That finding appears in the March 27 issue of The New England Journal of Medicine.
The study included 11 people with hypereosinophilic syndrome (HES), a blood disorder that nearly always kills the patient.
HES is caused by overproliferation of white blood cells called eosinophils. It leads to major organ damage and eventual failure of the heart or lungs.
This study found that nine of the 11 people had extraordinary and continuing responses to treatment with Gleevec.
The researchers, from Howard Hughes Medical Institute and the Dana-Farber Cancer Institute, wanted to find a molecular explanation for Gleevec's success in treating these people.
Genetic analysis revealed that a small deletion of DNA in a region between two known genes, FIP1L1 and PDGFR alpha, produced a tyrosine kinase that's turned on in the absence of a normal activation signal.
The researchers then found that Gleevec blocked the activity of the wayward tyrosine kinase.
The finding of this mechanism may encourage scientists to take a closer look at whether this newly discovered mechanism may cause other forms of cancer.
Here's where you can learn more about Gleevec.