Selective inhibition of JAK3 signaling is sufficient to reverse alopecia areata

Small molecule agents against alopecia: Potential targets and related pathways

Alopecia has emerged as a global concern, extending beyond the middle-aged and elderly population and increasingly affecting younger individuals. Despite its growing prevalence, the treatment options and effective drugs for alopecia remain limited due to the incomplete understanding of its underlying mechanisms. Therefore, it is urgent to explore the pathogenesis of alopecia and discover novel and safer therapeutic agents. This review provided an overview of the prevailing clinical disorders of alopecia, and the key pathways and targets involved in hair growth process. Additionally, it discusses FDA-approved drugs and clinical candidates for the treatment of alopecia, and explores small molecule compounds with anti-alopecia potential in the drug discovery phase. These endeavors are expected to provide researchers with valuable scientific insights and practical information for anti-alopecia drug discovery.

Nanostructured lipid carriers promote percutaneous absorption and hair follicle targeting of tofacitinib for treating alopecia areata

Alopecia areata affects over 140 million people worldwide and causes severe psychological distress. The Janus kinase (JAK) inhibitor, tofacitinib, shows significant potential in therapeutic applications for treating alopecia areata; however, the systemic adverse effects of oral administration and low absorption rate at the target site limit its application. Hence, to address this issue, we designed topical formulations of tofacitinib-loaded cationic lipid nanoparticles (TFB-cNLPs) with particle sizes of approximately 200 nm. TFB-cNLPs promoted percutaneous absorption and hair follicle targeting in an ex vivo pig ear model. TFB-cNLP decreased IFN-γ-induced alopecia areata symptoms in an in vitro follicle model by blocking the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway. It also reduced the number of CD8+NKG2D+T cells in a C3H mouse model of alopecia areata in vivo, thereby inhibiting the progression of alopecia areata and reversing hair loss. These findings suggest that TFB-cNLP enhanced hair follicle targeting and has the potential for topical treatment or prevention of alopecia areata.

Comparative efficacy of oral Janus kinase inhibitors and biologics in adult alopecia areata: A systematic review and Bayesian network meta-analysis

Alopecia areata (AA) is an autoimmune disorder that affects the hair follicles, resulting in patchy recurrent hair loss. A large body of evidence has demonstrated the favourable clinical response of the Janus kinase (JAK) inhibitors and biologics, but a lack of comprehensive comparison among these therapies exists in the current literature. This study aimed to compare their efficacy. A systematic review and meta-analysis were performed including randomized trials that report the outcomes of the Severity of Alopecia Tool (SALT)50 and/or the mean change in SALT. These articles were pooled and a network meta-analysis (NAM) was conducted. Based on the surface under the cumulative ranking curve estimates obtained for the mean change in SALT score, baricitinib_4 mg (0.7949656) had the best probability of being the most effective therapy, followed by ritlecitinib_200_50 mg (0.7391906) and ivarmacitinib_4 mg (0.7292594). In contrast, dupilumab, secukinumab, tralokinumab and apremilast were less likely to be effective. Targeting the JAK signalling pathway holds great potential for restoring hair regrowth, albeit the contribution of JAK1, JAK2, JAK3 and TYK2 inhibition to the therapeutic effect on AA is apparently different. Baricitinib_4 mg and ritlecitinib 200_50 mg demonstrated notable efficacy, and both molecules displayed a dose-dependent effect, which is not observed with ivarmacitinib. Further investigations into the specific mechanisms of action of these JAK inhibitors are warranted to elucidate the reasons behind these differences.

Exploring the therapeutic potential of regulatory T cell in rheumatoid arthritis: Insights into subsets, markers, and signaling pathways

Rheumatoid arthritis (RA) is a complex autoimmune inflammatory rheumatic disease characterized by an imbalance between immunological reactivity and immune tolerance. Regulatory T cells (Tregs), which play a crucial role in controlling ongoing autoimmunity and maintaining peripheral tolerance, have shown great potential for the treatment of autoimmune inflammatory rheumatic diseases such as RA. This review aims to provide an updated summary of the latest insights into Treg-targeting techniques in RA. We focus on current therapeutic strategies for targeting Tregs based on discussing their subsets, surface markers, suppressive function, and signaling pathways in RA.

Interleukin-15 is a hair follicle immune privilege guardian

The autoimmunity-promoting cytokine, Interleukin-15 (IL-15), is often claimed to be a key pathogenic cytokine in alopecia areata (AA). Yet, rhIL-15 promotes human hair follicle (HF) growth ex vivo. We have asked whether the expression of IL-15 and its receptor (IL-15R) isoforms is altered in human AA and how IL-15 impacts on human HF immune privilege (HF-IP) in the presence/absence of interferon-γ (IFNγ), the well-documented key AA-pathogenic cytokine, as well as on hair regrowth after experimental AA induction in vivo. Quantitative immunohistomorphometry showed the number of perifollicular IL-15+ T cells in AA skin biopsies to be significantly increased compared to healthy control skin, while IL-15, IL-15Rα, and IL-15Rγ protein expression within the hair bulb were significantly down-regulated in AA HFs. In organ-cultured human scalp HFs, rhIL-15 significantly reduced hair bulb expression of MICA, the key "danger" signal in AA pathogenesis, and increased production of the HF-IP guardian, α-MSH. Crucially, ex vivo, rhIL-15 prevented IFNγ-induced HF-IP collapse, restored a collapsed HF-IP by IL-15Rα-dependent signaling (as documented by IL-15Rα-silencing), and protected AA-preventive immunoinhibitory iNKT10 cells from IFNγ-induced apoptosis. rhIL-15 even promoted hair regrowth after experimental AA induction in human scalp skin xenotransplants on SCID/beige mice in vivo. Our data introduce IL-15 as a novel, functionally important HF-IP guardian whose signaling is constitutively defective in scalp HFs of AA patients. Our data suggest that selective stimulation of intrafollicular IL-15Rα signaling could become a novel therapeutic approach in AA management, while blocking it pharmacologically may hinder both HF-IP restoration and hair re-growth and may thus make HFs more vulnerable to AA relapse.

