When co‐cultured with organoids that overexpress IL‐4I1, tumour‐reactive CD8+ T cells showed up‐regulated exhaustion‐associated surface biomarkers (PD‐1 and T cell immunoglobulin and mucin domain‐containing‐3 (TIM3)) and impaired cytolytic activity against cancer cells.112. The gene discussed is CD8A; the disease is cancer.