Imatinib Mesylate

Abstract

▴ Imatinib mesylate (imatinib) is an orally administered competitive inhibitor of the tyrosine kinases associated with the KIT protein (stem cell factor receptor), ABL protein and platelet-derived growth factor receptors. The KIT tyrosine kinase is abnormally expressed in gastrointestinal stromal tumour (GIST), a rare neoplasm for which there has been no effective systemic therapy. ▴ In a randomised, nonblind, multicentre study that evaluated imatinib 400 or 600mg once daily in 147 patients with advanced GIST, confirmed partial responses were achieved in 54% of patients overall (median duration of follow-up was 288 days). Stable disease was experienced by 28% of patients and the estimated 1-year survival rate was 88%. ▴ Similar response rates were reported in a smaller, dose-escalation study, in which objective tumour response was a secondary endpoint. ▴ Although nearly all patients with GIST treated with imatinib experienced adverse events, most events were mild or moderate in nature. Severe or serious adverse events occurred in 21 % of patients in the larger study, and included gastrointestinal or tumour haemorrhage.