1. Potential and pitfalls of 89Zr-immuno-PET to assess target status: 89Zr-trastuzumab as an example.
- Author
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Huisman, Marc C., Menke-van der Houven van Oordt, C. Willemien, Zijlstra, Josée M., Hoekstra, Otto S., Boellaard, Ronald, van Dongen, Guus A. M. S., Shah, Dhaval K., and Jauw, Yvonne W. S.
- Subjects
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TRASTUZUMAB , *MONOCLONAL antibodies - Abstract
Background: 89Zirconium-immuno-positron emission tomography (89Zr-immuno-PET) is used for assessment of target status to guide antibody-based therapy. We aim to determine the relation between antibody tumor uptake and target concentration to improve future study design and interpretation. Methods: The relation between tumor uptake and target concentration was predicted by mathematical modeling of 89Zr-labeled antibody disposition in the tumor. Literature values for trastuzumab kinetics were used to provide an example. Results: 89Zr-trastuzumab uptake initially increases with increasing target concentration, until it levels off to a constant value. This is determined by the total administered mass dose of trastuzumab. For a commonly used imaging dose of 50 mg 89Zr-trastuzumab, uptake can discriminate between immunohistochemistry score (IHC) 0 versus 1–2–3. Conclusion: The example for 89Zr-trastuzumab illustrates the potential to assess target expression. The pitfall of false-positive findings depends on the cut-off to define clinical target positivity (i.e., IHC 3) and the administered mass dose. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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