The benefit of conversion therapy for patients with unresectable hepatocellular carcinoma receiving atezolizumab plus bevacizumab using newly established oncological resectability criteria in Japan

BACKGROUND: This study aimed to investigate the changes in oncological resection status in patients with unresectable hepatocellular carcinoma (u-HCC) receiving atezolizumab plus bevacizumab (Atez/Bev) and the impact of conversion therapy following Atez/Bev treatment. METHODS: This cohort included 631 patients with u-HCC treated with Atez/Bev. Tumors were assessed using oncological resectability criteria and categorized as borderline resectable 1 (BR1, n=166) or borderline resectable 2 (BR2, n=465). RESULTS: Overall, 129 (20.4%) patients were downstaged based on oncological resectability criteria. Among them, 28 (16.8%) patients were downstaged from BR1 to resectable (R), and 49 (10.5%) and 52 (11.1%) patients were downstaged from BR2 to R and from BR2 to BR1, respectively. The percentage of patients who underwent conversion therapy was 5.4%. For patients categorized as BR1 and BR2 before Atez/Bev treatment, the rates of conversion therapy were 8.4% (14/166) and 4.3% (20/465), respectively. Overall survival (OS) was significantly higher in the conversion therapy group than in the partial response group (not reached vs. 36.4 months, p=0.001), with no significant differences compared to the complete response group. The median recurrence-free survival was 15.7 months after conversion therapy. Although there were differences in patient background data at the time of conversion therapy, surgery had a significantly higher RFS than radiofrequency ablation (not reached vs. 10.0 months, p=0.008). CONCLUSIONS: When feasible, conversion therapy should be considered to improve the prognosis of u-HCC patients treated with Atez/Bev. Moreover, oncological resectability criteria may provide a useful tool for investigators regarding conversion therapy.