Every current systemic option in atopic dermatitis suppresses an inflammatory pathway. Rezpegaldesleukin does the opposite — it is an interleukin-2 receptor agonist that selectively expands and enhances regulatory T cells, aiming to restore tolerance rather than block a cytokine.
REZOLVE-AD was a phase 2b randomised double-blind placebo-controlled trial at 107 centres in ten countries. It enrolled 398 biologic-naive adults with moderate-to-severe atopic dermatitis — EASI 16 or above, investigator global assessment 3 or above, at least 10% body surface area — and randomised 393 analysed patients 3:3:3:2 to rezpegaldesleukin 24 micrograms/kg every 2 weeks, 18 micrograms/kg every 2 weeks, 24 micrograms/kg every 4 weeks, or placebo for 16 weeks.
All three doses met the primary endpoint. Mean EASI fell 61% on the highest two-weekly dose, 58% on 18 micrograms/kg two-weekly and 53% on the four-weekly regimen, against 31% on placebo. Treatment differences were -30 percentage points (95% CI -41.3 to -18.0), -27 (-38.5 to -15.7) and -22 (-33.3 to -10.3).
The tolerability signal is prominent. Injection-site reactions occurred in 70% of treated patients versus 4% on placebo, though over 99% were mild to moderate and resolved. Eosinophilia, pyrexia, headache and arthralgia were each modestly more common. No serious safety signal and no deaths emerged over 16 weeks.
So: a genuinely novel mechanism with a real effect, and an injection-site reaction rate that will shape whether patients stay on it. Sixteen weeks is short for a chronic relapsing disease, and this is phase 2b.
- A regulatory T cell-expanding agent produced a 61% EASI reduction at 16 weeks versus 31% on placebo
- Injection-site reactions occurred in 70% of treated patients — counsel on this if the drug reaches practice
- The effect was dose-dependent, with two-weekly dosing outperforming four-weekly
- Nothing changes today: this is phase 2b in biologic-naive patients over 16 weeks
- Note the placebo EASI reduction of 31%, which is why uncontrolled reports of eczema treatments mislead
The statistics, in plain English
The placebo arm is the most instructive number here: EASI fell 31% on placebo alone, driven by emollient use, trial attention and natural fluctuation. Any uncontrolled report claiming a 30% improvement in eczema is describing placebo. The treatment differences of 22 to 30 percentage points have confidence intervals that do not cross zero and show a clean dose-response, which strengthens the causal claim. Note also that two sites were excluded for Good Clinical Practice non-compliance and missing data were handled by multiple imputation — both are properly disclosed, and both mean the analysed population is not exactly the randomised one.
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