Figure 5.

Combination therapy with CIRT and anti-PD-1 increases overall survival of melanoma-bearing mice. C57BL/6 mice bearing subcutaneous B16 and S91 melanoma (Model) were injected intraperitoneally with anti-PD-1 (α-PD-1) or locally irradiated with 5 Gy of X-rays (XR) or 5 GyE of carbon ions (CIRT) at tumor sites or underwent a combined treatment with 5 Gy of X-rays and anti-PD-1 (XR+α-PD-1) or 5 GyE of carbon ions and anti-PD-1 (CIRT+α-PD-1). Anti-PD-1 was injected intraperitoneally on days 2, 4, and 6 after irradiation. All treatments slowed the tumor growth rate. Tumor volume and survival ratio of the mice were measured every second day from the day of irradiation until the tumor volume reached the endpoint (2000 mm³). Representative images and quantification are shown (mean ± SD of triplicate assessments, Student’s t test, ***p < .001).