Abnormal cellular metabolism is a hallmark of cancer, yet there is an absence of quantitative methods to dynamically image this powerful cellular function. Optical metabolic imaging (OMI) is a non-invasive, high-resolution, quantitative tool for monitoring cellular metabolism. OMI probes the fluorescence intensities and lifetimes of the autofluorescent metabolic co-enzymes reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD). We confirm that OMI correlates with cellular glycolytic levels across a panel of human breast cell lines, using standard assays of cellular rates of glucose uptake and lactate secretion (p<0.05, r=0.89). Additionally, OMI resolves differences in the basal metabolic activity of untransformed from malignant breast cells (p<0.05), and between breast cancer sub-types (p<0.05), defined by estrogen receptor (ER) and/or HER2 expression or absence. In vivo OMI is sensitive to metabolic changes induced by inhibition of HER2 with the antibody trastuzumab (Herceptin) in HER2-overexpressing human breast cancer xenografts in mice. This response was confirmed with tumor growth curves and stains for Ki67 and cleaved caspase-3. OMI resolved trastuzumab-induced changes in cellular metabolism in vivo as early as 48 hours post-treatment (p<0.05), while FDG-PET did not resolve any changes with trastuzumab up to 12-days post-treatment (p>0.05). In addition, OMI resolved cellular sub-populations of differing response in vivo that are critical for investigating drug resistance mechanisms. Importantly, OMI endpoints remained unchanged with trastuzumab-treatment in trastuzumab-resistant xenografts (p>0.05). OMI has significant implications for rapid cellular-level assessment of metabolic response to molecular expression and drug action, which would greatly accelerate drug development studies.

There is a need for technologies to predict the efficacy of cancer treatment in individual patients. Here we show that optical metabolic imaging of organoids derived from primary tumors can predict therapeutic response of xenografts and measure anti-tumor drug responses in human-tumor derived organoids. Optical metabolic imaging quantifies the fluorescence intensity and lifetime of NADH and FAD, co-enzymes of metabolism. As early as 24 hours after treatment with clinically relevant anti-cancer drugs, the optical metabolic imaging index of responsive organoids decreased (p<0.001) and was further reduced when effective therapies were combined (p<5×10–6), with no change in drug-resistant organoids. Drug response in xenograft-derived organoids was validated with tumor growth measurements in vivo and stains for proliferation and apoptosis. Heterogeneous cellular responses to drug treatment were also resolved in organoids. Optical metabolic imaging shows potential as a high-throughput screen to test the efficacy of a panel of drugs to select optimal drug combinations.

The function of a T cell depends on its subtype and activation state. Here, we show that the imaging of autofluorescence-lifetime signals from quiescent and activated T cells can be used to Reprints and permissions information is available at www.nature.com/reprints.Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http:// www.nature.com/authors/editorial_policies/license.html#terms

ObjectivesThree-dimensional organoids derived from primary pancreatic ductal adenocarcinomas are an attractive platform for testing potential anticancer drugs on patient-specific tissue. Optical metabolic imaging (OMI) is a novel tool used to assess drug-induced changes in cellular metabolism, and its quantitative end point, the OMI index, is evaluated as a biomarker of drug response in pancreatic cancer organoids.MethodsOptical metabolic imaging is used to assess both malignant cell and fibroblast drug response within primary murine and human pancreatic cancer organoids.ResultsAnticancer drugs induce significant reductions in the OMI index of murine and human pancreatic cancer organoids. Subpopulation analysis of OMI data revealed heterogeneous drug response and elucidated responding and nonresponding cell populations for a 7-day time course. Optical metabolic imaging index significantly correlates with immunofluorescence detection of cell proliferation and cell death.ConclusionsOptical metabolic imaging of primary pancreatic ductal adenocarcinoma organoids is highly sensitive to drug-induced metabolic changes, provides a nondestructive method for monitoring dynamic drug response, and presents a novel platform for patient-specific drug testing and drug development.

BACKGROUND & AIMS A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense desmoplastic reaction (stroma) that impedes drug delivery to the tumor. Attempts to deplete the tumor stroma have resulted in formation of more aggressive tumors. We have identified STAT3 as a biomarker of resistance to cytotoxic and molecularly targeted therapy in PDAC. The purpose of this study is to investigate the effects of targeting STAT3 on the PDAC stroma and on therapeutic resistance. METHODS Activated STAT3 protein expression was determined in human pancreatic tissues and tumor cell lines. In vivo effects of AZD1480, a JAK/STAT3 inhibitor, gemcitabine or the combination were determined in Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) mice and in orthotopic tumor xenografts. Drug delivery was analyzed by MALDI-imaging mass spectrometry. Collagen second harmonic generation (SHG) imaging quantified tumor collagen alignment and density. RESULTS STAT3 activation correlates with decreased survival and advanced tumor stage in patients with PDAC. STAT3 inhibition combined with gemcitabine significantly inhibits tumor growth in both an orthotopic and the PKT mouse model of PDAC. This combined therapy attenuates in vivo expression of SPARC, increases microvessel density and enhances drug delivery to the tumor without depletion of stromal collagen or hyaluronan. Instead, the PDAC tumors demonstrate vascular normalization, remodeling of the tumor stroma and downregulation of cytidine deaminase (Cda). CONCLUSIONS Targeted inhibition of STAT3 combined with gemcitabine enhances in vivo drug delivery and therapeutic response in PDAC. These effects occur through tumor stromal remodeling and downregulation of Cda without depletion of tumor stromal content.