Research Event

Event participants

Andrew Sullivan, President and CEO, Internet Society
Jennifer Cobbe, Research Associate, Department of Computer Science and Technology, University of Cambridge
Jesse Sowell, Assistant Professor, Department of International Affairs, Bush School of Government and Public Service, Texas A&M University
Chair: Emily Taylor, Associate Fellow, International Security, Chatham House, Editor, Journal of Cyber Policy

14 November 2019

As internet governance issues emerge in the wake of innovations such as the Internet of Things and advanced artificial intelligence, there is an urgent need for the EU and US to establish a common, positive multi-stakeholder vision for regulating and governing the internet.

16 January 2020

The aim of this project is to provide a space to explore creative/disruptive ideas in order to make headway on perspectives concerning deterrence. This will encourage ‘responsible disruption’ in the nuclear field.

This programme of work addresses the conundrum of nuclear weapons as a wicked problem in a complex adaptive system.

Research Event

Event participants

Konstantinos Komaitis, Senior Director, Policy Development & Strategy, Internet Society
Gregory Asmolov, Leverhulme Early Career Fellow Russia Institute, King’s College London
Further speakers to be announced.
Chair: Joyce Hakmeh, Senior Research Fellow, International Security Programme, Chatham House and Co-Editor of the Journal of Cyber Policy.

20 April 2020

Nuclear deterrence theory, with its roots in the Cold War era, may not account for all eventualities in the 21st century. Researchers at Chatham House have worked with eight experts to produce this collection of essays examining four contested themes in contemporary policymaking on deterrence.

Invitation Only Research Event

Invitation Only Research Event

Event participants

Dr Azzam Alwash, Founder & CEO, Nature Iraq
Peter Schwartzstein, Independent Journalist; Non-Resident Fellow, Centre for Climate Security
Discussant: Dr Jehan Baban, Founder & President, The Iraqi Environment and Health Society-UK
Chair: Dr Glada Lahn, Senior Research Fellow, Energy, Environment and Resources Department, Chatham House

Members Event

Event participants

Dr Wolfram Lacher, Senior Associate, German Institute for International and Security Affairs; Author, Libya's Fragmentation: Structure and Process in Violent Conflict
Chair: Maryam Nemazee, Anchor, Al Jazeera

Further speakers to be announced.

Invitation Only Research Event

Event participants

Abdul Rahman Alageli, Associate Fellow, MENA Programme, Chatham House
Emaddedin Badi, Non-Resident Scholar, Middle East Institute
Tim Eaton, Senior Research Fellow, MENA Programme Chatham House
Valerie Stocker, Independent Researcher

17 March 2020

This paper explores armed group–community relations in Libya and the sources of revenue that have allowed armed groups to grow in power and influence. It draws out the implications for policy and identifies options for mitigating conflict dynamics.

15 April 2020

The currently available therapeutic radiopharmaceutical for high-risk neuroblastoma, ¹³¹I-MIBG, is ineffective at targeting micrometastases due to the low linear energy transfer (LET) properties of high-energy beta particles. In contrast, Auger radiation has high-LET properties with nanometer ranges in tissue, efficiently causing DNA damage when emitted in close proximity to DNA. The aim of this study was to evaluate the cytotoxicity of targeted Auger therapy in pre-clinical models of high-risk neuroblastoma. Methods: Using a radiolabeled poly(ADP-ribose) polymerase (PARP) inhibitor, ¹²⁵I-KX1, we delivered an Auger emitter iodine-125 to PARP-1: a chromatin-binding enzyme overexpressed in neuroblastoma. In vitro cytotoxicity of ¹²⁵I-KX1 was assessed in nineteen neuroblastoma cell lines, followed by in-depth pharmacological analysis in a sensitive and resistant pair of cell lines. Immunofluorescence microscopy was used to characterize ¹²⁵I-KX1-induced DNA damage. Finally, in vitro/in vivo microdosimetry was modeled from experimentally derived pharmacological variables. Results: ¹²⁵I-KX1 was highly cytotoxic in vitro across a panel of neuroblastoma cell lines, directly causing double strand DNA breaks. Based on subcellular dosimetry, ¹²⁵I-KX1 was approximately twice as effective compared to ¹³¹I-KX1, whereas cytoplasmic ¹²⁵I-MIBG demonstrated low biological effectiveness. Despite the ability to deliver focused radiation dose to the cell nuclei, ¹²⁵I-KX1 remained less effective than its alpha-emitting analog ²¹¹At-MM4, and required significantly higher activity for equivalent in vivo efficacy based on tumor microdosimetry. Conclusion: Chromatin-targeted Auger therapy is lethal to high-risk neuroblastoma cells with potential use in micrometastatic disease. This study provides the first evidence for cellular lethality from a PARP-1 targeted Auger emitter, calling for further investigation into targeted Auger therapy.

