Xencor Alters Rheumatoid Arthritis Protein

Biotech firm Xencor Inc. said it has changed a protein responsible for rheumatoid arthritis into a form that can be used to treat the disease.

But the company, a Caltech spinoff based in Monrovia, acknowledged that it has much work to do before turning its discovery into a drug that would challenge Amgen Inc.’s Enbrel and Johnson & Johnson’s Remicade.

Privately held Xencor reported in the journal Science today that it used proprietary software to design a version of the tumor necrosis factor protein that blocked the action of native TNF. TNF is responsible for inflammation in rheumatoid arthritis, psoriasis and other autoimmune diseases.

Enbrel and Remicade also block TNF, but by different mechanisms of action. Xencor said its protein is cheaper to produce than Amgen and J&J;’s biotech drugs and could be more effective.

Human tests aren’t likely to begin until 2005, said Xencor Chief Executive Bassil Dahiyat, also senior author on the paper.

Xencor collaborated on the paper with scientists at the University of Texas Southwestern Medical Center at Dallas.