Intracranial therapy of glioblastoma with the fusion protein DTIL13 in immunodeficient mice

Abstract

A fusion protein consisting of human interleukin-13 and the first 389 amino acids of diphtheria toxin was assembled in order to target human glioblastoma cell lines in a murine intracranial model. In vitro studies to determine specificity indicated that the protein called DTIL13 was highly selective for human glioblastoma. In vivo, the maximum tolerated dose of DTIL13 was 1 lg/injection given every other day and repeated for 3 days. Doses that exceeded this amount resulted in weight loss and liver damage as determined by histology and enzyme assay. Experiments in IL-4 receptor knockout mice revealed that liver toxicity was receptorrelated. This same dose given to nude mice with established U373 MG brain tumors resulted in significant reductions in tumor volume and significantly prolonged survival (p < 0.0001). Magnetic resonance imaging (MRI) proved to be extremely useful in (i) determining the ability of DTIL13 to reduce tumor size and (ii) for studying toxicity since diffusion-weighted and gradient echoweighted MRI revealed that vascular leak syndrome was not a limiting toxicity at this dose. These results suggest that DTIL13 is as effective in an intracranial rodent model as it was in a flank model in previous studies and that DTIL13 might be an effective treatment for glioblastoma multiforme. ' 2005 Wiley-Liss, Inc.Key words: diphtheria toxin; glioblastoma; interleukin-13; brain tumor; immunotoxin Glioblastoma multiforme (GBM) is an incurable, heterogeneous, high-grade astrocytic glioma, thought to originate from glial nonneuronal cells. 1 More recent studies have identified a subpopulation of cancer stem-cells within GBM that retain the capacity for self-renewal and the ability to differentiate into a phenotypically diverse population of cells. 2-4 With a 2-year-patient survival rate of <30%, 5 effective treatment has been hindered by the lack of tumor-specific markers in the majority of patients. Recently, the IL-13 receptor (IL-13R) has been found to be overexpressed on cultured human GBM cell lines and surgical GBM specimens, but is not detectable in normal brain tissue. [6][7][8] Targeting the IL-13 receptor with an immunotoxin (IT) has already proven to have potential for treating brain tumors. [8][9][10][11][12] ITs are not mainstream pharmaceuticals, and treatment of systemic tumors with ITs has been limited by their failure to localize in tumor. The promise of these drugs is considerably greater for brain-cancer therapy, since IT can be directly administered intracranially. In an earlier study, we assembled an IL-13 IT made by fusing gene fragments encoding for human IL-13 and the first 389 amino acids of diphtheria toxin. 13 In vivo studies with this agent showed that it had a potent antitumor effect against IL-13R-positive GBM cells grown in the flanks of nude mice without significant toxicity.Although encouraging, the flank model has limitations as a model for intracranial therapy. First, intratumoral pressure within the flank model does not reach the pressures that occur in intracranial tumors ...

A Bispecific Recombinant Cytotoxin (DTEGF13) Targeting Human Interleukin-13 and Epidermal Growth Factor Receptors in a Mouse Xenograft Model of Prostate Cancer

“…injections. DTEGF13 was studied in a mouse model because human EGF and IL-13 (of DTEGF13) react with mouse EGFR and IL-13R, respectively (37,38). Figure 5A shows mean tumor volume data from the first experiment in which groups of mice (n = 4-5 per group) were given injections (2.5 Ag/injection) of DTEGF13, DTEGF, or DTIL13 on days 1, 3, 5, 8, 10, 12, 23, and 25.…”

The TWEAK receptor Fn14 is a potential cell surface portal for targeted delivery of glioblastoma therapeutics

“…124,125 Some of the “GB tumor-specific” cell surface proteins targeted by these constructs include podoplanin, 126 glycoprotein NMB, 127 ephrin type-A receptor 2 (EphA2), 128 urokinase plasminogen activator receptor (uPAR), 129,130 transferrin receptor (TfR), 131 EGFR, 132,133 the constitutively activated EGFRvIII deletion mutant, 134 IL-4Rα, 135,136 and IL-13Rα2. 86,137,138 Bispecific constructs targeting two different GB cell surface proteins have also been described. 124,125,139 Only one targeted toxin, IL13-PE38QQR (Cintredekin Besudotox), a fusion protein composed of human IL-13 and a truncated, mutated version of PE, has been evaluated in a large Phase III randomized GB clinical trial (the PRECISE trial).…”

CD133 negative glioma cells form tumors in nude rats and give rise to CD133 positive cells

“…Since cancer cell lines cultured in serum-containing medium is a widely used model system, we also characterized CD133 expression in 4 commonly used tumorgenic glioma cell lines 26,[31][32][33] (Fig. 5).…”