Breaking the Itch-Scratch Cycle in Prurigo Nodularis with IL-31 Blockade

Original Article: Phase 3 Trial of Nemolizumab in Patients with Prurigo Nodularis

What are the key takeaways of this article?

Prurigo nodularis (PN) is a chronic skin condition marked by severe, relentless itching and hard bumps caused by repeated scratching. Many patients describe it simply as “chronic itch” or are told they have “neurodermatitis.” PN is not the same as atopic dermatitis (eczema), although the two can overlap. In PN, itch is the central problem, often leading to poor sleep, anxiety, depression, and major reductions in quality of life (QoL).

Research over the past decade has identified interleukin-31 (IL-31) as a key driver of PN. IL-31 is an immune signal released by inflammatory cells that directly activates itch-sensing nerves in the skin. In PN, IL-31 levels are elevated in affected skin and closely correlate to  itch severity, helping explain why itch in PN is so intense and persistent.

This phase 3 clinical trial evaluated nemolizumab, an injectable biologic that blocks IL-31. The double-blind, randomized, placebo-controlled trial enrolled 274 adults with moderate-to-severe PN. Participants were randomized in a 2:1 ratio to receive nemolizumab or placebo for 16 weeks, with injections given every four weeks. The primary outcomes assessed were meaningful itch reduction and improvement in skin lesions, along with patient-reported sleep and quality-of-life measures.

By week 16, the results showed more than half of patients treated with nemolizumab had major itch improvement, compared with about one-fifth of those receiving placebo. Importantly, itch relief began early, often within the first four weeks, and was followed by improvements in sleep and skin lesions. Patients also reported better QoLand less overall disease burden. Nemolizumab was generally well tolerated, with mostly mild side effects such as headache or eczema-like symptoms. Serious side effects were uncommon.

Overall, this study provides strong evidence that PN is a biologically driven disease, not simply a behavioural or psychological condition. By targeting a key itch pathway rather than broadly suppressing inflammation, nemolizumab offers a new, mechanism-based treatment approach. These findings represent an important shift in how chronic itch disorders like PN are understood and treated.

Publication Date: March 5, 2026

Reference:

Kwatra SG, Yosipovitch G, Legat FJ, et al. Phase 3 trial of nemolizumab in patients with prurigo nodularis. N Engl J Med. 2023;389:1579–1589.

Summary By: Nicole Chu