EOMES (eomesodermin) is a transcription factor that plays critical roles in T cell differentiation and function, particularly in CD8+ T cells during immune responses. EOMES regulates the expression of cytotoxic genes and exhaustion markers in CD8+ T cells, with EOMES+ effector memory T cells being significantly more abundant in melanoma patients responding to anti-PD-1/anti-CTLA-4 combination immunotherapy 1. The transcription factor is associated with IFNγ regulation in GZMK+ effector memory T cells within colorectal tumors 2. EOMES expression can be epigenetically upregulated by metabolites like itaconate, which promotes CD8+ T cell exhaustion through succinate-dependent H3K4me3 modifications of the EOMES promoter, leading to increased PD-1 and TIM-3 expression 3. In autoimmune vasculitis, EOMES+ cytotoxic CD4+ T cells represent one of two effector populations derived from stem-like TCF1+ CD4+ T cells that maintain chr3 inflammation 4. Additionally, EOMES has been identified as part of transcription factor networks in triple-negative breast cancer immune signatures 5. Beyond immune function, EOMES contributes to cortical development by regulating basal progenitor cells expressing both PAX6 and EOMES, which are important for cortical expansion 6.