Distinct Capabilities in NAD Metabolism Mediate Resistance to NAMPT Inhibition in Glioblastoma.

Glioblastoma (GBM) cells require high levels of nicotinamide adenine dinucleotide (NAD) to fuel metabolic reactions, regulate their cell cycle and support DNA repair in response to chemotherapy and radiation. Inhibition of a key enzyme in NAD biosynthesis, NAMPT, has demonstrated significant anti-neoplastic activity. Here, we sought to characterise NAD biosynthetic pathways in GBM to determine resistance mechanisms to NAD inhibitors. GBM cells were treated with the NAMPT inhibitor FK866 with and without NAD precursors, and were analysed by qPCR, Western blot and proliferation assays (monolayer and spheroid). We also measured changes in the cell cycle, apoptosis, NAD/NADH levels and energy production. We performed orthoptic xenograft experiments in athymic nude mice to test the efficacy of FK866 in combination with temozolomide (TMZ). We show that the expression of key genes involved in NAD biosynthesis is highly variable across GBM tumours. FK866 inhibits proliferation, reduces NAD levels and limits oxidative metabolism, leading to G2/M cell cycle arrest; however, this can be reversed by supplementation with specific NAD precursors. Furthermore, FK866 potentiates the effects of radiation and TMZ in vitro and in vivo. NAMPT inhibitors should be considered for the treatment of GBM, with patients stratified based on their expression of key enzymes in other NAD biosynthetic pathways.

Inhibition of the angiotensin II type 2 receptor AT2R is a novel therapeutic strategy for glioblastoma.

Glioblastoma (GBM) is an aggressive malignant primary brain tumor with limited therapeutic options. We show that the angiotensin II (AngII) type 2 receptor (AT2R) is a therapeutic target for GBM and that AngII, endogenously produced in GBM cells, promotes proliferation through AT2R. We repurposed EMA401, an AT2R antagonist originally developed as a peripherally restricted analgesic, for GBM and showed that it inhibits the proliferation of AT2R-expressing GBM spheroids and blocks their invasiveness and angiogenic capacity. The crystal structure of AT2R bound to EMA401 was determined and revealed the receptor to be in an active-like conformation with helix-VIII blocking G-protein or ß-arrestin recruitment. The architecture and interactions of EMA401 in AT2R differ drastically from complexes of AT2R with other relevant compounds. To enhance central nervous system (CNS) penetration of EMA401, we exploited the crystal structure to design an angiopep-2-tethered EMA401 derivative, A3E. A3E exhibited enhanced CNS penetration, leading to reduced tumor volume, inhibition of proliferation, and increased levels of apoptosis in an orthotopic xenograft model of GBM.

Arginine deprivation alters microglial polarity and synergizes with radiation to eradicate non-arginine-auxotrophic glioblastoma tumors.

New approaches for the management of glioblastoma (GBM) are an urgent and unmet clinical need. Here, we illustrate that the efficacy of radiotherapy for GBM is strikingly potentiated by concomitant therapy with the arginine-depleting agent ADI-PEG20 in a non-arginine-auxotrophic cellular background (argininosuccinate synthetase 1 positive). Moreover, this combination led to durable and complete radiological and pathological response, with extended disease-free survival in an orthotopic immune-competent model of GBM, with no significant toxicity. ADI-PEG20 not only enhanced the cellular sensitivity of argininosuccinate synthetase 1-positive GBM to ionizing radiation by elevated production of nitric oxide (˙NO) and hence generation of cytotoxic peroxynitrites, but also promoted glioma-associated macrophage/microglial infiltration into tumors and turned their classical antiinflammatory (protumor) phenotype into a proinflammatory (antitumor) phenotype. Our results provide an effective, well-tolerated, and simple strategy to improve GBM treatment that merits consideration for early evaluation in clinical trials.

Encapsulation of Temozolomide in a Calixarene Nanocapsule Improves Its Stability and Enhances Its Therapeutic Efficacy against Glioblastoma.

