Engineering a Programmed Death-Ligand 1-Targeting Monobody Via Directed Evolution for SynNotch-Gated Cell Therapy

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Programmed death-ligand 1 (PD-L1) is a key immunotherapy target but can cause on-target, off-tumor toxicity.
• Chimeric Antigen Receptor (CAR) T cell therapy faces challenges with solid tumors due to target heterogeneity and toxicity.

Purpose of the Study:

• To engineer a novel CAR T cell system targeting PD-L1 with enhanced tumor specificity and reduced toxicity.
• To develop a safety mechanism mitigating on-target, off-tumor effects in PD-L1-targeting CAR T cells.

Main Methods:

• Engineered a PD-L1-binding monobody (PDbody) with tumor microenvironment pH preference.
• Integrated a CD19-recognizing SynNotch IF THEN gate for conditional activation.
• Expressed the CD19-SynNotch PDbody-CAR system in human T cells for targeting PD-L1+ cancer cells.

Main Results:

• The engineered CAR T cells demonstrated high specificity and efficacy against PD-L1-expressing cancer cells in vitro.
• In vivo studies showed effective tumor growth restraint in a murine model.
• The system exhibited improved efficacy, proliferation, and reduced off-tumor toxicity compared to previous designs.

Conclusions:

• The CD19-SynNotch PDbody-CAR T cell system offers a promising strategy for solid tumor treatment.
• This approach enhances CAR T cell safety and efficacy by incorporating a conditional activation mechanism.
• Further development of such targeted and controlled immunotherapies holds potential for improved cancer treatment outcomes.