Dose-finding Study of GLPG0634 as Monotherapy in Active Rheumatoid Arthritis (RA) Patients (DARWIN2)

- Treatment duration will be 24 weeks in total.

- However, at Week 12, all subjects on placebo and the subjects on the 50 mg dose who
have not achieved 20% improvement in swollen joint count (SJC66) and tender joint count
(TJC68) will be assigned (automatically via interactive web response system (IWRS)) to
100 mg q.d. in a blinded fashion and will continue treatment until Week 24.

- Subjects in the other groups will maintain their randomized treatment until Week 24.

Inclusion Criteria:

- male or female subjects who are ≥18 years of age on the day of signing informed
consent,

- have a diagnosis of RA since at least 6 months and meeting the 2010 ACR/EULAR
criteria of RA and ACR functional class I-III,

- have ≥6 swollen joints (from a 66-joint count) and

≥8 tender joints (from a 68-joint count) at Screening and at Baseline,

- Screening serum c-reactive protein ≥ 0.7 x upper limit of laboratory normal range
(ULN),

- have shown an inadequate response in terms of either lack of efficacy or toxicity to
MTX,

- have agreed to be washed out from MTX for a period of at least 4 weeks before or
during the Screening period.

Exclusion Criteria:

- current therapy with any non-biological disease modifying anti-rheumatic drug
(DMARD), with the exception of antimalarials, which must be at a stable dose for at
least 12 weeks prior to Screening,

- current or previous RA treatment with a biologic DMARD, with the exception of
biologic DMARDs: administered in a single clinical study setting, and; more than 6
months prior to Screening (12 months for rituximab or other B cell depleting agents),
and; where the biologic DMARD was effective, and if discontinued, this should not be
due to lack of efficacy,

- previous treatment at any time with a cytotoxic agent, other than MTX, before
Screening.