Objective: To investigate the lesion detection rate of ¹⁸F-DCFPyL-PET/CT, a prostate-specific membrane antigen (PSMA) targeted PET agent, in biochemical relapse prostate cancer patients after primary local therapy. Methods: This is a prospective institutional review board-approved study of 90 patients with documented biochemical recurrence (median PSA 2.5 ng/mL, range 0.21-35.5 ng/mL) with negative conventional imaging after primary local therapies, including radical prostatectomy (n = 38), radiation (n = 27) or combination (n = 25). Patients on androgen deprivation therapy were excluded. Patients underwent whole-body ¹⁸F-DCFPyL-PET/CT (299.9±15.5 MBq) at 2 h p.i. PSMA-PET lesion detection rate was correlated with PSA, PSA kinetics and original primary tumor grade. Results: Seventy patients (77.8%) showed a positive PSMA-PET scan, identifying a total of 287 lesions: 37 prostate bed foci, 208 lymph nodes, and 42 bone/organ distant sites; 11 patients had a negative scan and 9 patients showed indeterminate lesions, which were considered negative in this study. The detection rates were 47.6% (n = 10/21), 50% (n = 5/10), 88.9% (n = 8/9), and 94% (n = 47/50) for PSA >0.2 to <0.5, 0.5 to <1.0, 1 to <2.0, and ≥2.0 ng/mL, respectively. In post-surgical patients, PSA, PSAdt and PSAvel correlated with PET results but the same was not true for post-radiation patients. These parameters also correlated with the extent of disease on PET (intrapelvic vs. extrapelvic). There was no significant difference between the rate of positive scans in patients with higher grade vs lower grade primary tumors (Gleason score ≥4+3 vs <3+4). Tumor recurrence was histology confirmed in 40% (28/70) of patients. On a per-patient basis, positive predictive value was 93.3% (95% CI, 77.6-99.2%) by histopathologic validation, and 96.2% (95% CI, 86.3-99.7%) by the combination of histology and imaging/clinical follow-up. Conclusion: ¹⁸F-DCFPyL-PET/CT imaging offers high detection rates in biochemically recurrent prostate cancer patients; and is positive in about 50% of patients with PSA <0.5 ng/mL, which could substantially impact clinical management. In post-surgical patients, ¹⁸F-DCFPyL-PET/CT correlates with PSA, PSAdt and PSAvel suggesting it may have prognostic value. ¹⁸F-DCFPyL-PET/CT is highly promising for localizing sites of recurrent prostate cancer.

Background: ⁶⁸Ga PSMA PET CT (PSMA) is increasingly used in men with biochemical recurrence (BCR) post radical prostatectomy (RP), but its longer term prognostic / predictive potential in these men is unknown. The aim of this study was to evaluate the predictive value of PSMA PET for 3 year freedom from progression (FFP) in men with BCR post RP undergoing salvage radiotherapy (sRT). Methods: This prospective multi-center study enrolled 260 men between 2015 and 2017. Eligible patients were referred for PSMA with rising PSA following RP. Management following PSMA was recorded but not mandated. PSMA protocols were standardised across sites and reported prospectively. Clinical, pathological and surgical information, sRT, timing and duration of androgen deprivation (ADT), 3 year PSA results and clinical events were documented. FFP was defined as a PSA rise ≤ 0.2ng/mL above nadir post sRT, with no additional treatment. Results: The median PSA was 0.26ng/mL (IQR 0.15 - 0.59) and follow-up 38 months (IQR 31-43). PSMA was negative in 34.6% (90/260), confined to prostate fossa 21.5% (56/260), pelvic nodes 26.2% (68/260), and distant disease 17.7% (46/260). 71.5% (186/260) received sRT, 38.2% (71/186) to the fossa only, 49.4% (92/186) fossa + pelvic nodes and 12.4% (23/186) nodes alone/SBRT. PSMA was highly predictive of FFP at 3 years following sRT. Overall, FFP was achieved in 64.5% (120/186) of those who received sRT, 81% (81/100) with negative/fossa confined vs. 45% (39/86) for extra fossa disease (p<0.0001). On logistic regression PSMA was more independently predictive of FFP than established clinical predictors, including PSA, T-stage, surgical margin status or Gleason score (P < 0.002). 32% of men with a negative PSMA PET did not receive treatment. Of these, 66% (19/29) progressed, with a mean rise in PSA of 1.59ng/mL over the 3 years. Conclusion: PSMA PET result is highly predictive of FFP at 3 years in men undergoing sRT for BCR following RP. In particular, men with negative PSMA PET or disease identified as still confined to the prostate fossa demonstrate high FFP, despite receiving less extensive radiotherapy and lower rates of additional ADT than those with extra fossa disease.

Objectives: Lutetium-177 (¹⁷⁷Lu)-PSMA-617 (LuPSMA) is a radioligand with high affinity for prostate specific membrane antigen (PSMA) enabling targeted beta-irradiation of prostate cancer. We have previously reported favorable activity with low toxicity in a prospective phase II trial involving 30 men with metastatic castrate-resistant prostate cancer (mCRPC). We now report their longer-term outcomes including a 20 patient extension cohort and outcomes of subsequent systemic treatments following completion of trial therapy. Methods: 50 patients with PSMA-avid mCRPC who had progressed after standard therapies received up to 4 cycles of LuPSMA every 6 weeks. Endpoints included PSA response (PCWG2), toxicity (CTCAE v4.03), imaging response, patient-reported health-related quality of life (QoL), progression-free and overall survival. We also describe, as a novel finding, outcomes of men who subsequently progressed and had further systemic therapies, including LuPSMA. Results: 75 men were screened to identify 50 patients eligible for treatment. Adverse prognostic features of the cohort included short median PSA doubling time (2.3 months) and extensive prior treatment including prior docetaxel (84%), cabazitaxel (48%), and abiraterone and/or enzalutamide (90%). The mean administered radioactivity was 7.5 GBq/cycle. PSA decline ≥ 50% was achieved in 32 of 50 patients (64%, 95% CI 50-77%), including 22 patients (44%, 95% CI 30-59%) with ≥ 80% decrease. Of 27 patients with measurable soft tissue disease, 15 (56%) achieved an objective response by RECIST 1.1. The most common toxicities attributed to LuPSMA were self-limiting G1-2 dry mouth (66%), transient G1-2 nausea (48%), G3-4 thrombocytopenia (10%) and G3 anemia (10%). Brief pain inventory severity and interference scores decreased at all time points including at the 3 month follow-up with a decrease of -1.2 (95% CI -0.5 to -1.9, P = 0.001) and 1.0 (95% CI -0.2 to -0.18, P = 0.013), respectively. At a median follow-up of 31.4 months, median OS was 13.3 months (95% CI 10.5-18.7) with a significantly longer survival of 18.4 months (95% CI 13.8-23.8) in patients achieving a PSA decline ≥ 50%. At progression following prior response, further LuPSMA was administered to 15 (30%) patients (median 2 cycles commencing 359 days from enrolment) with PSA decline ≥ 50% in 11 patients (73%). 4 of 21 patients (19%) receiving other systemic therapies upon progression experienced PSA decline ≥ 50%. There were no unexpected adverse events with LuPSMA re-treatment. Conclusion: This expanded 50 patient cohort of men with extensive prior therapy confirms our earlier report of high response rates, low toxicity and improved QoL with LuPSMA radioligand therapy. Upon progression, re-challenge LuPSMA demonstrated higher response rates than other systemic therapies.

