to systemic lupus erythematosus (SLE) pathogenesis, were investigated using human peripheral blood samples., Methods: Peripheral blood mononuclear cells from untreated patients with SLE and healthy controls were analysed. Tfh1 cells were identified in nephritis tissue, and the effect of Tfh1 cells on B-cell differentiation was examined by coculturing naïve B cells with Tfh1 cells., Results: Tfh1 cell numbers were increased in the peripheral blood of patients, and activated Treg cell counts were decreased relative to Tfh1 cell counts. This imbalance in the Tfh to Treg ratio was remarkably pronounced in cases of lupus nephritis, especially in types III and IV active nephritis. Immunohistochemistry revealed Tfh1 cell infiltration in lupus nephritis tissues. Co-culture of Tfh1 cells (isolated from healthy individuals) with naïve B cells elicited greater induction of T-bet + B cells than controls. In JAK/TYK2-dependent STAT phosphorylation assays using memory CD4 + T cells, IL-12-induced STAT1/4 phosphorylation and Tfh1 cell differentiation were inhibited by both JAK and TYK2 inhibitors. However, phosphorylation of STAT5 by IL-2 and induction of Treg cell differentiation by IL-2+TGFβ were inhibited by JAK inhibitors but not by TYK2 inhibitors, suggesting that TYK2 does not mediate the IL-2 signalling pathway., Conclusions: Tfh1 cells can induce T-bet + B cell production and may contribute to SLE pathogenesis-associated processes. TYK2 inhibitor may fine-tune the immune imbalance by suppressing Tfh1 differentiation and maintaining Treg cell differentiation, thereby preserving IL-2 signalling, unlike other JAK inhibitors., Competing Interests: Competing interests: YT has received speaking fees and/or honoraria from Eli Lilly, AstraZeneca, Abbvie, Gilead, Chugai, Behringer-Ingelheim, GlaxoSmithKline, Eisai, Taisho, Bristol–Myers, Pfizer, Taiho, received research grants from Mitsubishi-Tanabe, Eisai, Chugai, Taisho. SN has received consulting fees, lecture fees, and/or honoraria from Bristol–Myers, AstraZeneca, Pfizer, GlaxoSmithKline, AbbVie, Astellas, Asahi-Kasei, Sanofi, Chugai, Eisai, Gilead Sciences, Eli Lilly, Boehringer Ingelheim. SK has received consulting fees, speaking fees, and/or honoraria from GlaxoSmithKline, Eli Lilly, and Bristol–Myers and has received research grants from Daiichi-Sankyo, Abbvie, Boehringer Ingelheim and Astellas. All other authors declare no conflict of interest. None of the material presented in our manuscript has been previously submitted or published., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Tyrosine kinase 2 (TYK2) mediates cytokine signaling through type 1 interferon, interleukin (IL)-12/IL-23, and the IL-10 family. There appears to be an association between TYK2 genetic variants and inflammatory conditions, and clinical evidence suggests that selective inhibition of TYK2 could produce a unique therapeutic profile. Here, we describe the discovery of compound 9 (GLPG3667), a reversible and selective TYK2 adenosine triphosphate competitive inhibitor in development for the treatment of inflammatory and autoimmune diseases. The preclinical pharmacokinetic profile was favorable, and TYK2 selectivity was confirmed in peripheral blood mononuclear cells and whole blood assays. Dermal ear inflammation was reduced in an IL-23-induced in vivo mouse model of psoriasis. GLPG3667 also completed a phase 1b study (NCT04594928) in patients with moderate-to-severe psoriasis where clinical effect was shown within the 4 weeks of treatment and it is now in phase 2 trials for the treatment of dermatomyositis (NCT05695950) and systemic lupus erythematosus (NCT05856448).

Brepocitinib is an oral selective dual TYK2/JAK1 inhibitor and based on its cytokine inhibition profile is expected to provide therapeutic benefit in the treatment of plaque psoriasis. Efficacy data from a completed Phase 2a study in patients with moderate-to-severe plaque psoriasis were utilized to develop a population exposure-response model that can be employed to inform dose selection decisions for further clinical development. A modeling approach that employs the zero-inflated beta distribution was used to account for the bounded nature and distributional characteristics of the Psoriasis Area and Severity Index (PASI) score data. The developed exposure-response model provided an adequate description of the observed PASI scores across all the treatment arms tested and across both the induction and maintenance dosing periods of the study. In addition, the developed model exhibited a good predictive capacity with regard to the derived responder metrics (e.g., 75%/90%/100% improvement in PASI score [PASI75/90/100]). Clinical trial simulations indicated that the induction/maintenance dosing paradigm explored in this study does not offer any advantages from an efficacy perspective and that doses of 10, 30, and 60 mg once-daily may be suitable candidates for clinical evaluation in subsequent Phase 2b studies., (© 2024. The Author(s).)

Tyrosine kinase 2 (TYK2) is a member of the JAK kinase family of intracellular signalling molecules. By participating in signalling pathways downstream of type I interferons, IL-12, IL-23 and IL-10, TYK2 elicits a distinct set of immune events to JAK1, JAK2 and JAK3. TYK2 polymorphisms have been associated with susceptibility to various rheumatic diseases including systemic lupus erythematosus and dermatomyositis. In vitro and animal studies substantiate these findings, highlighting a role for TYK2 in diseases currently managed by antagonists of cytokines that signal through TYK2. Various inhibitors of TYK2 have now been studied in human disease, and one of these inhibitors, deucravacitinib, has now been approved for the treatment of psoriasis. Phase II trials of deucravacitinib have also reported positive results in the treatment of psoriatic arthritis and systemic lupus erythematosus, with a preliminary safety profile that seems to differ from that of the JAK1, JAK2 and JAK3 inhibitors. Two other inhibitors of TYK2, brepocitinib and ropsacitinib, are also in earlier stages of clinical trials. Overall, TYK2 inhibitors hold promise for the treatment of a distinct spectrum of autoimmune diseases and could potentially have a safety profile that differs from other JAK inhibitors., (© 2024. Springer Nature Limited.)

Erosive oral lichen planus (OLP) is a challenging disease. This T cell driven disorder frequently shows a treatment unresponsive course and strongly limits patients' quality of life. The disease lacks FDA or EMA approved drugs for its treatment and the efficacy of the commonly administered treatments (i.e. topical and systemic steroids, steroid sparing agents) is often only partial. Although the etiopathogenesis of the disease still needs to be fully elucidated, recent advances helped to identify interferon-ɣ (IFN-ɣ) as a pivotal cytokine in OLP pathogenesis, thus making the interference with its signalling a therapeutic target. Janus kinase (JAK) inhibitors therefore gained relevance for their inhibitory effect on IFN-ɣ signalling. While some drugs such as abrocitinib, upadacitinib, tofacitinib directly interfere with IFN-ɣ signalling through blockade of JAK1 and/or JAK2, deucravacitinib, a selective TYK-2 inhibitor indirectly interferes on IFN-ɣ activation through interference with interleukin (IL)-12, a potent promotor for Th1/IFN-ɣ responses. This mechanism of action makes deucravacitinib a candidate drug for the treatment of OLP. Here we provide initial evidence that deucravacitinib 6 mg daily has a beneficial effect in three patients with oral OLP., (© 2024 The Authors. Experimental Dermatology published by John Wiley & Sons Ltd.)

