Objective Response and Progression-Free Survival Contribute to Prolong Overall Survival in Atezolizumab plus Bevacizumab Treatment for Unresectable Hepatocellular Carcinoma.

INTRODUCTION: Atezolizumab plus bevacizumab (Atez/Bev) is a standard treatment for unresectable hepatocellular carcinoma (HCC) due to its good antitumor and survival prolongation effects. Post-progression survival (PPS) has been reported to be a great contributor in the treatment with tyrosine kinase inhibitors for unresectable HCC. This study aimed to clarify the significance of progression-free survival (PFS) or PPS of Atez/Bev treatment for HCC. METHODS: We analyzed the correlations of PFS and PPS with overall survival (OS) in studies of HCC patients treated with Atez/Bev and evaluated the contribution to OS in Atez/Bev treatment with patients at our institutions as clinical practice. RESULTS: Analysis of 18 studies involving 3,752 patients treated with Atez/Bev found that PPS had a stronger correlation with OS (R2 = 0.872, p < 0.001) than did PFS (R2 = 0.605, p = 0.001). Analysis of 80 patients with unresectable HCC treated with Atez/Bev found that presence of antitumor responses during Atez/Bev was the most significant contributor to OS, and post-progression treatment after Atez/Bev also significantly contribute to OS. CONCLUSION: The presence of antitumor response with tumor shrinkage during Atez/Bev treatment contributes to good OS through its durable response. Atez/Bev treatment could be considered as first-line treatment for unresectable HCC. However, there is a need for optimal biomarkers for good antitumor response.