New Approaches to Photodynamic Therapy of Melanomas

We present new approaches to treat both primary cutaneous and ocular melanoma, with potential to reduce metastatic spread In mouse models optical clearing combined with dual-photosensitizer PDT is used to treat primary cutaneous xenogafts. Two-photon PDT is used in ocular melanoma of extraocular (conjunctival) or intraocular (uveal) melanoma. Immune effects are investigated in immunocompetent mice using blood biomarkers and by tumor re-challenge. In vitro studies in pigmented and non-pigmented melanoma cells show melanin-mediated photosensitization as a novel mechanism of action of 2-γ PDT. Full-thickness primary tumor eradication has been achieved: ∼1 and 4 mm in immune deficient and competent mice, respectively. Marked reduction in metastatic tumor burden is observed in the latter. These studies reopen the possibility of PDT as an effective modality in melanoma.