Nektar's Rezpeg Shows Promise in Phase IIb Eczema Trial, but Analysts Remain Cautious

Nektar Therapeutics has reported positive results from its Phase IIb REZOLVE-AD trial for rezpegaldesleukin (rezpeg) in atopic dermatitis, sparking a significant surge in the company's stock price. However, industry analysts remain skeptical about the drug's potential to compete in the crowded eczema treatment landscape.

Trial Results and Market Response

The REZOLVE-AD trial, involving over 390 patients with moderate to severe atopic dermatitis, demonstrated that rezpeg achieved its primary endpoint. Patients receiving the highest dose (24 μg/kg every two weeks) experienced a 61% reduction in Eczema Area and Severity Index (EASI) scores after 16 weeks, compared to a 31% reduction in the placebo group.

Nektar's stock price responded dramatically to the news, rising as much as 175% on Tuesday. CEO Howard Robin described the efficacy results as "compelling" and announced plans to present the data at an upcoming scientific congress.

Analyst Skepticism

Despite the positive trial outcomes, analysts at William Blair expressed reservations about rezpeg's market potential. They noted that while the drug's performance was comparable to other investigational treatments for atopic dermatitis, it fell "numerically lower" than Sanofi and Regeneron's blockbuster drug Dupixent.

The analysts also raised concerns about rezpeg's tolerability profile, particularly the high frequency of injection site reactions (30% to 40% of treated patients) compared to Dupixent's single to mid-double digit range. Given the chronic nature of atopic dermatitis, this could represent a "commercial liability" for rezpeg.

Competitive Landscape and Differentiation

Nektar faces significant challenges in differentiating rezpeg in the highly competitive atopic dermatitis market. While most treatments work by blocking immune activation, rezpeg is designed to stimulate regulatory T-cells (Tregs) to dampen inflammatory reactions.

Dr. Jonathan Zalevsky, Nektar's Chief Research and Development Officer, highlighted the drug's rapid onset of response as a potential differentiator from other immune-modulation approaches, such as OX40 pathway inhibitors. However, William Blair analysts maintained that "there is an absence of clear differentiation" for rezpeg in the atopic dermatitis space.

Historical Context and Future Outlook

The positive Phase IIb results come after a tumultuous period for Nektar, including the collapse of its partnership with Eli Lilly in 2023. Nektar subsequently accused Lilly of incorrectly calculating rezpeg's efficacy numbers, leading to ongoing legal proceedings.

As Nektar prepares for potential Phase III trials, the company faces the challenge of proving rezpeg's value in a market dominated by established treatments like Dupixent. The coming months will be crucial as the biotech community closely watches for further developments and regulatory plans for this promising yet controversial drug candidate.