Background: Scalp involvement in plaque psoriasis is challenging to treat., Objective: To evaluate the efficacy and safety of deucravacitinib (DEUC) in scalp psoriasis., Methods: POETYK PSO-1 and PSO-2 were global phase 3, 52-week, double-blinded trials in adults with moderate to severe psoriasis. Patients were randomized 1:2:1 to oral placebo, DEUC 6 mg once daily, or apremilast 30 mg twice daily. This pooled secondary analysis evaluated scalp-specific Physician Global Assessment score of 0 or 1 (0/1), ≥90% improvement from baseline in Psoriasis Scalp Severity Index, and change from baseline in Psoriasis Scalp Severity Index. Adverse events were evaluated through week 16., Results: Overall, 1084 patients with moderate to severe scalp psoriasis at baseline were included. At week 16, response rates were greater with DEUC versus placebo or apremilast for scalp-specific Physician Global Assessment 0/1 (64.0% vs 17.3% vs 37.7%; P < .0001), ≥90% improvement from baseline in Psoriasis Scalp Severity Index (50.6% vs 10.5% vs 26.1%; P < .0001), and change from baseline in Psoriasis Scalp Severity Index. Responses were maintained through 52 weeks with continuous DEUC. Safety was consistent with the entire study population., Limitations: Lack of data in milder scalp psoriasis., Conclusion: DEUC was significantly more efficacious than placebo or apremilast in improving moderate to severe scalp psoriasis and was well tolerated., Competing Interests: Conflicts of interest Dr Blauvelt has served as a speaker/received honoraria from AbbVie, Eli Lilly and Company, and UCB, served as a scientific adviser/received honoraria from AbbVie, Abcentra, Affibody, Aligos, Almirall, Alumis, Amgen, AnaptysBio, Arcutis, Arena, Aslan, Athenex, Bluefin Biomedicine, Boehringer Ingelheim, Bristol Myers Squibb, Cara Therapeutics, Dermavant, EcoR1, Eli Lilly, Escient, Evelo Biosciences, Evommune, Forte Biosciences, Galderma, HighlightII Pharma, Incyte, Janssen, Landos, Leo Pharma, Merck, Novartis, Pfizer, Rapt, Regeneron, Sanofi Genzyme, Spherix Global Insights, Sun Pharma, TLL Pharmaceutical, TrialSpark, UCB, Vibliome, and Xencor, and has acted as a clinical study investigator/institution has received clinical study funds from AbbVie, Acelyrin, Amgen, Arcutis, Athenex, Boehringer Ingelheim, Bristol Myers Squibb, Concert, Dermavant, Eli Lilly, Evelo Biosciences, Galderma, Incyte, Janssen, Leo Pharma, Merck, Novartis, Pfizer, Regeneron, Sun Pharma, and UCB. Dr Rich has conducted research as a principal investigator for AbbVie, Arcutis, Bristol Myers Squibb, Dermavant, Eli Lilly, Janssen, Novartis, Sun Pharma, and UCB. Dr Sofen has served as a clinical investigator for AbbVie, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Eli Lilly, Janssen, Leo Pharma, Novartis, and Sun Pharma. Dr Strober has served as a consultant (with honoraria) for AbbVie, Alumis, Almirall, Amgen, Arcutis, Arena, Aristea, Asana, Boehringer Ingelheim, Immunic Therapeutics, Bristol Myers Squibb, Connect Biopharma, Dermavant, Eli Lilly, EPI Health, Evelo Biosciences, Janssen, Leo Pharma, Maruho, Meiji Seika Pharma, Mindera Health, Novartis, Ono Pharmaceutical, Pfizer, Regeneron, Sanofi Genzyme, Sun Pharma, UCB, UNION Therapeutics, Ventyx Biosciences, and vTv Therapeutics; has stock options in Connect Biopharma and Mindera Health; has served as a speaker for AbbVie, Eli Lilly, Incyte, Janssen, Regeneron, and Sanofi Genzyme; served a scientific co-director (with a consulting fee) for CorEvitas Psoriasis Registry; and has served as an investigator for AbbVie, Cara Therapeutics, CorEvitas Psoriasis Registry, Dermavant, Dermira, and Novartis. Dr Merola has served as a consultant and/or investigator for Amgen, AbbVie, Biogen, Bristol Myers Squibb, Dermavant, Eli Lilly, Janssen, Leo Pharma, Novartis, Pfizer, Regeneron, Sanofi, Sun Pharma, and UCB. Dr Lebwohl has received research funds on behalf of Mount Sinai from AbbVie, Amgen, Arcutis, Avotres, Boehringer Ingelheim, Dermavant, Eli Lilly, Incyte, Janssen, Ortho Dermatologics, Regeneron, and UCB, and has served as a consultant for Aditum Bio, Almirall, AltruBio, AnaptysBio, Arcutis, Arena, Aristea, Arrive Technologies, Avotres, BiomX, Boehringer Ingelheim, Brickell Biotech, Bristol Myers Squibb, Cara Therapeutics, Castle Biosciences, CorEvitas Psoriasis Registry, Dermavant, Dr Reddy's Laboratories, Evelo Biosciences, Evommune, Forte Biosciences, Helsinn Therapeutics, Hexima, Leo Pharma, Meiji Seika Pharma, Mindera Health, Pfizer, Seanergy, and Verrica. Dr Morita has received honoraria as meeting chair/lecturer from AbbVie, AYUMI Pharmaceutical, Boehringer Ingelheim Japan, Celgene K.K., Eisai, Eli Lilly Japan K.K., Inforward, Janssen Pharmaceutical K.K., Kyowa Kirin, Maruho, Mitsubishi Tanabe Pharma, Nippon Kayaku, Novartis Pharma K.K., Taiho Pharmaceutical, Torii Pharmaceutical, and Ushio; has received funding from AbbVie GK, Eisai, Eli Lilly Japan K.K., Kyowa Hakko Kirin, Leo Pharma KK, Maruho, Mitsubishi Tanabe Pharma, Novartis Pharma K.K., Taiho Pharmaceutical, and Torii Pharmaceutical; and has received consulting fees from AbbVie GK, Boehringer Ingelheim Japan, Bristol Myers Squibb, Celgene K.K., Eli Lilly Japan K.K., GlaxoSmithKline K.K., Janssen Pharmaceutical K.K., Kyowa Kirin, Maruho, Mitsubishi Tanabe Pharma, Nichi-Iko Pharmaceutical, Nippon Kayaku, Novartis Pharma K.K., NPO Health Institute Research of Skin, Pfizer Japan, Sun Pharma, Torii Pharmaceutical, and UCB Japan. Dr Szepietowski has served as an advisory board member/consultant for AbbVie, Leo Pharma, Novartis, Pierre-Fabre, Sanofi Genzyme, and Trevi; has served as a speaker for AbbVie, Eli Lilly, Janssen-Cilag, Leo Pharma, Novartis, and Sanofi Genzyme; and has served as an investigator for AbbVie, Amgen, Bristol Myers Squibb, Galapagos, Galderma, Incyte, InfraRx, Janssen-Cilag, Menlo Therapeutics, Merck, Novartis, Pfizer, Regeneron, Trevi, and UCB. Dr Lambert has received unrestricted grants from AbbVie, Almirall, Celgene, Eli Lilly, Janssen-Cilag, Leo Pharma, Novartis, and UCB; has served as a speaker for AbbVie, Almirall, Bristol Myers Squibb, Janssen-Cilag, Pfizer, and UCB; and has served as a consultant for AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen-Cilag, Leo Pharma, Novartis, and UCB. Ms. Hippeli, Dr Colston, Dr Balagula, and Dr Banerjee are employees of and stockholders in Bristol Myers Squibb. Dr Thaçi has received grant/research support from, served as a consultant for, and served on a scientific advisory board speakers bureau for AbbVie, Almirall, Amgen, Biogen Idec, Boehringer Ingelheim, Bristol Myers Squibb, Celltrion, Eli Lilly, Galderma, Janssen-Cilag, Leo Pharma, New Bridge, Novartis, Pfizer, Regeneron, Roche, Sandoz-Hexal, Sanofi, Target-Solution, and UCB., (Copyright © 2023 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

