Modifications of the fiber in adenovirus vectors increase tropism for malignant glioma models.

Recombinant adenovirus (Ad) vectors provide a means of local, therapeutic gene delivery to a wide range of neoplasms. Ad-mediated gene therapy trials in malignant glioma models have been limited by the need for high viral titers and multiple dosages. In an attempt to improve Ad vector gene transfer, we studied human (U87, D54) and rodent (GL261, C6) malignant glioma cell lines transfected with various doses of unmodified Ad vectors (AdZ), Ad vectors that contain an alteration of the fiber-coat protein and that direct virus binding to heparan sulfate receptors (AdZ.F(pK7)), and Ad vectors with modifications of the fiber-coat protein that direct virus binding to alpha1, integrin cellular receptors (AdZ.F(RGD)). AdZ.F(pK7) increased the frequency of cells expressing the reporter gene, beta-galactosidase, and improved transduction by 2- to 20-fold compared with AdZ in U87, D54, and GL261 cells. In U87, D54, GL261, and C6 tumors, AdZ.F(pK7) increased gene transfer by 10- to 100-fold compared with AdZ. AdZ.F(RGD) increased gene expression in C6 xenografts compared with AdZ, but had reduced transduction compared with the C6 xenografts of AdZ in all other glioma tumors. These findings suggest that the increased tropisms resulting from alterations of the Ad vector fiber-coat protein as in AdZ.F(pK7) and AdZ.F(RGD) offer a feasible approach to improving in vitro and in vivo transduction efficiencies in certain malignant glioma cell lines.

Enhanced eradication of local and distant tumors by genetically produced interleukin-12 and radiation.

Ionizing radiation (IR) is frequently unsuccessful in the treatment of cancer because of local failure or distant metastases. The efficacy of systemically administered cytokines for cancer therapy is often limited by toxicity. We report that intratumoral injection of an adenoviral vector with interleukin-12 (IL-12) enhances local anti-tumor effects of irradiation (IR). We demonstrate that microscopic tumor growth at a distant site is suppressed following treatment of the primary tumor with adeno-murine IL-12 (Adm.IL-12). The results support a model in which the anti-angiogenic effects of IL-12 contribute to the local anti-tumor effects of radiation, while IL-12 induced immunity suppresses growth of microscopic tumors distant from the primary irradiated site. These data suggest that combining radiotherapy with IL-12 improves both local and distant tumor control compared to either treatment alone. Immunoradiotherapy may be employed in addition to or in place of current conventional therapies to increase local control and decrease distant tumor growth.

Radiation-inducible gene therapy.

The radiation-inducible chimeric genetic construct Egr-TNF alpha introduced into human xenografts produces cytotoxicity of infected tumor cells resulting in tumor growth inhibition. The interaction between Egr-TNF and radiation is selectively cytotoxic for the tumor microvasculature resulting in vascular thrombosis and tumor necrosis. Gene therapy combined with radiation therapy offers great potential for the treatment of localized human cancers.

Combined effects of angiostatin and ionizing radiation in antitumour therapy.

Angiogenesis, the formation of new capillaries from pre-existing vessels, is essential for tumour progression. Angiostatin, a proteolytic fragment of plasminogen that was first isolated from the serum and urine of tumour-bearing mice, inhibits angiogenesis and thereby growth of primary and metastatic tumours. Radiotherapy is important in the treatment of many human cancers, but is often unsuccessful because of tumour cell radiation resistance. Here we combine radiation with angiostatin to target tumour vasculature that is genetically stable and therefore less likely to develop resistance. The results show an antitumour interaction between ionizing radiation and angiostatin for four distinct tumour types, at doses of radiation that are used in radiotherapy. The combination produced no increase in toxicity towards normal tissue. In vitro studies show that radiation and angiostatin have combined cytotoxic effects on endothelial cells, but not tumour cells. In vivo studies show that these agents, in combination, target the tumour vasculature. Our results provide support for combining ionizing radiation with angiostatin to improve tumour eradication without increasing deleterious effects.

Adenoviral TNF-alpha gene therapy and radiation damage tumor vasculature in a human malignant glioma xenograft.

We evaluated the antitumor effects of ionizing radiation and tumor necrosis factor-alpha (TNF-alpha) gene therapy in human malignant glioma (D54) xenografts. An adenoviral vector (Ad5) containing DNA sequences of the Egr-1 promoter was linked to a cDNA encoding the TNF-alpha gene (Ad. Egr-TNF). Athymic nude mice bearing D54 xenografts received intratumoral injections of Ad.Egr-TNF or the null vector (Ad.null), with and without fractionated radiation, 5 gray (Gy) per day for 6 days, a total dose of 30 Gy. Administration of Ad.Egr-TNF and 30 Gy resulted in complete tumor regression in 71% of xenografts compared with xenografts treated with radiation alone (7.4%, P = 0.006), Ad.Egr-TNF alone (0%, P = 0.012) or Ad.null with 30 Gy (0%, P = 0.002). Combined treatment with Ad.Egr-TNF and 30 Gy significantly reduced mean fractional tumor volumes compared with radiation alone (P = 0.002), Ad.Egr-TNF alone (P = 0.002) and Ad.null plus 30 Gy (P = 0.018). Histopathologic analyses of glioma xenografts treated with Ad.Egr-TNF and radiation revealed tumor vessel thrombosis by day 4 and necrosis by day 7. Thrombosis was not observed in tumors treated with Ad.Egr-TNF alone and was significantly reduced in all other treatment groups. These studies suggest that in the D54 glioma xenograft model, the antitumor effects of combining radiation and Ad.Egr-TNF are mediated, in part, by the destruction of the tumor microvasculature.

Allogeneic bone marrow transplantation for Alexander's disease.

In this case report, we evaluate the efficacy of allogeneic bone marrow transplantation (BMT) in a 7-month-old female with the infantile form of Alexander's disease. Based on research that describes Alexander's disease as a leukodystrophy which may result from an unidentified enzyme deficiency, we attempted marrow transplantation to reverse or arrest the patient's neurological deterioration. Despite an initial return to her pretransplant neurological state, the patient's neurological status deteriorated. Marrow transplantation was not effective in changing her prognosis with Alexander's disease.