CRISPR/Cas9-engineered universal CD123/B7-H3 tandem CAR-T cell for the treatment of acute myeloid leukemia.

BACKGROUND: Autologous chimeric antigen receptor T (CAR-T) cell therapy has demonstrated efficacy in the treatment of acute myeloid leukemia (AML). Nevertheless, the intrinsic characteristics of autologous therapy, such as extended manufacturing timelines and patient-specific limitations, contribute to delays in treatment availability. More critically, relapse due to antigen escape following single-targeted CAR-T therapy constitutes a significant clinical obstacle. To address the dual challenges of delayed treatment accessibility and antigen escape relapse, this study proposes the development of universal tandem CAR-T cells. These cells, engineered to target CD123 and B7-H3 through clustered regularly interspaced short palindromic repeats (CRISPR) gene editing technology, represent an innovative therapeutic strategy for AML. METHODS: In this study, an immune phage display nanobody library was developed for the purpose of screening CD123-specific nanobodies. The CRISPR/CRISPR-associated protein 9 (CRISPR/Cas9) gene editing system was utilized to disrupt the T-cell receptor alpha chain ( TRAC ) and B2M genes present in T cells, resulting in the generation of universal CD123/B7-H3 bispecific universal CAR-T (UCAR-T) cells. The efficacy of these dual-specific UCAR-T cells in combating tumors was subsequently assessed through in vitro and in vivo experiments. RESULTS: Through four rounds of panning against CD123 from an immunized camelid VHH library, we identified 21 antigen-specific nanobodies. Tandem bispecific UCAR-T engineered with these binders demonstrated CAR transduction efficiencies ranging from 82% to 87%. In vitro functional profiling revealed a significantly enhanced cytotoxicity of bispecific UCAR-Ts against CD123 + /B7-H3 + AML cell lines when compared to single-target constructs, while effectively regulating the secretion of effector cytokines (IL-2, IFN-γ, TNF-α). In AML xenograft models, treatment with bispecific UCAR-T notably inhibited tumor progression, extended the survival of tumor-bearing mice with recurrence-free persistence throughout the observation period, and did not result in significant body weight loss or cytokine release syndrome. CONCLUSIONS: The findings of the study address the issue of tumor antigen evasion in the treatment of AML, circumvent certain constraints associated with autologous CAR-T cell therapy, and offer novel insights and strategies for managing AML.