Purpose: The aim of this retrospective multicentric study was to develop and evaluate a prognostic FDG PET/CT radiomics signature in early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic radiotherapy (SBRT). Material and Methods: Patients from 3 different centers (n = 27, 29 and 8) were pooled to constitute the training set, whereas the patients from a fourth center (n = 23) were used as the testing set. The primary endpoint was local control (LC). The primary tumour was semi-automatically delineated in the PET images using the Fuzzy locally adaptive Bayesian algorithm, and manually in the low-dose CT images. A total of 184 IBSI-compliant radiomic features were extracted. Seven clinical and treatment parameters were included. We used ComBat to harmonize radiomic features extracted from the four institutions relying on different PET/CT scanners. In the training set, variables found significant in the univariate analysis were fed into a multivariate regression model and models were built by combining independent prognostic factors. Results: Median follow-up was 21.1 (1.7 – 63.4) and 25.5 (7.7 – 57.8) months in training and testing sets respectively. In univariate analysis, none of the clinical variables, 2 PET and 2 CT features were significantly predictive of LC. The best predictive models in the training set were obtained by combining one feature from PET, namely information correlation 2 (IC2) and one from CT (Flatness), reaching a sensitivity of 100% and a specificity of 96%. Another model combining 2 PET features (IC2 and Strength), reached sensitivity of 100% and specificity of 88%, both with an undefined hazard ratio (HR) (p<0.001). The latter model obtained an accuracy of 0.91 (sensitivity 100%, specificity 81%), with a HR undefined (P = 0.023) in the testing set, however other models relying on CT radiomics features only or the combination of PET and CT features failed to validate in the testing set. Conclusion: We showed that two radiomic features derived from FDG PET were independently associated with LC in patients with NSCLC undergoing SBRT and could be combined in an accurate predictive model. This model could provide local relapse-related information and could be helpful in clinical decision-making.

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.

Due to their peculiar mechanism of action, the evaluation of radiological response to immune checkpoint inhibitors (ICI) presents many challenges in solid tumors. We aimed to compare the evaluation of first response to Nivolumab by means of CT-based criteria with respect to fluorodeoxyglucose positron emission tomography (FDG-PET) response criteria in non-small-cell lung cancer (NSCLC) patients. Methods: 72 patients with advanced NSCLC were recruited in a mono-institutional ancillary trial within the expanded access program (EAP; NCT02475382) for Nivolumab. Patients underwent CT scan and FDG-PET at baseline and after 4 cycles (first evaluation). In case of progressive disease (PD), an additional evaluation was performed after two further cycles in order to confirm progression. We evaluated the response to treatment with CT scan by means of response evaluation criteria in solid tumors (RECIST) 1.1 and Immuno-related Response Criteria (IrRC) and with FDG-PET by means of PERCIST and immunotherapy-modified-PERCIST (imPERCIST) criteria. The concordance between CT- and PET-based criteria and the capability of each method to predict overall survival (OS) were evaluated. Results: 48/72 patients were evaluable for first response assessment with both PET- and CT-based criteria. We observed low concordance between CT- and PET-based criteria (Kappa value of 0.346 and 0.355 and Kappa value of 0.128 and 0.198 between PERCIST and imPERCIST versus RECIST and irRC respectively). Looking at OS, IrRC were more reliable to distinguish responders from non-responders. However thanks to the prognostic value of partial metabolic response assessed by both PERCIST and Immuno-PERCIST, PET-based response maintained prognostic significant in patients classified as progressive disease on the basis of irRC. Conclusion: Even though the present study did not support the routine use of FDG-PET in the general population of NSCLC patients treated with ICI, it suggests the added prognostic value of the metabolic response assessment, potentially improving the therapeutic decision-making.

Purpose: To investigate differences between positron emission tomography/magnetic resonance imaging (PET/MRI) and PET/computed tomography (PET/CT) in lesion detection and classification in oncological whole-body examinations and to investigate radiation exposure differences between both modalities. Material and Methods: In this prospective, single-center, observational study 1003 oncological examinations (918 patients, mean age 57.8±14.4y) were included. Patients underwent PET/CT and subsequent PET/MRI (149.8±49.7min after tracer administration). Examinations were reviewed by radiologists and nuclear medicine physicians in consensus. Additional findings, characterization of indetermiante findings in PETCT, missed findings in PET/MRI including their clinical relevance and effective dose of both modalities were investigated. McNemar’s test was used to compare lesion detection between both hybrid imaging modalities (p<0.001 indicating statistical significance). Results: Additional information in PET/MRI was reported in 26.3% (264/1003) of examinations compared to PET/CT (p<0.001). Of these, additional malignant findings were detected in 5.3% (53/1003), leading to a change in TNM-staging in 2.9% (29/1003) due to PET/MRI. Definite lesion classification of indeterminate PET/CT findings was possible in 11.1% (111/1003) with PET/MRI. In 2.9% (29/1003), lesions detected in PET/CT were not visible in PET/MRI. Malignant lesions were missed in 1.2% (12/1003) by PET/MRI leading to a change in TNM-staging in 0.5% (5/1003). The estimated mean effective-dose for whole-body PET/CT amounted to 17.6±8.7mSv in comparison to 3.6±1.4mSv in PET/MRI, resulting in a potential dose reduction of 79.6% (p<0.001). Conclusion: PET/MRI improves lesion detection and potentially reduces additional examinations in tumor staging. Especially younger patients may benefit from the clinically relevant dose reduction of PET/MRI compared to PET/CT.

