Artigo Acesso aberto Revisado por pares

Superior Tumor Detection for 68 Ga-FAPI-46 Versus 18 F-FDG PET/CT and Conventional CT in Patients with Cholangiocarcinoma

2023; Society of Nuclear Medicine and Molecular Imaging; Volume: 64; Issue: 7 Linguagem: Inglês

10.2967/jnumed.122.265215

ISSN

1535-5667

Autores

Kim M. Pabst, Marija Trajkovic‐Arsic, Phyllis F. Cheung, Simone Ballke, Katja Steiger, Timo Bartel, Benedikt M. Schaarschmidt, Aleksandar Milošević, Robert Seifert, Michael A. Nader, Lukas Kessler, Jens T. Siveke, Katharina Lueckerath, Stefan Kasper, Ken Herrmann, Nader Hirmas, Hartmut Schmidt, Rainer Hamacher, Wolfgang P. Fendler,

Tópico(s)

Cholangiocarcinoma and Gallbladder Cancer Studies

Resumo

Management of cholangiocarcinoma is among other factors critically determined by accurate staging. Here, we aimed to assess the accuracy of PET/CT with the novel cancer fibroblast–directed 68 Gafibroblast activation protein (FAP) inhibitor (FAPI)-46 tracer for cholangiocarcinoma staging and management guidance. Methods: Patients with cholangiocarcinoma from a prospective observational trial were analyzed. 68 Ga-FAPI-46 PET/CT detection efficacy was compared with 18 F-FDG PET/CT and conventional CT. SUV max /tumor-to-background ratio (Wilcoxon test) and separately uptake for tumor grade and location (Mann–Whitney U test) were compared. Immunohistochemical FAP and glucose transporter 1 (GLUT1) expression of stromal and cancer cells was analyzed. The impact on therapy management was investigated by pre- and post-PET/CT questionnaires sent to the treating physicians. Results: In total, 10 patients (6 with intrahepatic cholangiocarcinoma and 4 with extrahepatic cholangiocarcinoma; 6 with grade 2 tumor and 4 with grade 3 tumor) underwent 68 Ga-FAPI-46 PET/CT and conventional CT; 9 patients underwent additional 18 F-FDG PET/CT. Immunohistochemical analysis was performed on the entire central tumor plain in 6 patients. Completed questionnaires were returned in 8 cases. Detection rates for 68 Ga- FAPI-46 PET/CT, 18 F-FDG PET/CT, and CT were 5, 5, and 5, respectively, for primary tumor; 11, 10, and 3, respectively, for lymph nodes; and 6, 4, and 2, respectively, for distant metastases. 68 Ga-FAPI-46 versus 18 F-FDG PET/CT SUV max for primary tumor, lymph nodes, and distant metastases was 14.5 versus 5.2 ( P = 0.043), 4.7 versus 6.7 ( P = 0.05), and 9.5 versus 5.3 ( P = 0.046), respectively, and tumor-to-background ratio (liver) was 12.1 versus 1.9 ( P = 0.043) for primary tumor. Grade 3 tumors demonstrated a significantly higher 68 Ga-FAPI-46 uptake than grade 2 tumors (SUV max , 12.6 vs. 6.4; P = 0.009). Immunohistochemical FAP expression was high on tumor stroma (~90% of cells positive), whereas GLUT1 expression was high on tumor cells (~80% of cells positive). Overall, average expression intensity was estimated as grade 3 for FAP and grade 2 for GLUT1. Positive 68 Ga-FAPI-46 PET findings led to a consequent biopsy workup and diagnosis of cholangiocarcinoma in 1 patient. However, patient treatment was not adjusted on the basis of 68 Ga-FAPI-46 PET. Conclusion: 68 Ga-FAPI-46 demonstrated superior radiotracer uptake, especially in grade 3 tumors, and lesion detection in patients with cholangiocarcinoma. In line with this result, immunohistochemistry demonstrated high FAP expression on tumor stroma. Accuracy is under investigation in an ongoing investigator-initiated trial.

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