Metabolic changes to host cells with Toxoplasma gondii infection

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90%. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. Here, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring metabolic response over time using non-invasive autofluorescence lifetime imaging of single cells, seahorse metabolic flux analysis, reactive oxygen species (ROS) production, and metabolomics. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H with infection. These findings are consistent with changes in mitochondrial and glycolytic function, decrease of intracellular glucose, fluctuations in lactate and ROS production in infected cells over time. We also examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which similarly showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours. Glucose metabolic flux analysis indicated that these changes are driven by NADH and NADP+ in T. gondii infection. In sum, metabolic changes in host cells with T. gondii infection were similar during full infection, and kiss and spit. Autofluorescence lifetime imaging can non-invasively monitor metabolic changes in host cells over a microbial infection time-course.

Abstract B01: Microphysiological systems as a next-generation precision immunotherapy tool: From patient heterogeneity to memory-like natural killer cells

Immunotherapy is transforming cancer treatment for thousands of patients worldwide. However, treatment response relies on the patients’ immune system, eliciting heterogeneous results. Numerous parameters contribute to immunotherapy response, including tumor-intrinsic factors such as an immunosuppressive microenvironment characterized by nutrient depletion, acidic pH, or waste products; and tumor-extrinsic factors including genetic immunodeficiencies, or immunosuppressive disorders like HIV infection or organ transplant medication. Consequently, predicting response to immunotherapy remains challenging. Thus, we designed a microphysiological system (MPS) that allows us to incorporate these factors to evaluate patient-specific immunotherapy efficacy. We used our MPS to assess memory-like natural killer (mNK) cell efficacy against solid tumors, as well as evaluated NK cell exhaustion in a tumor-induced suppressive environment. Focusing upon head and neck squamous cell carcinoma (HNSCC), we evaluated risk/benefit ratios and mNK cell responses, including mNK cell extravasation; tumor penetration/killing; and synergy with therapeutic antibodies. We observed that the tumor-induced microenvironment led to gradual erosion of natural killer (NK) cells’ cytotoxicity and upregulation of exhaustion markers. Interestingly, NK cells exhibited a limited capacity to recover from tumor-induced exhaustion, and checkpoint inhibitors and immunomodulatory agents (e.g., PD-1, IDO-1 inhibitors) partially prevented NK cell exhaustion. We also infected T cells with HIV to evaluate whether immunocompromised patients would benefit from mNK cell therapy in the same fashion. In this context, mNK cells exhibited promising immunotherapeutic potential for these populations as they retained tumor killing capacity even in the absence of T cells; mNK cells exhibited extravasation and migration towards patient-derived tumor spheroids, suggesting that mNK cells alone are capable of extravasation. However, CD4 T cells enhanced mNK responses and elicited overexpression of NK survival and function-associated genes, suggesting that future guidelines for people living with HIV and cancer should consider the progression of the disease when considering mNK cell-based therapies. Our MPS may also help to identify CD4 T cell-secreted factors with therapeutic potential to increase mNK cell responses, which could be provided ex vivo in immunocompromised patients. In summary, MPSs offer a precision tool to assess treatment responses in a patient-specific fashion and may help identify next-generation immunotherapies for hitherto excluded cohorts.

Citation Format: Catherine A McBain, Mehtab A Farooqui, María Virumbrales-Muñoz, Cristina Sanchez-de-Diego, Sireesh Kumar Teertam, Rebecca Schmitz, Melissa Skala, David J Beebe, Jose M Ayuso. Microphysiological systems as a next-generation precision immunotherapy tool: From patient heterogeneity to memory-like natural killer cells [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr B01.

