β-1,3-d-Glucan is a ubiquitous glucose polymer produced by plants, bacteria, and most fungi. It has been used as a diagnostic tool in patients with invasive mycoses via a highly-sensitive reagent consisting of the blood coagulation system of horseshoe crab. However, no method is currently available for measuring β-1,6-glucan, another primary β-glucan structure of fungal polysaccharides. Herein, we describe the development of an economical and highly-sensitive and specific assay for β-1,6-glucan using a modified recombinant endo-β-1,6-glucanase having diminished glucan hydrolase activity. The purified β-1,6-glucanase derivative bound to the β-1,6-glucan pustulan with a KD of 16.4 nm. We validated the specificity of this β-1,6-glucan probe by demonstrating its ability to detect cell wall β-1,6-glucan from both yeast and hyphal forms of the opportunistic fungal pathogen Candida albicans, without any detectable binding to glucan lacking the long β-1,6-glucan branch. We developed a sandwich ELISA-like assay with a low limit of quantification for pustulan (1.5 pg/ml), and we successfully employed this assay in the quantification of extracellular β-1,6-glucan released by >250 patient-derived strains of different Candida species (including Candida auris) in culture supernatant in vitro. We also used this assay to measure β-1,6-glucan in vivo in the serum and in several organs in a mouse model of systemic candidiasis. Our work describes a reliable method for β-1,6-glucan detection, which may prove useful for the diagnosis of invasive fungal infections.

Purinergic signaling by extracellular ATP regulates a variety of cellular events and is implicated in both normal physiology and pathophysiology. Several molecules have been associated with the release of ATP and other small molecules, but their precise contributions have been difficult to assess because of their complexity and heterogeneity. Here, we report on the results of a gain-of-function screen for modulators of hypotonicity-induced ATP release using HEK-293 cells and murine cerebellar granule neurons, along with bioluminescence, calcium FLIPR, and short hairpin RNA–based gene-silencing assays. This screen utilized the most extensive genome-wide ORF collection to date, covering 90% of human, nonredundant, protein-encoding genes. We identified two ABCG1 (ABC subfamily G member 1) variants, which regulate cellular cholesterol, as modulators of hypotonicity-induced ATP release. We found that cholesterol levels control volume-regulated anion channel–dependent ATP release. These findings reveal novel mechanisms for the regulation of ATP release and volume-regulated anion channel activity and provide critical links among cellular status, cholesterol, and purinergic signaling.

Bacterial biofilms are cellular communities that produce an adherent matrix. Exopolysaccharides are key structural components of this matrix and are required for the assembly and architecture of biofilms produced by a wide variety of microorganisms. The human bacterial pathogens Escherichia coli and Salmonella enterica produce a biofilm matrix composed primarily of the exopolysaccharide phosphoethanolamine (pEtN) cellulose. Once thought to be composed of only underivatized cellulose, the pEtN modification present in these matrices has been implicated in the overall architecture and integrity of the biofilm. However, an understanding of the mechanism underlying pEtN derivatization of the cellulose exopolysaccharide remains elusive. The bacterial cellulose synthase subunit G (BcsG) is a predicted inner membrane–localized metalloenzyme that has been proposed to catalyze the transfer of the pEtN group from membrane phospholipids to cellulose. Here we present evidence that the C-terminal domain of BcsG from E. coli (EcBcsGΔN) functions as a phosphoethanolamine transferase in vitro with substrate preference for cellulosic materials. Structural characterization of EcBcsGΔN revealed that it belongs to the alkaline phosphatase superfamily, contains a Zn2+ ion at its active center, and is structurally similar to characterized enzymes that confer colistin resistance in Gram-negative bacteria. Informed by our structural studies, we present a functional complementation experiment in E. coli AR3110, indicating that the activity of the BcsG C-terminal domain is essential for integrity of the pellicular biofilm. Furthermore, our results established a similar but distinct active-site architecture and catalytic mechanism shared between BcsG and the colistin resistance enzymes.

Extracellular matrix-evoked angiostasis and autophagy within the tumor microenvironment represent two critical, but unconnected, functions of the small leucine-rich proteoglycan, decorin. Acting as a partial agonist of vascular endothelial growth factor 2 (VEGFR2), soluble decorin signals via the energy sensing protein, AMP-activated protein kinase (AMPK), in the autophagic degradation of intracellular vascular endothelial growth factor A (VEGFA). Here, we discovered that soluble decorin evokes intracellular catabolism of endothelial VEGFA that is mechanistically independent of mTOR, but requires an autophagic regulator, paternally expressed gene 3 (PEG3). We found that administration of autophagic inhibitors such as chloroquine or bafilomycin A1, or depletion of autophagy-related 5 (ATG5), results in accumulation of intracellular VEGFA, indicating that VEGFA is a basal autophagic substrate. Mechanistically, decorin increased the VEGFA clearance rate by augmenting autophagic flux, a process that required RAB24 member RAS oncogene family (RAB24), a small GTPase that facilitates the disposal of autophagic compartments. We validated these findings by demonstrating the physiological relevance of this process in vivo. Mice starved for 48 h exhibited a sharp decrease in overall cardiac and aortic VEGFA that could be blocked by systemic chloroquine treatment. Thus, our findings reveal a unified mechanism for the metabolic control of endothelial VEGFA for autophagic clearance in response to decorin and canonical pro-autophagic stimuli. We posit that the VEGFR2/AMPK/PEG3 axis integrates the anti-angiogenic and pro-autophagic bioactivities of decorin as the molecular basis for tumorigenic suppression. These results support future therapeutic use of decorin as a next-generation protein therapy to combat cancer.