Modelling Human Hair Follicles-Lessons from Animal Models and Beyond

The hair follicle is a specialized appendage of the skin that is critical for multiple functions, including thermoregulation, immune surveillance, and sebum production. Mammals are born with a fixed number of hair follicles that develop embryonically. Postnatally, these hair follicles undergo regenerative cycles of regression and growth that recapitulate many of the embryonic signaling pathways. Furthermore, hair cycles have a direct impact on skin regeneration in homeostasis, cutaneous wound healing, and disease conditions such as alopecia. Here, we review the current knowledge of hair follicle formation during embryonic development and the post-natal hair cycle, with an emphasis on the molecular signaling pathways underlying these processes. We then discuss efforts to capitalize on the field's understanding of in vivo mechanisms to bioengineer hair follicles or hair-bearing skin in vitro and how such models may be further improved to develop strategies for hair regeneration.

Alternative splicing of CARM1 regulated by LincGET-guided paraspeckles biases the first cell fate in mammalian early embryos

The heterogeneity of CARM1 controls first cell fate bias during early mouse development. However, how this heterogeneity is established is unknown. Here, we show that Carm1 mRNA is of a variety of specific exon-skipping splicing (ESS) isoforms in mouse two-cell to four-cell embryos that contribute to CARM1 heterogeneity. Disruption of paraspeckles promotes the ESS of Carm1 precursor mRNAs (pre-mRNAs). LincGET, but not Neat1, is required for paraspeckle assembly and inhibits the ESS of Carm1 pre-mRNAs in mouse two-cell to four-cell embryos. We further find that LincGET recruits paraspeckles to the Carm1 gene locus through HNRNPU. Interestingly, PCBP1 binds the Carm1 pre-mRNAs and promotes its ESS in the absence of LincGET. Finally, we find that the ESS seen in mouse two-cell to four-cell embryos decreases CARM1 protein levels and leads to trophectoderm fate bias. Our findings demonstrate that alternative splicing of CARM1 has an important role in first cell fate determination.

Discovery of a novel and highly selective JAK3 inhibitor as a potent hair growth promoter

JAK-STAT signalling pathway inhibitors have emerged as promising therapeutic agents for the treatment of hair loss. Among different JAK isoforms, JAK3 has become an ideal target for drug discovery because it only regulates a narrow spectrum of γc cytokines. Here, we report the discovery of MJ04, a novel and highly selective 3-pyrimidinylazaindole based JAK3 inhibitor, as a potential hair growth promoter with an IC50 of 2.03 nM. During in vivo efficacy assays, topical application of MJ04 on DHT-challenged AGA and athymic nude mice resulted in early onset of hair regrowth. Furthermore, MJ04 significantly promoted the growth of human hair follicles under ex-vivo conditions. MJ04 exhibited a reasonably good pharmacokinetic profile and demonstrated a favourable safety profile under in vivo and in vitro conditions. Taken together, we report MJ04 as a highly potent and selective JAK3 inhibitor that exhibits overall properties suitable for topical drug development and advancement to human clinical trials.

Comparative efficacy and safety of JAK inhibitors in the treatment of moderate-to-severe alopecia areata: a systematic review and network meta-analysis

We performed a Bayesian network meta-analysis to indirectly compare the relative efficacy and safety of the latest JAK inhibitors for moderate-to-severe alopecia areata (AA). 13 trials totaling 3,613 patients were included. Two low-dose groups of oral formulations (ritlecitinib 10mg and ivarmacitinib 2mg) and two topical formulations (delgocitinib ointment and ruxolitinib cream) appeared to be relatively ineffective against moderate-to-severe AA. Ranking analysis suggested that brepocitinib 30mg has the best relative effect in reducing the SALT score (sucra = 0.9831), and demonstrated comparable efficacy to deuruxolitinib 12mg (sucra = 0.9245), followed by deuruxolitinib 8mg (sucra = 0.7736). Regarding the SALT50 response, brepocitinib 30mg ranked highest (sucra = 0.9567), followed by ritlecitinib 50mg (sucra = 0.8689) and deuruxolitinib 12mg (sucra = 0.7690). For achieving the SALT75 response, deuruxolitinib 12mg had the highest probability (sucra = 0.9761), followed by deuruxolitinib 8mg (sucra = 0.8678) and brepocitinib 30mg (sucra = 0.8448). Deuruxolitinib 12mg might be the most effective therapy for patients with severe AA (sucra = 0.9395), followed by ritlecitinib 50mg (sucra = 0.8753) and deuruxolitinib 8mg (sucra = 0.8070). Deuruxolitinib 12mg/8mg demonstrated notable efficacy for moderate-to-severe AA, and is expected to be a new treatment option for AA. It was worth noting that deuruxolitinib exhibit a greater likelihood of causing adverse events in comparison to other JAK inhibitors. Ritlecitinib 50mg seemed to exhibit fewer adverse effects in the high-dose groups of oral JAK inhibitors and might be an optimal choice to balance safety and efficacy. The majority of JAK inhibitors exhibited acceptable short-term safety profiles. To enhance the applicability and accuracy of our research, further head-to-head trials with longer follow-up periods are needed. Systematic Review Registration: identifier [CRD42022368012].

Identification of SLC40A1, LCN2, CREB5, and SLC7A11 as ferroptosis-related biomarkers in alopecia areata through machine learning

Alopecia areata (AA) is a common non-scarring hair loss condition driven by the collapse of immune privilege and oxidative stress. The role of ferroptosis, a type of cell death linked to oxidative stress, in AA is yet to be explored, even though it's implicated in various diseases. Using transcriptome data from AA patients and controls from datasets GSE68801 and GSE80342, we aimed to identify AA diagnostic marker genes linked to ferroptosis. We employed Single-sample gene set enrichment analysis (ssGSEA) for immune cell infiltration evaluation. Correlations between ferroptosis-related differentially expressed genes (FRDEGs) and immune cells/functions were identified using Spearman analysis. Feature selection was done through Support vector machine-recursive feature elimination (SVM-RFE) and LASSO regression models. Validation was performed using the GSE80342 dataset, followed by hierarchical internal validation. We also constructed a nomogram to assess the predictive ability of FRDEGs in AA. Furthermore, the expression and distribution of these molecules were confirmed through immunofluorescence. Four genes, namely SLC40A1, LCN2, CREB5, and SLC7A11, were identified as markers for AA. A prediction model based on these genes showed high accuracy (AUC = 0.9052). Immunofluorescence revealed reduced expression of these molecules in AA patients compared to normal controls (NC), with SLC40A1 and CREB5 showing significant differences. Notably, they were primarily localized to the outer root sheath and in proximity to the sebaceous glands. Our study identified several ferroptosis-related genes associated with AA. These findings, emerging from the integration of immune cell infiltration analysis and machine learning, contribute to the evolving understanding of diagnostic and therapeutic strategies in AA. Importantly, this research lays a solid foundation for subsequent studies exploring the intricate relationship between AA and ferroptosis.

