340 results found
Sarpaki S, Cortezon-Tamarit F, de Aguiar SRMM, et al., 2020, Radio- and nano-chemistry of aqueous Ga(iii) ions anchored onto graphene oxide-modified complexes., Nanoscale
The gallium-68 radiolabelling of new functional graphene oxide composites is reported herein along with kinetic stability investigations of the radio-nanohybrids under different environments and insights into their surface characteristics by SEM and XPS. The present work highlights the potential of graphene oxides as nanocarriers for small molecules such as bis(thiosemicarbazonato) complexes to act as multifunctional platforms for rapid and effective radioimaging agent incorporation.
Aboagye E, Dubash S, Keat N, et al., Clinical Translation of 18F-Fluoropivalate - A PET Tracer for Imaging Short-Chain Fatty Acid Metabolism: Safety, Biodistribution, and Dosimetry in Fed and Fasted Healthy Volunteers, European Journal of Nuclear Medicine and Molecular Imaging, ISSN: 1619-7070
Barnes EME, Xu Y, Benito A, et al., Lactic acidosis induces resistance to the pan-Akt inhibitor uprosertib in colon cancer cells, British Journal of Cancer, ISSN: 0007-0920
BackgroundAkt signalling regulates glycolysis and drives the Warburg effect in cancer, thus decreased glucose utilisation is a pharmacodynamic marker of Akt inhibition. However, cancer cells can utilise alternative nutrients to glucose for energy such as lactate, which is often elevated in tumours together with increased acidity. We therefore hypothesised that lactic acidosis may confer resistance to Akt inhibition.MethodsThe effect of the pan-Akt inhibitor uprosertib (GSK2141795), on HCT116 and LS174T colon cancer cells was evaluated in the presence and absence of lactic acid in vitro. Expression of downstream Akt signalling proteins was determined using a phosphokinase array and immunoblotting. Metabolism was assessed using 1H nuclear magnetic resonance spectroscopy, stable isotope labelling and gas chromatography-mass spectrometry.ResultsLactic acid-induced resistance to uprosertib was characterised by increased cell survival and reduced apoptosis. Uprosertib treatment reduced Akt signalling and glucose uptake irrespective of lactic acid supplementation. However, incorporation of lactate carbon and enhanced respiration was maintained in the presence of uprosertib and lactic acid. Inhibiting lactate transport or oxidative phosphorylation was sufficient to potentiate apoptosis in the presence of uprosertib.ConclusionsLactic acidosis confers resistance to uprosertib, which can be reversed by inhibiting lactate transport or oxidative metabolism.
Tarkin J, Wall C, Gopalan D, et al., A novel approach to imaging active Takayasu arteritis using somatostatin receptor PET/MRI ligands, Circulation: Cardiovascular Imaging, ISSN: 1941-9651
Glaser M, Rajkumar V, Diocou S, et al., 2019, One-pot radiosynthesis and biological evaluation of a caspase-3 selective 5-[(123,)(125) I]iodo-1,2,3-triazole derived satin SPECT tracer, Scientific Reports, Vol: 9, ISSN: 2045-2322
Induction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [18F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (123,125I) was achieved in 55 ± 12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [18F]ICMT11 (Ki = 6.1 ± 0.9 nM and 12.4 ± 4.7 nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.
Inglese M, Katherine L O, Lesley H, et al., 2019, Reliability of dynamic contrast enhanced magnetic resonance imaging data in primary brain tumours: a comparison of Tofts and shutter speed models, Neuroradiology, Vol: 61, Pages: 1375-1386, ISSN: 0028-3940
PurposeTo investigate the robustness of pharmacokinetic modelling of DCE-MRI brain tumourdata and to ascertain reliable perfusion parameters through a model selection processand a stability test.MethodsDCE-MRI data of 14 patients with primary brain tumours were analysed using the Toftsmodel (TM), the extended Tofts model (ETM), the shutter speed model (SSM) and theextended shutter speed model (ESSM). A no-effect model (NEM) was implemented toassess overfitting of data by the other models.For each lesion, the Akaike Information Criteria (AIC) was used to build a 3D modelselection map. The variability of each pharmacokinetic parameter extracted from thismap was assessed with a noise propagation procedure, resulting in voxel-wisedistributions of the coefficient of variation (CV).ResultsThe model selection map over all patients showed NEM had the best fit in 35.5% ofvoxels, followed by ETM (32%), TM (28.2%), SSM (4.3%) and ESSM (<0.1%). Inanalysing the reliability of Ktrans, when considering regions with a CV<20%, ≈25% ofvoxels were found to be stable across all patients. The remaining 75% of voxels wereconsidered unreliable.ConclusionsThe majority of studies quantifying DCE-MRI data in brain tumours only consider asingle model and whole-tumour statistics for the output parameters. Appropriate modelselection, considering tissue biology and its effects on blood brain barrier permeabilityand exchange conditions, together with an analysis on the reliability and stability of thecalculated parameters, is critical in processing robust brain tumour DCE-MRI data.
