This proposal will continue the development of an innovative MRI method that can measure the extracellular pH (pHe) of the tumor microenvironment. Our MRI method uses Chemical Exchange Saturation Transfer (CEST) agents that accurately and precisely measure pH. We have used our CEST agents and CEST MRI methods to map tumor pHe in mouse tumor models. We propose to improve the detection sensitivity of CEST MRI to facilitate our pre-clinical studies eventual clinical translation. Our research has strong impact because tumor pHe measurements may be used to predict the effects of weak-base and weak-acid chemotherapies before they are administered to a patient. Tumor pHe measurements may also be used to monitor alkalinizing therapies that can increase survival and decrease metastasis. We propose to establish that our CEST MRI method can measure tumor pHe with sufficient accuracy and precision to impact the choice of cancer therapies. ? Specific Aim 1: To improve the detection sensitivity of CEST MRI methods and CEST agents that measure tumor pHe. We will optimize the saturation period of the CEST MRI pulse sequence, and improve our paramagnetic CEST agents to have larger chemical shifts. ? Specific Aim 2: To monitor the effect of alkalinizing therapy using tumor pHe measurements. We hypothesize that monitoring pHe can be used to optimize the dose of an alkalinizing therapy to raise tumor pHe without affecting kidney pHe. ? Specific Aim 3: To quantitatively predict chemotherapeutic effects with tumor pHe measurements. We hypothesize that a single tumor pHe measurement before initiating chemotherapy can quantitatively predict the therapeutic effect on tumor growth. Our deliverable is a clinically-translatable imaging method that can profoundly impact personalized medicine. By quantitatively measuring the acidity of a solid tumor, a physician may then select the weak-base or weak- acid chemotherapy that should have a better therapeutic effect for that individual patient. By monitoring the pHe of the tumor and kidney, a physician may adjust an alkalinizing treatment dosage to provide an optimal therapeutic effect for an individual patient. Although our research focuses on breast cancer, our methodology can impact personalized medicine for many other cancers and other pathologies.

Public Health Relevance

This research project will refine CEST agents and CEST MRI methods that measure extracellular pH (pHe) in pre-clinical tumor models. These methods will be used to optimize the dose of an alkalinizing therapy and to predict the efficacy of weak-base and weak-acid chemotehrapies.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Clinical Molecular Imaging and Probe Development (CMIP)
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Zhang, Huiming
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University of Arizona
Biomedical Engineering
Schools of Engineering
United States
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Randtke, Edward A; Chen, Liu Qi; Pagel, Mark D (2014) The reciprocal linear QUEST analysis method facilitates the measurements of chemical exchange rates with CEST MRI. Contrast Media Mol Imaging 9:252-8
Randtke, Edward A; Chen, Liu Qi; Corrales, L Rene et al. (2014) The Hanes-Woolf linear QUESP method improves the measurements of fast chemical exchange rates with CEST MRI. Magn Reson Med 71:1603-12
Jeffery, Justin J; Lux, Katie; Vogel, John S et al. (2014) Autocrine inhibition of the c-fms proto-oncogene reduces breast cancer bone metastasis assessed with in vivo dual-modality imaging. Exp Biol Med (Maywood) 239:404-13