The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. A clinical response is defined as a reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with an accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point.

All participants who were randomized and received at least one infusion of study medication (Intent To Treat Population, ITT) were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. A clinical response is defined as a reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with an accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Mucosal healing was defined as endoscopic subscore ≤ 1 point

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. A clinical response is defined as a reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with an accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Inflammatory Bowel Disease Questionnaire (IBDQ) was used to measure disease specific quality of life. The IBDQ consists of a self-administered 32-item questionnaire that evaluates quality of life across 4 dimensional scores: Bowel, Systemic, Social and Emotional. The response to each question can range from 1 to 7, with 1 indicating severe problem and 7 indicating normal health. The total IBDQ is computed as the sum of the responses to the individual IBDQ questions. The total score can range between 32 to 224 with higher scores indicating a better quality of life.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

The Inflammatory Bowel Disease Questionnaire (IBDQ) was used to measure disease specific quality of life. The IBDQ consists of a self-administered 32-item questionnaire that evaluates quality of life across 4 dimensional scores: Bowel, Systemic, Social and Emotional. The response to each question can range from 1 to 7, with 1 indicating severe problem and 7 indicating normal health. The total IBDQ is computed as the sum of the responses to the individual IBDQ questions. The total score can range between 32 to 224 with higher scores indicating a better quality of life.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute rectal bleeding subscore of ≤1 point was indicative of mild disease.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute stool frequency subscore of ≤1 point was indicative of mild disease.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute PGA subscore of ≤1 point was indicative of mild disease.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical response=reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point. Inadequate response/intolerance=inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

All participants in ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing. Prior inadequate response/intolerance was to an approved anti-TNF agent at an approved labeled dose for ≥8 weeks.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical response=reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point. Inadequate response/intolerance=inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

All participants in ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing. Prior inadequate response/intolerance was to an approved anti-TNF agent at an approved labeled dose for ≥8 weeks.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. A clinical response is defined as a reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with an accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point. Inadequate response/intolerance

=inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

All participants in ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing. Prior inadequate response/intolerance was to an approved anti-TNF agent at an approved labeled dose for ≥8 weeks.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. Related AE=relationship of certain, probable, possible, or missing. SAE=any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, results in development of drug dependency or drug abuse, is an important medical event.

All participants who received at least 1 infusion of open-label study medication at any time were included in the safety analyses of the Open-Label Extension phase.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. AEs of special interest are those AEs that may be associated with the use of immunomodulatory drugs, including all infections, serious infections, and opportunistic infections; autoimmune disorders; neoplasms; acute infusional AEs (pre-specified AEs occurring within 1 hour of start of infusion) and peri-infusional AEs (pre-specified AEs occurring within 24 hours of the start of infusion).

All participants who received at least 1 infusion of open-label study medication at any time were included in the safety analyses of the Open-Label Extension phase.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Mucosal healing was defined as endoscopic subscore ≤ 1 point. Inadequate response/intolerance = inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

All participants in ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing. Prior inadequate response/intolerance was to an approved anti-TNF agent at an approved labeled dose for ≥8 weeks.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. Related AE=relationship of certain, probable, possible, or missing. SAE=any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, results in development of drug dependency or drug abuse, is an important medical event.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. AEs of special interest are those AEs that may be associated with the use of immunomodulatory drugs, including all infections, serious infections, and opportunistic infections; autoimmune disorders; neoplasms; acute infusional AEs (pre-specified AEs occurring within 1 hour of start of infusion) and peri-infusional AEs (pre-specified AEs occurring within 24 hours of the start of infusion).

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Complete physical examination was obtained at the Screening Visit, Day MP-365, and OL Final Visit/Early Termination visits. Interim physical examinations were performed at other study visits. Interim physical exam were not as comprehensive as the initial full examination but did note any changes in the participant's condition since the last assessment and did not preclude examination of any of the body systems as clinically indicated. Participants were observed for AEs and vital signs (blood pressure, heart rate, and temperature).

As the results of this study were presented in a synoptic report, physical examination evaluations were not summarized. Laboratory abnormalities and vital signs were collected and summarized.