Sharma R, Wang WM, Yusuf S, et al., 2019, 68Ga-DOTATATE PET/CT parameters predict response to peptide receptor radionuclide therapy in neuroendocrine tumours, Radiotherapy and Oncology, Vol: 141, Pages: 108-115, ISSN: 0167-8140
PURPOSE: [177Lu]DOTATATE prolongs progression free survival (PFS) in metastatic neuroendocrine tumours (NETs). However, objective response rate is low. This, coupled with long duration of therapy and expense suggest need for better selection. We aim to assess whether baseline [68Ga]DOTATATE-PET/CT parameters, and whether response assessment by PET accurately predicts clinical outcome to [177Lu]DOTATATE. EXPERIMENTAL DESIGN: Retrospective study of patients receiving [177Lu]DOTATATE was conducted. Patients were followed 3-monthly until disease progression. Four [68Ga]DOTATATE-PET parameters (single lesion SUVmax, tumour to spleen and liver SUV ratios, and SUVmax-av using up to five target lesions in multiple organ sites) were determined at baseline and follow-up. The association between these PET parameters either at baseline, or any changes following treatment, and PET response criteria (PERCIST and modified PERCIST) to predict PFS were determined. Patients were followed 3-monthly until disease progression. Response was determined using RECIST 1.1. Baseline SSTR2 expression was assessed and compared with PET parameters. RESULTS: 55 patients with metastatic NETs were identified predominantly small bowel (N = 18) and pancreatic (N = 8) in origin. 16 were low grade, 15 intermediate and 3 high grade. Response to PRRT (N = 47): partial response (PR) 28%, stable disease (SD) 60% progressive disease (PD) 13%. Response to PRRT predicted PFS: PR 71.8 months (95%CI: not achieved), SD 29.1 months (95%CI: 15.2-43.1), and PD 9.7 months (95%CI: 0-21.02). Baseline, single lesion SUVmax predicted both response and PFS with SUV cut-off of 13.0 giving high sensitivity and specificity. Tumoural SUVmax correlated with SSTR2 expression, Spearman's rho - 0.69, p < 0.01. CONCLUSIONS: Baseline single lesion SUVmax and SUVmax-av predicts response to [177Lu]DOTATATE. Objective response following PRRT defines a subset of patients with markedly improved PFSBaseline SUVmax 13.0 defines a thre
Sharma R, Valls PO, Inglese M, et al., 2019, [18F]Fluciclatide PET as a biomarker of response to combination therapy of pazopanib and paclitaxel in platinum-resistant/refractory ovarian cancer, European Journal of Nuclear Medicine and Molecular Imaging, ISSN: 0340-6997
BACKGROUND: Angiogenesis is a driver of platinum resistance in ovarian cancer. We assessed the effect of combination pazopanib and paclitaxel followed by maintenance pazopanib in patients with platinum-resistant/refractory ovarian cancer. Integrins αvβ3 and αvβ5 are both upregulated in tumor-associated vasculature. [18F]Fluciclatide is a novel PET tracer that has high affinity for integrins αvβ3/5, and was used to assess the anti-angiogenic effect of pazopanib. PATIENTS AND METHODS: We conducted an open-label, phase Ib study in patients with platinum-resistant/refractory ovarian cancer. Patients received 1 week of single-agent pazopanib (800 mg daily) followed by combination therapy with weekly paclitaxel (80 mg/m2). Following completion of 18 weeks of combination therapy, patients continued with single-agent pazopanib until disease progression. Dynamic [18F]fluciclatide-PET imaging was conducted at baseline and after 1 week of pazopanib. Response (RECIST 1.1), toxicities, and survival outcomes were recorded. Circulating markers of angiogenesis were assessed with therapy. RESULTS: Fourteen patients were included in the intention-to-treat analysis. Complete and partial responses were seen in seven patients (54%). Median progression-free survival (PFS) was 10.63 months, and overall survival (OS) was 18.5 months. Baseline [18F]fluciclatide uptake was predictive of long PFS. Elevated baseline circulating angiopoietin and fibroblast growth factor (FGF) were predictive of greater reduction in SUV60,mean following pazopanib. Kinetic modeling of PET data indicated a reduction in K1 and Ki following pazopanib indicating reduced radioligand delivery and retention. CONCLUSIONS: Combination therapy followed by maintenance pazopanib is effective and tolerable in platinum-resistant/refractory ovarian cancer. [18F]Fluciclatide-PET uptake parameters predict clinical outcome with pazopanib therapy indicating an anti
Sharma R, Wang W, Yusuf S, et al., 2019, [Ga-68]-DOTATATE PET/CT parameters predict response to peptide receptor radionuclide therapy in neuroendocrine tumours, 32nd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), Publisher: SPRINGER, Pages: S640-S640, ISSN: 1619-7070
