ImmunoPET of tissue factor expression in triple-negative breast cancer with a radiolabeled antibody Fab fragment

Sixiang Shi, Hao Hong, Hakan Orbay, Stephen A. Graves, Yunan Yang, Jakob D. Ohman, Bai Liu, Robert J. Nickles, Hing C. Wong, Weibo Cai

Research output: Journal article publicationJournal articleAcademic researchpeer-review

23 Citations (Scopus)

Abstract

Purpose: To date, there is no effective therapy for triple-negative breast cancer (TNBC), which has a dismal clinical outcome. Upregulation of tissue factor (TF) expression leads to increased patient morbidity and mortality in many solid tumor types, including TNBC. Our goal was to employ the Fab fragment of ALT-836, a chimeric anti-human TF mAb, for PET imaging of TNBC, which can be used to guide future TNBC therapy. Methods: ALT-836-Fab was generated by enzymatic papain digestion. SDS-PAGE and FACS studies were performed to evaluate the integrity and TF binding affinity of ALT-836-Fab before NOTA conjugation and 64Cu-labeling. Serial PET imaging and biodistribution studies were carried out to evaluate the tumor targeting efficacy and pharmacokinetics in the MDA-MB-231 TNBC model, which expresses high levels of TF on the tumor cells. Blocking studies, histological assessment, as well as RT-PCR were performed to confirm TF specificity of 64Cu-NOTA-ALT-836-Fab. Results: ALT-836-Fab was produced with high purity, which exhibited superb TF binding affinity and specificity. Serial PET imaging revealed rapid and persistent tumor uptake of 64Cu-NOTA-ALT-836-Fab (5.1 ± 0.5 %ID/g at 24 h post-injection; n = 4) and high tumor/muscle ratio (7.0 ± 1.2 at 24 h post-injection; n = 4), several-fold higher than that of the blocking group and tumor models that do not express significant level of TF, which was confirmed by biodistribution studies. TF specificity of the tracer was also validated by histology and RT-PCR. Conclusion: 64Cu-NOTA-ALT-836-Fab exhibited prominent tissue factor targeting efficiency in MDA-MB-231 TNBC model. The use of a Fab fragment led to fast tumor uptake and good tissue/muscle ratio, which may be translated into same-day immunoPET imaging in the clinical setting to improve TNBC patient management.

Original languageEnglish
Pages (from-to)1295-1303
Number of pages9
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume42
Issue number8
Early online date24 Mar 2015
DOIs
Publication statusPublished - Jul 2015
Externally publishedYes

Keywords

  • Antibody fragment
  • Fab
  • Positron emission tomography (PET)
  • Tissue factor (TF)
  • Triple-negative breast cancer (TNBC)

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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