New Drug Therapy Attacks Cancers

Main Category: Cancer / Oncology
Article Date: 01 Jul 2008 - 5:00 PDT

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A new targeted drug therapy developed at The Institute of Cancer Research is showing positive results in killing tumour cells of some common cancers in the laboratory, according to a study published in Clinical Cancer Research today (July 1).

The pre-clinical study, funded by Cancer Research UK, revealed the new drug therapy had the ability to kill melanoma, breast and colon carcinoma models.

Lead investigator, Professor Caroline Springer said: "In the case of breast cancer models, the drug therapy proved effective in significantly reducing tumour size in an aggressive type of breast cancer."

Researchers used modified Salmonella* bacteria that target and survive in tumours. When combined with a prodrug, the therapy results in the death of the tumour cells.

"The modified Salmonella produce a foreign enzyme in the tumour. Once the enzyme has accumulated at the tumour site, a non-toxic prodrug is administered. The foreign enzyme converts the prodrug to a drug that is toxic, thereby killing the cancer cells," Prof. Springer said.

"It's the first time this therapy has proved successful in killing melanoma, breast and bowel cancer models."

The published results show that three different prodrugs, designed and synthesised by researchers at The Institute of Cancer Research, are all effective in reducing the size of the melanoma, breast and colon carcinoma tumour models.

Summary of results:

- In the breast cancer model, the most effective therapy reduced the tumour volume significanly using any of the three prodrugs.

- In the colorectal carcinoma model, there was a significant reduction in tumour volume using one prodrug.

- In the melanoma model, there was a significant reduction in tumour volume using two prodrugs.

Professor Springer said whilst the results showed great potential, plans for human trials were on hold as further modifications to the Salmonella vector needed to be undertaken to remove any potential toxicity in humans.

Dr Lesley Walker, director of cancer information at Cancer Research UK: "This is a very positive step forward for scientists developing new enzyme-prodrug treatments. One of the major challenges in this field is to find effective ways to successfully deliver the activating enzyme to the cancer cells. By harnessing the power of bacteria that carry the enzyme directly to the tumour, these researchers have demonstrated an effective way to achieve this."

*This form of Salmonella, VNP20009 was developed by Vion Pharmaceuticals Inc (New Haven, USA). It was modified to remove the msbB gene that leads to toxicity, and the purI gene to foster targeting to tumours.

About The Institute of Cancer Resesarch

- The Institute of Cancer Research is Europe's leading cancer research centre with expert scientists working on cutting edge research. It was founded in 1909 to carry out research into the causes of cancer and to develop new strategies for its prevention, diagnosis, treatment and care. For more information visit www.icr.ac.uk.

- The Institute is a charity that relies on voluntary income. The Institute is one of the world's most cost-effective major cancer research organisations with over 90p in every £ directly supporting research.

The Institute of Cancer Research