Recruitment Details

Key information relevant to the recruitment process for the overall study, such as dates of the recruitment period and locations
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Pre-Assignment Details

Significant events and approaches for the overall study following participant enrollment, but prior to group assignment
191 participants were enrolled and 21 were not randomized. Reasons for this included: adverse events (AEs) (2); participant withdrew consent (5); lost to follow up (1); participant no longer meets study criteria (13).

Reporting Groups

	Description
Abatacept (30/10)	Participants were administered intravenous (iv) infusions of abatacept (30 mg/kg - calculated dose) over approximately 30 minutes on Days 1 and 15, followed by 10 mg/kg (fixed dose) abatacept infusion on Day 29 and every 28 days thereafter up to and including Day 141. All participants received a calculated dose on Day 1 and 15 followed by fixed dose based on their screening visit weight i.e. for participants weighing < 60 kg received 500 mg, participants weighing 60 kg to 100 kg received 750 mg and participants weighing > 100 kg received 1000 mg.
Abatacept (10/10)	Participants were administered iv infusions of abatacept (10 mg/kg) over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141. All participants received a dose based on their screening visit weight as per rheumatoid arthritis label (participants weighing < 60 kg received 500 mg, participants weighing 60 kg to 100 kg received 750 mg and participants weighing > 100 kg received 1000mg).
Abatacept (3/3)	Participants were administered iv infusions of abatacept (3 mg/kg - calculated dose) over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141. All participants received calculated dose based on their screening visit weight.
Placebo	Participants were administered iv infusions of either dextrose 5% solution or 0.9% sodium chloride solution at a constant rate over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141.

Participant Flow:   Overall Study

	Abatacept (30/10)	Abatacept (10/10)	Abatacept (3/3)	Placebo
STARTED	43	40	45	42
COMPLETED	37 [1]	34 [2]	43 [2]	33 [2]
NOT COMPLETED	6	6	2	9
Adverse Event	1	2	1	3
Lack of Efficacy	3	4	0	3
Participant not meeting study criteria	0	0	0	1
Participant withdrew consent	2	0	0	2
Pregnancy	0	0	1	0

Reporting Groups

	Description
Abatacept (30/10)	Participants were administered intravenous (iv) infusions of abatacept (30 mg/kg - calculated dose) over approximately 30 minutes on Days 1 and 15, followed by 10 mg/kg (fixed dose) abatacept infusion on Day 29 and every 28 days thereafter up to and including Day 141. All participants received a calculated dose on Day 1 and 15 followed by fixed dose based on their screening visit weight i.e. for participants weighing < 60 kg received 500 mg, participants weighing 60 kg to 100 kg received 750 mg and participants weighing > 100 kg received 1000 mg.
Abatacept (10/10)	Participants were administered iv infusions of abatacept (10 mg/kg) over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141. All participants received a dose based on their screening visit weight as per rheumatoid arthritis label (participants weighing < 60 kg received 500 mg, participants weighing 60 kg to 100 kg received 750 mg and participants weighing > 100 kg received 1000mg).
Abatacept (3/3)	Participants were administered iv infusions of abatacept (3 mg/kg - calculated dose) over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141. All participants received calculated dose based on their screening visit weight.
Placebo	Participants were administered iv infusions of either dextrose 5% solution or 0.9% sodium chloride solution at a constant rate over approximately 30 minutes on Days 1, 15, 29 and every 28 days thereafter up to and including Day 141.

Baseline Measures

	Abatacept (30/10)	Abatacept (10/10)	Abatacept (3/3)	Placebo	Total
Number of Participants   [units: participants]	43	40	45	42	170
Age   [units: years] Median ( Full Range )	54.0     ( 29.0 to 69.0 )	51.5     ( 26.0 to 73.0 )	51.0     ( 29.0 to 72.0 )	53.0     ( 30.0 to 82.0 )	52.0     ( 26.0 to 82.0 )
Gender   [units: participants]
Female	23	14	23	19	79
Male	20	26	22	23	91
Race/Ethnicity, Customized   [units: participants]
White	43	38	44	41	166
Asian	0	2	1	0	3
Pacific	0	0	0	1	1
Weight   [units: kilograms] Mean ± Standard Deviation	92.9  ± 21.3	85.0  ± 17.9	85.0  ± 19.1	96.0  ± 19.4	89.7  ± 19.9

1.  Primary:

Number of Participants With American College of Rheumatology (ACR 20) Response at Day 169 (Double-blind Period)   [ Time Frame: Baseline and Day 169 ]

2.  Secondary:

Number of Participants With an Investigators Global Assessment Score of Clear or Almost Clear at Day 169 (Double-blind Period)   [ Time Frame: Day 169 ]

3.  Secondary:

Mean Percentage of Change From Baseline in Target Lesion Score at Day 169 (Double-blind Period)   [ Time Frame: From baseline to Day 169. ]

4.  Secondary:

Mean Change From Baseline in Physical Component Summary Score as Measured by the Short Form 36 at Day 169 (Double-blind Period)   [ Time Frame: From baseline to Day 169. ]

