FRI0232 Consistent efficacy and safety outcomes between european and japanese subjects with rheumatoid arthritis following treatment with mavrilimumab in the phase 2 earth study

Background GM-CSF is considered a key mediator in the disease pathogenesis associated with RA. Mavrilimumab (CAM-3001), a human IgG4 mAb that targets GM-CSFRα, may provide clinical benefit to patients with moderate-to-severely active RA. Objectives To investigate the efficacy and safety of multiple ascending doses (10–100 mg q2w) of mavrilimumab in adult subjects from Europe (EU) and Japan (JA) with active RA. Methods Subjects (EU n=239; JA n=51) with moderate-to-severely active RA (DAS28-CRP ≥3.2) of ≥3 mos disease duration, receiving stable doses of MTX (7.5–25 mg/wk), and ACPA+ and/or RF+ were randomized 2:1 to subcutaneous mavrilimumab (10, 30, 50, or 100 mg) or placebo (PBO) (safety population); 284 subjects (mavrilimumab 192 [EU n=158; JA n=34]; placebo (PBO) 92 [EU n=75; JA n=17]) were included in the intent-to-treat (ITT) population. Subjects received the study drug every other wk for 12 wks, followed by a 12-wk follow-up (f/u) period. The primary endpoint was the proportion of mavrilimumab subjects achieving a DAS28-CRP decrease ≥1.2 from baseline vs PBO at wk 12. Secondary endpoints included DAS28-CRP