The six month Fast 4Ward study met primary and secondary endpoints, and showed 400mg certolizumab pegol, given every four weeks as subcutaneous monotherapy, significantly reduced signs, symptoms and pain associated with rheumatoid arthritis (RA), and improved physical function, compared to patients treated with placebo (p < 0.001). Meeting the primary endpoint, patients treated with certolizumab pegol demonstrated significantly superior ACR20 response rates at week 24 versus those on placebo (p < 0.001: 45.5% versus 9.3%). The response to treatment was rapid and significant with more than one third (36.7%) of patients on certolizumab pegol achieving an ACR20 response as early as week 1 of treatment, compared to less than 10% on placebo (p < 0.05), which was sustained throughout the study. Patients on certolizumab pegol also reported clinically significant improvements in physical function (HAQ-DI) from week 1 through to week 24, relative to placebo (p < 0.001), consistent with significantly reduced pain scores and disease activity (DAS28-3) (p < 0.001). A second six month study called Rapid 2, showed treatment with certolizumab pegol, together with methotrexate (MTX), significantly improved the clinical signs and symptoms of RA, inhibited progression of disease, and improved physical function in adult patients with active disease. In Rapid 2, patients treated with Cimzia (200mg or 400mg), together with MTX, showed significantly superior ACR20 responses as early as week 1, compared to patients treated with placebo and MTX (p < 0.01), which were sustained throughout the study (p < 0.001). Patients in both certolizumab pegol treatment arms reported clinically significant improvements in physical function (HAQ-DI) from week 1, compared to placebo versus MTX, with improvements in quality of life sustained up to week 24 (p < 0.001). In addition, certolizumab pegol, inhibited progression of structural joint damage, with significantly smaller mean change from baseline in modified total sharp score (TSS) at week 24, compared to MTX alone (p < 0.001). There were no statistically significant differences in clinical efficacy on primary or secondary endpoints between the 200mg and 400mg certolizumab pegol treatment arms. The simultaneous studies, Rapid 2 and Rapid 1, are the first large, placebo-controlled Phase III trials demonstrating the efficacy and tolerability of certolizumab pegol in the treatment of RA, as part of clinical trials program involving more than 2,300 patients.