JAK inhibitor selectivity: new opportunities, better drugs?

Cytokines function as communication tools of the immune system, serving critical functions in many biological responses and shaping the immune response. When cytokine production or their biological activity goes awry, the homeostatic balance of the immune response is altered, leading to the development of several pathologies such as autoimmune and inflammatory disorders. Cytokines bind to specific receptors on cells, triggering the activation of intracellular enzymes known as Janus kinases (JAKs). The JAK family comprises four members, JAK1, JAK2, JAK3 and tyrosine kinase 2, which are critical for intracellular cytokine signalling. Since the mid-2010s multiple JAK inhibitors have been approved for inflammatory and haematological indications. Currently, approved JAK inhibitors have demonstrated clinical efficacy; however, improved selectivity for specific JAKs is likely to enhance safety profiles, and different strategies have been used to accomplish enhanced JAK selectivity. In this update, we discuss the background of JAK inhibitors, current approved indications and adverse effects, along with new developments in this field. We address the issue of JAK selectivity and its relevance in terms of efficacy, and describe new modalities of JAK targeting, as well as new aspects of JAK inhibitor action.

Analysis of patient experiences regarding JAK inhibitors for atopic dermatitis, psoriasis, alopecia areata, and vitiligo.

The use of medications which target the JAK-STAT signaling pathway, also known as janus kinase (JAK) inhibitors, has rapidly increased in recent years. Patient perceptions, opinions, and concerns regarding the use of JAK inhibitors are largely uninvestigated. Our objective is to better understand patient concerns, reported side effects, and sentiments regarding the use of JAK inhibitors for dermatologic disease. The authors performed a cross-sectional analysis of the most frequented subreddits for dermatologic disease in which JAK inhibitors have obtained FDA approval (r/atopic dermatitis, r/psoriasis, r/alopecia areata, r/vitiligo, and r/eczeJAKS). The sentiment, central theme, and engagement level of each post was evaluated using previously utilized methods. Nine hundred twenty-three posts were analyzed, with the majority focusing on efficacy (433, 47%) and medication-related side effects (150, 16%). Other themes of interest to patients were Payment/Insurance (84, 9%), Study Results/News (69, 7%), Administration/Dosage (33, 4%), and Medication Interactions (31, 3%). The most frequently reported side effects were acne/folliculitis (24, 22%), nausea/gastrointestinal disturbance (11,10%), and fatigue/muscle aches (10, 9%). At the same time, the medication interactions garnering the most concern were sunscreens/facial moisturizers (5, 16%), topical calcineurin inhibitors (4, 13%), and Marijuana/THC (3, 9.%). This analysis highlights that patients are most concerned about the efficacy and side effects of JAK inhibitors in addition to issues regarding access to JAK inhibitors. Providers can use the insights gained from this study to address hesitancy better and guide comprehensive, patient-centered discussions with patients regarding JAK inhibitor use.

Humans are unreliable models of mouse disease.

In defying conventional views that dismissed itch as trivial, I persisted in studying basophils and ILC2s in human skin and atopic dermatitis. My research on JAK inhibitors for itch ultimately led to FDA-approved drugs. This is my story of disregarding categories and definitions-a story about an unconventional path in science that emphasizes innovation over conformity.

[JAK inhibitors for myelofibrosis: ruxolitinib and momelotinib].

Myelofibrosis should be diagnosed according to the WHO classification (2022, 5th Ed.) and International Consensus Conference 2022 criteria. Testing for driver mutations in the three genes JAK2, CALR, and MPL is recommended to ensure a definitive diagnosis. Ruxolitinib is the only JAK inhibitor currently approved in Japan, but momelotinib is under regulatory review. The MOMENTUM study showed similar spleen volume reduction at 24 weeks and MFSAF-TSS reduction as the COMFORT study of ruxolitinib. Momelotinib acts on ACVR1 and, therefore, improves anemia through suppression of hepcidin. Anemia and/or transfusion dependency are known to be associated with overall survival duration. Consequently, supportive care measures such as ESA and danazol in lieu of transfusion should be considered in addition to JAK inhibitor selection. Mean survival after discontinuation of JAK inhibitors is 11 to 14 months. Pacritinib (not approved in Japan) is suitable for MF patients with thrombocytopenia. JAK inhibitor selection and supportive care by ESA or danazol in lieu of transfusion should be considered. Many classes of drugs other than JAK inhibitors for myelofibrosis are under investigation.

