An Efficacy and Safety Study of Ontamalimab as Maintenance Therapy in Participants With Moderate to Severe Ulcerative Colitis

Remission: a composite score of participant reported symptoms using daily e-diary and centrally read endoscopy as follows: stool frequency sub-score 0 or 1 with at least a 1-point change from induction study baseline; and rectal bleeding sub-score of 0; and endoscopic sub-score 0 or 1 (modified, excludes friability). The composite score was a recommended measure consisted of Mayo score without the Physician global assessment (PGA) sub-score and ranges from 0-9 points. The Mayo score was a measure of UC disease activity ranged from 0-12 points and consisted of 4 sub-scores, each graded from 0-3 with higher scores indicating more severe disease. Sub-scores were rectal bleeding (range: 0-3, where 0= no blood & 3=blood alone passes), stool frequency (range: 0-3, where 0= normal number of stools and 3=at least 5 stools more than normal), PGA sub-score (range: 0-3- higher score= severe disease), and an endoscopic sub-score (range: 0-3, where 0= normal/inactive disease; 3= severe disease).

Endoscopic remission was defined by centrally read endoscopic sub-score 0 or 1 (modified, excludes friability). The centrally read endoscopic sub-score of mayo score ranged from 0 to 3, where 0=normal or inactive disease; 3=severe disease (spontaneous bleeding, ulceration).

Clinical remission was defined by stool frequency sub-score of 0 or 1 with at least a 1-point change from induction study baseline in stool frequency sub-score, and rectal bleeding sub-score of 0. Rectal bleeding was assessed on a scale from 0-3, where 0: no blood seen, 1: streaks of blood with stool less than half time, 2: obvious blood or streaks of blood with stool most of the time, and 3: blood alone passes. Stool frequency was assessed on a scale from 0-3, where 0: normal number of stools for this participant, 1: 1 to 2 stools more than normal; 2: 3 to 4 stools more than normal, and 3: 5 or more stools more than normal. Higher scores indicated more severe disease.

Sustained remission was defined as in remission at Week 52 visit, among participants who were in remission at the time of baseline. Remission was defined as a stool frequency sub-score of 0 or 1 with at least a 1-point change from induction study baseline in stool frequency sub-score and rectal bleeding sub-score of 0 and endoscopic sub-score of 0 or 1 (modified, excludes friability). Sub-scores were rectal bleeding (range: 0-3, where 0= no blood & 3=blood alone passes), stool frequency (range: 0-3, where 0= normal number of stools and 3=at least 5 stools more than normal), and an endoscopic sub-score (range: 0-3, where 0= normal/inactive disease; 3= severe disease).

Clinical response was defined as a decrease from induction study baseline in the composite score of subject reported symptoms using daily e-diary and centrally read endoscopy of at least 2 points and at least 30%, with an accompanying decrease in the sub-score for rectal bleeding >=1 point or a sub-score for rectal bleeding <= 1. Composite score consisted of Mayo score without the PGA sub-score and ranges from 0 to 9 points. Mayo score was a measure of UC disease activity, ranged from 0 -12 points and consisted of 4 sub-scores, each graded from 0 -3, higher scores indicating more severe disease. The rectal bleeding sub-scores ranges from 0-3, where 0= no blood & 3=blood alone passes and centrally read endoscopic sub-score ranges from 0-3, where 0= normal/inactive disease; 3= severe disease.

Mucosal healing was defined by centrally read endoscopic sub-score 0 or 1 (modified, excludes friability) and centrally read Geboes score of <=2. The centrally read endoscopic sub-score of mayo score ranges from 0 to 3 with higher scores indicating more severe disease. Geboes score grading system, was a validated score for evaluating histologic disease activity in UC as follows: grade 0 = structural and architectural changes; grade 1 = chronic inflammatory infiltrate; grade 2 = lamina propria neutrophils and eosinophils; grade 3 = neutrophils in the epithelium; grade 4 = crypt destruction; grade 5 = erosions or ulceration. A higher Geboes score indicates more severe disease.

Glucocorticoid-free clinical remission was defined as clinical remission in addition to not requiring any treatment with glucocorticoids for at least 4 weeks prior to the Week 52 visit among participants using glucocorticoids at the baseline. Clinical remission was defined as stool frequency sub-score of 0 or 1 with at least a 1-point change from induction study baseline in stool frequency sub-score, and rectal bleeding sub-score of 0, at the Week 52 visit. The stool frequency sub-score ranges from 0-3, where 0= normal number of stools and 3=at least 5 stools more than normal and rectal bleeding sub-score ranges from 0-3, where 0= no blood & 3=blood alone passes).

Glucocorticoid-free remission was defined as remission in addition to not requiring any treatment with glucocorticoids for at least 4 weeks prior to the Week 52 visit, among participants using glucocorticoids at the baseline. Remission was defined as a composite score of participant-reported symptoms using daily e-diary and endoscopy, with stool frequency sub-score of 0 or 1 with at least a 1-point change from induction study baseline, and rectal bleeding sub-score of 0, and endoscopic sub-score of 0 or 1 (modified, excludes friability). The composite score was a recommended measure consisting of the Mayo score without the PGA sub-score and ranges from 0 to 9 points. The stool frequency sub-score, rectal bleeding sub-score and endoscopic sub-score of mayo score ranges from 0 to 3 with higher scores indicating more severe disease.

Remission defined as a total mayo score of less than or equal to (<=) 2 with no individual sub-score (stool frequency, rectal bleeding, endoscopy [modified, excludes friability], and physician's global assessment) exceeding 1. The total mayo score ranges from 0 to 12 points and consisted of the following 4 sub-scores, each graded from 0 to 3 with higher scores indicating more severe disease: Sub-scores were rectal bleeding (range: 0 to 3, where 0=no blood seen and 3=blood alone passes), stool frequency (range: 0 to 3, where 0=normal number of stools and 3=at least 5 stools more than normal), PGA sub-score (range: 0 to 3-higher score indicating the severe disease), and an endoscopic sub-score (range: 0 to 3, where 0=normal or inactive disease; 3=severe disease [spontaneous bleeding, ulceration].

Clinical remission was defined as both rectal bleeding and stool frequency sub-scores of 0. Rectal bleeding was assessed on a scale from 0-3, where 0: no blood seen, 1: streaks of blood with stool less than half time, 2: obvious blood or streaks of blood with stool most of the time, and 3: blood alone passes. Stool frequency was assessed on a scale from 0-3, where 0: normal number of stools for this participant, 1: 1 to 2 stools more than normal, 2: 3 to 4 stools more than normal, and 3: 5 or more stools more than normal. Higher scores indicated more severe disease.

Sustained endoscopic remission was defined as in endoscopic remission at Week 52 visit among participants who were in endoscopic remission at the time of baseline. Endoscopic remission was defined as a centrally read endoscopic sub-score of 0 or 1 (modified, excludes friability). The centrally read endoscopic sub-score range from 0 to 3, where 0=normal or inactive disease; 3=severe disease.

An adverse event (AE) was any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. TEAEs are defined as AEs with start dates at the time of or following the first exposure to investigational product. Number of participants with TEAEs were reported.

Antibody testing was conducted using an electro chemiluminescent signal method. Serum samples was analyzed for presence of antidrug antibodies to ontamalimab. Number of participants who developed positive results for ontamalimab were reported.