A pilot study indicates that the use of XTRAC excimer laser, already proven to be effective in treating mild to moderate cases of psoriasis, is effective in treating patients with moderate to severe psoriasis.
"Laser therapy has one big advantage over traditional phototherapy," says John Koo, M.D., professor and vice chairman of the University of California, San Francisco, department of dermatology and director of the study.
"That is, you're only delivering the light to the actual psoriasis. This allows much more aggressive and efficacious phototherapy, involving many times the minimal erythema doses (MED), since psoriasis plaques can tolerate much more than the noninvolved skin.
"The thing that's unique about this study, though, is that it's the first study ever conducted where we're using a laser for not just localized, but generalized, psoriasis. By generalized, we mean 10 to 20 percent," Dr. Koo tells Dermatology Times.
During a 12-week study period, patients received average twice-weekly treatments with the XTRAC excimer laser.
These patients exhibited typical moderate to severe psoriasis, with body surface area (BSA) of disease at 10 percent to 20 percent, and Fitzpatrick skin type greater than I.
The study concluded that, at week 12, 77 percent of those patients experienced greater than 75 percent improvement in their Psoriasis Area Severity Index (PASI) scores. Also, 44 percent of the patients had a greater than 90 percent improvement in PASI scores.
Most of the improvement occurred within the first 10 treatments with the XTRAC excimer laser, compared with the 30 to 40 treatments often needed for traditional phototherapy.
Despite this, Dr. Koo says, the study continued for 12 weeks in order to make the parameters similar to those in efficacy studies of other treatment options such as the biologics.
Based on these findings, the XTRAC excimer laser may be appropriate for a large proportion of patients with moderate to severe psoriasis.
The XTRAC laser has one of the highest UV power deliveries of any medical excimer laser on the market today for the treatment of psoriasis and vitiligo.
It is this ability to rapidly deliver high-power UV that allows for faster treatment of large surface areas.
Mei-Ling Pang, M.D., clinical psoriasis fellow at the University of California, San Francisco, conducted the study, and says that for the average patient, treatment with the XTRAC excimer laser may be a very attractive therapeutic choice.
"A patient who is obese, say over 250 pounds, may fall outside of that norm," she says. "Their body surface area is much larger.
"Also, patients who are a type I on the Fitzpatrick skin type have a tendency to burn very easily. So these patients might not tolerate the laser," Dr. Pang says.
Another area that might confound treatment is in patients with very thick and scaly plaques, as the nature of those plaques diffuses light, disrupting the effectiveness of any laser.
"That being said," Dr. Pang says, "I did have some success treating some of these more difficult psoriasis patients, especially in type III to type IV Fitzpatrick skin types, who are able to tolerate much higher doses of light. One gentleman, we actually used the laser dose at 4,500 mJ, and we cleared him. He stayed clear for several months."