Progression pattern and post-progression survival following atezolizumab and bevacizumab treatment in advanced hepatocellular carcinoma.

539 Background: Although the combination of atezolizumab and bevacizumab (ATZ + BEV) is a standard treatment for advanced hepatocellular carcinoma (HCC), strategies for addressing treatment failure and prognostic factors of post-progression survival remain unestablished. Methods: We conducted a multicenter retrospective study to evaluate post-progression survival following ATZ + BEV treatment in patients with advanced HCC. We classified the patients into four groups: BCLC stage B with or without new intrahepatic lesions (BCLCp-B1 and BCLCp-B2, respectively) and BCLC stage C without or with new extrahepatic lesions (BCLCp-C1 and BCLCp-C2, respectively) at the time of progression. Results: Of the 204 patients who started ATZ + BEV treatment between October 2020 and September 2022, 110 showed disease progression, with 25, 8, 55, and 22 showing the BCLCp-B1, BCLCp-B2, BCLCp-C1, and BCLCp-C2 stages of the disease, respectively. Specifically, patients with the BCLCp-B1 stage of the disease showed better overall survival than those with the BCLCp-B2, BCLCp-C1, and BCLCp-C2 stages (hazard ratios: 2.19 (95% confidence interval [CI], 0.61–7.86), 2.16 (95% CI, 1.13–4.11), and 2.97 (95% CI, 1.42–6.23) for HCC stages BCLCp-B2, BCLCp-C1, and BCLCp-C2, respectively). Via multivariable analysis, we identified the BCLCp-C1 and BCLCp-C2 stages, as well as performance status, Child-Pugh class, and alpha-fetoprotein as poor prognostic factors for post-progression survival. Conclusions: BCLCp-B1 stage was identified as a better prognostic factor for post-progression survival following ATZ + BEV treatment compared with BCLCp-B2 stage as well as BCLCp-C1 and BCLCp-C2 stages. This may help in making decisions regarding subsequent treatment after ATZ + BEV.