Long-term survival outcomes of atezolizumab plus bevacizumab treatment in patients with advanced hepatocellular carcinoma.

600 Background: Immunotherapy combinations such as atezolizumab plus bevacizumab (Atezo-Bev) or STRIDE have been established as standard therapies for patients with advanced hepatocellular carcinoma (HCC). After dual immunotherapy treatment, durable responders and long-term survivors had been reported. However, the longevity of such outcomes following Atezo-Bev treatment remains to be evaluated. Methods: We analyzed medical records of four medical centers in Taiwan for patients with Child-Pugh class A liver reserve who received first-line Atezo-Bev treatment for advanced HCC from January 2018 to May 2021, to evaluate their survival outcomes after a long-term follow-up. Results: We enrolled 54 patients, predominantly male (90.7%) with the median age of 65 years. The main hepatitis etiology was viral hepatitis (92.6%), including 68.5% chronic hepatitis B. After a median follow-up of 61.9 months, the median overall survival (OS) was 21.0 months (95% confidence interval 10.4 – 31.6 months). The 3-year, 4-year and 5-year OS rate was 36.4%, 25.7% and 25.7%, respectively. For patients with tumor response (N = 19, 34.5%) or disease control (N = 44, 80.0%), the 3-year, 4-year, and 5-year OS rates are listed at Table 1. In univariate analysis, younger age (≤ 70 years), absence of intrahepatic tumor, lack of macrovascular invasion (MVI), and ALBI grade 1 were associated with an OS > 3 years. In multivariate analysis, after adjusting sex, viral hepatitis, MVI, extrahepatic spread, and initial alpha-fetoprotein > 400 ng/ml, the absence of intrahepatic tumor (Odds ratio [OR] = 5.36, p = 0.047) and ALBI grade 1 (vs grade 2, OR = 10.02, p = 0.037) remained independent predictors for OS > 3 years. Conclusions: In patients with advanced HCC, Atezo-Bev treatment led to a notable proportion achieving long-term survival, especially in patients with good response to the treatment. Absence of intrahepatic tumors and preserved liver function are predictive of prolonged survival. 3-year, 4-year and 5-year OS rate of patients who receive Atezo-Bev treatment, stratified by treatment response. Landmark survival OS rate (%) by treatment response Disease control Responder 3 years 35.6 52.2 4 years 30.3 52.2 5 years 30.3 47.7 Responder: patients who achieved a best response of complete response or partial response after treatment with Atezo-Bev. Disease control: includes responders and patients who achieved a best response of stable disease following Atezo-Bev treatment.