Analysis of Molecular Cytogenetic Changes in Metastatic Renal Cell Carcinoma in the Setting of Everolimus Treatment: A Pilot Project

BackgroundThe mTOR inhibitors have improved outcomes for patients with metastatic renal cell carcinoma (mRCC) but the duration of benefit is variable. Currently there are no predictive biomarkers for preselecting patients who are more likely to benefit from these agents. We undertook an exploratory translational study evaluating molecular cytogenetic changes in the context of outcomes from treatment with everolimus.Patients and MethodsTen patients with clear cell mRCC treated with everolimus were enrolled. Pretreatment tissue specimens were analyzed for molecular cytogenetic changes using fluorescence in situ hybridization and progression-free survival (PFS) data were obtained. Gene probes chosen for this analysis were: Von Hippel Lindau, fragile histidine triad, fibroblast growth factor receptor (FGFR) 1, FGFR3, PDGFβ, PDGFRβ, epidermal growth factor receptor, and myelocytomatosis viral oncogene.ResultsMedian PFS was 8.75 months. Two patients with the longest PFS (28 months and 23 months) had gain of PDGFβ and PDGFRβ. This was also observed in 3 other patients who had a PFS of 11.5 months, 8 months, and 5.5 months, respectively. Cytogenetic evolution was observed between primary and metastatic specimens.ConclusionPDGFβ and PDGFRβ gene status might be of relevance to everolimus therapy. Further research evaluating the utility of these potential biomarkers is required.