Bispecific killer cell engager (BiKE) that ligate CD16 on NK cells and a tumor antigen on tumor cells has been developed to activate NK cells and induce target cell lysis, to further improve activation, expansion, and survival of NK cells, a modified IL-15 crosslinker is infused into BiKE to create trispecific killer engager (TriKE) which has shown superior anti-tumor activity compared with BiKE [174, 175] (Fig. 3). The gene discussed is IL15; the disease is neoplasm.