Imatinib mesylate (Glivec) as a treatment for gastrointestinal stromal tumor (Gist) - Long term follow-up

Background: Gastrointestinal stromal tumor (GIST) is a rare gastrointestinal tumor. It is known to be resistant to radiotherapy and chemotherapy. The administration of imatinib mesylate, a tyrosine kinase inhibitor, resulted in a dramatic response and improved survival in patients with GIST. This study examined the long term response and side effects of imatinib treatment in Israeli patients with GIST. Patients and Methods: The study followed-up on 25 patients from various hospitals in Israel treated between the years 2001 and 2006. The mean follow-up time was 36.3 months (17-63 months). Results: One patient achieved complete response, 13 patients (52%) achieved partial response, 9 patients (35%) achieved stable disease, and 2 patients did not have measurable disease. The median survival was not yet reached. Twelve patients (48%) had a decrease in the attenuation of the tumor into a cystic appearance. Eleven patients (44%) developed late resistance to the treatment (after 7-54 months). The median time to progression was not yet reached. The adverse events were mostly mild. Severe adverse events (grade 3-4 Common Toxicity Criteria (CTC)) occurred in 24% of the patients. There was no advantage regarding survival or time to progression for the patients who had partial response compared to those patients who had stable disease (P=0.39 and P=0.71 respectively). Conclusions: Imatinib results in a dramatic response in patients with GIST, and is well tolerated. The introduction of new drugs such as sunitinib which is now in an advanced phase of clinical study, may provide additional solutions in the treatment of GIST.