Similarly, treatment with a PDE5 inhibitor suppressed CD14+HLA-DR−/low MDSCs immunosuppressive activity and enhanced CIK activity against human HCC cell lines in vitro, suggesting targeting MDSCs is an efficient strategy to enhance the antitumor efficacy of CIKs for the treatment of patients with HCC. The gene discussed is PDE5A; the disease is hepatocellular carcinoma.