Nektar Therapeutics (NASDAQ:NKTR) on Tuesday revealed topline results from the 36-week induction treatment period of the Phase 2b REZOLVE-AA trial of investigational rezpegaldesleukin.
The global Phase 2b study is being conducted in 92 patients with severe-to-very-severe alopecia areata.
Alopecia areata is an autoimmune condition where the immune system attacks hair follicles, causing sudden, patchy hair loss, usually in coin-sized spots, but it can progress to total scalp (alopecia totalis) or body (alopecia universalis) hair loss.
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Data
The primary endpoint was the mean percentage reduction from baseline in the Severity of Alopecia Tool (SALT) score at Week 36.
Primary and secondary endpoints were assessed at the end of the 36-week induction treatment period.
Both rezpegaldesleukin dose arms more than doubled the SALT score reduction treatment effect observed with placebo, with the majority of patients experiencing hair growth at Week 16 or later.
The primary endpoint narrowly missed statistical significance with the mean percent SALT reduction at Week 36 of 28.2% for the 24 µg/kg rezpegaldesleukin arm, 30.3% for the 18 µg/kg rezpegaldesleukin arm, and 11.2% for placebo (p=0.186 and p=0.121, respectively).
At all timepoints, the rezpegaldesleukin treatment arms separated from placebo in the study.
Four of 92 patients included in the modified intent-to-treat (mITT) analysis were found to have major study eligibility violations that should have disqualified them for randomization into the trial.
Both rezpegaldesleukin treatment arms met statistical significance on the primary endpoint when excluding the four patients with major study eligibility violations.
At Week 36, the mean percent SALT reduction was 29.6% for 24 µg/kg, 30.4% for 18 µg/kg, and 5.7% for placebo (p=0.049 and p=0.042, respectively).
The absolute treatment effect for the rezpegaldesleukin arms was similar with or without the exclusion of eligibility violations.
One patient in the placebo arm with an eligibility violation accounted for the 5.5% difference in the performance of the placebo arm.
Both rezpegaldesleukin treatment arms showed a dose-dependent clinical treatment effect as compared to placebo on the key secondary endpoints of SALT ≤30, SALT≤20, and SALT≤10 and SALT30.
Following 36 weeks, patients who demonstrated hair growth but had not yet reached SALT>20 had the option to continue for an additional 16 weeks of treatment through Week 52 in a blinded extension period.
What Next?
Nektar plans to submit the REZOLVE-AA results for presentation at a medical conference in 2026.
Data from the patients ongoing in the 16-week treatment extension will be available in the early second quarter of 2026.
In September, Nektar Therapeutics shared new data from its ongoing REZOLVE-AD Phase 2b study of rezpegaldesleukin.
The study showed that rezpegaldesleukin met the primary endpoint, with statistically significant improvement in the Eczema Area and Severity Index (EASI) at week 16 compared with placebo.
Key secondary endpoints—including EASI-75, EASI-90, Itch Numerical Rating Scale (NRS), vIGA-AD, and Body Surface Area (BSA)—also demonstrated significant disease reduction in patients with moderate to severe atopic dermatitis.
NKTR Price Action: Nektar Therapeutics shares were down 7.86% at $49.11 at the time of publication on Tuesday, according to Benzinga Pro data.
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