Responder analysis using clinically meaningful thresholds: Post hoc analyses from randomized dupilumab clinical trials in patients with prurigo nodularis

Abstract

Background: Prurigo nodularis (PN) is an intensely pruritic disease characterized by itchy nodules on the trunk/extremities; it is often accompanied by skin pain and sleep disruption with negative impacts on the quality of life (QoL). The patient-reported outcome (PRO) instruments, Worst Itch-Numeric Rating Scale (WI-NRS), Skin Pain-NRS, Sleep-NRS and Dermatology Life Quality Index (DLQI) have been psychometrically validated and the clinically meaningful within-patient improvement thresholds (responder definition) have been established through data pooled from the two Phase-3 trials (PRIME, NCT04183335 and PRIME2, NCT04202679) of dupilumab in adults with PN uncontrolled on topical therapies.

Objectives: To estimate the proportion of dupilumab-treated patients (vs. placebo) achieving clinically meaningful improvement in itch, skin pain, sleep and QoL, either alone or in combination, from the data pooled from PRIME and PRIME2 trials.

Methods: The patient-level data pooled from the two Phase-3 trials (N = 311) were used for this post hoc analysis. Thresholds of clinically meaningful within-patient improvement in PRO instrument scores from baseline at Week 24 used for defining responders were 4 (WI-NRS and Skin Pain-NRS), 2 (Sleep-NRS) and 9 points (DLQI). The proportion of dupilumab-treated patients, versus placebo, achieving the thresholds, and the time taken to achieve the thresholds were evaluated for the individual and combination of PROs.

Results: Responder rates were significantly higher with dupilumab, versus placebo at Week 24 for WI-NRS (58.8% vs. 19.0%, p < 0.0001), Skin Pain-NRS (49.7% vs. 20.9%, p < 0.0001), Sleep-NRS (42.5% vs. 23.4%, p < 0.0001) and DLQI (64.7% vs. 22.8%, p < 0.0001). Proportion of patients achieving simultaneous improvement in symptoms and QoL (24.8% vs. 6.3%, p < 0.0001) were significantly higher in dupilumab-treated patients versus placebo. The time needed for achieving clinically meaningful improvement in symptoms were significantly lower in dupilumab-treated patients, versus placebo.

Conclusions: Significantly greater proportion of dupilumab-treated patients with PN, versus placebo, demonstrated clinically meaningful improvements in PRO measures of symptoms and QoL.