8-K: Nektar's Rezpegaldesleukin Shines in Phase 2b AD Study

Nektar Therapeutics announced positive new data from its REZOLVE-AD Phase 2b study for rezpegaldesleukin in moderate-to-severe atopic dermatitis, meeting primary and key secondary endpoints with a favorable safety profile.

Summary

• The REZOLVE-AD Phase 2b study of rezpegaldesleukin in moderate-to-severe atopic dermatitis met its primary endpoint, showing statistically significant mean Eczema Area and Severity Index (EASI) improvement at Week 16 for all dose arms compared to placebo.
• The high dose (24 g/kg q2w) achieved a 61% mean EASI improvement (p<0.001), the middle dose (18 g/kg q2w) achieved 58% (p<0.001), and the low dose (24 g/kg q4w) achieved 53% (p<0.001), compared to 31% for placebo.
• Key secondary endpoints, including EASI-75, EASI-90, Itch NRS, vIGA-AD 0/1, and Body Surface Area (BSA) improvement, also demonstrated statistical significance for the high dose.
• Patient-reported outcomes such as DLQI, ADCT, Pain NRS, and ADSS Q1 showed significant improvements with the high dose.
• Patients who crossed over from placebo to high-dose rezpegaldesleukin showed deepening responses, with mean EASI reduction increasing from 68% at crossover week 16 to 75% at crossover week 24.
• The safety profile was consistent with previous reports, with the most frequent adverse events being mild, self-resolving injection site reactions, and no new safety concerns identified.
• Rezpegaldesleukin has received Fast Track designation from the FDA in February 2025 for moderate-to-severe atopic dermatitis and in July 2025 for severe alopecia areata.

Sentiment

Score: 9

Explanation: The filing presents overwhelmingly positive clinical trial results for rezpegaldesleukin in atopic dermatitis, meeting primary and multiple key secondary endpoints with statistical significance. The deepening of responses with extended dosing and a favorable safety profile, coupled with Fast Track designations, indicate strong potential for the drug and significant progress towards commercialization. The validation of a novel mechanism of action further enhances the positive sentiment.

Positives

• All rezpegaldesleukin dose arms achieved statistically significant improvement in the primary endpoint of mean % EASI reduction at Week 16 (p<0.001 for all active arms).
• The high dose (24 g/kg q2w) demonstrated a 61% mean EASI improvement, significantly outperforming placebo's 31%.
• Multiple key secondary endpoints, including EASI-75 (42% vs. 17% placebo, p<0.001), vIGA-AD 0/1 (20% vs. 8% placebo, p<0.05), and mean % BSA improvement (54% vs. 17% placebo, p<0.001), were met with statistical significance for the high dose.
• Significant improvements were observed across various patient-reported outcomes (PROs) such as DLQI (72% vs. 54% placebo, p<0.05), ADCT (67% vs. 35% placebo, p<0.001), Pain NRS (45% vs. 22% placebo, p<0.05), and ADSS Q1 (57% vs. 30% placebo, p<0.01) for the high dose.
• Extended dosing beyond 16 weeks in the open-label escape arm showed deepening clinical benefits, with mean EASI reduction reaching 75% at crossover week 24 and EASI-75 responses increasing to 62%.
• The safety profile was favorable, with no observed safety signals for conjunctivitis, facial swelling, oral ulcers, asthma, myocardial infarction, pulmonary embolus, deep venous thrombosis, malignancy, depression, or suicidality.
• Most frequent adverse events were mild, self-resolving injection site reactions, with less than 1% discontinuations due to ISRs.
• The study validates the regulatory T-cell (Treg) mechanism of action and therapeutic potential of rezpegaldesleukin, a novel IL-2 agonist.
• Fast Track designations from the FDA for both moderate-to-severe atopic dermatitis (Feb 2025) and severe alopecia areata (July 2025) underscore the potential of the therapy.

Negatives

• One death occurred in the escape arm (38 y/o female) due to coronary thrombosis/heart failure, although it was assessed as unrelated to study treatment by the Sponsor Drug Safety Committee and independent external experts.
• Eosinophilia was reported by investigators based on laboratory values above the upper limit of normal, leading to one patient discontinuation at the mid-dose of 18 mg/kg q2w.

Risks

• Statements regarding the therapeutic potential of rezpegaldesleukin are based on preclinical and clinical findings and observations and are subject to change as research and development continue.
• Rezpegaldesleukin is an investigational agent, and continued research and development is subject to substantial risks, including negative safety and efficacy findings in future clinical studies, despite positive earlier findings.
• The drug candidate is in clinical development, and the risk of failure is high and can unexpectedly occur at any stage prior to regulatory approval.
• Data reported from ongoing clinical trials are necessarily interim data only, and final results may change based on continuing observations.
• The timing of clinical trials and data availability may be delayed or unsuccessful due to regulatory delays, slower patient enrollment, manufacturing challenges, changing standards of care, evolving regulatory requirements, clinical trial design, clinical outcomes, or competitive factors.
• A Fast Track designation does not increase the likelihood that rezpegaldesleukin will receive marketing approval in the United States.
• Patents may not issue from patent applications, issued patents may not be enforceable, or additional intellectual property licenses from third parties may be required.

