About 59 percent of patients receiving the higher dose of secukinumab reported a 90 percent improvement in symptoms, and more than 28 percent said their psoriasis had cleared up completely.
"Not only was this phenomenally effective, but it was very quick," Lebwohl said.
The other trial reported similar results. The study provided either 300 mg or 150 mg of secukinumab to half of a pool of 1,306 psoriasis patients, with doses delivered the same as in the first trial.
In this trial, more than three-quarters (77 percent) of patients receiving the high dose of secukinumab experienced a 75 percent improvement in their psoriasis symptoms within 12 weeks, compared with 44 percent of those who received Enbrel and about 5 percent who got a placebo, the investigators found.
About 54 percent of secukinumab patients reported a 90 percent improvement in their symptoms, compared with 20 percent for Enbrel, the study found. One out of four patients reported that their psoriasis had completely cleared up with secukinumab, compared with one out of 20 for Enbrel.
In both trials, secukinumab proved relatively safe. The only side effect appears to be an increased risk of infection, which was higher than placebo in both studies but similar to that of Enbrel.
"The psoriasis drugs that we have used in past years suppressed big parts of the immune system, and because of that they had a lot of side effects," Lebwohl said. "This one appears to block the smallest part yet, and it appears to block the right part because it is the most effective of all the drugs to treat psoriasis yet."
Van Voorhees said the trials add up to a "very promising new agent" for treating psoriasis. The drug now awaits U.S. Food and Drug Administration approval.
"It's more effective than one of our gold-standard therapies, it's well-tolerated, and the only risk seems to be an increased risk of infection," Van Voorhees said.
The trials were funded by the drug's manufacturer, Novartis Pharmaceuticals.