Allott L, Barnes C, Brickute D, et al., 2019, Solid-supported cyanoborohydride cartridges for automation of reductive amination radiochemistry, Reaction Chemistry and Engineering, Vol: 4, Pages: 1748-1751, ISSN: 2058-9883
A solid-supported cyanoborohydride cartridge was designed to facilitate the automated production of positron emission tomography (PET) radiotracers synthesised via reductive amination chemistry. Two compounds, N-(4-fluorobenzyl)-2-(2-nitro-1H-imidazol-1-yl)ethan-1-amine ([18F]2) and 1,3,4,6-tetra-O-acetyl-2-(4-fluorobenzylamine)-2-deoxy-β-D-glucopyranose ([18F]4) were radiosynthesised efficiently using a GE FASTlab™ platform, obtained in >98% RCP in a total synthesis time of 75 min (from the start of synthesis) with RCY (non-decay corrected) of 7.5 ± 2.5% and 6.0 ± 1.1%, respectively. The cartridge method provides a convenient alternative to conventional powdered reducing agents typically used in reductive amination radiochemistry.
Sharma R, Valls PO, Inglese M, et al., 2019, [F-18]fluciclatide Pet As A Biomarker Of Response To Combination Therapy Of Pazopanib And Paclitaxel In Platinum-resistant/refractory Ovarian Cancer, 32nd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), Publisher: SPRINGER, Pages: S223-S223, ISSN: 1619-7070
Trousil S, Lee P, Edwards RJ, et al., 2019, Altered cytochrome 2E1 and 3A P450-dependent drug metabolism in advanced ovarian cancer correlates to tumour-associated inflammation, British Journal of Pharmacology, Vol: 176, Pages: 3712-3722, ISSN: 0007-1188
Background and PurposePrevious work has focussed on changes in drug metabolism caused by altered activity of CYP3A in the presence of inflammation and, in particular, inflammation associated with malignancy. However, drug metabolism involves a number of other P450s, and therefore, we assessed the effect of cancer‐related inflammation on multiple CYP enzymes using a validated drug cocktail.Experimental ApproachPatients with advanced stage ovarian cancer and healthy volunteers were recruited. Participants received caffeine, chlorzoxazone, dextromethorphan, and omeprazole as in vivo probes for CYP1A2, CYP2E1, CYP2D6, CYP3A, and CYP2C19. Blood was collected for serum C‐reactive protein and cytokine analysis.Key ResultsCYP2E1 activity was markedly up‐regulated in cancer (6‐hydroxychlorzoxazone/chlorzoxazone ratio of 1.30 vs. 2.75), while CYP3A phenotypic activity was repressed in cancer (omeprazole sulfone/omeprazole ratio of 0.23 vs. 0.49). Increased activity of CYP2E1 was associated with raised serum levels of IL‐6, IL‐8, and TNF‐α. Repression of CYP3A correlated with raised levels of serum C‐reactive protein, IL‐6, IL‐8, and TNF‐α.Conclusions and ImplicationsCYP enzyme activity is differentially affected by the presence of tumour‐associated inflammation, affecting particularly CYP2E1‐ and CYP3A‐mediated drug metabolism, and may have profound implications for drug development and prescribing in oncological settings.
Brickute D, Kaliszczak M, Barnes C, et al., 2019, Development and evaluation of an 18F-radiolabeled monocyclam derivative for imaging CXCR4 expression, Molecular Pharmaceutics, Vol: 16, Pages: 2106-2117, ISSN: 1543-8384
In humans, C–X–C chemokine receptor type 4 (CXCR4) is a protein that is encoded by the CXCR4 gene and binds the ligand CXCL12 (also known as SDF-1). The CXCR4–CXCL12 interaction in cancer elicits biological activities that result in tumor progression and has accordingly been the subject of significant investigation for detection and treatment of the disease. Peptidic antagonists have been labeled with a variety of radioisotopes for the detection of CXCR4, but the methodology utilizing small molecules has predominantly used radiometals. We report here the development of a 18F-radiolabeled cyclam-based small molecule radioprobe, [18F]MCFB, for imaging CXCR4 expression. The IC50 value of [19F]MCFB for CXCR4 was similar to that of AMD3465 (111.3 and 89.8 nM, respectively). In vitro binding assays show that the tracer depicted a differential CXCR4 expression, which was blocked in the presence of AMD3465, demonstrating the specificity of [18F]MCFB. Positron emission tomography (PET) imaging studies showed a distinct uptake of the radioprobe in lymphoma and breast cancer xenografts. High liver and kidney uptakes were seen with [18F]MCFB, leading us to further examine the basis of its pharmacokinetics in relation to the tracer’s cationic nature and thus the role of organic cation transporters (OCTs). Substrate competition following the intravenous injection of metformin led to a marked decrease in the urinary excretion of [18F]MCFB, with moderate changes observed in other organs, including the liver. Our results suggest involvement of OCTs in the renal elimination of the tracer. In conclusion, the 18F-radiolabeled monocyclam, [18F]MCFB, has potential to detect tumor CXCR4 in nonhepatic tissues.
