TAPET® : Tumor Amplified Protein Expression Therapy, is a modified Salmonella vector used to deliver anticancer agents directly to tumors.

Q. What is TAPET® and how does it work?

A: TAPET® is live attenuated Salmonella bacteria that has been shown in animal studies to selectively accumulate in tumor tissue over normal tissue. Vion seeks to employ TAPET® technologies as a means of delivering anticancer therapy directly to tumors.

Q. Why and how does TAPET® accumulate in tumors?

A: The TAPET® bacteria move throughout the body but are generally destroyed by the immune system as they move through normal body tissue. Once they penetrate a tumor, however, tumor-produced substances are thought to inhibit the immune system, thereby permitting replication and accumulation of the bacteria. Tumors also have areas of rapid cell turnover and low-oxygen tension, which provide nutrients and favorable growth conditions for the bacteria. TAPET® bacteria will replicate in the tumor by doubling every 30 to 40 minutes, growing to about 100 million to 1 billion bacteria per gram of tumor tissue. This can result in 1000-fold or more greater concentration of bacteria in tumors compared to normal tissues.

Q. How will TAPET® treat cancer?

A: Conventional cancer treatments are limited by the amount of drug that reaches the tumor, and by the toxicities of the drug, since normal tissues are exposed to similar or higher concentrations of drug than tumor tissue. Therefore, cancer drugs must be given intermittently to allow normal tissues to recover, but duringtreatment tumor cells can also thus recover from the effects of the cancer drug. The accumulation of TAPET® bacteria in tumor suggests that any cancer fighting agent produced by the bacteria will also be at much higher concentrations in the tumor compared to normal tissue. Furthermore, because the bacteria remain in the tumor for prolonged periods, the delivery of the cancer-fighting agent is continuous.

Vion scientists have also engineered the bacteria to produce cancer-fighting substances. These armed bacteria have already been shown to produce large amounts of a cancer-fighting substance in animal tumors.

Q. What is the status of the TAPET® product development?

A: First generation TAPET® vectors were studied in several Phase 1 trials. Second generation TAPET® vectors were evaluated in veterinary clinical studies in dogs. Vion is now seeking a development partner to assist with continued development of its TAPET® technology.