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

Novel investigational drugs for alopecia areata and future perspectives

INTRODUCTION

Alopecia areata (AA) is an immune-mediated disease that causes non-scarring hair loss. While acute, solitary patches often spontaneously remit, developing secondary patches or failure of the disease to resolve within 6-12 months predicts a poor prognosis, with an increased risk of alopecia totalis or universalis. Chronic AA increases the risk of depression and suicidality and reduces quality of life. Treatment options for chronic or acute diffuse AA were previously limited to corticosteroids and traditional immunomodulators. Two Janus Kinase (JAK) inhibitors are now approved for the treatment of chronic AA.

AREAS COVERED

The results of landmark phase 3 trials for three JAK inhibitors, baricitinib, ritlecitinib, and deuruxolitinib are discussed. Evidence for other JAK inhibitors, biologics, and phosphodiesterase-4 inhibitors are also presented. Therapies currently undergoing clinical trials are listed.

EXPERT OPINION

JAK inhibitors are a safe and efficacious treatment of moderate-to-severe AA. Early intervention, regardless of severity, allows for improved treatment efficacy. It is uncertain how long patients should remain on JAK inhibitors; discontinuation often leads to relapse. A black-box warning for JAK inhibitors was extrapolated from safety data in a rheumatoid arthritis cohort; recent meta-analyses of JAK inhibitors used in dermatology cohorts do not demonstrate the same risk profile.

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.

Immune niches for hair follicle development and homeostasis

The hair follicle is a dynamic mini-organ that has specialized cycles and architectures with diverse cell types to form hairs. Previous studies for several decades have investigated morphogenesis and signaling pathways during embryonic development and adult hair cycles in both mouse and human skin. In particular, hair follicle stem cells and mesenchymal niches received major attention as key players, and their roles and interactions were heavily revealed. Although resident and circulating immune cells affect cellular function and interactions in the skin, research on immune cells has mainly received attention on diseases rather than development or homeostasis. Recently, many studies have suggested the functional roles of diverse immune cells as a niche for hair follicles. Here, we will review recent findings about immune niches for hair follicles and provide insight into mechanisms of hair growth and diseases.

Disease burden, clinical management and unmet treatment need of patients with moderate to severe alopecia areata; consensus statements, insights, and practices from CERTAAE (Central/Eastern EU, Russia, Türkiye AA experts) Delphi panel

Objectives

This study aims to update the understanding of Alopecia Areata (AA) in Poland, Czechia, Russia, and Türkiye, focusing on the disease burden, clinical management, and patient journey. It seeks to establish a consensus on optimal management strategies for AA in these regions.

Methods

A modified 2-round Delphi panel was conveyed with 23 Dermatologists (Russia; 4, Türkiye; 7, Poland; 6, and Czechia; 6). The Delphi questionnaire consisted of 61 statements and 43 questions designed to obtain an overall understanding of the perception and acceptance of available information regarding the care of patients with alopecia areata.

Results

The study revealed that moderate-to-severe AA significantly impacts patients' and their families' QoL, consistent with previous studies. AA was found to cause more substantial impairment when additional lesions appeared in visible areas besides the scalp. Work and productivity impairment were notably higher in adults with moderate-to-severe AA. Diagnostic consensus highlighted the importance of skin biopsies and trichoscopy, while the need for more practical severity scoring systems was emphasized. Current treatments, including topical therapies, corticosteroids, and systemic immune modifiers, were deemed insufficient, highlighting the unmet medical need.

Conclusion

The Delphi study underscores a significant disease burden and unmet medical needs in patients with moderate-to-severe AA. It highlights the necessity of access to novel treatments and further research to develop more effective therapies with a tolerable safety profile. The findings align with global research, emphasizing the psychosocial impact of AA and the need for standardized, effective treatment protocols.

