Pfizer arthritis drug wins approval, ready to challenge Humira

Nov 6 (Reuters) - U.S. regulators on Tuesday approved Pfizer Inc's Xeljanz treatment for rheumatoid arthritis, one of the company's most potentially lucrative experimental drugs, which is now poised to compete with Abbott Laboratories Inc's top-selling Humira.

The U.S. Food and Drug Administration said in a release it had approved Pfizer's pill for patients with moderate to severe rheumatoid arthritis who have not benefited from or been able to tolerate the standard oral treatment, methotrexate.

Industry analysts have predicted Pfizer's drug, better known by its chemical name tofacitinib, could garner annual peak sales of up to $3 billion. As a pill, it could prove more attractive to some patients than Abbott's $8 billion-a-year injectable Humira. Abbott has said the Pfizer drug poses no major competitive threat to its flagship product.