Research Progress in Alpha-fetoprotein-induced Immunosuppression of Liver Cancer

Liver cancer is one of the most common malignant tumors, with limited treatment and 8.2% mortality. Liver cancer is the fourth leading cause of cancer-related deaths, which seriously endangers human life and health. Approximately 70% of liver cancer patients show increased serum Alpha- Fetoprotein (AFP) levels. AFP is the main diagnostic and prognostic indicator of liver cancer. AFP, a key marker of liver cancer, plays a crucial role in regulating the proliferation of tumor cells, apoptosis, and induction of cellular immune escape. High levels of AFP during embryonic development protect the embryos from maternal immune attack. AFP also promotes immune escape of liver cancer cells by inhibiting Tumor-Infiltrating Lymphocytes (TILs), Natural Killer cells (NK), Dendritic Cells (DC), and macrophages; thus, it is also used as a target antigen in immunotherapy for liver cancer. AFP is highly expressed in liver cancer cells. In addition to being used in the diagnosis of liver cancer, it has become a target of immunotherapy for liver cancer as a tumor-associated antigen. In immunotherapy, it was also confirmed that early AFP response was positively correlated with the efficacy of immunotherapy. Early AFP responders had longer PFS and OS than non-responders. At present, the methods of immunotherapy for liver cancer mainly include Adoptive Cell Transfer Therapy (ACT), tumor vaccine therapy, immune checkpoint inhibitors (ICIs) therapy, etc. A large number of studies have shown that AFP mainly plays a role in ACT and liver cancer vaccines. This review presents the research progress of AFP and immunosuppression of liver cancer.