AstraZeneca's (AZN -0.25%) phase 3 study of the effectiveness and safety of developmental rheumatoid arthritis drug fostamatinib succeeded in meeting two primary endpoints. The OSKIRA-1 trial showed that fostamatinib increased ACR20 response rates in two different patient groups, according to a statement on the matter from the company. (ACR scores are used in measuring changes in rheumatoid arthritis symptoms.)

The drug also proved safe in the study, with patients tolerating fostamatinib about as well as they had in an earlier phase 2 study. Reported side effects were mild, including diarrhea, nausea, and hypertension.

Dr. Briggs W. Morrison, AstraZeneca's chief medical officer and executive vice president of global medicine development, spoke about fostamatinib's success in the statement, saying, "These top-line results provide important information on the efficacy and safety of fostamatinib and demonstrate that the compound has an effect on the signs and symptoms of rheumatoid arthritis."

The success comes as the rheumatoid arthritis market heats up. Some of the leading treatments for the disease include best-selling immunology drugs such as AbbVie's (NYSE: ABBV) Humira and Johnson & Johnson's (NYSE: JNJ) Remicade, each of which made more than $6 billion for their companies last year.