A Dose-finding and Confirmatory Trial of OPC-6535 in Patients With Active Crohn's Disease

Inclusion Criteria: * Primary lesion in either small intestine or large intestine * C-reactive protein (CRP) level above the upper limit of the normal range * Patients who have been receiving a 5-ASA formulation (oral mesalazine) at a fixed dose of 2.25 g/day or higher (not exceeding the approved dose) and at a fixed dosing regimen * Patients who have not received enteral nutrition or who have been receiving enteral nutrition at a fixed intake of 1200 kcal/day or less Exclusion Criteria: * Patients with an uncontrolled external fistula (including anal fistula) * Patients with a history of total proctocolectomy or subtotal colectomy * Patients with short bowel syndrome * Patients with an artificial anus * Patients with serious infectious disease (intra-abdominal abscess, etc) * Patients with malignant tumor * Female patients who are pregnant, lactating, or possibly pregnant, or who wish to become pregnant during the trial period