Nektar's Rezpegaldesleukin Shows Hair Regrowth in Alopecia Areata in Phase 2 Extension Study
Overcoming Limitations of Phase 2 and Achievements of the Extension Study
Nektar Therapeutics has announced data from a 52-week extension study of its Phase 2b trial of rezpegaldesleukin (NKTR-358), an immunomodulatory agent being developed for the treatment of alopecia areata. While the 36-week primary endpoint did not achieve statistical significance, this 16-week blinded extension phase demonstrated that hair regrowth effects deepen with longer duration of treatment. Tracking 31 responder patients, significant improvements in treatment response were observed in both the low-dose and high-dose groups. This validates the value of the pipeline, which had stalled after initial setbacks, and provides a basis for advancing to later-stage clinical trials.
Improvement in Hair Regrowth Indicators with Extended Treatment Duration
At the 52-week treatment mark, 29% of patients in the low-dose rezpegaldesleukin group and 31% in the high-dose group achieved a Severity of Alopecia Tool (SALT) score of 20 or less, indicating greater than 80% hair recovery. In contrast, no patients receiving placebo after 36 weeks met this criterion. Hair recovery is a key indicator of quality of life for patients with severe alopecia areata, and the fact that treatment response is enhanced with long-term administration is an encouraging result. Nektar has confirmed through this trial that the drug's efficacy accumulates over time, and the importance of treatment duration will be redefined in future clinical trial designs.
Enhanced Safety Profile Compared to Existing JAK Inhibitors
In this extension trial, adverse events were mostly mild injection site reactions, and no patients discontinued treatment due to adverse events. This is a key differentiator from olumiant (baricitinib) and leqselvi (deuruxolitinib), the standard-of-care JAK inhibitors for alopecia areata, which carry a risk of serious blood clotting. The medical community has been seeking safer treatments with novel mechanisms of action due to concerns about the adverse effects of JAK inhibitors, and rezpegaldesleukin, which activates regulatory T cells (Tregs), may be an alternative. Demonstrating excellent tolerability with long-term administration will be a strong competitive advantage in the future market.
Restoring Investor Confidence and Opening Up Funding Opportunities
On the day of the positive clinical data announcement, Nektar's stock price surged 25% during trading, exceeding $100 per share. This is a significant turning point for Nektar, which had undergone restructuring after the failed co-development with Bristol Myers Squibb (BMS) in 2022. In a situation where the co-development agreement with Eli Lilly was terminated in 2017 and the company is pursuing independent development, this achievement will serve as a platform for securing additional investment or establishing partnerships for Phase 3 trials. The market views the clinical trial results as evidence that Nektar's independent immunomodulatory platform technology is effective.
Nektar Therapeutics' (NKTR) rezpegaldesleukin demonstrated in a Phase 2 extension study for severe alopecia areata that approximately 30% of patients achieved a SALT score of 20 or less at week 52, proving its unique pharmacokinetic properties with efficacy accumulating and enhancing with long-term administration. This presents a potential safe alternative treatment option to existing JAK inhibitor competitors such as olumiant (Olumiant) and leqselvi (Leqselvi) in the global alopecia areata market, estimated at $3.32 billion in 2024, by circumventing the major limitation of these drugs: the risk of blood clotting. The clinical re-evaluation of this asset, which is being independently developed after the termination of the partnership with Eli Lilly in 2023 and the data manipulation lawsuit, provides a crucial momentum for enhancing Nektar's corporate value and securing funding for the design and independent development of Phase 3 trials. In the medium to long term, it can serve as academic evidence that the biological mechanism of regulatory T cell (Treg) activation can be extended to the treatment of autoimmune diseases in general, and is expected to maximize the partnership attractiveness of Nektar, which is preparing to enter a large-scale Phase 3 trial.
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