An NKp30-based chimeric antigen receptor promotes T-cell effector functions and anti-tumor efficacy in vivo

摘要

NKp30 is a natural cytotoxicity receptor (NCR) that is expressed on natural killer (NK) cells and recognizes B7-H6, which is expressed on several types of tumors but few normal cells. To target effector T cells against B7-H6-positive tumors, we have developed several chimeric antigen receptors (CAR) based on NKp30, which contain the CD28 and/or CD3ζ signaling domains with the transmembrane domains from CD3ζ, CD28 or CD8α, respectively. The data show that chimeric NKp30-expressing T cells responded to B7-H6-positive tumor cells. The NKp30 CAR expressing T cells produced IFN-γ and killed B7-H6 ligand-expressing tumor cells, and this response was dependent upon ligand expression on target cells but not on MHC expression. PBMC-derived dendritic cells (DCs) also express NKp30 ligands, including immature DCs (iDCs), and they can stimulate NKp30 CAR-bearing T cells to produce IFN-γ, but to a lesser extent. The addition of a CD28 signaling domain significantly enhanced the activity of the NKp30 CAR in a PI3-kinase-dependent manner. Adoptive transfer of T cells expressing a chimeric NKp30 receptor containing a CD28 signaling domain inhibited the growth of a B7-H6-expressing murine lymphoma (RMA/B7-H6) in vivo. Moreover, mice that remained tumor-free were resistant to a subsequent challenge with the wildtype RMA tumor cells, suggesting the generation of immunity against other tumor antigens. Overall, this study demonstrates the specificity and therapeutic potential of adoptive immunotherapy with NKp30 CAR-expressing T cells against B7-H6⁺ tumor cells in vivo.