Abstract 3090: Patient derived cancer organoids predict clinical response for patients with locally advanced rectal cancer

Background: Locally advanced rectal cancer (LARC) is a common disease in the US, with a growing incidence in younger patients. These patients undergo multimodality treatments including chemotherapy, radiation, and surgery. For some patients this is likely over-treatment, while other patients require further treatment escalation. To date there is no clinical tool to know the potential benefit of these individual therapies. Patient-derived cancer organoids (PDCOs) are beginning to be evaluated for use as a means to predict individual patient response to clinical therapies. Here we use PDCOs from patients with LARC to compare the PDCO response to the individual clinical response.

Methods: Fresh LARC tissues from patients undergoing an endoscopy and tattooing procedure were obtained following consent on an IRB-approved protocol. PDCOs were cultured in using Matrigel and our previously published CRC organoids media. Following culture maturation, PDCOs were treated with control media, 5uM 5FU, 10uM Oxaliplatin, Combination (FOLFOX), XRT (2Gy) or 5FU and XRT. Brightfield imaging was performed at baseline and following 96 hours of treatment. Glass’s delta is used as a measure of the organoid treatment effect. A Glass’s delta of 1.25 was used as a threshold of treatment response based on prior studies. Clinical imaging was evaluated using standard RECIST v1.1 criteria of the objective response.

Results: Endoscopic LARC biopsy samples were obtained from 22 patients. 11 of the 22 samples were able to be grown as PDCOs. To date 9 cultures have been treated with FOLFOX and 9 have been treated with 5FU and XRT. For those treated with FOLFOX, 3/9 had a Glass’s delta greater than 1.25 and all of these patients has a clinical partial response (PR). None of those patients’ whose PDCOs did not achieve a Glass’s delta of at least 1.25 had a PR to FOLFOX clinically. No PDCO’s treated with 5FU and XRT achieved a Glass’s delta of >1.25. 3/9 PDCOs had a Glass’s delta >1.0. All of these patients had a PR. Of the 7 patients whose PDCOs did not achieve a Glass’s delta of 1 in response to 5FU and XRT, none had a clinical PR (Glass’s delta range 0.6-0.93).

Conclusion: PDCOs hold great promise as a tool to predict clinical outcomes for patients with LARC. Further evaluations need to establish improved methods of PDCO generation from biopsy samples and confirm the optimum response thresholds for prediction of treatment response.

Citation Format: Shirsa Udgata, Aishwarya Sunil, Rebecca L. Schmitz, Barsha Pantha, Amani Gillette, Jeremy Kratz, Patrick Grogan, Rebecca DeStefanis, Katherine Johnson, Sean Kraus, Evie Carchman, Elise Lawson, Christina Sanger, Charles Heise, Michael Bassetti, Randall Kimple, Kayla Lemmon, Morgan Larson, Cheri Pasch, Melissa Skala, Dustin Deming. Patient derived cancer organoids predict clinical response for patients with locally advanced rectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3090.

43 Intravital multiphoton imaging of infiltrating CD8 T cell and tumor cell metabolism during immunotherapy in a murine melanoma model

Background

Intravital multiphoton microscopy (IMM) provides single cell imaging within intact living systems. IMM of the autofluorescent metabolic co-enzymes NAD(P)H and FAD, optical metabolic imaging (OMI), provides in vivo label-free imaging of metabolic changes. The metabolism of tumor and immune cells is closely associated with cancer progression and tissue site,1–4 so we aim to study metabolic trends during administration of an effective, triple-combination immunotherapy within murine melanoma tumors.5 This therapy includes external beam radiation, intratumoral hu14.18-IL2 immunocytokine (anti-GD2 mAb fused to IL2), and intraperitoneal anti-CTLA-4 leading to in situ vaccination and cure of GD2+ murine tumors.5 Previous work has shown that a T cell response is critical to the efficacy of this therapy,5–6 so we created an mCherry-labeled T cell mouse model to study this response. Here, IMM was used to image concurrent tumor and CD8+ T cell metabolic trends during administration of immunotherapy.