The alkylating agent temozolomide (TMZ) is the first-line chemotherapeutic for glioblastoma (GBM), a common and aggressive primary brain tumor in adults. However, its poor stability and unfavorable pharmacokinetic profile limit its clinical efficacy. There is an unmet need to tailor the therapeutic window of TMZ, either through complex derivatization or by utilizing pharmaceutical excipients. To enhance stability and aqueous solubility, we encapsulated TMZ in a p-sulphonatocalix[4]arene (Calix) nanocapsule and used 1H-NMR, LC-MS, and UV-Vis spectroscopy to chart the stability of this novel TMZ@Calix complex according to FDA and European Medicines Agency guidelines. LC-MS/MS plasma stability assays were conducted in mice to further explore the stability profile of TMZ@Calix in vivo The therapeutic efficacy of TMZ@Calix was compared with that of unbound TMZ in GBM cell lines and patient-derived primary cells with known O6-methylguanine-DNA methyltransferase (MGMT) expression status and in vivo in an intracranial U87 xenograft mouse model. Encapsulation significantly enhanced the stability of TMZ in all conditions tested. TMZ@Calix was more potent than native TMZ at inhibiting the growth of established GBM cell lines and patient-derived primary lines expressing MGMT and highly resistant to TMZ. In vivo, native TMZ was rapidly degraded in mouse plasma, whereas the stability of TMZ@Calix was enhanced threefold with increased therapeutic efficacy in an orthotopic model. In the absence of new effective therapies, this novel formulation is of clinical importance, serving as an inexpensive and highly efficient treatment that could be made readily available to patients with GBM and warrants further preclinical and clinical evaluation.

Correction to: Metabolomic profiling identifies distinct phenotypes for ASS1 positive and negative GBM.

In the original publication of this article [1], published on 8 February 2018, it was noticed that the acknowledgement of the source of the drug ADI-PEG20 was missing.

Metabolomic profiling identifies distinct phenotypes for ASS1 positive and negative GBM.

BACKGROUND: Tumour cells have a high demand for arginine. However, a subset of glioblastomas has a defect in the arginine biosynthetic pathway due to epigenetic silencing of the rate limiting enzyme argininosuccinate synthetase (ASS1). These tumours are auxotrophic for arginine and susceptible to the arginine degrading enzyme, pegylated arginine deiminase (ADI-PEG20). Moreover, ASS1 deficient GBM have a worse prognosis compared to ASS1 positive tumours. Since altered tumour metabolism is one of the hallmarks of cancer we were interested to determine if these two subtypes exhibited different metabolic profiles that could allow for their non-invasive detection as well as unveil additional novel therapeutic opportunities. METHODS: We looked for basal metabolic differences using one and two-dimensional gas chromatography-time-of-flight mass spectrometry (1D/2D GC-TOFMS) followed by targeted analysis of 29 amino acids using liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS). We also looked for differences upon arginine deprivation in a single ASS1 negative and positive cell line (SNB19 and U87 respectively). The acquired data was evaluated by chemometric based bioinformatic methods. RESULTS: Orthogonal partial least squares-discriminant analysis (OPLS-DA) of both the 1D and 2D GC-TOFMS data revealed significant systematic difference in metabolites between the two subgroups with ASS1 positive cells generally exhibiting an overall elevation of identified metabolites, including those involved in the arginine biosynthetic pathway. Pathway and network analysis of the metabolite profile show that ASS1 negative cells have altered arginine and citrulline metabolism as well as altered amino acid metabolism. As expected, we observed significant metabolite perturbations in ASS negative cells in response to ADI-PEG20 treatment. CONCLUSIONS: This study has highlighted significant differences in the metabolome of ASS1 negative and positive GBM which warrants further study to determine their diagnostic and therapeutic potential for the treatment of this devastating disease.

A Systems Oncology Approach Identifies NT5E as a Key Metabolic Regulator in Tumor Cells and Modulator of Platinum Sensitivity.

