A randomized split-scalp study comparing Calcipotriol assisted MAL-PDT with Conventional MAL-PDT for the treatment of Actinic Keratosis

Summary

Background

Topical photodynamic therapy (PDT) is an approved treatment for actinic keratosis (AK). To enhance the efficacy of PDT for AKs, physical (ablative lasers and microneedling) and chemical (pro-differentiating drugs) pretreatments have been suggested.

Objectives

To compare the efficacy and safety of the combination of topical calcipotriol (CAL) before methylaminolevulinate (MAL)-PDT for AKs of the scalp versus conventional MAL-PDT in a randomized controlled-clinical trial.

Materials and Methods

Twenty patients with multiple AKs on the scalp were randomized to receive conventional MAL - PDT with previous curettage on one side of the scalp and CAL – assisted MAL-PDT applied once a day for fifteen days before the illumination with red light-emitting diode (37J/cm²) on the other side. After three months, patients were evaluated for the clearance of AKs, side effects and histopathology before and after the procedure. Protoporphyrin IX (PpIX) fluorescence was measured before and after illumination on both sides.

Results

All twenty patients completed the study. Overall AK clearance was 92.07% and 82.04% for CAL-PDT and conventional PDT respectively (p< 0.001). The AKs grade I showed similar response rate of 92.83% and 87.29% (p=0.055) respectively for CAL and MAL-PDT sides. However, AKs grade II showed more improvement on the CAL-PDT side (89.55%) compared with MAL-PDT (62.90%) (p<0.001). Before illumination, PpIX fluorescence intensity was higher on the CAL-assisted side (p=0.048). The treatment was more painful on the CAL-PDT side, although well tolerated. The mean VAS score was 5.40±1.43 on the CAL-PDT side and 3.95±0.69 on the conventional MAL-PDT side (p=0.001). Side effects such as erythema (p=0.019), edema (p=0.002), crusts (p<0.001) were more pronounced on the CAL-assisted side. Histopathological analyses were obtained from five patients and both sides showed improved keratinocyte atypia following PDT, with a slight more improvement on CAL- assisted side.

Conclusion

CAL-assisted PDT proved to be safe and more effective than conventional MAL-PDT for the treatment of AKs on the scalp. CAL pretreatment increased PpIX accumulation within the skin and may have enhanced the efficacy in this first human trial. As this is the first CAL-assisted PDT study in human skin, further and larger trials are needed to corroborate our findings.

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