Breast Cancer 18F-ISO-1 Uptake as a Marker of Proliferation Status

  • Elizabeth S. McDonald
  • , Robert K. Doot
  • , Anthony J. Young
  • , Erin K. Schubert
  • , Julia Tchou
  • , Daniel A. Pryma
  • , Michael D. Farwell
  • , Anupma Nayak
  • , Amy Ziober
  • , Michael D. Feldman
  • , Angela DeMichele
  • , Amy S. Clark
  • , Payal D. Shah
  • , Hsiaoju Lee
  • , Sean D. Carlin
  • , Robert H. Mach
  • , David A. Mankoff

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The σ2 receptor is a potential in vivo target for measuring proliferative status in cancer. The feasibility of using N-(4-(6, 7-dimethoxy-3, 4-dihydroisoquinolin-2(1H)-yl)butyl)-2-(2-18F-fluoroethoxy)-5-methylbenzamide (18F-ISO-1) to image solid tumors in lymphoma, breast cancer, and head and neck cancer has been previously established. Here, we report the results of the first dedicated clinical trial of 18F-ISO-1 in women with primary breast cancer. Our study objective was to determine whether 18F-ISO-1 PET could provide an in vivo measure of tumor proliferative status, and we hypothesized that uptake would correlate with a tissue-based assay of proliferation, namely Ki-67 expression. Methods: Twenty-eight women with 29 primary invasive breast cancers were prospectively enrolled in a clinical trial (NCT 02284919) between March 2015 and January 2017. Each received an injection of 278–527 MBq of 18F-ISO-1 and then underwent PET/CT imaging of the breasts 50–55 min later. In vivo uptake of 18F-ISO-1 was quantitated by SUVmax and distribution volume ratios and was compared with ex vivo immunohistochemistry for Ki-67. Wilcoxon rank-sum tests assessed uptake differences across Ki-67 thresholds, and Spearman correlation tested associations between uptake and Ki-67. Results: Tumor SUVmax (median, 2.0 g/mL; range, 1.3–3.3 g/mL), partial-volume–corrected SUVmax, and SUV ratios were tested against Ki-67. Tumors stratified into the high–Ki-67 ($20%) group had SUVmax greater than the low–Ki-67 (, 20%) group (P 5 0.02). SUVmax exhibited a positive correlation with Ki-67 across all breast cancer subtypes (ρ 5 0.46, P 5 0.01, n 5 29). Partial-volume–corrected SUVmax was positively correlated with Ki-67 for invasive ductal carcinoma (ρ 5 0.51, P 5 0.02, n 5 21). Tumor–to–normal-tissue ratios and tumor distribution volume ratio did not correlate with Ki-67 (P . 0.05). Conclusion: 18F-ISO-1 uptake in breast cancer modestly correlates with an in vitro assay of proliferation.

Original languageEnglish
Pages (from-to)665-670
Number of pages6
JournalJournal of Nuclear Medicine
Volume61
Issue number5
DOIs
StatePublished - 2020
Externally publishedYes

Keywords

  • F-ISO-1
  • TMEM-97
  • breast cancer
  • proliferation
  • σ-2

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