A Study to Assess Efficacy and Safety of Two Different Dose Regimens of Risankizumab Administered Subcutaneously in Japanese Subjects With Generalized Pustular Psoriasis or Erythrodermic Psoriasis

Inclusion Criteria: For GPP

• Have a diagnosis of GPP for at least 60 days prior to informed consent based on thediagnostic criteria of the Japanese Dermatological Association (JDA). Subjects notfulfilling one of the diagnostic criteria i.e., "accompanying systemic symptomsincluding fever or malaise" at the time of screening can be entered.
• Subjects with an erythema area with pustules accounting for ≥ 10% of the body surfacearea (BSA), and with a severity assessment criteria score (JDA total score) specifiedby the JDA of less than 14.
• Must be candidates for systemic therapy or phototherapy for GPP, as assessed by theinvestigator. For EP
• Have a diagnosis of EP prior to informed consent.
• Subjects with an inflammatory erythema area accounting for ≥ 80% of the BSA atscreening and at the time of the first administration of the study drug.
• Must be candidates for systemic therapy or phototherapy for EP, as assessed by theinvestigator.

Exclusion Criteria:

• Previous exposure to risankizumab.
• Currently enrolled in another investigational study or less than 30 days (fromscreening) since completing another investigational study (participation inobservational studies is permitted). For GPP
• Subjects with active ongoing inflammatory diseases other than GPP that might confoundtrial evaluations according to investigator's judgment. For EP
• Subjects with active ongoing inflammatory diseases other than EP that might confoundtrial evaluations according to investigator's judgment.
• Subject diagnosed with medication-induced or medication-exacerbated EP.