Eli Lilly and Co and Incyte Corp said their experimental drug was found to be more effective in treating rheumatoid arthritis than a commonly prescribed medicine, in a late-stage study.

The drug, baricitinib, reduced signs and symptoms of the inflammatory disorder better than the decades-old treatment, methotrexate, after 24 weeks, the companies said on Tuesday.

Baricitinib was well tolerated and there were no differences in safety issues between the two drugs, the companies said.

Previous studies showed that the drug was more effective than two other classes of treatments, including biologic drugs, Incyte Chief Drug Development Officer Rich Levy said.

AbbVie Inc's Humira is currently the highest-earning biologic drug for rheumatoid arthritis.

Humira, touted as the world's most successful biologic drug, generated $12.5 billion in sales globally in 2014.

Lilly's shares closed at $79.74 on Monday on the New York Stock Exchange. Incyte's shares closed at $95.16.