Imaginab, Inc. — Department of Health and Human Services SBIR Phase II: Molecularly targeted imaging agents for the detection, staging, and monitoring of prostate

Description

Molecularly targeted imaging agents for the detection, staging, and monitoring of prostate cancer are urgently needed. Prostate Membrane Specific Antigen (PSMA) is a membrane glycoprotein expressed by all prostate cancer. In Phase I of this contract, we reengineered a humanized PSMA-specific antibody to provide a nanoscale biological targeting reagent. Minibodies (~8-10 nm) are significantly smaller than antibodies, yet exhibit dramatically improved properties for in vivo delivery and imaging: full bindingcombined with rapid in vivo kinetics. Following radiolabeling with I-124 or Cu-64, PSMA-specific minibodies demonstrated excellent biodistribution and microPET imaging properties in a preclinical model of prostate cancer. In Phase II we propose to (1) Optimize labeling conditions for the huJ591 minibody using both residualizing and non-residualizing radiolabels and formally compare biodistribution and imaging performance, in order to finalize the radiolabeling strategy for huJ591 minibody use clinically. (2) Perform a scale-down production run and conduct testing and toxicity studies required for regulatory filing. Public health relevance: A novel, nanoscale imaging agent has been developed for the specific detection of prostate cancer in patients with the goal of commercialization. Success of these PSMA-specific minibodies will establish important groundwork for using this class of engineered biomolecules for additional in vivo nanotargeting strategies.