RT Journal Article
SR Electronic
T1 Superior Tumor Detection for <sup>68</sup>Ga-FAPI-46 Versus <sup>18</sup>F-FDG PET/CT and Conventional CT in Patients with Cholangiocarcinoma
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.122.265215
DO 10.2967/jnumed.122.265215
A1 Pabst, Kim M.
A1 Trajkovic-Arsic, Marija
A1 Cheung, Phyllis F.Y.
A1 Ballke, Simone
A1 Steiger, Katja
A1 Bartel, Timo
A1 Schaarschmidt, Benedikt M.
A1 Milosevic, Aleksandar
A1 Seifert, Robert
A1 Nader, Michael
A1 Kessler, Lukas
A1 Siveke, Jens T.
A1 Lueckerath, Katharina
A1 Kasper, Stefan
A1 Herrmann, Ken
A1 Hirmas, Nader
A1 Schmidt, Hartmut H.
A1 Hamacher, Rainer
A1 Fendler, Wolfgang P.
YR 2023
UL http://jnm.snmjournals.org/content/early/2023/04/06/jnumed.122.265215.abstract
AB 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 68Gafibroblast activation protein (FAP) inhibitor (FAPI)-46 tracer for cholangiocarcinoma staging and management guidance. Methods: Patients with cholangiocarcinoma from a prospective observational trial were analyzed. 68Ga-FAPI-46 PET/CT detection efficacy was compared with 18F-FDG PET/CT and conventional CT. SUVmax/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 68Ga-FAPI-46 PET/CT and conventional CT; 9 patients underwent additional 18F-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 68Ga- FAPI-46 PET/CT, 18F-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. 68Ga-FAPI-46 versus 18F-FDG PET/CT SUVmax 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 68Ga-FAPI-46 uptake than grade 2 tumors (SUVmax, 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 68Ga-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 68Ga-FAPI-46 PET. Conclusion: 68Ga-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.