Rezpegaldesleukin Hair Regrowth Climbs Through 1 Year in AA: David Rosmarin, MD

Rezpegaldesleukin, an investigational regulatory T cell (Treg)-inducing interleukin-2 receptor agonist, continued to increase hair regrowth from week 36 through week 52 in patients with severe to very severe alopecia areata (AA) in the phase 2b REZOLVE-AA trial.1 David Rosmarin, MD, associate professor, chair of the Department of Dermatology, and Kampen-Norins Scholar in Dermatology at Indiana University School of Medicine, discussed the results with HCPLive.

Rosmarin presented the analysis at the European Academy of Dermatology and Venereology (EADV) Congress 2026 in Vienna, Austria, following 52-week extension results reported earlier this year. REZOLVE-AA (NCT06340360) randomized 92 JAK inhibitor-naive adults with a Severity of Alopecia Tool (SALT) score of 50 or greater to subcutaneous rezpegaldesleukin 24 µg/kg (n = 35), 18 µg/kg (n = 37), or placebo (n = 20) every 2 weeks for 36 weeks.1,2 Patients with SALT above 20 at week 36 were eligible for a blinded 16-week treatment extension, which 31 patients entered.

"The fact that there is a deepening of response, that we have people improving, even 6 months after stopping treatment, is really remarkable and very different from the JAK inhibitor class of medicines that we have now, and I think it really speaks to the value add for stimulating Tregs and a truly novel mechanism," Rosmarin said.

In the extension, 4 of 13 (31%) patients receiving 24 µg/kg and 4 of 14 (29%) receiving 18 µg/kg newly achieved SALT 20 or lower, compared with 0 of 4 receiving placebo.1 Across the study population, SALT 20 or lower rates rose from 15.6% to 27.6% with 24 µg/kg and from 14.8% to 25.8% with 18 µg/kg between weeks 36 and 52, while placebo remained at 6.7%.

At week 52, SALT 30 or lower was achieved by 35.0%, 30.2%, and 8.4% of patients receiving 24 µg/kg, 18 µg/kg, and placebo, respectively, and SALT50 by 38.8%, 37.7%, and 13.6%.1 Week 52 results for patients outside the extension were carried forward from week 36, with multiple imputation for missing extension data. Rosmarin noted responses had not yet plateaued by week 52.

Overall, 94% of extension patients completed the 16-week period, and no increased risk of conjunctivitis, oral herpes, or malignancy was observed across a combined database of more than 1,000 rezpegaldesleukin-treated patients.1 Rosmarin said the phase 3 program is set to begin at the end of 2026. These congress data have not been peer reviewed.

Disclosures for Rosmarin include AbbVie, Abcuro, Almirall, AltruBio, Amgen, Arena, Astria, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, and others.

References

1. Rosmarin D, Ungar B, Mesinkovska N, et al. Rezpegaldesleukin, a novel regulatory T cell-inducing biologic, demonstrates efficacy and safety in severe-to-very-severe alopecia areata: 52-week results from the phase 2b REZOLVE-AA study. Abstract 1872. Presented at: EADV Congress 2026; September 30–October 3, 2026; Vienna, Austria.

2. A phase 2b study to evaluate rezpegaldesleukin (rezpeg) in the treatment of severe to very severe alopecia areata in adult patients (REZOLVE AA). ClinicalTrials.gov identifier: NCT06340360. Accessed October 13, 2026. https://clinicaltrials.gov/study/NCT06340360