Nektar's REZOLVE-AD Phase IIb study of rezpegaldesleukin (rezpeg) in moderate-to-severe eczema patients met its primary endpoint, with all three dose arms showing statistically significant improvements over baseline at 16 weeks as measured by the Eczema Area and Severity Index (EASI)213.
The highest rezpeg dose achieved a 61% reduction in EASI score compared to baseline, while the placebo group saw a 31% reduction, resulting in a 30% placebo-adjusted improvement for the high-dose group235.
Rezpeg also met several key secondary endpoints, including improvements in itch and body surface area affected by eczema2.
Rezpeg works by stimulating regulatory T cells via the interleukin-2 (IL-2) receptor, offering a different mechanism from established eczema biologics like Sanofi/Regeneron's Dupixent, which blocks the IL-13 and IL-4 pathways5.
Despite these encouraging results, analysts remain unconvinced due to the competitive landscape—Dupixent has already achieved strong efficacy (about a 50% placebo-adjusted reduction in comparable trials) and widespread market adoption5.
Nektar’s partnership with Eli Lilly for rezpeg ended in 2023 after underwhelming Phase Ib results, and a legal dispute with Lilly currently complicates Nektar’s path forward24.
Following the results announcement, Nektar’s stock price surged, but the long-term outlook for rezpeg’s commercial viability remains uncertain given market competition and regulatory questions345.
Sources:
1. https://ir.nektar.com/news-releases/news-release-details/rezolve-ad-phase-2b-study-rezpegaldesleukin-meets-primary-and
2. https://www.biospace.com/drug-development/nektar-declares-phase-iib-eczema-win-for-rezpeg-but-analysts-unconvinced
3. https://www.fiercebiotech.com/biotech/investors-sweet-nektar-phase-2b-eczema-success-doubles-share-price
4. https://www.drugdiscoverytrends.com/nektars-phase-2b-win-triggers-surge-but-legal-tussle-with-lilly-complicates-path-forward/
5. https://medcitynews.com/2025/06/nektar-atopic-dermatitis-eczema-inflammation-immunology-rezpeg-treg-dupixent-nktr/