Imaging, Diagnosis, Prognosis Predicting IGF-1R Therapy Response in Bone Sarcomas: Immuno-SPECT Imaging with Radiolabeled R1507

Purpose: To investigate whether indium-111–labeled R1507 (In-R1507) immuno-SPECT (single— photon emission computed tomography), a novel noninvasive, in vivo screening method to visualize membranous insulin-like growth factor 1 receptor (IGF-1R) expression and accessibility, can be used to predict IGF-1R treatment (R1507) response in bone sarcomas. Experimental Design: BALB/c nude mice were subcutaneously implanted with IGF-1R–expressing human bone sarcoma xenografts (OS-1, EW-5, and EW-8) which showed high, modest, or no response, respectively, to R1507, a monoclonal antibody targeting the extracellular domain of IGF-1R. An IGF-1R– negative tumor (OS-33), unresponsive to IGF-1R inhibitors, was examined as well. Mice were injected with In-R1507. Biodistribution and immuno-SPECT/computed tomography imaging studies were carried out 1, 3, and 7 days p.i. in mice with OS-1 and EW-5 xenografts and 3 days p.i. in mice with EW-8 and OS-33