['psoriasis']
['risankizumab', 'ustekinumab', 'placebo for risankizumab', 'placebo for ustekinumab']

        Inclusion criteria:

          -  Male or female patients. Women of childbearing potential* must be ready and able to
             use highly effective methods of birth control per International Council on
             Harmonisation (ICH) M3(R2) that result in a low failure rate of less than 1% per year
             when used consistently and correctly. A list of contraception methods meeting these
             criteria is provided in the patient information.

             *Women of childbearing potential are defined as:

               -  having experienced menarche and are

               -  not postmenopausal (12 months with no menses without an alternative medical
                  cause) and are

               -  not permanently sterilized (e.g., tubal occlusion, hysterectomy, bilateral
                  oophorectomy or bilateral salpingectomy).

          -  Age ≥ 18 years at screening

          -  Have a diagnosis of chronic plaque psoriasis (with or without psoriatic arthritis) for
             at least 6 months before the first administration of study drug.Duration of diagnosis
             may be reported by the patient,

          -  Have stable moderate to severe chronic plaque psoriasis with or without psoriatic
             arthritis at both Screening and Baseline (Randomization):

               1. Have an involved body surface area (BSA) ≥ 10% and

               2. Have a Psoriasis Area and Severity Index (PASI) score ≥ 12 and

               3. Have a static Physician Global Assessment (sPGA) score of ≥ 3.

          -  Must be candidates for systemic therapy or phototherapy for psoriasis treatment, as
             assessed by the investigator

          -  Must be a candidate for treatment with Stelara® (ustekinumab) according to local
             label.

          -  Signed and dated written informed consent prior to admission to the study in
             accordance with Good Clinical Practices (GCP) and local legislation

        Exclusion criteria:

          -  Patients with:

               1. non-plaque forms of psoriasis (including guttate, erythrodermic, or pustular),

               2. current drug-induced psoriasis (including an exacerbation of psoriasis from beta
                  blockers, calcium channel blockers, or lithium),

               3. active ongoing inflammatory diseases other than psoriasis and psoriatic arthritis
                  that might confound trial evaluations according to investigator's judgment,

          -  Previous exposure to BI 655066,

          -  Currently enrolled in another investigational study or less than 30 days (from
             screening) since completing another investigational study (participation in
             observational studies is permitted),

          -  Previous exposure to ustekinumab (Stelara®),

          -  Use of any restricted medication, or any drug considered likely to interfere with the
             safe conduct of the study,

          -  Major surgery performed within 12 weeks prior to randomization or planned within 12
             months after screening (e.g., hip replacement, aneurysm removal, stomach ligation),

          -  Known chronic or relevant acute infections including active tuberculosis, HIV or viral
             hepatitis; QuantiFERON® tuberculosis (TB) test or purified protein derivative (PPD)
             skin test will be performed according to local labelling for comparator products. If
             the result is positive, patients may participate in the study if further work up
             (according to local practice/guidelines) establishes conclusively that the patient has
             no evidence of active tuberculosis. If presence of latent tuberculosis is established,
             then treatment should have been initiated and maintained according to local country
             guidelines,

          -  Any documented active or suspected malignancy or history of malignancy within 5 years
             prior to screening, except appropriately treated basal or squamous cell carcinoma of
             the skin or in situ carcinoma of uterine cervix,

          -  Evidence of a current or previous disease, medical condition (including chronic
             alcohol or drug abuse) other than psoriasis, surgical procedure (i.e., organ
             transplant), medical examination finding (including vital signs and electrocardiogram
             [ECG]), or laboratory value at the screening visit outside the reference range that is
             in the opinion of the investigator, is clinically significant and would make the study
             participant unreliable to adhere to the protocol or to complete the trial, compromise
             the safety of the patient, or compromise the quality of the data,

          -  History of allergy/hypersensitivity to a systemically administered biologic agent or
             its excipients,

          -  Women who is pregnant, nursing, or who plans to become pregnant while in the trial,

          -  Previous enrolment in this trial.
      