Clinical Grade Generation of T-Helper-1-Driven Polyclonal T-Cell Populations for Adoptive Immunotherapy Against Tumor Associated Antigens

Abstract 4314

Adoptive T cell therapy has been shown an option to treat patients with malignancies. In contrast to vaccinations, T cells for adoptive T-cell therapy are generated ex vivo to be re-infused into the recipient. This enables treatment of immunocompromized hosts and use of allogeneic T cells to exploit graft versus tumor effects. Adoptive T-cell therapy involving CD4⁺ T-helper cells (Th cells), intends to induce sustained T-cell responses in vivo. The Th1 cytokine interferon-gamma (IFN-γ) has not only an effect in orchestrating cytotoxic T-cell reponses, IFN-γ by itself has antitumor effects. Transferring T cells in a lymphopenic host furthermore eliminates regulatory T cells (Tregs) and offers access to homeostatic cytokines. The aim of our study was the translation of preclinical data into a GMP conform clinical scale protocol to generate specific T cells for adoptive T-cell therapy against tumor associated antigens. Large scale generations of NY-ESO-1 specific T cells was performed according to current GMP regulations in a GMP facility. In brief, peripheral blood mononuclear cells from healthy donors were primed with an overlapping NY-ESO-1 15-mer peptide mix. The priming was done in the presence of IL-7 and IL-2. T cells were enriched using IFN-γ capture technique and expanded for two weeks in autologous culture conditions with IL-7, IL-15 and IL-2. T-cell specificity, function and proliferation capacity was analyzed by flow cytometry. The T-cell products showed high numbers of specifically IFN-γ⁺, TNF-alpha⁺ T cells. Tolerance inducing cytokines like IL-10 were absent. Enrichment of Tregs was excluded. Both, CD4⁺ and CD8⁺ T cells with an effector memory phenotype proliferated in response to NY-ESO-1. CD107a assays demonstrated cytotoxic capacities of T cells. The T-cell product did not include alloreactive T cells. In summary GMP-conform generation of NY-ESO-1 specific T cells was established. Although tumor associated antigens are potential self antigens, it is possible to induce a functional Th1 response in peripheral blood T cells from healthy donors. Adoptive T-cell therapy against tumor associated antigens could have implications for multiple tumor entities in autologous as well as allogeneic treatment approaches.