A NEW drug that targets tumour stem cells could help overcome cancer resistance, researchers have claimed.
Existing cancer drugs are often effective against mature cells, but allow a few resistant cancer stem cells to escape.
These go on to produce resistant “daughter” cells that do not respond to therapy, allowing the cancer to grow and spread.
The new drug, called a “notch inhibitor”, stops the stem cells becoming resistant.
In a pilot study, 20 women with breast cancer were given the experimental notch-inhibitor MK-0752. Scientists found it switched off key genes that would have kept the stem cells resistant to conventional drugs.
“Our results suggest a potential role that notch inhibitors could play in optimising existing therapies and in overcoming resistance to cancer drugs,” said lead researcher Dr Kathy Albain, from Loyola University Medical Center in Maywood, US.
The findings were presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium in Texas, US.
The drug targets “notch protein” which is present on the surface of cancer stem cells and promotes tumour growth and survival.
Interaction between the protein and other cell molecules activates genes in stem cells that trigger resistance.
All the women taking part in the trial had early-stage hormone-sensitive breast cancer fuelled by oestrogen.
Prior to surgery, the patients received one of two commonly used drugs, tamoxifen or letrozole, which block oestrogen stimulation of cancer cells. In addition, they were treated with MK-0752. After treatment, biopsy tissue samples were removed from the women’s tumours for analysis. #
Tests revealed that MK-0752 was working as intended, with minimal side effects.
The scientists are now planning to conduct a larger scale clinical trial in which breast cancer patients given oestrogen-blocking drugs would be compared with another group also treated with a notch inhibitor.