Heat shock factor 1 (HSF1) regulates cellular adaptation to challenges such as heat shock and oxidative and proteotoxic stresses. We have recently reported a previously unappreciated role for HSF1 in the regulation of energy metabolism in fat tissues; however, whether HSF1 is differentially expressed in adipose depots and how its levels are regulated in fat tissues remain unclear. Here, we show that HSF1 levels are higher in brown and subcutaneous fat tissues than in those in the visceral depot and that HSF1 is more abundant in differentiated, thermogenic adipocytes. Gene expression experiments indicated that HSF1 is transcriptionally regulated in fat by agents that modulate cAMP levels, by cold exposure, and by pharmacological stimulation of β-adrenergic signaling. An in silico promoter analysis helped identify a putative response element for activating transcription factor 3 (ATF3) at −258 to −250 base pairs from the HSF1 transcriptional start site, and electrophoretic mobility shift and ChIP assays confirmed ATF3 binding to this sequence. Furthermore, functional assays disclosed that ATF3 is necessary and sufficient for HSF1 regulation. Detailed gene expression analysis revealed that ATF3 is one of the most highly induced ATFs in thermogenic tissues of mice exposed to cold temperatures or treated with the β-adrenergic receptor agonist CL316,243 and that its expression is induced by modulators of cAMP levels in isolated adipocytes. To the best of our knowledge, our results show for the first time that HSF1 is transcriptionally controlled by ATF3 in response to classic stimuli that promote heat generation in thermogenic tissues.

We previously reported that overexpression of cytochrome P450 family 24 subfamily A member 1 (CYP24A1) increases lung cancer cell proliferation by activating RAS signaling and that CYP24A1 knockdown inhibits tumor growth. However, the mechanism of CYP24A1-mediated cancer cell proliferation remains unclear. Here, we conducted cell synchronization and biochemical experiments in lung adenocarcinoma cells, revealing a link between CYP24A1 and anaphase-promoting complex (APC), a key cell cycle regulator. We demonstrate that CYP24A1 expression is cell cycle–dependent; it was higher in the G2-M phase and diminished upon G1 entry. CYP24A1 has a functional destruction box (D-box) motif that allows binding with two APC adaptors, CDC20-homologue 1 (CDH1) and cell division cycle 20 (CDC20). Unlike other APC substrates, however, CYP24A1 acted as a pseudo-substrate, inhibiting CDH1 activity and promoting mitotic progression. Conversely, overexpression of a CYP24A1 D-box mutant compromised CDH1 binding, allowing CDH1 hyperactivation, thereby hastening degradation of its substrates cyclin B1 and CDC20, and accumulation of the CDC20 substrate p21, prolonging mitotic exit. These activities also occurred with a CYP24A1 isoform 2 lacking the catalytic cysteine (Cys-462), suggesting that CYP24A1's oncogenic potential is independent of its catalytic activity. CYP24A1 degradation reduced clonogenic survival of mutant KRAS-driven lung cancer cells, and calcitriol treatment increased CYP24A1 levels and tumor burden in Lsl-KRASG12D mice. These results disclose a catalytic activity-independent growth-promoting role of CYP24A1 in mutant KRAS-driven lung cancer. This suggests that CYP24A1 could be therapeutically targeted in lung cancers in which its expression is high.

Fatty acid esters of hydroxy fatty acids (FAHFAs) are a newly discovered class of signaling lipids with anti-inflammatory and anti-diabetic properties. However, the endogenous regulation of FAHFAs remains a pressing but unanswered question. Here, using MS-based FAHFA hydrolysis assays, LC-MS–based lipidomics analyses, and activity-based protein profiling, we found that androgen-induced gene 1 (AIG1) and androgen-dependent TFPI-regulating protein (ADTRP), two threonine hydrolases, control FAHFA levels in vivo in both genetic and pharmacologic mouse models. Tissues from mice lacking ADTRP (Adtrp-KO), or both AIG1 and ADTRP (DKO) had higher concentrations of FAHFAs particularly isomers with the ester bond at the 9th carbon due to decreased FAHFA hydrolysis activity. The levels of other lipid classes were unaltered indicating that AIG1 and ADTRP specifically hydrolyze FAHFAs. Complementing these genetic studies, we also identified a dual AIG1/ADTRP inhibitor, ABD-110207, which is active in vivo. Acute treatment of WT mice with ABD-110207 resulted in elevated FAHFA levels, further supporting the notion that AIG1 and ADTRP activity control endogenous FAHFA levels. However, loss of AIG1/ADTRP did not mimic the changes associated with pharmacologically administered FAHFAs on extent of upregulation of FAHFA levels, glucose tolerance, or insulin sensitivity in mice, indicating that therapeutic strategies should weigh more on FAHFA administration. Together, these findings identify AIG1 and ADTRP as the first endogenous FAHFA hydrolases identified and provide critical genetic and chemical tools for further characterization of these enzymes and endogenous FAHFAs to unravel their physiological functions and roles in health and disease.

The ribosome biogenesis factor Las1 is an essential endoribonuclease that is well-conserved across eukaryotes and a newly established member of the higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain-containing nuclease family. HEPN nucleases participate in diverse RNA cleavage pathways and share a short HEPN nuclease motif (RφXXXH) important for RNA cleavage. Most HEPN nucleases participate in stress-activated RNA cleavage pathways; Las1 plays a fundamental role in processing pre-rRNA. Underscoring the significance of Las1 function in the cell, mutations in the human LAS1L (LAS1-like) gene have been associated with neurological dysfunction. Two juxtaposed HEPN nuclease motifs create Las1's composite nuclease active site, but the roles of the individual HEPN motif residues are poorly defined. Here using a combination of in vivo experiments in Saccharomyces cerevisiae and in vitro assays, we show that both HEPN nuclease motifs are required for Las1 nuclease activity and fidelity. Through in-depth sequence analysis and systematic mutagenesis, we determined the consensus HEPN motif in the Las1 subfamily and uncovered its canonical and specialized elements. Using reconstituted Las1 HEPN-HEPN' chimeras, we defined the molecular requirements for RNA cleavage. Intriguingly, both copies of the Las1 HEPN motif were important for nuclease function, revealing that both HEPN motifs participate in coordinating the RNA within the Las1 active site. We also established that conformational flexibility of the two HEPN domains is important for proper nuclease function. The results of our work reveal critical information about how dual HEPN domains come together to drive Las1-mediated RNA cleavage.

