723 - Efficacy of ritlecitinib in patients with alopecia areata by extent of hair loss at baseline: post hoc analysis of the phase 3 long-term ALLEGRO-LT study

Abstract Introduction/Background The oral JAK3/TEC family kinase inhibitor ritlecitinib demonstrated efficacy and safety in patients aged ≥12 years with alopecia areata (AA) with ≥50% hair loss in the ALLEGRO phase 2b/3 study. ALLEGRO-LT is an ongoing phase 3 open-label study investigating the long-term safety and efficacy of ritlecitinib in patients aged ≥12 years with AA with ≥25% hair loss. Objectives This post hoc analysis of ALLEGRO-LT evaluated the efficacy of ritlecitinib through Month 15 in patients with AA by the extent of scalp hair loss at baseline. Methods The open-label, multicenter, long-term ALLEGRO-LT study (NCT04006457) enrolled patients into two arms: (1) roll-over patients who had received study intervention in either the ALLEGRO phase 2a study (NCT02974868) or phase 2b/3 study (NCT03732807), and (2) de novo patients who were aged ≥12 years with AA with ≥25% scalp hair loss at baseline and had not participated in either study. This post hoc analysis only included patients in the de novo cohort. All patients received an initial 4-week loading dose of ritlecitinib 200 mg once-daily (QD) followed by ritlecitinib 50 mg QD. Outcomes included median Severity of Alopecia Tool (SALT) score over time and the proportions of patients with SALT score ≤20 (≤20% scalp hair loss) and ≤10 at Month 15. Patients were stratified by extent of scalp hair loss at baseline (measured by SALT score) as follows: 25 to <50, 50 to <75, 75 to <90, 90 to <95, and 95 to 100. Analyses were based on observed data. Results 1052 patients were enrolled in ALLEGRO-LT, of whom 447 patients received ritlecitinib in the de novo arm. Of the 447 de novo patients, 26.6% (n=119), 16.8% (n=75), 9.2% (n=41), 2.9% (n=13), and 44.5% (n=199) had baseline SALT scores 25 to <50, 50 to <75, 75 to <90, 90 to <95, and 95 to 100, respectively. Patients with baseline SALT score ≥95 generally had longer mean duration of AA episode (3.47 years) and disease duration (10.86 years) than patients with SALT score <50 at baseline (2.53 and 8.79 years, respectively). A greater proportion of patients with baseline SALT score <50 had active shedding at baseline (49.6%) vs patients with baseline SALT score ≥95 (11.6%). Across all groups, median SALT scores improved (decreased) from baseline through Month 15. At Month 15, median SALT scores were 1.0, 1.2, 1.4, 2.4, and 30.9 for the 25 to <50, 50 to <75, 75 to <90, 90 to <95, and 95 to 100 groups, respectively. At Month 15, 93.0% (93/100), 87.7% (57/65), 88.2% (30/34), 83.3% (10/12), and 43.9% (68/155) of patients, respectively, achieved SALT scores ≤20, and 81.0% (81/100), 76.9% (50/65), 73.5% (25/34), 75.0% (9/12), and 33.5% (52/155) of patients, respectively, achieved SALT score ≤10. Conclusions After 15 months of ritlecitinib treatment, patients with less than 95% hair loss at baseline reached median SALT scores of <2.4, reflecting almost complete scalp hair regrowth. More refractory disease was seen in the subset of patients with extensive (≥95%) hair loss at baseline; however, over one third of these patients achieved clinically meaningful SALT response (SALT ≤20 and SALT ≤10) at Month 15. Overall, ritlecitinib was efficacious in patients with AA with ≥25% hair loss including those with extensive hair loss at baseline.