[HTML][HTML] Long terminal repeat CRISPR-CAR-coupled “universal” T cells mediate potent anti-leukemic effects

C Georgiadis, R Preece, L Nickolay, A Etuk, A Petrova… - Molecular Therapy, 2018 - cell.com
C Georgiadis, R Preece, L Nickolay, A Etuk, A Petrova, D Ladon, A Danyi
Molecular Therapy, 2018cell.com
Gene editing can be used to overcome allo-recognition, which otherwise limits allogeneic T
cell therapies. Initial proof-of-concept applications have included generation of such"
universal" T cells expressing chimeric antigen receptors (CARs) against CD19 target
antigens combined with transient expression of DNA-targeting nucleases to disrupt the T cell
receptor alpha constant chain (TRAC). Although relatively efficient, transgene expression
and editing effects were unlinked, yields variable, and resulting T cell populations …
Gene editing can be used to overcome allo-recognition, which otherwise limits allogeneic T cell therapies. Initial proof-of-concept applications have included generation of such "universal" T cells expressing chimeric antigen receptors (CARs) against CD19 target antigens combined with transient expression of DNA-targeting nucleases to disrupt the T cell receptor alpha constant chain (TRAC). Although relatively efficient, transgene expression and editing effects were unlinked, yields variable, and resulting T cell populations heterogeneous, complicating dosing strategies. We describe a self-inactivating lentiviral "terminal" vector platform coupling CAR expression with CRISPR/Cas9 effects through incorporation of an sgRNA element into the ΔU3 3′ long terminal repeat (LTR). Following reverse transcription and duplication of the hybrid ΔU3-sgRNA, delivery of Cas9 mRNA resulted in targeted TRAC locus cleavage and allowed the enrichment of highly homogeneous (>96%) CAR+ (>99%) TCR populations by automated magnetic separation. Molecular analyses, including NGS, WGS, and Digenome-seq, verified on-target specificity with no evidence of predicted off-target events. Robust anti-leukemic effects were demonstrated in humanized immunodeficient mice and were sustained longer than by conventional CAR+TCR+ T cells. Terminal-TRAC (TT) CAR T cells offer the possibility of a pre-manufactured, non-HLA-matched CAR cell therapy and will be evaluated in phase 1 trials against B cell malignancies shortly.
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