TYK2 (tyrosine-protein kinase 2) is a non-receptor protein kinase belonging to the JAK family and is closely associated with various diseases, such as psoriasis, inflammatory bowel disease, systemic lupus erythematosus. TYK2 activates the downstream proteins STAT1-5 by participating in the signal transduction of immune factors such as IL-12, IL-23, and IL-10, resulting in immune expression. The activity of the inhibitor TYK2 can effectively block the transduction of excessive immune signals and treat diseases. TYK2 inhibitors are divided into two types of inhibitors according to the different binding sites. One is a TYK2 inhibitor that binds to JH2 and inhibits its activity through an allosteric mechanism. The representative inhibitor is BMS-986165, developed by Bristol-Myers Squibb. The other class binds to the JH1 adenosine triphosphate (ATP) site and prevents the catalytic activity of the kinase by blocking ATP and downstream phosphorylation. This paper mainly introduces the protein structure, signaling pathway, synthesis, structure-activity relationship and clinical research of TYK2 inhibitors., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Orally administered small-molecule drugs including tyrosine kinase 2 (TYK2) inhibitors and phosphodiesterase 4 (PDE4) inhibitors are new candidates for systemic therapy in plaque psoriasis. However, no previous articles evaluated the benefit and risk profile of TYK2 and PDE4 inhibitors in psoriasis., Objectives: The objective of this study was to compare the efficacy and safety of oral small-molecule drugs, including TYK2 and PDE4 inhibitors, in treating moderate-to-severe plaque psoriasis., Methods: PubMed, Embase, and Cochrane library were searched for eligible randomized clinical trials (RCTs). Response rates for a 75% reduction from baseline in Psoriasis Area and Severity Index (PASI-75) and Physician's Global Assessment score of 0 or 1 (PGA 0/1) were used for efficacy assessment. Safety was evaluated with the incidence of adverse events (AEs). A Bayesian multiple treatment network meta-analysis (NMA) was performed., Results: In total, 13 RCTs (five for TYK2 inhibitors and eight for PDE4 inhibitors) involving 5274 patients were included. The study found that deucravacitinib at any dose (except for 3 mg QOD), ropsacitinib (200 and 400 mg QD), and apremilast (20 and 30 mg BID) had higher PASI and PGA response rates than placebo. In addition, deucravacitinib (3 mg BID, 6 mg QD, 6 mg BID, and 12 mg QD), and ropsacitinib (400 mg QD) showed superior efficacy than apremilast (30 mg BID). In terms of safety, deucravacitinib or ropsacitinib at any dose did not lead to a higher incidence of AEs than apremilast (30 mg BID). The ranking analysis of efficacy revealed that deucravacitinib 12 mg QD and deucravacitinib 3 mg BID had the highest chance of being the most effective oral treatment, followed by deucravacitinib 6 mg BID and ropsacitinib 400 mg QD., Conclusions: Oral TYK2 inhibitors demonstrated satisfactory performance in treating psoriasis, surpassing apremilast at certain doses. More large-scale, long-term studies focusing on novel TYK2 inhibitors are needed., Systematic Review Registration: PROSPERO (ID: CRD42022384859), available from: https://www.crd.york.ac.uk/prospero/display&#95;record.php?ID=CRD42022384859, identifier CRD42022384859., Competing Interests: The 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 © 2023 Xu, Li, Wu, Guo and Jiang.)

Deucravacitinib is an oral, selective, allosteric tyrosine kinase 2 (TYK2) inhibitor that demonstrated superior efficacy versus placebo and apremilast in a global phase 3 trial (POETYK PSO-1; NCT03624127) in patients with moderate to severe plaque psoriasis (N = 666). This report describes efficacy and safety in Japanese patients from this study (N = 66) who were randomly assigned to treatment with deucravacitinib 6 mg once daily (n = 32), placebo (n = 17), or apremilast 30 mg twice daily (n = 17). Patients randomized to placebo crossed over to deucravacitinib at Week 16. Patients randomized to apremilast who did not achieve ≥50% reduction from baseline in Psoriasis Area and Severity Index (PASI 50) score at Week 24 switched to deucravacitinib. The proportion of Japanese patients achieving ≥75% reduction from baseline in PASI (PASI 75) score was numerically higher with deucravacitinib versus placebo and apremilast at Week 16 (78.1% vs. 11.8% and 23.5%, respectively) and versus apremilast at Week 24 (78.1% vs. 29.4%). A numerically higher proportion of patients achieved a static Physician's Global Assessment score of 0 or 1 (clear or almost clear) with at least a two-point improvement from baseline (sPGA 0/1) with deucravacitinib versus placebo or apremilast at Week 16 (75.0% vs. 11.8% and 35.3%) and versus apremilast at Week 24 (75.0% vs. 29.4%). Findings for other clinical and patient-reported outcomes also favored deucravacitinib. Response rates were maintained through 52 weeks in the deucravacitinib group. Incidence rates for adverse events per 100 person-years (PY) in the Japanese patients were comparable across treatment groups through Week 52 (deucravacitinib, 336.8/100 PY; placebo, 321.0/100 PY; apremilast, 358.6/100 PY). The most frequently reported adverse event with deucravacitinib was nasopharyngitis. The efficacy and safety of deucravacitinib in Japanese patients was consistent with those in the global population in POETYK PSO-1., (© 2023 The Authors. The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.)

This is the English version of Japanese guidance for the use of oral Janus kinase (JAK) inhibitors (JAK1 and tyrosine kinase 2 [TYK2] inhibitors) in the treatments of psoriasis. Several cytokines, such as interleukin (IL)-6, IL-7, IL-12, IL-21, IL-22, IL-23, interferon (IFN)-α, and IFN-γ, are involved in the pathogenesis of psoriasis (including psoriatic arthritis). As oral JAK inhibitors hinder the JAK-signal transducers and activators of transcription signal transduction routes involved in the signal transduction of these cytokines, they may be effective for the treatment of psoriasis. JAK has four types: JAK1, JAK2, JAK3, and TYK2. Regarding the use of oral JAK inhibitors for the treatment of psoriasis in Japan, indications of the JAK1 inhibitor upadacitinib were extended also to psoriatic arthritis in 2021, and the use of the TYK2 inhibitor deucravacitinib for plaque-type psoriasis, pustular psoriasis, and erythrodermic psoriasis became covered by health insurance in 2022. This guidance was developed for board-certified dermatologists who specialize in the treatment of psoriasis and to promote the proper use of oral JAK inhibitors. In the package inserts and guides for appropriate use, upadacitinib and deucravacitinib are classified as a "JAK inhibitor" and a "TYK2 inhibitor", respectively, and it is possible that there may be differences in safety between the two drugs. The safety of these drugs will be evaluated for the future by the postmarketing surveillance for molecularly targeted drugs for psoriasis of the Japanese Dermatological Association., (© 2023 Japanese Dermatological Association.)

