An Open-Label, Multi-Center Trial in the Treatment of Subjects With Moderate to Severe Plaque Type Psoriasis

Inclusion Criteria: * Male or female of non-childbearing potential (at least 2 years post-menopausal or undergone successful surgical sterilization at least 1 year before inclusion) * Presence of moderate to severe plaque psoriasis with a PASI of at least 5 Exclusion Criteria: * Pustular, guttate or other non-plaque forms of psoriasis or psoriatic arthritis * Significant coexisting hepatic, renal, or bone marrow disease, hyperlipidemia, chronic pancreatitis, osteoporosis, or a history indicating adrenal cortex dysfunction or any other serious disease (including cancer and subjects known to be HIV positive) * History of heart failure, myocardial infarction within the past six months, cardiac arrhythmia, or under treatment for heart disorders * Clinically significant abnormal ECG-intervals or morphology of the ECG; QT or QTc \>470 ms in females or \>450 ms in males * Use of vitamin A (\>1000 µg/day), phenytoin, carbamazepine, warfarin, rifampicin, tetracyclines, ketoconazole, itraconazole, astemizole, terfenadine, cisapride, anti-psychotics, anti-depressants, lithium, antimalarials, alpha-blocking drugs, angiotensin-converting enzyme inhibitors, cyclosporin A, glucocorticosteroids and non-steroidal anti-inflammatory drugs, non-potassium-sparing diuretics * Previous use of any systemic immunomodulatory therapy (biologicals) or psoriasis vaccine * Use of other systemic therapy for psoriasis (e.g. PUVA, systemic steroids, cyclosporin A, methotrexate, retinoids) within four weeks prior to Visit 2 * Use of UV therapy or excessive UV exposure or topical therapy for psoriasis other than bland emollients within two weeks prior to Visit 2