"Methadone kills sensitive leukaemia cells and also breaks treatment resistance, but without any toxic effects on non-leukemic blood cells," said the study's senior author, Claudia Friesen, Ph.D., of the Institute of Legal Medicine at the University Ulm. "We find this very exciting, because once conventional treatments have failed a patient, which occurs in old and also in young patients, they have no other options."
In this study, Friesen and her colleagues tested methadone in leukaemia cells in laboratory culture because this cancer also expresses the opioid receptor. Theirs is the first study to look at use of the agent in leukaemia, specifically in lymphoblastic leukaemia T-cell lines and human myeloid leukaemia cell lines. They found that methadone was as effective as standard chemotherapies and radiation treatments against non-resistant leukaemia cells, and that non-leukemic peripheral blood lymphocytes survived after methadone treatment.
To their surprise, they found that methadone also effectively killed leukaemia that was resistant to multiple chemotherapies and to radiation. Probing the mechanism of methadone's action, the researchers found that it activates the mitochondrial pathway within leukaemia cells, which activates enzymes called caspases that prompt a cell into apoptosis, also known as programmed cell death. Chemotherapy drugs use the same approach, but methadone activated caspases in sensitive leukaemia cells, and also reversed deficient activation of caspases in resistant leukaemia cells.
Friesen said the research team is beginning to study methadone treatment in animal models of human leukaemia, and she also says that other cancers might be suitable for treatment with the agent.
MEDICA.de; Source: American Association for Cancer Research