TNF-alpha gene therapy with myeloid progenitor cells lacks the toxicities of systemic TNF-alpha therapy

Gene therapy and active immune therapy of hematologic malignancies

Gene therapy for patients with hematologic malignancies, particularly chronic lymphocytic leukemia (CLL), have focused on transducing primary leukemia cells with a virus vector to express immune-stimulating genes which can induce and propagate a productive and clinically significant immune response against the malignant cells. A variety of replication-defective vectors has been studied to transduce genes for cytokines and function-associated surface molecules. Active vaccines have been developed in vitro, and their activity has been confirmed in clinical trials. Ongoing work aims to optimize this strategy and to identify the appropriate and optimal patient groups in which to apply vaccine therapy. Clinical trials also have provided insight into unexpected alternative mechanisms through which these strategies might provide a clinical benefit.

In vitro analysis of the antileukemic effect of tumor necrosis factor-alpha gene therapy with myeloid progenitor cells: the role of dendritic cells

We have previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) gene therapy with transgene-expressing myeloid progenitor cells (32DTNF-alpha) is effective in inhibiting the progression of leukemia with a lethal dose of murine 32Dp210 myeloid leukemia cells. Because TNF-alpha has been shown to induce the activation and maturation of dendritic cells (DCs), we investigated the effect of TNF-alpha secreted by transduced cells (32DTNF-alpha cells) on the activation of DCs and their role in the production of antileukemic cytotoxic T lymphocytes (CTLs). We demonstrate that administration of 32DTNF-alpha cells to the mice enhances the allo-stimulatory capacity of the splenic (CD11c+) and bone marrow-derived DCs in both mixed leukocyte response and CTL development. The enhanced allo-stimulatory capacity of splenic DCs from mice injected with 32DTNF-alpha cells correlated with increase in the cell-surface expression of the costimulatory molecules CD40, CD80, CD86, and major histocompatibility complex (MHC) class II molecules (I-Ak), and production of interleukin-12 (IL-12). Furthermore, administration of 32DTNF-alpha cells during immunization with irradiated 32Dp210 leukemia cells augmented the capacity of splenic DCs to stimulate antileukemic CTL response in spleen cells. Collectively, these data suggest that in vivo production of TNF-alpha by transduced cells enhances the phenotypic and functional activation of DCs, resulting in induction of a stronger antileukemic cytotoxic T-cell immune response.