(Carnegie Mellon University) A new study sought to determine how the impact of recommender systems (also called recommenders) is affected by factors such as product type, attributes, and other sources of information about products on retailers' websites. The study found that recommenders increased the number of consumer views of product pages as well as the number of products consumers consider, but that the increase was moderated by product attributes and review ratings.

(ETH Zurich) Global warming has affected the entire planet's surface, except for one particular area of the ocean, which has bucked the trend. A research team comprising scientists from ETH Zurich and Princeton University has unravelled the causes of this conundrum.

(American Geriatrics Society) The American Geriatrics Society (AGS) today announced that Ellen Flaherty, PhD, APRN, AGSF, an assistant professor at the Dartmouth Geisel School of Medicine and director of the Dartmouth Centers for Health & Aging, will deliver the society's prestigious Henderson State-of-the-Art Lecture. Dr. Flaherty will deliver her talk, Leveraging the Potential of Interprofessional Teams in Primary Care Practice, at the AGS 2021 Annual Scientific Meeting (#AGS21) in Chicago, Ill. (May 12-15, 2021).

(University of Sydney) Data centres and digital information processors are reaching their capacity limits and producing heat. Foundational work here on optical-acoustic microchips opens door to low-heat, low-energy, fast internet.

Closing 2019, reggae star Buju Banton celebrated the inking of a partnership deal with international entertainment group Roc Nation, founded by rapper Jay-Z. The artiste is on the promotional pathway for his 2020 album, Upside Down, which will be...

In an interview with THE STAR last August, up-and-coming artiste Bad Gyal Jade dubbed herself the 'female Kartel'. Drawing comparisons between her style and flow and that of the incarcerated deejay, Jade said the label was a fitting one. Though...

Having to witness your child go off to bed without a meal is not the most pleasing experience for a parent. However, this is the reality of Viviene Francis, who was laid off from her job as a bartender. Francis, who is a single mother, told THE...

A Manchester mother is pleading with the authorities to provide her with the results of COVID-19 tests done on her and her week-old baby. The woman claims that she has been in isolation in hospital since April 27, a day after she gave birth to...

Data from March shows similarities in spending across various demographics.

Businesses will benefit from clear policy guidance from lawmakers

Members Event

Event participants

Michelle Bachelet, United Nations High Commissioner for Human Rights

Chair: Ruma Mandal, Head, International Law Programme, Chatham House

Fatty acid esters of hydroxy fatty acids (FAHFAs) are a newly discovered class of signaling lipids with anti-inflammatory and anti-diabetic properties. However, the endogenous regulation of FAHFAs remains a pressing but unanswered question. Here, using MS-based FAHFA hydrolysis assays, LC-MS–based lipidomics analyses, and activity-based protein profiling, we found that androgen-induced gene 1 (AIG1) and androgen-dependent TFPI-regulating protein (ADTRP), two threonine hydrolases, control FAHFA levels in vivo in both genetic and pharmacologic mouse models. Tissues from mice lacking ADTRP (Adtrp-KO), or both AIG1 and ADTRP (DKO) had higher concentrations of FAHFAs particularly isomers with the ester bond at the 9th carbon due to decreased FAHFA hydrolysis activity. The levels of other lipid classes were unaltered indicating that AIG1 and ADTRP specifically hydrolyze FAHFAs. Complementing these genetic studies, we also identified a dual AIG1/ADTRP inhibitor, ABD-110207, which is active in vivo. Acute treatment of WT mice with ABD-110207 resulted in elevated FAHFA levels, further supporting the notion that AIG1 and ADTRP activity control endogenous FAHFA levels. However, loss of AIG1/ADTRP did not mimic the changes associated with pharmacologically administered FAHFAs on extent of upregulation of FAHFA levels, glucose tolerance, or insulin sensitivity in mice, indicating that therapeutic strategies should weigh more on FAHFA administration. Together, these findings identify AIG1 and ADTRP as the first endogenous FAHFA hydrolases identified and provide critical genetic and chemical tools for further characterization of these enzymes and endogenous FAHFAs to unravel their physiological functions and roles in health and disease.

Elena Lorente
Apr 7, 2020; 0:RA120.002014v1-mcp.RA120.002014
Research

Eelke P. Béguin
Apr 24, 2020; 0:RA120.001964v1-mcp.RA120.001964
Research

Tatjana Goebel
Apr 16, 2020; 0:RA120.001983v1-mcp.RA120.001983
Research

Liye Chen
May 1, 2020; 19:871-883
Research

Lindsay K Pino
Apr 20, 2020; 0:P119.001913v1-mcp.P119.001913
Perspective

Payman Samavarchi-Tehrani
May 1, 2020; 19:757-773
Review

In this blog by Julianne Vega, graduate student at University of Kentucky, Julianne tells us how to make the most of attending math conferences. If you are heading to a conference, challenge yourself! Your first conference may not be the … Continue reading →

Research Event

Event participants

Ahmed Tabaqchali, Chief Investment Officer, Asia Frontier Capital Iraq Fund; Adjunct Assistant Professor, American University of Iraq Sulaimani
Moderator: Renad Mansour, Senior Research Fellow, Middle East and North Africa Programme, Chatham House

