CD4+ T-helper lymphocytes, which secrete type I cytokines, such as IFNγ and tumor necrosis factor α (TNFα), contribute to the induction of a cytotoxic antitumor response that cooperates with trastuzumab to upregulate MHC-I on HER2-positive BC cells, facilitating their recognition and lysis by CD8+ lymphocytes [31]. The gene discussed is ERBB2; the disease is breast cancer.