Immunotherapy of hepatocellular carcinoma: is there a place for regulatory T-lymphocyte depletion?

Immunotherapy represents a potential therapeutic option for patients with hepatocellular carcinoma (HCC), especially as secondary treatment to prevent recurrence. It has been shown that a patient's survival is directly correlated to the type and number of tumor-infiltrating immune cells, indicating that immune responses have a direct effect on the clinical course of the disease. We have assessed the potential of immunotherapy against HCC in preclinical models of low tumor burden. An antigen-specific strategy targeting alpha-fetoprotein, and consisting of immunization with a DNA-based synthetic vector (DNAmAFP/704), was tested on an autochthonous model of chemical hepatocarcinogenesis and led to an important (65%) reduction of the tumor burden. A nonspecific approach of CD25(+) T-cell depletion by injection of PC61 antibody was also tested on an orthotopic HCC model and led to a significant protection against tumor development. Antigen-specific immunotherapy and Treg depletion are promising strategies in physiologically relevant HCC preclinical models. Future clinical trials will demonstrate if a combination of Treg depletion with an antigen-specific immunotherapy will also translate into clinical responses in HCC patients.