Overcoming Target Driven Fratricide for T Cell Therapy.

Area of Science:

• Immunology
• Cell Therapy
• Cancer Research

Background:

• Chimeric Antigen Receptor (CAR) T cells engineered with NKG2D gain specificity for stress ligands on cancer cells.
• Activated T cells also express these stress ligands, potentially causing self-killing (fratricide) of NKG2D-CAR T cells during manufacturing or cryopreservation.

Purpose of the Study:

• To investigate methods for preventing target-driven fratricide in NKG2D-CAR T cells.
• To establish efficient and reproducible manufacturing processes for clinical applications of NKG2D-CAR T cells.

Main Methods:

• Two strategies were employed: inclusion of a Phosphoinositol-3-Kinase inhibitor (LY294002) and antibody blockade of NKG2D.
• The timing of inhibitor and antibody addition during cell culture was optimized to fine-tune T cell characteristics.

Main Results:

• Both chemical inhibition and antibody blockade reduced T cell fratricide, with antibody blockade yielding higher cell numbers.
• Comparable NKG2D-CAR T cells were generated, with subtle differences in differentiation status observed.
• Optimized strategies were developed to produce potent NKG2D-CAR T cells, overcoming target-driven fratricide.

Conclusions:

• Target-driven CAR T fratricide can be overcome through targeted inhibition of NKG2D expression or broad enzyme inhibition.
• These strategies have been integrated into ongoing clinical trials for efficient and reproducible manufacturing of NKG2D-CAR T cells.