Outcomes of conversion surgery after immune checkpoint inhibitor-based combination therapy in initially unresectable hepatocellular carcinoma: A retrospective cohort study.

2607 Background: Hepatocellular carcinoma (HCC) has a high incidence rate and is often asymptomatic in its early stages. Combination therapies using immune checkpoint inhibitors (ICIs) have demonstrated survival benefits and high objective response rates, offering hope for conversion surgery in patients with initially unresectable HCC. We aimed to investigate the oncological outcomes of conversion surgery compared to those with continuing systemic treatment alone in patients who responded well to ICIs-based therapy, as well as the surgical outcomes associated with conversion surgery. Methods: We consecutively enrolled patients diagnosed with HCC between January 1, 2019 and April 1, 2024. These patients received treatment with ICIs combined with either anti-VEGF antibodies or tyrosine kinase inhibitors. Tumor response and resectability were assessed every 2 months. Patients who responded positively and met the criteria for conversion surgery were included. Results: Among 613 patients with initially unresectable HCC, 136 achieved conversion and met the surgical resection criteria during combination therapy. The median follow-up time was 26.9 and 42.5 months for the surgery and non-surgery groups, respectively. The median PFS was 29.1 months in the surgery group versus 11.2 months in the non-surgery group (P < 0.0001, hazard ratio [HR] = 0.40 [0.25–0.63]). The median OS was 50.8 months in the surgery group, compared to 25.8 months in the non-surgery group (P < 0.0001, HR = 0.27 [0.15–0.47]). The median RFS was 18.7 months in the surgery group. Multivariate Cox regression analysis indicated that conversion surgery was independently associated with improved OS and PFS (P < 0.001), and continuing the original treatment post-surgery significantly influenced OS and RFS. Conclusions: Conversion surgery after meeting the surgical criteria during immunotherapy provides significant prognostic benefits for patients with initially unresectable HCC, demonstrating high safety and R0 resection rates. For those specifically selected based on their response to immunotherapy and undergoing conversion surgery, promptly resuming the original treatment after surgery is necessary. Our results emphasize the importance of continuing immunotherapy post-conversion surgery to prevent recurrence in patients who respond to immunotherapy.