FDA grants fast track to rezpegaldesleukin for severe alopecia areata in ages 12 and up

FDA grants fast track to rezpegaldesleukin for severe alopecia areata in ages 12 and up | Image credit: Contemporary Pediatrics

On July 29, 2025, the FDA granted fast track designation to the investigational therapy rezpegaldesleukin (Rezpeg; Nektar Therapeutics) for the treatment of severe to very severe alopecia areata (AA) in adults and pediatric patients 12 years or older with a weight of at least 40 kg.¹

Rezpegaldesleukin is a biologic candidate designed to target the IL-2 receptor complex to stimulate proliferation of regulatory T cells (Tregs), which may help restore immune tolerance in autoimmune conditions such as AA. Nektar noted that results from multiple trials showed the therapy safely and dose-dependently increased Treg populations.

"We are pleased that rezpegaldesleukin has been granted fast track designation for the treatment of alopecia areata, adding to its fast track designation in atopic dermatitis," said Jonathan Zalevsky, PhD, senior vice president and chief research and development officer at Nektar. "Alopecia areata is a chronic, systemic, immune-mediated inflammatory disease, and there is an urgent need for novel mechanistic approaches that could treat the underlying pathogenesis of this disorder."

The FDA’s fast track designation is intended to facilitate the development of treatments for serious conditions that address an unmet medical need. With this designation, rezpegaldesleukin becomes eligible for more frequent meetings with the FDA, written communications on clinical trial design, and potential rolling and priority review.

Phase 2b Rezolve AA study of rezpegaldesleukin

The phase 2b Rezolve AA trial (NCT06340360) was initiated in March 2024 and enrolled approximately 90 patients across 30 sites worldwide, including in Poland (62%), Canada (24%), and the United States (14%).

Participants were randomly assigned to receive one of 2 dose regimens of rezpegaldesleukin or placebo over a 36-week induction period. Patients were eligible for the study if they had a diagnosis of severe to very severe AA, defined as 50% or greater scalp involvement based on the Severity of Alopecia Tool (SALT) score at both screening and random assignment. Individuals with diffuse alopecia or an unstable disease course in the previous 6 months were excluded.

The study's primary end point is the mean percent change in SALT score at week 36. Secondary outcomes include the proportion of patients achieving 50% or more reduction in SALT score, mean SALT improvement at other time points, and the proportion of patients reaching SALT-20 (defined as an absolute SALT score of 20 or less).

"We remain on track to announce top-line data in December from our ongoing Rezolve AA phase 2b study for rezpegaldesleukin in alopecia areata, and we look forward to the opportunity to collaborate quickly with the agency on a potential registrational program following the completion of phase 2," added Zalevsky.

February 2025 fast track designation for atopic dermatitis

Rezpegaldesleukin previously received fast track designation in February 2025 for the treatment of moderate to severe atopic dermatitis (AD) in patients 12 years or older whose condition is not adequately controlled with topical therapies or where such therapies are not advisable.²

According to Nektar, rezpegaldesleukin showed rapid improvement in disease outcomes during a 12-week induction phase and continued benefits lasting 36 weeks after treatment cessation. Early data presented at the 2023 European Academy of Dermatology and Venereology Congress demonstrated significant improvements in Eczema Area and Severity Index (EASI) scores and body surface area affected (P = .002 and P = .0158, respectively).

The ongoing phase 2b REZOLVE-AD study (NCT06136741) has enrolled 398 patients with moderate to severe AD. Patients are randomly assigned to one of 3 induction doses or placebo for 16 weeks. Those who meet an EASI threshold are then randomly assigned again to a maintenance regimen administered once monthly or once every 3 months.

References

1. Nektar Therapeutics receives fast track designation for rezpegaldesleukin for the treatment of severe-to-very severe alopecia areata. Press release. Nektar Therapeutics. July 29, 2025. Accessed July 29, 2025. https://ir.nektar.com/news-releases/news-release-details/nektar-therapeutics-receives-fast-track-designation-0
2. Fitch J. FDA grants rezpegaldesleukin fast track to treat moderate, severe atopic dermatitis. Contemporary Pediatrics. February 10, 2025. Accessed July 29, 2025. https://www.contemporarypediatrics.com/view/fda-grants-rezpegaldesleukin-fast-track-to-treat-moderate-severe-atopic-dermatitis