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Non-invasive MRS in new anticancer drug development
P Workman1, R J Maxwell, J R Griffiths
1CRC Department of Medical Oncology, University of Glasgow, UK.
Abstract:
In the rational development of anticancer drugs it is important to employ all the available pharmacological information. Early clinical trials provide an opportunity for hypothesis testing. MRS techniques have the potential to provide valuable data on the preclinical and clinical pharmacokinetics and pharmacodynamics of drugs non-invasively. Here we illustrate advantages and pitfalls of MRS using studies of two fluorine-containing cancer drugs: a beta,beta-difluoro analogue of the alkylating agent chlorambucil and a fluorinated derivative of the nitroimidazole misonidazole, Ro 07-0741. Limitations include signal quenching via protein binding and inadequate sensitivity for more potent drugs like beta,beta-difluorochlorambucil; but fluoromisonidazole was shown to accumulate in tumours and shows promise as a chemical probe for tumour hypoxia, detectable by 19F MRS.
Insights
Magnetic Resonance Spectroscopy (MRS) offers non-invasive insights into anticancer drug pharmacokinetics and pharmacodynamics. While sensitive to drug-target interactions, its application requires careful consideration of limitations like signal quenching.
Area of Science:
- Pharmacology and Drug Development
- Medical Imaging and Spectroscopy
Background:
- Rational anticancer drug development necessitates comprehensive pharmacological data.
- Early clinical trials are crucial for hypothesis testing in drug efficacy.
- Non-invasive techniques are valuable for assessing drug behavior in vivo.
Purpose of the Study:
- To illustrate the advantages and limitations of Magnetic Resonance Spectroscopy (MRS) in evaluating anticancer drugs.
- To assess the utility of MRS for pharmacokinetic and pharmacodynamic studies of novel fluorinated anticancer agents.
Main Methods:
- Utilized 19F MRS to study two fluorine-containing anticancer drugs: a difluoro analogue of chlorambucil and fluoromisonidazole (Ro 07-0741).
- Investigated drug accumulation in tumors and potential for detecting tumor hypoxia.
Main Results:
- Identified limitations of MRS, including signal quenching due to protein binding and insufficient sensitivity for highly potent drugs like difluorochlorambucil.
- Demonstrated that fluoromisonidazole accumulates in tumors.
- Fluoromisonidazole shows potential as a chemical probe for detecting tumor hypoxia via 19F MRS.
Conclusions:
- 19F MRS is a valuable tool for non-invasive pharmacokinetic and pharmacodynamic assessment of anticancer drugs.
- Challenges such as signal quenching and sensitivity must be addressed for broader MRS application.
- Fluoromisonidazole shows promise for in vivo tumor hypoxia detection using 19F MRS.