Unexpected anti-tumor effect of immune checkpoint inhibitors followed by transcatheter arterial chemoembolization for hepatocellular carcinoma

The abscopal effect has recently attracted much attention because this effect is enhanced by immune checkpoint inhibitors (ICIs). However, little is known about the association between induction of the abscopal effect and local treatment against hepatocellular carcinoma (HCC). We describe a patient with advanced HCC who underwent selective transcatheter arterial chemoembolization (TACE) after treatment with an ICI that was found to remarkably regress in lesions in areas outside that targeted by selective TACE. An 82-year-old man had multiple recurrences in both lobes of the liver despite of repeated TACE and radiofrequency ablation, after resection of an HCC five years previously. After chemotherapy with atezolizumab and bevacizumab, his des-gamma-carboxy prothrombin (DCP) increased. CT during hepatic arteriography revealed multiple recurrent HCCs in both lobes of the liver. TACE with selective embolization at the level of the medial segmental arteries was performed against an approximately 50 mm-diameter tumor in the right lobe. Hepatic arterial phase imaging of contrast-enhanced CT performed 6 days after TACE showed hypo-enhancement of tumors in segment II and III in the left lobe. This case highlights that abscopal effects can be induced by local treatment against HCCs in combination with treatment with ICIs.