METTL1-mediated metabolic reprogramming regulates the expression of key immune checkpoints, including PD-L1 and CTLA-4, and is associated with an immunosuppressive TME, reduced infiltration of activated T cells, and adverse clinical outcomes (58) In breast cancer, METTL1 expression is significantly elevated in tumor tissues compared to normal tissues, demonstrating diagnostic value. The gene discussed is CTLA4; the disease is neoplasm.