Expression of PSMA in tumor neovasculature of high grade sarcomas including synovial sarcoma, rhabdomyosarcoma, undifferentiated sarcoma and MPNST

// Birthe Heitkotter 1 , Marcel Trautmann 1 , Inga Grunewald 1 , Martin Bogemann 2 , Kambiz Rahbar 3 , Heidrun Gevensleben 4 , Eva Wardelmann 1 , Wolfgang Hartmann 1 , Konrad Steinestel 1 and Sebastian Huss 1 1 Gerhard Domagk Institute of Pathology, University Hospital Munster, University of Munster, Germany 2 Department of Urology, University Hospital Munster, University of Munster, Germany 3 Department of Nuclear Medicine, University Hospital Munster, University of Munster, Germany 4 Institute of Pathology, University Hospital Bonn, University of Bonn, Germany Correspondence to: Birthe Heitkotter, email: // Keywords : PSMA, sarcoma, neovasculature, soft tissue tumor, therapy Received : August 20, 2016 Accepted : November 30, 2016 Published : December 16, 2016 Abstract Aims: PSMA (prostate specific membrane antigen) is physiologically expressed in normal prostate tissue. It is overexpressed in prostate cancer cells and has been suggested as a target for antibody-based radioligand therapy. As PSMA expression so far has not been systematically analyzed in soft tissue tumors, the current study aims at investigating a large cohort of different subtypes. Methods and Results: Immunohistochemistry was used to detect PSMA expression in 779 samples of soft tissue tumors and Ewing sarcoma as a primary bone malignancy. CD34 coexpression was employed to study PSMA expression in the neovasculature. PSMA expression was found in the tumor-associated neovasculature of 151/779 soft tissue/bone tumors (19.38%) and was more frequent in malignant tumors compared to tumors with intermediate or benign biological potential ( p =0.078). Strong neovascular PSMA expression was predominantly observed in subsets of different sarcomas including 3/20 rhabdomyosarcomas (15%), 4/21 malignant peripheral nerve sheath tumors (19.05%), 6/16 synovial sarcomas (35.29%) and 6/33 undifferentiated pleomorphic sarcomas (18.18%). Conclusion: We conclude that PSMA is expressed in the neovasculature of a subset of soft tissue tumors to a variable extent. Our observation of strong PSMA expression predominantly occurring in sarcomas might provide a rationale to evaluate PSMA-targeted radioligand therapy in these entities.