Study to Assess Steady-State Trough Concentrations, Safety, and Immunogenicity of Abatacept After Subcutaneous (SC) Administration to Subjects With Rheumatoid Arthritis (RA)

Abatacept \& Placebo as IV \& SC solution, IV/SC, Abatacept 500 mg IV (Day 1)/Abatacept 75 mg SC (once weekly for 12 weeks) or Placebo IV(Day 1)/Placebo SC (once weekly for 12 weeks), 12 weeks then long term extension (LTE).

Abatacept \& Placebo as IV \& SC solution, IV/SC, Abatacept 500 mg IV (Day 1)/Abatacept 125 mg SC (once weekly for 12 weeks) or Placebo IV(Day 1)/Placebo SC (once weekly for 12 weeks), 12 weeks then long term extension (LTE).

Abatacept \& Placebo as IV \& SC solution, IV/SC, Abatacept 750 mg IV (Day 1)/Abatacept 125 mg SC (once weekly for 12 weeks) or Placebo IV(Day 1)/Placebo SC (once weekly for 12 weeks), 12 weeks then long term extension (LTE).

Abatacept \& Placebo as IV \& SC solution, IV/SC, Abatacept 1000 mg IV (Day 1)/Abatacept 125 mg SC (once weekly for 12 weeks) or Placebo IV(Day 1)/Placebo SC (once weekly for 12 weeks), 12 weeks then long term extension (LTE).

Abatacept \& Placebo as IV \& SC solution, IV/SC, Abatacept 1000 mg IV (Day 1)/Abatacept 200 mg SC (once weekly for 12 weeks) or Placebo IV(Day 1)/Placebo SC (once weekly for 12 weeks), 12 weeks then long term extension (LTE).

Solution in pre-filled syringes, Subcutaneously, 125 mg, Weekly