Leow CH, Bush N, Stanziola A, et al., 2019, 3D microvascular imaging using high frame rate ultrasound and ASAP without contrast agents: development and initial in vivo evaluation on non-tumour and tumour models, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 66, Pages: 939-948, ISSN: 0885-3010
Three-dimensional imaging is valuable to non-invasively assess angiogenesis given the complex 3D architecture of vascular networks. The emergence of high frame rate (HFR) ultrasound, which can produce thousands of images per second, has inspired novel signal processing techniques and their applications in structural and functionalimaging of blood vessels. Although highly sensitive vascular mapping has been demonstrated using ultrafast Doppler, the detectability of microvasculature from the background noise may be hindered by the low signal to noise ratio (SNR) particularly in deeper region and without the use of contrast agents. We have recently demonstrated a coherence based technique, acoustic sub-aperture imaging (ASAP), for super-contrast vascular imaging and illustrated the contrast improvement using HFR contrast-enhanced ultrasound. In this work, we provide a feasibility study for microvascular imaging using ASAP without contrast agents, and extend its capability from 2D to volumetric vascular mapping. Using an ultrasound research system and a pre-clinical probe, we demonstrated the improved visibility of microvascular mapping using ASAP in comparison to ultrafast Power Doppler (PD) on a mouse kidney, liver and tumour without contrast agent injection. The SNR of ASAP images improves in average by 10dB when compared to PD. Besides, directional velocity mappings were also demonstrated by combining ASAP with the phase information extracted from lag-1 autocorrelation. Three-dimensional vascular and velocity mapping of the mouse kidney, liver and tumour were demonstrated by stackingthe ASAP images acquired using 2D ultrasound imaging and a trigger-controlled linear translation stage. The 3D results depicted clear micro-vasculature morphologies and function
Lavdas I, Glocker B, Rueckert D, et al., 2019, Machine learning in whole-body MRI: experiences and challenges from an applied study using multicentre data, CLINICAL RADIOLOGY, Vol: 74, Pages: 346-356, ISSN: 0009-9260
Hernandez-Gil J, Braga M, Harriss B, et al., 2019, Development of Ga-68-labelled ultrasound microbubbles for whole-body PET imaging, Chemical Science, Vol: 10, Pages: 5603-5615, ISSN: 2041-6520
Microbubble (MB) contrast agents have revolutionalised the way ultrasound (US) imaging can be used clinically and pre-clinically. Contrast-enhanced US offers improvements in soft-tissue contrast, as well as the ability to visualise disease processes at the molecular level. However, its inability to provide in vivo whole-body imaging can hamper the development of new MB formulations. Herein, we describe a fast and efficient method for achieving 68Ga-labelling of MBs after a direct comparison of two different strategies. The optimised approach produces 68Ga-labelled MBs in good yields through the bioorthogonal inverse-electron-demand Diel–Alder reaction between a trans-cyclooctene-modified phospholipid and a new tetrazine-bearing HBED-CC chelator. The ability to noninvasively study the whole-body distribution of 68Ga-labelled MBs was demonstrated in vivo using positron emission tomography (PET). This method could be broadly applicable to other phospholipid-based formulations, providing accessible solutions for in vivo tracking of MBs.
Ferris T, Carroll L, Mease RC, et al., 2019, Iodination of terminal alkynes using KI/CuSO4 – A facile method with potential for radio-iodination, Tetrahedron Letters, Vol: 60, Pages: 936-939, ISSN: 0040-4039
Herein, we report an efficient new method for the iodination of terminal alkynes using stoichiometric KI and CuSO4 in a mix of acetonitrile and acetate buffer that holds promise for further development into a method for radio-iodination.
