Gene Therapy-Mediated Reprogramming Tumor Infiltrating T Cells Using IL-2 and Inhibiting NF-κB Signaling Improves the Efficacy of Immunotherapy in a Brain Cancer Model

• DOI: 10.1007/s13311-012-0144-7
• Publication Date: 2012-09-20T16:04:03Z
• Authors: Yohei Mineharu; AKM Ghulam Muhammad; Kader Yagiz; Marianela Candolfi; Kurt M. Kroeger; Weidong Xiong; Mariana Puntel; Chunyan Liu; Eva Levy; Claudia Lugo; Adrina Kocharian; James P. Allison; Michael A. Curran; Pedro R. Lowenstein; Maria G. Castro
• Keywords: 0301 basic medicine; T-Lymphocytes; Genetic Vectors; GLIOBLASTOMA; GENE THERAPY; Antiviral Agents; Adenoviridae; 03 medical and health sciences; HSV1-TK; Lymphocytes, Tumor-Infiltrating; https://purl.org/becyt/ford/3.4; ADENOVIRAL VECTORS; Animals; Humans; https://purl.org/becyt/ford/3; IMMUNOTHERAPY; Ganciclovir; Brain Neoplasms; NF-kappa B; Membrane Proteins; Dendritic Cells; Genetic Therapy; Recombinant Proteins; Rats; 3. Good health; Disease Models, Animal; Interleukin-2; Immunotherapy; Glioblastoma; Signal Transduction

Immune-mediated gene therapy using adenovirus expressing Flt3 ligand and thymidine kinase followed by ganciclovir administration (Flt3/TK) effectively elicits tumor regression in preclinical glioma models. Herein, we assessed new strategies to optimize Flt3L/TK therapeutic efficacy in a refractory RG2 orthotopic glioblastoma model. Specifically, we aimed to optimize the therapeutic efficacy of Flt3L/TK treatment in the RG2 model by overexpressing the following genes within the brain tumor microenvironment: 1) a TK mutant with enhanced cytotoxicity (SR39 mutant TK), 2) Flt3L-IgG fusion protein that has a longer half-life, 3) CD40L to stimulate DC maturation, 4) T helper cell type 1 polarizing dendritic cell cytokines interleukin-12 or C-X-C motif ligand 10 chemokine (CXCL)-10, 5) C-C motif ligand 2 chemokine (CCL2) or C-C motif ligand 3 chemokine (CCL3) to enhance dendritic cell recruitment into the tumor microenvironment, 6) T helper cell type 1 cytokines interferon-γ or interleukin-2 to enhance effector T-cell functions, and 7) IκBα or p65RHD (nuclear factor kappa-B [NF-κB] inhibitors) to suppress the function of Foxp3+ Tregs and enhanced effector T-cell functions. Anti-tumor immunity and tumor specific effector T-cell functions were assessed by cytotoxic T lymphocyte assay and intracellular IFN-γ staining. Our data showed that overexpression of interferon-γ or interleukin-2, or inhibition of the nuclear factor kappa-B within the tumor microenvironment, enhanced cytotoxic T lymphocyte-mediated immune responses and successfully extended the median survival of rats bearing intracranial RG2 when combined with Flt3L/TK. These findings indicate that enhancement of T-cell functions constitutes a critical therapeutic target to overcome immune evasion and enhance therapeutic efficacy for brain cancer. In addition, our study provides novel targets to be used in combination with immune-therapeutic strategies for glioblastoma, which are currently being tested in the clinic.