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Identification, Characterization, and Suppression of Side Products Formed during the Synthesis of [177Lu]Lu-PSMA-617


Martin, Sebastian; Tönnesmann, Roswitha; Hierlmeier, Ina; Maus, Stephan; Rosar, Florian; Ruf, Juri; Holland, Jason P; Ezziddin, Samer; Bartholomä, Mark D (2021). Identification, Characterization, and Suppression of Side Products Formed during the Synthesis of [177Lu]Lu-PSMA-617. Journal of Medicinal Chemistry, 64(8):4960-4971.

Abstract

In recent years, radiolabeled tracers targeting prostate-specific membrane antigen (PSMA) have had a tremendous impact on prostate cancer management. Here, we report on the formation of radioactive impurities formed during the clinical production of 177Lu-labeled PSMA-617. We provide compelling evidence that these impurities are the result of a spontaneous, thermally mediated condensation reaction of the Glu-CO-Lys moiety resulting in the formation of three different five-membered ring systems. Density functional theory (DFT) calculations show that the condensation and cyclization of the Glu-CO-Lys moiety is thermodynamically spontaneous. In cell experiments, no affinity of these cyclized compounds toward PSMA was observed. HPLC analyses of urine samples from patient studies showed rapid renal excretion of these radioactive cyclized species. Radiolabeling conditions were identified that significantly reduced the formation of cyclized side products yielding 177Lu-labeled PSMA-617 in high radiochemical yield and purity in concordance with current good manufacturing practice (cGMP) requirements.

Abstract

In recent years, radiolabeled tracers targeting prostate-specific membrane antigen (PSMA) have had a tremendous impact on prostate cancer management. Here, we report on the formation of radioactive impurities formed during the clinical production of 177Lu-labeled PSMA-617. We provide compelling evidence that these impurities are the result of a spontaneous, thermally mediated condensation reaction of the Glu-CO-Lys moiety resulting in the formation of three different five-membered ring systems. Density functional theory (DFT) calculations show that the condensation and cyclization of the Glu-CO-Lys moiety is thermodynamically spontaneous. In cell experiments, no affinity of these cyclized compounds toward PSMA was observed. HPLC analyses of urine samples from patient studies showed rapid renal excretion of these radioactive cyclized species. Radiolabeling conditions were identified that significantly reduced the formation of cyclized side products yielding 177Lu-labeled PSMA-617 in high radiochemical yield and purity in concordance with current good manufacturing practice (cGMP) requirements.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:Molecular Medicine, Drug Discovery
Language:English
Date:7 April 2021
Deposited On:27 Apr 2021 09:31
Last Modified:24 Feb 2024 02:50
Publisher:American Chemical Society (ACS)
ISSN:0022-2623
OA Status:Green
Publisher DOI:https://doi.org/10.1021/acs.jmedchem.1c00045
Project Information:
  • : FunderSNSF
  • : Grant IDPP00P2_163683
  • : Project TitleAdvanced radiochemical methods for multi-modal imaging with nanomedicines
  • : FunderSNSF
  • : Grant IDPP00P2_190093
  • : Project TitleRadiochemistry in a Flash: Advanced methods for the synthesis of multi-modal imaging agents
  • Content: Accepted Version