EFFISAYIL ON: New Long-Term Data Released on Spesolimab Injection for GPP

New long-term findings from an ongoing open-label extension study assessing spesolimab-sbzo (Spevigo) in adults with generalized pustular psoriasis (GPP) have been released at the 2026 American Academy of Dermatology (AAD) Annual Meeting.1

These data, announced by LEO Pharma on March 27, may provide encouraging evidence suggesting this biologic drug can meaningfully diminish patients’ GPP flare burden over several years of use. The data were also commented on by trial investigator Arash Mostaghimi, MD, MPH, assistant professor of dermatology at Brigham & Women’s Hospital.

“Together these findings highlight the complementary roles of IV and SC [spesolimab] in the long-term management of GPP, supporting a treatment approach that helps address the full course of this chronic and unpredictable disease,” Mostaghimi said in a statement.1

GPP is characterized as a systemic, neutrophilic inflammatory skin condition marked by recurring, unpredictable flares resulting from chronic underlying disease activity. The disease can lead to substantial management challenges among patients given its heterogeneous clinical course and the potential severity of its acute exacerbations.1,2

The EFFISAYIL ON study is an open-label extension trial lasting 5 years and designed to look at the long-term efficacy, safety, and tolerability of subcutaneous (SC) spesolimab in individuals who had previously taken part in either the EFFISAYIL 1 or EFFISAYIL 2 pivotal studies. The preliminary data from this extension study suggests spesolimab may substantially curb patients’ flare frequency over time.1

Before entering the EFFISAYIL clinical program, those involved reported a mean flare rate of 2.0 per year. With long-term SC spesolimab treatment, the figure dipped to a cumulative mean of .13 flares per year. Among the 118 individuals treated with at least 3 years of spesolimab, nearly 75% were found by Mostaghimi et al to have remained completely flare-free throughout the period.

For the subset of subjects who did report flares during EFFISAYIL ON, intravenous (IV) spesolimab appeared to provide effective rescue therapy. Of the 131 total enrolled patients, 21 (16.0%) required IV spesolimab to manage 36 discrete flare events.1 At the first week, half of treated flares were shown to have attained a GPP Physician Global Assessment (GPPGA) pustulation subscore of 0 (clear), increasing to 58.3% by the second week. A GPPGA total score of 0 or 1 (suggesting clear or almost clear skin) was achieved in 41.7% of flare treatments at the first week and 55.6% at the second.

Additionally, the release by LEO Pharma suggests spesolimab’s preliminary safety profile is broadly consistent with what has previously been established for spesolimab.2 Among those included in the SC arm, 4.2% were found to have discontinued the drug due to adverse events (AEs). Among those in the IV arm, serious AEs were noted in 36.6%, with treatment cessation being attributed to AEs occurring in 4.6%.

Overall, these findings on long-term spesolimab injections for GPP were part of LEO Pharma's broader presence at AAD 2026. The data encompassed 17 accepted abstracts spanning the company's dermatology portfolio and pipeline.

References

1. LEO Pharma Announces New Long-Term Data for SPEVIGO® (spesolimab-sbzo) Injection in Adults with Generalized Pustular Psoriasis at AAD 2026. LEO Pharma. March 27, 2026. https://www.businesswire.com/news/home/20260327527368/en/LEO-Pharma-Announces-New-Long-Term-Data-for-SPEVIGO-spesolimab-sbzo-Injection-in-Adults-with-Generalized-Pustular-Psoriasis-at-AAD-2026.

2. Smith T. Subcutaneous Spesolimab Effective for Generalized Pustular Psoriasis Symptoms. HCPLive. March 18, 2025. Accessed March 27, 2026. https://www.hcplive.com/view/subcutaneous-spesolimab-effective-generalized-pustular-psoriasis-symptoms.