Background: Deucravacitinib, an oral, selective, allosteric tyrosine kinase 2 inhibitor, inhibits cytokine signaling in psoriasis pathogenesis., Objective: The objective of this study was to demonstrate deucravacitinib superiority versus placebo and apremilast in moderate to severe plaque psoriasis based on ≥75% reduction from baseline in Psoriasis Area and Severity Index and a static Physician's Global Assessment score of 0 (clear) or 1 (almost clear) with a ≥2-point improvement from baseline at week 16., Methods: POETYK psoriasis second trial (NCT03611751), a 52-week, double-blinded, phase 3 trial, randomized patients 2:1:1 to deucravacitinib 6 mg every day (n = 511), placebo (n = 255), or apremilast 30 mg twice a day (n = 254)., Results: At week 16, significantly more deucravacitinib-treated patients versus placebo and apremilast patients achieved ≥75% reduction from baseline in Psoriasis Area and Severity Index (53.0% vs 9.4% and 39.8%; P < .0001 vs placebo; P = .0004 vs apremilast) and static Physician's Global Assessment score of 0 or 1 (49.5% vs 8.6% and 33.9%; P < .0001 for both). Efficacy was maintained until week 52 with continuous deucravacitinib. The most frequent adverse event with deucravacitinib was nasopharyngitis. Serious adverse events and discontinuations due to adverse events were infrequent. No clinically meaningful changes were observed in laboratory parameters., Limitations: The study duration was 1 year., Conclusion: Deucravacitinib demonstrated superiority versus placebo and apremilast and was well tolerated in adults with moderate to severe plaque psoriasis., Competing Interests: Conflicts of interest Dr Strober has served as a consultant (honoraria) for AbbVie, Almirall, Amgen, Arcutis, Arena, Aristea, Asana, Boehringer Ingelheim, Bristol Myers Squibb, Connect Biopharma, Dermavant, Eli Lilly, Equillium, GlaxoSmithKline, Immunic Therapeutics, Janssen, Leo Pharma, Maruho, Meiji Seika Pharma, Mindera, Novartis, Ortho Dermatologics, Pfizer, Regeneron, Sanofi Genzyme, Sun Pharma, UCB, Ventyxbio, and vTv Therapeutics; has served as a speaker for AbbVie, Eli Lilly, Janssen, and Sanofi Genzyme; has served as a coscientific director (consulting fee) for CorEvitas' (Corrona) Psoriasis Registry; and has served as an investigator for AbbVie, Cara, CorEvitas' (Corrona) Psoriasis Registry, Dermavant, Dermira, and Novartis. Dr Thaçi has received grant/research support from and served on a scientific advisory board and a speakers bureau for AbbVie, Almirall, Amgen, Biogen Idec, Boehringer Ingelheim, Eli Lilly, Galapagos, Galderma, Janssen-Cilag, Leo Pharma, Novartis, Pfizer, Regeneron, Roche, Sandoz-Hexal, Sanofi, Target-Solution, and UCB. Dr Sofen has served as a clinical investigator for AbbVie, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Eli Lilly, Janssen, Leo Pharma, Novartis, and Sun Pharma. Dr Kircik has received research grants from AbbVie, Allergan, Almirall, Amgen, Arcutis, Boehringer Ingelheim, Breckinridge Pharma, Bristol Myers Squibb, Celgene, Cellceutix, Centocor, Combinatrix, Connetics, Coria, Dermavant, Dermira, Dow Pharma, Dr Reddy's Laboratories, Eli Lilly, Galderma, Genentech, GlaxoSmithKline, Idera, Johnson & Johnson, Leo Pharma, Maruho, Merck, Medicis, Novartis AG, Pfizer, PharmaDerm, Promius, Stiefel, Sun Pharma, UCB, Valeant, and XenoPort; has received honoraria from AbbVie, Allergan, Almirall, Amgen, Arcutis, Biogen Idec, Bristol Myers Squibb, Celgene, Cipher, Connetics, Dermavant, Dermira, Dr Reddy's Laboratories, Eli Lilly, Galderma, Genentech, GlaxoSmithKline, Johnson & Johnson, Leo Pharma, Merck, Novartis AG, PharmaDerm, Promius, Serono (Merck Serono International SA), Stiefel, Sun Pharma, Taro, UCB, and Valeant. Dr Gordon has received grant support and consulting fees from AbbVie, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Novartis, and UCB, and has received consulting fees from Amgen, Almirall, Dermira, Leo Pharma, Pfizer, and Sun Pharma. Dr Foley has received grant support from Amgen, Bristol Myers Squibb, Celgene, Eli Lilly, Galderma, Janssen, Leo Pharma, Merck, Novartis, Pfizer, Sanofi, and Sun Pharma; has served as an investigator for AbbVie, Amgen, Arcutis, Argenx, Aslan, AstraZeneca, Boehringer Ingelheim, Botanix, Bristol Myers Squibb, Celgene, Celtaxsys, CSL, Cutanea, Dermira, Eli Lilly, Evelo, Galderma, Genentech, Geneseq, GlaxoSmithKline, Hexima, Janssen, Kymab, Leo Pharma, Merck, Novartis, Pfizer, Regeneron, Reistone, Roche, Sanofi, Sun Pharma, Teva, UCB, and Valeant; has served on advisory boards for AbbVie, Amgen, Aslan, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Eli Lilly, Galderma, GlaxoSmithKline, Janssen, Leo Pharma, Mayne Pharma, MedImmune, Novartis, Pfizer, Sanofi, Sun Pharma, UCB, and Valeant; has served as a consultant for Aslan, Bristol Myers Squibb, Eli Lilly, Galderma, GenesisCare, Hexima, Janssen, Leo Pharma, Mayne Pharma, Novartis, Pfizer, Roche, and UCB; has received travel grants from AbbVie, Eli Lilly, Galderma, Janssen, Leo Pharma, Merck, Novartis, Pfizer, Roche, Sanofi, and Sun Pharma; and has served as a speaker for or received honoraria from AbbVie, Amgen, Celgene, Eli Lilly, Galderma, GlaxoSmithKline, Janssen, Leo Pharma, Merck, Novartis, Pfizer, Roche, Sanofi, Sun Pharma, and Valeant. Dr Rich has received research grants as a principal investigator on pharmaceutical trials from AbbVie, Arcutis, Bristol Myers Squibb, Dermavant, Eli Lilly, Janssen, Novartis, Sun Pharma, and UCB. Dr Paul has received grants from and has been a consultant for AbbVie, Almirall, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Leo Pharma, Merck, Mylan, Novartis, Pfizer, Sandoz, and UCB. Dr Bagel has received research funds payable to the Psoriasis Treatment Center of New Jersey from AbbVie, Amgen, Arcutis, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, CorEvitas' (Corrona) Psoriasis Registry, Dermavant, Dermira/UCB, Eli Lilly, Glenmark, Janssen Biotech, Kadmon, Leo Pharma, Lycera, Menlo Therapeutics, Novartis, Pfizer, Regeneron, Sun Pharma, Taro, and Valeant; has served as a consultant for AbbVie, Amgen, Celgene, Eli Lilly, Janssen Biotech, Novartis, Sun Pharma, and Valeant; and has served as a speaker for AbbVie, Celgene, Eli Lilly, Janssen Biotech, and Novartis. Dr Colston, Dr Sekaran, Ms Linaberry, and Dr Banerjee are employees of and shareholders in Bristol Myers Squibb. Dr Throup and Dr Kundu were employees of and shareholders in Bristol Myers Squibb at the time of study conduct. Dr Papp has served on a speakers bureau for AbbVie, Amgen, Astellas, Celgene, Eli Lilly, Galderma, Janssen, Kyowa Hakko Kirin, Leo Pharma, Merck Sharp & Dohme, Novartis, Pfizer, and Valeant; has received grant/research support from AbbVie, Akros, Allergan, Amgen, Anacor, Arcutis, AstraZeneca, Baxalta, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Coherus, Dermira, Dow Pharma, Eli Lilly, Galderma, Genentech, GlaxoSmithKline, Janssen, Kyowa Hakko Kirin, Leo Pharma, MedImmune, Meiji Seika Pharma, Merck Serono, Novartis, Pfizer, Regeneron, Roche, Sanofi Genzyme, Takeda, UCB, and Valeant; has served as a consultant for AbbVie, Akros, Amgen, Arcutis, Astellas, AstraZeneca, Baxalta, Baxter, Boehringer Ingelheim, Bristol Myers Squibb, CanFite, Celgene, Coherus, Dermira, Dow Pharma, Eli Lilly, Forward Pharma, Galderma, Genentech, Janssen, Kyowa Hakko Kirin, Leo Pharma, Meiji Seika Pharma, Merck Serono, Merck Sharp & Dohme, Mitsubishi Pharma, Novartis, Pfizer, Regeneron, Roche, Sanofi Genzyme, Takeda, UCB, and Valeant; has received honoraria from AbbVie, Akros, Amgen, Baxter, Boehringer Ingelheim, Celgene, Coherus, Eli Lilly, Forward Pharma, Galderma, GlaxoSmithKline, Janssen, Kyowa Hakko Kirin, Merck Serono, Merck Sharp & Dohme, Novartis, Pfizer, Takeda, UCB, and Valeant; and has served as scientific officer or on a steering committee/advisory board for AbbVie, Akros, Amgen, Anacor, Astellas, Baxter, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Dow Pharma, Eli Lilly, Galderma, Janssen, Kyowa Hakko Kirin, Merck Serono, Merck Sharp & Dohme, Novartis, Pfizer, Regeneron, Sanofi Genzyme, and Valeant., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

