Rose Bengal–Amphiphilic Peptide Conjugate for Enhanced Photodynamic Therapy of Malignant Melanoma

Malignant melanoma is an aggressive
skin cancer with poor survival
outcomes for patients diagnosed at an advanced stage. While targeted
serine/threonine-protein kinase B-Raf (BRAF) and immune checkpoint
inhibitors have improved survival outcomes for a proportion of these
patients, response rates remain variable. There is a need, therefore,
for more effective treatments to bolster the options available for
melanoma patients. In this manuscript, we covalently attached Rose
Bengal (RB) to the amphipathic peptide (AMP) C­(KLAKLAK)2 and determined the effectiveness of the resulting RB-C­(KLAKLAK)2 conjugate as a photodynamic therapy (PDT) sensitizer. RB-C­(KLAKLAK)2-mediated PDT treatment of subcutaneous B16-F10-Luc2 tumors
in C57 mice resulted in lesions that were 479% smaller at the end
of the study than animals treated with RB-mediated PDT. The synergistic
effect between RB and C­(KLAKLAK)2 has been attributed to
the AMP sensitizing cells to reactive oxygen species (ROS), making
them more susceptible to ROS-induced oxidative stress.