HHLA2 and liver cancer: Within this cohort (n = 176), high HHLA2 protein expression was significantly associated with aggressive clinicopathological features, including larger tumors (p < 0.001), increased vascular invasion (p = 0.016), advanced Barcelona Clinic Liver Cancer (BCLC) stages (p < 0.001), and higher recurrence and metastasis rates (p < 0.001) (Supplemental Fig. 1G, Supplemental Table 1).