European expert consensus statement on the systemic treatment of alopecia areata

Alopecia areata is an autoimmune form of non-scarring hair loss. It is usually characterized by limited areas of hair loss. However, the disease may progress to complete scalp and body hair loss (alopecia totalis, alopecia universalis). In patients with alopecia areata hair loss significantly impacts the quality of life. Children and adolescents with alopecia areata often experience bullying, including physical aggression. The disease severity evaluation tools used in clinical practice are: the Severity of Alopecia Tool (SALT) score and the Alopecia Areata Scale (AAS). A SALT score equal to or greater than 20 constitutes a commonly accepted indication for systemic therapy in alopecia areata. When using the AAS, moderate to severe alopecia areata should be considered a medical indication for systemic treatment. Currently, the only two EMA-approved medications for alopecia areata are baricitinib (JAK 1/2 inhibitor) for adults and ritlecitinib (JAK 3/TEC inhibitor) for individuals aged 12 and older. Both are EMA-approved for patients with severe alopecia areata. Other systemic medications used off-label in alopecia areata include glucocorticosteroids, cyclosporine, methotrexate and azathioprine. Oral minoxidil is considered an adjuvant therapy with limited data confirming its possible efficacy. This consensus statement is to outline a systemic treatment algorithm for alopecia areata, indications for systemic treatment, available therapeutic options, their efficacy and safety, as well as the duration of the therapy.

The Biology and Genomics of Human Hair Follicles: A Focus on Androgenetic Alopecia

Androgenetic alopecia is a highly prevalent condition mainly affecting men. This complex trait is related to aging and genetics; however, multiple other factors, for example, lifestyle, are also involved. Despite its prevalence, the underlying biology of androgenetic alopecia remains elusive, and thus advances in its treatment have been hindered. Herein, we review the functional anatomy of hair follicles and the cell signaling events that play a role in follicle cycling. We also discuss the pathology of androgenetic alopecia and the known molecular mechanisms underlying this condition. Additionally, we describe studies comparing the transcriptional differences in hair follicles between balding and non-balding scalp regions. Given the genetic contribution, we also discuss the most significant risk variants found to be associated with androgenetic alopecia. A more comprehensive understanding of this pathology may be generated through using multi-omics approaches.

Novel Janus Kinase Inhibitors in the Treatment of Dermatologic Conditions

Janus kinase inhibitors, also known as JAK inhibitors, JAKinibs or JAKi, are a new group of disease-modifying drugs. They work by inhibiting enzymes involved in the transmission of information from receptors located in the cell membrane to the cell interior, specifically to the cell nucleus, thus disrupting the JAK-STAT pathway. This pathway plays a role in key cellular processes such as the immune response and cell growth. This feature is used in the treatment of patients with rheumatological, gastroenterological and hematological diseases. Recently, it has been discovered that JAK-STAT pathway inhibitors also show therapeutic potential against dermatological diseases such as atopic dermatitis, psoriasis, alopecia areata and acquired vitiligo. Studies are underway to use them in the treatment of several other dermatoses. Janus kinase inhibitors represent a promising class of drugs for the treatment of skin diseases refractory to conventional therapy. The purpose of this review is to summarize the latest knowledge on the use of JAKi in dermatological treatment.

Successful treatment of nail lichen planus with tofacitinib: a case report and review of the literature

Nail lichen planus (NLP) is a chronic inflammatory disease of unknown etiology and has been recognized as a nail potentially critical disorder, which can be severe and rapidly worsen with irreversible scarring. Currently, the treatment options are limited based on disease progression. High-potency topical or intralesional corticosteroids are commonly considered first-line therapeutic options; however, these therapies are unsuitable for all patients with NLP, especially those with extensive lesions. As a potential therapeutic target for inflammatory skin diseases, Janus kinase (JAK) inhibitors can suppress both type-1 and type-2 cytokines, thereby reducing the immune response and resultant inflammation. Recent studies have suggested benefit in cutaneous lichen planus and lichen planopilaris with oral JAK inhibitors. Here, we report a case of severe NLP that exhibited a favorable response to tofacitinib treatment. A 41-year-old woman presented to our clinic with a 2-year history of nail dystrophy of all fingers of both hands. The NLP was finally confirmed by histopathology and the above clinical features. After the informed consent signature, tofacitinib monotherapy, 5 mg twice a day, was then begun, and after 6 months, the appearance of her nails had a significant improvement.