Nanobody-Engineered CLL-1 CAR T Cells: Optimizing Tumor-Specific Cytotoxicity and Minimizing Off-Tumor Toxicity

Area of Science:

• Immunology
• Hematology
• Oncology

Background:

• Acute myeloid leukemia (AML) is an aggressive cancer with poor prognosis.
• Chimeric antigen receptor (CAR) T-cell therapy shows promise but faces challenges in AML due to toxicities.
• Targeting myeloid-restricted antigens is crucial for effective AML immunotherapy.

Purpose of the Study:

• To develop and evaluate a nanobody-based CAR-T cell platform targeting the CLL-1 antigen for AML treatment.
• To compare the efficacy and safety of CLL-1 CAR-T cells with CD33 CAR-T cells.
• To assess the potential of nanobody CAR-T cells to overcome current limitations in AML immunotherapy.

Main Methods:

• Engineered nanobody CAR constructs targeting CLL-1 and CD33.
• IncuCyte real-time cytotoxicity assays.
• Serial tumor re-challenge assays.
• NSG xenograft models for in vivo efficacy evaluation.

Main Results:

• Both CLL-1 and CD33 CAR-T cells demonstrated potent anti-leukemic activity.
• CLL-1 CAR-T cells selectively targeted AML blasts while sparing normal hematopoietic progenitors.
• CLL-1 CAR-T cells maintained a favorable memory phenotype, proliferation, and viability.
• Cytokine release assays confirmed antigen-specific immune activation.

Conclusions:

• CLL-1-targeted nanobody CAR-T cells represent a promising precision immunotherapy for AML.
• This approach offers potent anti-leukemic activity with reduced off-target toxicity.
• Nanobody CAR-T cells have enhanced translational potential for improving AML patient outcomes.