Pinato D, Brown MW, Trousil S, et al., 2019, Integrated analysis of multiple receptor tyrosine kinases identifies Axl as a therapeutic target and mediator of resistance to sorafenib in hepatocellular carcinoma., British Journal of Cancer, Vol: 120, Pages: 512-521, ISSN: 0007-0920
Background: Aberrant activation of Axl is implicated in the progression of HCC. We explored biologic significance and preclinical efficacy of Axl inhibition as a therapeutic strategy in sorafenib-naïve and resistant HCC.Methods: We evaluated Axl expression in sorafenib-naïve and resistant (SR) clones of epithelial (HuH7) and mesenchymal origin (SKHep-1) using antibody arrays and confirmed tissue expression. We tested the effect of Axl inhibition with RNA-interference and pharmacologically with R428 on a number of phenotypic assays. Results: Axl mRNA overexpression in cell lines (n=28) and RNA-seq tissue datasets (n=373) correlated with epithelial-to-mesenchymal transition (EMT). Axl was overexpressed in HCC compared to cirrhosis and normal liver. We confirmed sorafenib-resistance to be associated with EMT and enhanced motility in both HuH7-SR and SKHep-1-SR cells documenting a 4-fold increase in Axl phosphorylation as an adaptive feature of chronic sorafenib treatment in SKHep-1-SR cells. Axl inhibition reduced motility and enhanced sensitivity to sorafenib in SKHep-1SR cells. In patients treated with sorafenib (n=40) circulating Axl levels correlated with shorter survival.Conclusions: Suppression of Axl-dependent signaling influences the transformed phenotype in HCC cells and contributes to adaptive resistance to sorafenib, providing a pre-clinical rationale for the development of Axl inhibitors as a measure to overcome sorafenib resistance.
Allott L, Barnes C, Brickute D, et al., 2019, An improved automated radiosynthesis of [F-18]FET-beta AG-TOCA, Reaction Chemistry and Engineering, Vol: 4, Pages: 569-574, ISSN: 2058-9883
The fluorine-18 radiolabelled octreotide derivative [18F]FET-βAG-TOCA targeting somatostatin receptor type 2, has been evaluated clinically for positron emission tomography (PET) imaging of neuroendocrine tumours (NETs). We report an improved automated radiosynthesis of [18F]FET-βAG-TOCA with several advantages over the current automated GMP synthesis: 1) cartridge-based purification of 2-[18F]fluoroethylazide ([18F]FEA); 2) simple set-up for the radiolabelling on a single cassette; 3) HPLC purification using a biocompatible mobile phase. [18F]FET-βAG-TOCA was produced with a radiochemical yield of 16.7 ± 0.6% (non-decay corrected) and radiochemical purity ≥98%. The automated synthesis produced multi-patient doses (900 MBq) that were radiochemically stable (≥98%) over 4 hours. In addition, the automated procedure described can be used, with minimal adaptation, to radiolabel any alkyne-containing peptide with [18F]FEA using the GE FASTlab™ platform.
Przystal J, Waramit S, Pranjol MZI, et al., 2019, Efficacy of systemic temozolomide-activated phage-targeted gene therapy in human glioblastoma, EMBO Molecular Medicine, Vol: 11, ISSN: 1757-4676
Glioblastoma multiforme (GBM) is the most lethal primary intracranial malignant neoplasm in adults and most resistant to treatment. Integration of gene therapy and chemotherapy, chemovirotherapy, has the potential to improve treatment. We have introduced an intravenous bacteriophage (phage) vector for dual targeting of therapeutic genes to glioblastoma. It is a hybrid AAV/phage, AAVP, designed to deliver a recombinant adeno‐associated virus genome (rAAV) by the capsid of M13 phage. In this vector, dual tumor targeting is first achieved by phage capsid display of the RGD4C ligand that binds the αvβ3 integrin receptor. Second, genes are expressed from a tumor‐activated and temozolomide (TMZ)‐induced promoter of the glucose‐regulated protein, Grp78. Here, we investigated systemic combination therapy using TMZ and targeted suicide gene therapy by the RGD4C/AAVP‐Grp78. Firstly, in vitro we showed that TMZ increases endogenous Grp78 gene expression and boosts transgene expression from the RGD4C/AAVP‐Grp78 in human GBM cells. Next, RGD4C/AAVP‐Grp78 targets intracranial tumors in mice following intravenous administration. Finally, combination of TMZ and RGD4C/AAVP‐Grp78 targeted gene therapy exerts a synergistic effect to suppress growth of orthotopic glioblastoma.
