Pseudoprogression in Hepatocellular Carcinoma During Atezolizumab Plus Bevacizumab Therapy: A Case Report and a Review of Literature.

Pseudoprogression is an atypical response pattern to immune checkpoint inhibitors (ICIs), characterized by initial tumor enlargement or the appearance of new lesions, followed by subsequent tumor regression. While this phenomenon has been observed in several solid tumors, its occurrence in hepatocellular carcinoma (HCC) is rare and not well understood, presenting diagnostic and therapeutic challenges. We report the first female case of HCC pseudoprogression during atezolizumab and bevacizumab therapy. The patient is a 63-year-old woman with chronic hepatitis B-related advanced HCC. After multiple prior treatments, she was started on combination therapy with atezolizumab and bevacizumab. Following four treatment cycles, imaging revealed tumor enlargement and new small lesions, suggestive of disease progression. However, her serum alpha-fetoprotein (AFP) level had decreased from 45,598 ng/mL to 23,719 ng/mL, and there was no clinical deterioration. Based on these findings, treatment was continued. Imaging after eight and 12 cycles demonstrated marked tumor regression and the normalization of AFP (<2 ng/mL), confirming a diagnosis of pseudoprogression. Although uncommon, pseudoprogression should be considered during ICI therapy for HCC. The accurate interpretation of radiologic findings in conjunction with clinical status and tumor markers is essential to avoid the premature discontinuation of potentially effective treatments. Further research is warranted to elucidate the underlying mechanisms, predictive markers, and clinical significance of pseudoprogression in HCC.