High=greater than Upper Normal Limit (ULN), Low=lower than Lower Normal Limit (LLN). LLN/ULN= Hemoglobin (HGB): >3 g/dL decrease from Baseline (BL); Hematocrit: <0.75 x BL; Erythrocytes: <0.75 x BL; Platelets (PLT): <0.67 x LLN/>1.5 x ULN; Leukocytes: <0.75 x LLN/ >1.25 x ULN; neutrophils+bands: <1.0 x 10^3 c/uL; eosinophils: >0.750 x 10^3 c/uL; monocytes: >2000 mm3; lymphocytes: <0.750 x 10^3 c/uL/ >7.50 x 10^3 c/uL.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= Alkaline phosphatase (ALP): >2 x ULN; aspartate aminotransferase (AST): >3 x ULN; alanine aminotransferase (ALT): >3 x ULN; G-Glutamyl transferase (GGT): >2 x ULN; Bilirubin: >2 x ULN; blood urea nitrogen (BUN): >2 x BL; creatinine: >4 x BL; Sodium (Na): <0.95 x LLN/ >1.05 x ULN; potassium (K): <0.9 x LLN/ >1.1 x ULN; calcium (Ca): <0.8 x LLN/>1.2 x ULN; phosphorous (P): <0.75 x LLN/ >1.2 5 x ULN

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= serum glucose (Glu): <65 mg/dL/ >220 mg/dL; total protein: < 0.9 x LLN/ >1.1 x ULN; albumin:<0.9 x LLN; uric acid: >1.5 x ULN. For Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]): Use ≥2 when BL value missing or value ≥4, or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

High=greater than Upper Normal Limit (ULN), Low=lower than Lower Normal Limit (LLN). LLN/ULN= Hemoglobin (HGB): >3 g/dL decrease from Baseline (BL); Hematocrit: <0.75 x BL; Erythrocytes: <0.75 x BL; Platelets (PLT): <0.67 x LLN/>1.5 x ULN; Leukocytes: <0.75 x LLN/ >1.25 x ULN; eosinophils: >0.750 x 10^3 c/uL; monocytes: >2000 mm3; lymphocytes: <0.750 x 10^3 c/uL/ >7.50 x 10^3 c/uL; blood urea nitrogen (BUN): >2 x BL; creatinine: >4 x BL; Sodium (Na): <0.95 x LLN/ >1.05 x ULN; potassium (K): <0.9 x LLN/ >1.1 x ULN; phosphorous (P): <0.75 x LLN/ >1.2 5 x ULN;

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= serum glucose (Glu): <65 mg/dL/ >220 mg/dL; total protein: < 0.9 x LLN/ >1.1 x ULN; albumin:<0.9 x LLN. For Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]): Use ≥2 when BL value missing or value ≥4, or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

A electrochemiluminescent immunoassay screened sera for drug-specific antibodies, immunocompetition was used to identify specific anti-Abatacept reactivity. CTLA4 and Possibly Ig category=reactivity against extracellular domain of human CTLA4, constant regions of human IgG1, or both (CTLA4Ig; Abatacept molecule). Ig and/or Junction category=reactivity against constant regions and/or hinge region of human IgG1. Drug-induced seropositivity was defined as a post-baseline titer higher than Baseline, or any post-baseline positivity if Baseline value was missing.

All subjects with at least one post-baseline immunogenicity measurement during the study period were included in the immunogenicity data set. "Positive" was defined as "positive post-baseline IP-1" and with a titer value greater than the baseline titer value. Participants with missing baseline titer were assumed "negative" at baseline.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Mucosal healing was defined as endoscopic subscore ≤ 1 point

All participants in the ITT Population were included in the efficacy analyses. Participants with missing Mayo score were defined as not having achieved clinical response, remission, or mucosal healing.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis to determine the percentage of participants in clinical remission at both Month 6 and Month 12 was not conducted for the MP as planned.

Baseline corticosteroids equivalent of ≤30 mg prednisone daily. The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater frequency or severity. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analyses for corticosteroid sparing were not conducted for the MP as planned.

The Inflammatory Bowel Disease Questionnaire (IBDQ) was used to measure disease specific quality of life. The IBDQ consists of a self-administered 32-item questionnaire that evaluates quality of life across 4 dimensional scores: Bowel, Systemic, Social and Emotional. The response to each question can range from 1 to 7, with 1 indicating severe problem and 7 indicating normal health. The total IBDQ is computed as the sum of the responses to the individual IBDQ questions. The total score can range between 32 to 224 with higher scores indicating a better quality of life.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis for changes from baseline in IBDQ responses were not conducted for the MP as planned.

The SF-36 is a validated instrument to measure health-related quality of life across multiple disease states. Individual subscale scores and 2 summary scores are calculated: (1) physical component summary (PCS) which includes physical functioning, role-physical, bodily pain, and general health; (2) mental component summary (MCS) which includes vitality, social functioning, role-emotional, and mental health. Each scale is directly transformed into a 0-100 scale on the assumption that each question carries equal weight, with values ranging from worse health (0) to best health (100).

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis for changes from baseline in SF-36 responses were not conducted for the MP as planned.