Acute myocardial infarction (MI) triggers a local and systemic inflammatory response. We recently showed microglia involvement using TSPO imaging. Here, we evaluate whether ¹¹C-methionine provides further insights into heart-brain inflammation networking. Methods: Male Bl6N mice underwent permanent coronary artery ligation followed by ¹¹C-methionine PET at 3 and 7 days (n = 3). In subgroups, leukocyte homing was blocked by integrin antibodies (n = 5). The cellular substrate for PET signal was identified using brain section immunostaining. Results: ¹¹C-methionine uptake peaked in the MI region at d3 (5.9±0.9vs 2.4±0.5 %ID/cc), decreasing to control level by d7 (4.3±0.6 %ID/cc). Brain uptake was proportional to cardiac uptake (r=0.47,p<0.05), peaking also at d3 (2.9±0.4vs 2.4±0.3 %ID/cc) and returning to baseline at d7 (2.3±0.4 %ID/cc). Integrin blockade reduced uptake at every time point. Immunostaining at d3 revealed co-localization of the L-type amino acid transporter with GFAP-positive astrocytes but not CD68-positive microglia. Conclusion: PET imaging with ¹¹C-methionine specifically identifies an astrocyte component, enabling further dissection of the heart-brain axis in post MI inflammation.

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.

Cri-Du-Chat Syndrome (CdCs) is a rare genetic disease caused by a deletion in the short arm of chromosome 5 (5p) with a variable clinical spectrum. To date no study in literature has ever investigated the alterations of brain glucose metabolism in these subjects by means of [¹⁸F]fluoro-2-deoxy-d-glucose Positron Emission Tomography/Computed Tomography (¹⁸F-FDG PET/CT). The aims of this study were to detect difference in brain FDG metabolism in patients affected by CdCs with different clinical presentations and identify possible "brain metabolic phenotypes" of this syndrome. Methods: 6 patients (age: 5 M and 1 F, age range: 10-27) with CdCs were assessed for presence of cognitive and behavioral symptoms with a battery of neuropsychological tests and then classified as patient with a severe or mild phenotype. Then, patients underwent a brain ¹⁸F-FDG PET/CT scan. PET/CT findings were compared to a control group, matched for age and sex, by using statistical parametric mapping (SPM). Association of different clinical phenotypes and ¹⁸F-FDG PET/CT findings was investigated. Results: Four patients presented a severe phenotype, whereas 2 patients demonstrated mild phenotype. SPM single subject and group analysis compared to the control cohort revealed a significant hypometabolism in the left temporal lobe (BAs 20, 36 and 38), in the right frontal subcallosal gyrus (BA 34) and caudate body, and in the cerebellar tonsils (p<0.001). Hypermetabolism (P = 0.001) was revealed in the right superior and precentral frontal gyrus (BA 6) in patient group compared to the control cohort. In SPM single subject analysis the hypermetabolic areas were detected only in patients with a severe phenotype. Conclusion: This study revealed different patterns of brain glucose metabolism in patients with severe and mild phenotype compared to control subjects. In particular, the hypermetabolic abnormalities in the brain, evaluated by¹⁸F-FDG PET/CT, seem to correlate with the severe phenotype in patients with CdCs.

The impact of prostate specific membrane antigen (PSMA) PET/CT on management of prostate cancer (PCa) patients with biochemical recurrence (BCR) is well-established. However, whether and how PSMA PET/CT affects the management of patients undergoing scans for other clinical indications remains unknown. The goal of this study was to determine the impact of ⁶⁸Ga-PSMA-11 PET/CT on initial and subsequent management decisions in a cohort of PCa patients referred for various indications ("basket trial") excluding the two main classical indications: BCR and presurgical staging. Methods: This was a prospective study of 197 patients that aimed to determine the impact of ⁶⁸Ga-PSMA-11 PET/CT on PCa stage and management. Indications for PSMA PET/CT were: initial staging of non-surgical candidates (30 patients) and re-staging after definitive treatment (n = 168). The re-staging cohort comprised: patients re-staged with known advanced metastatic disease (n = 103), after androgen deprivation therapy only (n = 16), after surgery with serum PSA levels <0.2 ng/ml (n = 13), after radiation therapy (RT) not meeting the Phoenix criteria (n = 22) and after other primary local treatments [i.e. high-intensity focused ultrasound (HIFU), focal laser ablation, cryoablation, hyperthermia or irreversible electroporation] (n = 13). Patients with BCR and candidates for curative surgery were excluded. Impact on management was assessed using pre- and post-PET questionnaires completed by referring physicians, electronic chart review and/or patient telephone encounters. Results: PSMA PET/CT changed disease stage in 135/197 (69%) patients (38% up-stage, 30% down-stage and no changes in stage in 32%). Management was affected in 104/182 (57%) patients. Specifically, PSMA PET/CT impacted management of patients who were re-staged after RT without meeting the Phoenix criteria for BCR, after other definitive local treatments and with advanced metastatic disease in 13/18 (72%), 8/12 (67%) and 59/96 (61%), respectively. Conclusion: PSMA PET/CT has a profound impact on stage and management of PCa patients outside of the two main classical indications (BCR and presurgical staging) across all examined clinical scenarios.

Rationale: The effects of tobacco smoking on the brain’s immune system are not well elucidated. While nicotine is immunosuppressive, other constituents in tobacco smoke have inflammatory effects. Positron Emission Tomography (PET) imaging of the 18-kDa translocator protein (TSPO) provide a biomarker for microglia, the brain’s primary immunocompetent cells. This work compared brain TSPO levels in 20 tobacco smokers (abstinent for at least 2 hours) and 20 nonsmokers using a fully quantitative modeling approach for the first time. Methods: [¹¹C]PBR28 PET scans were acquired with arterial blood sampling to estimate the metabolite-corrected input function. [¹¹C]PBR28 volumes of distribution (V_T) were estimated throughout the brain with multilinear analysis. Results: Statistical analyses revealed no evidence for significant differences in regional [¹¹C]PBR28 V_T between smokers and non-smokers (whole-brain Cohen’s d=0.09) despite adequate power to detect medium effect sizes. Conclusion: These findings inform previous PET studies reporting lower TSPO radiotracer concentrations in brain (measured as standardized uptake value, SUV) of tobacco smokers compared to nonsmokers by demonstrating the importance of accounting for radiotracer concentrations in plasma. These findings suggest that compared to nonsmokers, smokers have comparable TSPO levels in brain. Additional work with other biomarkers is needed to fully characterize effects of tobacco smoking on the brain’s immune system.

