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Preclinical Models & Translational Research

(P 248) FIBROBLAST ACTIVATION PROTEIN ALPHA -DIRECTED IMAGING AND THERAPY OF SOLITARY FIBROUS TUMOR

Location: The Liffey, Level 1

    Author(s)

  • Rainer Hamacher, MD

    Medical Oncology
    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

    • Co-Author(s)

  • Kim M. Pabst, MD (she/her/hers)

    Physician in training
    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • PC

    Phyllis F. Cheung, PhD

    Senior scientist
    Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • CH

    Christoph E. E. Heilig, MD

    Clinician Scientist
    Department of Translational Medical Oncology, National Center for Tumor Diseases (NCT) Heidelberg and German Cancer Research Center (DKFZ)
    Heidelberg, Baden-Wurttemberg, Germany

  • JH

    Jennifer Hüllein, PhD

    Computational Oncology, Molecular Precision Oncology Program, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT)
    Heidelberg, Baden-Wurttemberg, Germany

  • SL

    Sven-Thorsten Liffers, PhD

    Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen
    Essen, Baden-Wurttemberg, Germany

  • SB

    Sabrina Borchert, PhD

    Institute of Pathology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • Pedro Fragoso Costa, Msc, Dr

    Chief Medical Physicist
    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • BS

    Benedikt M. Schaarschmidt, MD

    Department of Diagnostic and Interventional Radiology and Neuroradiology, West German Cancer Center, University Hospital Essen, Essen
    Essen, Nordrhein-Westfalen, Germany

  • LK

    Lukas Kessler, MD

    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • MM

    Monika A. Miera, n/a

    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • MD

    Margret Droste, PhD

    Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • MA

    Merve Akbulut, n/a

    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • Johanna Falkenhorst, MD (she/her/hers)

    Medical Oncologist
    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • FZ

    Fadi Zarrad, PhD

    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • KK

    Karina Kostbade, MD

    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • IM

    Ilektra A. Mavroeidi, MD

    Resident doctor
    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • HG

    Hanno Glimm, MD (he/him/his)

    Head of Department
    Translational Medical Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden
    Dresden, Sachsen, Germany

  • LU

    Lale Umutlu, MD

    Department of Diagnostic and Interventional Radiology and Neuroradiology, West German Cancer Center, University Hospital Essen, Essen
    Essen, Nordrhein-Westfalen, Germany

  • MS

    Martin Schuler, MD

    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • DH

    Daniel Hübschmann, PhD

    Computational Oncology, Molecular Precision Oncology Program, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT)
    Heidelberg, Baden-Wurttemberg, Germany

  • Sebastian Bauer, MD (he/him/his)

    Attending, Director Sarcoma Center
    Department of Medical Oncology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • Stefan Fröhling, MD (he/him/his)

    Division Head
    Department of Translational Medical Oncology, National Center for Tumor Diseases (NCT) Heidelberg and German Cancer Research Center (DKFZ)
    Heidelberg, Baden-Wurttemberg, Germany

  • KH

    Ken Herrmann, MD

    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • JS

    Jens T. Siveke, MD

    Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • HS

    Hans-Ulrich Schildhaus, MD

    Institute of Pathology, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

  • WF

    Wolfgang P. Fendler, MD

    Department of Nuclear Medicine, West German Cancer Center, University Hospital Essen
    Essen, Nordrhein-Westfalen, Germany

Objective: Fibroblast activation protein alpha (FAP) is expressed at high levels in several tumors. Here, we report the expression pattern of FAP in solitary fibrous tumor (SFT) and its potential use as radiotheranostic target.

Methods: We analyzed FAP mRNA and protein expression in biopsies from SFT patients using immunohistochemistry and multiplex immunofluorescence. Tracer uptake and detection efficacy were assessed in patients undergoing 68Ga-FAPI-46 and 18F-FDG PET. 90Y-FAPI-46 radioligand therapy (RLT) was offered to eligible patients with progressive SFT.

Results: Among 813 patients and 126 tumor entities analyzed from the prospective observational MASTER trial of the German Cancer Consortium, SFT (n=34) had the highest median FAP mRNA expression. Protein expression was confirmed in tumor biopsies from 29 of 38 SFT patients (76%) in an independent cohort. Most cases showed intermediate to high FAP expression by immunohistochemistry (24 of 38 samples, 63%), which was primarily located on tumor cells. 19 patients who underwent 68Ga-FAPI-46 PET imaging demonstrated significantly higher tumor uptake with SUVmax 13.2 (IQR 10.2) and better mean detection efficacy of 94.5% (SEM 4.2%) as compared to 18F-FDG PET (SUVmax 3.2, IQR 3.1; 77.3%, SEM 5.5%). Eleven patients received a total of 34 cycles (median 3; IQR 2) 90Y-FAPI-46 RLT, resulting in disease control in nine patients (82%). Median progression free survival was 227 days (IQR 220).

Conclusion: FAP is highly expressed by SFT and may serve as target for imaging and therapy. Further studies are warranted to define the role of FAP-directed theranostic in the care of SFT patients.