Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jun;60(6):801-805.
doi: 10.2967/jnumed.119.227967. Epub 2019 Apr 6.

68Ga-FAPI PET/CT: Tracer Uptake in 28 Different Kinds of Cancer

Clemens Kratochwil  1 , Paul Flechsig  2   3 , Thomas Lindner  2 , Labidi Abderrahim  2 , Annette Altmann  2   4 , Walter Mier  2 , Sebastian Adeberg  5   6 , Hendrik Rathke  2 , Manuel Röhrich  2 , Hauke Winter  3   7 , Peter K Plinkert  8 , Frederik Marme  9   10 , Matthias Lang  11 , Hans-Ulrich Kauczor  3   12 , Dirk Jäger  13   14 , Jürgen Debus  5   6   15 , Uwe Haberkorn  2   3   4 , Frederik L Giesel  2
Affiliations

68Ga-FAPI PET/CT: Tracer Uptake in 28 Different Kinds of Cancer

Clemens Kratochwil et al. J Nucl Med. 2019 Jun.

Abstract

The recent development of quinoline-based PET tracers that act as fibroblast-activation-protein inhibitors (FAPIs) demonstrated promising preclinical and clinical results. FAP is overexpressed by cancer-associated fibroblasts of several tumor entities. Here, we quantify the tumor uptake on 68Ga-FAPI PET/CT of various primary and metastatic tumors to identify the most promising indications for future application. Methods:68Ga-FAPI PET/CT scans were requested by various referring physicians according to individual clinical indications that were considered insufficiently covered by 18F-FDG PET/CT or other imaging modalities. All PET/CT was performed 1 h after injection of 122-312 MBq of 68Ga-FAPI-04. We retrospectively identified 80 patients with histopathologically proven primary tumors or metastases or radiologically unequivocal metastatic lesions of histologically proven primary tumors. Tumor uptake was quantified by SUVmax and SUVmean (60% isocontour). Results: Eighty patients with 28 different tumor entities (54 primary tumors and 229 metastases) were evaluated. The highest average SUVmax (>12) was found in sarcoma, esophageal, breast, cholangiocarcinoma, and lung cancer. The lowest 68Ga-FAPI uptake (average SUVmax < 6) was observed in pheochromocytoma, renal cell, differentiated thyroid, adenoid cystic, and gastric cancer. The average SUVmax of hepatocellular, colorectal, head-neck, ovarian, pancreatic, and prostate cancer was intermediate (SUV 6-12). SUV varied across and within all tumor entities. Because of low background in muscle and blood pool (SUVmax < 2), the tumor-to-background contrast ratios were more than 3-fold in the intermediate and more than 6-fold in the high-intensity uptake group. Conclusion: Several highly prevalent cancers presented with remarkably high uptake and image contrast on 68Ga-FAPI PET/CT. The high and rather selective tumor uptake may open up new applications for noninvasive tumor characterization, staging examinations, or radioligand therapy.

Keywords: FAPI; PET/CT; breast cancer; colorectal cancer; lung cancer.

PubMed Disclaimer

Figures

FIGURE 1.
FIGURE 1.
Neither mean, median, nor range of SUVmax of 68Ga-FAPI-04 PET differs significantly between primary tumors and metastases.
FIGURE 2.
FIGURE 2.
Average SUVmax of 68Ga-FAPI PET/CT in various tumor entities. Low, intermediate, and high uptake was defined by cutoff at SUVs 6 and 12. By comparison, average background (blood pool) was found to have SUV 1.4. Ca = cancer; CCC = cholangiocellular carcinoma; CUP = carcinoma of unknown primary; HCC = hepatocellular carcinoma; NET = neuroendocrine tumor.
FIGURE 3.
FIGURE 3.
Maximum-intensity projections of 68Ga-FAPI PET/CT in patients reflecting 15 different histologically proven tumor entities (sorted by uptake in descending order). Ca = cancer; CCC = cholangiocellular carcinoma; CUP = carcinoma of unknown primary; MTC = medullary thyroid cancer; NET = neuroendocrine tumor.
FIGURE 4.
FIGURE 4.
Maximum-intensity projection (A) of patient with colorectal carcinoma. Because of low physiologic background uptake, tiny lesions in lung (B) and liver (D) were detected by 68Ga-FAPI-04 PET/CT and measured in dedicated CT of lung (C) and hepatic MRI (E) with long-axis diameters of 1 cm. *Primary tumor in left colon flexure. Red arrow = unspecific uptake in uterus.
FIGURE 5.
FIGURE 5.
Among others, one clinical application for 68Ga-FAPI PET/CT can be to improve gross tumor volume delineation in preparation for external-beam radiotherapy—in this case, squamous cell carcinoma of neck with local lymph node metastases. From left to right: whole-body maximum-intensity projections, coronal PET slice through head/neck tumor, its fusion with coregistered CT, PET-segmented target-volume definition for external-beam radiotherapy.
See this image and copyright information in PMC

Comment in

References

    1. Siveke JT. Fibroblast-activating protein: targeting the roots of the tumor microenvironment. J Nucl Med. 2018;59:1412–1414. - PubMed
    1. Hamson EJ, Keane FM, Tholen S, Schilling O, Gorrell MD. Understanding fibroblast activation protein (FAP): substrates, activities, expression and targeting for cancer therapy. Proteomics Clin Appl. 2014;8:454–463. - PubMed
    1. Garin-Chesa P, Old LJ, Rettig WJ. Cell surface glycoprotein of reactive stromal fibroblasts as a potential antibody target in human epithelial cancers. Proc Natl Acad Sci USA. 1990;87:7235–7239. - PMC - PubMed
    1. Loktev A, Lindner T, Mier W, et al. A tumor-imaging method targeting cancer-associated fibroblasts. J Nucl Med. 2018;59:1423–1429. - PMC - PubMed
    1. Lindner T, Loktev A, Altmann A, et al. Development of quinoline based theranostic ligands for the targeting of fibroblast activation protein. J Nucl Med. April 6, 2018. [Epub ahead of print]. - PubMed

MeSH terms