The deletion of UBE3A leads to gene changes, increased tumor mutation load, aggravated DNA damage, decreased mRNA expression and DNA methylation, thus activating immune-related pathways and consistent metabolism and the TGF-β pathway, which relieves the inhibition of CD4 and CD8 T cells and activates macrophages to activate the body’s response to immunotherapy. The gene discussed is CD8A; the disease is neoplasm.