Fibroblast Activation Protein α–Directed Imaging and Therapy of Solitary Fibrous Tumor

• DOI: 10.2967/jnumed.123.266411
• Publication Date: 2024-01-10T05:27:45Z
• Authors: Rainer Hamacher; Kim M. Pabst; Phyllis F. Cheung; Christoph E. Heilig; Jennifer Hüllein; Sven-Thorsten Lif...; Sabrina Borchert; Pedro Fragoso Costa; Benedikt M. Schaa...; Lukas Kessler; Monika A. Miera; Margret Droste; Merve Akbulut; Johanna Falkenhorst; Fadi Zarrad; Karina Kostbade; Ilektra A. Mavroeidi; Hanno Glimm; Lale Umutlu; Martin Schuler; Daniel Hübschmann; Sebastian Bauer; Stefan Fröhling; Ken Herrmann; Jens T. Siveke; Hans-Ulrich Schil...; Wolfgang P. Fendler
• Keywords: Interquartile range; Solitary Fibrous Tumor

Fibroblast activation protein α (FAPα) is expressed at high levels in several types of tumors. Here, we report the expression pattern FAPα solitary fibrous tumor (SFT) and its potential use as a radiotheranostic target. <b>Methods:</b> We analyzed messenger RNA biopsy samples from SFT patients using immunohistochemistry multiplexed immunofluorescence. Tracer uptake detection efficacy were assessed undergoing clinical ⁶⁸Ga-FAPα inhibitor (FAPI)–46 PET,¹⁸F-FDG PET, contrast-enhanced CT. ⁹⁰Y-FAPI-46 radioligand therapy was offered to eligible with progressive SFT. <b>Results:</b> Among 813 126 entities prospective observational MASTER program German Cancer Consortium, (<i>n</i> = 34) had highest median expression. Protein confirmed biopsies 29 38 (76%) an independent cohort. Most cases showed intermediate by (24/38 samples, 63%), which located primarily on cell surface. Nineteen who underwent ⁶⁸Ga-FAPI-46 PET imaging demonstrated significantly increased uptake, SUV_max 13.2 (interquartile range [IQR], 10.2), improved mean 94.5% (SEM, 4.2%), compared ¹⁸F-FDG (SUV_max, 3.2 [IQR, 3.1]; efficacy, 77.3% [SEM, 5.5%]). Eleven received total 34 cycles (median, 3 2 cycles]) therapy, resulted disease control 9 (82%). Median progression-free survival 227 d (IQR, 220 d). <b>Conclusion:</b> highly may serve target for therapy. Further studies are warranted define role FAPα-directed theranostics care patients.