Rejection of Experimental Hodgkins Lymphoma by T-cells Engineered with a CD19 Chimeric Antigen Receptor

T cells engineered to express chimeric receptors combining an external antibody binding domain with the CD3ζ T cell receptor (TCR) internal domain for triggering cell activation are being used for immunotherapeutic targeting of tumour cells in a non-HLA restricted manner. In this study we transduced T cells with a CD19-cTCR construct containing a truncated CD34 gene (tCD24) marker and used these to target the B cell antigen CD19 on the surface of a Hodgkin’s lymphoma (HL) cell line (L591) both in vitro and in vivo. Levels of tCD34 expression in transduced peripheral blood mononuclear cells ranged from 6-20% and this was increased to 82% after selection for trasnduced tCD34+ cells. In vitro cytotoxicity testing on a CD19+ HL cell line (L591) showed specific cell lysis initiated by the CD19-cTCR transduced PBMCs. In tumour prevention experiments severe combined immunodeficient (SCID) mice were inoculated with L591 HL cells subcutaneously (sc), and simultaneously inoculated with transduced CD19-cTCR T cells either sc or intravenously (iv). None of the 6 mice which received CD19-cTCR transduced T cells sc developed tumours compared to 4/6 (67%) iv inoculated and 17/22 (77%) un-inoculated controls (p=0.001). In tumour treatment experiments, transduced CD19-cTCR T cells were given iv to SCID mice 3-9 days after sc tumour formation. Whereas tumours progressed in all control uninoculated animals, complete tumour regression occurred with all treated mice surviving over 65 days (p=0.011). Time course experiments showed infiltrating CD19-cTCR transduced T cells (tCD34+) in tumour tissue at 11 and 18 days post inoculation, reaching a maximum of 41% of cells. These results suggest that CD19 could be a target for the immunotherapy of HL and that further preclinical studies are warranted.