Janus kinase inhibitors and adverse events of acne in dermatologic indications: a systematic review and network meta-analysis.

Background: The occurrence of acne in patients treated with Janus kinase (JAK) inhibitors for skin diseases is a potential issue, which may reduce treatment adherence.Purpose: To systematically analyzes randomized clinical trials (RCTs) of JAK inhibitors in dermatological indications for the risk of acne as an adverse event.Methods: A meta-analysis of odds ratios (ORs) for acne incidence was conducted. Data were quantitatively synthesized using random-effects meta-analysis. Surface under the cumulative ranking curve (SUCRA) values representing the relative ranking probabilities of treatments were obtained. Analyses were performed using R statistical software version 4.4.0.Results: A total of 11,396 patients were included from 24 studies. The incidence of acne for JAK inhibitors was ranked according to the SUCRA as follows: JAK1 inhibitors > TYK2 inhibitors > combined JAK1 and JAK2 inhibitors > combined JAK1 and TYK2 inhibitors > JAK3 + TEC inhibitors > pan-JAK inhibitors. ORs were higher for longer durations of drug use and larger dosages. Subgroup analyses by disease indication revealed increased ORs for psoriasis (5.52 [95% CI, 1.39-21.88]), vitiligo (4.15 [95% CI, 1.27-13.58]), alopecia areata (3.86 [95% CI, 1.58-9.42]), and atopic dermatitis (2.82 [95% CI, 1.75-4.54]). The use of JAK inhibitors in patients with systemic lupus erythematosus (SLE) may not significantly increase the incidence of acne.Conclusions: There are higher rates of acne following treatment with JAK inhibitors for dermatologic indications, particularly with longer durations and larger dosages. Pan-JAK inhibitors exhibit the lowest incidence of acne.

Use of Janus kinase inhibitors before and after European Medicines Agency safety recommendations: a retrospective study.

Background: Safety recommendations for Janus kinase inhibitors (JAKi) issued by the European Medical Agency (EMA) in 2023 could potentially influence treatment patterns for rheumatoid arthritis (RA) drugs, but little is known about the impact of these recommendations in routine clinical care. Methods: We retrospectively analyzed the German RHADAR rheumatology database for adult patients with RA and documentation of a new therapy with a JAKi, tumor necrosis factor inhibitor (TNFi), or interleukin-6 receptor inhibitor (IL-6Ri). Data were grouped into half-yearly intervals from quarter (Q)2/2020 to Q3/2023. The period from Q4/2022 to Q1/2023 immediately followed the initial EMA endorsement of Pharmacovigilance Risk Assessment Committee (PRAC) recommendations and Q2/2023-Q3/2023 immediately followed the direct healthcare provider communication (DHPC) containing the new safety JAKi recommendations. Results: Between April 1, 2020 and September 23, 2023, 3008 newly initiated therapies for TNFi (1499 [49.8%]), JAKi (1126 [37.4%]), and IL-6Ri (383 [12.7%]) were documented by the treating physicians. JAKi were increasingly used in the first two half-year periods (from 29.7% of these therapies in Q2/2020-Q3/2020 to 46.7% in Q2/2021-Q3/2021; odds ratio [OR] 2.08; p<0.001). The proportion of initiated JAKi therapies decreased significantly after the PRAC recommendations (32.9%; OR vs peak 0.56; p=0.001) and the DHPC letter (26.1%; OR vs peak 0.40; p<0.001). JAKi were more likely to be used as >3rd-line therapy in later time periods. Conclusions: This exploratory study suggests that EMA safety recommendations for JAKi influenced treatment patterns of RA patients who received JAKi in Germany. Additional studies will be needed to confirm these findings.

JAK inhibitors to treat STAT3 gain-of-function: a single-center report and literature review.

