CYAD-02: Enhancing CAR T-Cell Therapy with Next-Gen NKG2D Platform and shRNA Co-expression for Sustained Anti-Tumor Activity

The NKG2D receptor, crucial for activating natural killer (NK) cells, binds to ligands (NKG2DL) often overexpressed in cancer. CYAD-01 is a CAR T-cell therapy that uses the NKG2D receptor linked to CD3ζ to target various tumors. Early Phase I clinical trial results for r/r AML and MDS patients showed promising responses.

Challenges in CAR T-cell therapy include producing sufficient cells for treatment. Previous work found that blocking antibodies and a PI3K inhibitor could enhance cell yield by targeting NKG2D ligands transiently expressed on activated T cells. This study explored the use of shRNA technology to regulate NKG2DL expression on CYAD-01 cells, aiming to boost the anti-tumor effects of the next-generation CAR T-cells, CYAD-02.

Molecular and cellular analyses pinpointed MICA and MICB as key NKG2DL likely contributing to fratricide. A single shRNA was identified to target both, reducing their expression. This shRNA was integrated into the CAR vector to create CYAD-02. Truncated NKG2D receptor versions were also made to study receptor activity.

In an AML preclinical model, CYAD-02 cells showed better persistence and anti-tumor effects than CYAD-1 cells. The presence of MICA and MICB on activated T-cells during manufacturing suggested that reducing their expression could improve CAR T-cell in vivo persistence.

CYAD-02 cells, made with a vector encoding the NKG2D CAR and the shRNA targeting MICA and MICB, showed a 3-fold increase in expansion during culture without the need for a blocking antibody. In immunosuppressed mice, CYAD-02 demonstrated a 10-fold higher engraftment and significantly extended mouse survival in an aggressive AML model.

The study concludes that CYAD-02, with its single vector approach and improved culture techniques, shows increased persistence and potent anti-tumor activity. With the FDA's acceptance of the IND application, a Phase 1 clinical trial for r/r AML and MDS treatment is planned for early 2020.