Spatiotemporal dynamics of the tumor microenvironment in hepatocellular carcinoma during combination immunotherapy
Hitoshi Iwasaki, Shinji Itoh, Katsuya Toshida, Junya Mita, Takuma Ishikawa, Norifumi Iseda, Kyohei Yugawa, Shohei Yoshiya, Takashi Motomura, Takeo Toshima, Shinichi Aishima, Yoshinao Oda, Tomoharu YoshizumiBackground:
Atezolizumab plus bevacizumab (ATZ/BEV) is a standard first-line therapy for advanced hepatocellular carcinoma (HCC); however, many patients do not achieve meaningful tumor regression. The temporal and spatial immune remodeling associated with ATZ/BEV remains poorly understood.
Methods:
We performed single-cell RNA sequencing of paired hepatectomy specimens obtained before and after ATZ/BEV from one patient and of tumor center and margin samples from another patient after ATZ/BEV. Cell composition, subclusters, and cell–cell communication were analyzed. In addition, candidate molecules identified by transcriptomic analysis were further assessed using serum-based assays and immunohistochemistry.
Results:
These single-cell analyses suggested that ATZ/BEV was associated with a shift toward an immune-active tumor microenvironment, with increased CD8
+
T cells together with reduced endothelial cells. CD8
+
T cells showed increased effector and exhaustion signatures, indicating coexistence of activation and dysfunction. CellChat analysis demonstrated selective activation of the TIGIT–PVR/NECTIN2 axis after treatment. Spatial analysis showed that the tumor margin was enriched for CD8
+
T cells and exhibited stronger effector and exhaustion activity than the tumor center. Immunoregulatory signaling was also more prominent at the margin. Serum TIGIT levels were significantly higher after ATZ/BEV than in upfront resection cases (
Conclusions:
Our exploratory findings suggest that ATZ/BEV may remodel the HCC microenvironment toward a state characterized by concurrent CD8 + T-cell activation and inhibitory signaling through the TIGIT–PVR/NECTIN2 axis, particularly at the tumor margin.