The relationship between pruritus and the clinical signs of psoriasis in patients receiving tofacitinib

Abstract

Objective: Tofacitinib is a novel, oral Janus kinase inhibitor being investigated for psoriasis. This study assessed the relationship between pruritus and clinical signs of psoriasis (assessed by Physician’s Global Assessment [PGA]) in patients with moderate-to-severe chronic plaque psoriasis receiving tofacitinib.Methods: In this 16-week (12-week treatment period, 4-week observation period), double-blind, placebo-controlled, phase IIb study (NCT00678210), 197 patients were randomized to tofacitinib 2, 5 or 15 mg BID, or placebo. Pruritus was patient assessed using the Itch Severity Score (ISS), a 0–10 (10 = worst itching) rating scale recorded daily from baseline to week 2 and at study visits. Mediation modeling was used to determine relationships between ISS (average score weeks 2–12), PGA (average score weeks 2–12) and treatment groups.Results: Mediation analysis showed that 70.2–80.5% (p < 0.001 versus placebo) of tofacitinib’s effect on pruritus was direct, and mostly independent of improvements in erythema, induration and scaling. ISS measurements had acceptable test–retest reliability. Correlation analyses with clinical outcomes supported the validity of the ISS as a pruritus measure.Conclusions: Tofacitinib has a direct, beneficial effect on patient-reported pruritus independent from improvements in clinician-reported psoriasis severity signs. The ISS demonstrated favorable psychometric characteristics, supporting its use as a pruritus assessment tool.