TIM-3 (T cell immunoglobulin domain and mucin domain 3) is a negative checkpoint-regulator with functions similar to PD-L1; its expression was detected on type 1 CD4+ T-helper cells and cytotoxic CD8+ T-cells; later TIM3 expression was described on tumor cells (leukemia, glioblastoma) as a marker of worsening disease prognosis and resistance to chemotherapy [53,54,55]. The gene discussed is HAVCR2; the disease is leukemia.