Document Type : Original Article
Department of Cellular and Molecular Biology, Faculty of Biological Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
Department of Microbiology, Faculty of Biological Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
Department of Stem Cells and Developmental Biology, Cell Science Research Centre, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
4Pediatric Cell and Gene Therapy Research Center, Gene, Cell and Tissue Research Institute, Tehran University of Medical Sciences, Tehran, Iran
The clinical studies of acute myeloid leukaemia (AML) revealed that antigen escaping variants cause cancer recurrence even after treatment with chimeric antigen receptor (CAR)-T cells that target a single tumour antigen. Due to the heterogeneous expression of antigens on leukaemia blasts, we hypothesized that a novel bispecific CAR, directed to the folate receptor beta (FRβ)-binding single-chain variable fragment (scFv) and an IL3α-binding receptor (CD123) that has more expression in AML blasts, can decrease CAR-T cell exhaustion and increase the efficacy of CAR-T cells to prevent antigen escaping and consequent recurrence of AML.
Materials and Methods
In this experimental study, the survival, proliferation, and cytolysis of CAR-T cells remains suboptimal even with a costimulatory endodomain. Hence, we designed and constructed a tandem CAR that joins an FRβ and CD123 in the second generation retroviral vector to generate a bispecific tandem CAR (TanCAR-T cell).
TanCAR FRβ-CD123 T cells showed distinct binding to FRβ or CD123 expressing cells. They could lyse the leukaemia cell lines (66.1 ± 11%) comparable to the single CAR-T cells against these determinants. TanCAR FRβ- CD123 T cells simultaneously engaged FRβ and CD123, which promoted T cell activation in targeting and lysis of the examined leukaemia cell lines. TanCAR-T cell significantly induced interferon gamma (IFNγ) and interleukin 2 (IL-2) production more than single CAR-T cells, which produced a synergistic enhancement of TanCAR FRβ-CD123 T cell function when dual antigens faced simultaneously.
Dual-specific TanCAR FRβ-CD123 T cells showed therapeutic potential to improve AML control by co- engaging FRβ and CD123 molecules in a robust, divalent immune system. This strategy may be a useful therapeutic approach in patients with relapsed B-cell malignancies.