OBJECTIVE: To assess the efficacy and safety of R788 (fostamatinib disodium), an 
inhibitor of spleen tyrosine kinase (Syk), in patients with active rheumatoid 
arthritis (RA) that did not respond to biologic therapies.
METHODS: A total of 219 patients with active RA in whom treatment with biologic 
agents had failed were enrolled in a 3-month multicenter, randomized, 
double-blind, placebo-controlled trial of R788. The primary end point was the 
percentage of patients who met the American College of Rheumatology 20% 
improvement criteria (achieved an ACR20 response) at month 3. Secondary end 
points included changes in inflammation and damage, as assessed by magnetic 
resonance imaging (MRI), and changes in the Disease Activity Score.
RESULTS: The ACR20 response in the R788 100 mg twice daily group was 38%, versus 
37% in the placebo group, at month 3. No significant differences were achieved 
in the ACR20, ACR50, or ACR70 response levels at 3 months. There were 
differences between the groups from baseline to month 3 in the secondary end 
points C-reactive protein (CRP) level and synovitis score on MRI. There were 
baseline differences in steroid use, prior biologic use, and synovitis score on 
MRI between the R788 group and the placebo group that may have affected the 
outcomes. A high placebo response rate was seen in this trial, and exploratory 
analysis suggested that this may in part have been driven by patients who 
entered the trial with an elevated erythrocyte sedimentation rate but normal CRP 
level.
CONCLUSION: Our findings indicate that there were no differences in the primary 
end point between the R788 and placebo groups. Differences were observed between 
the R788 and placebo groups in secondary end points, particularly in those 
patients who entered the study with an elevated CRP level.