Base-edited CAR T cells for combinational therapy against T cell malignancies

Area of Science:

• Immunology
• Gene Editing
• Oncology

Background:

• Chimeric antigen receptor (CAR) T cell therapy is a promising treatment for T cell malignancies.
• CAR T cell therapy faces challenges like T cell fratricide due to shared antigens (CD3, CD7).
• Base editing offers a precise method to disrupt gene expression and eliminate target antigens.

Purpose of the Study:

• To engineer fratricide-resistant CAR T cells for treating T cell malignancies.
• To evaluate the efficacy and safety of base-edited CAR T cells targeting CD3 and CD7.
• To assess the potential of these modified T cells in preclinical models.

Main Methods:

• Utilized base editing to remove T cell receptor (TCR)/CD3 and CD7.
• Generated lentiviral CARs specific for CD3 or CD7.
• Co-cultured engineered T cells and assessed cytotoxicity against leukemia cell lines and primary T-ALL cells.
• Evaluated in vivo efficacy using a human:murine chimeric model.
• Performed molecular interrogation to confirm gene editing and assess off-target effects.

Main Results:

• Successfully generated fratricide-resistant T cells by removing CD3 and CD7.
• Base-edited cells showed elimination of chromosomal translocations compared to Cas9-treated cells.
• Co-cultured 3CAR/7CAR cells achieved >99% TCR-/CD3-/CD7- populations.
• Engineered CAR T cells demonstrated specific cytotoxicity against CD3/CD7 expressing leukemia and T-ALL cells.
• No significant off-target mutations or binding region alterations were detected.

Conclusions:

• Base editing enables the creation of fratricide-resistant CAR T cells for T cell malignancies.
• Engineered CAR T cells show potent anti-leukemia activity in vitro and in vivo.
• This approach offers a potential strategy for enhanced molecular remission prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT).