Effect of Expedited Microneedle-Assisted Photodynamic Therapy for Field Treatment of Actinic Keratoses: A Randomized Clinical Trial.

Importance: Photodynamic therapy (PDT) is an effective and cosmetically favorable treatment modality for actinic keratoses (AKs). However, prolonged incubation times and pain associated with treatment are burdensome to the patient and a hindrance to widespread use of PDT as standard field therapy for AK.

Objective: To evaluate efficacy and pain associated with microneedle expedited PDT.

Design, Setting, and Participants: The Microneedle Photodynamic Therapy II (MNPDT-II) study was a randomized, single-blinded, split-face controlled, 2-arm clinical trial. Thirty-three participants with AK on the face were recruited in a university dermatology outpatient clinic from 2015 to 2016, and 32 participants completed the study.

Interventions: Participants were randomized into 2 incubations arms, either 10-minute or 20-minute aminolevulinic acid (ALA) incubation times, after pretreatment with a microneedle roller (200 um) vs a sham roller. They were blinded to the laterality of microneedle and sham roller assignments. After incubation, they were exposed to blue light (Blu-U, Dusa Pharmaceuticals) for 1000 seconds for a total fluence of 10 J/cm2.

Main Outcomes and Measures: The primary outcome was to quantitatively measure AK resolution, and the secondary outcome was to assess pain associated with microneedle pretreatment.

Results: Thirty-three individuals were recruited and randomized to either the 20-minute or the 10-minute incubation arm. Thirty-two participants completed the study with a mean follow-up time of 34.5 days in the 20-minute group, and 30.2 days in the 10-minute group. For the 20-minute incubation arm, average AK clearance was 76% vs 58% on the sham side (P < .01), including 3 patients with complete clearance, although not statistically significant (P = .25). Pain assessment on the visual analog scale (VAS) during blue light illumination was not significantly different between the microneedle and sham sides (0.7 and 0.4; P = .28), respectively. For the 10-minute incubation arm AK clearance for the microneedle pretreated side was 43% compared with 38% on the sham side (P = .66). Pain during the blue light exposure was not significantly different between the microneedle and sham sides, 4.5 mm and 3.4 mm (P = .21), respectively.

Conclusions and Relevance: Photodynamic therapy with microneedle pretreatment at a 20-minute ALA incubation time significantly improved AK clearance with efficacy similar to that of a conventional 1-hour ALA incubation time. The additional advantage to expedited treatment was that the procedure was virtually painless. However, expedited exposure of a 10-minute ALA incubation time did not reach significantly different AK clearance from the sham control.

Trial Registration: clinicaltrials.gov Identifier: NCT02594644.