Abstract B136: Development of PD-L1/L2 over-expressing mouse liver cancer models to test the efficacy of anti-PD1 therapy for hepatocellular carcinoma

Anti-PD1 therapy has shown promising anti-tumor activities in multiple cancer types, including hepatocellular carcinoma (HCC), and PD-L1 expression in tumor cells was considered a potential predictive marker for treatment efficacy. The present study explored whether PD-L1/L2 expression may affect treatment efficacy of anti-PD1 therapy for HCC. PD-L1 (MR203953; Origene Technologies, Rockville, MD) or PD-L2 (MR222499; Origene Technologies) was transfected into the BNL-MEA murine liver cancer cell lines and stable clones were selected. Effects of PDL1/L2 over-expression were confirmed by Western blotting and immunofluorescence assay. Effects of PDL1/L2 over-expression on in vitro growth characteristics were compared by MTT, colony formation, and 3-D culture assays. Orthotopic liver cancer models were established by sub-capsular injection of parental or transfected cancer cells into the left lobe of mouse liver. The anti-tumor efficacy of anti-mouse PD1 therapy (clone 4H2, Ono Pharmaceutical Co), 0.2 mg by intraperitoneal injection on day 5, 8, 11, 14, and 17 after tumor implantation, was measured by change in tumor volume using the orthotopic liver cancer models. Distribution of T-cell sub-populations in tumor-infiltrating lymphocytes (TILs) after treatment were measured by flow cytometry.

The growth characteristics of parental and PD-L1/L2-expressing BNL-MEA cells did not differ significantly, as measured by MTT, colony formation, and 3-D culture assays. Survival of animals bearing the orthotopic liver tumor with or without PD-L1/L2 over-expression was also similar. Anti-PD1 therapy appeared more efficacious in PD-L1-over-expressing liver cancer models than the parental or PD-L2-over-expressing models. Distinctive TILs distribution patterns between parental and PD-L1/L2 over-expressing liver cancer models were found after anti-PD1 therapy.

Conclusions: The PD-L1/L2 expressing liver cancer models may help evaluate the efficacy and mechanisms of action of anti-PD1 therapy for HCC.

Citation Format: Da-Liang Ou, Shu-Ching Chen, Yu-Chia Su, Ann-Lii Cheng, Chiun Hsu. Development of PD-L1/L2 over-expressing mouse liver cancer models to test the efficacy of anti-PD1 therapy for hepatocellular carcinoma. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B136.