The effects of the spleen tyrosine kinase inhibitor fostamatinib on ambulatory blood pressure in patients with active rheumatoid arthritis: results of the OSKIRA-ABPM (ambulatory blood pressure monitoring) randomized trial.

Clinical trials of fostamatinib in patients with rheumatoid arthritis showed blood pressure (BP) elevation using clinic measurements. The OSKIRA-ambulatory BP monitoring trial assessed the effect of fostamatinib on 24-hour ambulatory systolic BP (SBP) in patients with active rheumatoid arthritis. One hundred thirty-five patients were randomized to fostamatinib 100 mg twice daily (bid; n = 68) or placebo bid (n = 67) for 28 days. Ambulatory, clinic, and home BPs were measured at baseline and after 28 days of therapy. Primary end point was change from baseline in 24-hour mean SBP. Fostamatinib increased 24-hour mean SBP by 2.9 mm Hg (P = .023) and diastolic BP (DBP) by 3.5 mm Hg (P <.001) versus placebo. Clinic/home-measured BPs were similar to those observed with ambulatory BP monitoring. After treatment discontinuation (1 week), clinic BP values returned to baseline levels. Fostamatinib induced elevations in 24-hour mean ambulatory SBP and DBP. BP elevations resolved with fostamatinib discontinuation.