Roger Ceilley, MD took us through a riveting review of the innovations in photodynamic therapy but not before completing an overview of its mechanism of action and some industry updates for clinical practice. Notably, a new red light laser (635nm) has garnered FDA approval with a flexible multipanel lamp for full face coverage, and CPT codes strictly dictate clinician involvement in PDT procedure: 96567 for no direct participation, 96573 for clinicians applying photosensitizer and initiating light illumination, and 96574 for the performance of curettage or debridement prior to PDT. 

He emphasized the importance of setting expectations, especially surrounding one of the major disadvantages of PDT which is the discomfort and erythema that remains post-procedure.  While compliance with PDT remains much higher than that for topicals in the treatment of actinic keratoses, Dr. Ceilley proposed multiple methods to mediate patient discomfort. One split-face study that compared blue light PDT with two photosensitizers, 10% ALA-gel and 20% ALA solution, demonstrated that the gel formulation was associated with significantly less local skin reactions. Other options to mitigate pain include fans, cold compresses, antihistamines, and topical or local anesthesia, though modifications to the actual treatment regimen, i.e. shorter incubation times or lower irradiance, may be the most effective. Even immediate irradiance, “simultaneous PDT”, for 30 – 60 minutes after application of ALA could be a promising option to dramatically lower pain scores while maintaining almost identical clearance rates to conventional PDT in another, albeit small (n=23), split-face study. 

Moving on to treating the extremities and trunk, Dr. Ceilley showed that efficacy can be increased with the addition of occlusion dressing during the incubation period or with pretreatment of adapalene for 7 days in two RCT trials. Microneedling prior to treatment with ALA appeared to have less dramatic results, with improved AK clearance after 20-minute incubation but not for 10-minute incubation. While simultaneous PDT may be effective for the face, he recommended sticking to an incubation time of at least 2-3 hours for the extremities. Other tricks to increase efficacy of PDT include adding cryotherapy before incubation and warming the extremities before irradiance, called “thermal” PDT. New frontiers include the use of PDT for alternative conditions like photodamage, which has already shown promising results, inflammatory conditions like acne and psoriasis, and cutaneous T-cell lymphoma.