Synergistic effects of AAGL and anti-PD-1 on hepatocellular carcinoma through lymphocyte recruitment to the liver.

Objective: Therapy for hepatocellular carcinoma (HCC) is a major challenge, and targeted therapies provide only a modest benefitin terms of overall survival. Treatment with antibodies to programmed cell death protein 1 (PD-1)/PD-L1 can restore the functionsof tumor-infiltrating T cells in HCC and has shown clinical efficacy in 20% of patients with advanced HCC. Novel approaches areurgently needed to treat HCC and to augment the efficacy of immunotherapy. Methods: Tumor-bearing mice were treated with Agrocybe aegerita galectin (AAGL) alone or in combination with anti-PD-1, and thetumor sizes and lifespans of mice were determined. Transcriptome analysis, cytokine analysis, flow cytometry analysis of the numberand proportion of immune cell subsets in the liver and spleen, and molecular and cellular analyses of tumors were used to define theunderlying mechanisms. Results: AAGL significantly inhibited the growth of liver tumors in a dose-dependent manner. Furthermore, AAGL increased theexpression of multiple cytokines and chemokines in tumor-bearing mouse livers; this effect was associated with the activation andmigration of T cells and macrophages, in agreement with the in vitro results. Importantly, the aggregation of T cells and macrophagesinduced by AAGL in tumor-bearing mouse livers clearly enhanced the response to PD-1 blockade immunotherapy. Conclusions: The results showed that AAGL induced the activation and migration of lymphocytes to the liver, and that thecombination of AAGL and anti-PD-1 may be a promising strategy for HCC treatment.