Natural killer (NK) cells are primary immune cells that target cancer cells and can be used as a therapeutic agent against pancreatic cancer. Despite the usefulness of NK cells, NK-cell therapy is limited by tumor cell inhibition of NK-cell homing to tumor sites, thereby preventing a sustained antitumor immune response. One approach to successful cancer immunotherapy is to increase trafficking of NK cells to tumor tissues. Here, we developed an antibody-based NK-cell-homing protein, named NK-cell-recruiting protein-conjugated antibody (NRP-body). The effect of NRP-body on infiltration of NK cells into primary and metastatic pancreatic cancer was evaluated in vitro and in murine pancreatic ductal adenocarcinoma models. The NRP-body increased NK-cell infiltration of tumors along a CXCL16 gradient (CXCL16 is cleaved from the NRP-body by furin expressed on the surface of pancreatic cancer cells). CXCL16 induced NK-cell infiltration by activating RhoA via the ERK signaling cascade. Administration of the NRP-body to pancreatic cancer model mice increased tumor tissue infiltration of transferred NK cells and reduced the tumor burden compared with that in controls. Overall survival of NRP-body-treated mice (even the metastasis models) was higher than that of mice receiving NK cells alone. In conclusion, increasing NK-cell infiltration into tumor tissues improved response to this cancer immunotherapy. The combination of an NRP-body with NK-cell therapy might be useful for treating pancreatic cancer.
©2018 American Association for Cancer Research.