Baseline corticosteroids equivalent of ≤30 mg prednisone daily. The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater frequency or severity. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analyses for corticosteroid sparing were not conducted for the MP as planned.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute rectal bleeding subscore of ≤1 point was indicative of mild disease.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis to determine the percentage of participants with rectal subscores indicating mild disease (≤1) was not conducted for the MP as planned.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute stool frequency subscore of ≤1 point was indicative of mild disease.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis to determine the percentage of participants with stool frequency subscores indicating mild disease (≤1) was not conducted for the MP as planned.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. An absolute PGA subscore of ≤1 point was indicative of mild disease.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary endpoint analysis to determine the percentage of participants with PGA subscores indicating mild disease (≤1) was not conducted for the MP as planned.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical response=reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point. Inadequate response/intolerance=inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of clinical response in subjects who have had an inadequate response and/or intolerance to anti-TNF therapy was not conducted for the MP as planned.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point. Inadequate response/intolerance =inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of clinical remission in subjects who have had an inadequate response and/or intolerance to anti-TNF therapy was not conducted for the MP as planned.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Mucosal healing was defined as endoscopic subscore ≤1 point. Inadequate response/intolerance = inadequate response/intolerance to an approved anti-TNF agent prior to this study at an approved labeled dose for ≥8 weeks.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of mucosal healing in subjects who have had an inadequate response and/or intolerance to anti-TNF therapy was not conducted for the MP as planned.

A electrochemiluminescent immunoassay screened sera for drug-specific antibodies, immunocompetition was used to identify specific anti-Abatacept reactivity. CTLA4 and Possibly Ig category=reactivity against extracellular domain of human CTLA4, constant regions of human IgG1, or both (CTLA4Ig; Abatacept molecule). Ig and/or Junction category=reactivity against constant regions and/or hinge region of human IgG1. Drug-induced seropositivity was defined as a post-baseline titer higher than Baseline, or any post-baseline positivity if Baseline value was missing.

All subjects with at least one post-baseline immunogenicity measurement during the study period were included in the immunogenicity data set. "Positive" was defined as "positive post-baseline IP-1" and with a titer value greater than the baseline titer value. Participants with missing baseline titer were assumed "negative" at baseline.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. Related AE=relationship of certain, probable, possible, or missing. SAE=any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, results in development of drug dependency or drug abuse, is an important medical event.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. AEs of special interest are those AEs that may be associated with the use of immunomodulatory drugs, including all infections, serious infections, and opportunistic infections; autoimmune disorders; neoplasms; acute infusional AEs (pre-specified AEs occurring within 1 hour of start of infusion) and peri-infusional AEs (pre-specified AEs occurring within 24 hours of the start of infusion).

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Complete physical examination was obtained at the Screening Visit, Day MP-365, and OL Final Visit/Early Termination visits. Interim physical examinations were performed at other study visits. Interim physical exam were not as comprehensive as the initial full examination but did note any changes in the participant's condition since the last assessment and did not preclude examination of any of the body systems as clinically indicated. Participants were observed for AEs and vital signs (blood pressure, heart rate, and temperature).

As the results of this study were presented in a synoptic report, physical examination evaluations were not summarized. Laboratory abnormalities and vital signs were collected and summarized.

High=greater than ULN, Low=lower than LLN. LLN/ULN= HGB: >3 g/dL decrease from Baseline (BL); Hematocrit: <0.75 x BL; Erythrocytes: <0.75 x BL; PLT: <0.67 x LLN/>1.5 x ULN; Leukocytes: <0.75 x LLN/ >1.25 x ULN; neutrophils+bands: <1.0 x 10^3 c/uL; eosinophils: >0.750 x 10^3 c/uL; monocytes: >2000 mm3; lymphocytes: <0.750 x 10^3 c/uL/ >7.50 x 10^3 c/uL; GGT: >2 x ULN; Bilirubin: >2 x ULN; BUN: >2 x BL; Na: <0.95 x LLN/ >1.05 x ULN; K: <0.9 x LLN/ >1.1 x ULN; Ca: <0.8 x LLN/>1.2 x ULN

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= serum glucose (Glu): <65 mg/dL/ >220 mg/dL; fasting serum Glu: <0.8 x LLN/ >1.5 x ULN; total protein: < 0.9 x LLN/ >1.1 x ULN; albumin:<0.9 x LLN; uric acid: >1.5 x ULN. For Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]): Use ≥2 when BL value missing or value ≥4, or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Complete physical examination was obtained at the Screening Visit, Day MP-365, and OL Final Visit/Early Termination visits. Interim physical examinations were performed at other study visits. Interim physical exam were not as comprehensive as the initial full examination but did note any changes in the participant's condition since the last assessment and did not preclude examination of any of the body systems as clinically indicated. Participants were observed for AEs and vital signs (blood pressure, heart rate, and temperature).