Purpose: ⁶⁸Ga-DOTA-JR11 is an antagonist for somatostatin receptor used in neuroendocrine imaging. The purpose of this study is to compare ⁶⁸Ga-DOTA-JR11 and ⁶⁸Ga-DOTATATE PET/CT in patients with metastatic, well-differentiated neuroendocrine tumors. Methods: Patients with histologically-proven, metastatic and/or unresectable, well-differentiated neuroendocrine tumors were prospectively recruited in this study. They received an intravenous injection of ⁶⁸Ga-DOTATATE (4.0 ± 1.3 mCi) on the first day and ⁶⁸Ga-DOTA-JR11 (4.0 ± 1.4 mCi) on the second day. Whole-body PET/CT scans were performed at 40 to 60 minutes after injection on the same scanner. Physiologic uptake of normal organs, lesion numbers, and lesion uptake were compared. Results: Twenty-nine patients were prospectively enrolled in the study. The SUV_max of the spleen, renal cortex, adrenal glands, pituitary glands, stomach wall, normal liver parenchyma, small intestine, pancreas, and bone marrow were significantly lower on ⁶⁸Ga-DOTA-JR11 than on ⁶⁸Ga-DOTATATE PET/CT (P<0.001). ⁶⁸Ga-DOTA-JR11 detected significantly more liver lesions (539 vs. 356, P = 0.002), but fewer bone lesions (156 vs. 374, P = 0.031, Figure 3) than ⁶⁸Ga-DOTATATE. The tumor-to-background ratio of liver lesions was significantly higher on ⁶⁸Ga-DOTA-JR11 (7.6 ± 5.1 vs. 3.4 ± 2.0, P<0.001). ⁶⁸Ga-DOTA-JR11 and ⁶⁸Ga-DOTATATE PET/CT showed comparable results for primary tumors and lymph node metastases based on either patient-based or lesion-based comparison. Conclusion: ⁶⁸Ga-DOTA-JR11 performs better in the detection ability and TBR of liver metastases. However, ⁶⁸Ga-DOTATATE outperforms ⁶⁸Ga-DOTA-JR11 in the detection of bone metastases. The differential affinity of different metastatic sites provides key information for patient selection in imaging and peptide receptor radionuclide therapy.

Purpose: Although the incidence of de novo neuroendocrine prostate cancer (NEPC) is rare, recent data suggests that low expression of prostate-specific membrane antigen (PSMA) is associated with a spectrum of neuroendocrine (NE) hallmarks and androgen receptor (AR)-suppression in prostate cancer (PC). Previous clinical reports indicate that PCs with a phenotype similar to NE tumors can be more amenable to imaging by ¹⁸F-Fluorodeoxyglucose (FDG) rather than PSMA-targeting radioligands. In this study, we evaluated the association between NE gene signature and FDG uptake-associated genes including glucose transporters (GLUTs) and hexokinases, with the goal of providing a genomic signature to explain the reported FDG-avidity of PSMA-suppressed tumors. Methods: Data mining approaches, cell lines and patient-derived xenograft (PDX) models were used to study the levels of 14 members of the SLC2A family (encoding GLUT proteins), 4 members of the hexokinase family (genes: HK1 to 3 and GCK) and PSMA (FOLH1 gene) following AR-inhibition and in correlation with NE hallmarks. Also, we characterize a NE-like PC (NELPC) subset among a cohort of primary and metastatic PC samples with no NE histopathology. We measured glucose uptake in a NE-induced in vitro model and a zebrafish model by non-radioactive imaging of glucose uptake using fluorescent glucose bioprobe, GB2-Cy3. Results: This work demonstrates that a NE gene signature associates with differential expression of genes encoding GLUT and hexokinase proteins. In NELPC, elevated expression of GCK (encoding glucokinase protein) and decreased expression of SLC2A12 correlated with earlier biochemical recurrence. In tumors treated with AR-inhibitors, high expression of GCK and low expression of SLC2A12 correlated with NE histopathology and PSMA gene suppression. GLUT12-suppression and amplification of glucokinase was observed in NE-induced PC cell lines and PDX models. A higher glucose uptake was confirmed in low-PSMA tumors using a GB2-Cy3 probe in a zebrafish model. Conclusion: NE gene signature in NEPC and NELPC associates with a distinct transcriptional profile of GLUTs and HKs. PSMA-suppression correlates with GLUT12-suppression and glucokinase-amplification. Alteration of FDG uptake-associated genes correlated positively with higher glucose uptake in AR and PSMA-suppressed tumors. Zebrafish xenograft tumor models are an accurate and efficient pre-clinical method for monitoring non-radioactive glucose uptake.

We performed post-hoc analyses on the utility of pre-therapeutic and early interim ⁶⁸Ga-DOTA-Tyr3-octreotide (⁶⁸Ga-DOTATOC) positron emission tomography (PET) tumor uptake and volumetric parameters and a recently proposed biomarker, the inflammation-based index (IBI), for peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumor (NET) patients treated with ⁹⁰Y-DOTATOC in the setting of a prospective phase II trial. Methods: Forty-three NET patients received up to four cycles of 1.85 GBq/m²/cycle ⁹⁰Y-DOTATOC with a maximal kidney biologic effective dose of 37 Gy. All patients underwent a ⁶⁸Ga-DOTATOC PET/computed tomography (CT) at baseline and seven weeks after the first PRRT cycle. ⁶⁸Ga-DOTATOC-avid tumor lesions were semi-automatically delineated using a customized standardized uptake value (SUV) threshold-based approach. PRRT response was assessed on CT using RECIST 1.1. Results: Median progression-free survival (PFS) and overall survival (OS) were 13.9 and 22.3 months, respectively. An SUVmean higher than 13.7 (75th percentile (P75)) was associated with better survival (hazard ratio (HR) 0.45; P = 0.024), whereas a ⁶⁸Ga-DOTATOC-avid tumor volume higher than 578 ml (P75) was associated with worse OS (HR 2.18; P = 0.037). Elevated baseline IBI was associated with worse OS (HR 3.90; P = 0.001). Multivariate analysis corroborated independent associations between OS and SUVmean (P = 0.016) and IBI (P = 0.015). No significant correlations with PFS were found. A composite score based on SUVmean and IBI allowed to further stratify patients in three categories with significantly different survival. On early interim PET, a decrease in SUVmean of more than 17% (P75) was associated with worse survival (HR 2.29; P = 0.024). Conclusion: Normal baseline IBI and high ⁶⁸Ga-DOTATOC tumor uptake predict better outcome in NET patients treated with ⁹⁰Y-DOTATOC. This can be used for treatment personalization. Interim ⁶⁸Ga-DOTATOC PET does not provide information for treatment personalization.

