News Release

VION Awarded SBIR grant to advance its armed Tapet® technology

Grant and Award Announcement

Vion Pharmaceuticals, Inc.

-- Grant Supports the Preclinical Development of the Company's Armed TAPET Vector Technology to Battle Cancer --

NEW HAVEN, CT, JANUARY 18, 2000 -- Vion Pharmaceuticals, Inc. (NASDAQ NM: VION) today announced it has received a two-year, Small Business Innovation and Research (SBIR) grant from the National Institutes of Health (NIH)/National Cancer Institute (NCI) of $750,000. Vion is investigating the use of bacterial vectors as a safe and efficacious anti-cancer treatment, and the objective of this study is to advance the company's preclinical efforts of its armed (bioengineered) TAPET® technology to express certain potent anti-cancer agents. This additional funding follows an initial grant of $100,000 awarded by the NIH/NCI to Vion in April 1998 to further studies of TAPET for the potential treatment of cancer. TAPET uses genetically altered Salmonella to colonize, multiply preferentially in solid tumors and produce cancer-fighting drugs within the tumors, as shown in preclinical studies.

The grant will be applied to enhance the anti-tumor efficacy of VNP20009, the company's first generation TAPET bacterial vector, by arming a variety of vectors to express high levels of enzymes that activate prodrugs (nontoxic compounds that can be converted into active anticancer agents) and cytokines (small proteins that have specific effects on the immune system) directly at the tumor site.

"The purpose of this grant is to engineer and to evaluate the cancer-fighting ability of certain armed TAPET vectors," stated Ivan King, Ph.D., vice president of research at Vion. "The aim of the study is four fold: To use TAPET to deliver certain prodrug-activating enzymes, individually and in combination, to increase the concentration of anticancer agents in the tumor; To use TAPET to secrete cytokines at the tumor site to elicit an antitumor response by activating the immune system; To determine optimal dose levels and inoculation frequency for tumor accumulation and intratumoral gene expression of these armed TAPET vectors; To evaluate the ability of specific mechanisms) to enhance TAPET's release of certain cytokines."

Alan Kessman, president and CEO of Vion, said, "The additional funding from this generous grant will help broaden our TAPET® program and greatly assist us in evaluating how we can improve TAPET's antitumor capabilities when armed to express specific anti-cancer agents. We begin this new millennium with progress on many fronts including continued enrollment at the Cleveland Clinic Foundation for a Phase I human safety trial of TAPET, as well as expanded preclinical activities on our own and in collaboration with others, such as our new agreement with AstraZeneca. We are encouraged by the increased interest in the potentially broad clinical utility of our unique technology in the fight against this deadly disease."

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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 anti-cancer 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 anti-tumor activity in animal models. Vion plans to develop the unarmed TAPET alone as an anti-tumor agent and to develop second-generation products that produce and deliver potent therapeutic anti-cancer 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. 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.

Statements included in this press release, which are not historical in nature, are forward-looking statements made pursuant to the safe-harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements regarding the company's future business prospects, plans, objectives, expectations and intentions are subject to certain risks, uncertainties and other factors that could cause actual results to differ materially from those projected or suggested in the forward-looking statements, including, but not limited to those contained in Vion Pharmaceutical's Registration Statement filed on Form S-3/A (file no. 333-79939). This press release shall not constitute an offer to sell or the solicitation of an offer to buy the common stock nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.


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