As the results of this study were presented in a synoptic report, physical examination evaluations were not summarized. Laboratory abnormalities and vital signs were collected and summarized.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. A clinical response is defined as a reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with an accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point.

All participants who received at least 1 infusion of open-label study medication at any time were included in the efficacy analyses of the OL. Number of Participants Analyzed=all participants in OL; n=number of evaluable participants.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Clinical remission is defined as a Mayo score of ≤ 2 points with no individual subscore exceeding 1 point.

All participants who received at least 1 infusion of open-label study medication at any time were included in the efficacy analyses of the OL. Number of Participants Analyzed=all participants in OL; n=number of evaluable participants.

High=greater than Upper Normal Limit (ULN), Low=lower than Lower Normal Limit (LLN). LLN/ULN= Hemoglobin (HGB): >3 g/dL decrease from Baseline (BL); Hematocrit: <0.75 x BL; Erythrocytes: <0.75 x BL; Platelets (PLT): <0.67 x LLN/>1.5 x ULN; Leukocytes: <0.75 x LLN/ >1.25 x ULN; neutrophils+bands: <1.0 x 10^3 c/uL; eosinophils: >0.750 x 10^3 c/uL; monocytes: >2000 mm3; lymphocytes: <0.750 x 10^3 c/uL/ >7.50 x 10^3 c/uL.

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= Alkaline phosphatase (ALP): >2 x ULN; aspartate aminotransferase (AST): >3 x ULN; alanine aminotransferase (ALT): >3 x ULN; G-Glutamyl transferase (GGT): >2 x ULN; Bilirubin: >2 x ULN; blood urea nitrogen (BUN): >2 x BL; creatinine: >4 x BL; potassium (K): <0.9 x LLN/ >1.1 x ULN; calcium (Ca): <0.8 x LLN/>1.2 x ULN; phosphorous (P): <0.75 x LLN/ >1.2 5 x ULN

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

Low=lower than LLN, High=greater than ULN. LLN/ULN= serum glucose (Glu): <65 mg/dL/ >220 mg/dL; fasting serum Glu: <0.8 x LLN/ >1.5 x ULN; total protein: < 0.9 x LLN/ >1.1 x ULN; albumin:<0.9 x LLN; uric acid: >1.5 x ULN. For Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]): Use ≥2 when BL value missing or value ≥4, or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

The As Treated analysis population was used for all safety summaries and was defined to include all participants who received at least one infusion of study medication.

The Mayo Scoring system ranges from 0 - 12 points and is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Higher Mayo scores indicate greater severity of disease. Mucosal healing was defined as endoscopic subscore ≤ 1 point

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of mucosal healing was not conducted for the OL as planned.

The Mayo Scoring system (range 0-12 points, high scores=greater severity of disease) is a composite index consisting of 4 disease variables (stool frequency, rectal bleeding, endoscopy evaluation, and Physician's Global Assessment). Clinical response=reduction from baseline in the Mayo score of ≥ 3 points and ≥ 30%, with accompanying decrease in the rectal bleeding subscore of ≥ 1 point or absolute rectal bleeding subscore of ≤ 1 point. Clinical remission = Mayo score of ≤ 2 points with no individual subscore exceeding 1 point. Change from Baseline= post-Baseline - Baseline value.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of clinical efficacy upon retreatment with abatacept among participants who received study drug during the IP or MP was not conducted for the OL as planned.

A electrochemiluminescent immunoassay screened sera for drug-specific antibodies, immunocompetition was used to identify specific anti-Abatacept reactivity. CTLA4 and Possibly Ig category=reactivity against extracellular domain of human CTLA4, constant regions of human IgG1, or both (CTLA4Ig; Abatacept molecule). Ig and/or Junction category=reactivity against constant regions and/or hinge region of human IgG1. Drug-induced seropositivity was defined as a post-baseline titer higher than Baseline, or any post-baseline positivity if Baseline value was missing.

All subjects with at least one post-baseline immunogenicity measurement during the study period were included in the immunogenicity data set. "Positive" was defined as "positive post-baseline IP-1" and with a titer value greater than the baseline titer value. Participants with missing baseline titer were assumed "negative" at baseline.

Participants taking oral corticosteroids (equivalent of ≤ 30 mg prednisone daily) must have met minimum treatment duration at entry into IP and had stable dose for ≥2 weeks prior to entry into the IP.

Due to the early termination of the study after preliminary IP1C results were reviewed and the primary efficacy endpoint was not achieved, the secondary subgroup analyses of corticosteroid use was not conducted for the OL as planned.