Figure 3: Synergistic local direct and abscopal anti-tumor activity of PDT and immunotherapy.

a) Experimental design for the bilateral tumor model. C57BL/6 mice bearing BBN963 subcutaneous tumors at both flanks were used in this experiment. When tumors reached the size of around 100 mm³, tumors on the right side were treated with light for PDT and monitored for local direct anti-tumor activity. The tumors at the left flank were not treated with light and monitored for abscopal effects. b) In vivo fluorescence imaging to show PNP biodistribution at different time points of a C57BL/6 mouse bearing BBN963 tumors. Starting at 8 hours after administration, fluorescence from PNP accumulated at tumor sites with very little fluorescence at any other sites in the body. c) Tumor growth curves of the tumors at the right flank which were treated with light, showing the direct anti-tumor activities of PBS, anti-PD-1, PNP+L, or anti-PD-1+PNP+L (n=8). At day 25, compared to the control, the right-site-tumors (treated, direct anti-tumor effect) of the anti-PD-1, PDT and combination groups had a reduction of 40.25% (p=0.0003), 80.72% (p<0.0001) and 93.03% (p<0.0001), respectively. d) Tumor growth curves of the tumors at the left flank which were not treated with light, showing the abscopal anti-tumor activities. At Day 25, compared to the control, the tumor reduction of the left-site-tumors (measuring the abscopal effect) in the anti-PD-1, PDT and combination groups was 45.73% (p=0.0001), 54.92% (p<0.0001) and 75.96% (p<0.0001), respectively. The tumor reduction between the PDT with PNP and anti-PD-1 therapy groups was not statistically different (p=0.8402).