New data point to the lasting benefit, for many patients, of a targeted drug that has revolutionized the treatment of a rare digestive-tract cancer.
The findings showed that 26 percent of patients treated with the drug imatinib (Gleevec®) for advanced gastrointestinal stromal tumors (GIST) survived at least eight years after receiving the therapy in a phase III clinical trial. An estimated 22 percent survived at least 10 years.
The findings will be presented at the American Society of Clinical Oncology (ASCO) meeting on June 2, 2014 by Dana-Farber Cancer Institute researchers who led the study with colleagues at cancer centers and hospitals across the United States and Canada.
“This study confirms the long-term benefit of targeted therapy in a subset of patients with life-threatening advanced GIST,” said study leader George Demetri, MD, senior vice president for Experimental Therapeutics at Dana-Farber and director of the Dana-Farber Center for Sarcoma and Bone Oncology. “Our research is focusing on why this subset does so well, and also stresses new ways to address the problems of resistance to targeted therapy with combinations of drugs as well as new therapeutic strategies and novel agents.”
GIST, which is diagnosed in 4,000-5,000 Americans each year, occurs when abnormal cells form in the gastrointestinal tract – the stomach, small intestine, and large intestine. In the vast majority of GISTs, the tumor cells have a mutation in the KIT gene, which causes the cells to divide uncontrollably. Imatinib targets this abnormality.
The new study is based on a long-term follow-up of 695 patients with advanced GIST who participated in a clinical trial of imatinib beginning in 2001. In addition to the survival data, researchers gathered more in-depth information on 179 of these patients. Forty-nine percent of them had been treated only with imatinib for GIST; 39 percent had received other systemic agents. Some of the patients had undergone surgery or received radiation therapy for GIST recurrences.
Researchers are exploring the factors that enable some GIST patients to live with no worsening of their disease for 10 years, and are working to improve treatments for those patients whose GIST cells carry other genetic mutations.
For more information about Dana-Farber research being presented at ASCO, visit www.dana-farber.org/asco.