Methods

We created an mCherry-labeled CD8+ T cell mouse model through CRISPR/Cas9 knock-in. We then implanted syngeneic B78 (GD2+) melanoma cells into the flanks of these reporter mice to induce measurable tumors. Mice were anesthetized, skin flap surgery performed, and tumors imaged at several time points. IMM was performed using 750–1040 nm to excite NAD(P)H, FAD, and mCherry through a 40X (1.15 NA) objective. Fluorescence lifetime data was collected using time correlated single photon counting electronics. Murine tissues were harvested and analyzed via flow cytometry and multiplex immunofluorescence to corroborate IMM findings and characterize the immune infiltrate.

Results

Here we demonstrate the feasibility of our IMM platform to capture single cell metabolic changes during immunotherapy administration. Through our intravital imaging we show that CD8 T cell and tumor cell redox ratio (intensity of NAD(P)H/intensity of NAD(P)H + FAD) is significantly increased in treated compared to control mice (figure 1), possibly indicating increased glycolytic activity. We also show differences in protein binding within both CD8 T cells and tumor cells during treatment. Overall, this technology enables analysis of metabolic changes in CD8 T cells and tumor cells in vivo during administration of our immunotherapy regimen.

Abstract 43 Figure 1

In vivo multiphoton images of immune and tumor cell populations during immunotherapy. A) Representative in vivo fluorescence intensity images of B78 melanoma tumors growing in control and treated CD8 mCherry reporter mice show mCherry-labeled CD8+ T cells (red) infiltrating tumor tissue as well as autofluorescent metabolic coenzymes NAD(P)H (blue) and FAD (green) expressed by the tumor and T cells. Scale bar 25 μm. B) Corresponding in vivo optical redox ratio intensity images show redox balance within the tumor microenvironment. Treated tumors exhibit an increased optical redox ratio which may indicate increased glycolytic activity during immunotherapy. C) Quantified single-cell B78 tumor (n = 353) and CD8 T cell (n = 18) autofluorescence data. Both CD8 T cells (p<0.0001) and tumor cells (p<0.0034) exhibit significantly increased optical redox ratio with treatment (n = 2 mice, median – center bold dashed line, 3rd quartile – upper dashed line, 1st quartile – lower dashed line, Mann-Whitney U Test).

Conclusions

These results provide additional support that the combination of intravital imaging with OMI allows for concurrent imaging of T cell infiltration and metabolic trends. Specifically, OMI enabled us to probe single cell metabolic changes occurring during our immunotherapy regimen. With continued work, this imaging platform may be leveraged to develop new combinations of immunotherapies.

Acknowledgements

This work is supported by the Morgridge Institute for Research (Interdisciplinary Fellowship awarded to A.R.H.) and the NIH (R01 CA205101 and R35 CA197078). The authors thank the University of Wisconsin Carbone Cancer Center (UWCCC) Support Grant P30 CA014520, the UWCCC Translational Research Initiatives in Pathology laboratory - supported by the UW Department of Pathology and Laboratory Medicine and the Office of The Director NIH (S10OD023526), the UWCCC Flow Cytometry Laboratory, and the Genome Editing and Animal Models Laboratory for core services. The authors also thank Tiffany M. Heaster for training and thoughtful discussions as well as Dan Pham for cell isolation help.

References

Renner K, Singer K, Koehl GE, Geissler EK, Peter K, Siska P J, Kreutz M. Metabolic Hallmarks of Tumor and Immune Cells in the Tumor Microenvironment. Front Immunol 2017, 8 Mar: 1–11.

Mockler MB, Conroy MJ, Lysaght J. Targeting T Cell Immunometabolism for Cancer Immunotherapy; Understanding the Impact of the Tumor Microenvironment. Front Oncol 2014, 4 May: 1–11.

Ghesquière B, Wong BW, Kuchnio A, Carmeliet P. Metabolism of stromal and immune cells in health and disease. Nature 2014; 511(7508):167–176.

