Through paired single cell (sc) RNA-sequencing (seq) and scTCR-seq in newly diagnosed and relapsed/refractory (R/R) AML samples—followed by a battery of bioinformatics methods—profiling of the CD8+ T cells from R/R patients showed clonal hyperexpansion (especially in the cytotoxic effector group) with a terminal differentiation state and gene signature, in contrast to a more plastic T cell state in newly diagnosed patients, owing to chronic antigen stimulation [61]. The gene discussed is CD8A; the disease is acute myeloid leukemia.