WEDNESDAY, Feb. 7 (HealthDay News) -- A new monoclonal antibody drug produced dramatic improvements in psoriasis patients.

In some cases, the improvements lasted up to six months after just one injection, researchers report.

"The studies that we carried out clearly showed that the drug worked, and worked very effectively," said study author Dr. Gerald G. Krueger, the Benning presidential endowed chair in the department of dermatology at the University of Utah. "I think this is going to be a very effective treatment if what we see in the phase 3 trial is similar to what we saw in this phase 2 trial. And there's no reason to believe it won't be."

The new study was instrumental in moving research forward to the phase 3 trial currently being conducted, Krueger added. That trial will provide more safety and efficacy data, probably in 2008.

"We still need to see the results of the phase 3 trial and some long-term safety data because it is a new drug, but patients in the trial have seen miraculous results," added Liz Horn, director of research at the National Psoriasis Foundation. "Some have had one injection and have stayed clear for quite a long time."

Psoriasis affects between 2 percent and 2.6 percent of Americans, or between 5.8 million and 7.5 million people. The disease occurs when the body suddenly begins overproducing skin cells. The cells pile up on the surface of the skin before they have a chance to mature, creating bright red patches covered with silvery scales.

These patches of skin cause itching, burning and stinging sensations. They most often occur on the elbows, knees, other parts of the legs, scalp, lower back, face, palms and soles of the feet. But they can occur on skin anywhere on the body, according to the U.S. National Institutes of Health.

Doctors believe the disease is linked to the immune system and is genetic in nature. But no one is certain why some people suffer from psoriasis while others do not, or what causes the disease to first start and then spread.