Forty-Eight-Week Real-World Outcomes of Ritlecitinib in Alopecia Areata: Delayed Responses and Predictive Value of Change in SALT Score at Week 24

INTRODUCTION: Alopecia areata (AA) is an autoimmune disease characterized by non-scarring hair loss. Although ritlecitinib has demonstrated efficacy in moderate-to-severe AA, real-world data on 48-week outcomes and predictors of longer-term response remain limited. METHODS: We conducted a retrospective, single-center, observational study of 41 patients with moderate-to-severe AA who received ritlecitinib (50 mg/day) at Osaka Metropolitan University Hospital, Japan. Effectiveness and safety were evaluated for up to 48 weeks. Patients evaluable at week 48 were classified as responders (Severity of Alopecia Tool [SALT] score ≤ 20) or non-responders (SALT score > 20). The predictive value of the change in SALT score from baseline (ΔSALT) for response at week 48 was assessed using receiver operating characteristic (ROC) analysis. RESULTS: At week 48, 39.3% (11/28) and 35.7% (10/28) of patients achieved SALT scores ≤ 20 and ≤ 10, respectively. Responders at week 48 (week-48 responders) showed greater improvement in ΔSALT at week 24 (week-24 ΔSALT) than non-responders (median: - 50.0 vs. 0.0; P = 0.006). Of the 21 patients who had not achieved a SALT score ≤ 20 at week 24, five subsequently achieved this outcome at week 48. ROC analysis showed that week-24 ΔSALT had predictive value for week-48 response (area under the curve [AUC] 0.81; 95% confidence interval 0.619-1.000), with a cutoff of - 40 yielding 81.8% sensitivity and 88.2% specificity. Two patients (4.9%) discontinued ritlecitinib because of adverse events; all other adverse events were mild and did not require treatment discontinuation. CONCLUSIONS: Ritlecitinib showed real-world effectiveness through 48 weeks in patients with moderate-to-severe AA. Delayed responses beyond week 24 were observed, and week-24 ΔSALT may have potential value in predicting response at week 48, although these findings require validation in larger cohorts.