Figure 6.
Antitumor Effects of Combination Therapy in a CT26 Orthotopic Rectal Tumor Model with Liver Metastases
(A) Study protocol. In brief, in the CT26-Luc orthotopic rectal tumor model with liver metastases, CT26-Luc rectal tumors were treated with OBP-502 (1 × 109 PFUs) intratumorally and PD-1 Ab (1st: 20 mg/kg, 2nd and 3rd: 10 mg/kg) intraperitoneally three times each week. (B) Kaplan-Meier survival analysis (n = 8). *p < 0.05. (C) Representative IVIS images of mice 28 days after initiation of treatment with PBS, monotherapy with OBP-502 or PD-1 Ab, or combination of both. (D and E) Luminescence intensity of rectal tumors (D) and liver metastases (E) was measured using the IVIS imaging system on day 21 (n = 8). *p < 0.05, **p < 0.001. (F and G) Macroscopic findings (F) and H&E staining (G) of liver metastases harvested 14 days after initiation of treatment with PBS, monotherapy with OBP-502 or PD-1 Ab, or combination of both (twice, on days 0 and 7). Scale bar, 20 μm.