ImmunoPET compared with conventional imaging modalities for the detection of Ewing sarcoma metastases in a preclinical model.

10048 Background: Ewing sarcoma is a solid tumor arising from bone and the soft tissues that affects approximately 250 children and adolescents each year. Localized disease confers a favorable 75% 5-year survival, but the prognosis for metastatic disease remains dismal with only a 20% 5-year survival. The ability to accurately diagnose disease extent is therefore crucial. Conventional imaging modalities provide high-resolution anatomic data but lack specificity. The goal of this preclinical study was to compare the detection of metastatic Ewing sarcoma using a 89Zr-labeled anti-CD99 antibody (Ab) with conventional imaging modalities including MRI and [18F]FDG-PET. Methods: NOD scid gamma mice were injected via tail vein with luciferase-transduced TC32 Ewing sarcoma cells and monitored for tumor growth by bioluminescence imaging until development of 2-3 mm liver metastases at 4 weeks. Disease burden and lesion distribution were assessed by MRI and [18F]FDG-PET. Mice were then injected with the 89Zr-labeled...