In
a phase III trial, a new treatment for moderate to severe plaque
psoriasis has been proven safe and effective. Additionally, there is
almost a linear relationship between drug dose and response, which
suggests that patients can be accurately dosed in order to achieve a
clinical response while minimizing side effects. These results were
published on April 18, 2008 in The Lancet.
The most
effective treatment for psoriasis presently is the calcineurin
inhibitor ciclosporin.? However, use of
this drug has a toxic effect on the kidneys, which restricts its
long-term use. Newer treatments, such as infliximab, are safe and
effective for plaque psoriasis treatment, but their high costs,
inconvenient administration methods, and general lack of safety and
effectiveness data restrict their widespread use.
This new
treatment, ISA247, is a new type of calcineurin inhibitor intended to
treat autoimmune diseases such as psoriasis, uveitis, and organ
transplant rejection. To investigate this new treatment, Dr Kim Papp,
Probity Medical Reseach, Waterloo, Ontario, Canada, conducted a
placebo-controlled randomized trial on 451 patients aged 18-65 years
with plaque psoriasis involving at least 10% of body surface area.
The
patients were divided into four groups, each of which receieved
treatment orally twice daily at dermatology clinics. The groups were
dosed the following amounts of ISA247: the first, with 107 patients,
received 0.2 mg/kg body weight; the second, with 113 patients,
receieved 0.3 mg/kg body weight; the third, with 116 patients,
receieved 0.4 mg/kg body weight; the fourth, with 115 patients,
received a placebo. Patients were followed up for a total of 24 weeks.
Effectiveness of treatment was measured by whether a 75% reduction in
psoriasis area and severity index score (PASI 75) at week 12. It was
found that when the ISA247 dose was higher, it performed better. That
is, in the 0.4 mg/kg group, 47% of patients achieved PASI75, in the 0.3
mg/kg group it was 25%, in the 0.2 mg/kg group it was 16%, and in the
placebo 4%.
The authors conclude with positive comments about the potential of this
new drug. "ISA247 was safe and effective in the treatment of patients
with
moderate to severe psoriasis during 24 weeks, with the highest dose
providing the best efficacy. The strong correlation between ISA247
concentrations and efficacy might allow for accurate dosing of patients
compared with existing calcineurin inhibitors."
Dr Luigi Naldi, of the Unit of Dermatology and GISED Study Centre,
Ospedali Riuniti di Bergamo, Italy, contributed a comment in which he
notes the future implications of these results on psoriasis research.
"New therapeutic options for the treatment of psoriasis create an
increasing need for long-term observational studies and comparative
trials in real life situations."
Efficacy of ISA247 in plaque psoriasis: a randomised,
multicentre, double-blind, placebo-controlled phase III study
K Papp, R Bissonnette, L Rosoph, N Wasel, C W Lynde, G Searles, N H
Shear, R B Huizinga, W P Maksymowych
Lancet 2008; 371: 1337-42
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Written by Anna Sophia McKenney