Identification of dominant leukemia-associated neoantigens and favoring specific priming and subsequent expansion of T cells reactive to these antigens might harbor therapeutic potential. Here, a new strategy combines a specific T-cell activation step using tumor lysate-pulsed bone marrow-derived dendritic cells with a nonspecific large-scale expansion method. The leukemia cell line C1498 transduced with a potentially immunodominant antigen (ovalbumin) was used to track expansion and functionality of antigen-specific cytotoxic T cell (CTL), both in vitro and in vivo. Three times more leukemia-specific CTL could be generated when compared with the respective controls. CTL generated after increasing the antigen-specific T-cell precursor frequency in vitro cured up to 80% of mice bearing leukemia with the respective antigen (P < 0.005, as compared with controls). Alternatively, the yield of CTL reactive to a immunodominant neoantigen increased by factor 2 to 6 when T-cell donors were immunized with dendritic cell presenting the respective antigen. However, increasing the leukemia-reactive precursor frequency to a clinically exploitable level will be the key for the design of successful T-cell therapy trials.