Nektar Therapeutics (NASDAQ:NKTR) reported results from its Phase 2b REZOLVE-AA study evaluating rezpegaldesleukin in patients with severe to very severe alopecia areata, with the trial narrowly missing its primary efficacy endpoint.
The study enrolled 92 patients who were randomly assigned to receive rezpegaldesleukin at doses of either 24 µg/kg or 18 µg/kg, or a placebo. Treatments were administered by subcutaneous injection twice a month over a 36-week period. The main objective was to assess the average percentage reduction in Severity of Alopecia Tool (SALT) scores at week 36.
Patients treated with rezpegaldesleukin recorded mean SALT score reductions of 28.2% at the higher dose and 30.3% at the lower dose, compared with an 11.2% reduction in the placebo group. However, these differences did not reach statistical significance in the primary analysis, with p-values of 0.186 and 0.121, respectively.
Nektar noted that four participants had significant eligibility violations that should have excluded them from randomization. After removing these patients from the analysis, both dosing groups met statistical significance, showing mean SALT score reductions of 29.6% for the 24 µg/kg dose and 30.4% for the 18 µg/kg dose, versus 5.7% for placebo. In this adjusted analysis, p-values were 0.049 and 0.042.
Secondary endpoints indicated dose-related benefits, including higher proportions of patients reaching predefined SALT improvement thresholds. Under the revised analysis, 48.9% of patients receiving the 24 µg/kg dose achieved at least a 30% reduction in SALT score, compared with 19.1% in the placebo arm.
Safety findings were in line with earlier studies. Treatment discontinuation due to adverse events was 1.4% across both rezpegaldesleukin groups, and most treatment-emergent adverse events were classified as mild to moderate and resolved without intervention.
Based on these results, Nektar plans to move rezpegaldesleukin into Phase 3 development for alopecia areata in 2026, supported by the drug’s Fast Track designation from the U.S. Food and Drug Administration. The company also intends to submit the data for presentation at a medical conference next year.
Rezpegaldesleukin is a first-in-class agonist of the interleukin-2 pathway, designed to boost regulatory T-cell activity for the treatment of autoimmune and inflammatory conditions.