Two is better than one: difunctional high-affinity PSMA probes based on a [CpM(CO)3] (M = Re/99mTc) scaffold

Dalton Trans. 2019 Oct 7;48(39):14600-14605. doi: 10.1039/c9dt02506e.

Abstract

More than 10% of all men will be given the diagnosis "prostate cancer" during their lifetime. Most of the current radio-diagnostic vehicles involve both expensive and localized production with cyclotrons as well as the use of bulky chelators for the radiometal. We report the use of a new multifunctional cyclopentadiene (Cp) platform to prepare difunctional and monofunctional, PSMA-targeting rhenium and technetium-99m complexes. The Cp-complexes and the free ligands are prepared by straightforward functionalization with either one or two Lys-urea-Glu (LuG) PSMA binding motifs. Cell binding assays revealed that the difunctional rhenium complex displays a dissociation constant (KD = 2.1 nM) that is an order of magnitude lower than the monofunctional compound (KD = 24.2 nM). The 99mTc complexes can be prepared in one step and ≤15 min in high yields. These difunctional Cp-Re(i)/99mTc(i) complexes represent a new class of imaging agents with binding affinities comparable to clinically evaluated compounds. Additionally, this study demonstrates that the Cp-platform can readily be derivatized with amine-containing biomolecules. Extending this work to incorporate both targeting and therapeutic moieties could lead to theranostic systems with Re/99mTc.

MeSH terms

  • Antigens, Surface / metabolism*
  • Chelating Agents / chemistry*
  • Glutamate Carboxypeptidase II / metabolism*
  • Humans
  • Male
  • Prostatic Neoplasms / diagnosis*
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / metabolism
  • Radiopharmaceuticals / chemistry*
  • Rhenium / chemistry*
  • Technetium / chemistry*
  • Thiazoles / chemistry*
  • Tumor Cells, Cultured

Substances

  • Antigens, Surface
  • Chelating Agents
  • Radiopharmaceuticals
  • Thiazoles
  • Rhenium
  • Technetium
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II
  • 2-phenylbenzothiazole