Whole-Transcriptome Profiling of Murine GL261 Glioma Reveals Signatures Consistent with Distinct Immune Reprogramming...

Both oncolytic virotherapy and immune checkpoint blockade are being actively explored as immunotherapy treatments for glioblastoma, one of the most lethal malignancies. Nevertheless, the antitumor molecular mechanisms of these therapies remain poorly understood, particularly whether they induce overlapping or distinct transcriptional programs. No comprehensive transcriptome-wide characterization and direct comparison of the responses induced by VV-GMCSF-Lact and anti-PD-1 therapy in glioma have been reported. To address this question, we performed whole-transcriptome profiling of GL261 tumors from immunocompetent C57BL/6 mice treated with VV-GMCSF-Lact, anti-PD-1 antibodies, or their combination. We analyzed therapy-associated changes in gene expression, signaling pathways, and tumor composition. Our findings indicate that anti-PD-1 and combination treatment led to distinctive activation of interferon-gamma response, JAK/STAT signaling, and TNF-alpha/NF-kB pathways. In contrast, VV-GMCSF-Lact preferentially activated T, B, and natural killer T cell-associated programs and reduced the relative abundance of malignant cells. Notably, combination therapy was associated with unique molecular patterns, including induction of monocyte and granulocyte chemotaxis-associated genes, downregulation of PP2A-regulated signaling, and suppression of Rap1-related pathways. This suggests that VV-GMCSF-Lact and anti-PD-1 therapy induce transcriptionally distinct, yet complementary, immune reprogramming and support further evaluation of their combination for glioma immunotherapy.