The primary objectives of two phase II studies of fostamatinib were to evaluate efficacy (OSKIRA-Asia-1: NCT01569074) and long-term safety/tolerability (OSKIRA-Asia-1X: NCT01640054) in patients from Asia with active RA despite MTX treatment.
OSKIRA-Asia-1 was a 12-week, multicentre, double-blind, placebo-controlled, parallel-group study. Patients were randomized to receive one of four fostamatinib doses (groups A-D; n = 31, 33, 33, 33) or placebo (group E; n = 33). OSKIRA-Asia-1X was a long-term extension study (100 mg fostamatinib qd) of patients who completed OSKIRA-Asia-1. RA signs and symptoms were measured by ACR response criteria and DAS based on a 28-joint count. Physical function status was assessed with the HAQ-Disability Index. Safety findings were monitored.
In OSKIRA-Asia-1, fostamatinib revealed numerical improvements in ACR 20% response (ACR20) at week 12 in group A (100 mg bid) and group B (100 mg bid, then 150 mg qd) vs placebo. Statistically significant improvements in ACR20 and ACR50 at week 8 and in ACR70 at week 12, and statistically significant achievement in low disease activity (defined as DAS based on a 28-joint count ≤3.2 based on C-reactive protein) occurred in groups A and B. Improvement in physical function was numerically higher in group A. The most common adverse events were hypertension, diarrhoea and neutropenia. In OSKIRA-Asia-1X, the most common adverse events were nasopharyngitis, hypertension, RA and neutropenia.
OSKIRA-Asia-1 trial registration: https://clinicaltrials.gov, NCT01569074; OSKIRA-Asia-1X trial registration: https://clinicaltrials.gov, NCT01640054.
Fostamatinib achieved both statistically and clinically significant improvements in RA signs and symptoms. The safety and tolerability of fostamatinib (plus MTX) were consistent with previous studies.