TYK2, a member of the JAK family of proximal membrane-bound tyrosine kinases, has emerged as an attractive target for the treatment of autoimmune diseases. Herein, we report the discovery of first-in-class potent and subtype-selective TYK2 degraders. By conjugating a TYK2 ligand from a known allosteric TYK2 inhibitor with a VHL ligand as the E3 ligase ligand via alkyl linkers of various lengths, we rapidly identified TYK2 degrader 5 with moderate TYK2 degradation activity. Degrader 5 induced TYK2 degradation without affecting the protein level of subtype kinases (JAK1, JAK2, and JAK3) in Jurkat cellular assays. Furthermore, modifying the TYK2 ligand moiety of degrader 5 yielded the more potent TYK2 degrader 37 with retained selectivity for JAKs. Our subtype-selective TYK2 degraders represent valuable chemical probes for investigating the biology of TYK2 degradation., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ASKA Pharmaceutical Company Limited has filed patent application on the TYK2 degraders described in this study. All authors are employees of ASKA Pharmaceutical Company Limited., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This randomized, double-blind, single- and multiple-ascending dose study assessed the pharmacokinetics (PKs), pharmacodynamics, and safety of deucravacitinib (Sotyktu™), a selective and potent small-molecule inhibitor of tyrosine kinase 2, in 100 (75 active, 25 placebo) healthy volunteers (NCT02534636). Deucravacitinib was rapidly absorbed, with a half-life of 8-15 h, and 1.4-1.9-fold accumulation after multiple dosing. Deucravacitinib inhibited interleukin (IL)-12/IL-18-induced interferon (IFN)γ production ex vivo in a dose- and concentration-dependent manner. Following in vivo challenge with IFNα-2a, deucravacitinib demonstrated dose-dependent inhibition of lymphocyte count decreases and expression of 53 IFN-regulated genes. There were no serious adverse events (AEs); the overall frequency of AEs was similar in the deucravacitinib (64%) and placebo (68%) groups. In this first-in-human study, deucravacitinib inhibited IL-12/IL-23 and type I IFN pathways in healthy volunteers, with favorable PK and safety profiles. Deucravacitinib is a promising therapeutic option for immune-mediated diseases, including Crohn's disease, psoriasis, psoriatic arthritis, and systemic lupus erythematosus., (© 2022 Bristol Myers Squibb. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Background: Atopic dermatitis (AD) is a prevalent inflammatory, pruritic skin disease. The Janus kinase (JAK) pathway is a treatment target., Objectives: To assess the efficacy, safety and pharmacokinetics of topical cream brepocitinib, a small-molecule tyrosine kinase 2 (TYK2)/JAK1 inhibitor, in participants with mild-to-moderate AD., Methods: In this phase IIb, double-blind, dose-ranging study, participants were randomized to receive one of eight treatments for 6 weeks: brepocitinib 0·1% once daily (QD), 0·3% QD or twice daily (BID), 1·0% QD or BID, 3·0% QD, or vehicle QD or BID. The primary endpoint was the percentage change from baseline in the Eczema Area and Severity Index (EASI) total score at week 6. Adverse events (AEs) were monitored., Results: Overall, 292 participants were enrolled and randomized. The brepocitinib 1% QD and 1% BID groups achieved statistically significantly greater (with multiplicity-adjusted P < 0·05 due to Hochberg's step-up method) percentage reductions from baseline in EASI total score at week 6 [least squares mean (90% confidence interval, CI): QD: -70·1 (-82·1 to -58·0); BID: -75·0 (-83·8 to -66·2)] compared with respective vehicle [QD: -44·4 (-57·3 to -31·6); BID: -47·6 (-57·5 to -37·7)]. There was not a dose-dependent trend in AE frequency, and there were no serious AEs or deaths., Conclusions: Topical brepocitinib is effective and well tolerated in participants with mild-to-moderate AD. What is already known about this topic? Janus kinase (JAK) inhibitors are in development for treatment of atopic dermatitis (AD). The tyrosine kinase 2 and JAK 1 inhibition by brepocitinib may bring a new profile for topical JAK inhibitors for treatment of mild-to-moderate AD. What does this study add? Topical brepocitinib can provide rapid, effective symptom reduction, and could offer a novel alternative to current topical treatments for mild-to-moderate AD., (© 2022 Pfizer Inc and The Authors. British Journal of Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)

Background: Psoriasis treatments lack durable efficacy and have inconvenient administration, highlighting the need for new therapies., Objective: To evaluate the efficacy and safety of tyrosine kinase 2 inhibitor, PF-06826647, in moderate-to-severe plaque psoriasis., Methods: This phase 2b, double-blind study randomized participants to oral, once-daily PF-06826647 (1:1:2:2:2) 50:100:200:400 mg:placebo (16 weeks), then 200 or 400 mg (24 weeks) (NCT03895372). The primary end point was a proportion of participants achieving psoriasis area severity index (PASI) 90 at week 16. Secondary end points (PASI50/75/90/100; Physician's Global Assessment) and safety were assessed to week 40., Results: Overall, 178 participants were treated. A significantly greater proportion of participants (risk difference % [90% CI]) achieved PASI90 in the 200-mg (33.0 [18.0, 47.1], P = .0004) and 400-mg (46.5 [30.6, 60.6], P < .0001; week 16) groups versus placebo. Significant increases from placebo were observed for all secondary end points (200 and 400 mg; weeks 6-16; P < .05); increases were evident to week 40 (categorical data). PF-06826647 was well tolerated and most treatment-emergent adverse events were mild/moderate. Eighteen participants discontinued due to treatment-emergent adverse events (14 arising from laboratory abnormalities)., Limitations: Limitations included the large proportion of White males and non-placebo-controlled extension., Conclusion: PF-06826647 200 and 400 mg once daily showed significant efficacy versus placebo at week 16 and was well tolerated over 40 weeks., Competing Interests: Conflicts of interest Drs Singh, Tarabar, Peeva, Vincent and Gale and Authors Pradhan and Roberts are employees of, and hold stock in, Pfizer Inc. Dr Tehlirian is a previous employee of, and holds stock in, Pfizer Inc., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Psoriasis, a chronic inflammatory disease dependent on the IL-23/T H 17 pathway, is initiated through plasmacytoid dendritic cell activation and type I IFN induction in the skin. Deucravacitinib, a selective tyrosine kinase 2 (TYK2) inhibitor, blocks IL-23, IL-12, and type I IFN signaling in cellular assays., Objective: We investigated changes in IL-23/T H 17 and type I IFN pathway biomarkers and gene responses as well as measures of selectivity for TYK2 over Janus kinases (JAKs) 1-3 in patients with moderate to severe psoriasis receiving deucravacitinib., Methods: Deucravacitinib was evaluated in a randomized, placebo-controlled, dose-ranging trial. Biopsy samples from nonlesional (day 1) and lesional skin (days 1, 15, and 85) were assessed for changes in IL-23/IL-12 and type I IFN pathway biomarkers by quantitative reverse-transcription polymerase chain reaction, RNA sequencing, and immunohistochemistry. Laboratory markers were measured in blood. Percentage change from baseline in Psoriasis Area and Severity Index (PASI) score was assessed., Results: IL-23 pathway biomarkers in lesional skin returned toward nonlesional levels dose-dependently with deucravacitinib. IFN and IL-12 pathway genes were normalized. Markers of keratinocyte dysregulation, keratin-16, and β-defensin genes approached nonlesional levels with effective doses. Select laboratory parameters affected by JAK1-3 inhibition were not affected by deucravacitinib. Greater improvements in PASI scores, correlated with biomarker changes, were seen with the highest doses of deucravacitinib versus lower doses or placebo., Conclusion: Robust clinical efficacy with deucravacitinib treatment was associated with decreases in IL-23/T H 17 and IFN pathway biomarkers. The lack of effect seen on biomarkers specific to JAK1-3 inhibition supports selectivity of deucravacitinib for TYK2; larger confirmatory studies are needed., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Due to the high homology of the ATP sites of the JAK family, the development of selective inhibitors for a certain JAK isoform is extremely challenging. Our strategy to achieve high selectivity for TYK2 relies on targeting the TYK2 pseudokinase (JH2) domain. Based on the clinical compound BMS-986165, through structure-activity relationship studies, a class of acyl compounds with excellent TYK2 inhibitory activity and selectivity to other subtypes of the JAK family was discovered., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Chaoying Cheng et al.)

Introduction: Tyrosine kinase 2 (TYK2) is a member of the JAK family class of kinases that is responsible for mediating the immune response to IL-12, IL-23, and IFNα. The therapeutic value of targeting this pathway in autoimmune diseases is supported by human genetics and multiple companies are developing small-molecule inhibitors as potential new treatments., Areas Covered: This article seeks to give a comprehensive review of the applications related to selective small-molecule TYK2 inhibition since the last publication in this journal in 2019. Recent regulatory activity, emerging clinical data, and new companies entering the clinic with selective TYK2 inhibitors will also be discussed., Expert Opinion: Over the past 3 years there has been an increase in the number of companies and patent applications claiming selective TYK2 inhibitors. Deucravacitinib, an allosteric TYK2 inhibitor discovered by BMS, is the most advanced molecule in clinical development and in 2021, it received positive phase 3 data for the treatment of plaque psoriasis. . This development has spurred a renewed interest in targeting TYK2 with selective inhibitors and several new molecules have recently entered phase 1 trials. The research interest in this area is likely to further increase as additional clinical data with deucravacitinib and other TYK2 inhibitors continue to emerge.

In this study, we described a series of 2,8-diazaspiro[4.5]decan-1-one derivatives as selective TYK2/JAK1 inhibitors. Systematic exploration of the structure-activity relationship through the introduction of spirocyclic scaffolds based on the reported selective TYK2 inhibitor 14l led to the discovery of the superior derivative compound 48 . Compound 48 showed excellent potency on TYK2/JAK1 kinases with IC 50 values of 6 and 37 nM, respectively, and exhibited more than 23-fold selectivity for JAK2. Compound 48 also demonstrated excellent metabolic stability and more potent anti-inflammatory efficacy than tofacitinib in acute ulcerative colitis models. Moreover, the excellent anti-inflammatory effect of compound 48 was mediated by regulating the expression of related TYK2/JAK1-regulated genes, as well as the formation of Th1, Th2, and Th17 cells. Taken together, these findings suggest that compound 48 is a selective dual TYK2/JAK inhibitor, deserving to be developed as a clinical candidate.

