The trials are taking place at Glasgow Royal Infirmary

This form of blood cancer affects young and old but it is more common in people over 50.

Chemotherapy can help control this type of leukaemia but patients often have to cope with unpleasant side effects.

The only known cure is a bone marrow transplant, for those diagnosed at an early enough age and who can find a suitable donor.

A drug called Glivec, which has been tested elsewhere in the UK and is now being tested at Glasgow Royal Infirmary, could provide new hope.

It works by blocking the action of a key enzyme which appears to trigger the cancerous changes.

Chronic myeloid leukaemia

Genes break and reform all the time, but in people with chronic myeloid leukaemia they break and reform in the wrong way.

The new drug stops that having such a devastating effect.

It differs from conventional chemotherapy in that it can more closely target affected cells, thus reducing the unpleasant and debilitating side effects of treatment.

The trials will be completed by the end of October but doctors have said the results so far are dramatic.

But they stress the drug only puts patients into "remission", meaning doctors could not detect the presence of cancer in patients' bodies.

A bone marrow transplant is still the only complete cure for the disease.

The Anthony Nolan Trust is a bone marrow donor register and charity.

It can be contacted on 0901 8822234