Chlorin e6-Based Photodynamic Therapy for Metastatic Melanoma: An In Vitro Efficacy Study

Melanoma, the most aggressive form of skin cancer, remains incurable despite advances in treatment. Therefore, the need for alternative treatment approaches remains high. Photodynamic therapy is a localized, noninvasive treatment method. A photosensitizer is a crucial component of photodynamic therapy (PDT), which generates cytotoxic reactive oxygen species to kill cancer cells. A second-generation photosensitizer with FDA approval that satisfies the necessary clinical requirements for PDT is Chlorin e6 (Ce6). It is well-known for its strong anticancer effects on various cancer types and for its significant capacity to produce reactive oxygen species (ROS). Ce6 has demonstrated significant therapeutic potential against various cancers, including refractory ovarian, lung, melanoma, and metastatic breast cancer. In this study, we investigated the in vitro efficacy of Ce6-mediated photodynamic therapy (PDT) on metastatic melanoma (A375) cells, using a 660 nm laser at two different fluence levels (5 and 15 J/cm²) in 24 and 48 h. Cellular alterations were observed through ATP viability testing, microscopy examination, oxidative stress assessment, and cellular apoptosis assay during the study period. The results demonstrated that Ce6, when activated using the studied PDT parameters, effectively decreased cell viability and caused cell death by apoptosis, as seen by increased ROS generation in metastatic melanoma cells at both 5 J/cm² and 15 J/cm² PDT doses. Our study confirmed that the therapeutic potential of Ce6 supports its suitability as a promising photosensitizer for incorporation into a nanobioconjugate platform for the treatment of melanoma.