Dosing Flexibility Study in Patients With Rheumatoid Arthritis

Subjects with a stable methotrexate (MTX) dose enter the run-in period in which certolizumab
pegol (CZP) will be administered at a dose of 400 mg (2 injections) at Weeks 0, 2, and 4 and
at a dose of 200 mg with placebo (1 injection placebo, 1 injection CZP) at Weeks 6, 8, 10,
12, 14 and 16. The dose of MTX should be stable for at least 2 months prior to the Baseline
visit and will remain stable throughout the trial, unless there is a need to reduce the dose
for reasons of toxicity.

At the Week 18 visit, subjects who were ACR20 (American College of Rheumatology 20%
Improvement) responders at Week 16 will be randomized in a double-blinded way to receive
either 400 mg CZP given every 4 weeks and placebo given every 4 weeks given as two injections
(alternating CZP and placebo every two weeks) plus MTX, 200 mg CZP and placebo administered
every 2 weeks (one injection of each) plus MTX, or Placebo administered as two injections
every 2 weeks plus MTX. Non-responders will be withdrawn from the study.

Inclusion Criteria:

- Patients with established adult rheumatoid arthritis currently on Methotrexate for at
least 3 months

Exclusion Criteria:

- All concomitant diseases or pathological conditions that could interfere and impact
the assessment of the study treatment

- Previous clinical trials participation and previous biological therapy that could
interfere with the results of the present clinical trial