Future Outlook

Phase 3 planning for moderate to severe atopic dermatitis is underway. Upcoming data readouts include maintenance data from the AD study in Q1 2026, 1-year off-treatment data in Q1 2027, and Phase 2b 36-week treatment data in severe alopecia areata in December 2025. The company anticipates that the novel Treg mechanism offers an advantage over other novel mechanisms in development for atopic dermatitis.

Management Comments

• "These data from REZOLVE-AD presented today show a rapid onset of treatment effect for both clinician-assessed and patient-reported outcomes following the first few doses of rezpegaldesleukin." Prof. Jonathan Silverberg, MD, PhD, MPH.
• "For the first time, we observe a deepening of clinical effect for patients with extended dosing of investigational therapy beyond 16 weeks, with a strengthening of absolute EASI reduction, along with higher EASI-75 and vIGA 0/1 response rates following 24 weeks of treatment." Prof. Jonathan Silverberg, MD, PhD, MPH.
• "These results build on the body of data generated to-date for rezpegaldesleukin that show the advantage of this novel, broad-based Treg mechanism over other novel mechanisms in development to treat atopic dermatitis." Prof. Jonathan Silverberg, MD, PhD, MPH.
• "With this important validation of a novel Treg mechanism in atopic dermatitis, we look forward to reporting the results in December of this year for rezpegaldesleukin in patients with alopecia areata." Jonathan Zalevsky, Ph.D., Chief Research and Development Officer of Nektar.

Industry Context

Rezpegaldesleukin represents a potential first-in-class regulatory T-cell (Treg) mechanism, offering a novel, broad-based approach to restore immune balance in autoimmune and inflammatory conditions like atopic dermatitis. This differentiated mechanism aims to control overactive immune responses by proliferating and restoring the functionality of Tregs, potentially offering an advantage over other novel mechanisms currently in development for inflammatory skin disorders.

Comparison to Industry Standards

• The study highlights rezpegaldesleukin's novel, broad-based Treg mechanism, which Nektar believes offers an advantage over other novel mechanisms in development to treat atopic dermatitis. Specific comparable companies or projects are not detailed in the filing, but the emphasis is on the unique mechanism of action.
• The safety profile, noting 'no increased risk of conjunctivitis, oral ulcers, asthma, infections or MACE' and 'no observed safety signal for: Conjunctivitis, Facial swelling or erythema, Oral (aphthous) ulcers, Asthma, Myocardial infarction, Pulmonary embolus (PE), Deep venous thrombosis (DVT), Malignancy, Depression / suicidality,' suggests a potentially differentiated safety profile compared to some existing or developing treatments for atopic dermatitis that may carry such risks.

Stakeholder Impact

• **Shareholders:** The strong positive clinical data for a lead product candidate is highly likely to increase investor confidence and potentially drive share price appreciation, offering a positive outlook on future revenue streams.
• **Patients:** The promising efficacy and favorable safety profile of rezpegaldesleukin offer a potential new, first-in-class treatment option for individuals suffering from moderate-to-severe atopic dermatitis, addressing an unmet medical need.
• **Healthcare Providers:** The drug's novel mechanism and positive results could provide clinicians with an additional, differentiated therapeutic tool for managing atopic dermatitis, especially given its Fast Track designation.
• **Employees:** Positive clinical trial results and progression towards Phase 3 studies can boost morale and provide job security, as the company moves closer to potential commercialization.

Next Steps

• Phase 3 planning for moderate to severe atopic dermatitis is underway.
• Maintenance data (comparing q4w vs. q12w regimens) from the ongoing AD study is expected in Q1 2026.
• 1-year off-treatment data from the ongoing AD study is expected in Q1 2027.
• Phase 2b 36-week treatment data in severe alopecia areata is expected in December 2025.

Key Dates

Recommendation

The filing details exceptionally strong Phase 2b clinical trial results for rezpegaldesleukin in atopic dermatitis, demonstrating statistically significant efficacy across primary and multiple key secondary endpoints, including patient-reported outcomes. The observed deepening of responses with extended dosing and a highly favorable safety profile, with no new safety concerns and a lack of adverse events common with other AD treatments, positions this drug as a potential best-in-class or first-in-class therapy. The Fast Track designations further de-risk the regulatory pathway. These factors, combined with the initiation of Phase 3 planning, indicate a high probability of future success and significant market potential, making it a strong buy for long-term investors.

Keywords

Atopic Dermatitis, Rezpegaldesleukin, Phase 2b, Clinical Trial, Nektar Therapeutics, Immunology, Regulatory T-cell, IL-2 Agonist, Eczema, Dermatology, Fast Track Designation