49P - Highly potent novel armoured IL13Ra2 CAR T cell targeting glioblastoma

Background

Glioblastoma (GBM) remains one of the most lethal brain cancers. CAR T cells targeting IL13Rα2 have shown tumour shrinkage and extended survival in some patients, but challenges remain, such as sustaining T-cell activity and overcoming the tumour microenvironment (TME). Here we show a new “armoured” CAR T (NS007) to better tackle the immunosuppressive TME and enhance persistence in solid tumours.

Methods

We developed a highly specific humanized single-domain antibody (VHH) targeting IL13Rα2. Human T cells were engineered using a single retroviral vector encoding a fourth-generation CAR with 4 additional elements: - 1) A component that blocks TGF-beta signalling - 2) A constitutive receptor that drives cellular proliferation - 3) an engineered single-chain IL-12 -4) a suicide gene for controlled cell elimination. These armoured CAR-T cells NS007, were evaluated for their cytolytic capacity against IL13Rα2-expressing cancer cells and ability to counteract immunosuppression both in vitro and in vivo.

Results

NS007 outperformed non-armoured CAR T cells, exhibiting greater tumour cell destruction, better proliferation, and longer persistence. In co-cultures, NS007 cells were less sensitive to TGF-β-mediated suppression, while also activating bystander NK and T cells via an attenuated IL-12. Furthermore, the engineered IL-12 showed no toxicity in syngeneic mouse models. The suicide gene, activated by an FDA-approved drug (Trastuzumab Emtansine), successfully eliminated NS007 cells both in vitro and in vivo. NS007’s efficacy, survival, and safety were confirmed in an aggressive orthotopic U87-MG GBM model using ultra-low doses (<10000 cells).

Conclusions

Our enhanced single cassette CAR T-cell design demonstrates key improvements: - enhanced tumour-killing capacity - resilience against TGF-β - extended persistence in the host - Ability to activate the host innate immune system through an attenuated cytokine - Ability to be turned off through the activation of a suicide gene These advancements represent a significant step forward in addressing challenges associated with CAR T-cell therapy in solid tumors, particularly for GBM treatment.

Legal entity responsible for the study

Chimeris UK.

Funding

Chimeris UK.

Disclosure

M. Mangolini, S. Srivastava, E. Souster, Y. Yang, R. Karatill, L. Schultz, B. Ma, D. Pombal, S. Cordoba, S. Onuoha: Financial Interests, Personal, Stocks/Shares: Chimeris Uk. A. Ramon, M. Greenig, P. Sormanni: Financial Interests, Personal, Advisory Role: Chimeris Uk.