Nemolizumab missed its endpoint in dialysis itch, but not by much at week 4

Design

12-week randomised, placebo-controlled trial of two doses

Population

258 haemodialysis patients with chronic kidney disease-associated pruritus

Primary outcome

proportion with a 4-point or greater improvement in Worst Itch Numerical Rating Scale at week 12

Effect

60 mg 47.7% (P = 0.069), 30 mg 38.5% (P = 0.37) vs placebo 32.4%

NIKAIA-1 randomised 258 haemodialysis patients with chronic kidney disease-associated pruritus to nemolizumab 30 mg, 60 mg or placebo every four weeks for 12 weeks. Nemolizumab targets interleukin-31, the cytokine most directly implicated in itch signalling, and already works in atopic dermatitis and prurigo nodularis.

The primary endpoint - the proportion achieving a 4-point or greater improvement in worst itch at week 12 - was not met: 47.7% on 60 mg (P = 0.069), 38.5% on 30 mg (P = 0.37), against 32.4% on placebo. Two things sit underneath that. The week-4 separation was much wider: 24.3% to 26.6% on nemolizumab reached the 4-point threshold against 7.4% on placebo. And itch-related quality of life on Skindex-10 improved with 60 mg (nominal P < 0.01). Drug-related adverse events were comparable across groups.

This is a trial whose placebo arm caught up, which is the standard hazard of itch trials - a third of placebo patients reaching a 4-point improvement over 12 weeks is a high bar. For now, dialysis-associated itch management does not change: optimise dialysis adequacy and phosphate, treat any xerosis properly, and use what has evidence in this population. Keep nemolizumab in the category of a promising mechanism with a failed trial, not a treatment to request.

• Rule out and treat xerosis and coexisting eczema before calling itch uraemic
• Review dialysis adequacy, calcium, phosphate and parathyroid hormone with the renal team
• Ask about sleep loss - it is often the symptom worth treating rather than the itch score
• Do not offer nemolizumab for this indication; the trial did not meet its endpoint
• Document the itch score at each visit so a treatment trial has a baseline to beat

Why it matters

An IL-31 antibody failing here suggests uraemic itch is not simply the same pathway as eczema itch.

Don't overread it

The primary endpoint was negative, and the quality-of-life and week-4 findings are secondary and nominally significant only.

The statistics, in plain English

A P value of 0.069 is not evidence of benefit; it is a result that did not clear the threshold the trial set, and calling it a near miss is how negative trials get read as positive. The week-4 gap of roughly 25% versus 7% was large, but an early difference that closes by week 12 usually means the placebo response is still rising, not that the drug stopped working. Nominal P values on secondary endpoints carry no protection against chance.

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