Purpose: PET using O-(2-[¹⁸F]Fluoroethyl)-L-tyrosine (¹⁸F-FET) is useful to detect residual tumor tissue after glioma resection. Recent animal experiments detected reactive changes of ¹⁸F-FET uptake at the rim of the resection cavity within the first two weeks after resection of gliomas. In the present study, we evaluated pre- and postoperative ¹⁸F-FET PET scans of glioma patients with particular emphasis on the identification of reactive changes after surgery. Methods: Forty-three patients with cerebral gliomas (9 low-grade, 34 high-grade; 9 primary tumors, 34 recurrent tumors) who had preoperative (time before surgery, median 23 d, range 6-44 d) and postoperative ¹⁸F-FET-PET (time after surgery, median 14, range 5–28 d) were included. PET scans (20-40 min p.i.) were evaluated visually for complete or incomplete resection (CR, IR) and compared with MRI. Changes of ¹⁸F-FET-uptake in residual tumor were evaluated by tumor-to-brain ratios (TBRmax) and in the vicinity of the resection cavity by maximum lesion-to-brain ratios (LBRmax). Results: Visual analysis of ¹⁸F-FET PET scans revealed CR in 16/43 patients and IR in the remaining patients. PET results were concordant with MRI in 69% of the patients. LBRmax of ¹⁸F-FET uptake in the vicinity of the resection cavity was significantly higher compared with preoperative values (1.59 ± 0.36 versus 1.14 ± 0.17; n = 43, p<0.001). In 11 patients (26%) a "flare phenomenon" was observed with a considerable increase of ¹⁸F-FET uptake compared with preoperative values in either the residual tumor (n = 5) or in areas remote from tumor in the preoperative PET scan (n = 6) (2.92 ± 1.24 versus 1.62 ± 0.75; p<0.001). Further follow-up in five patients showed decreasing ¹⁸F-FET uptake in the flare areas in four and progress in one case. Conclusion: Our study confirms that ¹⁸F-FET PET provides valuable information for assessing the success of glioma resection. Postoperative reactive changes at the rim of the resection cavity appear to be mild. However, in 23 % of the patients, a postoperative "flare phenomenon" was observed that warrants further investigation.

Recently, N-(4-¹⁸F-fluorobenzoyl)-interleukin-2 (¹⁸F-FB-IL2) was introduced as PET tracer for T-cell imaging. However, production is complex and time-consuming. Therefore, we developed two radiolabeled interleukin-2 (IL-2) variants, namely aluminum ¹⁸F-fluoride-(restrained complexing agent)-IL-2 (¹⁸F-AlF-RESCA-IL2) and ⁶⁸Ga-gallium-(1,4,7-triazacyclononane-4,7-diacetic acid-1-glutaric acid)-IL-2 (⁶⁸Ga-Ga-NODAGA-IL2) and compared their in-vitro and in-vivo characteristics with ¹⁸F-FB-IL2. Methods: Radiolabeling of ¹⁸F-AlF-RESCA-IL2 and ⁶⁸Ga-Ga-NODAGA-IL2 was optimized and stability was evaluated in human serum. Receptor binding was studied with activated human peripheral blood mononuclear cells (hPBMCs). Ex-vivo tracer biodistribution in immunocompetent BALB/cOlaHsd (BALB/c) mice was performed at 15, 60 and 90 min after tracer injection. In-vivo binding characteristics were studied in severe combined immune-deficient (SCID) mice inoculated with activated hPBMCs in Matrigel. Tracer was injected 15 min after hPBMCs inoculation and a 60-min dynamic PET scan was acquired, followed by ex-vivo biodistribution studies. Specific uptake was determined by co-injection of tracer with unlabeled IL2 and by evaluating uptake in a control group inoculated with Matrigel only. Results: ⁶⁸Ga-Ga-NODAGA-IL2 and ¹⁸F-AlF-RESCA-IL2 were produced with radiochemical purity >95% and radiochemical yield of 13.1±4.7% and 2.4±1.6% within 60 and 90 min, respectively. Both tracers were stable in serum, with >90% being intact tracer after 1h. In-vitro, both tracers displayed preferential binding to activated hPBMCs. Ex-vivo biodistribution studies in BALB/c mice showed higher uptake of ¹⁸F-AlF-RESCA-IL2 than ¹⁸F-FB-IL2 in liver, kidney, spleen, bone and bone marrow. ⁶⁸Ga-Ga-NODAGA-IL2 uptake in liver and kidney was higher than ¹⁸F-FB-IL2 uptake. In-vivo, all tracers revealed uptake in activated hPBMCs in SCID mice. Low uptake was seen after a blocking dose of IL2 or in the Matrigel control group. In addition, ¹⁸F-AlF-RESCA-IL2 yielded highest contrast PET images of target lymph nodes. Conclusion: Production of ¹⁸F-AlF-RESCA-IL2 and ⁶⁸Ga-Ga-NODAGA-IL2 is simpler and faster than ¹⁸F-FB-IL2. Both tracers showed good in-vitro and in-vivo characteristics with high uptake in lymphoid tissue and hPBMC xenografts.

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.

