CD4 and neoplasm: Tumor-specific CD4+ T cells, particularly those targeting neoantigens, can also mediate tumor regression in mice and in patients, either directly by killing tumor cells or indirectly by secreting cytokines and chemokines that collectively reprogram myeloid cells in the TME and enhance CD8+ T cell function (Greenberg et al. 1981, 1985; Hunder et al. 2008; Tran et al. 2014; Veatch et al. 2018, 2019, 2022b).