T cells expressing CD5/CD7 bispecific chimeric antigen receptors with fully human heavy-chain-only domains mitigate tumor antigen escape

摘要

Bispecific chimeric antigen receptor T-cell(CAR-T)therapies have shown promising results in clinical trials for advanced B-cell malignancies.However,it is challenging to broaden the success of bispecific CAR-T therapies to treat refractory/relapse(r/r)T-cell leukemia/lymphoma because targeting multiple T-cell-expressing antigens leads to exacerbated CAR-T cell fratricide and potential safety concerns.Fully human heavy chain variable(FHVH)antibodies that specifically target CD5 or CD7 were screened and constructed to CD5/CD7 bispecific CARs.A truncated Epidermal growth factor receptor were integrated into CAR constructs to address safety concerns.To tackle the fratricidal issue of CAR-T cells targeting T-cell-pan marker(s),CRISPR/Cas9-based CD5 and CD7 genes knockout were performed before lentiviral transduction of bispecific CARs.Functional comparison between different bispecific CAR structures:tandem CARs and dual CAR were performed in vitro and in vivo to determine the optimal construct suitable for addressing T-cell malignancy antigen escape in clinical setting.Knockout of CD5 and CD7 prevents fratricide of CD5/CD7 bispecific CAR-T cells,and FHVH-derived CD5/CD7 bispecific CAR-T cells demonstrate potent antitumor activity in vitro and in vivo.The fratricide-resistant FHVH-derived CD5/CD7 bispecific CAR-T cells have potent antitumor activity against T-cell malignancies,and tandem CARs are more effective than dual CAR in preventing tumor escape in heterogeneous leukemic cells.The meaningful clinical efficacy and safety of tandem CD5/CD7 CAR-T cells deserve to be explored urgently.