Directed targeting of B-cell maturation antigen-specific CAR T cells by bioinformatic approaches: From in-silico to in-vitro

Aims: Chimeric Antigen Receptor (CAR) T-cell is a breakthrough in cancer immunotherapy. The primary step of successful CAR T cell therapy is designing a specific single-chain fragment variable (scFv). This study aims to verify the designed anti-BCMA (B cell maturation antigen) CAR using bioinformatic techniques with the following experimental evaluations. Main methods: Following the second generation of anti-BCMA CAR designing, the protein structure, function prediction, physicochemical complementarity at the ligand-receptor interface, and biding sites analysis of anti-BCMA CAR construct were confirmed using different modeling and docking server, including Expasy, I-TASSER, HDock, and PyMOL software. To generate CAR T-cells, isolated T cells were transduced. Then, anti-BCMA CAR mRNA and its surface expression were confirmed by real-time -PCR and flow cytometry methods, respectively. To evaluate the surface expression of anti-BCMA CAR, anti-(Fab ')2 and anti-CD8 antibodies were employed. Finally, anti-BCMA CAR T cells were co-cultured with BCMA+/-cell lines to assess the expression of CD69 and CD107a as activation and cytotoxicity markers. Key findings: In-silico results approved the suitable protein folding, perfect orientation, and correct locating of functional domains at the receptor-ligand binding site. The in-vitro results confirmed high expression of scFv (89 +/- 1.15% (and CD8 alpha (54 +/- 2.88%). The expression of CD69 (91.97 +/- 1.7%) and CD107a (92.05 +/- 1.29%) were significantly increased, indicating appropriate acti-vation and cytotoxicity. Significance: In-silico studies before experimental assessments are crucial for state-of-art CAR designing. Highly activation and cytotoxicity of anti-BCMA CAR T-cell revealed that our CAR construct methodology would be applicable to define the road map of CAR T cell therapy.