Rituxan, the lymphoma drug developed by

Genentech

(DNA)

and

Biogen

(BIIB) - Get Report

, worked better than a placebo in treating patients with rheumatoid arthritis in a phase III study, the companies said.

The study group comprised patients who had an inadequate or no response to so-called anti-TNF drugs, which generally speaking include

Abbott Labs'

(ABT) - Get Report

Humira,

Johnson & Johnson's

(JNJ) - Get Report

Remicaid and

Amgen's

(AMGN) - Get Report

Enbrel.

According to Genentech and Biogen, Rituxan met its primary endpoint of a greater proportion of Rituxan-treated patients achieving a response standard defined by the American College of Rheumatology in the 24th week of treatment, compared to a placebo. Both classes of patients were taking the chemotherapy methotrexate.

The Rituxan antibody targets positive B cells that are suspected of playing various roles in promulgating rheumatoid arthritis. It's been approved as a treatment for non-Hodgkins lymphoma since 1997.

"These are the first phase III Rituxan data to demonstrate clinical improvement in this difficult-to-treat RA patient population. The findings add to the growing body of evidence that selectively targeting B cells may provide an important new treatment approach for this debilitating disease," Genentech said.