Impact of radiological response and pattern of progression in patients with hepatocellular carcinoma treated by atezolizumab- bevacizumab

Background and Aims: We aim to assess the role of radiological response to atezolizumab-bevacizumab in patients with HCC to predict overall survival. Approach and Results: We retrospectively included patients with HCC treated by atezolizumab-bevacizumab in 2 tertiary centers. A retrospective blinded analysis was performed by 2 radiologists to assess Response Evaluation Criteria in Solid Tumor (RECIST 1.1) and modified RECIST (mRECIST) criteria at 12 weeks. Imaging response and treatment decisions in the multidisciplinary tumor board at 12 weeks were registered. Among 125 patients, 9.6% and 20.8% had a response, 39.2% and 35.2% had stable disease, and 51.2% and 44% had progression, according to RECIST 1.1 and mRECIST, respectively, with a substantial interobserver agreement (k coefficient=0.79). Metastasis was independently associated with a higher risk of progression. Patients classified as responders did not reach median survival, which was 16.2 and 15.9 months for patients classified as stable and 9.1 and 9.0 months for patients classified as progressors, in RECIST 1.1 and mRECIST criteria, respectively. We observed a wide variability in the identification of progression in the multidisciplinary tumor board in clinical practice compared with the blind evaluation by radiologists mainly due to discrepancy in the evaluation of the increase in size of intrahepatic lesions. The appearance of new extrahepatic lesions or vascular invasion lesions was associated with a worse overall survival ( p =0.032). Conclusions: RECIST 1.1 and mRECIST criteria predict overall survival with more responders identified by mRECIST and the appearance of new extrahepatic lesion or vascular invasion was associated with a poor prognosis. A noticeable discrepancy was observed between patients classified as progressors at reviewing and the decision reached during the multidisciplinary tumor board.