Hau Leow C, Bush NL, Stanziola A, et al., 2019, High-contrast 3D in vivo microvascular imaging using scanning 2D ultrasound and acoutic sub-aperture processing (ASAP), IEEE International Ultrasonics Symposium, IUS. 2018, Publisher: IEEE, ISSN: 1948-5719
Non-invasive techniques for microvascular environment assessment are invaluable for clinical diagnosis and treatment monitoring. We recently developed a super contrast processing to suppress noise background in ultrafast Power Doppler, known an acoustic sub-aperture processing (ASAP), and demonstrate using 2D contrast enhance ultrasound. However, 2D imaging is insufficient to represent the 3D complex vascular environment. We therefore extend our study to demonstrate the feasibility of our technique for volumetric imaging. A pseudo-3D imaging technique was developed and demonstrated using a research system and preclinical transducer. A mouse liver was scanned using 2D ultrafast ultrasound and a mechanical translation stage. Initial results not only demonstrated a substantial noise reduction in 2D vascular images using ASAP, but also a high contrast volumetric rendering of a mouse liver. Our technique is ready for clinical use to provide better evaluation of angiogenesis.
Leow CH, Braga M, Bush NL, et al., 2019, Contrast vs non-contrast enhanced microvascular imaging using acoustic sub-aperture processing (ASAP): in vivo demonstration, IEEE International Ultrasonics Symposium, IUS. 2018, Publisher: IEEE, ISSN: 1948-5719
Angiogenesis plays a vital role in the progression of cancer. Non-invasive imaging techniques capable of assessing the microenvironment are therefore of clinical interest. Although highly sensitive vascular mapping has been demonstrated using ultrafast Power Doppler (PD), the detectability of microvasculature from the background noise may be hindered by the low signal-to-noise ratio (SNR) in deeper region and without the use of contrast agents. We recently developed acoustic sub-aperture processing (ASAP) processing for super-contrast vasculature imaging. This technique relies on the spatial coherence of the backscattered echoes over different acquisitions to substantially reduce the noise floor compared to the power Doppler (PD) technique. In this study, we demonstrate the feasibility of applying ASAP processing for non-contrast enhanced microvascular imaging in preclinical condition, and compare it with contrast enhanced ASAP as well as ultrafast PD. Comparing to PD, ASAP exhibit SNR improvement up to 12 dB. Higher SNR and extra visibility of smaller vessel are also demonstrated in contrast enhanced images in comparison to the non-contrast images. In conclusion, we have demonstrated the feasibility of using ASAP in vivo for non-contrast microvascular imaging, and the added benefit of using contrast agents in microvascular imaging.
Vassileva V, Stribbling S, Barnes C, et al., 2019, Evaluation of apoptosis imaging biomarkers in a genetic model of cell death, EJNMMI Research, Vol: 9, ISSN: 2191-219X
PurposeWe have previously developed the caspase-based radiotracer, 18F-ICMT-11, for PET imaging to monitor treatment response. We further validated 18F-ICMT-11 specificity in a murine melanoma death-switch tumour model with conditional activation of caspase-3 induced by doxycycline.MethodsCaspase-3/7 activity and cellular uptake of 18F-ICMT-11, 18F-ML-10 and 18F-FDG were assessed in B16ova and B16ovaRevC3 cells after death-switch induction.Death-switch induction was confirmed in vivo in xenograft tumours, and 18F-ICMT-11 and 18F-ML-10 biodistribution was assessed by ex vivo gamma counting of select tissues. PET imaging was performed with 18F-ICMT-11, 18F-ML-10 and 18F-FDG. Caspase-3 activation was confirmed by immunohistochemistry.ResultsSignificantly increased caspase-3/7 activity was observed only in B16ovaRevC3 cells after death-switch induction, accompanied by significantly increased 18F-ICMT-11 (p < 0.001) and 18F-ML-10 (p < 0.05) and decreased 18F-FDG (p < 0.001) uptake compared with controls.B16ova and B16ovaRevC3 tumours had similar growth in vivo; however, B16ovaRevC3 growth was significantly reduced with death-switch induction (p < 0.01). Biodistribution studies showed significantly increased 18F-ICMT-11 tumour uptake following death-switch induction (p < 0.01), but not for 18F-ML-10. Tumour uptake of 18F-ICMT-11 was higher than that of 18F-ML-10 after death-switch induction. PET imaging studies showed that 18F-ICMT-11 can be used to detect apoptosis after death-switch induction, which was accompanied by significantly increased expression of cleaved caspase-3. 18F-FDG signal decreased in tumours after death-switch induction.ConclusionsWe demonstrate that 18F-ICMT-11 can be used to detect caspase-3 activation in a death-switch tumour model, independent of the confounding effects of cancer therapeutics, thus confirming its specificity and supporting the development of this r
Lu H, Arshad M, Thornton A, et al., 2019, A mathematical-descriptor of tumor-mesoscopic-structure from computed-tomography images annotates prognostic and molecular-phenotypes of epithelial ovarian cancer, Nature Communications, Vol: 10, ISSN: 2041-1723
The five-year survival rate of epithelial ovarian cancer (EOC) is approximately 35–40% despite maximal treatment efforts, highlighting a need for stratification biomarkers for personalized treatment. Here we extract 657 quantitative mathematical descriptors from the preoperative CT images of 364 EOC patients at their initial presentation. Using machine learning, we derive a non-invasive summary-statistic of the primary ovarian tumor based on 4 descriptors, which we name “Radiomic Prognostic Vector” (RPV). RPV reliably identifies the 5% of patients with median overall survival less than 2 years, significantly improves established prognostic methods, and is validated in two independent, multi-center cohorts. Furthermore, genetic, transcriptomic and proteomic analysis from two independent datasets elucidate that stromal phenotype and DNA damage response pathways are activated in RPV-stratified tumors. RPV and its associated analysis platform could be exploited to guide personalized therapy of EOC and is potentially transferrable to other cancer types.
