Synthesis and Evaluation of a Radioiodinated Tracer with Specificity for Poly(ADP-ribose) Polymerase‑1 (PARP-1) in Vivo
journal contributionposted on 12.11.2015, 00:00 by Filip Zmuda, Gaurav Malviya, Adele Blair, Marie Boyd, Anthony J. Chalmers, Andrew Sutherland, Sally L. Pimlott
Interest in nuclear imaging of poly(ADP-ribose) polymerase-1 (PARP-1) has grown in recent years due to the ability of PARP-1 to act as a biomarker for glioblastoma and increased clinical use of PARP-1 inhibitors. This study reports the identification of a lead iodinated analog 5 of the clinical PARP-1 inhibitor olaparib as a potential single-photon emission computed tomography (SPECT) imaging agent. Compound 5 was shown to be a potent PARP-1 inhibitor in cell-free and cellular assays, and it exhibited mouse plasma stability but approximately 3-fold greater intrinsic clearance when compared to olaparib. An 123I-labeled version of 5 was generated using solid state halogen exchange methodology. Ex vivo biodistribution studies of [123I]5 in mice bearing subcutaneous glioblastoma xenografts revealed that the tracer had the ability to be retained in tumor tissue and bind to PARP-1 with specificity. These findings support further investigations of [123I]5 as a noninvasive PARP-1 SPECT imaging agent.