Work

Multi-Tumor-Antigen-Specific Cytotoxic T Lymphocytes For Therapy Of Hematologic Malignancies

Year: 2010

Type: article

Abstract: Tumor immunotherapy using in vitro expanded cytotoxic T lymphocytes (CTLs) can effectively treat virus-associated malignancies such as EBV +ve Hodgkin's Lymphoma. However, extension to non virus-associated malignancies has been complicated by the low frequency of circulating T-cells reactive against tumor-expressed antigens, which are often anergized or tolerized. To overcome T-cell anergy we activated T cells in the presence of a potent cytokine cocktail including IL12 (Th1 polarizing), IL7 and IL15 (pro-survival/-proliferative), and IL-6 (Treg inhibitory). We optimized the generation of polyclonal, multiTA-reactive CTLs by combining these cytokines with autologous dendritic cells nucleofected with combinations of DNA tumor antigen (TA)-encoding plasmids or pulsed with multiple TA pepmixes as APCs. The use of whole antigen increases the range of suitable patient HLA polymorphisms beyond those matched to single peptides, while targeting multiple antigens simultaneously reduces the risk of tumor immune evasion. Antigen combinations were chosen based on their tumor expression profile. To target lymphoma we grouped SSX2, Survivin, and MAGEA4 and were consistently able to generate multiTAA CTL directed against these three antigens (n=6 healthy donors). The lines were polyclonal comprising CD4+ (mean 57+/-7%) and CD8+ (mean 40+/-16%) T cells, with reactivity against SSX2, Survivin and MAGEA4 (median 345, 290 and 255 spot forming units (SFU)/1×106 CTL respectively in IFNg ELIspot, n=6). The CTLs were cytolytic against autologous SSX2 and Survivin pepmix-pulsed targets (mean 53% and 30% specific lysis, E:T 40:1) and against whole Survivin antigen-expressing fibroblasts (30% specific lysis, E:T 100:1) with no recognition of non-transduced control targets (9%) in a standard Cr51 release assay. For leukemia we targeted WT1, Prame, PR3, and Survivin and generated CTL lines with reactivity against WT1 (mean 733 SFU), PRAME (mean 555 SFU), PR3 (mean 145 SFU), and Survivin (mean 32 SFU/1×106 CTL), n=2. Hence it is feasible to generate single tumor specific CTL lines that target multiple tumor antigens simultaneously thereby reducing the risk of tumor escape and simplifying clinical application.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2009.12.086