The US Food and Drug Administration (FDA) has granted fast track designation to Nektar Therapeutics’ rezpegaldesleukin as a treatment for alopecia areata (AA).

The regulator’s decision specifically applies to adult and paediatric patients aged 12 years and older who weigh at least 40 kilograms and are living with severe-to-very severe cases of the autoimmune disease.

Approximately 700,000 people in the US currently have some form of AA, which occurs when a patient’s own immune system attacks hair follicles, resulting in varying degrees of hair loss.

Rezpegaldesleukin, which has already been granted FDA fast track designation for moderate-to-severe atopic dermatitis, is designed to target the interleukin-2 receptor complex in the body, stimulating the proliferation of inhibitory immune cells called Tregs and potentially bringing the immune system back into balance.

The phase 2b REZOLVE-AA trial is currently evaluating the drug in patients with severe-to-very severe AA who have at least 50% scalp involvement and have not previously been treated with a JAK inhibitor or other biologic.

The primary efficacy endpoint of the study will evaluate the mean percent change in the Severity of Alopecia Tool (SALT) score at the end of the 36-week induction period.

Jonathan Zalevsky, senior vice president and chief research and development officer at Nektar, said: “AA 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.

“We remain on track to announce top-line data in December from our ongoing REZOLVE-AA phase 2b study for rezpegaldesleukin in AA, and we look forward to the opportunity to collaborate quickly with the agency on a potential registrational programme following the completion of phase 2.”