53P - Novel ex-vivo manufacturing of transiently expressed armoured CAR T cells for glioblastoma

Background

Glioblastoma multiforme (GBM) is a highly aggressive malignant brain tumour with a median survival rate of < 2 years. Chimeric antigen receptor (CAR) T cells have shown limited success in GBM. The incorporation of armoured elements such as IL12 can enhance efficacy but introduce toxicity risks. In addition, prolonged manufacturing processes required for viral vector CAR T therapies often result in phenotypically exhausted products which further hinders their effectiveness.

Methods

We generated transiently expressed CAR T cells, ex vivo, using mRNA lipid nanoparticles (LNP). PBMCs are transfected using our novel Specific Engager Nanoparticle Delivery Reagent (SENDER) system that is specifically engineered to transfect T cells. The SENDER platform enabled targeted delivery of an IL13Rα2 CAR + IL12 based therapy to T cells that can be immediately cryopreserved.

Results

SENDER delivered IL13Rα2 CAR T cells demonstrated antigen specific cytotoxic function and IL2 production. CAR + IL12 cells further enhanced cytotoxicity by elevating the levels of IFN-g and activating the STAT4 pathway in NK cells and CD8⁺ T cells. More importantly, the expression of these components was transient and the level of IL12 enhancement was directly proportional to the concentration of IL12 mRNA used in the SENDER platform. Phenotypic analysis revealed SENDER LNP CAR T cells maintained a naïve and less exhausted phenotype compared to virus transduced cells. In an orthotopic murine model of GBM, PBMCs transfected with SENDER IL13Rα2 CAR + IL12 was able to eliminate tumour over multiple infusions demonstrating sustained efficacy and no toxicity with this approach.

Conclusions

Our SENDER platform enables CAR T cell production whilst minimising cell exhaustion and improving function. This process eliminated the need to purify, activate, transduce and expand T cells that are typically required for CAR T cell manufacturing, thus increasing the simplicity whilst reducing costs and production time. Potent armoured components can be expressed transiently and at controlled concentrations to maximise efficacy without causing toxicity.

Legal entity responsible for the study

Chimeris UK Ltd.

Funding

Chimeris UK Ltd.

Disclosure

S. Srivastava: Financial Interests, Institutional, Stocks/Shares: Chimeris Ltd. M. Mangolini, E. Souster, K. Hu, D. Pombal, L. Schultz, Y. Yang, B. Ma, S. Cordoba, S. Onuoha: Financial Interests, Institutional, Stocks/Shares: Chimeris UK Ltd.