Engineered triple inhibitory receptor resistance improves anti-tumor CAR-T cell performance via CD56

Area of Science:

• Immunology
• Oncology
• Cell Biology

Background:

• Inhibitory receptors programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin-domain containing-3 (Tim-3), and Lymphocyte-activation gene 3 (Lag-3) are highly expressed on tumor-infiltrating lymphocytes, impairing their anti-tumor functions.
• Chimeric antigen receptor T (CAR-T)-cell exhaustion is a significant hurdle in effective cancer immunotherapy.

Purpose of the Study:

• To investigate the simultaneous downregulation of PD-1, Tim-3, and Lag-3 on CAR-T cells to enhance anti-tumor activity.
• To explore the epigenetic modifications, tumor infiltration, and effector functions of these modified CAR-T cells.

Main Methods:

• Simultaneous genetic blockade of PD-1, Tim-3, and Lag-3 on CAR-T cells, creating PTL-CAR-T cells.
• Analysis of epigenetic modifications in PTL-CAR-T cells.
• Assessment of tumor infiltration, CD56 (NCAM) expression, interferon-gamma secretion, and CAR-T cell survival in vivo.
• Evaluation of the homophilic interaction of CD56 molecules.

Main Results:

• PTL-CAR-T cells exhibited epigenetic modifications and improved control over tumor growth.
• Unexpectedly, PTL-CAR-T cells showed increased tumor infiltration and clustered at the interface of living and necrotic tumor tissue.
• PTL-CAR-T cells upregulated CD56 (NCAM), which was crucial for their effector functions.
• Homophilic CD56 interactions correlated with enhanced CAR-T cell infiltration, increased interferon-gamma secretion, and prolonged CAR-T cell survival.

Conclusions:

• Genetic blockade of PD-1, Tim-3, and Lag-3, coupled with high CD56 expression, significantly enhances CAR-T cell survival and anti-tumor responses.
• This dual strategy offers a promising approach to overcome CAR-T cell exhaustion and improve cancer immunotherapy efficacy.