Supplementary file 1_Immune escape in portal vein tumor thrombus: an intravascular tumor–immune niche framework for hepatocellular carcinoma.docx

Current stratification relies mainly on anatomical extent, liver function, and tumor burden and does not fully capture the biology of the intravascular lesion. In this Review, we propose PVTT as an anatomically distinct, lesion-centered intravascular tumor–immune niche for hypothesis generation rather than as an established autonomous immune compartment.

We distinguish PVTT-direct evidence from supportive venous-thrombus/metastatic evidence and HCC-extrapolated mechanisms. Current PVTT-direct evidence is strongest for clonal and spatial divergence and PVTT-specific stromal remodeling, including myofibroblast-like cancer-associated fibroblast accumulation, NID1-associated immune barriers, and FAP-positive fibroblast/GJA5-positive endothelial hubs. Venous-thrombus studies provide supportive evidence for macrophage-associated immune suppression, including C5aR-positive tumor-associated macrophages, whereas hypoxia–adenosine signaling, adaptive checkpoint activation, and lipid metabolic rewiring remain largely extrapolated candidate mechanisms requiring direct PVTT validation.