Prediction of Therapeutic Response Using Contrast-Enhanced Ultrasound in Japanese Patients Treated with Atezolizumab and Bevacizumab for Unresectable Hepatocellular Carcinoma

Introduction: Atezolizumab and bevacizumab (AB) therapy was the first-line treatment for unresectable hepatocellular carcinoma (u-HCC). However, the predictive marker of therapeutic response that can be easily used in clinical practice is still unknown. We prospectively investigated the utility of time-intensity curve (TIC) analysis using contrast-enhanced ultrasound (CEUS) as a predictive indicator of therapeutic response after the start of AB therapy. Methods: Thirty-five patients who received AB therapy for u-HCC were included in this study. TIC analysis was performed in 28 patients who were able to undergo CEUS before and 3–7 days after administration. We analyzed prognostic factors related to the initial therapeutic response and long progression-free survival (PFS). Results: The initial therapeutic response using dynamic computed tomography or Gd-EOB magnetic resonance imaging at 8–12 weeks after administration was partial response/stable disease/progressive disease (PD) in 14/12/9 cases (40/34/26%). Cases with PD (n = 9) had more cases without decreased blood flow in TIC analysis compared with cases with non-PD (100 vs. 18%, p = 0.001). Cases without decreased blood flow in TIC analysis (n = 10) had more cases with PD compared with cases with decreased blood flow (60 vs. 0%, p = 0.001). PFS in patients without decreased blood flow early after the administration was shorter than that in those with decreased blood flow (9.1 vs. 28 weeks, p = 0.0051). Conclusion: Early evaluation by TIC analysis using CEUS may be useful in predicting the therapeutic response in patients treated with AB therapy for u-HCC.