Dose-finding Study of GLPG0634 as add-on to Methotrexate in Active Rheumatoid Arthritis Patients (DARWIN1)

- Treatment duration will be 24 weeks in total.

- However, at Week 12, subjects on placebo who have not achieved a 20% improvement in
swollen joint count(SJC66) and tender joint count (TJC68) will be re-randomized
(automatically via interactive voice/web response [IXRS]) to treatment to receive
GLPG0634 100 mg q.d. or 50 mg b.i.d. doses in a blinded fashion, subjects on 50 mg q.d.
who have not achieved a 20% improvement in SJC66 and TJC68 will be assigned to 100 mg
q.d. and subjects on 25 mg b.i.d. who have not achieved a 20% improvement in SJC66 and
TJC68 will be assigned to 50 mg b.i.d. All will continue the study 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 received MTX for ≥6 months and have been on a stable dose (15 to 25 mg/week) of
MTX for at least 4 weeks prior to Screening and willing to continue on their current
regimen for the duration of the study. Stable doses of MTX as low as 10 mg/week are
allowed when there is documented evidence of intolerance or safety issues at higher
doses.

Exclusion Criteria:

- current therapy with any disease-modifying anti-rheumatic drugs (DMARD) other than
MTX,

- current or previous RA treatment with a biologic DMARD, with the exception of
biologic DMARDs administered in a single clinical study setting more than 6 months
prior to Screening (12 months for rituximab or other B cell depleting agents), 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.