@article {Verel1663, author = {Iris Verel and Gerard W.M. Visser and Ronald Boellaard and Otto C. Boerman and Julliette van Eerd and Gordon B. Snow and Adriaan A. Lammertsma and Guus A.M.S van Dongen}, title = {Quantitative 89Zr Immuno-PET for In Vivo Scouting of 90Y-Labeled Monoclonal Antibodies in Xenograft-Bearing Nude Mice }, volume = {44}, number = {10}, pages = {1663--1670}, year = {2003}, publisher = {Society of Nuclear Medicine}, abstract = {Immuno-PET as a scouting procedure before radioimmunotherapy (RIT) aims at the confirmation of tumor targeting and the accurate estimation of radiation dose delivery to both tumor and normal tissues. Immuno-PET with 89Zr-labeled monoclonal antibodies (mAbs) and 90Y-mAb RIT might form such a valuable combination. In this study, the biodistribution of 89Zr-labeled and 88Y-labeled mAb (88Y as substitute for 90Y) was compared and the quantitative imaging performance of 89Zr immuno-PET was evaluated. Methods: Chimeric mAb (cmAb) U36, directed against an antigen preferentially expressed in head and neck cancer, was labeled with 89Zr using the bifunctional chelate N-succinyldesferrioxamine B (N-sucDf) and with 88Y using the bifunctional chelate p-isothiocyanatobenzyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (p-SCN-Bz-DOTA). The radioimmunoconjugates were coinjected in xenograft-bearing nude mice, and biodistribution was determined at 3, 24, 48, 72, and 144 h after injection. 89Zr was evaluated and compared with 18F in phantom studies to determine linearity, resolution, and recovery coefficients, using a high-resolution research tomograph PET scanner. The potential of PET to quantify cmAb U36-N-sucDf-89Zr was evaluated by relating image-derived tumor uptake data (noninvasive method) to 89Zr uptake data derived from excised tumors (invasive method). Results: 89Zr-N-sucDf-labeled and 88Y-p-SCN-Bz-DOTA-labeled cmAb U36 showed a highly similar biodistribution, except for sternum and thighbone at later time points (72 and 144 h after injection). Small differences were found in kidney and liver. Imaging performance of 89Zr approximates that of 18F, whereas millimeter-sized (19{\textendash}154 mg) tumors were visualized in xenograft-bearing mice after injection of cmAb U36-N-sucDf-89Zr. After correction for partial-volume effects, an excellent correlation was found between image-derived 89Zr tumor radioactivity and γ-counter 89Zr values of excised tumors (R2 = 0.79). Conclusion: The similar biodistribution and the favorable imaging characteristics make 89Zr a promising candidate for use as a positron-emitting surrogate for 90Y.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/44/10/1663}, eprint = {https://jnm.snmjournals.org/content/44/10/1663.full.pdf}, journal = {Journal of Nuclear Medicine} }