A Bidirectional EF1 Promoter System for Armoring CD19 CAR-T Cells with Secreted Anti-PD1 Antibodies

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• CAR T-cell therapy shows promise for B-cell malignancies but is limited by T-cell exhaustion.
• The PD-1/PD-L1 immune checkpoint axis is a key driver of T-cell exhaustion.

Purpose of the Study:

• To develop an "armored" CAR T-cell strategy to overcome T-cell exhaustion.
• To engineer CAR T-cells co-expressing a CD19-specific CAR and secreted anti-PD1 using a bidirectional promoter.

Main Methods:

• Utilized the Sleeping Beauty (SB) transposon system for vector engineering.
• Co-expressed CD19-specific CAR and secreted anti-PD1 (nivolumab-derived) using a bidirectional EF1 promoter.
• Evaluated CAR expression, proliferation, PD-1 expression, cytotoxicity, and persistence in vitro.

Main Results:

• Armored CAR T-cells exhibited robust CAR expression and enhanced proliferation.
• Secreted anti-PD1 reduced surface PD-1 expression on CAR T-cells.
• Engineered cells showed superior cytotoxicity against PD-L1-positive cells and enhanced persistence in serial rechallenge assays.

Conclusions:

• The bidirectional EF1 promoter efficiently generates multi-functional T-cells.
• Armoring CAR T-cells with secreted anti-PD1 antibodies enhances persistence and anti-tumor efficacy.
• This strategy offers a potent approach to improve CAR T-cell therapy for B-cell malignancies.