REZOLVE-AD was an international double-blind placebo-controlled phase 2b trial in moderate-to-severe atopic dermatitis. Of 398 enrolled, 393 were analysed across three rezpegaldesleukin regimens and placebo.
All three doses met the primary endpoint, with a clean dose-response. Mean percentage EASI change at week 16 was -61% for 24 μg/kg every two weeks, -58% for 18 μg/kg every two weeks, and -53% for 24 μg/kg every four weeks, against -31% for placebo. Treatment differences were -30 percentage points (interval -41.3 to -18.0), -27 and -22 respectively.
The mechanism is what distinguishes this from the current field. Dupilumab, tralokinumab and the JAK inhibitors all suppress inflammatory signalling; rezpegaldesleukin expands regulatory T cells, aiming to restore control rather than remove a driver. If that holds up, it implies a different long-term safety profile — though sixteen weeks says nothing about that.
Injection-site reactions occurred in 223 of 320 treated patients (70%) against three of 73 on placebo (4%). More than 99% were mild to moderate and resolved. Eosinophilia at 8%, pyrexia at 6% and arthralgia at 5% all exceeded placebo modestly. No excess of serious or severe events, and no deaths.
- Phase 2b, sixteen weeks — not a licence and not long-term data
- Clean dose-response across three regimens strengthens the finding
- 70% injection-site reactions, almost all mild to moderate and resolving
- Treg-enhancing rather than cytokine-blocking — a genuinely different mechanism
- The 31% placebo EASI improvement is a reminder of how much AD trials regress
The statistics, in plain English
The 31% improvement on placebo is worth as much attention as the 61% on treatment. Atopic dermatitis trials consistently show large placebo responses — emollient use, trial attention, and natural fluctuation all contribute — which is why the 30-point difference, not the 61%, is the effect. A dose-response gradient across three regimens is one of the stronger internal consistency checks a phase 2 trial can offer.
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