VA Researchers Show How Imatinib Improves Prognosis for Hard-to-Treat Cancer

By Annette M. Boyle

PORTLAND, OR — Not long ago, less than a third of chronic myeloid leukemia (CML) patients survived five years and gastrointestinal stromal tumor (GIST) patients had an even shorter life expectancy, according to the National Cancer Institute. Now significant numbers of patients with these cancers live for another 10 years after diagnosis.

What changed? Several recent studies, including some involving VA research, highlight the improved survival rates in multiple cancers since the development of imatinib kicked off the race to develop personalized, non-toxic therapies. Imatinib, a selective tyrosine kinase inhibitor that is administered orally, dramatically improved survival rates for both gastrointestinal stromal tumor (GIST) and (CML).

Before imatinib, “patients with advanced GISTs faced a life expectancy of 18 months,” said Michael Heinrich, MD, a researcher with Portland Veterans Affairs Health Care System and professor of medicine at the Oregon Health & Science University School of Medicine. “Now we’ve learned that some might live a decade or longer.”

GISTs are soft-tissue sarcomas that can occur anywhere in the gastrointestinal tract. About 6,000 new cases are diagnosed annually nationwide.

The long-term study appeared in the February issue of JAMA Oncology. Researchers followed 695 adults with advanced, inoperable gastrointestinal stromal tumors who were enrolled in a phase III study that started in 2000. A previous report on the study, published in 2008, confirmed imatinib’s effectiveness and recommended treatment with 400 mg daily dose. The initial study had randomized patients to receive either 400 mg per day or 800 mg daily, which was continued until progression or unacceptable toxic effects occurred.1

Of the initial participants, 189 survived for at least eight years and researchers estimated 10-year survival rates of 23% and progression-free survival rates of 7%. About equal numbers of the long-term survivors received 400 mg per day (95) or 800 mg per day (94) of imatinib.

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