Rab5 Overcomes CAR T Cell Dysfunction Induced by Tumor-Mediated CAR Capture

Area of Science:

• Immunotherapy
• Cellular Biology
• Cancer Research

Background:

• Chimeric antigen receptor (CAR) T cell therapy faces challenges with T cell dysfunction and tumor escape due to continuous tumor interaction.
• Tumor cells can internalize CAR molecules, leading to loss of surface CARs and impaired T cell killing ability.

Purpose of the Study:

• To investigate the role of Rab5 in preventing CAR T cell dysfunction caused by CAR molecule internalization.
• To explore the potential of Rab5 to enhance CAR T cell activity and therapeutic efficacy against solid tumors.

Main Methods:

• Overexpression of Rab5 in CAR T cells.
• Assessment of clathrin-independent endocytosis and CAR surface expression.
• Analysis of membrane protrusions and T cell cytolytic activity.
• In vivo studies using humanized mice with mesothelin-expressing solid cancer.

Main Results:

• Rab5 overexpression augmented clathrin-independent endocytosis, preventing CAR loss from the T cell surface.
• Rab5 maintained membrane protrusions on CAR T cells after repeated tumor challenges, correlating with effective tumor clearance.
• Rab5-expressing CAR T cells showed improved activity and cleared refractory solid tumors in vivo by maintaining CAR surface expression.

Conclusions:

• Rab5 prevents CAR T cell dysfunction by inhibiting "CAR-jacking" and promoting CAR endocytic recycling.
• Rab5 expression enhances CAR T cell therapeutic efficacy against solid tumors, suggesting its potential clinical utility.