Jones DT, Valli A, Haider S, et al., 2019, 3D Growth of Cancer Cells Elicits Sensitivity to Kinase Inhibitors but Not Lipid Metabolism Modifiers, MOLECULAR CANCER THERAPEUTICS, Vol: 18, Pages: 376-388, ISSN: 1535-7163
Arshad MA, Thornton A, Lu H, et al., 2019, Discovery of pre-therapy 2-deoxy-2-F-18-fluoro-D-glucose positron emission tomography-based radiomics classifiers of survival outcome in non-small-cell lung cancer patients, European Journal of Nuclear Medicine and Molecular Imaging, Vol: 46, Pages: 455-466, ISSN: 0340-6997
PurposeThe aim of this multi-center study was to discover and validate radiomics classifiers as image-derived biomarkers for risk stratification of non-small-cell lung cancer (NSCLC).Patients and methodsPre-therapy PET scans from a total of 358 Stage I–III NSCLC patients scheduled for radiotherapy/chemo-radiotherapy acquired between October 2008 and December 2013 were included in this seven-institution study. A semi-automatic threshold method was used to segment the primary tumors. Radiomics predictive classifiers were derived from a training set of 133 scans using TexLAB v2. Least absolute shrinkage and selection operator (LASSO) regression analysis was used for data dimension reduction and radiomics feature vector (FV) discovery. Multivariable analysis was performed to establish the relationship between FV, stage and overall survival (OS). Performance of the optimal FV was tested in an independent validation set of 204 patients, and a further independent set of 21 (TESTI) patients.ResultsOf 358 patients, 249 died within the follow-up period [median 22 (range 0–85) months]. From each primary tumor, 665 three-dimensional radiomics features from each of seven gray levels were extracted. The most predictive feature vector discovered (FVX) was independent of known prognostic factors, such as stage and tumor volume, and of interest to multi-center studies, invariant to the type of PET/CT manufacturer. Using the median cut-off, FVX predicted a 14-month survival difference in the validation cohort (N = 204, p = 0.00465; HR = 1.61, 95% CI 1.16–2.24). In the TESTI cohort, a smaller cohort that presented with unusually poor survival of stage I cancers, FVX correctly indicated a lack of survival difference (N = 21, p = 0.501). In contrast to the radiomics classifier, clinically routine PET variables including SUVmax, SUVmean and SUVpeak lacked any prognostic information.ConclusionPET-based radiomics classifiers deriv
Theodorou I, Ruenraroengsak P, Carter D, et al., 2019, Towards multiplexed near-infrared cellular imaging using gold nanostar arrays with tunable fluorescence enhancement, Nanoscale, Vol: 11, Pages: 2079-2088, ISSN: 2040-3364
Sensitive detection of disease biomarkers expressed by human cells is critical to the development of novel diagnostic and therapeutic methods. Here we report that plasmonic arrays based on gold nanostar (AuNS) monolayers enable up to 19-fold fluorescence enhancement for cellular imaging in the near-infrared (NIR) biological window, allowing the application of low quantum yield fluorophores for sensitive cellular imaging. The high fluorescence enhancement together with low autofluorescence interference in this wavelength range enable higher signal-to-noise ratio compared to other diagnostic modalities. Using AuNSs of different geometries and therefore controllable electric field enhancement, cellular imaging with tunable enhancement factors is achieved, which may be useful for the development of multicolour and multiplexed platforms for a panel of biomarkers, allowing to distinguish different subcell populations at the single cell level. Finally, the uptake of AuNSs within HeLa cells and their high biocompatibility, pave the way for novel high-performance in vitro and in vivo diagnostic platforms.
