Trogocytosis and fratricide killing impede MSLN-directed CAR T cell functionality

Area of Science:

• Immunotherapy
• Oncology
• Cellular Biology

Background:

• Chimeric antigen receptor (CAR) T cell therapy faces challenges in solid tumors due to the tumor microenvironment and antigen heterogeneity.
• Mesothelin (MSLN) is a promising target for CAR T cell therapy in solid malignancies like ovarian cancer.
• Understanding in vitro mechanisms is crucial for improving MSLN-CAR T cell therapy outcomes.

Purpose of the Study:

• To compare the efficacy of CD28-costimulated (M28z) versus 4-1BB-costimulated (MBBz) MSLN-CAR T cells.
• To investigate mechanisms limiting MSLN-CAR T cell functionality in solid tumors.
• To identify potential strategies for enhancing CAR T cell therapy.

Main Methods:

• Comparison of cytolytic capacity of M28z and MBBz CAR T cells against tumor spheroids.
• Identification of CAR-mediated trogocytosis as a factor affecting CAR T cell therapy.
• Analysis of the relationship between antigen-dependent LAG-3 upregulation and CAR T cell function.

Main Results:

• CD28-costimulated MSLN-CAR T cells (M28z) exhibited superior cytolytic activity compared to 4-1BB-costimulated MSLN-CAR T cells (MBBz).
• M28z CAR T cells demonstrated enhanced efficacy against tumor spheroids with heterogeneous MSLN expression.
• CAR-mediated trogocytosis was identified as a mechanism causing fratricide and contributing to antigen heterogeneity.
• Antigen-dependent LAG-3 upregulation was correlated with reduced CAR T cell functionality.

Conclusions:

• CD28-costimulated MSLN-CAR T cells offer enhanced anti-tumor activity.
• CAR-mediated trogocytosis and LAG-3 upregulation represent significant hurdles for MSLN-CAR T cell therapy.
• Findings support the development of combinatorial treatment strategies to overcome therapeutic bottlenecks.