Radiolabeled Inhibitors for Prostate Cancer Imaging & Therapeutics

Abstract (Set) Prostate-specific membrane antigen (PSMA) is a cell surface protein that is over expressed in prostate cancer, including hormone-refractory and metastatic disease. Successful imaging of xenografts that express the prostate-specific membrane antigen (PSMA) using small animal PET and PSMA inhibitors has led to the investigation of the possibility of utilizing the more economical radionuclide 99mTc for SPECT imaging of prostate cancer. JHU scientist have prepared novel 99mTc/Re chelated compounds by attaching known Tc/Re chelating agents to an amino functionalized PSMA inhibitor using a novel linking group. The affinity of each new ligand and their corresponding rhenium complexes were measured by 3H-NAAADase (N-acetyl-a-linked acid dipeptidase) assay and ranged from 0.2 nM to 20 nM. Biodistribution and imaging (CT-SPECT) showed that all of the novel Tc-99m radiolabeled compounds bind specifically to PSMA-expressing tumor xenografts in mouse models of prostate cancer. Radioactivity cleared from normal organs to give high tumor/organ ratios at later time points. Overall results demonstrate that the PSMA can accommodate the greater steric requirements of 99mTc/Re complexes within PSMA inhibitors and provide the beginnings of a structure-activity relationship of 99mTc/Re labeled PSMA inhibitors. Description (Set) Key Features ? Early diagnosis of prostate and other cancers/ ? Imaging tumor angiogenesis/ ? Better delineation of tumor margins during tumor surgery (real time)/ ? Small molecule delivery of therapeutic radionuclides to prostate and other cancers/ ? Similar imaging agent for use in brain imaging for psychiatric disease Proposed Use (Set) These new long linking group containing Tc-99m based PSMA imaging agents have not been synthesized previously and can be used as Tc-94 based PET imaging as well as Re-188 based therapeutic agents, all of which are small molecules. The novel linking group is a new chemical entity that can further be utilized to attach other metal based imaging agents.

Inventor(s): Pomper, Martin Gilbert ,Foss, Catherine,Mease, Ronnie C.,Ray, Sangeeta

Type of Offer: Licensing



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