Synthesis and evaluation of [11C]XR9576 to assess the function of drug efflux transporters using PET.

Abstract

OBJECTIVE:

XR9576 (tariquidar) is an anthranilic acid derivative and potent P-glycoprotein (P-gp) inhibitor. XR9576 has undergone phase I and II studies as combined chemotherapy against cancer. XR9576 has been developed as a useful therapeutic agent but not as a PET probe. We therefore developed [(11)C]XR9576 as a PET probe and assessed whether PET studies using [(11)C]XR9576 are a promising approach to assess P-gp function primarily.

METHODS:

We synthesized [(11)C]XR9576 by methylation of 7-O-desmethyl XR9576 with [(11)C]methyl iodide. In in vivo tissue distribution, the effects of co-injection with XR9576 on the uptake of [(11)C]XR9576 in mice were investigated. PET studies using [(11)C]XR9576 were performed in P-gp and/or Bcrp knockout mice as well as in wild-type mice. Metabolites of [(11)C]XR9576 were measured in the brain and plasma of mice.

RESULTS:

[(11)C]XR9576 was successfully synthesized with suitable radioactivity for injection as well as appropriate radiochemical purity and stability. In in vivo tissue distribution, the brain uptake of [(11)C]XR9576 significantly increased about tenfold of control on co-injection with >10 mg/kg of XR9576. In PET studies, the AUC(brain) ([0-60 min]) in P-gp and P-gp/Bcrp knockout mice was 2- and 11-fold higher than that in wild-type mice. [(11)C]XR9576 showed a high metabolic stability (>90% unchanged form) in the brain and plasma of mice 30 min after injection. These results suggest that a tracer amount of [(11)C]XR9576 behave as the P-gp and Bcrp substrate, and the increased brain uptake or AUC(brain) of [(11)C]XR9576 correlates with P-gp and Bcrp functions.

CONCLUSIONS:

PET studies using [(11)C]XR9576 may be a promising approach for evaluating deficiency of the function of drug efflux transporters targeting intracranial diseases and tumors.

• Authors: Kazunori Kawamura, Fujiko Konno, Joji Yui, Tomoteru Yamasaki, Akiko Hatori, Kazuhiko Yanamoto, Hidekatsu Wakizaka, Makoto Takei, Nobuki Nengaki, Toshimitsu Fukumura, Ming-Rong Zhang
• Journal: Annals of nuclear medicine (Ann Nucl Med) Vol. 24 Issue 5 Pg. 403-12 (Jun 2010) ISSN: 1864-6433 [Electronic] Japan
• PMID: 20361276 (Publication Type: Journal Article)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 1
• Carbon Radioisotopes
• Quinolines
• tariquidar

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 1 (metabolism)
• Animals
• Biological Transport (drug effects)
• Brain (drug effects, metabolism)
• Carbon Radioisotopes
• Injections
• Male
• Mice
• Positron-Emission Tomography (methods)
• Quinolines (blood, chemical synthesis, metabolism)