Patients taking AstraZeneca RA drug show partial improvement

NEW YORK — An experimental drug developed by AstraZeneca for rheumatoid arthritis produced mixed results in measurements of patients' conditions, according to results of a late-stage clinical trial.

AstraZeneca announced initial results of the phase-3 "OSKIRA-1" trial of fostamatinib, which it calls the first oral spleen tyrosine kinase inhibitor in development for RA.

The goals of the study were to measure signs and symptoms of RA based on two measures, known as ACR20 and mTSS after 24 weeks of treatment. The ACR20 measure indicated statistically significant improvement in patients' conditions compared with those who took placebo, while mTSS did not.

ACR20, which stands for American College of Rheumatology 20, means a patient has at least 20% fewer tender joints and at least 20% fewer swollen joints, as well as 20% improvement in various assessments of the patient's condition. The mTSS, which stands for modified total sharp score, measures bone erosion and joint-space narrowing using X-rays.