Prospective Clinical Trial of 18F-Fluciclovine PET/CT for Determining the Response to Neoadjuvant Therapy in Invasive Ductal and Invasive Lobular Breast Cancers

Abstract

18F-labeled 1-amino-3-fluorocyclobutane-1-carboxylic acid (18F-fluciclovine) is a leucine analog radiotracer that depicts amino acid transport into cells. 18F-fluciclovine PET/CT visualizes malignancy, including prostate cancer, invasive ductal breast cancer, and invasive lobular breast cancer. Whether changes in 18F-fluciclovine avidity reflect changes in tumor burden resulting from treatment has not been shown. In this prospective clinical trial (clinical trials.gov: NCT01864083), changes in 18F-fluciclovine avidity after neoadjuvant therapy were compared to breast cancer therapy response, as determined by residual tumor burden on pathology, were evaluated. Methods: Twenty-four women with a new diagnosis of locally advanced invasive ductal breast cancer (n = 18) or invasive lobular breast cancer (n = 6) underwent 18F-fluciclovine PET/CT before and after the completion of neoadjuvant systemic therapy. SUVmax, SUVmean, metabolic tumor volume, and total lesion avidity were obtained for the primary breast tumor, axillary lymph nodes, and extraaxillary lymph nodes on each examination and corrected for background 18F-fluciclovine avidity. The relationship between changes in 18F-fluciclovine avidity and the percentage of reduction of tumor on pathology was assessed with the Spearman rank correlation. Results: The median decrease in the corrected SUVmax of the primary breast lesions was 99% (range, 33%-100%). The median reduction of tumor on pathology was 92% (range, 10%-100%). Changes in 18F-fluciclovine avidity were strongly correlated with the percentage of reduction of tumor on pathology (Spearman ρ, 0.79; 95% CI, 0.56-0.90; P < 0.001). Conclusion: Changes in 18F-fluciclovine avidity strongly correlated with the tumor response on pathology in this pilot study.

Keywords: 18F-fluciclovine; PET/CT; ductal breast cancer; lobular breast cancer; response.

© 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Figures

FIGURE 1.

Time–activity curve for primary breast malignancy in representative patient. 18F-fluciclovine uptake was rapid, peaking at 5–10 min, and then slowly decreased until 30 min.

FIGURE 2.

Reduction in 18F-fluciclovine avidity after neoadjuvant therapy in 52-y-old woman with grade 2 ER−/HER2+ IDC. (A–C) Axial 18F-fluciclovine PET (A), axial CT (B), and axial fused (C) images at baseline show 18F-fluciclovine–avid primary breast mass (solid arrow) and 18F-fluciclovine–avid axillary node metastases (broken arrow). (D–F) Axial 18F-fluciclovine PET (D), axial CT (E), and axial fused (F) images after neoadjuvant therapy show decrease in 18F-fluciclovine avidity of all lesions to background levels. Pathology revealed complete pathologic response, with no residual tumor.

FIGURE 3.

Scatterplot of percentage of change in corrected SUVmax vs. percentage of tumor volume reduction on pathology after neoadjuvant therapy. ρ = Spearman ρ.