Based on the epigenetic regulation of tumor cGAS expression by ten-eleven translocation-2 (TET2) methylcytosine dioxygenase synergized with STAT5A signaling, we further stimulate TET2 activity using vitamin C (VC) to trigger tumor cGAS-cGAMP-endothelial STING pathway activation and induce tumor vascular normalization, thereby potentiating the therapeutic efficacy of immune checkpoint blockade in vivo. The gene discussed is STAT5A; the disease is neoplasm.