⁶⁸Ga-DOTATOC-PET/MRI (⁶⁸Gallium-DOTATOC-positron emission tomography/magnetic resonance imaging) combines the advantages of PET in the acquisition of metabolic-functional information with the high soft tissue contrast of MRI. Standardized uptake values (SUV) in tumors were suggested as a measure of somatostatin receptor expression. A challenge with receptor ligands is, that the distribution volume is confined to tissues with tracer-uptake, potentially limiting SUV quantification. In this study, different functional, three-dimensional (3D) SUV, apparent diffusion coefficient (ADC) parameters and arterial tumor enhancement were tested for the characterization of gastroendopancreatic neuroendocrine tumors (GEP-NET). Methods: For this single-center, cross-sectional study, 22 patients with 24 histologically confirmed GEP-NET lesions (15 men/7 women; median, 61 years, range, 43-81 years), who received hybrid ⁶⁸Ga-DOTA-PET/MRI examinations at 3T between January 2017 and July 2019 met eligibility criteria. SUVs, tumor-to-background ratios (TBR), the total functional tumor volume (TFTV), ADCmean and ADCmin were measured based on volumes of interest (VOI) and examined with receiver operating characteristic analysis to determine cut-off values for differentiation between low and intermediate grade GEP-NET. Spearman’s rank correlation coefficients were used to assess correlations between functional imaging parameters. Results: The ratio of PET-derived SUVmean and diffusion-weighted imaging (DWI)-derived ADCmin was introduced as a combined variable to predict tumor grade, outperforming single predictors. Based on a threshold ratio of 0.03 to be exceeded, tumors could be classified as grade 2 with a sensitivity of 86% and specificity of 100%. SUV and functional ADC values as well as arterial contrast enhancement parameters showed non-significant and mostly negligible correlations. Conclusion: As receptor density and tumor cellularity appear to be independent, potentially complementary phenomena, the combined PET/MRI ratio SUVmean/ADCmin may be used as a novel biomarker, allowing to differentiate between grade 1 and 2 GEP-NET.

Triple negative breast cancer (TNBC) remains the most aggressive subtype of breast cancer leading to the worst prognosis. Because current therapeutic approaches lack efficacy, there is a clinically unmet need for effective treatment alternatives. Herein, we demonstrate a promising strategy utilizing a tumor-targeting alkylphosphocholine (NM600) radiolabeled with ¹⁷⁷Lu for targeted radionuclide therapy (TRT) of TNBC. In two murine syngeneic models of TNBC, we confirmed excellent tumor targeting and rapid normal tissue clearance of the PET imaging analog ⁸⁶Y-NM600. Based on longitudinal PET/CT data acquired with ⁸⁶Y-NM600, we estimated the dosimetry of therapeutic ¹⁷⁷Lu-NM600, which showed larger absorbed doses in the tumor compared to normal tissues. Administration of ¹⁷⁷Lu-NM600 resulted in significant tumor growth inhibition and prolonged overall survival in mice bearing syngeneic 4T07 and 4T1 tumors. Complete response was attained in 60% of 4T07 bearing mice, but animals carrying aggressive 4T1 tumor grafts succumbed to metastatic progression. The injected activities used for treatment (9.25 and 18.5 MBq) were well tolerated, and only mild transient cytopenia was noted. Overall, our results suggest that ¹⁷⁷Lu-NM600 TRT has potential for treatment of TNBC and merits further exploration in a clinical setting.

Rationale: The presence of metastasis in local lymph nodes (LNs) is a key factor influencing choice of therapy and prognosis in cervical and endometrial cancers; therefore, the exploration of sentinel LNs (SLNs) is highly important. Currently, however, SLN mapping requires LN biopsy for pathologic evaluation, since there are no clinical imaging approaches that can identify tumor-positive LNs in early stages. Staging lymphadenectomy poses risks, such as leg lymphedema or lymphocyst formation. Furthermore, in 80% to 90% of patients, the explored LNs are ultimately tumor free, meaning the vast majority of patients are unnecessarily subjected to lymphadenectomy. Methods: Current lymphoscintigraphy methods only identify the anatomic location of the SLNs but do not provide information on their tumor status. There are no non-invasive methods to reliably identify metastases in LNs before surgery. We have developed positron lymphography (PLG), a method to detect tumor-positive LNs, where ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) is injected interstitially into the uterine cervix the day of surgery, and its rapid transport through the lymphatic vessels to the SLN is then visualized with dynamic positron emission tomography/computed tomography (PET/CT). We previously showed that PLG was able to identify metastatic LNs in animal models. Here, we present the first results from our pilot clinical trial (clinical trials identifier NCT02285192) in 23 patients with uterine or cervical cancer. On the morning of surgery, ¹⁸F-FDG was injected into the cervix, followed by an immediate dynamic PET/CT scan of the pelvis and a delayed 1-h whole body scan. Results: There were 3 (15%) node-positive cases on final pathologic analysis, and all LNs (including one with a focus of only 80 tumor cells) were identified by PLG except one node with an 11-mm micrometastasis. There were 2 (10%) false-positive cases with PLG, in which final pathology of the corresponding SLNs was negative for tumor. Methods: Current lymphoscintigraphy methods only identify the anatomic location of the SLNs but do not provide information on their tumor status. There are no non-invasive methods to reliably identify metastases in LNs before surgery. We have developed positron lymphography (PLG), a method to detect tumor-positive LNs, where ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) is injected interstitially into the uterine cervix the day of surgery, and its rapid transport through the lymphatic vessels to the SLN is then visualized with dynamic positron emission tomography/computed tomography (PET/CT). We previously showed that PLG was able to identify metastatic LNs in animal models. Here, we present the first results from our pilot clinical trial (clinical trials identifier NCT02285192) in 23 patients with uterine or cervical cancer. On the morning of surgery, ¹⁸F-FDG was injected into the cervix, followed by an immediate dynamic PET/CT scan of the pelvis and a delayed 1-h whole body scan. Results: There were 3 (15%) node-positive cases on final pathologic analysis, and all LNs (including one with a focus of only 80 tumor cells) were identified by PLG, except for one node with an 11-mm micrometastasis. There were 2 (10%) false-positive cases with PLG, in which final pathology of the corresponding SLNs was negative for tumor. Conclusion: This first-in-human study of PLG in women with uterine and cervical cancer demonstrates its feasibility and its ability to identify patients with nodal metastases, and warrants further evaluation in additional studies.