5.  Secondary:

Mean Change From Baseline in the Mental Component Summary Score as Measured by the Short Form 36 at Day 169 (Double-blind Period)   [ Time Frame: From Baseline to Day 169 ]

6.  Secondary:

Number of Participants Achieving a Reduction of at Least 0.3 Unit From Baseline in Health Assessment Questionnaire Disability Index Scores at Day 169 (Double-blind Period)   [ Time Frame: From baseline to Day 169 ]

7.  Secondary:

Number of Participants Who Died and With SAEs, AEs, AEs Leading to Discontinuation, SAEs Leading to Discontinuation, Drug-related AEs, and Drug-related SAEs (Double-blind Period)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

8.  Secondary:

Number of Participants With Marked Abnormalities in Hematology (Double-blind Period)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

9.  Secondary:

Number of Participants With Marked Abnormalities in Hematology (Double-blind Period)(Continued)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

10.  Secondary:

Number of Participants With Marked Abnormalities in Serum Chemistry (Double-blind Period)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

11.  Secondary:

Number of Participants With Marked Abnormalities in Serum Chemistry (Double-blind Period)(Continued)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

12.  Secondary:

Number of Participants With Marked Abnormalities in Serum Chemistry (Double-blind Period) (Continued)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

13.  Secondary:

Number of Participants With Marked Abnormalities in Urinalysis (Double-blind Period)   [ Time Frame: Events recorded at each participant encounter, from start of study drug therapy up to 56 days after the last dose of double-blind period or start of open-label period, whichever occurred earlier. ]

14.  Secondary:

Number of Participants With Positive Responses for Serum Levels of Abatacept-specific Antibodies (Anti-Abatacept-C)(Double-blind Period)   [ Time Frame: Day 1 prior to the first dose of open-label period ]

15.  Secondary:

Mean Serum Concentrations of Abatacept (Double-blind Period)   [ Time Frame: Blood samples were collected prior to study medication infusion on Days 1, 15, 29, 57, 85, 113, 141 and Day 169. ]

16.  Secondary:

Mean Serum Trough Concentrations (Cmin) of Abatacept (Double-blind Period)   [ Time Frame: Blood samples were collected prior to study medication infusion on Day 1, 15, 29, 57, 85, 113, 141 and Day 169. ]

17.  Secondary:

Population PK (POPPK) Analysis of the PK Parameters (Double-blind Period)   [ Time Frame: Blood samples were collected just prior to the administration of the intravenous infusion on Days 1, 15, 29, 57, 85, 113, 141, and 169. ]

18.  Primary:

Number of Participants Who Died and With Serious Adverse Events (SAEs), AEs, AEs Leading to Discontinuation, SAEs Leading to Discontinuation, Drug-related AEs, and Drug-related SAEs (Double-blind Period) (Open-label Period)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

19.  Primary:

Number of Participants With Marked Abnormalities in Hematology (Open-label Period)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

20.  Primary:

Number of Participants With Marked Abnormalities in Hematology (Open-label Period)(Continued)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

21.  Primary:

Number of Participants With Marked Abnormalities in Serum Chemistry (Open-label Period)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

22.  Primary:

Number of Participants With Marked Abnormalities in Serum Chemistry (Open-label Period) (Continued)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

23.  Primary:

Number of Participants With Marked Abnormalities in Urinalysis (Open-label Period)   [ Time Frame: From start of study drug therapy in open-label period up to 56 days after the last dose of open-label period. ]

24.  Primary:

Number of Participants With Positive Responses for Serum Levels of Abatacept-specific Antibodies (Open-label Period)   [ Time Frame: From start of Open-label period up to 85 days after last dose of open-label period. ]

25.  Secondary:

Number of Participants With ACR 20, ACR 50, ACR 70, ACR 90 Responses at Days 365 and 729 (Open-label Period)   [ Time Frame: From Day 169, Day 365 and Day 729 during the open-label period ]

26.  Secondary:

Number of Participants With an Investigators Global Assessment Score of Clear or Almost Clear at Days 365 and 729 (Open-label Period)   [ Time Frame: From Days 169, 365, and 729 during the open-label period. ]

27.  Secondary:

Mean Percentage Change From Baseline in Target Lesion Score at Day 365 and Day 729(Open-label Period)   [ Time Frame: From baseline to Days 365 and 729 during the open-label period. ]

28.  Secondary:

Mean Change From Baseline in Physical Component Summary Score as Measured by the Short Form 36 at Days 365 and 729 (Open-label Period)   [ Time Frame: From Baseline to Days 365 and 729 during the open-label period. ]

29.  Secondary:

Mean Change From Baseline in Mental Component Summary Score as Measured by the Short Form 36 at Days 365 and 729 (Open-label Period)   [ Time Frame: From baseline to Days 365 and 729 during the open-label period. ]

30.  Secondary:

Number of Participants Achieving a Reduction of at Least 0.3 Unit From Baseline in Health Assessment Questionnaire - Disability Index Score at Days 365 and 729 (Open-label Period)   [ Time Frame: From baseline to Days 365 and 729 during the open-label period. ]