A new approach in treating acute myeloid leukaemia; directing radiation into the cancer cell

Acute myeloid leukaemias (AML) account for 40% of all adult leukaemias, with the number of patients being diagnosed rapidly, especially in the elderly. Although current treatments, such as chemotherapy, cures 60-80% of AML patients, in most cases the cancer comes back. Once the cancer has returned, it is a lot more difficult to treat, with the cure rate after patients have received chemotherapy to treat the returning cancer, dropping dramatically to only 10-15%. The growing numbers of AML patients and the ineffectiveness of current treatment, means there is a desperate need for an alternative, more effective therapy for AML patients. One such therapy is radioimmunotherapy (RIT), which is a powerful new approach in selectively targeting and killing cancer cells, yet avoiding normal cells. Research involving RIT for patients with returning AML, have targeted the CD33 protein, present on the surface of most blood cells.
CD33 is specifically targeted by the antibody M195, which was attached to a variety of radioactive molecules that all released different types of radiation. Results showing an excellent cancer killing ability, however, most also damaged normal tissue in the direct vicinity of the tumour, due the relatively long distances travelled by the type of radiation used. Although this normal tissue damage was no where near the levels of damage caused by chemotherapy, it was still far from ideal. In an attempt to reduce this normal cell damage a different radioactive molecule; releasing radiation that could only travel very short distances, was attached to M195. As the radiation only travels short distances, it is only harmful to a cell if it is actually inside it. A special technique was used to direct this radioactive antibody into the cancer cell; once inside the radiation caused serious DNA damage, killing the cell. The surrounding cells were left completely unharmed.