Abbott Laboratories is celebrating the news that a second Phase III trial has found that treatment with its rheumatoid arthritis drug Humira can reduce the signs and symptoms of the skin disease psoriasis.

The REVEAL study evaluated both the short-term and sustained clinical efficacy and safety of Humira (adalimumab) in 1,200 patients with moderate-to-severe chronic plaque psoriasis and the data showed that 71% of patients treated with the drug showed at least 75% skin clearance after 16 weeks, compared with 6.5% of patients given a placebo.

Moreover, the trial also found that most patients who responded to Humira and used it continuously were able to maintain clearance for one year. The drug was generally well tolerated, Abbott said, with the most commonly reported adverse events being upper respiratory tract infection, nasopharyngitis and headache.

The REVAL results follow last year’s CHAMPION Phase III study which showed that 80% of patients with moderate-to-severe psoriasis saw a 75% improvement of their symptoms after 16 weeks, compared with 36% who were given the standard treatment, methotrexate.

Armed with the data of these two studies, Abbott said it now plans to file Humira, which works by blocking tumour necrosis factor, for US and European regulatory approval as a treatment for psoriasis during the first half of 2007. The company noted that the disease affects an estimated 125 million people worldwide, with approximately 25% of patients experiencing moderate to severe disease.

Humira is currently approved to treat psoriatic arthritis, a form of arthritis that affects up to 30% of people with the skin condition and a new approval would boost Abbott’s already-healthy sales of the drug. Revenues of the drug grew 40.6% to $620 million in the fourth quarter just gone, thanks in part to the drug being granted the additional US approval for psoriatic arthritis and ankylosing spondylitis, a rheumatological disease of the spine.

Anti-TNF competitors in the psoriasis field would include Johnson & Johnson‘s Remicade (infliximab) and Wyeth/Amgen’s Enbrel (etanercept), while other biologics already approved in this setting include Biogen Idec's Amevive (alefacept) and Merck-Serono/Genentech's Raptiva (efalizumab),

Sales could rise even further as Abbott is hoping to secure approval of Humira in Crohn's disease in the USA and Europe later this year.