Objective: The signal transducer and activator of transcription 3 (STAT3) gain-of-function (GOF) syndrome (STAT3-GOF) is an inborn error of immunity (IEI) characterized by diverse manifestations of immune dysregulation that necessitate systemic immunomodulatory treatment. The blockade of the interleukin-6 receptor and/or the inhibition of the Janus kinases has been commonly employed to treat diverse STAT3-GOF-associated manifestations. However, evidence on long-term treatment outcome, especially in the case of adult patients, is scarce. Methods: Clinical data, including laboratory findings and medical imaging, were collected from all seven patients, diagnosed with STAT3-GOF, who have been treated at the Hannover University School, focusing on those who received a Janus kinase (JAK) inhibitor (JAKi). Previously published cases of STAT3-GOF patients who received a JAKi were evaluated, focusing on reported treatment efficacy with respect to diverse STAT3-GOF-associated manifestations of immune dysregulation and safety. Results: Five out of seven patients diagnosed with STAT3-GOF were treated with a JAKi, each for a different indication. Including these patients, outcomes of JAKi treatment have been reported for a total of 41 patients. Treatment with a JAKi led to improvement of diverse autoimmune, inflammatory, or lymphoproliferative manifestations of STAT3-GOF and a therapeutic benefit could be documented for all except two patients. Considering all reported manifestations of immune dysregulation in each patient, complete remission was achieved in 10/41 (24.4%) treated patients. Conclusions: JAKi treatment improved diverse manifestations of immune dysregulation in the majority of STAT3-GOF patients, representing a promising therapeutic approach. Long-term follow-up data are needed to evaluate possible risks of prolonged treatment with a JAKi.

Janus kinase inhibitors versus tumor necrosis factor inhibitors in rheumatoid arthritis: meta-analytical comparison of efficacy and safety.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder characterized by persistent inflammation leading to progressively worse disability. Janus kinase (JAK) inhibitors and tumor necrosis factor (TNF) inhibitors are pivotal in RA treatment, yet their comparative efficacy remains underexplored. AIM: This study aimed to compare the efficacy and safety of JAK inhibitors and TNF inhibitors in treating RA using data from randomized controlled trials (RCTs). METHODS: A meta-analysis and outcomes analysis were based on results of the Health Assessment Questionnaire Disability Index (HAQ-DI), Clinical Disease Activity Index (CDAI), Visual Analogue Scale (VAS), and Patient Global Assessment Scale (PtGA) and other indices as incidences of venous thromboembolism (VTE) and malignancy. RESULTS: The JAK inhibitors caused a statistically significant improvement in the HAQ-DI score [MD = 0.08, 95% CI (0.03, 0.12), p = 0.0008] compared with the TNF inhibitors. However, no significant difference was observed between the two drug classes in the CDAI score [MD = - 2.03, 95% CI (- 9.27, 5.22), p = 0.58]. JAK inhibitors were associated with an increase in the VAS score [MD = 3.62, 95% CI (0.86, 6.38), p = 0.01], but there was no significant difference in the PtGA score [MD = 1.91, 95% CI (- 3.25, 7.08), p = 0.47]. CONCLUSION: JAK inhibitors demonstrated superior efficacy in improving the functional status and reducing the disease activity in RA patients compared with TNF inhibitors. Both drug classes exhibited comparable safety profiles for VTE and malignancies, though JAK inhibitors had a higher risk for thromboembolism.

Navigating therapeutic challenges in VEXAS syndrome: exploring IL-6 and JAK inhibitors at the forefront.

VEXAS syndrome, an uncommon yet severe autoimmune disorder stemming from a mutation in the UBA1 gene, is the focus of this paper. The overview encompasses its discovery, epidemiological traits, genetic underpinnings, and clinical presentations. Delving into whether distinct genotypes yield varied clinical phenotypes in VEXAS patients, and the consequent adjustment of treatment strategies based on genotypic and clinical profiles necessitates thorough exploration within the clinical realm. Additionally, the current therapeutic landscape and future outlook are examined, with particular attention to the potential therapeutic roles of IL-6 inhibitors and JAK inhibitors, alongside an elucidation of prevailing limitations and avenues for further research. This study contributes essential theoretical groundwork and clinical insights for both diagnosing and managing VEXAS syndrome.

Are Small Molecules Effective in Treating Inflammatory Pouch Disorders Following Ileal Pouch-Anal Anastomosis for Ulcerative Colitis? Here Is Where We Stand.