Heaster TM, Heaton AR, Sondel PM, Skala MC. Intravital metabolic autofluorescence imaging captures macrophage heterogeneity across normal and cancerous tissue. Front Bioeng Biotechnol 2021, 9(April): 1–10.

Morris ZS, Guy EI, Francis DM, Gressett MM, Werner LR, Carmichael LL, Yang RK, Armstrong EA, Huang S, Navid F, Gillies SD, Korman A, Hank JA, Rakhmilevich AL, Harari PM, Sondel PM. In situ tumor vaccination by combining local radiation and tumor-specific antibody or immunocytokine treatments. Cancer Res 2016; 76 (13): 3929–3941.

Morris ZS, Guy EI, Werner LR, Carlson PM, Heinze CM, Kler JS, Busche SM, Jaquish AA, Sriramaneni RN, Carmichael LL, Loibner H, Gillies SD, Korman AJ, Erbe AK, Hank JA, Rakhmilevich AL, Harari PM, Sondel PM. Tumor-specific inhibition of in situ vaccination by distant untreated tumor sites. Cancer Immunol Res 2018; 6(7): 825–834.

Ethics Approval

All animal work was approved by the University of Wisconsin Institutional Animal Care and Use Committees.

Visualizing Cancer

Imaging has had a profound impact on our ability to understand and treat cancer. We invited some experts to discuss imaging approaches that can be used in various aspects of cancer research, from investigating the complexity and diversity of cancer cells and their environments to guiding clinical decision-making.

Metabolomics revealed the influence of breast cancer on lymphatic endothelial cell metabolism, metabolic crosstalk, and lymphangiogenic signaling in co-culture

Breast cancer metastasis occurs via blood and lymphatic vessels. Breast cancer cells 'educate' lymphatic endothelial cells (LECs) to support tumor vascularization and growth. However, despite known metabolic alterations in breast cancer, it remains unclear how lymphatic endothelial cell metabolism is altered in the tumor microenvironment and its effect in lymphangiogenic signaling in LECs. We analyzed metabolites inside LECs in co-culture with MCF-7, MDA-MB-231, and SK-BR-3 breast cancer cell lines using [Formula: see text] nuclear magnetic resonance (NMR) metabolomics, Seahorse, and the spatial distribution of metabolic co-enzymes using optical redox ratio imaging to describe breast cancer-LEC metabolic crosstalk. LECs co-cultured with breast cancer cells exhibited cell-line dependent altered metabolic profiles, including significant changes in lactate concentration in breast cancer co-culture. Cell metabolic phenotype analysis using Seahorse showed LECs in co-culture exhibited reduced mitochondrial respiration, increased reliance on glycolysis and reduced metabolic flexibility. Optical redox ratio measurements revealed reduced NAD(P)H levels in LECs potentially due to increased NAD(P)H utilization to maintain redox homeostasis. [Formula: see text]-labeled glucose experiments did not reveal lactate shuttling into LECs from breast cancer cells, yet showed other [Formula: see text] signals in LECs suggesting internalized metabolites and metabolic exchange between the two cell types. We also determined that breast cancer co-culture stimulated lymphangiogenic signaling in LECs, yet activation was not stimulated by lactate alone. Increased lymphangiogenic signaling suggests paracrine signaling between LECs and breast cancer cells which could have a pro-metastatic role.

Abstract 4993: Label-free metabolic imaging of T cell response to the tumor microenvironment

