Ritlecitinib in Alopecia Areata: A 24‐Week Real‐World Experience Contrasting <scp>JAK</scp> Inhibitor‐Naïve and <scp>JAK</scp> Inhibitor‐Experienced Patients

Alopecia areata (AA) is a chronic autoimmune disorder characterized by refractory non-scarring hair loss. Although baricitinib revolutionized AA management, some severe cases remain refractory. Ritlecitinib, an oral selective dual JAK3 and tyrosine kinase expressed in hepatocellular carcinoma (TEC) family kinase inhibitor, is a recently approved therapeutic agent for the treatment of severe AA. Although clinical trials have established the benefit of ritlecitinib, real-world data on its outcome and safety, particularly in patients previously exposed to baricitinib, have been still limited. Accordingly, we conducted a single-center, retrospective study of 22 severe AA patients treated with ritlecitinib 50 mg daily for 24 weeks at Tohoku University Hospital, Japan. Nine patients (41%) were JAK inhibitor (JAKi)-naïve, and 13 (59%) had previously received baricitinib for a median of 19 months. JAKi-naïve patients were significantly younger (median 14 vs. 38 years; p = 0.0143) and had shorter current AA episodes (median 20 vs. 68 months; p = 0.0138), compared with the JAKi-experienced group. Baseline SALT score in each group showed similar distribution. At Week 24, all JAKi-naïve patients achieved SALT₅₀ (a decrease of at least 50% from baseline in the SALT score); 7/9 (78%) attained SALT ≤ 20 and SALT₇₅ (a decrease of at least 75% from baseline in the SALT score). In contrast, among JAKi-experienced patients, only 3/13 (23%) achieved SALT₅₀, and 1/13 (8%) reached SALT₇₅, whereas a reduction in SALT score from baseline was observed in 7 of 13 (54%). Importantly, no patients in both groups experienced SALT worsening or treatment-related adverse events. Our findings highlighted that ritlecitinib is highly effective especially in adolescent JAKi-naïve AA, and although the clinical effect may be limited in JAKi-experienced patients, switching from baricitinib to ritlecitinib remains one of the viable options due to its low risk of disease exacerbation.