Abstract

CAR-T cells represent a therapeutic breakthrough for the treatment of cancers. These therapeutic tools are obtained in vitro by introducing a chimeric receptor recognizing a tumor antigen (CAR) into T lymphocytes isolated from the patient’s blood. The preparation of CAR-T cells requires a lymphocyte activation step to enable CAR expression, most often performed by lentiviral infection, and to induce proliferation in order to obtain a sufficient quantity of cells. While this immunotherapy has produced remarkable results in the regression of hematological malignancies, it is still far from producing a satisfactory response against solid tumors, and around 40% of patients treated for hematological malignancies relapse. While several tumor escape mechanisms have been identified to explain these failures, more and more evidence is questioning the state of differentiation of the CAR-expressing T cells. Some studies suggest that the manufacturing protocol, and more specifically the in vitro activation step, is counterproductive, reducing the cells' ability to engraft in the host and minimizing CAR-T cells activity.

My team studies the PI3K/Akt/FOXO1 signaling pathway in T lymphocytes, downstream of the TCR. The team has recently shown that pharmacological inhibition of FOXO1 transcriptional activity by AS1842856 leads to reprogramming of T cell metabolism, associated with a quiescence exit without proliferation. This cycle entry allows T lymphocytes to be infected by lentiviruses without any prior activation.

This was the background to my thesis work. I have shown that FOXO1 inhibition potentiates the immune functions of T lymphocytes in terms of cytotoxicity, survival, proliferation and migration, and I have assessed the relevance of using FOXO1 inhibition to establish a new type of CAR-T cells, generated in the absence of any in vitro activation. The results show that non-activated CAR-T cells, obtained by lentiviral infection enabled by treatment with AS1842856, display superior anti-tumor activity compared to CAR-T cells obtained classically in two human tumor xenograft models: one using a subcutaneously injected human pancreatic tumor and the other derived from a human lung tumor with an orthotopic localization.

Key words: FOXO1, AS1842856, CAR-T cells, T cell signaling, anti-tumor therapy