Hyperprogressive disease in patients with unresectable hepatocellular carcinoma receiving atezolizumab plus bevacizumab therapy

Background Atezolizumab plus bevacizumab was approved for hepatocellular carcinoma (HCC) patients in 2020, but treatment outcomes of atezolizumab plus bevacizumab in real‐world settings remain unclear. Hyperprogressive disease (HPD), an acceleration of tumor growth occurring in some types of malignancies treated with immune checkpoint inhibitors, was assessed in HCC patients receiving atezolizumab plus bevacizumab. Methods Tumor growth kinetics (TGK) and tumor growth rate (TGR) were calculated at pre‐ and post‐treatment in 88 Japanese patients with HCC receiving atezolizumab plus bevacizumab. Hyperprogressive disease was defined as progressive disease (PD) with ≥ two‐fold increase in TGK and TGR. The association of baseline characteristics with HPD was analyzed. Results The best objective responses were partial response, stable disease, and PD in 12 (13.6%), 51 (58.0%), and 25 (28.4%) patients, respectively. The median progression‐free survival was 5.0 months. Eleven (12.5%) and 9 (10.2%) patients had a TGK ratio and a TGR ratio of ≥2, respectively. Hyperprogressive disease was observed in nine patients (10.2%) and they showed significantly shorter overall survival than patients without HPD (median, 4.3 months vs. not reached; p