CML is associated with the abnormal fusion of a portion of chromosome 21 with a cell growth-promoting enzyme called ABL, which makes the enzyme perpetually active.
Imatinib slows down the spread of cancer by blocking the enzyme's activity.
However, the drug doesn't work in everyone and resistance often develops, most likely because the drug only targets mature cells, leaving self-renewing cancer stem cells behind.
Now, Xiaoyan Jiang and a team of researchers from the British Columbia Cancer Agency in Vancouver and other institutions may have discovered what protects the stem cells from imatinib.
The team found that a protein called AHI-1, which has been found in leukemia cells in the past, is highly expressed in CML stem cells.
When the researchers blocked AHI-1 in cancer cells from imatinib-resistant CML patients, they restored the ability of the drug to kill the cells.
Jiang says the next step is finding a drug that blocks AHI-1, which could potentially be given in combination with imatinib in the future.
The study will appear online on October 20 in the Journal of Experimental Medicine.