title: Pyruvate sensitizes pancreatic tumors to hypoxia-activated prodrug TH-302.
abstract: BACKGROUND
  Hypoxic niches in solid tumors harbor therapy-resistant cells. Hypoxia-activated prodrugs (HAPs) have been designed to overcome this resistance and, to date, have begun to show clinical efficacy. However, clinical HAPs activity could be improved. In this study, we sought to identify non-pharmacological methods to acutely exacerbate tumor hypoxia to increase TH-302 activity in pancreatic ductal adenocarcinoma (PDAC) tumor models.
  
  
  RESULTS
  Three human PDAC cell lines with varying sensitivity to TH-302 (Hs766t > MiaPaCa-2 > SU.86.86) were used to establish PDAC xenograft models. PDAC cells were metabolically profiled in vitro and in vivo using the Seahorse XF system and hyperpolarized (13)C pyruvate MRI, respectively, in addition to quantitative immunohistochemistry. The effect of exogenous pyruvate on tumor oxygenation was determined using electroparamagnetic resonance (EPR) oxygen imaging. Hs766t and MiaPaCa-2 cells exhibited a glycolytic phenotype in comparison to TH-302 resistant line SU.86.86. Supporting this observation is a higher lactate/pyruvate ratio in Hs766t and MiaPaCa xenografts as observed during hyperpolarized pyruvate MRI studies in vivo. Coincidentally, response to exogenous pyruvate both in vitro (Seahorse oxygen consumption) and in vivo (EPR oxygen imaging) was greatest in Hs766t and MiaPaCa models, possibly due to a higher mitochondrial reserve capacity. Changes in oxygen consumption and in vivo hypoxic status to pyruvate were limited in the SU.86.86 model. Combination therapy of pyruvate plus TH-302 in vivo significantly decreased tumor growth and increased survival in the MiaPaCa model and improved survival in Hs766t tumors.
  
  
  CONCLUSIONS
  Using metabolic profiling, functional imaging, and computational modeling, we show improved TH-302 activity by transiently increasing tumor hypoxia metabolically with exogenous pyruvate. Additionally, this work identified a set of biomarkers that may be used clinically to predict which tumors will be most responsive to pyruvate + TH-302 combination therapy. The results of this study support the concept that acute increases in tumor hypoxia can be beneficial for improving the clinical efficacy of HAPs and can positively impact the future treatment of PDAC and other cancers.
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Jonathan W
authors: JW
authors: Wojtkowiak
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Heather C
authors: HC
authors: Cornnell
authors: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA.
authors: Shingo
authors: S
authors: Matsumoto
authors: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA.
authors: Keita
authors: K
authors: Saito
authors: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA.
authors: Yoichi
authors: Y
authors: Takakusagi
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Prasanta
authors: P
authors: Dutta
authors: Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Munju
authors: M
authors: Kim
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Xiaomeng
authors: X
authors: Zhang
authors: Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, AZ 85724 USA ; Hematology/Oncology Section, College of Medicine, University of Arizona, Tucson, AZ 85724 USA.
authors: Rafael
authors: R
authors: Leos
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Kate M
authors: KM
authors: Bailey
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Gary
authors: G
authors: Martinez
authors: Analytic Microscopy Core Facility, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Mark C
authors: MC
authors: Lloyd
authors: Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, AZ 85724 USA.
authors: Craig
authors: C
authors: Weber
authors: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA.
authors: James B
authors: JB
authors: Mitchell
authors: Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, AZ 85724 USA ; Department of Physiology, College of Medicine, University of Arizona, Tucson, AZ 85724 USA.
authors: Ronald M
authors: RM
authors: Lynch
authors: Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, AZ 85724 USA ; Hematology/Oncology Section, College of Medicine, University of Arizona, Tucson, AZ 85724 USA.
authors: Amanda F
authors: AF
authors: Baker
authors: Department of Radiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA ; Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Robert A
authors: RA
authors: Gatenby
authors: Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA ; Department of Oncologic Sciences, University of South Florida, Tampa, FL 33612 USA.
authors: Katarzyna A
authors: KA
authors: Rejniak
authors: Threshold Pharmaceutical, San Francisco, CA 94080 USA.
authors: Charles
authors: C
authors: Hart
authors: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA.
authors: Murali C
authors: MC
authors: Krishna
authors: Department of Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA ; Department of Radiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612 USA.
authors: Robert J
authors: RJ
authors: Gillies
keywords: Computational modeling; Functional imaging; Hypoxia; Hypoxia-activated prodrugs; Metabolism; Pancreatic cancer; TH-302; Tumor microenvironment
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