Ce6-GFFY is a novel photosensitizer for colorectal cancer therapy.

Photodynamic therapy is an "old" strategy for cancer therapy featuring clinical safety and rapid working, but suitable photosensitizers for colorectal cancer therapy remain lacking. This study synthesized a novel photosensitizer termed Ce6-GFFY based on a self-assembling peptide GFFY and a photo-responsive molecule chlorin e6 (Ce6). Ce6-GFFY forms macroparticles with a diameter of ∼160 nm and possesses a half-life of 10 h, as well as an ideal tumor-targeting ability in mouse models. Ce6-GFFY effectively penetrates cells and generates numerous reactive oxygen species upon 660 nm laser irradiation. The reactive oxygen species promotes the accumulation of cytotoxic T cells and decrease of myeloid-derived suppressor cells in the tumor microenvironment through immunogenic cell death, thus prohibiting the growth of both primary and metastatic tumors after once treatment. This study not only provides a strategy for photosensitizer development but also confirms a promising application of Ce6-GFFY for colorectal cancer therapy.