A phase I/IIa trial of prostate specific membrane antigen (PSMA) positron emission tomography (PET) imaging with 89Zr-Df-IAB2M in metastatic prostate cancer (PCa).

287 Background: There is a pressing need for improved imaging biomarkers to identify disease distribution and response in both localized and advanced prostate cancer patients. PSMA-directed imaging is undergoing analytic and clinical validation for these contexts of use. IAB2M is an anti-PSMA recombinant minibody (Mb) derived from huJ591. We have previously reported on 28 pts imaged with IAB2M(Pandit-Taskar et al, SNM 2015). Here we report the lesion targeting and uptake (SUV) of the Mb and correlation with pathology of biopsied lesions on the full complement of the 38 pts examined in this trial. Methods: 38 pts with progressive metastatic PCa received escalating amounts of the Mb (16 pts at 10mg, 16 pts at 20mg, 6 pts at 50mg) in a phase I/IIa trial. All pts underwent standard imaging (SI) using CT, bone scintigraphy (BS), FDG PET, followed by imaging with 5 mCi of IAB2M. Whole body PET/CT scans were performed and evaluated for lesion targeting and SUVmax. Biopsy (bx) locations were selected by a consens...