shRNA-based PD-1 suppression preserves memory phenotype and function of CD19-targeted CAR-T cell

Area of Science:

• Immunotherapy
• Oncology
• Cellular Biology

Background:

• Chimeric antigen receptor T cell (CAR-T) therapy targeting CD19 shows promise for B-cell acute lymphoblastic leukemia (B-ALL).
• Long-term efficacy of CD19-targeted CAR-T therapy is limited by T-cell exhaustion.
• Programmed cell death protein 1 (PD-1) in the tumor microenvironment suppresses CAR-T cell function.

Purpose of the Study:

• To investigate the effect of shRNA-mediated PD-1 knockdown on CAR-T cells.
• To alleviate CAR-T cell exhaustion and preserve memory phenotype.
• To enhance the long-term efficacy of CD19-targeted CAR-T cells.

Main Methods:

• Screened multiple shRNA candidates for PD-1 knockdown in CD19-CAR-T cells.
• Assessed cytotoxicity, cytokine secretion, and proliferation of PD-1 knockdown CAR-T cells.
• Evaluated memory phenotype, exhaustion markers, and cytolytic function after antigen stimulation in vitro and in vivo using NPG mice.

Main Results:

• PD-1 knockdown significantly enhanced CAR-T cell cytotoxicity and persistence against CD19+ tumor cells.
• PD-1 knockdown CAR-T cells sustained cytotoxic activity and retained a memory-like phenotype after repeated antigen stimulation.
• In vivo studies showed prolonged survival without cytokine release syndrome (CRS), indicating improved efficacy and safety.

Conclusions:

• PD-1 knockdown mitigates tumor-induced T-cell exhaustion in CAR-T cells.
• This strategy enhances the durability and potency of CAR-T cell therapy for cancer treatment.