ERBB2 and neoplasm: The tumor microenvironment varies greatly among subtypes, with high T-cell infiltration but strong immunosuppression in TNBC; HER2+ type has STING pathway inhibition leading to trastuzumab resistance, and the Luminal type has AKT1 overactivation weakening immune response; systemic immune activation may also trigger cytokine storms or autoimmune reactions (10–12).