TCR KO supports allogeneic CAR T cells, but also results in CD3 antigen loss from the cell surface. Lu et al. engineered a CD3ε fusion receptor (CD3FR) that could be expressed on TCR- cells and engaged with T cell engagers (TCEs) for T cell signaling and activation. Via CAR and TCEs, iPSC-derived TCR- CD3FR+ CAR T cells could target one or multiple tumor antigens to improve cytotoxicity over control CAR T cells in vitro (especially at low E:T and with repeated stimulation) and in vivo, including against heterogeneous tumors. CD3FR+ CAR T cells secreting TCEs showed enhanced cytotoxicity and engaged bystander T cells. The CD3FR-TCE strategy also improved CAR iNK cell efficacy.
Contributed by Alex Najibi
ABSTRACT: Chimeric antigen receptor (CAR) T cell therapies have shown clinical success in treating hematologic malignancies. However, heterogeneous target antigen expression can impair the durability of response. Combining CAR and T cell engagers (TCEs) targeting additional tumor antigens can address tumor heterogeneity and antigen escape. In allogeneic settings, eliminating the T cell receptor (TCR) of the adoptive T cell therapy prevents graft-versus-host disease. However, the absence of TCR leads to loss of surface CD3 expression, preventing cooperative activity with CD3-directed TCEs. We utilized induced pluripotent stem cells (iPSCs) to support the required multiplexed editing, establish a renewable starting material for off-the-shelf manufacture, and create the desired TCR-less CAR+ CD3+ T cells. Here, we illustrate surface expression of a CD3ε fusion receptor (CD3FR) in iPSC-derived CAR T (CAR iT) cells, enabling TCE-mediated targeting of diverse antigens. In vitro and in vivo, CD3FR+ CAR iT cells demonstrated potent cytotoxic response and cooperative activity against mixed tumor lines and multiple antigens. CD3FR+ iT cells were further engineered to secrete TCEs, eliminating the need for extra supplementation with TCEs. Collectively, the data highlight the ability to integrate TCEs with allogeneic CAR iT cells for multi-antigen targeting, overcoming tumor relapse, and supporting off-the-shelf therapy for patient access.


