Light Dose Ranging Study of Photodynamic Therapy (PDT) With Levulan + Blue Light Versus Vehicle + Blue Light in Severe Facial Acne

This is a Phase II multicenter, randomized, evaluator-blinded, vehicle-controlled, parallel group light dose ranging study of photodynamic therapy in subjects with moderate to severe facial acne vulgaris. Subjects will be randomized to one of the following four treatment groups (1:1:1:1) to receive topical Levulan® Kerastick® containing 20% aminolevulinic acid HCL (ALA, active study drug) or the Kerastick® containing vehicle ingredients only (VEH). * Group 1 will have ALA applied to the entire facial area 45 minutes ± 15 minutes prior to BLUE light treatment for 1000 seconds (16 minutes 40 seconds) * Group 2 will have ALA applied to the entire facial area 45 minutes ± 15 minutes prior to BLUE light treatment for 500 seconds (8 minutes 20 seconds) * Group 3 will have VEH applied to the entire facial area 45 minutes ± 15 minutes prior to BLUE light treatment for 1000 seconds (16 minutes 40 seconds) * Group 4 will have VEH applied to the entire facial area 45 minutes ± 15 minutes prior to BLUE light treatment for 500 seconds (8 minutes 20 seconds) Each subject may receive up to four treatments at three week (± 2 days) intervals. The power density (dose rate) and the total fluence (light dose) used at each treatment is intended to remain constant throughout each subject's participation. If a subject meets or exceeds the criteria restricting retreatment (CRR) prior to retreatment (Section 5.6), he/she will not receive additional PDT treatment at that visit and will be asked to return for the next scheduled PDT visit 3 weeks later, if applicable. Post-treatment follow-up visits will be scheduled to occur at 3 and 6 weeks after the subject's final PDT. Grading of the subject's facial acne will be conducted by a blinded evaluator who will remain blinded with respect to the subject's treatment assignment. Tolerability of treatment will be assessed by evaluations of the local skin response (erythema, edema, etc.) and will be conducted by an unblinded evaluator. Safety will be evaluated by adverse events and local skin responses reported during the study.