New treatment for psoriasis offers hope of fewer side effects

Patients with severe psoriasis might be able to look forward to a new treatment that cuts the risk of long-term kidney damage, suggests research in The Lancet.

ISA247, a new type of calcineurin inhibitor, designed for the treatment of autoimmune disease and organ transplant rejection, has shown itself to be safe and effective in a phase III trial of 451 patients.

The results indicated a strong link between dose and response, suggesting that patients can be more accurately dosed to minimise the risk of side effects.

One of the most effective treatments for psoriasis is the calcineurin inhibitor ciclosporin.  But used long term, this drug can damage the kidneys, say the Canadian authors.

Other newer treatments, such as infliximab are expensive, are not always easy to use and as yet it's not known how safe and effective they are over the long term, they add.

The researchers carried out a randomized placebo controlled trial of 451 patients aged 18 to 65 years with plaque psoriasis involving at least 10% of the body surface area (moderate to severe disease).

The patients were divided into four groups, one of which was given placebo and the rest of whom received their treatment orally twice daily at doses ranging from 0.2 mg/kg body weight up to 0.4 mg/kg body weight.

How well the treatment worked was measured by whether it caused a 75% reduction in the psoriasis area and severity index score (PASI 75) at week 12.

Patients were monitored for a total of 24 weeks.

The higher the dose of ISA247, the better it worked.

In the group given 0.4 mg/kg 47% of patients achieved PASI 75; in the 0.3 mg/kg group, this proportion was 25%; and in the 0.2 mg/kg group, 16%.

Four of the 115 patients taking the placebo (4%) achieved PASI 75.

"The strong correlation between ISA247 concentrations and efficacy might allow for accurate dosing of patients compared with existing calcineurin inhibitors," suggest the authors.

In an accompanying commentary, Dr Luigi Naldi, Unit of Dermatology and GISED Study Centre, Ospedali Riuniti, Bergamo, Italy, says that the advent of new treatment options for psoriasis calls for far more observational studies and comparative research in real-life situations rather than in the relatively protected environment of clinical trials.

The Lancet 2008; 371: 1337-42