FDA Speeds Development of Hair Loss Drug Rezpegaldesleukin

Key Takeaways

• Rezpegaldesleukin was granted FDA Fast Track designation for treating severe-to-very severe alopecia areata in patients ≥12 years old and ≥40 kg.

• The agent works by targeting IL-2 receptors to increase Tregs, aiming to restore immune regulation in autoimmune hair loss.

• Phase 2b topline data from the REZOLVE-AA trial are expected in December 2025.

The FDA has granted Fast Track designation to the investigational biologic rezpegaldesleukin (Nektar Therapeutics) for the treatment of severe-to-very severe alopecia areata (AA) in adults and adolescents aged 12 and older who weigh at least 40 kg.

Rezpegaldesleukin, according to a news release, targets the IL-2 receptor complex to stimulate the proliferation of regulatory T cells (Tregs) and restore immune balance in autoimmune conditions. According to Nektar, the agent has shown a dose-dependent and safe increase in Treg levels in multiple clinical trials.

“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,” said Jonathan Zalevsky, PhD, Senior Vice President and Chief Research & Development Officer at Nektar Therapeutics, said in the news release. “We remain on track to announce topline data in December from our ongoing REZOLVE-AA Phase 2b study for rezpegaldesleukin in alopecia areata. We look forward to the opportunity to collaborate quickly with the agency on a potential registrational program following the completion of phase 2."

Rezpegaldesleukin has also received FDA Fast Track status for atopic dermatitis. 

Source: Nektar press release. July 29, 2025.