Gilead Sciences Inc. and Tokyo-based Eisai Co. Ltd. entered an agreement to distribute and co-promote Gilead's rheumatoid arthritis treatment filgotinib in Japan.

Under the deal, Foster City, Calif.-based Gilead will be responsible for filgotinib's manufacturing and marketing approval while Eisai will oversee the medicine's distribution in Japan. The European Medicines Agency is currently reviewing Gilead's marketing application for filgotinib and the company has also filed an application with the Japanese Ministry of Health, Labor and Welfare for the medicine's approval.

Filgotinib, which inhibits an enzyme called Janus kinase 1, is not yet approved anywhere in the world. The medicine, which has been found to benefit patients in phase 3 trials, is also being evaluated as a treatment for ulcerative colitis, Crohn's disease and psoriatic arthritis.

Rheumatoid arthritis affects approximately 600,000 to one million people in Japan.

Gilead is developing filgotinib with Galapagos NV, and the companies have an agreement in place to commercialize filgotinib in inflammatory indications.