Fu R, Carroll L, Yahioglu GK, et al., 2018, Antibody fragment and affibody immunoPET imaging agents: radiolabelling strategies and applications, ChemMedChem, Vol: 13, Pages: 2466-2478, ISSN: 1860-7187
Antibodies have long been recognised as potent vectors for carrying diagnostic medical radionuclides, contrast agents and optical probes to diseased tissue for imaging. The area of ImmunoPET combines the use of positron emission tomography (PET) imaging with antibodies to improve the diagnosis, staging and monitoring of diseases. Recent developments in antibody engineering and PET radiochemistry have led to a new wave of experimental ImmunoPET imaging agents that are based on a range of antibody fragments and affibodies. In contrast to full antibodies, engineered affibody proteins and antibody fragments such as minibodies, diabodies, single‐chain variable region fragments (scFvs), and nanobodies are much smaller but retain the essential specificities and affinities of full antibodies in addition to more desirable pharmacokinetics for imaging. Herein, recent key developments in the PET radiolabelling strategies of antibody fragments and related affibody molecules are highlighted, along with the main PET imaging applications of overexpressed antigen‐associated tumours and immune cells.
Dubash SR, Merchant S, Heinzmann K, et al., 2018, Clinical translation of [F-18]ICMT-11 for measuring chemotherapy-induced caspase 3/7 activation in breast and lung cancer, European Journal of Nuclear Medicine and Molecular Imaging, Vol: 45, Pages: 2285-2299, ISSN: 1619-7070
BackgroundEffective anticancer therapy is thought to involve induction of tumour cell death through apoptosis and/or necrosis. [18F]ICMT-11, an isatin sulfonamide caspase-3/7-specific radiotracer, has been developed for PET imaging and shown to have favourable dosimetry, safety, and biodistribution. We report the translation of [18F]ICMT-11 PET to measure chemotherapy-induced caspase-3/7 activation in breast and lung cancer patients receiving first-line therapy.ResultsBreast tumour SUVmax of [18F]ICMT-11 was low at baseline and unchanged following therapy. Measurement of M30/M60 cytokeratin-18 cleavage products showed that therapy was predominantly not apoptosis in nature. While increases in caspase-3 staining on breast histology were seen, post-treatment caspase-3 positivity values were only approximately 1%; this low level of caspase-3 could have limited sensitive detection by [18F]ICMT-11-PET. Fourteen out of 15 breast cancer patients responded to first–line chemotherapy (complete or partial response); one patient had stable disease. Four patients showed increases in regions of high tumour [18F]ICMT-11 intensity on voxel-wise analysis of tumour data (classed as PADS); response was not exclusive to patients with this phenotype. In patients with lung cancer, multi-parametric [18F]ICMT-11 PET and MRI (diffusion-weighted- and dynamic contrast enhanced-MRI) showed that PET changes were concordant with cell death in the absence of significant perfusion changes.ConclusionThis study highlights the potential use of [18F]ICMT-11 PET as a promising candidate for non-invasive imaging of caspase3/7 activation, and the difficulties encountered in assessing early-treatment responses. We summarize that tumour response could occur in the absence of predominant chemotherapy-induced caspase-3/7 activation measured non-invasively across entire tumour lesions in patients with breast and lung cancer.
Kaliszczak M, Hechanova E, Alsadah H, et al., 2018, The HDAC6 inhibitor C1A modulates autophagy substrates in diverse cancer cells and induces cell death, British Journal of Cancer, Vol: 119, Pages: 1278-1287, ISSN: 0007-0920
BACKGROUND: Cytosolic Deacetylase HDAC6 is involved in the autophagy degradationpathway of malformed proteins, an important survival mechanism in cancer cells. Weevaluated modulation of autophagy-related proteins and cell death by the HDAC6-selectiveinhibitor C1A.METHODS: Autophagy substrates (LC3 and p62 proteins) and endoplasmic reticulum (ER)stress phenotype were determined. Caspase 3/7 activation and cellular proliferation assayswere used to assess consequences of autophagy modulation.RESULTS: C1A potently resolved autophagy substrates induced by 3-MA and chloroquine.The mechanism of autophagy inhibition by HDAC6 genetic knockout or C1A treatmentwas consistent with abrogation of autophagosome-lysosome fusion, and decrease of Mycprotein. C1A alone or combined with the proteasome inhibitor, bortezomib, enhanced celldeath in malignant cells demonstrating the complementary roles of the proteasome andautophagy pathways for clearing malformed proteins. Myc positive neuroblastoma, KRASpositive colorectal cancer and multiple myeloma cells showed marked cell growthinhibition in response to HDAC6 inhibitors. Finally, growth of neuroblastoma xenograftswas arrested in vivo by single agent C1A, while combination with bortezomib slowed thegrowth of colorectal cancer xenografts.CONCLUSIONS: C1A resolves autophagy substrates in malignant cells and induces celldeath, warranting its use for in vivo pre-clinical autophagy research.
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