Polysaccharide and PD1-Antibody Combination Therapy Enhances Antitumor Efficacy in Colorectal Cancer-Xenograft Mice.

Objective: To observe the efficacy of polysaccharide (AEPS) combined with PD1 antibody therapy in colorectal cancer-xenograft mice.

Methods: CT26 cells were inoculated into 80 C57BL/6 mice to establish the colorectal cancer xenograft-mouse model. Mice were divided evenly into a model group, AEPS group, anti-PD1 group, and combined group. AEPS 5mL/kg•day was given orally and 10 mg/kg anti-PD1 injected intravenously for 28 days. Tumor growth and mouse survival were observed. Tumor-cell proliferation and metastasis markers Ki67, N-cadherin, KLF4, and Oct4 were detected with immunochemistry and Western blotting, T-cell infiltration in spleens and tumors was detected with MTT and flow cytometry. IFNγ and TNFα were detected with ELISA.

Results: Tumor growth was significantly retarded and survival prolonged in the AEPS, anti-PD1, and combined groups. Ki67 expression decreased in the anti-PD1 and combined groups, and N-cadherin, KLF4, and Oct4 expression decreased in the AEPS and combined groups. IFNγ and TNFα levels, T-cell infiltration in spleen, and tumor all increased distinctively in the AEPS and combined groups. The combined group showed better antitumor effects and life-extension effect than the other two groups.

Conclusion: AEPS and PD1 antibody-combination therapy can suppresses tumor growth and prolong survival of colorectal cancer-xenograft mice by regulating immunofunction, and the combined therapy showed better therapeutic efficacy than the single treatment.