Comparison of seven CD19 CAR designs in engineering NK cells for enhancing anti-tumour activity

Abstract

Chimeric antigen receptor-natural killer (CAR-NK) cell therapy is emerging as a promisingcancer treatment, with notable safety and source diversity benefits over CAR-Tcells. This study focused on optimizing CAR constructs for NK cells to maximize theirtherapeutic potential. We designed seven CD19 CAR constructs and expressed themin NK cells using a retroviral system, assessing their tumour-killing efficacy and persistence.Results showed all constructs enhanced tumour-killing and prolonged survivalin tumour-bearing mice. In particular, CAR1 (CD8 TMD-CD3ζ SD)-NK cells showedsuperior efficacy in treating tumour-bearing animals and exhibited enhanced persistencewhen combined with OX40 co-stimulatory domain. Of note, CAR1-NK cellswere most effective at lower effector-to-target ratios, while CAR4 (CD8 TMD-OX40CD- FcϵRIγ SD) compromised NK cell expansion ability. Superior survival rates werenoted in mice treated with CAR1-, CAR2 (CD8 TMD- FcϵRIγ SD)-, CAR3 (CD8 TMDOX40CD- CD3ζ SD)- and CAR4-NK cells over those treated with CAR5 (CD28TMD- FcϵRIγ SD)-, CAR6 (CD8 TMD-4-1BB CD-CD3ζ 1-ITAM SD)- and CAR7 (CD8TMD-OX40 CD-CD3ζ 1-ITAM SD)-NK cells, with CAR5-NK cells showing the weakestanti-tumour activity. Increased expression of exhaustion markers, especially inCAR7-NK cells, suggests that combining CAR-NK cells with immune checkpointinhibitors might improve anti-tumour outcomes. These findings provide crucialinsights for developing CAR-NK cell products for clinical applications.

RIGHTS & PERMISSIONS

2024 The Author(s). Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.