Safety, Efficacy and Pharmacokinetics Study of ALD518 in Patients With Active Rheumatoid Arthritis

This will be a phase II, parallel-group, double-blind, randomized, placebo-controlled study of ALD518 in patients with active RA with an inadequate response to methotrexate. Enrolled patients will be screened within a 4-week period (Day -35 to -7). within a 12-day period (Day-14 to -3) before initial dosing on Day 1 patients will be randomized to one of the following four treatment groups: Group A: 2x ALD518 80 mg Group B: 2x ALD518 160 mg Group C: 2x ALD518 320 mg Group D: 2x placebo In all treatment groups patients will continue to take a stable dose of methotrexate. There will be a total of 11 visits. The total duration of the patient study participation will be approximately 16 weeks (excluding the screening period).