Transplant and Autoimmune Therapy Using T-Cells Expressing Programmed Death Ligand-1 (PD-L1)

Transplant complications (graft rejection and graft-versus-host disease) and autoimmune diseases are primarily caused by T cell immune responses against normal host tissue or transplanted tissues. These disorders can lead to serious complications and may be chronic, debilitating, and fatal. Current treatment for these disorders is oftentimes not effective, and is typically associated with significant side effects, including global immune suppression, which increases the rate of infection and cancer. Hence, there is a need for new technologies to more specifically suppress the immune system for treatment of these diseases.

Programmed death (PD) ligand 1 (PD-L1) is an immune molecule present on regulatory T cells (Tregs), other suppressor cell populations, and tumor cells; the function of PD-L1 is to suppress the function of pathogenic T cells that express the PD1 receptor. Therefore, it has been hypothesized that the transfer of T cells that are enriched for PD-L1 expression might represent an effective method to suppress autoimmunity or transplant complications. Adoptive T cell therapy using Tregs is one such approach; however, this approach is limited due to the relative rarity of Tregs and their tendency to possess differentiation plasticity towards pathogenic T cell subsets such as the Th17 subset. Ex vivo co-stimulated and expanded effector T cells can be generated in sufficient numbers for cell therapy; however, such cells are not enriched for PD-L1 expression.

The current technology overcomes these limitations through transduction of co-stimulated T cells with a lentiviral expression vector that dictates T cell expression of PD-L1. In this method, the co-stimulated T cells acquire the immunosuppressant characteristics of Treg cells. The PD-L1 gene expression construct co-expresses a cell surface molecule (i.e., CD19 or CD34) that allows enrichment of the gene-modified T cells to high purity. Also the construct co-expresses another gene, TMPK, which acts as a safety cell fate switch because the TMPK can specifically activate the cytotoxic prodrug, AZT. By incorporation of this TMPK/AZT cell fate safety switch, the current technology will allow for PD-L1 therapeutic delivery, with subsequent elimination of the therapeutic cells in the event of toxicity. CRADA Opportunity: The Center for Cancer Research, Experimental Transplantation and Immunology Branch, is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize this technology. Please contact John D. Hewes, Ph.D. at 301-435-3121 or hewesj@mail.nih.gov for more information. Click here to view the NCI collaborative opportunity announcement.

Source: http://www.ott.nih.gov/Technologies/abstractDetails.aspx?RefNo=2163

Jennifer Garner Jennifer Gimenez Jennifer Love Hewitt Jennifer Morrison Jennifer ODell