Curative therapy after atezolizumab and bevacizumab treatment for unresectable hepatocellular carcinoma: A multinational retrospective study.

TPS607 Background: The combination of atezolizumab and bevacizumab (Atezo-Bev) has transformed the treatment landscape for unresectable hepatocellular carcinoma (HCC). With a response rate of approximately 30%, some patients become eligible for curative locoregional therapies (LRT) after successful systemic treatment. However, it remains unclear whether patients who achieve a partial response (PR) and are converted to a disease-free state with curative LRT have a similar prognosis to patients who achieve a complete response (CR) from Atezo-Bev alone. Additionally, it is unknown whether applying curative LRT improves survival outcomes for patients who achieve a PR. This study aims to address these critical questions. Methods: This multinational, retrospective study will enroll patients with clinically or histologically diagnosed HCC who received first-line Atezo-Bev and achieved a CR or PR according to RECIST v1.1. Patients must have started Atezo-Bev before September 30, 2024. Patients receiving concurrent anti-CTLA4 antibodies will be excluded. Curative LRT is defined as curative surgery, ablation, or definitive radiotherapy performed in patients who achieved a PR with Atezo-Bev treatment during their PR status. The primary endpoint is the recurrence-free survival (RFS) of patients who received curative LRT, compared to that of patients who obtained a CR solely from Atezo-Bev treatment. Secondary endpoints include the time to discontinuation of Atezo-Bev treatment after curative LRT, and the time from initiation of Atezo-Bev treatment to curative LRT; also, the overall survival and progression-free survival of patients who received curative LRT with be compared with those of patients who obtained CR solely from Atezo-Bev treatment and those of patients who obtained a PR after Atezo-Bev treatment but did not receive LRT. Disease-free status after curative surgery must be confirmed by imaging. Time from the best objective response to curative LRT will also be recorded. Data will be collected from up to 30 Asian sites, with an anticipated sample size of approximately 400 patients who received curative LRT and 1,200 patients who achieved a CR or PR without receiving curative LRT. Survival outcomes will be analyzed using Kaplan-Meier methods and compared with the log-rank test. They will be adjusted for baseline characteristics such as age, gender, HCC etiology, tumor extent, liver function reserve, alpha-fetoprotein level, and neutrophil/lymphocyte ratio using Cox proportional hazards models. The study is partially supported by Roche. Clinical trial information: NCT07091942 .