Labelling for Abbott’s anti-TNF drug Humira has been expanded in the USA to include data showing that it cuts the rate of structural joint damage in patients with psoriatic arthritis.

Humira (adalimumab) was approved for psoriatic arthritis a little over year ago, and is also indicated for the treatment of moderate-to-severe rheumatoid arthritis and ankylosing spondylitis, a rheumatological disease of the spine.

An estimated one million people in the USA suffer from psoriatic arthritis, a chronic diseases that combines symptoms of arthritis, including joint pain and inflammation, and those of psoriatic skin disease, such as painful, raised red lesions covered by silvery white scales.

The new labelling should help Humira compete in the increasingly competitive market for anti-TNF drugs, although it hardly needs a hand at present: sales of the drug rose a hefty 52% to $541 million in the third quarter, and it now accounts for nearly 10% of Abbott's total revenues.

Further momentum for Humira should also come next year when Abbott is scheduled to secure approval of Humira in Crohn’s disease in the USA and Europe, opening up anther target population of more than a million people for the drug.