Conventional systemic and biologic agents are the mainstay of inflammatory bowel disease (IBD) management; however, many of these agents are associated with loss of clinical response, highlighting the need for effective, novel targeted therapies. Janus kinase (JAK) 1-3 and tyrosine kinase 2 (TYK2) mediate signal transduction events downstream of multiple cytokine receptors that regulate targeted gene transcription, including the interleukin-12, interleukin-23, and type I interferon receptors for TYK2. This review summarizes the role of TYK2 signaling in IBD pathogenesis, the differential selectivity of TYK2 inhibitors, and the potential clinical implications of TYK2 inhibition in IBD. A PubMed literature review was conducted to identify studies of JAK1-3 and TYK2 inhibitors in IBD and other immune-mediated inflammatory diseases. Key efficacy and safety information was extracted and summarized. Pan-JAK inhibitors provide inconsistent efficacy in patients with IBD and are associated with toxicities resulting from a lack of selectivity at therapeutic dosages. Selective inhibition of TYK2 signaling via an allosteric mechanism, with an agent that binds to the regulatory (pseudokinase) domain, may reduce potential toxicities typically associated with JAK1-3 inhibitors. Deucravacitinib, a novel, oral, selective TYK2 inhibitor, and brepocitinib and PF-06826647, TYK2 inhibitors that bind to the active site in the catalytic domain, are in development for IBD and other immune-mediated inflammatory diseases. Allosteric TYK2 inhibition is more selective than JAK1-3 inhibition and has the potential to limit toxicities typically associated with JAK1-3 inhibitors. Future studies will be important in establishing the role of selective, allosteric TYK2 inhibition in the management of IBD., (© 2021 Crohn’s & Colitis Foundation. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation.)

JAKs are intracellular protein tyrosine kinases that, through activation of STATs, are responsible for signal transduction pathways that regulate cellular responses to numerous cytokines, growth factors and hormones in many different cells. JAK-STAT signaling plays a key role in regulating immune function, and cytokines - such as IL-23, IL-12 and type I interferons - are central to the pathogenesis of autoimmune diseases, including psoriasis, inflammatory bowel disease and systemic lupus erythematosus. Here the authors review the evidence for targeting TYK2 as a more specific approach to treating these conditions. TYK2 inhibitors are clinically effective in autoimmune and inflammatory diseases and may avoid some of the complications reported with nonselective JAK inhibitors.

Atopic dermatitis (AD) is chronic, pruritic, inflammatory skin disease that affects a significant portion of the population in industrialized nations. For nonresponders to conventional therapies, AD can significantly reduce sleep quality and quality of life. AD pathogenesis is multifactorial and involves multiple immune pathways, with recent evidence of T helper (Th)2, Th17 and Th22 axis attenuation in various AD endotypes and racial subtypes. Inhibition of the conserved Janus kinase (JAK) signalling pathway represents a promising therapeutic avenue to reduce the activation of multiple proinflammatory mediators involved in AD pathogenesis. JAK inhibitors exist in both oral and topical forms with variable specificity for the receptor tyrosine kinases JAK1, JAK2, JAK3 and tyrosine kinase 2. Oral formulations include abrocitinib, upadacitinib, baricitinib and gusacitinib, and are most appropriate for patients with moderate to severe AD. Emerging topical formulation in development include ruxolitinib and deglocitinib, which may be used in patients with localized AD and also adjunctively with systemic therapy in patients with more severe disease. With observed rapidity in itch relief and accompanying dramatic reduction in inflammatory lesion count, JAK inhibitors represent a promising new treatment to revolutionize the management of AD., (© 2021 British Association of Dermatologists.)

The predominant assay detection methodologies used for enzyme inhibitor identification during early-stage drug discovery are fluorescence-based. Each fluorophore has a characteristic fluorescence decay, known as the fluorescence lifetime, that occurs throughout a nanosecond-to-millisecond timescale. The measurement of fluorescence lifetime as a reporter for biological activity is less common than fluorescence intensity, even though the latter has numerous issues that can lead to false-positive readouts. The confirmation of hit compounds as true inhibitors requires additional assays, cost, and time to progress from hit identification to lead drug-candidate optimization. To explore whether the use of fluorescence lifetime technology (FLT) can offer comparable benefits to label-free-based approaches such as RapidFire mass spectroscopy (RF-MS) and a superior readout compared to time-resolved fluorescence resonance energy transfer (TR-FRET), three equivalent assays were developed against the clinically validated tyrosine kinase 2 (TYK2) and screened against annotated compound sets. FLT provided a marked decrease in the number of false-positive hits when compared to TR-FRET. Further cellular screening confirmed that a number of potential inhibitors directly interacted with TYK2 and inhibited the downstream phosphorylation of the signal transducer and activator of transcription 4 protein (STAT4).

Inflammatory diseases are frequently treated with Janus kinase (JAK) inhibitors to diminish cytokine signaling. These treatments can lead to inadvertent immune suppression and may increase the risk of viral infection. Tyrosine kinase 2 (TYK2) is a JAK family member required for efficient type I interferon (IFN-α/β) signaling. We report here that selective TYK2 inhibition preferentially blocked potentially detrimental type I IFN signaling, whereas IFN-λ-mediated responses were largely preserved. In contrast, the clinically used JAK1/2 inhibitor baricitinib was equally potent in blocking IFN-α/β- or IFN-λ-driven responses. Mechanistically, we showed that epithelial cells did not require TYK2 for IFN-λ-mediated signaling or antiviral protection. TYK2 deficiency diminished IFN-α-induced protection against lethal influenza virus infection in mice but did not impair IFN-λ-mediated antiviral protection. Our findings suggest that selective TYK2 inhibitors used in place of broadly acting JAK1/2 inhibitors may represent a superior treatment option for type I interferonopathies to counteract inflammatory responses while preserving antiviral protection mediated by IFN-λ., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Cytokine signaling, especially interferon (IFN) signaling is closely linked to several aspects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. During initial SARS-CoV-2 infection, symptomatic patients present with impaired type I/III IFN-mediated antiviral responses. Interestingly, IFNs regulate the cellular entry receptor for SARS-CoV-2 on epithelial and endothelial cells. As reported recently, critically ill COVID-19 patients show genetic polymorphisms in one IFN receptor gene (IFNRA2) and in a gene locus near the Janus kinase (JAK) TYK2, which is key for IFN, interleukin (IL)-12 and IL-23 signaling, and T helper (Th) 1/Th17 cell-mediated antiviral immune responses. In the advanced stage of the disease, critically ill COVID-19 patients develop a cytokine storm where many inflammatory mediators using the JAK/STAT signaling pathway such as IL-6, IFN-γ, the granulocyte colony-stimulating factor (G-CSF) or IL-2, and chemokines result in an influx of macrophages and neutrophils damaging the lung tissue. The knowledge on the cytokine and JAK/STAT signaling pathways in severe COVID-19 disease explains the promising first results with JAK inhibitors like baricitinib, which not only dampen the inflammation but in the case of baricitinib also affect virus replication and endocytosis in target cells. Here, we summarize the current immunological associations of SARS-CoV-2 infection with cytokine signaling, the JAK/STAT pathway, and the current clinical stage of JAK inhibitors for improving severe COVID-19 disease., (© 2021 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

Background and Aims: Tyrosine kinase 2 [TYK2] is required for the signalling of key cytokines in the pathogenesis of inflammatory bowel disease [IBD]. We assessed the efficacy of a novel selective TYK2 inhibitor [TYK2i] in experimental colitis, using pharmacological and genetic tools., Methods: At onset of T cell transfer colitis, RAG1-/- mice received vehicle or TYK2i daily by oral gavage. T cells lacking TYK2 kinase activity [TYK2KE] were used to confirm selectivity of the inhibitor. To this end, RAG1-/- or RAG1-/-TYK2KE animals were transferred with either wild type [WT] or TYK2KE-CD45RBhigh colitogenic T cells. Loss of body weight, endoscopic disease, the disease activity index [DAI], and histopathology scores were recorded. Tissues were analysed ex vivo for lymphocyte populations by flow cytometry. The impact of TYK2 inhibition on human DC-T cell interactions were studied using autologous Revaxis specific T cell assays., Results: TYK2i [70 mg/kg] prevented weight loss and limited endoscopic activity during T cell transfer colitis. TYK2i [70 mg/kg] decreased DAI. Whereas transfer of WT T cells into RAG-/-TYK2KE hosts induced colitis, TYK2KE T cells transferred into RAG1-/-TYK2KErecipients failed to do so. Ex vivo analysis showed a decrease in colon tissue Th1 cells and an increase in Th17 cells upon transfer of TYK2KE-CD45RBhigh cells. In human antigen-triggered T cells, TYK2i displayed reduced Th1 differentiation, similar to murine Th1 cells., Conclusions: Oral administration of TYK2i, as well as transfer of T cells lacking TYK2 activity, reduced human Th1 differentiation and ameliorated the course of murine T cell transfer colitis. We conclude that TYK2 is a promising drug target for the treatment of IBD., (© The Author(s) 2020. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation.)

