TCR extracellular domain genetically linked to CD28, 2B4/41BB and DAP10/CD3 zeta -engineered NK cells mediates antitumor effects

NK cells, especially FDA-approved NK-92 cells, could be used for TCR engineering owing to their specialized cytotoxicity against tumors, safety profile and potential use as an off-the-shelf cellular therapy. The TCR complex requires assembly of TCR- alpha/ beta chains with CD3 molecules (CD3 delta, CD3 gamma, CD3 epsilon, CD3 zeta) to be correctly expressed at the cell membrane, and yet NK cells lack expression of these CD3 subunits besides CD3 zeta. Since transmembrane regions of TCR alpha and beta chains are involved in TCR complex assembly, transmembrane regions of TCR replaced by CD28 transmembrane domain could result in the expression of TCR independent of its companion CD3 subunits. However, since the absence of CD3 signaling components can influence the transmission of TCR signals to NK cells, it is necessary to add the signaling molecules of NK cells followed by CD28 transmembrane domain. Both CD3 zeta and DAP10 play an important role in the activation and cytotoxicity of NK cells; moreover, 2B4 and 4-1BB are the main costimulatory molecules in NK cells. Therefore, we designed a chimeric TCR that consisted of the extracellular domains of the TCR alpha and beta chains specific for NYESO-1 fused to the CD28 transmembrane domain followed by the 41BB and CD3 zeta signaling domains as well as the 2B4 and DAP10 signaling domain, respectively. The chimeric TCR genetically engineered NK-92 cells exhibit antigen-specific recognition and lysis of tumor cells both in vitro and in vivo. In addition, TCR-28-2B10/BB zeta can be feasibly expressed in primary NK cells and exhibit antigen-reactive recognition and effect function. The overall encouraging data highlight the value of NK-92 cells and primary NK cells engineered to express therapeutic chimeric TCR for adoptive immunotherapies.