Synergistic effect of OK-432 in combination with an anti-PD-1 antibody for residual tumors after radiofrequency ablation of hepatocellular carcinoma

BACKGROUND AND AIMS: Radiofrequency ablation (RFA) often results in incomplete ablation for medium-to-large and irregular tumors. To solve this clinical problem, we proposed a new treatment strategy of OK-432 in combination with an anti-programmed cell death protein 1 (αPD-1) antibody for residual tumors after incomplete RFA (iRFA) of hepatocellular carcinoma (HCC). APPROACH AND RESULTS: regulatory T cells in residual tumors after iRFA of HCC. Moreover, the smallest tumor volumes and the longest survival were observed in the triple combination treatment (iRFA+OK-432 +αPD-1 antibody) group compared with the other four groups. CONCLUSIONS: The combined therapy of OK-432 with αPD-1 antibody induced a strong antitumor immune response, which significantly inhibited the residual tumors after iRFA of HCC. This concept may provide a new treatment strategy to increase the curative efficacy of RFA for medium-to-large and irregular HCCs. AVAILABILITY OF DATA AND MATERIAL: The data of this study are available from the corresponding author on reasonable request.