Selective inhibition of tyrosine kinase 2 (TYK2) may offer therapeutic promise in inflammatory conditions, with its role in downstream pro-inflammatory cytokine signaling. In this first-in-human study, we evaluated the safety, tolerability, and pharmacokinetics (PK) of a novel TYK2 inhibitor, PF-06826647, in healthy participants. This phase I, randomized, double-blind, placebo-controlled, parallel-group study included two treatment periods (single ascending dose (SAD) and multiple ascending dose (MAD)) in healthy participants and a cohort of healthy Japanese participants receiving 400 mg q.d. or placebo in the MAD period (NCT03210961). Participants were randomly assigned to PF-06826647 or placebo (3:1). Participants received a single oral study drug dose of 3, 10, 30, 100, 200, 400, or 1,600 mg (SAD period), then 30, 100, 400, or 1,200 mg q.d. or 200 mg b.i.d. for 10 days (MAD period). Safety (adverse events (AEs), vital signs, and clinical laboratory parameters), tolerability, and PK were assessed. Overall, 69 participants were randomized to treatment, including six Japanese participants. No deaths, serious AEs, severe AEs, or AEs leading to dose reduction or temporary/permanent discontinuation were observed. All AEs were mild in severity. No clinically relevant laboratory abnormalities or changes in vital signs were detected. PF-06826647 was rapidly absorbed with a median time to maximum plasma concentration of 2 hours in a fasted state, with modest accumulation (< 1.5-fold) after multiple dosing and low urinary recovery. PF-06826647 was well-tolerated, with an acceptable safety profile for doses up to 1,200 mg q.d. for 10 days, supporting further testing in patients., (© 2020 Pfizer Inc. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of the American Society for Clinical Pharmacology and Therapeutics.)

TYK2 mediates signaling of IL-23, IL-12, and Type I IFN-driven responses that are critical in immune-mediated diseases. Herein, we report the design, synthesis, and structure-activity relationships (SARs) of 3-(4-(2-((1 H -indol-5-yl)amino)-5-fluoropyrimidin-4-yl)-1 H -pyrazol-1-yl)propanenitrile derivatives as selective TYK2 inhibitors. Among them, compound 14l exhibited acceptable TYK2 inhibition with an IC 50 value of 9 nM, showed satisfactory selectivity characteristics over the other three homologous JAK kinases, and performed good functional potency in the JAK/STAT signaling pathway on lymphocyte lines and human whole blood. In liver microsomal assay studies, the clearance rate and half-life of 14l were 11.4 mL/min/g and 121.6 min, respectively. Furthermore, in a dextran sulfate sodium colitis model, 14l reduced the production of pro-inflammatory cytokines IL-6 and TNF-α and improved the inflammation symptoms of mucosal infiltration, thickening, and edema. Taken together, 14l was a selective TYK2 inhibitor and could be used to treat immune diseases deserving further investigation.

A search for structurally diversified Tyk2 JH2 ligands from 6 (BMS-986165), a pyridazine carboxamide-derived Tyk2 JH2 ligand as a clinical Tyk2 inhibitor currently in late development for the treatment of psoriasis, began with a survey of six-membered heteroaryl groups in place of the N -methyl triazolyl moiety in 6 . The X-ray co-crystal structure of an early lead ( 12 ) revealed a potential new binding pocket. Exploration of the new pocket resulted in two frontrunners for a clinical candidate. The potential hydrogen bonding interaction with Thr599 in the pocket was achieved with a tertiary amide moiety, confirmed by the X-ray co-crystal structure of 29 . When the diversity search was extended to nicotinamides, a single fluorine atom addition was found to significantly enhance the permeability, which directly led to the discovery of 7 (BMS-986202) as a clinical Tyk2 inhibitor that binds to Tyk2 JH2. The preclinical studies of 7 , including efficacy studies in mouse models of IL-23-driven acanthosis, anti-CD40-induced colitis, and spontaneous lupus, will also be presented.

Tyrosine kinase 2 (Tyk2) is a member of the Janus family of protein tyrosine kinases (Jaks). Tyk2 associates with interferon (IFN)-α, IFN-β, interleukin (IL)-6, IL-10, IL-12, and IL-23 receptors and mediates their downstream signaling pathways. Based on our data using Tyk2-deficient mice and cells, Tyk2 plays crucial roles in the differentiation, maintenance, and function of T helper 1 (Th1) and Th17 cells, and its dysregulation may promote autoimmune and/or inflammatory diseases. IFN-α-induced growth inhibition of B lymphocyte progenitors is dependent on Tyk2-mediated signals to regulate death-associated protein (Daxx) nuclear localization and Daxx-promyelocytic leukemia protein interactions. Tyk2-deficient mice show impaired constitutive production of type I IFNs by macrophages under steady-state conditions. When heat-killed Cutibacterium acnes is injected intraperitoneally, Tyk2-deficient mice show less granuloma formation through enhanced prostaglandin E 2 and protein kinase A activities, leading to high IL-10 production by macrophages. Thus, Tyk2 is widely involved in the immune and inflammatory response at multiple events; therefore, Tyk2 is likely to be a suitable target for treating patients with autoimmune and/or chronic inflammatory diseases. Clinical trials of Tyk2 inhibitors have shown higher response rates and improved tolerability in the treatment of patients with psoriasis and inflammatory bowel diseases. Taken together, Tyk2 inhibition has great potential for clinical application in the management of a variety of diseases.

Trial Design: We report results from a phase IIa study of efficacy and safety of PF-06700841, an oral TYK2/Jak1 inhibitor, in patients with moderate-to-severe plaque psoriasis (NCT02969018)., Methods: Patients were randomized to PF-06700841 30 mg once daily (QD), 60 mg QD, or placebo (4-week induction), followed by 10 mg QD, 30 mg QD, 100 mg once weekly, or placebo (8-week maintenance). The primary endpoint was week 12 change from baseline in PASI score. Secondary endpoints were the proportion of patients achieving 75% and 90% reduction from baseline PASI at week 12., Results: In total, 212 patients in 35 sites were treated; mean (SD) baseline PASI score was 20.8 (7.68). Decreases in PASI at week 12 were statistically significant compared with placebo in five treatment groups. The greatest change from baseline (least squares mean change -17.3 [95% confidence interval, -20.0 to -14.6]) was observed in the 30-mg QD continuous treatment group. Overall, 136 patients experienced treatment-emergent adverse events, including six serious adverse events in five patients and 13 discontinuations in treatment groups because of adverse events. No herpes zoster cases or major adverse cardiac events including thromboembolic events occurred., Conclusions: PF-06700841 was generally effective and well tolerated in patients with moderate-to-severe plaque psoriasis., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Tyrosine kinase 2 (TYK2) is a member of the JAK kinase family that regulates signal transduction downstream of receptors for the IL-23/IL-12 pathways and type I interferon family, where it pairs with JAK2 or JAK1, respectively. On the basis of human genetic and emerging clinical data, a selective TYK2 inhibitor provides an opportunity to treat autoimmune diseases delivering a potentially differentiated clinical profile compared to currently approved JAK inhibitors. The discovery of an ATP-competitive pyrazolopyrazinyl series of TYK2 inhibitors was accomplished through computational and structurally enabled design starting from a known kinase hinge binding motif. With understanding of PK/PD relationships, a target profile balancing TYK2 potency and selectivity over off-target JAK2 was established. Lead optimization involved modulating potency, selectivity, and ADME properties which led to the identification of the clinical candidate PF-06826647 ( 22 ).

Introduction: Janus kinases inhibitors (JAKi) are new small molecules recently introduced in the armamentarium of treatments for Inflammatory Bowel Disease (IBD). Janus Kinases (JAK) are tyrosine kinases that act by linkage with different intracellular receptors, regulating cytokines gene transcription implicated in the inflammatory burden seen in IBD patients., Areas Covered: A comprehensive literature search was performed to retrieve studies on JAKi and IBD to discuss the latest developments and how the selectivity of these drugs is changing the natural course of IBD., Expert Opinion: Available data on efficacy and safety of JAKi in IBD are highly encouraging and because of their selectivity, these drugs might become among the foremost options in the treatment algorithm.

