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Peter Pyrko, Weijun Wang, Francis S. Markland, Steve D. Swenson, Stephanie Schmitmeier, Axel H. Schönthal and Thomas C. Chen

Object

Malignant gliomas are not curable because of diffuse brain invasion. The tumor cells invade the surrounding brain tissue without a clear tumor—brain demarcation line, making complete resection impossible. Therapy aimed at inhibition of invasion is crucial not only for prevention of tumor spread, but also for selectively blocking migrating cells that may be more resistant to chemotherapy and radiation. Recently, investigations have shown that the snake venom disintegrin contortrostatin specifically binds to certain integrins on the surface of glioma cells and thereby inhibits their interaction with the extracellular matrix (ECM), resulting in a blockage of cell motility and invasiveness. To translate these in vitro findings into clinical settings, the authors examined the effect of contortrostatin on glioma progression in a rodent model.

Methods

Athymic mice were intracranially or subcutaneously injected with U87 glioma cells, and the effect of intratumorally administered contortrostatin on tumor progression and animal survival was then studied. In addition, the authors evaluated the pharmacological safety of contortrostatin use in the brains of tumor-free animals.

Conclusions

The results demonstrate that contortrostatin is able to inhibit tumor growth and angiogenesis and to prolong survival in a rodent glioma model. Moreover, contortrostatin appears to be well tolerated by the animal and lacks obvious neurotoxic side effects. Thus, contortrostatin may have potential as a novel therapeutic agent for the treatment of malignant gliomas.

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Weijun Wang, Steve Swenson, Hee-Yeon Cho, Florence M. Hofman, Axel H. Schönthal and Thomas C. Chen

OBJECTIVE

Many pharmaceutical agents are highly potent but are unable to exert therapeutic activity against disorders of the central nervous system (CNS), because the blood-brain barrier (BBB) impedes their brain entry. One such agent is bortezomib (BZM), a proteasome inhibitor that is approved for the treatment of multiple myeloma. Preclinical studies established that BZM can be effective against glioblastoma (GBM), but only when the drug is delivered via catheter directly into the brain lesion, not after intravenous systemic delivery. The authors therefore explored alternative options of BZM delivery to the brain that would avoid invasive procedures and minimize systemic exposure.

METHODS

Using mouse and rat GBM models, the authors applied intranasal drug delivery, where they co-administered BZM together with NEO100, a highly purified, GMP-manufactured version of perillyl alcohol that is used in clinical trials for intranasal therapy of GBM patients.

RESULTS

The authors found that intranasal delivery of BZM combined with NEO100 significantly prolonged survival of tumor-bearing animals over those that received vehicle alone and also over those that received BZM alone or NEO100 alone. Moreover, BZM concentrations in the brain were higher after intranasal co-delivery with NEO100 as compared to delivery in the absence of NEO100.

CONCLUSIONS

This study demonstrates that intranasal delivery with a NEO100-based formulation enables noninvasive, therapeutically effective brain delivery of a pharmaceutical agent that otherwise does not efficiently cross the BBB.

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Weijun Wang, Nian-Ling Zhu, Jason Chua, Steve Swenson, Fritz K. Costa, Stephanie Schmitmeier, Barbara A. Sosnowski, Toshiaki Shichinohe, Noriyuki Kasahara and Thomas C. Chen

Object. Adenovirus vector (AdV)—mediated gene delivery has been recently demonstrated in clinical trials as a novel potential treatment for malignant gliomas. Combined coxsackievirus B and adenovirus receptor (CAR) has been shown to function as an attachment receptor for multiple adenovirus serotypes, whereas the vitronectin integrins (αvβ3 and αvβ5) are involved in AdV internalization. In resected glioma specimens, the authors demonstrated that malignant gliomas have varying levels of CAR, αvβ3, and αvβ5 expression.

Methods. A correlation between CAR expression and the transduction efficiency of AdV carrying the green fluorescent protein in various human glioblastoma multiforme (GBM) cell lines and GBM primary cell lines was observed. To increase transgene activity in in vitro glioma cells with low or deficient levels of CAR, the authors used basic fibroblast growth factor (FGF2) as a targeting ligand to redirect adenoviral infection through its cognate receptor, FGF receptor 1 (FGFR1), which was expressed at high levels by all glioma cells. These findings were confirmed by in vivo study data demonstrating enhanced transduction efficiency of FGF2-retargeted AdV in CAR-negative intracranial gliomas compared with AdV alone, without evidence of increased angiogenesis.

Conclusions. Altogether, the results demonstrated that AdV-mediated gene transfer using the FGF2/FGFR system is effective in gliomas with low or deficient levels of CAR and suggested that FGF2-retargeting of AdV may be a promising approach in glioma gene therapy.