Notably, genes associated with immune checkpoints, such as PDCD1 (PD-1), CTLA4 (CTLA-4), and CD274 (PD-L1), were significantly downregulated in SNMM-enriched cluster B (p = 0.0239, p = 0.0021, and p = 0.0048, respectively) compared to cluster A. This reduced expression suggests a tumor microenvironment that is less responsive to immune checkpoint inhibitors in cluster B, consistent with the poor responsiveness of SNMM to immunotherapy [41]. This evidence concerns the gene CTLA4 and neoplasm.