Target Occupancy and Functional Inhibition of JAK3 and TEC Family Kinases by Ritlecitinib in Healthy Adults: An Open-Label, Phase 1 Study

Ritlecitinib is a small molecule in clinical development that covalently and irreversibly inhibits Janus kinase 3 (JAK3) and the TEC family of kinases (BTK, BMX, ITK, TXK, and TEC). This phase 1, open-label, parallel-group study assessed target occupancy and functional effects of ritlecitinib on JAK3 and TEC family kinases in healthy participants aged 18-60 years who received 50 or 200 mg single doses of ritlecitinib on day 1. Blood samples to assess ritlecitinib pharmacokinetics, target occupancy, and pharmacodynamics were collected over 48 hours. Target occupancy was assessed using mass spectroscopy. Functional inhibition of JAK3-dependent signaling was measured by the inhibition of the phosphorylation of its downstream target signal transducer and activator of transcription 5 (pSTAT5), following activation by interleukin 15 (IL-15). The functional inhibition of Bruton's tyrosine kinase (BTK)-dependent signaling was measured by the reduction in the upregulation of cluster of differentiation 69 (CD69), an early marker of B-cell activation, following treatment with anti-immunoglobulin D. Eight participants received one 50 mg ritlecitinib dose and 8 participants received one 200 mg dose. Ritlecitinib plasma exposure increased in an approximately dose-proportional manner from 50 to 200 mg. The maximal median JAK3 target occupancy was 72% for 50 mg and 64% for 200 mg. Ritlecitinib 50 mg had >94% maximal target occupancy of all TEC kinases, except BMX (87%), and 200 mg had >97% for all TEC kinases. For BTK and TEC, ritlecitinib maintained high target occupancy throughout a period of 48 hours. Ritlecitinib reduced pSTAT5 levels following IL-15- and BTK-dependent signaling in a dose-dependent manner. These target occupancy and functional assays demonstrate the dual inhibition of the JAK3- and BTK-dependent pathways by ritlecitinib. Further studies are needed to understand the contribution to clinical effects of inhibiting these pathways.

Alopecia areata: What's new in the epidemiology, comorbidities, and pathogenesis?

BACKGROUND

Alopecia areata (AA) is a common, acquired, and nonscarring type of hair loss that affects people of every generation and is intractable in severe and relapsing cases. Patients with AA, especially those with greater scalp involvement, have poor health-related quality-of-life scores.

PURPOSE

Following our previous review article in the April 2017 issue of the Journal of Dermatological Science, we aim to provide a pair of review articles on recent progress in multidisciplinary approaches to AA.

MAIN FINDINGS

We found more than 1800 publications on AA from July 2016 to December 2022.

CONCLUSIONS

In this review, we focused on the latest information on the epidemiology, comorbidities, and pathogenesis of AA.

Inhibition of T-cell activity in alopecia areata: recent developments and new directions

Alopecia areata (AA) is an autoimmune disease that has a complex underlying immunopathogenesis characterized by nonscarring hair loss ranging from small bald patches to complete loss of scalp, face, and/or body hair. Although the etiopathogenesis of AA has not yet been fully characterized, immune privilege collapse at the hair follicle (HF) followed by T-cell receptor recognition of exposed HF autoantigens by autoreactive cytotoxic CD8+ T cells is now understood to play a central role. Few treatment options are available, with the Janus kinase (JAK) 1/2 inhibitor baricitinib (2022) and the selective JAK3/tyrosine kinase expressed in hepatocellular carcinoma (TEC) inhibitor ritlecitinib (2023) being the only US Food and Drug Administration-approved systemic medications thus far for severe AA. Several other treatments are used off-label with limited efficacy and/or suboptimal safety and tolerability. With an increased understanding of the T-cell-mediated autoimmune and inflammatory pathogenesis of AA, additional therapeutic pathways beyond JAK inhibition are currently under investigation for the development of AA therapies. This narrative review presents a detailed overview about the role of T cells and T-cell-signaling pathways in the pathogenesis of AA, with a focus on those pathways targeted by drugs in clinical development for the treatment of AA. A detailed summary of new drugs targeting these pathways with expert commentary on future directions for AA drug development and the importance of targeting multiple T-cell-signaling pathways is also provided in this review.

Nanodrug Delivery Strategies to Signaling Pathways in Alopecia

Over 50% of the global population suffers from hair loss. The mixed results in the treatment of hair loss reveal the limitations of conventional commercial topical drugs. One the one hand, the definite pathogenesis of hair loss is still an enigma. On the other hand, targeted drug carriers ensure the drug therapeutic effect and low side effects. This review highlights the organization and overview of nine crucial signaling pathways associated with hair loss, as well as the development of nanobased topical delivery systems loading the clinical drugs, which will fuel emerging hair loss treatment strategies.

mTOR signaling in hair follicle and hair diseases: recent progress

Mammalian target of rapamycin (mTOR) signaling pathway is a major regulator of cell proliferation and metabolism, playing significant roles in proliferation, apoptosis, inflammation, and illness. More and more evidences showed that the mTOR signaling pathway affects hair follicle circulation and maintains the stability of hair follicle stem cells. mTOR signaling may be a critical cog in Vitamin D receptor (VDR) deficiency-mediated hair follicle damage and degeneration and related alopecia disorders. This review examines the function of mTOR signaling in hair follicles and hair diseases, and talks about the underlying molecular mechanisms that mTOR signaling regulates.

Current application status and structure-activity relationship of selective and non-selective JAK inhibitors in diseases

JAK kinase includes four family members: JAK1, JAK2, JAK3, and TYK2. It forms the JAK-STAT pathway with signal transmitters and activators of subscription (STAT). This pathway is one of the main mechanisms by which many cytokine receptors transduce intracellular signals, it is associated with the occurrence of various immune, inflammatory, and tumor diseases. JAK inhibitors block the signal transduction of the JAK-STAT pathway by targeting JAK kinase. Based on whether they target multiple subtypes of JAK kinase, JAK inhibitors are categorized into pan-JAK inhibitors and selective JAK inhibitors. Compared with pan JAK inhibitors, selective JAK inhibitors are associated with a specific member, thus more targeted in therapy, with improved efficacy and reduced side effects. Currently, a number of JAK inhibitors have been approval for disease treatment. This review summarized the current application status of JAK inhibitors that have been marketed, advances of JAK inhibitors currently in phase Ш clinical trials, and the structure-activity relationship of them, with an intention to provide references for the development of novel JAK inhibitors.

