Despite Nektar’s share price shooting up as much as 175% on Tuesday, William Blair maintained that “there is an absence of clear differentiation” for rezpegaldesleukin in the atopic dermatitis space.
Nektar Therapeutics’ investigational T cell stimulator rezpegaldesleukin eases symptom burden in patients with atopic dermatitis, according to a Tuesday readout from the Phase IIb REZOLVE-AD trial. The company’s stock surged as much as 175% on that afternoon, representing a vindication of sorts after former partner Eli Lilly turned its back on the drug (commonly called rezpeg) and Nektar in 2023.
Writing to investors on Tuesday, however, analysts at William Blair were more muted in their analysis, noting that rezpeg’s point of differentiation “remains unclear.” The drug performs about as well as other investigational treatments for atopic dermatitis, while falling “numerically lower” than Sanofi and Regeneron’s blockbuster drug Dupixent, the analysts wrote.
On the tolerability front, rezpeg also appears inferior to Dupixent, according to William Blair. “Given the chronic nature of atopic dermatitis, we believe the high frequencies . . . of injection site reactions versus Dupixent . . . could be a commercial liability for rezpeg,” the analysts contended. Such side effects were reported in 30% to 40% of rezpeg-treated patients, according to William Blair, whereas rates for Dupixent fell somewhere in the single to mid–double digit range.
“We believe there is an absence of clear differentiation in the highly competitive atopic dermatitis field,” William Blair wrote. Tuesday’s stock movement is likely more a “valuation normalization event” rather than investors “ascribing value to a differentiated asset,” the analysts explained. “Essentially, Nektar shares now trade around the company’s current cash levels.”
Tuesday’s readout comes from 16-week follow-up data from more than 390 patients enrolled in REZOLVE-AD. Participants were randomly assigned to receive one of three different rezpeg doses: 24 µg/kg every two weeks, 18 µg/kg every two weeks or 24 µg/kg every four weeks. Controls were given a placebo every two weeks.
Results showed that all three dose arms experienced improvements versus baseline in symptoms, as measured by scores on the Eczema Area and Severity Index (EASI). The effect was strongest in the highest-dose group, with a 61% reduction in EASI scores. Placebo comparators saw a 31% drop in scores. Rezpeg likewise hit several key secondary endpoints, including improvements in itch and body surface area affected.
Nektar CEO Howard Robin on Tuesday called rezpeg’s efficacy results “compelling,” noting that the biotech will file these data for presentation at a scientific congress later this year. Robin did not disclose regulatory plans for rezpeg.
Nektar was previously working on rezpeg in partnership with Eli Lilly, which in July 2017 paid $150 million upfront and promised up to $250 million in milestones for co-development and commercialization rights over the asset. Lilly pulled the plug on the partnership in April 2023 after releasing underwhelming Phase Ib data in September 2022.
The split appeared amicable at the time but soon turned sour. In August 2023, Nektar accused Lilly of incorrectly calculating rezpeg’s efficacy numbers. The biotech soon took the matter to the courts, suing its partner days later alleging breach of contract, negligent misrepresentation and unfair competition. That suit was still winding its way through the U.S. District Court in San Francisco as of June 12.
