Near-infrared photoimmunotherapy for effective elimination of ovarian cancer cells by inducing immunogenic cell death.

Ovarian cancer represents one of the most common forms of female gynecological cancer. The existing treatment modalities include surgery and chemotherapy, which are unable to treat local and long-distant micro-metastases. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed treatment strategy that can selectively kill the cancer cells and induce immunogenic cell death and thereby stimulate anti-tumor immune responses. In this study, we developed five NIR-PIT agents by conjugating scFv-SNAP-tag fusion proteins with BG-modified IRdye700 to target ovarian cancer cells, which expressed cell surface antigens epidermal growth factor receptor (EGFR), Her2, FOLR1, TROP2, and TF. Flow cytometry and microscopic studies confirmed the specificity of all the investigated NIR-PIT agents binding to corresponding overexpressed cancer cells. In addition, all the investigated NIR-PIT agents demonstrate specific binding to human ovarian cancer tissues, as confirmed by multiplex immunofluorescence imaging. We validated that all five NIR-PIT agents decreased the cell viability in a concentration-dependent manner with IC(50) values of ∼42-283 nM. Moreover, all examined NIR-PIT agents induced cell death with efficiencies of ∼80%-92%. The NIR-PIT agents triggered major hallmarks of immunogenic cell death like cell surface expression of calreticulin, HSP70, and HSP90 and the extracellular release of ATP and HMGB1. Furthermore, co-culturing immature dendritic cells with dying cancer cells targeted by EGFR and TF NIR-PIT agents mediated enhanced dendritic cell maturation, as indicated by increased expression of CD80, CD86, CD40, and HLADR. Taken together, our results suggested that all five investigated NIR-PIT agents have great potential to be applicable for ovarian cancer treatment.