Effect of Janus Kinase 3 Inhibitor on Sebaceous Gland Regeneration during Skin Wound Healing

BACKGROUND

Janus kinase (Jak) 3 has recently been shown as a beneficial target for the treatment of chronic inflammatory diseases, such as psoriasis and alopecia areata. The role of Jak3 in tissue repair and remodeling is emerging.

OBJECTIVE

This study aimed to investigate the role of Jak3 signaling in the remodeling of the sebaceous gland (SG) during skin wound repair, and the development of in vitro SGs.

METHODS

Mouse skin tissue (ICR mouse) was obtained from the recovered skin eight days after a 4 mm biopsy punch wound. To observe the role of Jak3, the selective inhibitors WHI-p131 and PF06651600 was administered. Formation of in vitro SG was examined using primary sebocyte cultures obtained postnatally from 3-day-old mice.

RESULTS

The data showed that SGs showed highly positive signals with anti-isolectin B4, which also used for detection of angiogenetic vessels and the basal epidermis. Isolectin B4 could be a good indicator of SGs. The Jak3 inhibitors significantly reduced the area and volume of SG remodeling with reduced expression of p-Jak3. In addition, the area of cultured intact SG in vitro was significantly decreased in a concentration-dependent manner by Jak3 inhibition.

CONCLUSION

These data showed that Jak3 signaling is a potent regulator to develop SGs. Jak3 inhibition did not decrease the number of sebocytes in SGs but decreased the area and volume of SG remodeling. Therefore, Jak3 inhibition may be a potential target for the treatment of SG hyperplasia and associated skin diseases.

Functional interrogation of lymphocyte subsets in alopecia areata using single-cell RNA sequencing

Alopecia areata (AA) is among the most prevalent autoimmune diseases, but the development of innovative therapeutic strategies has lagged due to an incomplete understanding of the immunological underpinnings of disease. Here, we performed single-cell RNA sequencing (scRNAseq) of skin-infiltrating immune cells from the graft-induced C3H/HeJ mouse model of AA, coupled with antibody-based depletion to interrogate the functional role of specific cell types in AA in vivo. Since AA is predominantly T cell-mediated, we focused on dissecting lymphocyte function in AA. Both our scRNAseq and functional studies established CD8+ T cells as the primary disease-driving cell type in AA. Only the depletion of CD8+ T cells, but not CD4+ T cells, NK, B, or γδ T cells, was sufficient to prevent and reverse AA. Selective depletion of regulatory T cells (Treg) showed that Treg are protective against AA in C3H/HeJ mice, suggesting that failure of Treg-mediated immunosuppression is not a major disease mechanism in AA. Focused analyses of CD8+ T cells revealed five subsets, whose heterogeneity is defined by an "effectorness gradient" of interrelated transcriptional states that culminate in increased effector function and tissue residency. scRNAseq of human AA skin showed that CD8+ T cells in human AA follow a similar trajectory, underscoring that shared mechanisms drive disease in both murine and human AA. Our study represents a comprehensive, systematic interrogation of lymphocyte heterogeneity in AA and uncovers a novel framework for AA-associated CD8+ T cells with implications for the design of future therapeutics.

Markers of Venous Thromboembolism Risk in Patients with Alopecia Areata: Is There Anything to Worry about?

BACKGROUND

Numerous studies have indicated that alopecia areata is associated with a chronic systemic inflammation, which is considered as a risk factor for venous thromboembolism. The aim of the study was to evaluate the following markers of venous thromboembolism risk: soluble fibrin monomer complex (SFMC), thrombin-antithrombin complex (TATC), and prothrombin fragment 1 + 2 (F1 + 2) in patients with alopecia areata and compare them with healthy controls.

METHODS

In total, 51 patients with alopecia areata [35 women and 16 men; mean age: 38 (19-54) years] and 26 controls [18 women and 8 men; mean age: 37 (29-51) years] were enrolled in the study. The serum concentrations of thromboembolism markers were measured using an enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

An increased level of SFMC was detected in patients with alopecia areata compared with the controls [25.66 (20-34.86) versus 21.46 (15.38-29.48) µg/ml; p < 0.05)]. In addition, a higher level of F1 + 2 was observed in patients with alopecia areata in comparison with the control group [70150 (43720-86070) versus 38620 (31550-58840) pg/ml; p < 0.001]. No significant correlation was detected among SFMC or F1 + 2 and the Severity of Alopecia Tool (SALT) score, disease duration, or the number of the hair loss episodes.

CONCLUSION

Alopecia areata may be associated with an increased risk of venous thromboembolism. Regular screening and preventive management of venous thromboembolism may be beneficial in patients with alopecia areata, especially before and during systemic Janus kinase (JAK) inhibitors or glucocorticoid therapy.

Which is the Ideal JAK Inhibitor for Alopecia Areata - Baricitinib, Tofacitinib, Ritlecitinib or Ifidancitinib - Revisiting the Immunomechanisms of the JAK Pathway

Alopecia areata (AA) is an immune-mediated condition, clinically manifesting as non-cicatricial patches of alopecia. It is often a self-limiting condition; however, regrowth of hair can take a long period of time, resulting in significant psychological comorbidity. With the recent advances in pathomechanisms of AA, the therapeutic approach to the condition has become more specific, and targeted therapy with small molecules is probably the ideal intervention. Many therapies exist for AA, but none of the systemic agents were approved, until recently, when baricitinib (Janus kinase (JAK1 and JAK2 inhibitor) gained FDA approval for the treatment of adult patients with severe AA. JAK inhibitors (JAKibs) target the γc cytokine and interferon-gamma (IFN-γ) signaling pathway, which is critical to the immunopathogenesis of AA and thus can reverse the hair loss in AA. Although JAKibs are emerging as a promising treatment modality for AA, the ideal JAKib is not yet settled, as there is scant data on H-2-H (head-to-head) comparisons of JAK inhibitors in AA. Moreover, the response achieved with JAKibs is not sustained after treatment discontinuation, with many studies showing a high recurrence rate with tofacitinib and ruxolitinib post-treatment. Also, recent studies have hypothesized that JAK2, with its ubiquitous expression, can cause adverse effects, unlike JAK1, which is associated with multiple major cytokine receptor families and JAK3, which is exclusively associated with the γc cytokine receptor. Thus, JAK3ibs may be associated with a better side effect profile and, in conjunction with their specificity, may replace other JAKibs as the treatment of choice for AA. We herein discuss the role of the JAK/STAT (signal transducer and activator of transcription) pathway in AA, the intricacies of various JAKibs in the management of AA, and emphasize the need for studies on tissue JAK and cytokine expression before arriving at the ideal JAKibs for AA.

