A Study to Test Whether BI 655130 (Spesolimab) Prevents Flare-ups in Patients With Generalized Pustular Psoriasis

This is a study in adolescents and adults with Generalized Pustular Psoriasis (GPP). People between 12 and 75 years old can take part in the study. The study is open to people who had GPP flare-ups in the past but whose skin is clear or almost clear when they join the study. The purpose of the study is to test 3 different doses of a medicine called spesolimab and to see whether it helps to prevent GPP flare-ups. Participants are put into 4 groups by chance. Three groups get different doses of spesolimab. The fourth group gets a placebo. Placebo looks like spesolimab but does not contain any medicine. Spesolimab and placebo are given as an injection under the skin. Participants are in the study for about 1 year and 4 months. During this time, they visit the study site about 15 times. For the first 11 months, participants get spesolimab or placebo injections every month. At the study visits, the doctors check participants' skin for signs of a new GPP flare-up. The doctors also check the general health of the participants. If a participant has a GPP flare-up during the study, more visits may be necessary. In case of a flare-up, participants get a dose of spesolimab as an infusion into a vein.