Roche said on Thursday its Actemra drug, developed by Japanese partner Chugai, was better than current standard treatments in preventing the progression of joint destruction in patients with rheumatoid arthritis.

According to late-stage clinical trial data presented at a meeting in San Diego, the drug when used alone was superior to conventional drugs, known as DMARDs, in inhibiting the spread of joint destruction.

The data also showed that Actemra dramatically improved the painful and disabling symptoms of patients with rheumatoid arthritis.

Actemra is one of two drugs Roche hopes will give it a foothold in the market for treating rheumatoid arthritis (RA), a debilitating autoimmune disease in which the lining of joints becomes inflamed causing joint damage and destruction.