Hepatocellular Carcinoma Pseudoprogression Involving the Main Portal Vein, Right Ventricular Invasion, and Exacerbation of Lung Metastases in a Patient on Atezolizumab Plus Bevacizumab.

A 70-year-old man was diagnosed with hepatocellular carcinoma (HCC) with portal vein invasion and lung metastases, for which atezolizumab plus bevacizumab (ATZ/BEV) was initiated. After two months, computed tomography revealed tumor growth accompanied by ascites, right ventricular invasion, exacerbation of the lung metastases, and main portal vein invasion. However, continuation of ATZ/BEV caused remarkable size reductions in all lesions, finally resulting in the disappearance of the vascular invasion and lung metastases after nine cycles of treatment. The tumor growth was considered to reflect pseudoprogression, which is difficult to distinguish from hyperprogression. We herein report a remarkable HCC case of pseudoprogression on ATZ/BEV.