Efficacy and Safety Study of Dasatinib in Patients With Chronic Myeloid Leukemia

Primary Objective:

1. To assess the efficacy of Dasatinib therapy in chronic and accelerated phase BCR-ABL (+) (Ph + and Ph -) CML patients that undergo molecular, cytogenetic or haematological relapse following SCT.

Secondary Objective(s):

1. To assess the impact of Dasatinib therapy on patient survival after relapse post-SCT and the incidence of any subsequent need for 'rescue' DLI.
2. To assess the safety of Dasatinib in this clinical context using this specific dose regimen

Chronic myeloid leukaemia (CML) is a form of cancer that starts in cells within the bone marrow called haematopoietic stem cells. Stem cells are immature cells which can divide many times and eventually produce all the lymphocytes and myeloid cells present in the blood. They are produced in the bone marrow - the spongy tissue found in large bones, including the pelvis, sternum, limb bones and the ribs.

Leukaemia is a cancer of the white blood cells. In CML, too many myeloid cells (one of the main types of white blood cells which defend the body against infectious diseases) are produced. The myeloid cells are released into the blood when they are immature and unable to work properly. These immature white blood cells are known as blasts.

The immature cells fill up the bone marrow and prevent it from making blood cells properly. As the leukaemia cells do not mature, they can't do the work of normal white blood cells, which leads to an increased risk of infection. Because the bone marrow is overcrowded with immature white cells it also can't make enough healthy red cells and platelets.

CML usually develops very slowly, which is why it is called 'chronic' myeloid leukaemia.

The aim of this study is to assess the efficacy (indicates the capacity for beneficial change or therapeutic effect) of a leukaemia treatment called dasatinib (sprycel) in patients with relapsed Chronic Myeloid Leukaemia (CML) following a Stem Cell Transplant (SCT) and who are not benefiting from other treatment, such as imatinib therapy.

A relapse is when an illness that has seemed to be getting better, or to have been cured, comes back or gets worse again.

Dasatinib works by blocking (inhibiting) signals within cancer cells that cause the cell to grow and divide.

The growth of cells in our bodies is controlled by signals that switch on and off within the cells. When the signals for growth are switched on the cells are triggered to grow and multiply. People with CML have an abnormal signaling protein inside their leukaemia cells. This abnormal protein sends out grow-and-divide signals to the cells at all times and never switches off.

Dasatinib finds the faulty protein and locks onto it. This prevents the protein from stimulating the cells to grow. Dasatinib is known as a signal transduction inhibitor, because it blocks the 'grow' signal. The chemical it blocks is called tyrosine kinase, so dasatinib is also known as a tyrosine kinase inhibitor.