Ulcerative colitis (UC) management encompasses conventional and advanced treatments, including biological therapy and small molecules. Surgery, particularly in the form of ileal pouch-anal anastomosis (IPAA), is indicated in cases of refractory/severe disease. IPAA can lead to acute complications (e.g., acute pouchitis) as well as late complications, including chronic inflammatory disorders of the pouch. Chronic pouchitis, including the antibiotic-dependent (CADP) and antibiotic-refractory (CARP) forms, represents a significant and current therapeutic challenge due to the substantial need for evidence regarding viable treatment options. Biological therapies have shown promising results, with infliximab, adalimumab, ustekinumab, and vedolizumab demonstrating some efficacy in chronic pouchitis; however, robust randomized clinical trials are only available for vedolizumab. This narrative review focuses on the evidence concerning small molecules in chronic pouchitis, specifically Janus kinase (JAK) inhibitors and sphingosine-1-phosphate receptor (S1P-R) modulators. According to the preliminary studies and reports, Tofacitinib shows a potential effectiveness in CARP. Upadacitinib presents variable outcomes from the case series, necessitating further evaluation. Filgotinib and ozanimod demonstrate anecdotal efficacy. This review underscores the need for high-quality studies and real-world registries to develop robust guidelines for advanced therapies in post-IPAA inflammatory disorders, supported by vigilant clinical monitoring and ongoing education from international IBD specialist societies.

JAK inhibition in Down Syndrome Regression Disorder.

Down Syndrome Regression Disorder (DRSD) is an uncommon but devastating condition affecting primarily adolescents and young adults with Down syndrome (DS). Individuals with DS display a dysregulated immune system associated with hyperactive interferon signaling, which is associated with a high incidence of autoimmune conditions. While the cause of DSRD is unknown, increasing evidence indicates that it may have an immune basis, and some individuals with DSRD have responded to intravenous immunoglobulin therapy. This case series describes three individuals with probable DSRD who received the JAK inhibitor tofacitinib and saw improvement in DSRD symptoms across multiple domains of neurological function.

Response to biological drugs and JAK inhibitors following cyclosporine in patients with atopic dermatitis.

The therapeutic arsenal for atopic dermatitis (AD) has increased in recent years. The use of biologics or Janus kinase inhibitors (JAKi) is advocated following failure or contraindication to cyclosporine (CSA), however, it is not known whether treatment with CSA can impact the response to biologics or JAKi. The aim of this study was to evaluate the effect of previous treatment with CSA on response to biologics or JAKi in patients with AD. This was a retrospective observational study including patients with AD treated for 16 weeks with a biologic or JAKi, who had previously received cyclosporine for at least four weeks. Thirty patients with AD, with a mean age of 25.07±9.91 years, of whom 18 (60%) were women, were included. The mean duration of CSA treatment was 43.39±31.32 weeks. After 16 weeks of biologic or JAKi treatment, 17 (56.7%) patients achieved EASI75. These patients had a higher cumulative dose of CSA (3,6815 vs.76,993.33 mg; p=0.022) and a longer treatment duration (24.5 vs.57.4 weeks; p=0.003). Additionally, a negative correlation was observed between cumulative dose of CSA and EASI or SCORAD at 16 weeks. Previous cumulative dose and longer duration of CSA treatment does not appear to have a negative impact on response to biologics and JAKi in patients with AD.

Therapeutic potential of anticancer activity of nitrogen-containing heterocyclic scaffolds as Janus kinase (JAK) inhibitor: Biological activity, selectivity, and structure-activity relationship.

The JAK-STAT signalling pathway is primarily involved in cytokine signalling and induces various factors namely, erythropoietin, thrombopoietin, interferons, interleukins, and granulocyte colony-stimulating factors. These factors tremendously influenced understanding human health and illness, specifically cancer. Inhibiting the JAK/STAT pathway offers enormous therapeutic promises against cancer. Many JAK inhibitors are now being studied due to their efficacy in various cancer treatments. Further, the Nitrogen-heterocyclic (N-heterocyclic) scaffold has always shown to be a powerful tool for designing and discovering synthetic compounds with diverse pharmacological characteristics. The review focuses on several FDA-approved JAK inhibitors and their systematic categorization. The medicinal chemistry perspective is highlighted and classified review on the basis of N-heterocyclic molecules. Several examples of designing strategies of N-heterocyclic rings including pyrrolo-azepine, purine, 1H-pyrazolo[3,4-d]pyrimidine, 1H-pyrrolo[2,3-b]pyridine, pyrazole, thieno[3,2-d] pyrimidine, and, pyrimidine-based derivatives and their structure-activity relationships (SAR) are discussed. Among the various N-heterocyclic-based JAK inhibitors pyrimidine-containing compound 1 exhibited excellent inhibition activity against JAK2WT and mutated-JAK2V617F with IC50 of 2.01 and 18.84 nM respectively. Amino pyrimidine-containing compound 6 and thiopheno[3,2-d]pyrimidine-containing compound 13 expressed admirable JAK3 inhibition activity with IC50 of 1.7 nM and 1.38 nM respectively. Our review will support the medicinal chemists in refining and directing the development of novel N-heterocyclic-based JAK inhibitors.

