Efficacy and Safety of Oral Janus Kinase 1 Inhibitor Abrocitinib for Patients With Atopic Dermatitis: A Phase 2 Randomized Clinical Trial

IMPORTANCE: Atopic dermatitis is associated with substantial patient and caregiver burden. Currently available treatments for atopic dermatitis are inadequate or contraindicated for some patients. Abrocitinib (PF-04965842) is an oral Janus kinase 1 selective inhibitor under investigation for the treatment of atopic dermatitis. OBJECTIVE: To investigate the efficacy and safety of abrocitinib for patients with moderate to severe atopic dermatitis. DESIGN, SETTING, AND PARTICIPANTS: A phase 2b, randomized, double-blinded, placebo-controlled, parallel-group trial was conducted from April 15, 2016, to April 4, 2017, at 58 centers in Australia, Canada, Germany, Hungary, and the United States among 267 patients 18 to 75 years of age with a clinical diagnosis of moderate to severe atopic dermatitis for 1 year or more and inadequate response or contraindication to topical medications for 4 weeks or more within 12 months. Efficacy was assessed in the full analysis set, which was a modified intention-to-treat population that included all patients who received 1 dose or more of the study drug except for 4 patients from 1 site. INTERVENTIONS: Participants were randomly assigned 1:1:1:1:1 to receive abrocitinib (200 mg, 100 mg, 30 mg, or 10 mg) or placebo once daily for 12 weeks. MAIN OUTCOMES AND MEASURES: The primary outcome was the proportion of patients achieving an Investigator’s Global Assessment of clear (0) or almost clear (1) with an improvement from baseline of 2 grades or more at week 12. The secondary outcome was the percentage change from baseline in the Eczema Area and Severity Index at week 12. RESULTS: Of the 267 participants, 144 were women (mean [SD] age, 40.8 [16.1] years). At week 12, 21 of 48 patients receiving 200 mg of abrocitinib (43.8%; P < .001, 2-sided), 16 of 54 patients receiving 100 mg of abrocitinib (29.6%; P < .001), and 3 of 52 patients receiving placebo (5.8%) achieved grades of clear or almost clear on the Investigator’s Global Assessment scale with improvement of 2 grades or more; these rates correspond to maximum effect model-based estimates of 44.5% (95% CI, 26.7%-62.3%) for those receiving 200 mg of abrocitinib, 27.8% (95% CI, 14.8%-40.9%) for those receiving 100 mg of abrocitinib, and 6.3% (95% CI, −0.2% to 12.9%) for those receiving placebo. Reductions in the Eczema Area and Severity Index were 82.6% (90% CI, 72.4%-92.8%; P < .001) for those receiving 200 mg of abrocitinib, 59.0% (90% CI, 48.8%-69.3%; P = .009) for those receiving 100 mg of abrocitinib, and 35.2% (90% CI, 24.4%-46.1%) for those receiving placebo. Adverse events were observed in 184 of 267 patients (68.9%); the most frequently reported adverse events (in ≥3 patients in any group) were dermatitis atopic, upper respiratory tract infection, headache, nausea, and diarrhea. Dose-dependent decreases in platelet count were observed but trended upward toward baseline levels after week 4. CONCLUSIONS AND RELEVANCE: Once-daily oral abrocitinib was effective and well tolerated for short-term use in adults with moderate to severe atopic dermatitis. Additional trials are necessary to evaluate long-term efficacy and safety. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02780167