Nektar Therapeutics (NASDAQ:NKTR) reported mixed Phase 2b results for rezpegaldesleukin in severe-to-very-severe alopecia areata, showing meaningful clinical activity but narrowly missing the trial’s primary endpoint in the modified intent-to-treat population.
The 36-week REZOLVE-AA study enrolled 92 patients and tested two dose levels of the IL-2 pathway modulator.
Patients receiving rezpegaldesleukin achieved mean improvements in SALT hair-loss scores of 28.2% for the 24 µg/kg arm and 30.3% for the 18 µg/kg arm, compared with 11.2% for placebo.
Although the reductions trended strongly in favor of treatment, the results did not reach statistical significance under the pre-specified analysis.
Nektar said four patients had major eligibility violations that materially affected variance in the dataset.
When those individuals were excluded, both dose arms met the primary endpoint: 29.6% and 30.4% improvements versus 5.7% for placebo, with p-values of 0.049 and 0.042, respectively.
Key secondary outcomes—including SALT30 and proportions achieving SALT thresholds of ≤30, ≤20, and ≤10—consistently favored rezpegaldesleukin.
Safety was described as well tolerated with mostly mild or moderate adverse events and a low 1.4% discontinuation rate across treatment groups.
Nektar said it plans to move the program into Phase 3 in 2026 and will present additional efficacy and safety analyses at a medical meeting next year as it continues refining dose selection and development strategy.