e16123 Background: Transcatheter arterial chemoembolization (TACE) has been combined with immune checkpoint inhibitor (ICI)-based systematic therapies for unresectable HCC (uHCC) with promising efficacy. However, whether the addition of TACE to the combination of ICI and tyrosine kinase inhibitor (TKI) (ICI+TKI+TACE) is superior to ICI+TKI combination therapy is still not clear. Thus, this study compares the efficacy of ICI+TKI+TACE triple therapy and ICI+TKI doublet therapy in patients with uHCC. Methods: uHCC patients treated with either ICI+TKI+TACE triple therapy or ICI+TKI doublet therapy were retrospectively recruited between January 2016 and December 2021 at Eastern Hepatobiliary Surgery Hospital. The patients from ICI+TKI+TACE group and ICI+TKI group were further subjected to propensity score matching based on the baseline characteristics. The primary outcome was progression-free survival (PFS) in matched patients. The secondary outcomes were overall survival (OS) and objective response rate (ORR). Post-progression survival (PPS) as well as treatment-related adverse events (TRAEs) were also assessed. Results: A total of 120 patients were matched. The median PFS was 8.4 months in ICI+TKI+TACE triple therapy group versus 6.6 months in ICI+TKI doublet therapy group (HR 0.72, 95%CI 0.48-1.08; p=0.115). Similar results were obtained in term of OS (26.9 versus 24.2 months, HR 0.88, 95% CI 0.51-1.52; p=0.670). The ORR in the triple therapy group was comparable with that in the doublet therapy group (16.6% versus 21.6%, p=0.487). Further subgroup analysis for PFS illustrated that patients without previous locoregional treatment (preLRT) (10.5 versus 3.7 months, HR 0.35 [0.16-0.76]; p=0.009), without previous treatment (10.5 versus 3.5 months, HR 0.34 [0.14-0.81]; p=0.015) or treated with lenvatinib (14.8 versus 6.9 months, HR 0.52 [0.31-0.87]; p=0.013) can significantly benefit from triple therapy compared with doublet therapy. A remarkable interaction between treatment and preLRT ( p=0.049) or TKIs-combined ( p=0.005) was also detected in term of PFS. Kaplan-Meier analysis of PPS revealed that patients with post progression treatment displayed significant improved survival in both ICI+TKI+TACE and ICI+TKI groups. The incidence of TRAEs was comparable between two groups. Conclusions: In selected uHCC patients (without preLRT or treated with lenvatinib as combination), the addition of TACE to ICI+TKI combination therapy can remarkably improve PFS.