68GaPentixafor-PET/CT for imaging of chemokine receptor 4 expression in small cell lung cancer - initial experience

// Constantin Lapa 1,* , Katharina Lückerath 1,* , Martina Rudelius 2 , Jan-Stefan Schmid 1 , Alexander Schoene 3 , Andreas Schirbel 1 , Samuel Samnick 1 , Theo Pelzer 4 , Andreas K. Buck 1 , Saskia Kropf 5 , Hans-Jürgen Wester 6 and Ken Herrmann 1,7 1 Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany 2 Institute for Pathology, University of Würzburg, Würzburg, Germany 3 Department of Internal Medicine, Caritas Hospital Bad Mergentheim, Bad Mergentheim, Germany 4 Department of Internal Medicine, University Hospital Würzburg, Würzburg, Germany 5 Scintomics GmbH, Fürstenfeldbruck, Germany 6 Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany 7 Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA * These authors have contributed equally to this work Correspondence to: Constantin Lapa, email: // Keywords : small cell lung cancer, SCLC, molecular imaging, CXCR4, PET Received : January 11, 2016 Accepted : January 16, 2016 Published : January 28, 2016 Abstract Chemokine receptor CXCR4 is a key factor for tumor growth and metastasis in several types of human cancer. This study investigated the feasibility of CXCR4-directed imaging of small cell lung cancer (SCLC) with positron emission tomography/computed tomography (PET/CT) using the radiolabelled chemokine ligand 68 GaPentixafor. 10 patients with primarily diagnosed (n=3) or pre-treated (n=7) SCLC (n=9) or large cell neuroendocrine carcinoma of the lung (LCNEC, n=1) underwent 68 GaPentixafor-PET/CT. 2- 18 Ffluoro-2-deoxy-D-glucose ( 18 FFDG, n=6) and/or somatostatin receptor (SSTR)-directed PET/CT with 68 GaDOTATOC (n=5) and immunohistochemistry (n=10) served as standards of reference. CXCR4-PET was positive in 8/10 patients and revealed more lesions with significantly higher tumor-to-background ratios than SSTR-PET. Two patients who were positive on 18 FFDG-PET were missed by CXCR4-PET, in the remainder 68 GaPentixafor detected an equal (n=2) or higher (n=2) number of lesions. CXCR4 expression of tumor lesions could be confirmed by immunohistochemistry. Non-invasive imaging of CXCR4 expression in SCLC is feasible. 68 GaPentixafor as a novel PET tracer might serve as readout for confirmation of CXCR4 expression as prerequisite for potential CXCR4-directed treatment including receptor-radio(drug)peptide therapy.