Clinical response is defined as a decrease from baseline in the total Mayo score of at least 3 points and at least 30%, accompanied by a decrease in the subscore for rectal bleeding of at least 1 point or an absolute subscore of 1 or less. Baseline was defined as the score collected during the screening period. The Mayo Score/Disease Activity Index (DAI) measures disease activity through assessment of 4 items: stool frequency, rectal bleeding, endoscopy findings, and Physician Global Assessment (PGA). Each item of the score is assessed on a 4-point scale, 0, 1, 2, or 3, with a higher score representing greater severity. In this study, the endoscopy subscore was expanded to a 5-point scale to increase sensitivity in this important dimension of the disease (0=normal/inactive disease, 4=deep ulceration). The Total Mayo Score can therefore range from 0 to13 points.