ALA-PDT most effective with bluelight, study shows

May 1, 2006

San Francisco - Interim results of a phase 2,vehicle-controlled, bilateral study evaluating the efficacy andsafety of broad area topical 5-aminolevulenic acid (ALA, LevulanKerastick, DUSA Pharmaceuticals) photodynamic therapy (PDT) withvarious light sources show that ALA plus blue light (BLU-U, DUSAPharmaceuticals) was significantly more effective than vehicle plusblue light in improving facial photodamage, but the statisticalanalyses did not find ALA pretreatment enhanced the benefitsachieved using an intense pulsed light source (IPL; Quantum,Lumenis) or a pulsed dye laser (PDL; VStar, Cynosure), said RobertA. Weiss, M.D., associate professor of dermatology, Johns HopkinsUniversity School of Medicine, Baltimore, and an investigator inthe phase 2 trial.

"Clinically, there were some nice improvements with ALA-PDT for all light sources, especially with regard to reduction in pigmentation and actinic keratoses, as well as some noticeable differences comparing those facial halves with the vehicle-treated sides. In regard to the latter, the results of the statistical analyses evaluating the effects of ALA-PDT with the IPL and PDL are in contradiction to our general clinical experience where use of ALA seems to augment the treatment benefits using those light sources, and the reason for that discrepancy is not clear," Dr. Weiss says. He discussed the results in a poster session at the 64th Annual Meeting of the American Academy of Dermatology.

"This study was not designed to detect significant differences in responses to the various light sources. However, it is worth noting that ALA-PDT with blue light provided outcomes comparable to those achieved with IPL or PDL. Considering its tolerability and the ease of use for blue light treatment compared with IPL or PDL, further investigations are warranted," Dr. Weiss says.

Study specifics

The study had a multicenter, randomized, evaluator-blinded design and enrolled 60 subjects with Fitzpatrick skin phototypes I to III who had symmetric mild to moderate facial photodamage and fine wrinkling and mottled pigmentation scores of 2 or 3 on a rating scale of 0 (none) to 4 (severe). They were randomized equally among the three light sources, and each patient was randomized to undergo treatment with topical ALA on one side of the face and vehicle contralaterally.

Fluences used for the light treatments were 5 J/cm2 (delivered at 10 mW/cm2 ) for blue light, 7±0.5 J/cm2 (two passes) for PDL, and 25±2 J/cm2 for IPL. Light dosing for PDL and IPL were determined in an initial phase of the study, while the blue light dose was chosen based on historical experience. The incubation time for ALA was 60±15 minutes.

Depending on tolerability, patients could receive up to three treatments, performed once every three weeks.

Responses were evaluated at 48 hours after each treatment and again at weeks nine and 12 by the blinded investigator using a 5-point scale to rate overall appearance (Investigator's Global Photodamage Score) and severity of individual signs, including fine wrinkles, mottled pigmentation, tactile roughness, sallowness and telangiectasias. Longer-term follow-up at 26 weeks and 52 weeks is planned.

"Consistent with previous experience with these treatments and other forms of skin rejuvenation stimulating collagen remodeling, the results in this study showed continued improvement between nine weeks and 12 weeks for all light sources," Dr. Weiss says.