Measuring the pharmacodynamic effects of a novel Hsp90 inhibitor on HER2/ neu expression in mice using (89)Zr-DFO-trastuzumab Journal Article

Authors: Holland, J. P.; Caldas-Lopes, E.; Divilov, V.; Longo, V. A.; Taldone, T.; Zatorska, D.; Chiosis, G.; Lewis, J. S.
Article Title: Measuring the pharmacodynamic effects of a novel Hsp90 inhibitor on HER2/ neu expression in mice using (89)Zr-DFO-trastuzumab
Abstract: Background:The positron-emitting radionuclide 89Zr (t 1/2 = 3.17 days) was used to prepare 89Zr-radiolabeled trastuzumab for use as a radiotracer for characterizing HER2/neu-positive breast tumors. In addition, pharmacodynamic studies on HER2/ neu expression levels in response to therapeutic doses of PU-H71 (a specific inhibitor of heat-shock protein 90 [Hsp90]) were conducted. Methodology/Principal Findings: Trastuzumab was functionalized with desferrioxamine B (DFO) and radiolabeled with [ 89Zr]Zr-oxalate at room temperature using modified literature methods. ImmunoPET and biodistribution experiments in female, athymic nu/nu mice bearing sub-cutaneous BT-474 (HER2/neu positive) and/or MDA-MB-468 (HER2/neu negative) tumor xenografts were conducted. The change in 89Zr-DFO- trastuzumab tissue uptake in response to high- and low-specific-activity formulations and co-administration of PU-H71 was evaluated by biodistribution studies, Western blot analysis and immunoPET. 89Zr-DFO-trastuzumab radiolabeling proceeded in high radiochemical yield and specific-activity 104.3±2.1 MBq/mg (2.82±0.05 mCi/mg of mAb). In vitro assays demonstrated >99% radiochemical purity with an immunoreactive fraction of 0.87±0.07. In vivo biodistribution experiments revealed high specific BT-474 uptake after 24, 48 and 72 h (64.68±13.06%ID/g; 71.71±10.35%ID/g and 85.18±11.10%ID/g, respectively) with retention of activity for over 120 h. Pre-treatment with PU-H71 was followed by biodistribution studies and immunoPET of 89Zr-DFO-trastuzumab. Expression levels of HER2/neu were modulated during the first 24 and 48 h post-administration (29.75±4.43%ID/g and 41.42±3.64%ID/g, respectively). By 72 h radiotracer uptake (73.64±12.17%ID/g) and Western blot analysis demonstrated that HER2/neu expression recovered to baseline levels. Conclusions/Significance: The results indicate that 89Zr-DFO- trastuzumab provides quantitative and highly-specific delineation of HER2/neu positive tumors, and has potential to be used to measure the efficacy of long-term treatment with Hsp90 inhibitors, like PU-H71, which display extended pharmacodynamic profiles. Copyright: © 2010 Holland et al.
Keywords: controlled study; unclassified drug; human cell; nonhuman; positron emission tomography; mouse; mus; pharmacodynamics; epidermal growth factor receptor 2; animal experiment; animal model; in vivo study; in vitro study; tumor xenograft; drug specificity; gene expression regulation; drug distribution; drug uptake; isotope labeling; nude mouse; breast tumor; western blotting; heat shock protein 90 inhibitor; pu h71; tracer; trastuzumab; zirconium; zirconium 89; deferoxamine; oxalate zr 89; cell strain; cell strain bt 474; cell strain mda mb 468
Journal Title: PLoS ONE
Volume: 5
Issue: 1
ISSN: 1932-6203
Publisher: Public Library of Science  
Date Published: 2010-01-25
Start Page: e8859
Language: English
DOI: 10.1371/journal.pone.0008859
PROVIDER: scopus
PMCID: PMC2810330
PUBMED: 20111600
Notes: --- - "Cited By (since 1996): 1" - "Export Date: 20 April 2011" - "Art. No.: e8859" - "Source: Scopus"
Citation Impact
MSK Authors
  1. Jason Philip Holland
    31 Holland
  2. Gabriela Chiosis
    245 Chiosis
  3. Tony Taldone
    90 Taldone
  4. Jason S Lewis
    354 Lewis
  5. Vadim Divilov
    16 Divilov
  6. Valerie Ann Longo
    35 Longo