Numerous factors including low pH, low glucose, and high lactic acid levels in tumors create an immunosuppressive tumor microenvironment. This immunosuppression is partially due to the metabolic requirements of T cell activation, which are difficult to meet in the tumor microenvironment. The goal of this study is to use label-free optical metabolic imaging (OMI) of the metabolic co-factors NAD(P)H and FAD in CD3-conjugated (activated) and control T cells to monitor metabolic changes of T cells within tumor micro environmental conditions. Single-cell measurements include the optical redox ratio (fluorescence intensity of NAD(P)H divided by FAD), which measures the oxidation-reduction state of the cell, and the mean fluorescence lifetimes (τm) of NAD(P)H and FAD, which measure enzyme-binding activity in the cell. Jurkat T cells were conjugated with CD3 antibody over a two-day incubation period to achieve activation. Control and CD3-conjugated cells were exposed to environments with increasing concentrations of lactic acid (0-20 mM), hydrochloric acid (HCl; pH 6.4- 7.4), and glucose deprivation to mimic the tumor microenvironment. OMI monitored metabolic changes on a single-cell level without confounding factors associated with cell surface marker labeling. Treatment with lactic acid resulted in a significant dose-dependent decrease in the FAD τm and optical redox ratio (p&lt;0.005). Along with changes in metabolism, OMI also resolved impaired mobility of the T cells with increasing lactic acid concentrations. Lactic acid affects both pH and metabolism, so cells were separately exposed to different concentrations of HCl (pH 6.4 - pH 7.4) to monitor pH effects alone. In control cells, the optical redox ratio decreased with decreasing pH (p&lt;0.005). Conversely, in the presence of CD3, the optical redox ratio increased with decreasing pH (p&lt;0.005). CD3 conjugation in glucose deprived environments also resulted in increases in both optical redox ratio and NAD(P)H τm. Cellular viability assays indicate apoptosis only in the lowest pH environment (pH 6.4, p&lt;0.005). These studies indicate that OMI is a promising label-free approach to investigate the effects of the tumor microenvironment on T cell metabolism, activation, and drug response.

Citation Format: Ava VanDommelen, Amani Gillette, Manish S. Patankar, Melissa Skala. Label-free metabolic imaging of T cell response to the tumor microenvironment [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4993.

Abstract 2782: Neuroendocrine tumor spheroid growth and drug response assessment using optical metabolic imaging

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are the second most common form of gastrointestinal cancer, and account for roughly 60% of all neuroendocrine tumors. Unfortunately, no animal models or cell lines exist that reflect the in vivo characteristics of human GEP-NETs. Specifically, human GEP-NETs have low proliferation rates that animal models and cell lines fail to capture. Therefore, drug testing for GEP-NETs often begins in patients without rigorous pre-clinical validation. There is a need to predict the most effective treatments prior to clinical trials for GEP-NET patients, to increase treatment efficacy and reduce toxicities.

Here we show that a three-dimensional spheroid model of primary GEP-NET patient tumors is representative of the original patient tumors including histological features and markers of proliferation (Ki67). Furthermore, this study uses the spheroid model to test a novel drug combination on GEP-NET spheroids, specifically ABT263, a Bcl-2 family inhibitor, and everolimus, a standard GEP-NET treatment that inhibits mTOR. Previous studies have shown that ABT263 induces apoptosis in cancer cells when used in combination with everolimus, making this a promising drug combination for GEP-NET patients. Treatment response to ABT263, everolimus, and the combination, was tested in three-dimensional spheroids derived from seven primary GEP-NET patients, using two-photon optical metabolic imaging (OMI). OMI captures the fluorescence lifetime (τm) and intensity of metabolic cofactors NAD(P)H and FAD. These metrics can be combined into a single number, the OMI index, which was developed to separate responsive and non-responsive cells. The OMI index is the linear combination of the norm-centered redox ratio (NAD(P)H intensity / FAD intensity) + NAD(P)H τm - FAD τm. The OMI index also provides single cell response information from intact spheroids, so that heterogeneity in response can be quantified. Altogether, two-photon OMI in primary patient GEP-NET spheroids provides a novel tool to measure metabolic response to drug treatment.

