Expression of drug targets in primary and matched metastatic renal cell carcinoma tumors

BACKGROUND

Targeted therapies in renal cell carcinoma can have different effects on primary and metastatic tumors. To pave the way for predictive biomarker development, we assessed differences in expression of targets of currently approved drugs in matched primary and metastatic specimens from 34 patients.

METHODS

Four cores from each site were embedded in tissue microarray blocks. Expression of B-Raf, C-Raf, cKIT, FGF-R1, HIF-2α, mTOR, PDGF-Rβ, VEGF-R1, VEGF-R2, VEGF-R3, VEGF, VEGF-B, VEGF-C, VEGF-D, MEK1, and ERK1/2 was studied using a quantitative immunofluorescence method.

RESULTS

No significant differences were observed in global expression levels in primary and metastatic renal cell carcinoma tumors, with the exception of MEK, which had higher expression in metastatic than primary specimens. Similarly, more ki67 positive cells were seen in metastatic specimens. Correlations between marker expression in primary and metastatic specimens were variable, with the lowest correlation seen for FGF-R1 and VEGF-D. There were no significant differences in the degree of heterogeneity in primary versus metastatic tumors.

CONCLUSIONS

Expression of most of the studied markers was similar in primary and metastatic renal cell carcinoma tumors, suggesting that predictive biomarker testing for these markers can be conducted on either the primary or metastatic tumors for most markers.

Novelties of treatment in advanced renal-cell cancer

Therapeutic options in advanced renal-cell cancer have expanded through better understanding of molecular patho­logy and development of novel targeted therapeutics. Vascular endothelial growth factor, the key ligand of angioge­nesis, has a major role in the progression of vascularized kidney tumors and this is the target molecule of modern medications. The three types of the mechanism of action of current therapies are: monoclonal antibodies blocking directly vascular endothelial growth factor ligand (bevacizumab), tyrosine-kinase inhibitors blocking vascular endothelial growth factor receptors (sorafenib, sunitinib, pazopanib) and inhibitors of the intracellular mTOR-kinase (temsirolimus, everolimus). Based on randomized studies, sunitinib, pazopanib or interferon-α-bevacizumab combination should be the first-line therapy in patients with good/moderate prognosis, while temsirolimus is recommended in those with poor prognosis. Following an ineffective cytokine therapy sorafenib or pazopanib are the se­cond-line treatment. In case of tyrosine-kinase inhibitor inefficacy, current evidence favors everolimus. Patient outcome can further be improved by the involvement of more modern and effective target products. Orv. Hetil., 2011, 152, 655–662.