We here propose to transiently express (i.e., through mRNA transfection for example) the STAT5A H298R/S710F mutant in human CD8 T cells specific for Ags expressed on solid malignancies to be used in ACT: Both their efficient infiltration into tumors and IFNγ production resistant to tumor-derived suppression should help to restore endogenous T cell responses and to reprogram TAM. Here, STAT5A is linked to neoplasm.