Janus Kinase Inhibitors for Alopecia Areata: A Systematic Review and Meta-Analysis

Importance

Alopecia areata (AA) is a common chronic tissue-specific autoimmune disease. Several studies have reported outcomes of Janus kinase (JAK) inhibitors for treating AA, but limited evidence has emerged.

Objective

To evaluate the effectiveness and safety associated with JAK inhibitors for AA.

Data Sources

MEDLINE, Embase, and CENTRAL (Cochrane Central Register of Controlled Trials) were searched from inception until August 2022.

Study Selection

Only randomized clinical trials (RCTs) were included. Pairs of reviewers independently and in duplicate selected the studies.

Data Extraction and Synthesis

Hartung-Knapp-Sidik-Jonkman random-effects models were used for meta-analysis. Certainty of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. This study is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.

Main Outcomes and Measures

The primary outcomes of interest were (1) proportion of patients who achieved 30%, 50%, and 90% improvement in Severity of Alopecia Tool (SALT) score from baseline, (2) change from baseline SALT score, and (3) treatment-related adverse event (AE).

Results

Seven RCTs with 1710 patients (1083 females [63.3%]; mean [SD] age range, 36.3 [10.4] to 69.7 [16.2] years) were eligible and included in the study. JAK inhibitors were associated with more patients achieving 50% improvement (odds ratio [OR], 5.28 [95% CI, 1.69-16.46]; GRADE assessment: low certainty) and 90% improvement (OR, 8.15 [95% CI, 4.42-15.03]; GRADE assessment: low certainty) in SALT score from baseline compared with placebo. JAK inhibitors were associated with more lowered SALT scores from the baseline compared with placebo (mean difference [MD], -34.52 [95% CI, -37.80 to -31.24]; GRADE assessment: moderate certainty), and JAK inhibitors were not associated with more treatment-related AEs (relative risk [RR], 1.25 [95% CI, 1.00-1.57]; GRADE assessment: high certainty) compared with placebo. High certainty of evidence showed that JAK inhibitors may not be associated with more severe AEs compared with placebo (RR, 0.77; 95% CI, 0.41-1.43). The subgroup analysis showed that oral JAK inhibitors were more efficient than placebo (change from baseline SALT scores: MD, -36.80; 95% CI, -39.57 to -34.02), and no difference was found between external JAK inhibitors and placebo (change from baseline SALT scores: MD, -0.40; 95% CI, -11.30 to 10.50).

Conclusions and Relevance

Results of this systematic review and meta-analysis suggest that JAK inhibitors, compared with placebo, were associated with hair regrowth and that the outcome of oral JAK inhibitors was better than the external route of administration. Although the safety and tolerability of JAK inhibitors were acceptable, longer RCTs are needed to further assess the effectiveness and safety of these treatments for AA.

Discovery of C-5 Pyrazole-Substituted Pyrrolopyridine Derivatives as Potent and Selective Inhibitors for Janus Kinase 1

Developing selective inhibitors for Janus kinase 1 (JAK1) is a significant focus for improving the efficacy and alleviating the adverse effects in treating immune-inflammatory diseases. Herein, we report the discovery of a series of C-5 pyrazole-modified pyrrolopyrimidine derivatives as JAK1-selective inhibitors. The potential hydrogen bond between the pyrazole group and E966 in JAK1 is the key point that enhances JAK1 selectivity. These compounds exhibit 10- to 20-fold JAK1 selectivity over JAK2 in enzyme assays. Compound 12b also exhibits excellent JAK1 selectivity in Ba/F3-TEL-JAK cellular assays. Metabolism studies and the results of the hair growth model in mice indicate that compound 12b may be a viable lead compound for the development of highly JAK1-selective inhibitors for immune and inflammatory diseases.

Selective Delivery of Tofacitinib Citrate to Hair Follicles Using Lipid-Coated Calcium Carbonate Nanocarrier Controls Chemotherapy-Induced Alopecia Areata

Chemotherapy-induced alopecia (CIA) is one of the common side effects in cancer treatment. The psychological distress caused by hair loss may cause patients to discontinue chemotherapy, affecting the efficacy of the treatment. The JAK inhibitor, Tofacitinib citrate (TFC), showed huge potential in therapeutic applications for treating baldness, but the systemic adverse effects of oral administration and low absorption rate at the target site limited its widespread application in alopecia. To overcome these problems, we designed phospholipid-calcium carbonate hybrid nanoparticles (PL/ACC NPs) for a topical application to target deliver TFC. The results proved that PL/ACC-TFC NPs showed excellent pH sensitivity and transdermal penetration in vitro. PL/ACC NPs offered an efficient follicular targeting approach to deliver TFC in a Cyclophosphamide (CYP)-induced alopecia areata mouse model. Compared to the topical application of TFC solution, PL/ACC-TFC NPs significantly inhibited apoptosis of mouse hair follicles and accelerated hair growth. These findings support that PL/ACC-TFC NPs has the potential for topical application in preventing and mitigating CYP-induced Alopecia areata.

Efficacy and safety of ritlecitinib in adults and adolescents with alopecia areata: a randomised, double-blind, multicentre, phase 2b-3 trial

BACKGROUND

Alopecia areata is characterised by non-scarring loss of scalp, face, or body hair. We investigated the efficacy and safety of ritlecitinib, an oral, selective dual JAK3/TEC family kinase inhibitor, in patients with alopecia areata.

METHODS

In this randomised, double-blind, multicentre, phase 2b-3 trial done at 118 sites in 18 countries, patients aged 12 years and older with alopecia areata and at least 50% scalp hair loss were randomly assigned to oral ritlecitinib or placebo once-daily for 24 weeks, with or without a 4-week loading dose (50 mg, 30 mg, 10 mg, 200 mg loading dose followed by 50 mg, or 200 mg loading dose followed by 30 mg), followed by a 24-week extension period during which ritlecitinib groups continued their assigned doses and patients initially assigned to placebo switched to ritlecitinib 50 mg or 200 mg loading dose followed by 50 mg. Randomisation was done by use of an interactive response system and was stratified by baseline disease severity and age. The sponsor, patients, and investigators were masked to treatment, and all patients received the same number of tablets to maintain masking. The primary endpoint was Severity of Alopecia Tool (SALT) score 20 or less at week 24. The primary endpoint was assessed in all assigned patients, regardless of whether they received treatment. This study was registered with ClinicalTrials.gov, NCT03732807.

