Allogeneic CAR-NK Cell Therapy Targeting Both BCMA and GPRC5D for the Treatment of Multiple Myeloma

Anti-BCMA (B-cell maturation antigen) CAR-T cell therapies has shown great success in treating multiple myeloma (MM). However, disease relapse is still an issue attributing to variable BCMA expression, downregulation of BCMA， as well as tumor antigen heterogeneity in MM. Hence, targeting multiple antigens may improve the durability of disease control after cell therapy treatment. The orphan seven transmembrane G protein coupled receptor（GPRC5D）is another tumor antigen expressed on the cell surface of MM tumor cells. Early clinical results of GPRC5D targeted CAR-T cell therapy for MM showed a very manageable safety profile and promising efficacy in the patients of heavily pre-treated refractory/relapse multiple myeloma (RRMM). Although autologous CAR-T cell therapy has been approved to be an effective therapeutic approach to treat various hematologic tumors including RRMM, there are several limitations including high cost and complexity of production, and potentially severe toxicities. Therefore, allogeneic NK cell-based therapies have been receiving more and more attention in cancer immunotherapy due to its off-shelf property, low toxicity, low cost, and no graft-vs-host-diseases (GvHD). Here, we are developing dual targeting CAR-NK cell product targeting both BCMA and GPRC5D with novel CAR design. We have screened 37 dual targeting CARs using anti-BCMA VHHs and anti-GPRC5D VHHs，and final lead dual targeting CAR-NK cells showed potent efficacy against MM cell lines including both high and low expression levels of BCMA and GPRC5D. Moreover, in comparison with single targeting BCMA CAR-NK cells, BCMA/GPRC5D dual-targeted CAR-NK cells effectively lysed BCMA negative target cells. In vivo efficacy of BCMA/GPRC5D dual-targeted CAR-NK cells was also evaluated in NPG mice engrafted with a human MM cell line (Luc+), and results consistently elicited that BCMA/GPRC5D dual-targeted CAR-NK cells improved animal survival and reduced tumor relapse compared to single targeting CAR-NK cells. These results indicate that BCMA/GPRC5D dual-targeted CAR-NK cell therapy has great potential to be used in MM patients as an off-the-shelf therapeutic product to further improve response duration compared to BCMA or GPRC5D single targeted cell therapy.