Dual split-signaling chimeric antigen receptor T-cells to safely treat Multiple Myeloma
Theuniformly and abundantly such as CD38 and CD138, are also expressed on a variety of healthy tissues. We exploited the fact that co-expression of CD38 and CD138 is limited to MM and plasma cells and applied the novel concept of split- dual CAR signaling. We have generated CD138/CD38 split- dual CAR T-cells, in which the two essential signals for T-cell activation, i.e. stimulation and co-stimulation were split into two CARs.
Primary human T-cells were retrovirally transduced with a bicistronic vector to express a CAR consisting of CD138 single chain variable fragment (scFv) linked to a CD3z cytoplasmic domain and a chimeric costimulatory receptor consisting of a CD38 scFv linked to CD28 and 4-1BB cytoplasmic domains. Split-signaling CAR T cells were tested against MM cell lines and primary human MM patients bone marrow, containing both MM cells and healthy cells, for their cytotoxic capacity, proliferating capacity and exhaustion profile.
The split-signaling dual CAR T-cells show excellent cytotoxicity against MM cell lines as well as primary MM cells. Healthy cells, present in the bone marrow, expressing CD38, but not CD138, remained largely untouched. Split-dual CAR T-cells also show increased cytokine production and proliferation against MM cells that express both targets simultaneously.
We show the feasibility and safety