Imaging of tumor acidosis for monitoring response to novel anticancer therapies

Longo Dario Livio Institute of Biostructure and Bioimaging (IBB); National Research Council of Italy (CNR), Torino, Italy.

Imaging based methods are already been established, at clinical level, to assess glucose metabolism (by positron emission tomography - PET imaging of 18F-fluorodeoyglucose FDG tumor uptake) and metabolite levels (by exploiting Magnetic Resonance Spectroscopy Imaging) providing a formidable tool for evaluating treatment response. Conversely, despite the excellent studies regarding tumor acidosis, we still do not have an effective imaging protocol that allow to quantify extracellular tumor pH and to assess tumor pH related changes following therapeutic treatment. Furthermore, new anticancer drugs that target tumor metabolism and acidosis, with the consequent impairment of tumour growth, cannot be evaluated in vivo both at preclinical and clinical level. We have developed innovative MRI-based approaches for assessing in vivo tumor acidosis by using already clinically-used x-ray contrast agents that are translatable to the clinical scenario. We have exploited tumor pH imaging for assessing its relationship with cancer metabolism and metastatic potential as well as for assessing treatment response to novel anticancer therapies.
We will discuss different MRI-based approaches developed for imaging tumor acidosis, using examples from our own research and from recent literature. Based on these data, tumor pH imaging may be a potential innovative diagnostic tool for characterizing tumor metabolism and to evaluate treatment response.

Acknowledgements: Grant from the Associazione Italiana Ricerca Cancro (AIRC MFAG 2017 - ID. 20153 project – P.I. Longo Dario Livio) is kindly acknowledged.