Selective Tyrosine Kinase 2 (TYK2) Inhibition in Plaque Psoriasis.

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.

Comparative efficacy and safety of JAK/TYK2 inhibitors and other oral drugs for moderate-to-severe plaque psoriasis: Systematic review and network meta-analysis.

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.

Modifying T cell phenotypes using TYK2 inhibitor and its implications for the treatment of systemic lupus erythematosus.

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+TGFß 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.

Targeting TYK2 for Fighting Diseases: Recent Advance of TYK2 Inhibitors.

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.

Discovery of selective TYK2 inhibitors: Design, synthesis, in vitro and in silico studies of promising hits with triazolopyrimidinone scaffold.

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.

Discovery of GLPG3667, a Selective ATP Competitive Tyrosine Kinase 2 Inhibitor for the Treatment of Autoimmune Diseases.

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).

The Psoriasis Treatment Pipeline: An Overview and Update.

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.

TYK2 inhibition with deucravacitinib ameliorates erosive oral lichen planus.

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-É£ (IFN-É£) 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-É£ signalling. While some drugs such as abrocitinib, upadacitinib, tofacitinib directly interfere with IFN-É£ signalling through blockade of JAK1 and/or JAK2, deucravacitinib, a selective TYK-2 inhibitor indirectly interferes on IFN-É£ activation through interference with interleukin (IL)-12, a potent promotor for Th1/IFN-É£ 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.

Employing zero-inflated beta distribution in an exposure-response analysis of TYK2/JAK1 inhibitor brepocitinib in patients with plaque psoriasis.

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.

TYK2: an emerging therapeutic target in rheumatic disease.

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.

Deucravacitinib, a selective, allosteric tyrosine kinase 2 inhibitor, in scalp psoriasis: A subset analysis of two phase 3 randomized trials in plaque psoriasis.

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.

Oral small-molecule tyrosine kinase 2 and phosphodiesterase 4 inhibitors in plaque psoriasis: a network meta-analysis.

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_record.php?ID=CRD42022384859, identifier CRD42022384859.

English version of Japanese guidance for the use of oral Janus kinase inhibitors (JAK1 and TYK2 inhibitors) in the treatments of psoriasis.

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.

Efficacy and safety of the selective TYK2 inhibitor, deucravacitinib, in Japanese patients with moderate to severe plaque psoriasis: Subgroup analysis of a randomized, double-blind, placebo-controlled, global phase 3 trial.

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.

Discovery of a potent and subtype-selective TYK2 degrader based on an allosteric TYK2 inhibitor.

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.

Deucravacitinib versus placebo and apremilast in moderate to severe plaque psoriasis: Efficacy and safety results from the 52-week, randomized, double-blinded, phase 3 Program fOr Evaluation of TYK2 inhibitor psoriasis second trial.

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.

First-in-human study of deucravacitinib: A selective, potent, allosteric small-molecule inhibitor of tyrosine kinase 2.

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.

Efficacy and safety of topical brepocitinib for the treatment of mild-to-moderate atopic dermatitis: a phase IIb, randomized, double-blind, vehicle-controlled, dose-ranging and parallel-group study.

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.

Design, Synthesis and Activity Study of Pyridine Derivatives as Highly Effective and Selective TYK2 Inhibitors.

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.