Adjuvant Cytokine-Induced Killer Cell Immunotherapy in Hepatocellular Carcinoma: Real-World Data and 9-Year Extended Follow-Up of a Randomized Controlled Trial

Most adjuvant therapies for hepatocellular carcinoma (HCC) have failed except for autologous cytokine-induced killer (CIK) therapy, which prolonged recurrence-free survival (RFS) in a previously reported randomized controlled trial (RCT) and real-world data (RWD). This study aimed to assess the long-term outcomes of adjuvant CIK therapy using both an extended follow-up of the original RCT and a retrospective cohort study. An extended follow-up analysis of the RCT included 226 patients (114 in the CIK group and 112 in the control group). The follow-up duration was extended from 2 to 9 years after the enrollment of the last patient. In parallel, a retrospective RWD study was performed involving 577 patients from two tertiary centers in Korea, including 251 who received adjuvant CIK therapy and 326 controls. Propensity score matching (PSM) was applied to adjust for baseline imbalances. The primary endpoint was RFS in both studies. In the RWD study (median follow-up = 57.2 months), the CIK group demonstrated significantly prolonged RFS than controls both before PSM (median = 101.2 versus 64.7 months; HR = 0.69, 95