SCIENTIFIC ADVANCES

Imatinib Mesylate Decreases Cancer Recurrence for Patients with Primary Gastrointestinal Stromal Tumor

Preliminary results from a large, randomized, placebo-controlled clinical trial for patients with primary gastrointestinal stromal tumor (GIST) demonstrated that patients who received imatinib mesylate after complete removal of their tumor were significantly less likely to have a recurrence of their cancer compared to those who did not receive imatinib. This intergroup clinical trial, Z9001, was led by the American College of Surgeons Oncology Group.

Over 600 patients with primary tumors 3 cm or larger that had been completely removed with surgery were enrolled in the trial between June 2002 and April 2007. Patients were randomized to one of two treatment arms. One patient group received imatinib at a dose of 400 milligrams per day for 1 year. The second group received placebo for 1 year. Neither the patients nor their physicians knew which treatment the patients were receiving. Patients who developed a recurrence of their cancer while on study therapy were unblinded to their treatment assignment. Those patients who had been on placebo subsequently received imatinib and those who had been on imatinib continued their imatinib therapy, but at a higher dose. Researchers found that approximately 97 percent of patients in the study who received one year of imatinib after surgery did not have a recurrence of their cancer compared to 83 percent of patients who received one year of placebo. In addition, imatinib therapy was well tolerated by most patients enrolled in the study. The difference in recurrence-free survival was most pronounced in patients with tumors between 6 to 10 cm and tumors greater than 10 cm. There was no difference in overall survival for patients on the two treatment arms.

DeMatteo R, Owzar K, Maki R, Pisters P, Blackstein M, Antonescu C, Blanke C, Demetri G, von Mehren M, Ballman K; American College of Surgeons Oncology Group (ACOSOG) Intergroup Adjuvant GIST Study Team. Adjuvant imatinib mesylate increases recurrence free survival (RFS) in patients with completely resected localized primary gastrointestinal stromal tumor (GIST): North American Intergroup Phase III trial ACOSOG Z9001. Presented at: 43rd American Society of Clinical Oncology (ASCO) Annual Meeting. June 2–5, 2007. Chicago, IL. Abstract #10079.