Study to Assess the Safety and Efficacy of Subcutaneously Injected Risankizumab in Adult Participants With Genital or Scalp Psoriasis

Psoriasis (PsO) is a chronic disease characterized by marked inflammation of the skin that results in thick, red, scaly plaques. This study will assess how safe and effective risankizumab is in adult participants with moderate to severe genital psoriasis or moderate to severe scalp psoriasis. Adverse events and change in disease signs and symptoms will be monitored. Risankizumab (Skyrizi) is a drug being studied for the treatment of moderate to severe genital psoriasis or moderate to severe scalp psoriasis. Approximately 200 participants with moderate to severe genital psoriasis or moderate to severe scalp psoriasis will be enrolled across approximately 45 sites globally. The study will be broken up into 2 studies by disease location, participants with moderate to severe genital psoriasis (Study-G) and moderate to severe scalp psoriasis (Study-S). In both studies participants will receive subcutaneous (SC) injections of risankizumab during the 52 week treatment period, or SC injections of placebo risankizumab during the 16 week treatment period followed by SC injections of risankizumab during the 36 week treatment period, with an 8-week follow-up period after the 52 week treatment period. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.