Organ-specific responses to atezolizumab plus bevacizumab in advanced hepatocellular carcinoma: A multicentre, retrospective study

Background and Aims Anti-programmed death 1 (PD-1) monotherapy triggers various responses by each organ. In advanced hepatocellular carcinoma (HCC), while extrahepatic lesions demonstrate objective response rates (ORR) of 20%-40%, only 10% of intrahepatic lesions respond. Although first-line atezolizumab/bevacizumab has shown survival benefits in advanced HCC, organ-specific responses remain unexplored. Therefore, we aimed to assess organ-specific responses in patients with advanced HCC receiving atezolizumab/bevacizumab. Methods This retrospective, multicenter, observational study included patients who received first-line atezolizumab/bevacizumab for advanced HCC. Patients with Child-Pugh class A, measurable tumour lesions and serial imaging available for response evaluation were eligible. Results Between May 2020 and June 2021, 131 patients (median age: 62) from three cancer referral institutions were included. Ninety-one had hepatitis B (69.5%), 108 were at Barcelona clinic liver cancer stage C (82.4%), and 78 had extrahepatic metastasis (59.5%). After a median follow-up of 10.1 months, median progression-free survival was 6.8 months (95% confidence interval [CI], 4.6-9.2), median overall survival remained unreached (95% CI, range unavailable) and the ORR was 29.0%. Among 270 individual tumour lesions, the liver was the most commonly involved organ (n = 158). Atezolizumab/bevacizumab induced ORR of 27.8%, 42.2%, 29.1% and 21.0% for liver, lymph nodes, lungs and other sites, respectively. The organ-specific response rate for intrahepatic tumours decreased with increasing size (35.6%: <5 cm, 15.0%: >= 5 cm). Conclusions Unlike anti-PD-1 monotherapy, atezolizumab/bevacizumab demonstrated favourable responses in intrahepatic lesions, comparable to those in extrahepatic lesions, and may potentially overcome the immune-tolerant hepatic microenvironment in patients with advanced HCC.