At 72 hours post-treatment, all patients except two showed a decrease in OMI index, corresponding with a response, to the combination treatment. Heterogeneous response was resolved with two distinct subpopulations of cell metabolism in one of the nonresponsive patients. No changes in spheroid diameter were observed with any treatment, due to the slow growth rate of the GEP-NET tumors and spheroids, further highlighting a need for molecular measures of drug response in these samples. We have shown that representative GEP-NET models can be generated in patient-derived tumor spheroids. Additionally, ABT263 plus everolimus is a promising combination treatment for GEP-NETs. Overall, this work shows that patient-derived tumor spheroids can be established from GEP-NETs, and that OMI provides single-cell metabolic measurements of drug response to guide drug development for patients.

Citation Format: Amani Gillette, Christopher Babiarz, Cheri Pasch, Dustin Deming, Melissa Skala. Neuroendocrine tumor spheroid growth and drug response assessment using optical metabolic imaging [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2782.

Derivation of adult canine intestinal organoids for translational research in gastroenterology

Background

Large animal models, such as the dog, are increasingly being used for studying diseases including gastrointestinal (GI) disorders. Dogs share similar environmental, genomic, anatomical, and intestinal physiologic features with humans. To bridge the gap between commonly used animal models, such as rodents, and humans, and expand the translational potential of the dog model, we developed a three-dimensional (3D) canine GI organoid (enteroid and colonoid) system. Organoids have recently gained interest in translational research as this model system better recapitulates the physiological and molecular features of the tissue environment in comparison with two-dimensional cultures.

Results

Organoids were derived from tissue of more than 40 healthy dogs and dogs with GI conditions, including inflammatory bowel disease (IBD) and intestinal carcinomas. Adult intestinal stem cells (ISC) were isolated from whole jejunal tissue as well as endoscopically obtained duodenal, ileal, and colonic biopsy samples using an optimized culture protocol. Intestinal organoids were comprehensively characterized using histology, immunohistochemistry, RNA in situ hybridization, and transmission electron microscopy, to determine the extent to which they recapitulated the in vivo tissue characteristics. Physiological relevance of the enteroid system was defined using functional assays such as optical metabolic imaging (OMI), the cystic fibrosis transmembrane conductance regulator (CFTR) function assay, and Exosome-Like Vesicles (EV) uptake assay, as a basis for wider applications of this technology in basic, preclinical and translational GI research. We have furthermore created a collection of cryopreserved organoids to facilitate future research.

Conclusions

We establish the canine GI organoid systems as a model to study naturally occurring intestinal diseases in dogs and humans, and that can be used for toxicology studies, for analysis of host-pathogen interactions, and for other translational applications.

Electronic supplementary material

The online version of this article (10.1186/s12915-019-0652-6) contains supplementary material, which is available to authorized users.

Abstract 3472: Dual PI3K/mTOR inhibition in PIK3CA mutant pancreatic cancers

Background: Pancreatic cancer is one of the most deadly cancer diagnoses with limited long-term survival for patients, even with early-stage disease. 3-5% of these cancers have mutations in the phosphoinositide 3-kinase (PI3K) signaling pathway. There is growing interest in targeting cancers with this mutation using specific pathway inhibitors. We have previously proven that dual PI3K/mTOR inhibition is sufficient to decrease tumor growth in mice with a PI3K p110* transgene. Here we aim to determine if this treatment can induce a response in pancreatic cancers with the human PIK3CA H1047R hotspot mutation.

Methods: Transgenic mice were developed using a cre lox-p system (Pdx1-cre) to develop PIK3CA H1047R (PCPK mice) pancreatic adenocarcinomas. Tumors were harvested and grown in spheroid culture. These were treated with increasing concentrations of BEZ235, a dual PI3K/mTOR inhibitor. Treatment groups were compared using spheroid diameter changes and metabolic activity via NADH and FAD+ quantitation. Additionally, immunofluorescence staining was performed and quantified on treated spheroid cultures. PET/CT diagnostics were performed and analyzed pre- and post- treatment with BEZ-235 on a cohort of these experimental mice. Treated tissues were resected for immunohistochemistry and Western blot analyses.

