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Phase II evaluation of imatinib mesylate in the treatment of recurrent or persistent epithelial ovarian or primary peritoneal carcinoma: a Gynecologic Oncology Group Study.

PURPOSE
This phase II trial assessed the activity and tolerability of an oral dose of imatinib mesylate 400 mg twice daily in patients with recurrent or persistent epithelial ovarian or primary peritoneal carcinoma. The association between the expression of certain markers and clinical outcome was investigated.


PATIENTS AND METHODS
Primary measure of clinical efficacy was progression-free survival (PFS) at 6 months. Mutational analysis of KIT, immunohistochemistry (IHC) and enzyme-linked immunosorbent assay for markers (KIT, platelet-derived growth factor [PDGF] receptor [-R], AKT2, phosphorylated AKT [p-AKT], stem cell factor [SCF], and PDGF) were performed.


RESULTS
Fifty-six eligible patients were evaluated. Nine patients were progression free for at least 6 months including one complete responder. The median PFS and survival were 2 and 16 months, respectively. The most common grade 3 and 4 toxicities were neutropenia, GI, dermatologic effects, pain, and electrolyte disturbances. At least one target of imatinib (KIT, PDGFR-alpha, or PDGFR-beta) was expressed in all tumors, and most tumors expressed all three receptors. Higher expression of p-AKT and PDGFR-beta were associated with shorter PFS, and higher IHC scores (% immunopositive cells x staining intensity) of SCF and p-AKT were associated with decreased overall survival. No sequence mutations were detected in the KIT gene. Higher pretreatment plasma concentrations of PDGF-AB, PDGF-BB, and vascular endothelial growth factor (VEGF) were individually associated with shorter PFS and survival.


CONCLUSION
Imatinib mesylate was well tolerated but had minimal single-agent activity in patients with recurrent ovarian or primary peritoneal carcinoma. No marker was identified that would predict activity of imatinib; however, tumor p-AKT and plasma VEGF levels were associated with poor outcome.