Purpose: To determine the effect of smooth filter and partial volume correction (PVC) method on measured prostate-specific membrane antigen (PSMA) activity in small metastatic lesions and to determine the impact of these changes on the molecular imaging (mi) PSMA scoring. Materials & Methods: Men with biochemical recurrence of prostate cancer with negative CT and bone scintigraphy were referred for ¹⁸F-DCFPyL PET/CT. Examinations were performed on one of 2 PET/CT scanners (GE Discovery 610 or Siemens mCT40). All suspected tumor sites were manually contoured on co-registered CT and PET images, and each was assigned a miPSMA score as per the PROMISE criteria. The PVC factors were calculated for every lesion using the anatomical CT and then applied to the unsmoothed PET images. The miPSMA scores, with and without the corrections, were compared, and a simplified "rule of thumb" (RoT) correction factor (CF) was derived for lesions at various sizes (<4mm, 4-7mm, 7-9mm, 9-12mm). This was then applied to the original dataset and miPSMA scores obtained using the RoT CF were compared to those found using the actual corrections. Results: There were 75 men (median age, 69 years; median serum PSA of 3.69 ug/L) with 232 metastatic nodes < 12 mm in diameter (mean lesion volume of 313.5 ± 309.6 mm³). Mean SUV_max before and after correction was 11.0 ± 9.3 and 28.5 ± 22.8, respectively (p<0.00001). The mean CF for lesions <4mm (n = 22), 4-7mm (n = 140), 7-9mm (n = 50), 9-12 mm (n = 20) was 4 (range: 2.5-6.4), 2.8 (range: 1.6-4.9), 2.3 (range: 1.6-3.3) and 1.8 (range 1.4-2.4), respectively. Overall miPSMA scores were concordant between the corrected dataset and RoT in 205/232 lesions (88.4%). Conclusion: There is a significant effect of smooth filter and partial volume correction on measured PSMA activity in small nodal metastases, impacting the miPSMA score.

Background: Patients with NHL who are treated with rituximab may develop resistant disease, often associated with changes in expression of CD20. The next generation β-particle emitting radioimmunoconjugate ¹⁷⁷Lu-lilotomab-satetraxetan (Betalutin®) was shown to up-regulate CD20 expression in different rituximab-sensitive NHL cell lines and to act synergistically with rituximab in a rituximab-sensitive NHL animal model. We hypothesized that ¹⁷⁷Lu-lilotomab-satetraxetan may be used to reverse rituximab-resistance in NHL. Methods: The rituximab-resistant Raji2R and the parental Raji cell lines were used. CD20 expression was measured by flow cytometry. ADCC was measured by a bioluminescence reporter assay. The efficacies of combined treatments with ¹⁷⁷Lu-lilotomab-satetraxetan (150MBq/kg or 350MBq/kg) and rituximab (4x10mg/kg) were compared with those of single agents or saline in a Raji2R-xenograft model. Cox-regression and the Bliss independence model were used to assess synergism. Results: Rituximab-binding in Raji2R cells was 36±5% of that in the rituximab-sensitive Raji cells. ¹⁷⁷Lu-lilotomab-satetraxetan treatment of Raji2R cells increased the binding to 53±3% of the parental cell line. Rituximab ADCC-induction in Raji2R cells was 20±2% of that induced in Raji cells, while treatment with ¹⁷⁷Lu-lilotomab-satetraxetan increased the ADCC-induction to 30±3% of the Raji cells, representing a 50% increase (p<0.05). The combination of rituximab with 350MBq/kg ¹⁷⁷Lu-lilotomab-satetraxetan synergistically suppressed Raji2R tumor growth in athymic Foxn1^nu mice. Conclusion: ¹⁷⁷Lu-lilotomab-satetraxetan has the potential to reverse rituximab-resistance; it increases binding and ADCC-activity in-vitro and can synergistically improve anti-tumor efficacy in-vivo.

Rationale: Neuroinflammation has been implicated in Amyotrophic Lateral Sclerosis (ALS) and can be visualized using translocator protein (TSPO) radioligands. To become a reliable pharmacodynamic biomarker for ALS multicenter trials, some challenges have to be overcome. We aimed to investigate whether multicenter data pooling of different TSPO tracers (¹¹C-PBR28 and ¹⁸F-DPA714) is feasible, after validation of an established ¹¹C-PBR28 PET pseudoreference analysis technique for ¹⁸F-DPA714. Methods: 7 ALS-Belgium (58.9±6.7 years,5M) and 8 HV-Belgium (52.1±15.2 years,3M); and 7 ALS-US (53.4±9.8 years,5M) and 7 HV-US (54.6±9.6 years,4M) from a previously published study (1) underwent dynamic ¹⁸F-DPA714 (Leuven, Belgium) or ¹¹C-PBR28 (Boston, US) PET-MR scans. For ¹⁸F-DPA714, volume of distribution (VT) maps were compared to standardized uptake value ratios (SUVR)40-60 calculated using the pseudoreference regions (1)cerebellum, (2)occipital cortex, and (3)whole brain without ventricles (WB-ventricles). Also for ¹¹C-PBR28, SUVR60-90 using WB-ventricles were calculated. Results: In line with previous studies, increased ¹⁸F-DPA714 uptake (17.0±5.6%) in primary motor cortices was observed in ALS, as measured by both VT and SUVR40-60 approaches. Highest sensitivity was found for SUVRWB-ventricles (average cluster 21.6±0.1%). ¹⁸F-DPA714 VT ratio and SUVR40-60 results were highly correlated (r>0.8, p<0.001). A similar pattern of increased uptake (average cluster 20.5±0.5%) in primary motor cortices was observed in ALS with ¹¹C-PBR28 using the SUVRWB-ventricles. Analysis of the ¹⁸F-DPA714 and ¹¹C-PBR28 data together, resulted in a more extensive pattern of significant increased glial activation in the bilateral primary motor cortices. Conclusion: The same pseudoreference region analysis technique for ¹¹C-PBR28 PET imaging can be extended towards ¹⁸F-DPA714 PET. Therefore, in ALS, standardized analysis across these two tracers enables pooling of TSPO PET data across multiple centers and increase power of TSPO as biomarker for future therapeutic trials.

