Public Release: 

Vion and Yale University awarded SBIR grant to evaluate anticancer effects of armed TAPET® technology in combination with radiation therapy

Vion Pharmaceuticals, Inc.

-- Radiation Enhances TAPET by Increasing Expression of Anticancer Agent --

NEW HAVEN, CT, APRIL 14, 2000 -- Vion Pharmaceuticals, Inc. (NASDAQ NM: VION) today announced they have received a Small Business Innovation and Research (SBIR) grant from the National Institutes of Health (NIH)/National Cancer Institute (NCI) of $100,000. These grants for innovative research are awarded by NIH/NCI competitively; in FY1999 approximately 830 grants were approved out of almost 3,000 applications. This additional funding follows grants totaling $850,000 awarded by the NIH/NCI to Vion to further studies of TAPET®.

TAPET is the designation for a type of Salmonella bacteria that has been modified to permit safe intravenous administration, and in preclinical studies has been shown to accumulate to large numbers within tumors. Injection of TAPET to tumor-bearing animals produces inhibition of tumor growth, and this effect can be enhanced with radiation, resulting in antitumor effects that are greater than those observed with radiation alone or TAPET alone. TAPET can also be modified to carry anticancer agents to the tumor site, thereby increasing its antitumor activity. One of these armed TAPET vectors carries the Colicin E3 toxin (ColE3), which blocks the protein synthesis of cancer cells and kills them. Vion and Yale scientists have shown in preclinical studies that radiation not only improves the antitumor activity of TAPET, but also increases TAPET's production of the ColE3 toxin. The purpose of the new NIH/NCI-funded SBIR grant is to demonstrate the expected improvement in antitumor activity of radiotherapy combined with the TAPET producing the ColE3 toxin. The studies will be conducted in collaboration with Yale University.

"Earlier this month at the 91st Annual Meeting of The American Association for Cancer Research, Vion presented preclinical studies of TAPET armed to express Colicin E3, which demonstrated an increase in antitumor activity compared to TAPET alone in animals," stated Alan Kessman, president and CEO of Vion. "At the same meeting, our collaborators at Yale presented preclinical data showing significantly increased antitumor effects of TAPET when combined with therapeutic doses of radiation therapy. This new NIH/NCI funded SBIR Phase I preclinical study using radiation to induce expression of Colicin E3 by TAPET bacteria is designed to confirm this therapeutic benefit in animals. Combining the localized antitumor effects of TAPET, radiation and Colicin E3 is the kind of 'triple play' treatment that could be useful in treating solid tumors. This grant from the NIH/NCI will provide additional preclinical data to support our ongoing clinical development of TAPET."

TAPET® (Tumor Amplified Protein Expression Therapy), Vion's core platform technology, are highly attenuated bacteria that, in preclinical studies, have demonstrated preferential replication in tumors compared to normal tissues. The bioengineered bacteria have demonstrated an excellent safety profile in preclinical toxicology studies. Preferential replication allows the bacteria to produce and deliver a variety of anticancer therapeutic products at high concentrations to tumors while minimizing toxicity to normal tissues. By bringing the "drug factory" preferentially to the tumor, Vion believes that TAPET may result in a cancer therapy that is more concentrated, more effective and less toxic to normal tissue. Furthermore, the unarmed bacteria by themselves have shown good antitumor activity in animal models. Vion plans to develop the unarmed TAPET alone as an antitumor agent and to develop second-generation products that produce and deliver potent therapeutic anticancer agents.

Vion Pharmaceuticals, Inc. is a biopharmaceutical company engaged in the research, development and commercialization of cancer treatment technologies. Vion's product portfolio consists of TAPET®, a drug delivery platform, and three cancer therapeutics (Promycin®, Triapine® and Sulfonyl Hydrazine Prodrugs). TAPET has been shown in preclinical models to effectively deliver anticancer agents while having a minimal toxic effect on healthy normal tissues. TAPET uses genetically altered strains of Salmonella as a bacterial vector, or vehicle, for delivering cancer-fighting drugs preferentially to solid tumors. TAPET is being evaluated for safety in a Phase I clinical trial at the NCI and at the Cleveland Clinic Foundation. Promycin, which attacks oxygen depleted cancer cells, is currently being evaluated with radiation in a multicenter Phase III clinical trial for the treatment of head and neck cancer. Triapine, which is designed to prevent the replication of tumor cells by blocking a critical step in the synthesis of DNA, is currently being evaluated for its safety in a Phase I clinical trial. Sulfonyl Hydrazine Prodrugs, compounds that are designed to be converted to unique potent, alkylating agents, are currently being evaluated in preclinical studies. For additional information on Vion and its research and product development programs, visit the company's Internet web site at http://www.vionpharm.com.

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