(RxWiki News) Scientists have long observed that the same molecule can have a variety of different functions in the body depending on where it is at that moment.
For example, early drugs used in psychiatry were largely phased out, because the powerful side effects were just too numerous and in many cases dangerous.
Primarily these drugs, traditional antipsychotics, blocked dopamine transmission in the brain, but severe effects could be seen all over the body after using the drug for a few weeks.
"Ask your oncologist about clinical trials."
Laboratory studies by Canadian researchers performed on thioridazine, an older psychiatry drug rarely used today, showed that it successfully killed cancer stem cells in leukemia while leaving healthy stem cells untouched.
While the side effects from thioridazine are notable, they are generally preferable to many types of chemotherapy.
A crucial part of the research was building a unique, fully automated robotic system to test, classify, and identify the molecular actions of dozens of drugs.
This automated system will come in handy in the future for analyzing future molecular structures in far less time.
"Now we can test thousands of compounds, eventually defining a candidate drug that has little effect on normal stem cells but kills the cells that start the tumor," said Mick Bhatia, PhD.
Thioridazine was originally prescribed as a psychiatric drug, is no longer commonly used as there are many side effects, the worst of which include damage to the heart and eyes.
A complex drug with many effects, thioridazine has also been used to treat tuberculosis. But the effects on leukemia seem to be especially profound.
"The unusual aspect of our finding is the way this human-ready drug actually kills cancer stem cells; by changing them into cells that are non-cancerous," stated Bhatia, the study's lead investigator.
Conclusions from the research launched studies of other drugs in the same family as thioridazine, searching for a candidate that retains the power against cancer cells with fewer undesirable effects.
Thioridazine needs to next be tested in clinical trials in patients with post-chemotherapy relapsing acute myeloid leukemia. By targeting the cancer stem cells, Bhatia wants to find out if the drug can put their cancer into remission, and prevent the cancer from coming back. McMaster researchers have already designed plans for these trials.
The study was published in the journal Cell on May 24, 2012.
The research was supported by grants from the Canadian Institute of Health Research (CIHR), the Canadian Cancer Society Research Institute (CCSRI) and several programs sponsored by the province of Ontario.