FINDINGS

Between Dec 3, 2018, and June 24, 2021, 1097 patients were screened and 718 were randomly assigned to receive ritlecitinib 200 mg + 50 mg (n=132), 200 mg + 30 mg (n=130), 50 mg (n=130), 30 mg (n=132), 10 mg (n=63), placebo to 50 mg (n=66), or placebo to 200 mg + 50 mg (n=65). 446 (62%) of 718 patients were female and 272 (38%) were male. 488 (68%) were White, 186 (26%) were Asian, and 27 (4%) were Black or African American. Of 718 patients randomly assigned, 104 patients discontinued treatment (34 withdrew, 19 adverse events [AEs], 12 physician decision, 12 lack of efficacy, 13 lost to follow up, five rolled over to long-term study transfer, four pregnancies, two protocol deviations, one declined to attend follow-up due to COVID-19, one attended last visit very late due to COVID-19, and one non-compliance). At week 24, 38 (31%) of 124 patients in the ritlecitinib 200 mg + 50 mg group, 27 (22%) of 121 patients in the 200 mg + 30 mg group, 29 (23%) of 124 patients in the 50 mg group, 17 (14%) of 119 patients in the 30 mg group, and two (2%) of 130 patients in the placebo group had a response based on SALT score 20 or less. The difference in response rate based on SALT score 20 or less between the placebo and the ritlecitinib 200 mg + 50 mg group was 29·1% (95% CI 21·2-37·9; p<0·0001), 20·8% (13·7-29·2; p<0·0001) for the 200 mg + 30 mg group, 21·9% (14·7-30·2; p<0·0001) for the 50 mg group, and 12·8% (6·7-20·4; p=0·0002) for the 30 mg group. Up to week 48 and including the follow-up period, AEs had been reported in 108 (82%) of 131 patients in the ritlecitinib 200 mg + 50 mg group, 105 (81%) of 129 patients in the 200 mg + 30 mg group, 110 (85%) of 130 patients in the 50 mg group, 106 (80%) of 132 patients in the 30 mg group, 47 (76%) of 62 patients in the 10 mg group, 54 (83%) of 65 patients placebo to ritlecitinib 200 mg + 50 mg in the extension period, and 57 (86%) of 66 patients in the placebo to 50 mg group. The incidence of each AE was similar between groups, and there were no deaths.

INTERPRETATION

Ritlecitinib was effective and well tolerated in patients aged 12 years and older with alopecia areata. Ritlecitinib might be a suitable treatment option for alopecia areata in patients who are candidates for systemic therapy.

FUNDING

Pfizer.

JAK inhibitors in dermatology: the road travelled and path ahead, a narrative review

INTRODUCTION

Numerous cutaneous dermatoses mediated by cytokines depend on the JAK STAT pathway for intracellular signaling. JAK inhibitors form a useful therapeutic approach in treating these conditions. The literature on effectiveness of JAK inhibitors in treatment of alopecia areata, vitiligo, atopic dermatitis, psoriasis and several other inflammatory and autoimmune diseases is growing, although very few conditions have sufficiently well performed studies to their credit and barring a few indications, their use in rest remains empirical as yet.

AREAS COVERED

A search of the PubMed database was made using the keywords Janus kinase inhibitors OR JAK inhibitors AND dermatology with the time duration limited to the last 5 years. Here, we review the JAK STAT pathway and the various conditions in which JAK inhibitors are currently used in dermatology and other conditions their use is being explored in.

EXPERT OPINION

The pathology of a large number of dermatological disorders is mediated via inflammatory cytokines which signal via the JAK STAT pathway. JAKinibs have shown great promise in treating cutaneous disorders refractory to conventional therapy. Their current clinical use in dermatology is based on robust evidence (for some), and anecdotal evidence for most other dermatoses.

Efficacy of PF-06651600 in alleviating the pro-inflammatory capacity of CD4+ T cells in rheumatoid arthritis patients

INTRODUCTION

PF-06651600 is a highly specific inhibitor of Janus-activated kinase 3 and the Tec family of kinases. Regarding its dual function in the inhibition of both γc cytokine receptors and T cell receptor signaling, the present study aimed at evaluating the impact of PF-06651600 on the status of T-helper cells (Th) as the central game players in the pathogenesis of rheumatoid arthritis (RA).

METHOD

TCD4⁺ cells were isolated from 34 RA patients and 15 healthy control individuals and were evaluated after treatment with PF-06651600.

RESULTS

RA patients had higher percentages of TCD4⁺ cells, CD4⁺ PD-1⁺ cells, and CD4⁺ PD-1⁺ TIGIT⁺ cells compared to a healthy control group and the TCD4⁺ cells of these patients showed higher interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-17 secretion along with higher messenger RNA (mRNA) expressions of T-bet. The percentage of CD4⁺ PD-1⁺ TIGIT⁺ cells showed a reverse correlation with the Disease Activity Score of 28 joints of the RA patients. PF-06651600 caused a significant decrease in the mRNA expressions of T-bet and RAR-related orphan receptor γt and the secretion of interferon (IFN)-γ and TNF-α in TCD4⁺ cells of RA patients. On the other hand, the population of CD4⁺ PD-1⁺ TIGIT⁺ cells was expanded under the influence of PF-06651600. This treatment also reduced the proliferation of TCD4⁺ cells.

CONCLUSION

PF-06651600 demonstrated a potential to modulate the activity of TCD4⁺ cells in RA patients and to reduce the commitment of Th cells to the pathogenic Th1 and Th17 subsets. Further, it caused TCD4⁺ cells to gain an exhausted phenotype which is associated with better prognosis in RA patients.

