Vion's TAPET® administered to first patients in Phase I human intratumoral safety trial at the Cleveland Clinic ...( NEW HAVEN CONN. DECEMBER 8 1999 --...)

NEW HAVEN, CONN., DECEMBER 8, 1999 -- VION PHARMACEUTICALS, INC. (NASDAQ NM: VION) today announced that VNP20009, the company's first generation TAPET® bacterial vector, has been administered to the first patients enrolled into Vion's Phase I intratumoral trial, which is being conducted at The Cleveland Clinic Foundation. The patients were initially monitored in the hospital and subsequently discharged. Potential safety and efficacy will continue to be monitored according to the protocol. The Phase I study is designed to evaluate the safety, potential efficacy and optimum biological dose of an intratumoral administration for patients with either cutaneous or subcutaneous solid tumors. Patients will be evaluated for the accumulation of VNP20009 in the tumor and non-injected lesions. Patient accrual continues for this trial, which may involve up to 20-30 patients.

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 commerci
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Contact: Sue Yeoh
syeoh@cpronline.com
201-641-2408 x43
Vion Pharmaceuticals, Inc.
8-Dec-1999