Results: Organotypic PCPK spheroid cultures were treated with BEZ235 in the culture media for 48 hours. Pre- and post-brightfield imaging demonstrated a modest reduction in the percent change in spheroid diameter compared to control (control: 41.8%, BEZ235 100nM: 9%, BEZ235 200nM: -7.7%, BEZ235 400nM: -14.3%; p&lt;0.001). This stability of the spheroid size correlated with minimal differences between the control and treated spheroids using the optical metabolic imaging, including nonsignificant changes in NADH lifetime, FAD+ lifetime and the optical redox ratio (p=NS). PCPK mice (n=10) aged until they developed cancers and then were treated with BEZ235 for 14 days. Pre- and post-positron emission tomography/computed tomography (PET/CT) were performed. Nonsignificant changes in tumor volume and PET avidity were seen between the treatment groups. Both in vitro and in vivo treatments with BEZ235 proved to have no significant change in tumor avidity in this model. Immunoblotting demonstrated persistent activation of the PI3K pathway despite BEZ235 treatment in these spheres and mice as measured by persistent phosphorylation of RPS6 and 4EBP1.

Conclusions: Despite significant responses being previously detected in mice with pancreatic tumors initiated by the PI3K p110* transgene, BEZ235 did not result in a similar treatment effect in PCPK mice possessing the human PIK3CA H1047R hotspot mutation. Further studies will examine the potential resistance mechanisms of these tumors to this therapy and potential ways in which to overcome this resistance.

Citation Format: Susan Payne, Mitchell Depke, Alex Yueh, Joseph T. Sharick, Peter F. Favreau, Cheri A. Pasch, Linda Clipson, Kristina A. Matkowskyj, Melissa Skala, Dustin A. Deming. Dual PI3K/mTOR inhibition in PIK3CA mutant pancreatic cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3472.

Porcine liver vascular bed in Biodur E20 corrosion casts

BACKGROUND

Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting.

MATERIALS AND METHODS

Mercox II® (Ladd Research, Williston, Vermont, USA) and Biodur E20® Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy.

RESULTS

For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20® epoxy resin.

CONCLUSIONS

Only Biodur E20®Plus appeared to be suitable for high-volume vascular corrosion casting due to its optimal permeability, sufficient processing time and minimum fragility. Biodur E20® Plus is slightly elastic, radio-opaque and alcohol-resistant. These properties make this acrylic resin suitable for not only vascular research but also teaching purposes.

Multiphoton redox ratio imaging for metabolic monitoring in vivo

Metabolic monitoring at the cellular level in live tissues is important for understanding cell function, disease processes, and potential therapies. Multiphoton imaging of the relative amounts of NADH and FAD (the primary electron donor and acceptor, respectively, in the electron transport chain) provides a noninvasive method for monitoring cellular metabolic activity with high resolution in three dimensions in vivo. NADH and FAD are endogenous tissue fluorophores, and thus this method does not require exogenous stains or tissue excision. We describe the principles and protocols of multiphoton redox ratio imaging in vivo.

Australia-wide comparison of intensity modulated radiation therapy prostate plans*

The aim of this study was to investigate the ability of Australian centres to produce high-dose intensity modulated radiation therapy (IMRT) prostate plans, and to compare the planning parameters and resultant dose distributions. Five Australian radiation therapy departments were invited to participate. Each centre received an identical 5 mm-slice CT data set complete with contours of the prostate, seminal vesicles, rectum, bladder, femoral heads and body outline. The planning team was asked to produce the best plan possible, using published Memorial Sloan-Kettering Cancer Centre prescription and dose constraints. Three centres submitted plans for evaluation. All plans covered the planning target volume adequately; however, only one plan met all the critical organ dose constraints. Although the planning parameters, beam arrangements and planning systems were different for each centre, the resulting plans were similar. In Australia, IMRT for prostate cancer is in the early stages of implementation, with routine use limited to a few centres.

