Synthesis and Evaluation of a Radioiodinated Tracer with Specificity for Poly(ADP-ribose) Polymerase-1 (PARP-1) in Vivo

J Med Chem. 2015 Nov 12;58(21):8683-93. doi: 10.1021/acs.jmedchem.5b01324. Epub 2015 Oct 27.

Abstract

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 (123)I-labeled version of 5 was generated using solid state halogen exchange methodology. Ex vivo biodistribution studies of [(123)I]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 [(123)I]5 as a noninvasive PARP-1 SPECT imaging agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / pharmacokinetics
  • Glioblastoma / diagnosis*
  • Glioblastoma / metabolism
  • Humans
  • Iodine Radioisotopes / chemistry*
  • Iodine Radioisotopes / pharmacokinetics
  • Mice
  • Mice, Nude
  • Phthalazines / chemistry*
  • Phthalazines / pharmacokinetics
  • Piperazines / chemistry*
  • Piperazines / pharmacokinetics
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerase Inhibitors / chemistry*
  • Poly(ADP-ribose) Polymerase Inhibitors / pharmacokinetics
  • Poly(ADP-ribose) Polymerases / analysis*
  • Poly(ADP-ribose) Polymerases / metabolism
  • Tissue Distribution
  • Tomography, Emission-Computed, Single-Photon / methods*

Substances

  • Enzyme Inhibitors
  • Iodine Radioisotopes
  • Phthalazines
  • Piperazines
  • Poly(ADP-ribose) Polymerase Inhibitors
  • PARP1 protein, human
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases
  • olaparib