PORTLAND, Ore. -- Patients with gastrointestinal stromal tumors (GIST) who have a particular genetic mutation are more likely to respond to Gleevec (imatinib) than those without the mutation, according to OHSU study results showcased at the 2005 annual meeting of the American Society of Clinical Oncology (ASCO). The results confirm previous observations and provide a foundation for molecular testing that can predict who will best respond to treatment with Gleevec.
"Increasingly, there will be more drugs like Gleevec that are very specific in their action, and patients' responses to them will be dictated by their tumor biology," said Michael C. Heinrich, M.D., principal investigator of the study. "Performing molecular tests on patients' tumors will be useful for doctors in determining how patients should be treated."
Heinrich is a professor of medicine (hematology/medical oncology) in the OHSU School of Medicine and the Portland Veteran Affairs Medical Center (PVAMC) and a member of the OHSU Cancer Institute.
Gastrointestinal stromal tumors, which occur in the stomach and intestines, are diagnosed in about 5,000 Americans annually. Surgery is the treatment of choice for localized tumors, but in many patients the tumor recurs and spreads elsewhere, particularly to the liver. Without Gleevec, at this metastatic stage the disease is rapidly fatal because chemotherapy, radiation and surgery are ineffective in advanced cases.
Gleevec works by inhibiting a protein called KIT, which is abnormally expressed in GIST and fuels tumor growth by signaling cancer cells to keep growing. The majority of GIST patients have dramatic clinical improvement in their disease (tumor shrinkage) after beginning treatment with Gleevec. However, more than half of patients develop resistance to the therapy and experience disease progression after about two years.
In a previous study, Heinrich and colleagues identified differences in the clinPage: 1 2 3 Related medicine news :1
Contact: Rachel MacKnight
Oregon Health & Science University
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