Altered metabolism in tumor cells is required for rapid proliferation but also can influence other phenotypes that affect clinical outcomes such as metastasis and sensitivity to chemotherapy. Here, a genome-wide association study (GWAS)-guided integration of NCI-60 transcriptome and metabolome data identified ecto-5'-nucleotidase (NT5E or CD73) as a major determinant of metabolic phenotypes in cancer cells. NT5E expression and associated metabolome variations were also correlated with sensitivity to several chemotherapeutics including platinum-based treatment. NT5E mRNA levels were observed to be elevated in cells upon in vitro and in vivo acquisition of platinum resistance in ovarian cancer cells, and specific targeting of NT5E increased tumor cell sensitivity to platinum. We observed that tumor NT5E levels were prognostic for outcomes in ovarian cancer and were elevated after treatment with platinum, supporting the translational relevance of our findings. In this work, we integrated and analyzed a plethora of public data, demonstating the merit of such a systems oncology approach for the discovery of novel players in cancer biology and therapy. We experimentally validated the main findings of the NT5E gene being involved in both intrinsic and acquired resistance to platinum-based drugs. We propose that the efficacy of conventional chemotherapy could be improved by NT5E inhibition and that NT5E expression may be a useful prognostic and predictive clinical biomarker.

Using value-based analysis to influence outcomes in complex surgical systems.

BACKGROUND: Value-based analysis (VBA) is a management strategy used to determine changes in value (quality/cost) when a usual practice (UP) is replaced by a best practice (BP). Previously validated in clinical initiatives, its usefulness in complex systems is unknown. To answer this question, we used VBA to correct deficiencies in cardiac surgery at Memorial Healthcare System. STUDY DESIGN: Cardiac surgery is a complex surgical system that lends itself to VBA because outcomes metrics provided by the Society of Thoracic Surgeons provide an estimate of quality; cost is available from Centers for Medicare and Medicaid Services and other contemporary sources; the UP can be determined; and the best practice can be established. RESULTS: Analysis of the UP at Memorial Healthcare System revealed considerable deficiencies in selection of patients for surgery; the surgery itself, including choice of procedure and outcomes; after care; follow-up; and control of expenditures. To correct these deficiencies, each UP was replaced with a BP. Changes included replacement of most of the cardiac surgeons; conversion to an employed physician model; restructuring of a heart surgery unit; recruitment of cardiac anesthesiologists; introduction of an interactive educational program; eliminating unsafe practices; and reducing cost. CONCLUSIONS: There was a significant (p < 0.01) reduction in readmissions, complications, and mortality between 2009 and 2013. Memorial Healthcare System was only 1 of 17 (1.7%) database participants (n = 1,009) to achieve a Society of Thoracic Surgeons 3-star rating in all 3 measured categories. Despite substantial improvements in quality, the cost per case and the length of stay declined. These changes created a savings opportunity of $14 million, with actual savings of $10.4 million. These findings suggest that VBA can be a powerful tool to enhance value (quality/cost) in a complex surgical system.

Right ventricular wall-motion changes after infant open heart surgery--a tissue Doppler study.

BACKGROUND: Right ventricular (RV) dysfunction is a well-recognized complication of cardiopulmonary bypass surgery (CPB) in adults. Infants and neonates may also be at high risk for this due to immature myocardium. Conventional assessment of RV function is just qualitative, but novel tissue Doppler echocardiographic (TDI) markers including peak systolic strain rate (SR) and isovolumic contraction acceleration (IVA) permit noninvasive quantitation of RV function. This study assessed myocardial velocities, IVA and SR in infants and neonates undergoing open heart surgery using TDI to study regional myocardial function perioperatively. METHODS: Transthoracic TDI data were obtained in the OR before and 24 hours post-CPB on 53 consecutive infants (age 0.39 ± 0.23 years). They were followed with TDI through hospital discharge. RESULTS: Mean CPB time was 87 ± 49 min (cross-clamp 52 ± 26 min). Peak systolic (STDI ) and diastolic myocardial velocities (ETDI , ATDI ), IVA, and peak SR were recorded in RV and LV from standard views for offline analysis. Postoperatively, LV systolic function and diastolic longitudinal function were unchanged or improved from baseline. LV radial velocities were increased postoperatively indicating adequate support. In contrast, RV longitudinal systolic and diastolic function was significantly diminished after CPB. RV changes persisted through hospital discharge. CONCLUSIONS: In infants and neonates, perioperative measurements of systolic and diastolic tissue Doppler parameters are feasible and revealed significant RV systolic and diastolic dysfunction post-CPB with preserved LV function. As such, TDI provides a sensitive tool to monitor the infant heart after CPB and may potentially be useful to assess different myocardial protection strategies.