Rationale: The treatment of choice for insulinomas and focal lesions in congenital hyperinsulinism (CHI) is surgery. However, intra-operative detection can be challenging. This could be overcome with intra-operative fluorescence imaging, which provides real-time lesion detection with a high spatial resolution. Here, a novel method for targeted near-infrared (NIR) fluorescence imaging of glucagon-like peptide 1 receptor (GLP-1R) positive lesions, using the GLP-1 agonist exendin-4, labeled with IRDye800CW, was examined in vitro and in vivo. Methods: A competitive binding assay was performed using Chinese hamster lung (CHL) cells transfected with the GLP-1R. Tracer biodistribution was determined in BALB/c nude mice bearing subcutaneous CHL-GLP-1R xenografts. In vivo NIR fluorescence imaging of CHL-GLP-1R xenografts was performed. Localization of the tracer in the pancreatic islets of BALB/c nude mice was examined using fluorescence microscopy. Laparoscopic imaging was performed to detect the fluorescent signal of the tracer in the pancreas of mini pigs. Results: Exendin-4-IRDye800CW binds the GLP-1R with an IC50 value of 3.96 nM. The tracer accumulates in CHL-GLP-1R xenografts. Subcutaneous CHL-GLP-1R xenografts were visualized using in vivo NIR fluorescence imaging. The tracer accumulates specifically in the pancreatic islets of mice and a clear fluorescent signal was detected in the pancreas of mini pigs. Conclusion: These date provide the first in vivo evidence of the feasibility of targeted fluorescence imaging of GLP-1R positive lesions. Intra-operative lesion delineation using exendin-4-IRDye800CW could benefit open as well as laparoscopic surgical procedures for removal of insulinomas and focal lesions in CHI.

Studies demonstrate that the investigational ⁶⁴Cu-DOTATATE radiopharmaceutical may provide diagnostic and logistical benefits over available imaging agents for patients with somatostatin receptor (SSTR)-positive neuroendocrine tumors (NETs). Accordingly, we aimed to prospectively determine the lowest dose of ⁶⁴Cu-DOTATATE that facilitates diagnostic quality scans and evaluated the diagnostic performance and safety in a phase III study of patients with SSTR-expressing NETs. Methods: A dose-ranging study was conducted in 12 patients divided into 3 dose groups (111 MBq [3.0 mCi], 148 MBq [4.0 mCi], and 185 MBq [5.0 mCi] ± 10%) to determine the lowest dose of ⁶⁴Cu-DOTATATE that produced diagnostic quality PET/CT images. Using the ⁶⁴Cu-DOTATATE dose identified in the dose-ranging study, 3 independent nuclear medicine physicians who were blinded to all clinical information read PET/CT scans from 21 healthy volunteers and 42 NET-positive patients to determine those with "Disease" and "No Disease," as well as "Localized" versus "Metastatic" status. Blinded-reader evaluations were compared to a patient-specific standard of truth (SOT), which was established by an independent oncologist who used all previously available pathology, clinical, and conventional imaging data. Diagnostic performance calculated for ⁶⁴Cu-DOTATATE included sensitivity, specificity, negative predictive value, positive predictive value, and accuracy. Inter- and intra-reader reliability, as well as ability to differentiate between localized and metastatic disease, was also determined. Adverse events (AEs) were recorded from ⁶⁴Cu-DOTATATE injection through 48 hours post-injection. Results: The dose-ranging study identified 148 MBq (4.0 mCi) as the optimal dose to obtain diagnostic quality PET/CT images. Following database lock, diagnostic performance from an initial majority read of the 3 independent readers showed a significant 90.9% sensitivity (P = 0.0042) and 96.6% specificity (P < 0.0001) for detecting NETs, which translated to a 100.0% sensitivity and 96.8% specificity after correcting for an initial SOT misread. Excellent inter- and intra-reader reliability, as well as ability to distinguish between localized and metastatic disease, was also noted. No AEs were related to ⁶⁴Cu-DOTATATE, and no serious AEs were observed. Conclusion: ⁶⁴Cu-DOTATATE PET/CT is a safe imaging technique that provides high-quality and accurate images at a dose of 148 MBq (4.0 mCi) for the detection of somatostatin-expressing NETs.

Galectins are carbohydrate-binding proteins overexpressed in bladder cancer (BCa) cells. Dendritic galactose moieties have a high affinity for galectin-expressing tumor cells. We radiolabeled a dendritic galactose carbohydrate with fluorine-18 – ¹⁸F-labeled galactodendritic unit 4 – and examined its potential in imaging urothelial malignancies. Methods: The ¹⁸F-labeled 1st generation galactodendritic unit 4 was obtained from its tosylate precursor. We conducted in vivo studies in galectin-expressing UMUC3 orthotopic BCa model to determine the ability of ¹⁸F-labeled galactodendritic unit 4 to image BCa. Results: Intravesical administration of ¹⁸F-labeled galactodendritic unit 4 allowed specific accumulation of the carbohydrate radiotracer in galectin-1 overexpressing UMUC3 orthotopic tumors when imaged with PET. The ¹⁸F-labeled galactodendritic unit 4 was not found to accumulate in non-tumor murine bladders. Conclusion: The ¹⁸F-labeled galactodendritic unit 4 and similar analogs may be clinically relevant and exploitable for PET imaging of galectin-1 overexpressing bladder tumors.

