Methyl aminolevulinate plus photodynamic therapy shows promise as a treatment for severe acne vulgaris, according to a U.S. study published in the British Journal of Dermatology.
Dr. David M. Pariser of Eastern Virginia Medical School, Norfolk, and his associates conducted the randomized double-blind, vehicle-controlled trial of photodynamic therapy (PDT) with methyl aminolevulinate (MAL) as a photosensitizer in 153 males and females aged 12-35 years with severe facial acne. Inclusion criteria comprised an Investigator Global Assessment (IGA) rating score of 4, 20-100 noninflammatory lesions, and 25-75 inflammatory lesions with no more than three nodules (Br J Dermatol. 2015 December. doi: 10.1111/bjd.14345).
Participants received topical MAL 80 mg/g (100) or vehicle cream (53) and PDT every 2 weeks for four treatments, and were evaluated at each treatment and at 12 weeks. The MAL or vehicle cream was applied and covered for 1.5 hours, followed by PDT (635 nm of red light for a total dose of 37 J/cm2). Most completed the study (85% in MAL group and 91% in vehicle group).
Those in the MAL PDT group demonstrated a significant reduction in inflammatory lesions based on the percentage change at 12 weeks (a mean reduction of 37.3% vs. 16.2%; P = .003), and absolute change (a mean reduction of 15.6 lesions vs. 7.8; P = .006). However, the reduction in noninflammatory lesions was not significantly different between the two groups (a mean reduction of 11.8 lesions among those on MAL PDT vs. 10.7 with vehicle PDT) .
The rates of treatment success, defined as improvement of 2 or more IGA grades at 12 weeks, were higher among those in the MAL PDT group (44% vs. 26.4%; OR, 3.24; P = .013).
Pain scores were higher during PDT for the MAL group and remained similar with subsequent treatments. The MAL treatment was discontinued in six participants because of pain and PDT was paused briefly in 15 participants. More participants in the MAL group reported moderate erythema after the first PDT session (46% versus 15%) and three reported severe erythema.
The most commonly reported adverse events in the MAL treatment group were a sensation of skin burning and pain, mostly mild to moderate, lasting a median of 3 days. Further, 12% of those in the MAL group withdrew secondary to adverse events.
“This large, controlled randomized clinical study shows the potential of PDT using 80 mg/g MAL cream for treatment of severe acne” in patients aged 12 years and older, with all skin types, the authors concluded, noting that more follow-up data are needed on the duration of treatment response and long-term effect on scarring. “Severe acne has limited therapeutic options with problematic side effects and bacterial resistance and 80 mg/g MAL PDT could be an alternative approach with improved tolerability for these patients,” they added.
The authors noted that for severe cases of acne, treatment is limited, and while oral isotretinoin is often used, it is teratogenic, has side effects, and is associated with reimbursement difficulties.
Dr. Pariser and two colleagues disclosed receiving honoraria from Photocure ASA, which markets MAL as Visonac. The company funded the study.