OBJECTIVE: The aim of the study was to describe the characteristics and outcomes of GPP flares using historical medical information from patients enrolled in the Effisayil™ 1 trial.

METHODS: Investigators collected retrospective medical data characterizing patients' GPP flares prior to clinical trial enrollment. Data on overall historical flares were collected, as well as information on patients' typical, most severe, and longest past flares. This included data on systemic symptoms, flare duration, treatment, hospitalization, and time to clearance of skin lesions.

RESULTS: In this cohort (N = 53), patients with GPP experienced a mean of 3.4 flares per year. Flares were painful, associated with systemic symptoms, and often triggered by stress, infections, or treatment withdrawal. Resolution of flares was longer than 3 weeks in 57.1%, 71.0%, and 85.7% of documented (or identified) typical, most severe, and longest flares, respectively. GPP flares led to patient hospitalization in 35.1%, 74.2%, and 64.3% of patients for their typical, most severe, and longest flares, respectively. For the majority of patients, pustules took up to 2 weeks to clear for a typical flare and 3-8 weeks to clear for the most severe and longest flares.

METHODS AND ANALYSIS: At least 51 patients with an acute GPP flare will be randomised 2:1 to receive a single 900 mg intravenous dose of spesolimab or placebo and followed for up to 28 weeks. The primary endpoint is a Generalized Pustular Psoriasis Physician Global Assessment (GPPGA) pustulation subscore of 0 (pustule clearance) at Week 1. The key secondary endpoint is a GPPGA score of 0 or 1 (clear or almost clear) at Week 1. Safety will be assessed over the study duration by the occurrence of treatment-emergent adverse events. Blood and skin biopsies will be collected to assess biomarkers. Superiority of spesolimab over placebo in the proportion of patients achieving the primary and key secondary endpoints will be evaluated.

ETHICS AND DISSEMINATION: The study complies with the ethical principles of the Declaration of Helsinki, the International Council for Harmonisation's Good Clinical Practice and local regulations. Ethics committee approvals have been obtained for each centre from all participating countries and are listed in online supplementary file 1. Primary results will be published in a peer-reviewed journal.

METHODS: Patients will have a documented history of GPP with a Generalized Pustular Psoriasis Physician Global Assessment (GPPGA) score of 0 or 1 (clear or almost clear) at screening and randomization. Patients will be randomized 1:1:1:1 to three groups receiving a 600-mg subcutaneous loading dose of spesolimab followed by a 300-mg maintenance dose administered every 4 or 12 weeks, or a 300-mg loading dose followed by a 150-mg maintenance dose administered every 12 weeks, and one group receiving placebo, for 48 weeks. The primary endpoint is time to first GPP flare. If a patient experiences a GPP flare during the randomized maintenance treatment period, an open-label intravenous dose of 900-mg spesolimab will be administered, with an option for a second intravenous dose after 1 week.

CONCLUSIONS: Effisayil™ 2 is the first placebo-controlled study in patients with GPP to investigate whether maintenance treatment with spesolimab can prevent flares and provide sustained disease control. This study will provide valuable insights on the long-term management of patients with this potentially life-threatening skin disease.

METHODS: In a phase 2 trial, we randomly assigned patients with a GPP flare in a 2:1 ratio to receive a single 900-mg intravenous dose of spesolimab or placebo. Patients in both groups could receive an open-label dose of spesolimab on day 8, an open-label dose of spesolimab as a rescue medication after day 8, or both and were followed to week 12. The primary end point was a Generalized Pustular Psoriasis Physician Global Assessment (GPPGA) pustulation subscore of 0 (range, 0 [no visible pustules] to 4 [severe pustulation]) at the end of week 1. The key secondary end point was a GPPGA total score of 0 or 1 (clear or almost clear skin) at the end of week 1; scores range from 0 to 4, with higher scores indicating greater disease severity.

RESULTS: A total of 53 patients were enrolled: 35 were assigned to receive spesolimab and 18 to receive placebo. At baseline, 46% of the patients in the spesolimab group and 39% of those in the placebo group had a GPPGA pustulation subscore of 3, and 37% and 33%, respectively, had a pustulation subscore of 4. At the end of week 1, a total of 19 of 35 patients (54%) in the spesolimab group had a pustulation subscore of 0, as compared with 1 of 18 patients (6%) in the placebo group (difference, 49 percentage points; 95% confidence interval [CI], 21 to 67; P<0.001). A total of 15 of 35 patients (43%) had a GPPGA total score of 0 or 1, as compared with 2 of 18 patients (11%) in the placebo group (difference, 32 percentage points; 95% CI, 2 to 53; P = 0.02). Drug reactions were reported in 2 patients who received spesolimab, in 1 of them concurrently with a drug-induced hepatic injury. Among patients assigned to the spesolimab group, infections occurred in 6 of 35 (17%) through the first week; among patients who received spesolimab at any time in the trial, infections had occurred in 24 of 51 (47%) at week 12. Antidrug antibodies were detected in 23 of 50 patients (46%) who received at least one dose of spesolimab.

OBJECTIVE: To develop an international consensus definition and diagnostic criteria for GPP using the modified Delphi method.

EVIDENCE REVIEW: The rarity of GPP presents a challenge in acquiring comprehensive published clinical data necessary for developing standardized definition and criteria. Instead of relying on a literature search, 43 statements that comprehensively addressed the fundamental aspects of the definitions and diagnostic criteria for GPP were formulated based on expert reviews of 64 challenging GPP cases. These statements were presented to a panel of 33 global GPP experts for voting, discussion, and refinements in 2 virtual consensus meetings. Consensus during voting was defined as at least 80% agreement; the definition and diagnostic criteria were accepted by all panelists after voting and in-depth discussion.

FINDINGS: In the first and second modified Delphi round, 30 (91%) and 25 (76%) experts participated. In the initial Delphi round, consensus was achieved for 53% of the statements, leading to the approval of 23 statements that were utilized to develop the proposed definitions and diagnostic criteria for GPP. During the second Delphi round, the final definition established was, "Generalized Pustular Psoriasis is a systemic inflammatory disease characterized by cutaneous erythema and macroscopically visible sterile pustules." It can occur with or without systemic symptoms, other psoriasis types, and laboratory abnormalities. GPP may manifest as an acute form with widespread pustules or a subacute variant with an annular phenotype. The identified essential criterion was, "Macroscopically visible sterile pustules on erythematous base and not restricted to the acral region or within psoriatic plaques."