Nektar Therapeutics still needs to establish what differentiates rezpeg from other atopic dermatitis therapies, according to analysts at William Blair.
Nektar Therapeutics continues to build the case for its T-cell stimulator rezpegaldesleukin in atopic dermatitis, with new Phase IIb data on Thursday suggesting that prolonged treatment leads to better improvements in symptom burden than seen in a previous readout.
Still, analysts at William Blair remain unconvinced. Nektar’s data drop, they wrote in a note to investors on Thursday, “does not materially alter our view on rezpeg in this setting as questions about rezpeg’s differentiation remain unanswered.”
These sentiments echo the firm’s previous assessment of Nektar’s initial readout from the mid-stage study, dubbed REZOLVE-AD. Released in June, these 16-week findings showed that rezpeg elicited a 61% drop in scores on the Eczema Area and Severity Index (EASI) inventory, a validated tool used to measure the severity of atopic dermatitis (AD) symptoms. EASI scores in the placebo arm decreased 31%.
William Blair, in an analysis written later in August, noted that rezpeg’s results fell “numerically lower” than the leading drug in the space, Sanofi and Regeneron’s blockbuster antibody Dupixent. Nektar’s candidate also resulted in a higher rate of injection-site reactions versus Dupixent, occurring in 30%-40% of patients taking rezpeg versus “in the high-single- to mid-double-digit percent range” for Dupixent, according to William Blair, which the analysts said “could be a commercial liability for rezpeg.”
Nektar’s follow-on data helps paint a better picture of rezpeg. After 32 weeks of treatment, according to the biotech’s news release, mean reduction in EASI score grew to 68% and improved further to 75% at 40 weeks. William Blair on Thursday described these results as “an even greater improvement” in symptom burden.
Nektar also noted in its Thursday release that rezpeg hit several key secondary endpoints in REZOLVE-AD, eliciting significant improvements in itch scores, quality of life, pain and sleep.
Safety remained a sticking point for William Blair, which aside from injection-site reactions also flagged rates of fever. Nektar on Thursday reported one case of pyrexia classified as a severe treatment-related adverse event. ”We believe that pyrexia could serve as an additional headwind for adoption of rezpeg in the clinical setting,” the analysts wrote.
Shares of Nektar jumped 15% at close of trading Thursday.
Rezpeg is an investigational T-cell stimulator that works by binding to the IL-2 receptor complex, in turn triggering the proliferation of regulatory T-cells. This mechanism allows the drug to correct immune dysregulation that otherwise drives AD and other autoimmune and inflammatory disorders. Nektar was previously advancing rezpeg in partnership with Eli Lilly under a 2017 contract. In April 2023, however, Lilly backed out of the deal following disappointing Phase Ib data.
Nektar in August 2023 sued Lilly, alleging that the latter incorrectly calculated rezpeg’s efficacy data. As of June 12, the case is still making its way through the San Francisco court system.
