Molecular Imaging of Gene Expression and Efficacy following Adenoviral-Mediated Brain Tumor Gene Therapy

Cancer gene therapy is an active area of research relying upon the transfer and subsequent expression of a therapeutic transgene into tumor cells in order to provide for therapeutic selectivity. Noninvasive assessment of therapeutic response and correlation of the location, magnitude, and duration of transgene expression in vivo would be particularly useful in the development of cancer gene therapy protocols by facilitating optimization of gene transfer protocols, vector development, and prodrug dosing schedules. In this study, we developed an adenoviral vector containing both the therapeutic transgene yeast cytosine deaminase (yCD) along with an optical reporter gene (luciferase). Following intratumoral injection of the vector into orthotopic 9L gliomas, anatomical and diffusion-weighted MR images were obtained over time in order to provide for quantitative assessment of overall therapeutic efficacy and spatial heterogeneity of cell kill, respectively. In addition, bioluminescence images were acquired to assess the duration and magnitude of gene expression. MR images revealed significant reduction in tumor growth rates associated with yCD/5-fluorocytosine (5FC) gene therapy. Significant increases in mean tumor diffusion values were also observed during treatment with 5FC. Moreover, spatial heterogeneity in tumor diffusion changes were also observed revealing that diffusion magnetic resonance imaging could detect regional therapeutic effects due to the nonuniform delivery and/or expression of the therapeutic yCD transgene within the tumor mass. In addition, in vivo bioluminescence imaging detected luciferase gene expression, which was found to decrease over time during administration of the prodrug providing a noninvasive surrogate marker for monitoring gene expression. These results demonstrate the efficacy of the yCD/5FC strategy for the treatment of brain tumors and reveal the feasibility of using multimodality molecular and functional imaging for assessment of gene expression and therapeutic efficacy.

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Intratumoral Expression of MIP-1b Induces Antitumor Responses in a Pre-Established Tumor Model through Chemoattracting T Cells and NK Cells.

Blood ◽

10.1182/blood.v104.11.5268.5268 ◽

2004 ◽

Vol 104 (11) ◽

pp. 5268-5268 ◽

Cited By ~ 1

Author(s):

Yizhi Yu ◽

Xiaoling Luo ◽

Shuxun Liu ◽

Yuan Xie ◽

Xuetao Cao

Keyword(s):

Gene Therapy ◽

T Cells ◽

Nk Cells ◽

Cd8 T Cells ◽

Immune Cell ◽

Cancer Gene Therapy ◽

T Cell Subsets ◽

Therapeutic Effects ◽

Cancer Gene

Abstract Direct intratumoral introduction of therapeutic or regulatory genes is a developing technology with potential application for cancer gene therapy. Macrophage inflammatory protein-1 beta (MIP-1b) is a chemokine which can chemoattract immune cells such as T cells. In the present study, murine colorectal adenocarcinoma CT26 cells were transfected with a recombinant adenovirus (AdhMIP-1b) carrying the human MIP-1b gene. 24h post-transfection, hMIP-1b levels reached approximately 980 pg/ml in supernatants of 106 hMIP-1b-transfected CT26 cells. Moreover, the supernatants exhibited chemotactic activity for CD8+ T cells, CD4+ T cells, NK cells and immature DCs. Intratumoral injection of AdhMIP-1b significantly inhibited tumor growth and prolonged the survival time of tumor-bearing mice. Intratumoral hMIP-1b gene transfer also induced powerful tumor-specific CTL responses in vivo. The therapeutic effects of hMIP-1b gene therapy were greatly reduced following in vivo depletion of both CD4+ and CD8+ T cells, but were unaffected by depletion of single T cell subsets. Immune cell depletion experiments also revealed that NK cells played an important role in hMIP-1b-induced anti-tumor responses. These results suggest that intratumoral expression of hMIP-1b has the potential effect to induce host anti-tumor immunity and may prove to be a useful form of cancer gene therapy.

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