Abstract
Sunitinib is an anti-angiogenic receptor tyrosine kinase inhibitor used to treat advanced metastatic renal cell carcinoma and other types of cancer. Sutent is effective in only approximately 70% of clear cell renal cell carcinoma (CCRCC) patients, has significant adverse side effects and no method is available to predict which patients will not respond. Our purpose was to explore the possibility of introducing an effective prediction method based on a marker of the tumour vasculature, the follicle stimulating hormone receptor (FSHR). Fifty patients diagnosed with advanced metastatic CCRCC have been subjected to surgery for removal of the primary tumour and were subsequently treated with sunitinib. After three months of therapy the patients were categorized as 'responsive', 'stable' or 'non-responsive' based on the RECIST guidelines. The blood vessel density and the percentage of FSHR-positive vessels were determined by immunofluorescence on sections from the primary tumours removed by surgery, prior to the sunitinib treatment. The percentage of FSHR-stained vessels was on average fivefold higher for the patients who responded to the treatment in comparison with the stable group and almost eightfold higher than in the non-responsive group. The percentage allowed the detection of responders with 87-100% sensitivity and specificity. No significant differences were detected in the total density of vessels among the three groups. The data suggest that FSHR expression levels in the blood vessels of CCRCC primary tumours can be used to predict, with high sensitivity and specificity, the patients who will respond to sunitinib therapy.