Abstract 1895: The influence of gemcitabine and its metabolites on cancer cell metabolism.
Authors: Fux Elie , Schiewe Hajo , Moeller Niels , Reszka Regina , Ruiz Nopinger Patricia 
Published: August 2014

The nucleoside analogue gemcitabine is marketed for patients with locally advanced or metastatic adenocarcinoma of the pancreas as single agent and first-line treatment. In addition, it is widely used for the treatment of various carcinomas and approved by the FDA for several combination treatments. However, many patients develop gemcitabine-resistant tumor cells. This phenomenon is of special concern in pancreatic cancers, as these tumors are known to harbor more than 60 different mutations. In addition, gemcitabine is rapidly metabolized upon entry into the cells, leading to the development of drug metabolites (mono-, di-, tri-phosphates, deaminated and subsequently phosphorylated metabolites, etc.) with minimal differences in molecular mass and partly hydrophilic properties. As a result, quantitative analysis - a prerequisite for understanding the metabolism and the mechanism of action - is extremely difficult. This poses enormous challenges for overcoming gemcitabine resistance and for the development of novel active pharmaceutical ingredients addressing other, additional targets in pancreatic and other cancers. Therefore, pharmaceutical companies need more accurate data on how is gemcitabine metabolized, whether various subpopulations of patients react differently to the drug and on which biomarkers associated with drug sensitivity and/or resistances exist.

Here, we report a new LC-MS/MS method development at Metanomics Health that allows for the first time to accurately assess and quantify the entire range of gemcitabine metabolites. The new method works in high-throughput mode analyzing samples from full blood as well as various cells and tissue in respect to their response to gemcitabine and its derivatives. The analytical platform also includes about 90 key energy metabolites from glycolysis and TCA pathways, nucleobases, amino acids, co-enzymes, etc. This comprehensive analysis covering the key metabolites involved in cancer metabolism can be performed from a single sample in one run and in high-throughput mode.

The detection and in-depth analysis of gemcitabine and its metabolites therefore provides an invaluable basis for a better understanding of gemcitabine's self-potentiation mechanisms, its mechanisms of action, as well as mechanisms that lead to the inactivation of gemcitabine or to gemcitabine-mediated activation of treatment resistance. Subsequently, this might support the development of new combination therapies. To determine remaining gemcitabine activity in patients in the long run, metabolite profiling seems a sagacious next step. This approach may support the decision for the appropriate timing of the next treatment dose, which likely contributes to saving costs, reducing side-effects and even slowing down the process of gemcitabine resistance development.

Citation Format: Elie Fux, Hajo Schiewe, Niels Moeller, Regina Reszka, Patricia Ruiz Nopinger. The influence of gemcitabine and its metabolites on cancer cell metabolism. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1895. doi:10.1158/1538-7445.AM2013-1895