Epigenetic modulation enhances immunotherapy for hepatocellular carcinoma

Area of Science:

• Oncology
• Immunology
• Epigenetics

Background:

• Hepatocellular Carcinoma (HCC) exhibits a mixed response to anti-PDL-1 immunotherapy.
• Polycomb Repressor Complex 2 (PRC2), involving EZH2 and DNMT1, promotes HCC by suppressing tumor antigens and immune response.
• Targeting EZH2 and DNMT1 may enhance HCC immunotherapy efficacy.

Purpose of the Study:

• To investigate the potential of epigenetic therapy targeting EZH2 and DNMT1 to modulate immunotherapy response in HCC.
• To evaluate the combined effect of EZH2/DNMT1 inhibitors and anti-PDL-1 on HCC cell lines and in vivo models.

Main Methods:

• HCC cell lines (HepG2, Hep3B, Hepa1-6) were treated with EZH2 inhibitor (DZNep) and DNMT1 inhibitor (5-Azacytidine), with and without anti-PDL-1.
• Gene expression (tumor suppressors, antigens, Th1 chemokines) was assessed using qRT-PCR and immunohistochemistry.
• An in vivo immunocompetent mice model was used to evaluate tumor regression and immune cell trafficking.

Main Results:

• Combination therapy significantly upregulated Th1 chemokines (CXCL9, CXCL10) and induced cancer-testis antigens (NY-ESO-1, LAGE).
• In vivo studies showed significant tumor regression with combination therapy compared to monotherapies or control.
• Enhanced cytotoxic T-lymphocyte trafficking and apoptosis were observed in the combination treatment group.

Conclusions:

• Epigenetic modulation targeting EZH2 and DNMT1 can augment HCC immunotherapy.
• This strategy stimulates T cell trafficking and neoantigen presentation, leading to tumor regression.
• A clinical trial evaluating this combination therapy is warranted.