Causes of Psoriasis
Psoriasis is caused by an overactive immune system that speeds up the growth cycle of the skin. In normal skin, new cells surface about once a month. In psoriasis, new cells surface in just three to four days. These cells build up into thick patches that have a silvery, flaking crust.
Psoriasis is thought to affect about 2% of the population, and its misery may go deeper than skin.
"Psoriasis is a systemic disease," Gordon says. People with psoriasis also have higher risks of cardiovascular disease, diabetes, depression, and alcoholism, he says. "So when people think of psoriasis as limited to the skin it really isn't laying credence to the severity of the disease and the overall health of the individual. It's very debilitating as well."
Briakinumab helps stem the body's overactive immune system by blocking two proteins that drive inflammation.
A similar drug, Stelara, which also blocks the same two proteins, was approved by the FDA in 2009.
In studies, Stelara did not appear to be associated with as many adverse events, Reich says, perhaps because it is not as complete an inhibitor of the two proteins as briakinumab or because it is given at lower doses.
Even if the drug is never approved, Reich says, the study is still important because it proves that highly effective treatment of psoriasis is possible.
"I take this briakinumab as ... a shining example of how far we can get with efficacy. On the other hand, I hear the warning signal that is contained in the study that we need to make sure that the big benefit contained in the study is not putting the patient at risk," he says.
Other experts say the study is important because it provides some of the first information about how well methotrexate works.
After six months, the study showed about 40% of patients who were taking weekly doses of methotrexate had at least a 75% improvement in their skin symptoms. That number dropped to 24% after a full year of treatment. Still fewer achieved complete clearance of their skin lesions.