New treatment for leukaemia

A NEW treatment developed at Hammersmith Hospital and the Imperial College School of Medicine, both in London, may also prove valuable in treating solid tumours such as breast and lung cancer. The United Kingdom treatment uses T-cells - human white blood cells that are part of the immune system that defends us against disease - which have been trained to destroy leukaemic cells without harming normal healthy tissue.

For most of the 18,000 people who are diagnosed every year in the U.K. as suffering from leukaemia, there are two treatment options. One is chemotherapy that uses drugs to kill cancerous cells. The other treatment sometimes available is bone marrow transplantation.

The patient's diseased bone marrow is killed with chemicals or radiation and replaced by healthy bone marrow taken from a well- matched donor.

The treatment was developed by Dr. Hans Stauss, of the Department of Immunology in the Hammersmith Hospital, London, Dr. Stauss had identified a gene, known as WTI, which is over-expressed in cells which have become malignant and are causing leukaemia.

This over-expression makes it possible to condition T-cells to recognise leukaemic cells and to destroy them selectively.

Different types of stem cells replenish different parts of the body. The stem cells which produce new, white blood cells are found in the marrow of big bones. Normal stem cells divide only when new cells are required. But leukaemic stem cells, like other cancer cells, divide continually in an uncontrolled fashion.

Until now, no way has been found to destroy leukaemic stem cells that does not have serious side-effects on normal stem cells and other normal fast-dividing cells in the body.

Chemotheraphy attacks all fast-dividing cells, not just cancer cells. The alternative treatment also has severe limitations because suitable donors for bone-marrow transplants are frequently not available according to a report in London Press Service.

The history of cancer research is littered with unsuccessful attempts to find some target on the surfaces of cancer cells that is not present on normal cells and which could be used to attack cancer cells without damaging normal cells.

In this case Stauss has found that, although the protein made by the WTI gene is sometimes present on normal cells, it is present on leukaemic cells in considerably higher concentrations.

He has shown that human T-cells grown in laboratory cultures can be conditioned to recognise and destroy leukaemic cells carrying such higher concentrations of the WTI protein, while ignoring normal cells with normal concentrations of the protein.

Laboratory tests have shown that treatment with conditioned T- cells is effective in reducing the numbers of leukaemic stem cells without affecting normal cells.The next step will be phase one trials in human patients that are now being organised and are expected to begin in the next few months.

Phase one trials are designed to discover if treatment which have shown promise in laboratory tests live up to their promise in patients and, if so, how they may best be used in human therapy.

A potential problem with this treatment is that the foreign T- cells used are bound to be recognised as ``strangers'' and attacked and rejected by the patient's immune system.

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Section  : Science & Tech
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