McCune-Albright syndrome (MAS) is a mosaic disorder arising from gain-of-function mutations in the GNAS gene, which encodes the 3', 5'-cyclic adenosine monophosphate (cAMP) pathway-associated G-protein, Gsα. Clinical manifestations of MAS in a given individual, including fibrous dysplasia, are determined by the timing and location of the GNAS mutation during embryogenesis, the tissues involved, and the role of Gsα in the affected tissues. The Gsα mutation results in dysregulation of the cAMP signaling cascade, leading to upregulation of phosphodiesterase type 4 (PDE4), which catalyzes the hydrolysis of cAMP. Increased cAMP levels have been found in vitro in both animal models of fibrous dysplasia and in cultured cells from individuals with MAS, but not in humans with fibrous dysplasia. Positron emission tomography (PET) imaging of PDE4 with ¹¹C-(R)-rolipram has been used successfully to study the in vivo activity of the cAMP cascade. To date, it remains unknown whether fibrous dysplasia and other symptoms of MAS, including neuropsychiatric impairments, are associated with increased PDE4 activity in humans. Methods: ¹¹C-(R)-rolipram whole-body and brain PET scans were performed in six individuals with MAS (three for brain scans and six for whole-body scans) and nine healthy controls (seven for brain scans and six for whole-body scans). Results: ¹¹C-(R)-rolipram binding correlated with known locations of fibrous dysplasia in the periphery of individuals with MAS; no uptake was observed in the bones of healthy controls. In peripheral organs and the brain, no difference in ¹¹C-(R)-rolipram uptake was noted between participants with MAS and healthy controls. Conclusion: This study is the first to find evidence for increased cAMP activity in areas of fibrous dysplasia in vivo. No differences in brain uptake between MAS participants and controls were detected, which could be due to several reasons, including the limited anatomic resolution of PET. Nevertheless, the results confirm the usefulness of PET scans with ¹¹C-(R)-rolipram to indirectly measure increased cAMP pathway activation in human disease.

In randomized clinical trials (RCTs), no survival benefit has been observed for selective internal radiotherapy (SIRT) over sorafenib in patients with advanced hepatocellular carcinoma (aHCC). This study aimed to assess by means of a meta-analysis whether overall survival (OS) with SIRT, as monotherapy or followed by sorafenib, is non-inferior to sorafenib, and compare safety profiles for patients with aHCC. Methods: We searched MEDLINE, EMBASE, and the Cochrane Library up to February 2019 to identify RCTs comparing SIRT as monotherapy, or followed by sorafenib, to sorafenib monotherapy among patients with aHCC. The main outcomes were OS and frequency of treatment-related severe adverse events (AEs grade ≥3). The per-protocol population was the primary analysis population. A non-inferiority margin of 1.08 in terms of hazard ratio (HR) was pre-specified for the upper boundary of 95% confidence interval (CI) for OS. Pre-specified subgroup analyses were performed. Results: Three RCTs, involving 1,243 patients, comparing sorafenib with SIRT (SIRveNIB and SARAH) or SIRT followed by sorafenib (SORAMIC), were included. After randomization, 411/635 (64.7%) patients allocated to SIRT and 522/608 (85.8%) allocated to sorafenib completed the studies without major protocol deviations. Median OS with SIRT, whether or not followed by sorafenib, was non-inferior to sorafenib (10.2 and 9.2 months, [HR 0.91, 95% CI 0.78–1.05]). Treatment-related severe adverse events were reported in 149/515 patients (28.9%) who received SIRT and 249/575 (43.3%) who received sorafenib only (p<0.01). Conclusion: SIRT as initial therapy for aHCC is non-inferior to sorafenib in terms of OS, and offers a better safety profile.

Background: The management for totally thyroidectomized differentiated thyroid cancer (TT-DTC) patients with unexplained hyperthyroglobulinemia remains indeterminate due to evidence scarcity. This multicenter study aimed at prospectively evaluating the response to radioiodine (¹³¹I) adjuvant therapy (RAT) and its potential role in risk stratification and causal clarification. Methods: TT-DTC patients with stimulated serum thyroglobulin (Tgoff) levels > 10 ng/mL but no structurally evident disease were consecutively enrolled in five tertiary care institutions. After the administration of 5.55 GBq of ¹³¹I, the risk of presence of persistent/recurrent/metastatic DTC (prmDTC) was compared to that before RAT. The causes of hyperthyroglobulinemia were explored and the response to RAT was assessed 6-12 months post RAT. The change in suppressed thyroglobulin (Tgon) level was reported. Results: A cohort of 254 subjects with a median Tgoff of 27.1 ng/mL was enrolled for the analyses. Immediately after RAT, low-, intermediate-, and high-risk were identified in 5.9%, 88.6%, and 5.5% patients, respectively, with no significant difference in risk stratification compared with that before RAT (P = 0.952). During the follow-up (median, 10.6 months), hyperthyroglobulinemia was ultimately attributed to thyroid remnant, biochemical disease, and structural/functional disease in 17.3%, 54.3%, and 28.3% of subjects, respectively. In addition, excellent, indeterminate, biochemical incomplete, and structural/functional incomplete responses were achieved in 18.1%, 27.2%, 36.2%, and 18.5% of patients, respectively. Notably, distribution for either cause of hyperthyroglobulinemia or response to RAT was comparable among the three postoperative risk groups. Tgon levels in patients who merely received RAT declined significantly over time. Conclusion: Our study demonstrated that over 90% of TT-DTC patients with unexplained hyperthyroglobulinemia are stratified as intermediate-high risk, and RAT using 5.55 GBq of ¹³¹I reveals biochemical/functional/structural disease and yields non-structural/functional incomplete response in more than 80% patients, suggesting TT-DTC patients with unexplained hyperthyroglobulinemia as explicit candidates for RAT.