Overexpression of somatostatin receptors in patients with neuroendocrine neoplasms (NEN) is utilized for both diagnosis and treatment. Receptor density may reflect tumor differentiation and thus be associated with prognosis. Non-invasive visualization and quantification of somatostatin receptor density is possible by somatostatin receptor imaging (SRI) using positron emission tomography (PET). Recently, we introduced ⁶⁴Cu-DOTATATE for SRI and we hypothesized that uptake of this tracer could be associated with overall (OS) and progression-free survival (PFS). Methods: We evaluated patients with NEN that had a ⁶⁴Cu-DOTATATE PET/CT SRI performed in two prospective studies. Tracer uptake was determined as the maximal standardized uptake value (SUV_max) for each patient. Kaplan-Meier analysis with log-rank was used to determine the predictive value of ⁶⁴Cu-DOTATATE SUV_max for OS and PFS. Specificity, sensitivity and accuracy was calculated for prediction of outcome at 24 months after ⁶⁴Cu-DOTATATE PET/CT. Results: A total of 128 patients with NEN were included and followed for a median of 73 (1-112) months. During follow-up, 112 experienced disease progression and 69 patients died. The optimal cutoff for ⁶⁴Cu-DOTATATE SUV_max was 43.3 for prediction of PFS with a hazard ratio of 0.56 (95% CI: 0.38-0.84) for patients with SUV_max > 43.3. However, no significant cutoff was found for prediction of OS. In multiple Cox regression adjusted for age, sex, primary tumor site and tumor grade, the SUV_max cutoff hazard ratio was 0.50 (0.32-0.77) for PFS. The accuracy was moderate for predicting PFS (57%) at 24 months after ⁶⁴Cu-DOTATATE PET/CT. Conclusion: In this first study to report the association of ⁶⁴Cu-DOTATATE PET/CT and outcome in patients with NEN, tumor somatostatin receptor density visualized with ⁶⁴Cu-DOTATATE PET/CT was prognostic for PFS but not OS. However, the accuracy of prediction of PFS at 24 months after ⁶⁴Cu-DOTATATE PET/CT SRI was moderate limiting the value on an individual patient basis.

Background: Radiopharmaceutical dosimetry depends on the localization in space and time of radioactive sources and requires the estimation of the amount of energy emitted by the sources deposited within targets. In particular, when computing resources are not accessible, this task can be carried out using precomputed tables of Specific Absorbed Fractions (SAFs) or S values based on dosimetric models. The OpenDose collaboration aims to generate and make freely available a range of dosimetric data and tools. Methods: OpenDose brings together resources and expertise from 18 international teams to produce and compare traceable dosimetric data using 6 of the most popular Monte Carlo codes in radiation transport (EGSnrc/EGS++, FLUKA, GATE, Geant4, MCNP/MCNPX and PENELOPE). SAFs are uploaded, together with their associated statistical uncertainties, in a relational database. S values are then calculated from mono-energetic SAFs, based on the radioisotope decay data presented in the International Commission on Radiological Protection (ICRP) publication 107. Results: The OpenDose collaboration produced SAFs for all source regions and targets combinations of the two ICRP 110 adult reference models. SAFs computed from the different Monte Carlo codes were in good agreement at all energies, with standard deviations below individual statistical uncertainties. Calculated S values were in good agreement with OLINDA 2 (commercial) and IDAC 2.1 (free) software. A dedicated website (www.opendose.org) has been developed to provide easy and open access to all data. Conclusion: The OpenDose website allows the display and download of SAFs and the corresponding S values for 1252 radionuclides. The OpenDose collaboration, open to new research teams, will extend data production to other dosimetric models and implement new free features, such as online dosimetric tools and patient-specific absorbed dose calculation software, together with educational resources.

The objective of this retrospective study was to determine the role of ¹⁸F-FDG PET/CT in a large cohort of 495 patients with metastatic neuroendocrine neoplasms (NENs) who were treated with peptide receptor radionuclide therapy (PRRT) with a long-term follow-up. Methods: The 495 patients were treated with ¹⁷⁷Lu- and/or ⁹⁰Y- DOTATOC/DOTATATE PRRT between 2/2002 and 7/2018. All subjects received both ⁶⁸Ga-DOTATOC/TATE/NOC and ¹⁸F-FDG PET/CT prior to treatment and were followed 3-189 months. Kaplan-Meier analysis, log-rank test (Mantel-Cox), and Cox regression analysis were performed for overall survival (OS) and progression-free survival (PFS). Results: 199 patients (40.2%) presented with pancreatic NEN, 49 with CUP (cancer of unknown primary), 139 with midgut NEN, whereas the primary tumor was present in the rectum in 20, in the lung in 38, in the stomach in 8 and other locations in 42 patients. FDG-PET/CT was positive in 382 (77.2%) patients and 113 (22.8%) were FDG-negative before PRRT, while 100% were ⁶⁸Ga-DOTATOC/TATE/NOC positive. For all patients, the median PFS and OS, defined from start of PRRT, were 19.6 mo and 58.7 mo, respectively. Positive FDG predicted shorter PFS (18.5 mo vs 24.1 mo; P = 0.0015) and OS (53.2 mo vs 83.1 mo; P < 0.001) than negative FDG. Amongst the pancreatic NEN, the median OS was 52.8 mo in FDG positive and 114.3 mo in FDG negative subjects (P = 0.0006). For all patients with positive ¹⁸F-FDG uptake, and a ratio of the highest SUV_max on ⁶⁸Ga-SSTR PET to the most ¹⁸F-FDG-avid tumor lesions >2, the median OS was 53.0 mo, compared to 43.4 mo in those patients with a ratio <2 (P = 0.030). For patients with no ¹⁸F-FDG uptake (complete "mismatch" imaging pattern), the median OS was 108.3 mo vs 76.9 mo for SUV_max >15.0 and ≤15.0 on ⁶⁸Ga-SSTR PET/CT, respectively. Conclusion: The presence of positive lesions on ¹⁸F-FDG PET is an independent prognostic factor in patients with NEN treated with PRRT. Metabolic imaging with ¹⁸F-FDG PET/CT compliments the molecular imaging aspect of ⁶⁸Ga-SSTR PET/CT for the prognosis of survival after PRRT. High SSTR expression combined with negative ¹⁸F-FDG PET/CT imaging is associated with the most favorable long-term prognosis.