Real-world experience and long-term evaluation of tofacitinib in refractory alopecia areata: A prospective, open-label, single-center study in Asian Arab population

Tofacitinib is a pan-janus kinase inhibitor (JAK) which has been tested off-label in alopecia areata (AA) with promising results. However, evidence of tofacitinib in real-life setting is still poor. We evaluated long-term efficacy and safety of tofacitinib for refractory AA. This is a prospective, open-label, observational, single-center cohort study conducted between January 2018 and December 2020. Primary end-point was the percent change in Severity of Alopecia Tool (SALT) at the basal visit and at the most recent follow-up visit. Three categories of treatment response were analyzed. Data on 47 participants of Arab-Asian heritage were analyzed. A complete and partial regrowth was observed in 18 patients (41.86%) and 11 patients (25.58%), respectively. In 12 patients (27.9%), no response was obtained. Most of the non-responders belonged to the alopecia universalis group (66.67%). No statistical differences were observed in rates of regrowth between pediatric and adult individuals (p = 0.52), nor between women and men. Significant differences in the average duration of tofacitinib treatment were obtained among the three categories of regrowth (p < 0.003), notably duration of AA did not impact the clinical regrowth (p = 0.62). To the best of our knowledge, this is the first prospective, observational, long-term study using tofacitinib in refractory AA. Rates of regrowth and side effects are analogous to previous works. Length of tofacinitib therapy should last for 12 months before considering any discontinuation or change, since early cessation can lead to treatment failures or incomplete regrowth. Maintenance therapy after complete regrowth has demonstrated to be safe and effective to prevent recurrences of hair loss.

Ex Vivo Treatment with Allogenic Mesenchymal Stem Cells of a Healthy Donor on Peripheral Blood Mononuclear Cells of Patients with Severe Alopecia Areata: Targeting Dysregulated T Cells and the Acquisition of Immunotolerance

Alopecia areata (AA) is an autoimmune condition related to the collapse of the immune privilege of hair follicles. Certain AA populations present severe clinical manifestations, such as total scalp hair or body hair loss and a treatment refractory property. The aim of this study was to assess the effects of allogenic human mesenchymal stem cells (hMSCs) from healthy donors on the peripheral blood mononuclear cells (PBMCs) of severe AA patients, with a focus on the change in the cell fraction of Th1, Th17, and Treg cells and immunomodulatory functions. PBMCs of 10 AA patients and eight healthy controls were collected. Levels of Th17, Th1, and Treg subsets were determined via flow cytometry at baseline, activation status, and after co-culturing with hMSCs. All participants were severe AA patients with SALT > 50 and with a long disease duration. While the baseline Th1 and Treg levels of AA patients were comparable to those of healthy controls, their Th17 levels were significantly lower than those of the controls. When stimulated, the levels of CD4+IFN-γ+ T cells of the AA patients rose sharply compared to the baseline, which was not the case in those of healthy controls. The cell fraction of CD4+Foxp3+ regulatory T cells also abruptly increased in AA patients only. Co-culturing with allogenic hMSCs in activated AA PBMCs slightly suppressed the activation levels of CD4+INF-γ+ T cells, whereas it significantly induced the differentiation of CD4+Foxp3+ regulatory T cells. However, these changes were not prominent in the PBMCs of health controls. To examine the pathomechanisms, PBMCs of healthy donors were treated with IFN-γ to induce AA-like environment and then treated with allogenic grants and compared with ruxolitinib as a positive treatment control. hMSC treatment was shown to significantly inhibit the mRNA levels of proinflammatory cytokines, such as IFN-γ, TNF-α, IL-1α, IL-2R, IL-15, and IL-18, and chemokines, such as CCR7 and CCR10, in IFN-treated PBMCs. Interestingly, hMSCs suppressed the activation of JAK/STAT signaling by IFN in PBMCs with an effect that was comparable to that of ruxolitinib. Furthermore, the hMSC treatment showed stronger efficacy in inducing Foxp3, IL-10, and TGF-β mRNA transcription than ruxolitinib in IFN-treated PBMCs. This study suggests that allogenic hMSC treatments have therapeutic potential to induce immune tolerance and anti-inflammatory effects in severe AA patients.

Induction of T cell exhaustion by JAK1/3 inhibition in the treatment of alopecia areata

Alopecia areata (AA) is an autoimmune disease caused by T cell-mediated destruction of the hair follicle (HF). Therefore, approaches that effectively disrupt pathogenic T cell responses are predicted to have therapeutic benefit for AA treatment. T cells rely on the duality of T cell receptor (TCR) and gamma chain (γc) cytokine signaling for their development, activation, and peripheral homeostasis. Ifidancitinib is a potent and selective next-generation JAK1/3 inhibitor predicted to disrupt γc cytokine signaling. We found that Ifidancitinib robustly induced hair regrowth in AA-affected C3H/HeJ mice when fed with Ifidancitinib in chow diets. Skin taken from Ifidancitinib-treated mice showed significantly decreased AA-associated inflammation. CD44⁺CD62L^- CD8⁺ T effector/memory cells, which are associated with the pathogenesis of AA, were significantly decreased in the peripheral lymphoid organs in Ifidancitinib-treated mice. We observed high expression of co-inhibitory receptors PD-1 on effector/memory CD8⁺ T cells, together with decreased IFN-γ production in Ifidancitinib-treated mice. Furthermore, we found that γc cytokines regulated T cell exhaustion. Taken together, our data indicate that selective induction of T cell exhaustion using a JAK inhibitor may offer a mechanistic explanation for the success of this treatment strategy in the reversal of autoimmune diseases such as AA.

The efficacy and safety of JAK inhibitors for alopecia areata: A systematic review and meta-analysis of prospective studies

Background: Due to the lack of comprehensive evidence based on prospective studies, the efficacy and safety of Janus Kinase (JAK) inhibitors (including tofacitinib, ruxolitinib, baricitinib, ritlecitinib and brepocitinib) for alopecia areata (AA) are yet to be proved.

Methods: The systematic review and meta-analysis was performed pursuant to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline and registered on PROSPERO (CRD42022303007).

Results: Fourteen prospective studies (5 RCTs and 9 non-RCTs), enrolling a total of 1845 patients with AA, were included for quantitative analysis. In RCTs, oral JAK inhibitors resulted in higher good response rate compared with control (RR: 6.86, 95% CI: 2.91–16.16); topical JAK inhibitors did not show any difference compared with control (RR: 1.00, 95% CI: 0.31–3.18). In non-RCTs, the pooled rate of good response to oral, topical and sublingual JAK inhibitors were 63% (95% CI: 44%–80%), 28% (95% CI: 1%–72%) and 11% (95% CI: 1%–29%), respectively. The pooled recurrence rate in patients treated with JAK inhibitors was 54% (95% CI: 39%–69%), mainly due to the withdrawal of JAK inhibitors. In RCTs, no difference was found in the risk of experiencing most kind of adverse events; in non-RCTs, the reported adverse events with high incidence rate were mostly mild and manageable.