Oral Janus Kinase Inhibitors in Pediatric Atopic Dermatitis.

PURPOSE OF REVIEW: To analyze the efficacy and safety of Janus kinase inhibitors (JAKi) in the treatment of pediatric AD. RECENT FINDINGS: Adolescents with moderate and severe atopic dermatitis (AD) need systemic therapies, as stated several recent practice guidelines. (JAKi) have shown their efficacy in the treatment of adult AD, however, there is a lack of information concerning efficacy and safety of their use in pediatric AD. We found that the JAKi's abrocitinib (ABRO), baricitinib (BARI), and upadacitinib (UPA), are all an effective treatment option with a very fast onset of action for adolescents with moderate-to-severe AD. BARI was not effective in children between 2 and 10 years with moderate-to-severe AD. Fortunately, major safety issues with JAKi in adolescents with AD have not been documented in the trials, so far, contrasting with the reports in adults with AD, where these events have very rarely occurred. There are some reports of herpes zoster (HZ) infection in adolescents on JAKi, but it is not a major safety concern. Acne is a relatively common AE with UPA in adolescents; however, it is responsive to standard treatment. This review will help the clinician to choose among the JAKi according to the needs and clinical features of patients with moderate and severe AD. In the following years, with the advent of new biologicals and JAKi, these therapies will fall into place in each phase of the evolution of patients with AD.

A meta-analysis of therapeutic trials of topical ruxolitinib cream for the treatment of vitiligo: therapeutic efficacy, safety, and implications for therapeutic practice.

Vitiligo, an autoimmune condition characterized by depigmented skin patches due to the loss of functional melanocytes, has been linked to dysregulation in the JAK-STAT signaling pathway, particularly in IFN-g signaling. The use of JAK inhibitors, such as ruxolitinib cream, a JAK1 and JAK2 inhibitor, presents a promising approach for vitiligo treatment. This study aims to systematically assess the effectiveness and safety of ruxolitinib cream in patients with vitiligo. We conducted a systematic review and meta-analysis following PRISMA guidelines to evaluate the efficacy and safety of ruxolitinib cream for the treatment of vitiligo. A comprehensive search of PubMed, Google Scholar, and Cochrane Library databases for randomized controlled trials (RCTs). Data selection, screening, extraction, and risk of bias assessment were meticulously performed. Statistical analysis was conducted using Review Manager Software, version 5.4, with significant heterogeneity addressed through appropriate methods. Our meta-analysis included 3 studies with 830 vitiligo patients. Significant improvements were observed in F-VASI, T-VASI, F-BSA, and T-BSA scores, with greater efficacy at 24 weeks compared to 12 weeks [MD -24.17, 95% CI (-31.78 to -16.56), P < 0.00001], [MD -14.12, 95% CI (-20.54 to -7.70); P < 0.0000], [MD -16.25, 95% CI (-22.20 to -10.31), P < 0.00001], [MD -9.19, 95% CI (-13.47 to -4.92); P < 0.00001]. Ruxolitinib showed increased risk ratios for F-VASI75, F-VASI90, and F-VASI50, indicating better outcomes with longer treatment durations [MD 2.9, 95% CI 1.88-4.49; P < 0.00001], [MD 4.66, 95% CI 2.09-10.39; P = 0.0002], [MD 2.53, 95% CI 1.84-3.46; P < 0.00001]. No significant differences were found in mild and moderate adverse events, while severe cases favored ruxolitinib. Placebo had a significant advantage in any adverse events, with no significant difference in drug-related adverse events. Serious adverse events did not significantly differ between groups. The findings strongly support the efficacy of ruxolitinib therapy in improving various parameters over time for treating vitiligo. However, thorough consideration of its safety profile, particularly concerning adverse events and potential side effects, is warranted. Further studies with larger sample sizes are needed to confirm these conclusions.