Figure 1. Predictive immune cell markers for identifying patients who can stop imatinib without relapse. (A) Hypothetical kinetics regarding the activation level of natural killer (NK) cells, total CD8⁺ T cells, and chronic myeloid leukemia (CML) antigen-specific cytotoxic T lymphocyte (CTLs). Total CD8⁺ T cells appear to be more susceptible to imatinib than NK cells. It is predicted that patients who have sustained and higher levels of activated NK cells and/or CML antigen–specific CTLs can safely stop imatinib without relapse. (B) Combined prediction using multiple markers, such as the presence of IFNγ⁺ NK cells and CML antigen–specific CTLs, could be a more reliable strategy.