Engineering a fifth-generation CAR T cells to overcome PD-L1-mediated immunosuppression in lung cancer

Area of Science:

• Oncology
• Immunotherapy
• Biotechnology

Background:

• CAR T cell therapy shows promise in hematological cancers but faces challenges in solid tumors due to the immunosuppressive tumor microenvironment (TME).
• Program death ligand 1 (PD-L1) upregulation in non-small-cell-lung cancer (NSCLC) contributes to TME-mediated immunosuppression, hindering CAR T cell efficacy.

Purpose of the Study:

• To develop and evaluate a novel anti-folate receptor alpha (FRα) CAR T cell therapy, designated anti-FRα-CAR5, designed to secrete a PD-L1 blocking single chain variable fragment (scFv).
• To assess the potential of anti-FRα-CAR5 to overcome PD-L1-mediated immunosuppression in the TME for improved NSCLC treatment.

Main Methods:

• Human T lymphocytes were genetically engineered using a lentiviral vector to express anti-FRα-CAR5, featuring a fourth-generation CAR backbone and a secreted anti-PD-L1 scFv derived from atezolizumab.
• Surface expression of anti-FRα-CAR was confirmed using transfected HEK293T cells.
• The binding affinity and inhibitory activity of the secreted anti-PD-L1 scFv were tested against lung adenocarcinoma cell lines and PD-L1 monoclonal antibodies.

Main Results:

• The engineered anti-FRα-CAR5 T cells demonstrated successful surface expression and secretion of the anti-PD-L1 scFv.
• The secreted anti-PD-L1 scFv exhibited significant inhibitory activity (>80%) against PD-L1.
• Compared to a control CAR T cell (anti-FRα-CAR4), anti-FRα-CAR5 T cells showed enhanced expansion and cytotoxicity against FRα- and PD-L1-expressing lung cancer cell lines in vitro.

Conclusions:

• The fifth-generation anti-FRα-CAR5 T cell therapy represents a promising strategy to enhance CAR T cell efficacy in PD-L1-rich tumor microenvironments.
• These findings support further preclinical investigation of anti-FRα-CAR5 T cells as a potential therapeutic option for NSCLC patients.