Systemic Antitumor Immunity by PD-1/PD-L1 Inhibition Is Potentiated by Vascular-Targeted Photodynamic Therapy of Primary Tumors.

PD-1/PD-L1 pathway inhibition is effective against advanced renal cell carcinoma, although results are variable and may depend on host factors, including the tumor microenvironment. Vascular-targeted photodynamic (VTP) therapy with the photosensitizer WST11 induces a defined local immune response, and we sought to determine whether this could potentiate the local and systemic antitumor response to PD-1 pathway inhibition. Using an orthotopic Renca murine model of renal cell carcinoma that develops lung metastases, we treated primary renal tumors with either VTP alone, PD-1/PD-L1 antagonistic antibodies alone, or a combination of VTP and antibodies and then examined treatment responses, including immune infiltration in primary and metastatic sites.