Radiation therapy for high-risk prostate cancer--a review

The term high-risk prostate cancer has been coined to encompass a group of patients with a poor prognosis (clinical stage T3/T4, or T1/T2 with PSA > 20 ng/ml or GS > 8). It is estimated that 20% of patients in Canada present with high-risk disease, which translates into approximately 4000 new cases each year. The optimal management approach is unclear but the standard of care in North America for this group of patients is radiation therapy (RT) with prolonged adjuvant hormonal therapy. Current clinical trials are evaluating the role of local therapy, the value of RT dose escalation, the potential benefit of regional lymph node irradiation, the appropriate duration of adjuvant hormonal therapy, as well as the possible impact of adjunctive chemotherapy. The high-risk group of patients contains a wide spectrum of disease, ranging from patients with aggressive localized disease to those with widespread occult distant metastases. The current challenge facing clinicians is appropriate treatment selection for individual patients. Information from novel biomarkers and improved imaging, as well as more effective local and adjunctive systemic therapies is necessary to improve outcomes for men with this aggressive disease.

Australian and New Zealand three-dimensional conformal radiation therapy consensus guidelines for prostate cancer

Three-dimensional conformal radiation therapy (3DCRT) has been shown to reduce normal tissue toxicity and allow dose escalation in the curative treatment of prostate cancer. The Faculty of Radiation Oncology Genito-Urinary Group initiated a consensus process to generate evidence-based guidelines for the safe and effective implementation of 3DCRT. All radiation oncology departments in Australia and New Zealand were invited to complete a survey of their prostate practice and to send representatives to a consensus workshop. After a review of the evidence, key issues were identified and debated. If agreement was not reached, working parties were formed to make recommendations. Draft guidelines were circulated to workshop participants for approval prior to publication. Where possible, evidence-based recommendations have been made with regard to patient selection, risk stratification, simulation, planning, treatment delivery and toxicity reporting. This is the first time a group of radiation therapists, physicists and oncologists representing professional radiotherapy practice across Australia and New Zealand have worked together to develop best-practice guidelines. These guidelines should serve as a baseline for prospective clinical trials, outcome research and quality assurance.

[The Czech experience in peritonectomy and hyperthermic perioperative cytostatic lavage in the treatment of peritoneal malignancy]

Peritoneal tumor dissemination has been considered as an incurable condition with fatal outcome. However cytoreductive surgery followed immediately by hyperthermic chemoperfusion has been described both for the treatment and prevention of locoregional cancer spread from various origins. This paper summarizes our experience in this field.

PATIENTS AND METHODS

28 patients were operated on for peritoneal dissemination of malignant tumors between 1999 and 2002 in the Surgical Department of the University Hospital Bulovka. Total or limited peritonectomy was carried out in these patients. In addition intraperitoneal perioperative hyperthermic chemoperfusion was performed using an electrolyte solution containing Mitomycin C, Cisplatin or Carboplatin. The perfusion was performed for 90 minutes, reaching a real hyperthermia of 41 to 43 degrees C.

RESULTS

The overall morbidity was high (85.7%), the perioperative mortality (30 days) was 10.7%. Only 3 (15.7%) of 19 patients in whom complete peritonectomy could be carried out died during the follow-up period of 3 months to 3.5 years.

CONCLUSION

There is an increasing evidence of both experimental and clinical studies showing the therapeutic and prophylactic usefulness of peritonectomy and perioperative hyperthermic chemoperfusion in patients with peritoneal carcinomatosis. However, well designed randomised trials are necessary to establish the role of this promising technique.

Escherichia coli O157:H7 restriction pattern recognition by artificial neural network

An artificial neural network model for the recognition of Escherichia coli O157:H7 restriction patterns was designed. In the training phase, images of two classes of E. coli isolates (O157:H7 and non-O157:H7) were digitized and transmitted to the neural network. The system was then tested for recognition of images not included in the training set. Promising results were achieved with the designed network configuration, providing a basis for further study. This application of a new generation of computation technology serves as an example of its usefulness in microbiology.