The IL-23/T helper type 17 cell axis is a target for psoriasis. The TYK2/Janus kinase 1 inhibitor PF-06700841 will directly suppress TYK2-dependent IL-12 and IL-23 signaling and Janus kinase 1-dependent signaling in cells expressing these signaling molecules, including T cells and keratinocytes. This clinical study sought to define the inflammatory gene and cellular pathways through which PF-06700841 improves the clinical manifestations of psoriasis. Patients (n = 30) with moderate-to-severe psoriasis were randomized to once-daily 30 mg (n = 14) or 100 mg (n = 7) PF-06700841 or placebo (n = 9) for 28 days. Biopsies were taken from nonlesional and lesional skin at baseline and weeks 2 and 4. Changes in the psoriasis transcriptome and genes induced by IL-17 in keratinocytes were evaluated with microarray profiling and reverse transcriptase-PCR. Reductions in IL-17A, IL-17F, and IL-12B mRNA were observed as early as 2 weeks and approximately 70% normalization of lesional gene expression after 4 weeks. Immunohistochemistry showed significant decreases in markers of keratinocyte activation, epidermal thickness, KRT16 and Ki-67 expression, and immune cell infiltrates CD3 + /CD8 + (T cells) and CD11c (dendritic cells) after 2 weeks of treatment, corresponding with improvement in histologic score. PF-06700841 improves clinical symptoms of chronic plaque psoriasis by inhibition of proinflammatory cytokines that require TYK2 and Janus kinase 1 for signal transduction., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Translation of modulation of drug target activity to therapeutic effect is a critical aspect for all drug discovery programs. In this work we describe the profiling of a non-receptor tyrosine-protein kinase (TYK2) inhibitor which shows a functionally relevant potency shift between human and preclinical species (e.g. murine, dog, macaque) in both biochemical and cellular assays. Comparison of the structure and sequence homology of TYK2 between human and preclinical species within the ATP binding site highlights a single amino acid (I960 → V) responsible for the potency shift. Through TYK2 kinase domain mutants and a TYK2 980I knock-in mouse model, we demonstrate that this single amino acid change drives a functionally relevant potency difference that exists between human and all evaluated preclinical species, for a series of TYK2 inhibitors which target the ATP binding site.

Herein, we disclose a new series of TYK2/ JAK1 inhibitors based upon a 3.1.0 azabicyclic substituted pyrimidine scaffold. We illustrate the use of structure-based drug design for the initial design and subsequent optimization of this series of compounds. One advanced example 19 met program objectives for potency, selectivity and ADME, and demonstrated oral activity in the adjuvant-induced arthritis rat model., 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 Ltd. All rights reserved.)

Spondyloarthritis (SpA) represents a family of inflammatory diseases of the spine and peripheral joints. Ankylosing spondylitis (AS) is the prototypic form of SpA in which progressive disease can lead to fusion of the spine. Therapeutically, knowledge of type 3 immunity has translated into the development of IL-23- and IL-17A-blocking antibodies for the treatment of SpA. Despite being able to provide symptomatic control, the current biologics do not prevent the fusion of joints in AS patients. Thus, there is an unmet need for disease-modifying drugs. Genetic studies have linked the Janus kinase TYK2 to AS. TYK2 is a mediator of type 3 immunity through intracellular signaling of IL-23. Here, we describe and characterize a potentially novel small-molecule inhibitor of TYK2 that blocked IL-23 signaling in vitro and inhibited disease progression in animal models of SpA. The effect of the inhibitor appears to be TYK2 specific, using TYK2-inactive mice, which further revealed a duality in the induction of IL-17A and IL-22 by IL-23. Specifically, IL-22 production was TYK2/JAK2/STAT3 dependent, while IL-17A was mostly JAK2 dependent. Finally, we examined the effects of AS-associated TYK2 SNPs on TYK2 expression and function and correlated them with AS disease progression. This work provides evidence that TYK2 inhibitors have great potential as an orally delivered therapeutic for SpA.

Despite advances in the treatment of psoriasis, there is an unmet need for effective and safe oral treatments. The Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) pathway plays a significant role in intracellular signalling of cytokines of numerous cellular processes, important in both normal and pathological states of immune-mediated inflammatory diseases. Particularly in psoriasis, where the interleukin (IL)-23/IL-17 axis is currently considered the crucial pathogenic pathway, blocking the JAK-STAT pathway with small molecules would be expected to be clinically effective. However, relative non-specificity and low therapeutic index of the available JAK inhibitors have delayed their integration into the therapeutic armamentarium of psoriasis. Current research appears to be focused on Tyrosine kinase 2 (TYK2), the first described member of the JAK family. Data from the Phase II trial of BMS-986165-a selective TYK2 inhibitor-in psoriasis have been published and clinical results are encouraging, with a large Phase III programme ongoing. Further, the selective TYK2 inhibitor PF-06826647 is being tested in moderate-to-severe psoriasis in a Phase II clinical trial. Brepocitinib, a potent TYK2/JAK1 inhibitor, is also being evaluated, as both oral and topical treatment. Results of studies with TYK2 inhibitors will be important in assessing the clinical efficacy and safety of these drugs and their place in the therapeutic armamentarium of psoriasis. This article reviews current data on the impact of JAK inhibitors in the treatment of adult patients with moderate-to-severe psoriasis.

Herein we report an efficient method for the synthesis of a highly functionalized 2-pyrrolidinone, tert-butyl 3-cyano-3-cyclopropyl-2-oxopyrrolidine-4-carboxylate, from readily available starting materials. Utility of this compound was demonstrated in the synthesis of a novel series of macrocyclic Tyk2 inhibitors, leading to the identification of a potent and selective macrocyclic Tyk2 inhibitor (26)., 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 Ltd. All rights reserved.)

Small molecule JAK inhibitors have emerged as a major therapeutic advancement in treating autoimmune diseases. The discovery of isoform selective JAK inhibitors that traditionally target the catalytically active site of this kinase family has been a formidable challenge. Our strategy to achieve high selectivity for TYK2 relies on targeting the TYK2 pseudokinase (JH2) domain. Herein we report the late stage optimization efforts including a structure-guided design and water displacement strategy that led to the discovery of BMS-986165 ( 11 ) as a high affinity JH2 ligand and potent allosteric inhibitor of TYK2. In addition to unprecedented JAK isoform and kinome selectivity, 11 shows excellent pharmacokinetic properties with minimal profiling liabilities and is efficacious in several murine models of autoimmune disease. On the basis of these findings, 11 appears differentiated from all other reported JAK inhibitors and has been advanced as the first pseudokinase-directed therapeutic in clinical development as an oral treatment for autoimmune diseases.

As a member of the Janus (JAK) family of nonreceptor tyrosine kinases, TYK2 plays an important role in mediating the signaling of pro-inflammatory cytokines including IL-12, IL-23, and type 1 interferons. The nicotinamide 4 , identified by a SPA-based high-throughput screen targeting the TYK2 pseudokinase domain, potently inhibits IL-23 and IFNα signaling in cellular assays. The described work details the optimization of this poorly selective hit ( 4 ) to potent and selective molecules such as 47 and 48 . The discoveries described herein were critical to the eventual identification of the clinical TYK2 JH2 inhibitor (see following report in this issue). Compound 48 provided robust inhibition in a mouse IL-12-induced IFNγ pharmacodynamic model as well as efficacy in an IL-23 and IL-12-dependent mouse colitis model. These results demonstrate the ability of TYK2 JH2 domain binders to provide a highly selective alternative to conventional TYK2 orthosteric inhibitors.

TYK2 is a nonreceptor tyrosine kinase involved in adaptive and innate immune responses. A deactivating coding variant has previously been shown to prevent receptor-stimulated activation of this kinase and provides high protection from several common autoimmune diseases but without immunodeficiency. An agent that recapitulates the phenotype of this deactivating coding variant may therefore represent an important advancement in the treatment of autoimmunity. BMS-986165 is a potent oral agent that similarly blocks receptor-stimulated activation of TYK2 allosterically and with high selectivity and potency afforded through optimized binding to a regulatory domain of the protein. Signaling and functional responses in human T H 17, T H 1, B cells, and myeloid cells integral to autoimmunity were blocked by BMS-986165, both in vitro and in vivo in a phase 1 clinical trial. BMS-986165 demonstrated robust efficacy, consistent with blockade of multiple autoimmune pathways, in murine models of lupus nephritis and inflammatory bowel disease, supporting its therapeutic potential for multiple immune-mediated diseases., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)