Aims: Tyrosine kinases are promising targets for personalized medicine, and new drugs are currently in phase 2 and phase 3 clinical trials. However, expression analysis of tyrosine kinases as predictive biomarkers is still not a standard approach. Furthermore, only limited studies have investigated the expression of tyrosine kinase receptors on the protein level. In this study, we analysed a well-characterised group of soft tissue sarcomas for different tyrosine kinase receptors and correlated the results with clinicopathological parameters, including survival.
Methods: 275 soft tissue sarcomas of our Sarcoma center at the Ludwig-Maximilians-University (LMU) were reinvestigated and categorized according to the current WHO classification system. The tumor collective included undifferentiated pleomorphic sarcomas (n=81), leiomyosarcomas (n=50), synovial sarcomas (n=27), liposarcomas (n=51), angiosarcomas (n=43) and other soft tissue sarcomas (n=23).
Results: On protein levels, high expression of VEGFR1 was detected immunohistochemically in 61%, VEGFR2 (KDR) in 11%, VEGFR3 in 64%, PDGFRA in 42% and PDGFRB in 73%. High expression of VEGFR1-3 and PDGFRB was significantly correlated with higher grading (G2 vs G3, p<0.05), and high VEGFR2 was significantly correlated with decreased patients' survival (p<0.001).
Conclusions: Tyrosine kinase receptors showed a distinct expression pattern in soft tissue sarcomas. High expression of VEGFR2 (KDR) is significantly associated with decreased patients' survival. High VEGFR 1-3 and PDGFRB are significantly correlated with higher tumor grading. Protein signatures might be evaluated before targeted therapy to give a rationale for an eligible personalized therapy.
Keywords: Immunohistochemistry; PDGFR; Sarcoma; Survival; VEGFR.
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