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Refining Treatment for Gastrointestinal Stromal Tumors

Name of the Trial

Phase III Randomized Study of Imatinib Mesylate With Versus Without Bevacizumab in Patients With Metastatic or Unresectable Gastrointestinal Stromal Tumor (SWOG-S0502). See the protocol summary.

Principal Investigators

Dr. Charles Blanke and Dr. Margaret von Mehren, Southwest Oncology Group; Dr. George Demetri, Cancer and Leukemia Group B; Dr. Vivien Bramwell, NCIC-Clinical Trials Group.

Dr. Charles Blanke

Dr. Charles Blanke
Principal Investigator

Why This Trial Is Important

Gastrointestinal stromal tumor (GIST) is a type of sarcoma that usually forms in the stomach or small intestine, but it can arise anywhere in the gastrointestinal tract. About 5,000 new cases of GIST are diagnosed in the U.S. each year.

The FDA's approval of the drug imatinib (Gleevec) for the treatment of GIST in 2002 dramatically improved the outlook for patients with tumors that cannot be surgically removed (unresectable) or that have spread (metastatic). In previous clinical trials, imatinib helped block tumor growth in more than 80 percent of patients with advanced GIST. Unfortunately, however, patients frequently develop resistance to imatinib after an average of about 24 months.

Recent studies suggest that blocking the growth of new blood vessels (angiogenesis) may help prolong the time during which GISTs don't grow and thus prolong progression-free survival. The biological agent bevacizumab (Avastin) blocks the activity of a protein called VEGF that promotes angiogenesis. High levels of VEGF in GIST usually indicate that the cancer is more aggressive.

In this randomized trial, patients with unresectable or metastatic GIST will receive imatinib therapy with or without the addition of bevacizumab. Researchers hope that the combination of imatinib and bevacizumab will extend progression-free survival by 6 or more months.

"Imatinib works extremely well for most patients with advanced GIST, but we're trying to make it better by extending the time to imatinib resistance," said Dr. Blanke. "Additionally, we're trying to modify the imaging techniques we use to see whether the tumors are responding so that we can better determine the success of treatment for patients with GIST."

For More Information

See the lists of entry criteria and trial contact information or call the NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). The toll-free call is confidential.

This trial is eligible for special Medicare coverage. See .


  • Posted: August 5, 2008