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Quinone oxidoreductase-2-mediated prodrug cancer therapy

Mark R Middleton1, Richard Knox, Emma Cattell

  • 1Department of Medical Oncology, Churchill Hospital, Headington, Oxford OX3 7LJ, UK. mark.middleton@medonc.ox.ac.uk

Science Translational Medicine
|July 16, 2010
PubMed

Insights

This study shows that human quinone oxidoreductase-2 (NQO2) can activate the chemotherapy drug CB1954 using a synthetic cofactor. This activation leads to DNA damage in tumor cells, offering a targeted cancer treatment approach.

Area of Science:

  • Biochemistry
  • Pharmacology
  • Oncology

Background:

  • DNA-damaging agents are crucial in cancer therapy but often lack tumor specificity.
  • Human NQO2 (quinone oxidoreductase-2) is an unusual oxidoreductase with no known endogenous electron donor.
  • NQO2 exhibits significantly higher activity in hepatocellular tumors compared to other cancers and bone marrow.

Purpose of the Study:

  • To investigate the activation of the prodrug CB1954 by human NQO2 using a synthetic nicotinamide cofactor analog, EP0152R.
  • To determine the optimal infusion schedule for a phase I clinical trial based on structural modeling of drug binding.
  • To assess the safety, pharmacokinetics, and efficacy of the CB1954 and EP0152R combination in cancer patients.

Main Methods:

  • Utilized X-ray crystallography and nuclear magnetic resonance spectroscopy to model the binding of CB1954 and EP0152R to NQO2.
  • Conducted a phase I clinical trial with 32 patients to establish the maximum tolerated dose and evaluate drug interactions.
  • Analyzed tumor biopsies to detect DNA interstrand cross-links as a measure of prodrug activation and cytotoxic effect.

Main Results:

  • Structural modeling guided the design of an optimal infusion schedule for the phase I trial.
  • Diarrhea and elevated serum transaminases identified the maximum tolerated dose for the combination therapy.
  • Observed a significant pharmacokinetic interaction where EP0152R increased CB1954 clearance, consistent with model predictions.
  • Confirmed DNA interstrand cross-links in tumor biopsies, validating the mechanism of action through DNA base alkylation by activated CB1954.

Conclusions:

  • The NQO2-mediated activation of CB1954 by EP0152R represents a promising strategy for targeted cancer therapy.
  • The study successfully demonstrated the clinical feasibility and mechanism of action of this novel prodrug activation system.
  • Further clinical development is warranted to explore the therapeutic potential of this approach in NQO2-expressing tumors.

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