ImmunoPET of tissue factor expression in triple-negative breast cancer with a radiolabeled antibody Fab fragment
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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.
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.
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.
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.
KeywordsTriple-negative breast cancer (TNBC) Positron emission tomography (PET) Tissue factor (TF) Antibody fragment Fab
This work was supported in part by the University of Wisconsin-Madison, the National Institutes of Health (NIBIB/NCI 1R01CA169365, P30CA014520, and T32CA009206), the Department of Defense (W81XWH-11-1-0644 and W81XWH-11-1-0648), and the American Cancer Society (125246-RSG-13-099-01-CCE).
Compliance with ethical standards
Conflicts of interest
Bai Liu and Hing C. Wong are employees of Altor Bioscience Corporation. The other authors declare that they had no conflicts of interest.
Statement of human rights
This article does not describe any studies with human participants performed by any of the authors.
Statement on the welfare of animals
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
- 2.van Scheltinga AG T, Berghuis P, Nienhuis HH, Timmer-Bosscha H, Pot L, Gaykema SB, et al. Visualising dual downregulation of insulin-like growth factor receptor-1 and vascular endothelial growth factor-A by heat shock protein 90 inhibition effect in triple negative breast cancer. Eur J Cancer. 2014;50:2508–16.CrossRefGoogle Scholar
- 34.Finn RS, Dering J, Ginther C, Wilson CA, Glaspy P, Tchekmedyian N, et al. Dasatinib, an orally active small molecule inhibitor of both the src and abl kinases, selectively inhibits growth of basal-type/”triple-negative” breast cancer cell lines growing in vitro. Breast Cancer Res Treat. 2007;105:319–26.PubMedCrossRefGoogle Scholar