Response to Cancer Vaccine Enhanced by Chemotherapy
By Journal of the National Cancer Institute
Oct 5, 2005, 04:17

A study of a cancer vaccine in mice has found that the vaccine induces a tumor-specific immune response that is enhanced when used with chemotherapy regimens that include 5-fluorouracil (5-FU).

Chemotherapy drugs such as 5-FU inhibit the activity of the enzyme thymidylate synthase (TS), which is necessary for DNA synthesis and cell replication and is often overexpressed in cancer cells. Tumor cells usually respond to the drug exposure by temporarily enhancing the production of this enzyme. Tumor cells can become resistant to 5-FU if they are able to overproduce TS or have mutated enzyme. To determine whether this treatment limitation could be overcome using a peptide vaccine, Pierpaolo Correale, M.D., Ph.D., and Maria Cusi, Ph.D., of Siena University in Italy, and colleagues evaluated mice vaccinated with a peptide (TS/PP) designed to target the enzyme TS.

They report that, in mice vaccinated with TS/PP and subsequently inoculated with TS-expressing lymphoma cells, tumor formation was either delayed or prevented, especially when the mice were also treated with 5-FU. The authors conclude that TS/PP could induce a tumor-specific response in mice and suggest that such a vaccine could have clinical application in humans.

In an editorial, Carmen J. Allegra, M.D., of the Network for Medical Communication Research in North Potomac, Md., and Richard W. Childs, M.D., of the National Heart, Lung, and Blood Institute, note that this vaccine approach, if translatable into the management of human cancer, would be remarkable but caution that it requires additional preclinical study of potential barriers to clinical use in patients.

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