Durable disease control in unresectable hepatocellular carcinoma with atezolizumab plus half-dose bevacizumab: pathological complete response of peritoneal metastasis.

backgroundAtezolizumab plus bevacizumab (ATZ + BV) is the standard first-line therapy for unresectable hepatocellular carcinoma (HCC). However, long-term treatment is frequently limited by adverse events such as proteinuria and hypertension, often resulting in treatment interruption or discontinuation. Evidence regarding the feasibility of dose modification, particularly half-dose BV, remains limited. CASE PRESENTATION: We report a patient with unresectable HCC who responded favorably to ATZ + BV but developed significant proteinuria (> 2 g/day) after several cycles. To manage this toxicity, BV was reduced to half the standard dose while continuing full-dose ATZ. Following dose modification, proteinuria stabilized, and systemic therapy was maintained for more than 3 years. During follow-up, the patient underwent gastrectomy for gastric cancer, at which time a peritoneal metastatic lesion of HCC was also resected. Histopathological examination revealed complete absence of viable tumor cells, confirming a pathological complete response (pCR). Of note, in our institutional experience with more than 70 patients treated with ATZ + BV, several also required BV half-dose, and long-term disease control was observed, supporting the reproducibility of this approach.

conclusionThis case suggests that reducing the BV dose to half of the standard level may allow continued ATZ + BV therapy without loss of efficacy. Furthermore, the achievement of pCR in a resected peritoneal metastasis underscores the potential of this management strategy for durable disease control in unresectable HCC.