Introduction: Neuroendocrine differentiation is associated with treatment failure and poor outcome in metastatic castration-resistant prostate cancer (mCRPC). We investigated the effect of circulating neuroendocrine biomarkers on the efficacy of PSMA-targeted radioligand therapy (RLT). Methods: Neuroendocrine biomarker profiles (progastrin-releasing peptide, neuron-specific enolase, and chromogranin-A) were analyzed in 50 patients commencing ¹⁷⁷Lu-PSMA-617 RLT. The primary endpoint was PSA response in relation to baseline neuroendocrine marker profiles. Additional endpoints included progression-free survival. Tumor uptake on post-therapeutic scans, a known predictive marker for response, was used as control-variable. Results: Neuroendocrine biomarker profiles were abnormal in the majority of patients. Neuroendocrine biomarker levels did not predict treatment failure or early progression (P ≥ 0.13). By contrast, intense PSMA-ligand uptake in metastases predicted both treatment response (P = 0.0030) and reduced risk of early progression (P = 0.0111). Conclusion: Neuroendocrine marker profiles do not predict adverse outcome of RLT. By contrast, high ligand uptake was confirmed to be crucial for achieving tumor-response.

Rationale: Fluorescence molecular endoscopy (FME) is an emerging technique that has the potential to improve the 22% colorectal polyp detection miss-rate. We determined the optimal dose-to-imaging interval and safety of FME using EMI-137, a c-Met targeted fluorescent peptide, in a population at high-risk for colorectal cancer. Methods: We performed in vivo FME and quantification of fluorescence by multi-diameter single-fiber reflectance, single-fiber fluorescence spectroscopy in 15 patients with a dysplastic colorectal adenoma. EMI-137 was intravenously administered (0.13mg/kg) at a one-, two- or three-hour dose-to-imaging interval (N = 3 patients per cohort). Two cohorts were expanded to six patients based on target-to-background ratios (TBR). Fluorescence was correlated to histopathology and c-Met expression. EMI-137 binding specificity was assessed by fluorescence microscopy and in vitro experiments. Results: FME using EMI-137 appeared to be safe and well tolerated. All dose-to-imaging intervals showed significantly increased fluorescence in the colorectal lesions compared to surrounding tissue, with a TBR of 1.53, 1.66 and 1.74 respectively (mean intrinsic fluorescence (Q·μ^f_a,x) = 0.035 vs. 0.023mm^-1, P<0.0003; 0.034 vs. 0.021mm^-1, P<0.0001; 0.033 vs. 0.019mm^-1, P<0.0001). Fluorescence correlated to histopathology on a macroscopic and microscopic level, with significant c-Met overexpression in dysplastic mucosa. In vitro, a dose-dependent specific binding was confirmed. Conclusion: FME using EMI-137 appeared to be safe and feasible within a one-to-three hour dose-to-imaging interval. No clinically significant differences were observed between the cohorts, although a one-hour dose-to-imaging interval was preferred from a clinical perspective. Future studies will investigate EMI-137 for improved colorectal polyp detection during screening colonoscopies.

The value of interim ¹⁸F-fluorodeoxyglucose positron emission tomography (iPET) guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the deltaSUV_max (SUV_max) approach – two methods to assess early metabolic response to standard chemotherapy in DLBCL. Methods: Of 609 DLBCL patients participating in the Positron Emission Tomography-guided Therapy of Aggressive non-Hodgkin Lymphomas (PETAL) trial, iPET scans of 596 patients originally evaluated using the SUV_max method were available for post-hoc assessment of the Deauville score. A commonly used definition of an unfavorable iPET result according to the Deauville score is an uptake greater than that of the liver, whereas an unfavorable iPET scan with regard to the SUV_max approach is characterized as a relative reduction of the maximum standardized uptake value between baseline and iPET staging of less than or equal to 66%. We investigated the two methods’ correlation and concordance by Spearman’s rank correlation coefficient and the agreement in classification, respectively. We further used Kaplan-Meier curves and Cox regression to assess differences in survival between patient subgroups defined by the pre-specified cut-offs. Time-dependent receiver operating curve analysis provided information on the methods’ respective discrimination performance. Results: Deauville score and SUV_max approach differed in their iPET-based prognosis. The SUV_max approach outperformed the Deauville score in terms of discrimination performance – most likely due to a high number of false-positive decisions by the Deauville score. Cut-off-independent discrimination performance remained low for both methods, but cut-off-related analyses showed promising results. Both favored the SUV_max approach, e.g. for the segregation by iPET response, where the event-free survival hazard ratio was 3.14 (95% confidence interval (CI): 2.22 – 4.46) for SUV_max and 1.70 (95% CI: 1.29 – 2.24) for the Deauville score. Conclusion: When considering treatment intensification, the currently used Deauville score cut-off of an uptake above that of the liver seems to be inappropriate and associated with potential harm for DLBCL patients. The SUV_max criterion of a relative reduction of the maximum standardized uptake value of less than or equal to 66% should be considered as an alternative.

Invitation Only Research Event

Event participants

Professor Nick Binedell, Founding Director and Sasol Chair of Strategic Management, Gordon Institute of Business Science (GIBS), University of Pretoria