264. Immune Gene-Therapy of Cancer Using Redirected Naïve or Effector Lymphocytes

Abstract

In order to expand the recognition spectrum of effector lymphocytes and redirect them in non-individual restricted manner to predefined targets, we have developed the ‘T-body’ approach for adoptive cancer immunotherapy, using chimeric receptor genes with antibody-type specificity. The modular structure of the chimeric receptor containing ecto-, scFv and spacer, transmembrane and cytoplasmic domains enabled its engineering to fit a desired task.To target human breast and prostate tumors we have constructed several scFv's from mAbs recognizing the erbB-2 growth factor receptor that is over-expressed on several human cancer cells. To achieve full T cell activity against target cells that escape the immune surveillance, we combined both antigen receptor signal with the co- stimulatory signal required for full T cell activation by inserting the cytoplasmic, transmembrane and part of the extracellular regions of the CD28 molecule in-between the scFv recognition unit and the gamma or zeta signaling domains. In two experimental models, s.c. and pulmonary metastases, we show that transgenic mice expressing the erbB2-specific tripartite chimeric receptor (TPCR) were able to reject the erbB2+ tumors. Notably, adoptive transfer of naïve T cells derived from these transgenic mice show specific elimination of orthotopic mammary tumors with no requirement of either active vaccination or pre-conditioning. These findings suggest an important role the CD28 plays in the chimeric receptor function. In the SCID mouse system we demonstrated the ability of genetically engineered human T-bodies, administered either intratumoraly or systemically, to retard the growth of, and even reject, breast cancer xenografts in significant number of mice.Taken together, these studies demonstrate the advantage of the TPCR in the redirection of mature, primed T-cells (e.g. transduced by the TPCR) and unprimed cells (e.g. derived from transduced hematopoietic stem cells) for the immunotherapy of solid tumors. In order to expand the recognition spectrum of effector lymphocytes and redirect them in non-individual restricted manner to predefined targets, we have developed the ‘T-body’ approach for adoptive cancer immunotherapy, using chimeric receptor genes with antibody-type specificity. The modular structure of the chimeric receptor containing ecto-, scFv and spacer, transmembrane and cytoplasmic domains enabled its engineering to fit a desired task. To target human breast and prostate tumors we have constructed several scFv's from mAbs recognizing the erbB-2 growth factor receptor that is over-expressed on several human cancer cells. To achieve full T cell activity against target cells that escape the immune surveillance, we combined both antigen receptor signal with the co- stimulatory signal required for full T cell activation by inserting the cytoplasmic, transmembrane and part of the extracellular regions of the CD28 molecule in-between the scFv recognition unit and the gamma or zeta signaling domains. In two experimental models, s.c. and pulmonary metastases, we show that transgenic mice expressing the erbB2-specific tripartite chimeric receptor (TPCR) were able to reject the erbB2+ tumors. Notably, adoptive transfer of naïve T cells derived from these transgenic mice show specific elimination of orthotopic mammary tumors with no requirement of either active vaccination or pre-conditioning. These findings suggest an important role the CD28 plays in the chimeric receptor function. In the SCID mouse system we demonstrated the ability of genetically engineered human T-bodies, administered either intratumoraly or systemically, to retard the growth of, and even reject, breast cancer xenografts in significant number of mice. Taken together, these studies demonstrate the advantage of the TPCR in the redirection of mature, primed T-cells (e.g. transduced by the TPCR) and unprimed cells (e.g. derived from transduced hematopoietic stem cells) for the immunotherapy of solid tumors.