Preliminary experience with cardiac reconstruction using decellularized porcine extracellular matrix scaffold: human applications in congenital heart disease.

An ideal material for repair of congenitally malformed hearts would encourage tissue regeneration with growth potential. Decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM) promotes tissue regeneration in animal models and noncardiac human applications. This retrospective review evaluates SIS-ECM for reconstruction of congenital heart defects. From June 2007 to May 2009, SIS-ECM patches were used in 43 operations on 40 patients aged 2 days to 13 years. In 16 cases, the SIS-ECM was used for pericardial closure. The SIS-ECM was used for cardiac or great vessel repair in 37 cases: atrial septal defect repair in 11, pulmonary arterioplasty in 10, right ventricular outflow tract patch in 6, pulmonary monocusp valve creation in 5, superior vena cava patch in 2 and aortoplasty in 2, valve leaflet augmentation in 2, and repair of unroofed coronary sinus in 1. Follow-up was complete. There were 5 deaths, all unrelated to the SIS-ECM. Mean follow-up was 7.85 months (0.5-24 months). No pericardial effusions or intracardiac or intravascular thromboses occurred related to the SIS-ECM. The patches did not shrink or calcify. Four of 5 monocusp valves were competent and none were stenotic. One patient who underwent tricuspid valve anterior leaflet augmentation with SIS-ECM required tricuspid valve replacement 4 months later for severe regurgitation following a catheter-based procedure. Explanted tissue showed resorption of the SIS-ECM, replacement with organized collagen, and re-endothelialization. Repair of congenital heart defects using SIS-ECM is feasible and safe. In valve reconstruction, this procedure shows potential for replacement by autologous tissue. Longer-term follow-up is required to assess the potential for growth.

Analysis of regional congenital cardiac surgical outcomes in Florida using the Society of Thoracic Surgeons Congenital Heart Surgery Database.

BACKGROUND: Florida is the fourth largest state in the United States of America. In 2004, 218,045 live babies were born in Florida, accounting for approximately 1744 new cases of congenital heart disease. We review the initial experience of The Society of Thoracic Surgeons Congenital Heart Surgery Database with a regional outcomes report, namely the Society of Thoracic Surgeons Florida Regional Report. METHODS: Eight centres in Florida provide services for congenital cardiac surgery. The Children's Medical Services of Florida provide a framework for quality improvement collaboration between centres. All congenital cardiac surgical centres in Florida have voluntarily agreed to submit data to the Society of Thoracic Surgeons Database. The Society of Thoracic Surgeons and Duke Clinical Research Institute prepared a Florida Regional Report to allow detailed regional analysis of outcomes for congenital cardiac surgery. RESULTS: The report of 2007 from the Society of Thoracic Surgeons Congenital Heart Surgery Database includes details of 61,014 operations performed during the 4 year data harvest window, which extended from 2003 through 2006. Of these operations, 6,385 (10.5%) were performed in Florida. Discharge mortality in the data from Florida overall, and from each Florida site, with 95% confidence intervals, is not different from cumulative data from the entire Society of Thoracic Surgeons Database, both for all patients and for patients stratified by complexity. CONCLUSIONS: A regional consortium of congenital heart surgery centres in Florida under the framework of the Children's Medical Services has allowed for inter-institutional collaboration with the goal of quality improvement. This experience demonstrates, first, that the database maintained by the Society of Thoracic Surgeons can provide the framework for regional analysis of outcomes, and second, that voluntary regional collaborative efforts permit the pooling of data for such analysis.