Adoptive T cell immunotherapy using chimeric antigen receptor against a novel cancer target Axl (VAC11P.1007)

The Axl protein belongs to a subfamily of receptor tyrosine kinase and has been implicated in a large variety of cancers like colorectal, prostate, mesothelioma, breast, etc., beginning from its overexpression initially detected in chronic myeloid leukemia. Hence Axl presents as a novel and promising target for multiple cancer models. Meanwhile chimeric antigen receptor (CAR) is already a developed platform technology used in genetically modified T cells in order to make them recognize and elicit an immune response against cancer cells. Here we designed 3 single-chain variable fragments from existing monoclonal antibodies against Axl and constructed them into third-generation CARs. For testing, we transduced these CARs into Jurkat T cells and primary CD4 T cells. We cultured the cells in different doses of Axl and assayed the level of their activation using flow cytometry and ELISA. All 3 CARs demonstrated functional efficacy in being able to recognize the antigen and produced successful activation. This was detected by increase in GFP expression, cloned downstream of the NFAT promoter in the Jurkat T cell line. Furthermore the primary T cell experiment demonstrated increased secretion of IFNγ for all 3 CARs and IL-2 for 2 CARs. Our study confirmed the successful construction of 3 new therapeutic CARs against the novel cancer antigen, Axl, with varying levels of activation. This can now be utilized in a switchable CAR system to deliver a tunable therapeutic immune response.