Journal Article

DKFZ-2026-00598

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Comparison between [68Ga]Ga-FAPI-46 and [18F]FDG PET/CT uptake in luminal-like vs. HER2-positive breast cancer.

Küper, A. T.DKFZ* ; Vaz, S. C. ; Pabst, K. M.DKFZ* ; Ciuciulkaite, I.DKFZ* ; Mavroeidi, I. A. ; Hamacher, R. ; Welt, A.DKFZ* ; Hammersen, N.DKFZ* ; Costa, P. F.DKFZ* ; Djaileb, L. ; Seifert, R. ; Umutlu, L. ; Schuler, M.DKFZ* ; Herrmann, K.DKFZ* ; Fendler, W. P.DKFZ* ; Kümmel, S. ; Kersting, D.DKFZ*

2026
Springer Heidelberg

Abstract: Fibroblast activation protein (FAP)-targeted tracers have emerged as promising agents for breast cancer imaging, with recent studies demonstrating PET performance comparable to or surpassing, that of [18F]FDG. Nevertheless, data comparing [68Ga]Ga-FAPI-46 and [18F]FDG uptake in hormone receptor and/or HER2-positive breast cancer (luminal-like vs HER2-positive) remain scarce. Aim of this study was to investigate the diagnostic performance of [68Ga]Ga-FAPI-46 versus [18F]FDG PET/CT in patients with hormone-receptor and/or HER2-positive breast cancer, and to evaluate the uptake of both tracers stratified by molecular subtypes (luminal-like vs HER2-positive). A sub-analysis of a prospective observational trial (NCT04571086) was conducted. Patients with histologically confirmed, hormone receptor- and/or HER2-positive breast cancer who underwent whole-body [68Ga]Ga-FAPI-46 and [18F]FDG PET/CT in the same week for initial staging or follow-up were included. [68Ga]Ga-FAPI-46 or [18F]FDG PET-positive lesions were defined as visually increased lesion uptake compared to adjacent organ background. Semi-automatic segmentation was performed to determine SUVmax, SUVpeak, TLRpeak, total number of lesions, total tumour volume, and total tumour SUV mean. Data were compared between molecular subtypes (luminal-like vs HER2-positive).Thirteen patients were included. Overall, the detection performance was comparable between [68Ga]Ga-FAPI-46 and [18F]FDG PET. The semi-quantitative analysis showed comparable mean uptake values in breast cancer lesions on [68Ga]Ga-FAPI-46 and [18F]FDG PET/CT (SUVmax: 13.4 vs. 12.9; TLRpeak: 5.6 vs. 4.5) and revealed no significant differences in the median lesion count (4.5 vs. 5), mean total tumour volume (71.5 vs. 73.2 mL), or mean total tumour SUVmean (5.4 vs. 5.4). No substantial differences between molecular subtypes (luminal-like vs. HER2-positive) were observed.In this small exploratory cohort, comparable uptake patterns in [68Ga]Ga-FAPI-46- and [18F]FDG-positive breast cancer lesions were observed across subtypes, underscoring the potential of [68Ga]Ga-FAPI-46 as a versatile imaging tool. Future studies in larger cohorts are warranted to explore the potential of FAP-targeted theranostics in different breast cancer subtypes.68-Ga-FAPI-PET for Tumor Detection: A Prospective Observational Trial, NCT04571086, 09-15-2020, https://clinicaltrials.gov/study/NCT04571086.

Keyword(s): Breast cancer ; FAPI ; FDG ; HER2 ; Hormone receptors ; Luminal-like ; PET ; Pan-tumour imaging ; Theranostics

Note: epub

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Contributing Institute(s):

1. DKTK Koordinierungsstelle Essen/Düsseldorf (ED01)

Research Program(s):

1. 899 - ohne Topic (POF4-899) (POF4-899)

Appears in the scientific report 2026

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Database coverage:
; ; Article Processing Charges ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; DOAJ Seal ; Ebsco Academic Search ; Essential Science Indicators ; Fees ; IF < 5 ; JCR ; PubMed Central ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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