Efficacy and Safety of GLPG1205 in Subjects With Active Ulcerative Colitis

Inclusion Criteria: * Male or female subjects between 18 and 75 years * Documented history of UC * Presence of active UC for a minimum period of 14 days prior to screening and spread beyond the rectum, Mayo score ≥ 6 with rectal bleeding score ≥ 1 and endoscopy score ≥ 2 * Absence of infectious colitis * Tumor necrosis factor alpha (TNFα) inhibitor-naive subjects should have failed at least 1 prior conventional therapy * Continuation of concurrent treatment with oral steroids (≤30 mg prednisolone eq/day), immunosuppressants and 5-aminosalicylates at stable dose is allowed * Female subjects must have a negative blood pregnancy test, unless they are surgically sterile, had a hysterectomy, or have been postmenopausal for at least 1 year * Subjects will have to use highly effective contraceptive methods Exclusion Criteria: * History of sensitivity to any component of the study drug, or a history of drug or other allergy * Any concurrent illness, condition, disability, or clinically significant abnormality that, in the investigator's opinion, represents a safety risk for the subject's participation, may affect the interpretation of data, or may prevent the subject from safely completing the assessments * History of significant psychological, neurologic, hepatic, renal, endocrine, cardiovascular, GI (other than UC), pulmonary, or metabolic disease * History of active infections requiring intravenous antibiotics within the past 4 weeks prior to screening. * History of malignancy within the past 5 years; presence or history of intestinal malignancy * History of bowel surgery within 6 months prior to screening; history of colon resection with \< 30 cm of the colon remaining * Suspicion of Crohn's disease, indeterminate colitis, microscopic colitis, ischemic colitis, diverticular disease-associated colitis, or radiation-induced colitis * Subject who has received non-permitted UC therapies within specified timeframes, depending on the medication, as stated in the protocol * Subject who is pregnant or lactating