Locally Administered Photothermal Therapy for Breast Cancer using Endolysosome-Targeted Indocyanine Green Conjugated with Polycation

Author(s): Saori Fujiwara, Toru Yoshitomi, Aoi Hoshi, Van Thi Hong Doan, Yoshiki Komatsu, Huajian Chen, Naoki Kawazoe, Guoping Chen, Azusa Terasaki, Hiroko Bando, Hisato Hara, and Hirofumi Matsui.

Near-infrared photothermal therapy using indocyanine green has a great potential of anti-tumor therapy against deep tumor tissue owing to its biological transparency window and high spatiotemporal selectivity. However, even intratumor administration of indocyanine green does not show high antitumor efficacy. To improve the anti-tumor efficacy of indocyanine green, in this study, we have developed a locally administered photothermal therapy using indocyanine green with polycations bearing quaternary ammonium salt groups, referred to as aICG. The aICG was accumulated in endolysosome via endocytosis after cell adhesion by electrostatic interaction, and induced apoptosis by laser irradiation at 808 nm, while low-molecular-weight ICG distributed in the cytoplasm. Photothermal therapy with intratumor injection of aICG showed a higher anti-tumor effect upon the light irradiation at 808 nm, compared to low-molecular-weight ICG. In addition, the treatment with aICG did not cause any adverse effects such as weight loss, and hepatic and renal dysfunctions. Therefore, aICG has a potential as photothermal agent for locally administered photothermal therapy.