Molecular biomarkers and imatinib efficacy in metastatic gastrointestinal stromal tumors (an experience of the Russian Cancer Research Center)

Abstract

21500 Background: The aim of the study was an evaluation of efficacy of imatinib as first-line therapy in patients with unresectable or metastatic gastrointestinal stromal tumor. We also evaluated an expression of molecular biomarkers of apoptosis, angiogenesis and proliferation in primary tumors to define new factors predicting the efficacy of treatment. Methods: 51 patients (pts) with CD117 expression in tumor were included into the study. Mean age was 60 years (range 20–76). Most of pts had hepatic metastases and/or peritoneal metastases. Median duration of imatinib treatment was 13.5 months (range 1–67+). Expression of molecular markers (Ki67, p53, Bcl-2, Bax, VEGF, PDGFR beta) was evaluated by immunohistochemistry on tumor paraffin blocks. Results: The efficacy of treatment was evaluated in 47 of 51 pts. Imatinib was effective in 93.6% cases (26 pts achieved partial remission, 1 - complete response, 17 - prolong stabilization). Response duration for complete and partial remission was (from starting o...