Conclusion: JAK inhibitors are efficacious and generally well-tolerated in treating AA with oral administration, whereas topical or sublingual administration lacks efficacy. Subgroup analyses indicate that baricitinib, ritlecitinib and brepocitinib seem to have equal efficacy for AA in RCTs; ruxolitinib (vs. tofacitinib) and AA (vs. AT/AU) are associated with better efficacy outcomes in non-RCT. Due to the high recurrence rate after withdrawal of JAK inhibitors, continuous treatment should be considered to maintain efficacy.

Systematic Review Registration: PROSPERO: CRD 42022303007

Translational impact of omics studies in alopecia areata: recent advances and future perspectives

INTRODUCTION

Alopecia areata (AA) is a non-scarring, hair loss disorder and a common autoimmune-mediated disease with an estimated lifetime risk of about 2%. To date, the treatment of AA is mainly based on suppression or stimulation of the immune response. Genomics and transcriptomics studies generated important insights into the underlying pathophysiology, enabled discovery of molecular disease signatures, which were used in some of the recent clinical trials to monitor drug response and substantiated the consideration of new therapeutic modalities for the treatment of AA such as abatacept, dupilumab, ustekinumab and Janus Kinase (JAK) inhibitors.

AREAS COVERED

In this review, genomics and transcriptomics studies in AA are discussed in detail with particular emphasis on their past and prospective translational impacts. Microbiome studies are also briefly introduced.

EXPERT OPINION

The generation of large datasets using the new high-throughput technologies has revolutionized medical research and AA has also benefited from the wave of omics studies. However, the limitations associated with JAK inhibitors and clinical heterogeneity in AA patients underscore the necessity for continuing omics research in AA for discovery of novel therapeutic modalities and development of clinical tools for precision medicine.

Evaluating the Therapeutic Potential of Ritlecitinib for the Treatment of Alopecia Areata

Alopecia areata (AA) is an autoimmune condition that causes patchy hair loss, affecting up to 147 million people globally. Currently, there are no treatments approved by US Food and Drug Administration (FDA) specific for AA, and there are few effective therapeutic options for widespread and persistent illness. There is an ongoing need for a treatment that demonstrates a good clinical response with a benefit-risk ratio that is suitable for long-term use, especially for patients with chronic, extensive disease. Several clinical trials and case studies that have assessed Janus kinase inhibitors have had encouraging results. Ritlecitinib, a selective JAK3/TEC kinase inhibitor has been demonstrated to inhibit the action of signaling molecules and immune cells that are responsible for hair loss in people with alopecia areata. Furthermore, several clinical trials are investigating the utility of ritlecitinib in patients with vitiligo, rheumatoid arthritis, Crohn’s disease, and ulcerative colitis. Advantages of using ritlecitinib when compared with other non-selective JAK inhibitors include avoiding JAK1/JAK2 inhibition’s clinical repercussions, which include pharmacodynamic effects such as increased cholesterol and liver enzymes, and those related to JAK2 inhibition (thrombocytopenia, anemia). Treatment with Ritlecitinib 50 mg and 30 mg daily for 24 weeks has been shown to induce hair regrowth with a significant proportion of patients reaching SALT 20 (≤20% scalp hair loss) after six months of therapy compared to placebo. Additional research is needed for long-term effects.

Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these “druggable” inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

Application of Baricitinib in Dermatology

There are four JAK subtypes: JAK1, JAK2, JAK3, and tyrosine kinase 2 (TYK2). Small molecule Janus tyrosine kinase (JAK) inhibitors can inhibit a variety of pro-inflammatory cytokines. Baricitinib is the first generation of JAK1/2 inhibitor targeting the ATPase of JAK, which blocks the intracellular transmission of cytokines through JAK-STATs. Thus far, it has been approved for the treatment of rheumatoid arthritis (RA); however, an increasing number of studies have suggested that baricitinib can be used to treat dermatological diseases, such as atopic dermatitis (AD), psoriasis, vitiligo, and alopecia areata. Baricitinib can be a new choice for the treatment of dermatological diseases, which cannot be treated with conventional drugs. We reviewed the application, efficacy, side effects, precautions, limitations and prospect of baricitinib in atopic dermatitis, psoriasis, vitiligo and alopecia areata (AA) in recent 5 years including clinical trials and case reports. Among them, the application in the field of alopecia areata is the most encouraging, and we reviewed the mechanism in detail.

T-cell subsets in the skin and their role in inflammatory skin disorders

T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T-cell subsets with specific functions. These subsets are classified based on their T-cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T-cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T-cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T-cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders.

JAK3 inhibitors for the treatment of inflammatory and autoimmune diseases: a patent review (2016-present)

INTRODUCTION

Up to now, a total of eight Janus kinase (JAK) inhibitors have been approved for the treatment of autoimmune and myeloproliferative disease. The JAK family belongs to the non-receptor tyrosine kinase family, consisting of JAK1, JAK2, JAK3, and tyrosine kinase 2. Among these four subtypes, only JAK3 is mainly expressed in hematopoietic tissue cells and is exclusively associated with the cytokines shared in the common gamma chain receptor subunit. Due to its specific tissue distribution and functional characteristics that distinguish it from the other JAKs family subtypes, JAK3 is a promising target for the treatment of autoimmune disease.

AREAS COVERED

This study aimed to provide a comprehensive review of the available patent literature on JAK-family inhibitors published from 2016 to the present. In addition, an overview of the clinical activities of selective JAK3 inhibitors in recent years was provided.

EXPERT OPINION

To date, no selective JAK3 inhibitors have been approved for use in clinics. Over the last five years, an increasing number of studies on JAK3 inhibitors, particularly ritlecitinib by Pfizer, have demonstrated their promising therapeutic potential. In this review, recent studies reported that selective JAK3 inhibitors may offer valid, interesting, and promising therapeutic potential in inflammatory and autoimmune diseases.

Regulatory network analysis defines unique drug mechanisms of action and facilitates patient-drug matching in alopecia areata clinical trials

Not all therapeutics are created equal in regards to individual patients. The problem of identifying which compound will work best with which patient is a significant burden across all disease contexts. In the context of autoimmune diseases such as alopecia areata, several formulations of JAK/STAT inhibitors have demonstrated efficacy in clinical trials. All of these compounds demonstrate different rates of response, and here we observed that this coincided with different molecular effects on patients undergoing treatment. Using these data, we have developed a computational model that is capable of predicting which patient-drug pairs have the highest likelihood of response. We achieved this by integrating inferred mechanism of action data and gene regulatory networks derived from an independent patient cohort with baseline patient data prior to beginning treatment.