Nektar Therapeutics (NASDAQ:NKTR) saw its shares rise roughly 20% after the company reported positive 52-week data from the Phase 2b REZOLVE-AA study of rezpegaldesleukin in patients with severe-to-very-severe alopecia areata.
The updated results focus on patients who continued twice-monthly dosing into a blinded extension period. In the 18 microgram per kilogram extension arm, 29% of patients achieved a new Severity of Alopecia Tool (SALT) Score of 20 or less from week 36 to week 52. In the 24 microgram per kilogram extension arm, 31% of patients reached that same endpoint over the same interval. A SALT Score of 20 or less corresponds to at least 80% scalp coverage by hair.
Looking at the overall study population at week 52, the proportions achieving SALT Score 20 or less were 25.8% in the low-dose rezpegaldesleukin arm and 27.6% in the high-dose arm, compared with 6.7% for placebo. The reported p-value for that comparison was 0.049.
The trial enrolled 92 patients with severe-to-very-severe alopecia areata. After completing a 36-week induction phase, 31 patients entered a blinded 16-week extension period that continued through week 52.
Rezpegaldesleukin is described by the company as a first-in-class interleukin-2 pathway agonist and regulatory T-cell biologic. Nektar reported that 94% of patients completed the treatment extension and that the favorable safety profile observed with twice-monthly dosing was maintained across the full 52-week period.
Additional responder data at week 52 show that patients attaining a SALT Score of 30 or less were 30.2% in the low-dose arm and 35.0% in the high-dose arm, versus 8.4% with placebo. A SALT Score of 30 or less indicates the patient has at least 70% of the scalp covered by hair. The p-value reported for the SALT Score 30 or less comparison was 0.023.
Nektar stated that these outcomes support moving rezpegaldesleukin into late-stage development for alopecia areata. The company plans to submit the REZOLVE-AA results for presentation at a medical conference in 2026.
Clear summary
Nektar disclosed 52-week data from its Phase 2b REZOLVE-AA study showing higher rates of clinically defined hair regrowth with twice-monthly rezpegaldesleukin versus placebo. The data include both SALT Score 20 and SALT Score 30 responder rates, completion and safety metrics, and will be prepared for a 2026 medical conference presentation. The announcement coincided with a roughly 20% increase in the company’s stock price.
Key points
- Study responder rates at week 52: SALT Score ≤20 achieved by 25.8% (low dose) and 27.6% (high dose) versus 6.7% for placebo (p=0.049).
- Extension-arm improvements from week 36 to week 52: 29% in the 18 µg/kg arm and 31% in the 24 µg/kg arm reached SALT Score ≤20 with continued dosing.
- Safety and retention: 94% of patients completed the 16-week extension and twice-monthly dosing maintained a favorable safety profile through 52 weeks.
Sectors impacted
- Biotechnology and pharmaceuticals - clinical development and product pipeline advancement.
- Healthcare - potential therapeutic options for autoimmune-driven hair loss if later-stage development is successful.
- Financial markets - biotech equity performance reacts to clinical data disclosures.
Risks and uncertainties
- Sample size and extension population - while 92 patients were enrolled overall, only 31 continued into the blinded 16-week extension, which may limit the robustness of extension-phase findings and their generalizability.
- Statistical margins - the SALT Score ≤20 comparison versus placebo reported a p-value of 0.049, which is near the conventional 0.05 threshold for statistical significance.
- Clinical development path - advancement into late-stage testing is supported by the company, but future trial outcomes and regulatory considerations remain uncertain.
No additional information beyond the data and plans described by the company was included in the disclosure of these results.