Efficacy and Safety of Ritlecitinib in the Asian Subpopulation of the <scp>ALLEGRO</scp> ‐2b/3 and <scp>ALLEGRO</scp> ‐ <scp>LT</scp> Clinical Studies for Alopecia Areata

Ritlecitinib is an oral JAK3/TEC family kinase inhibitor approved for individuals aged ≥ 12 years with severe alopecia areata. Here we report interim efficacy and safety results with ritlecitinib up to Month 24 in the Asian subpopulation from the ALLEGRO phase 2b/3 and ALLEGRO-LT studies. Data are reported for participants with Severity of Alopecia Tool score ≥ 50 who received ritlecitinib 50 mg with (200/50-mg group) or without (50-mg group) an initial 4-week 200-mg daily loading dose in ALLEGRO-2b/3, and continued ritlecitinib 50 mg in ALLEGRO-LT. In long-term studies, it is common for summaries at later time points to reflect participants who remained in the study, tolerated the drug, and had a positive treatment response. To account for this, efficacy summaries were presented both as observed and by using the last observation carried forward method. At Month 12, 51.7% and 44.7% (last observation carried forward) of Asian participants in the 50-mg (n = 58) and 200/50-mg groups (n = 47), respectively, achieved Severity of Alopecia Tool score ≤ 20 (≤ 20% scalp hair loss); the respective proportions were 50.0% and 47.8% at Month 24. Of participants who achieved Severity of Alopecia Tool score ≤ 20 at Month 12 in the 50-mg and 200/50-mg groups, 68.2% and 86.7% sustained this response through Month 24, respectively. At Month 12, 74.0% and 57.9% of participants in the 50-mg and 200/50-mg groups, respectively, had an eyebrow hair regrowth response; at Month 24, the proportions were 72.0% and 48.7%. At Month 12, 65.1% and 54.1% of participants in the 50-mg and 200/50-mg groups, respectively, had an eyelash hair regrowth response; the proportions were 65.1% and 52.8% at Month 24. The proportion of participants with a Patients' Global Impression of Change response of "moderately" or "greatly" improved since baseline increased through Month 24 in both groups. Ritlecitinib had an acceptable safety profile, consistent with that in the overall population. Overall, ritlecitinib 50 mg (±200-mg loading dose) demonstrated clinically meaningful and sustained efficacy through Month 24 in the Asian subpopulation, consistent with results in the overall population. Trial Registration: ClinicalTrials.gov: NCT04006457.