Abstract
BackgroundThe therapeutic application of T cells endowing with chimeric antigen receptors (CARs) is faced with “on-target, off-tumor” toxicity against solid tumors, particularly in the treatment of the pancreatic cancer. To our best knowledge, the pancreatic cancer cell line AsPC-1 often highly expressed some distinct tumor-associated antigens, such as carcino-embryonic antigen (CEA) and mesothelin (MSLN). Therefore, in this research, we have characterized dual-receptor CAR-modified T cells (dCAR-T) that exert effective and safe cytotoxicity against AsPC-1 cells.MethodsBased on the dual signaling pathway of wild T cells, we designed a novel dCAR diagram specific for CEA and MSLN, which achieved comparable activity relative to that of conventional CAR-T cells (CEA-CAR T or MSLN-CAR T). In this dCAR, a tandem construct containing two physically separate structures, CEA-CD3ζ and MSLN-4/1BB signaling domains were effectively controlled with tumor antigens CEA and MSLN, respectively. Finally, the activity of dCAR-T cells has been verified via in vitro and in vivo experiments.ResultsIn the presence of cognate tumor cells (AsPC-1) expressing both CEA and MSLN, dCAR-T cells exerted high anti-tumor activity relative to that of other single-receptor CAR-T cells bearing only one signaling pathway (e.g., Cζ-CAR and MBB-CAR). In a xenograft model, dCAR-T cells significantly inhibited the growth of AsPC-1 cells yet no effect on the growth of non-cognate tumor cells. Furthermore, the released cytokines and T cell persistence in mice were comparable with that of conventional CAR-T cells, obtaining specific and controllable cytotoxicity.ConclusionsA novel type of CAR-T cells, termed dCAR-T, was designed with specific activities, that is, significant cytotoxicity for two antigen-positive tumor cells yet no cytotoxicity for single antigen-positive tumor cells. Dual-targeted CAR-T cells can be precisely localized at the tumor site and can exert high cytotoxicity against tumor cells, alleviating “on-target, off-tumor” toxicity and enabling accurate application of CAR-T cell therapy.
Highlights
The therapeutic application of T cells endowing with chimeric antigen receptors (CARs) is faced with “on-target, off-tumor” toxicity against solid tumors, in the treatment of the pancreatic cancer
In this CAR, a CD3ζ-mediated activation signal was dependent upon recognition of the tumor antigen carcino-embryonic antigen (CEA) and a 4/ 1BB co-stimulation signal domain was subjected to the second receptor specific for tumor antigen MSLN (Fig. 1a)
We provided two negative controls, single-receptor CARs including CEA-CD3ζ CAR (Cζ-CAR) and MSLN-4/1BB CAR (MBB-CAR), and two positive controls, the second-generation CAR specific for CEA (CEA-CAR) and the second-generation CAR specific for MSLN (MSLN-CAR) (Fig. 1b, Additional file 1: Figure S1)
Summary
The therapeutic application of T cells endowing with chimeric antigen receptors (CARs) is faced with “on-target, off-tumor” toxicity against solid tumors, in the treatment of the pancreatic cancer. This type of cancer immunotherapy is capable of immediately providing ongoing tumor control and possible protection against recurrence in some clinical trials, a promising approach to adoptive T cell therapy for cancer treatment [5,6,7,8,9] This type of immunotherapy holds a tremendous response for tumor elimination, especially in some hematological malignancies [10,11,12], it has recently been faced with a serious limitation caused by treatment-induced adverse effects in some clinical trials, such as “on-target, off-tumor” toxicity [13, 14]. Some new approaches to treat solid tumors with sustained tumor elimination and reduced side effects are needed
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