Nektar Therapeutics (NKTR) announced positive results from its Phase 2b REZOLVE-AA study of Rezpegaldesleukin in patients with severe-to-very-severe Alopecia areata or patchy hair loss. The trial demonstrated hair regrowth, establishing proof-of-concept for the first-in-class IL-2 pathway agonist.
Alopecia areata is an autoimmune disorder where the immune system attacks hair follicles, leading to patchy or complete hair loss. Current therapies, including JAK inhibitors, are limited by safety concerns and relapse rates, leaving a significant unmet need for biologics that can deliver durable efficacy.
The REZOLVE-AA trial enrolled 92 patients randomized to receive one of the two doses of Rezpegaldesleukin or placebo, administered subcutaneously twice monthly for 36 weeks.
The primary endpoint measured reduction in Severity of Alopecia Tool or SALT scores. Both treatment arms more than doubled the effect seen with placebo, with mean SALT reductions of 28.2% and 30.3% compared to 11.2% for placebo. When excluding four patients with major eligibility violations, the results reached statistical significance, with reductions of 29.6% and 30.4% versus 5.7% for placebo.
Secondary endpoints reinforced the benefit, with higher proportions of patients achieving SALT scores =30, =20, and =10. Investigators noted regrowth of scalp hair as well as eyebrows and eyelashes.
Importantly, Rezpegaldesleukin was well tolerated, with nearly all adverse events mild to moderate and self-resolving. Discontinuation was only 1.4%.
Nektar plans to advance Rezpegaldesleukin into Phase-3 development in 2026, leveraging its FDA Fast Track designation for Alopecia areata. Data from the ongoing 16-week extension will be available in early second quarter of 2026, and the results are slated for presentation at a medical conference later that year.
Rezpegaldesleukin is also being studied in atopic dermatitis and type-1 diabetes, broadening its potential as a regulatory T-cell stimulator across multiple autoimmune conditions.
NKTR has traded between $6.45 and $66.92 over the past year. The stock is currently trading in the pre-market at $58.39, up 9.55%.
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