Cerebral β-amyloid deposits and regional glucose metabolism assessed by positron emission tomography (PET) are used to distinguish between Alzheimer's disease (AD) and other dementia syndromes. In the present multicenter study, we estimated the prevalence of β-amyloid deposits on PET imaging in a wide variety of dementia syndromes and mild cognitive impairment (MCI) within a memory clinic population. Methods: Of the 1193 consecutive patients with cognitive impairment (CI) who received combined ¹⁸F-AV45 and/or ¹¹C-PIB PET, 960 were diagnosed with AD, 36 with frontotemporal dementia (FTD), 5 with dementia with Lewy bodies (DLB), 144 with MCI, 29with vascular dementia (VaD), 4 with corticobasal syndrome (CBS) and 15 with unclassifiable dementia. Baseline clinical diagnoses were independently established without access to PET imaging results. ApoE genotype analysis was performed in CI patients and 231 gender- and age-matched controls. Results: Of the 1193 CI patients, 860 (72.1%) were amyloid-positive. The prevalence of amyloid positivity in AD and MCI patients was 86.8% (833/960) and 9.7% (14/144), respectively. In FTD patients, the prevalence of β-amyloid deposits was 5.6% (2/36). In the 4 CBS patients, two were amyloid-positive. Three of the 5 DLB patients showed amyloid positivity, as did 6 of the 29 VaD (20.7%) patients. The ApoE4 allele frequency was significantly increased in amyloid-positive CI patients (30.5%) as compared with other amyloid-negative CI patients (14%) or controls (7.3%). Conclusion: Amyloid imaging may potentially be the most helpful parameter for differential diagnosis in dementia, particularly to distinguish between AD and FTD. Amyloid PET can be used in conjunction with the ApoE4 allele genetic risk test for amyloid deposits.

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.

Research Event

Event participants

Louise Mushikiwabo, Secretary General, Organisation Internationale de la Francophonie (OIF)
Chair: Bob Dewar CMG, Associate Fellow, Africa Programme, Chatham House

31 October 2019

Trade between Central and Eastern Europe and sub-Saharan Africa has increased significantly in the last decade and a half. There is a strong case to be made for greater economic re-engagement, especially in terms of investment, that has the potential to support inclusive growth in both regions.

22 November 2019

10 December 2019

Research Event

Leukocyte recruitment is a universal feature of tissue inflammation and regulated by the interactions of chemokines with their G protein–coupled receptors. Activation of CC chemokine receptor 2 (CCR2) by its cognate chemokine ligands, including CC chemokine ligand 2 (CCL2), plays a central role in recruitment of monocytes in several inflammatory diseases. In this study, we used phosphoproteomics to conduct an unbiased characterization of the signaling network resulting from CCL2 activation of CCR2. Using data-independent acquisition MS analysis, we quantified both the proteome and phosphoproteome in FlpIn-HEK293T cells stably expressing CCR2 at six time points after activation with CCL2. Differential expression analysis identified 699 significantly regulated phosphorylation sites on 441 proteins. As expected, many of these proteins are known to participate in canonical signal transduction pathways and in the regulation of actin cytoskeleton dynamics, including numerous guanine nucleotide exchange factors and GTPase-activating proteins. Moreover, we identified regulated phosphorylation sites in numerous proteins that function in the nucleus, including several constituents of the nuclear pore complex. The results of this study provide an unprecedented level of detail of CCR2 signaling and identify potential targets for regulation of CCR2 function.

The blue mold fungus, Penicillium expansum, is a postharvest apple pathogen that contributes to food waste by rotting fruit and by producing harmful mycotoxins (e.g. patulin). To identify genes controlling pathogen virulence, a random T-DNA insertional library was created from wild-type P. expansum strain R19. One transformant, T625, had reduced virulence in apples, blistered mycelial hyphae, and a T-DNA insertion that abolished transcription of the single copy locus in which it was inserted. The gene, Blistering1, encodes a protein with a DnaJ domain, but otherwise has little homology outside the Aspergillaceae, a family of fungi known for producing antibiotics, mycotoxins, and cheese. Because protein secretion is critical for these processes and for host infection, mass spectrometry was used to monitor proteins secreted into liquid media during fungal growth. T625 failed to secrete a set of enzymes that degrade plant cell walls, along with ones that synthesize the three final biosynthetic steps of patulin. Consequently, the culture broth of T625 had significantly reduced capacity to degrade apple tissue and contained 30 times less patulin. Quantitative mass spectrometry of 3,282 mycelial proteins revealed that T625 had altered cellular networks controlling protein processing in the endoplasmic reticulum, protein export, vesicle-mediated transport, and endocytosis. T625 also had reduced proteins controlling mRNA surveillance and RNA processing. Transmission electron microscopy of hyphal cross sections confirmed that T625 formed abnormally enlarged endosomes or vacuoles. These data reveal that Blistering1 affects internal and external protein processing involving vesicle-mediated transport in a family of fungi with medical, commercial, and agricultural importance.

The increasing incidence of antimalarial drug resistance to the first-line artemisinin combination therapies underpins an urgent need for new antimalarial drugs, ideally with a novel mode of action. The recently developed 2-aminomethylphenol, JPC-3210, (MMV 892646) is an erythrocytic schizonticide with potent in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum lines, low cytotoxicity, potent in vivo efficacy against murine malaria, and favorable preclinical pharmacokinetics including a lengthy plasma elimination half-life. To investigate the impact of JPC-3210 on biochemical pathways within P. falciparum-infected red blood cells, we have applied a "multi-omics" workflow based on high resolution orbitrap mass spectrometry combined with biochemical approaches. Metabolomics, peptidomics and hemoglobin fractionation analyses revealed a perturbation in hemoglobin metabolism following JPC-3210 exposure. The metabolomics data demonstrated a specific depletion of short hemoglobin-derived peptides, peptidomics analysis revealed a depletion of longer hemoglobin-derived peptides, and the hemoglobin fractionation assay demonstrated decreases in hemoglobin, heme and hemozoin levels. To further elucidate the mechanism responsible for inhibition of hemoglobin metabolism, we used in vitro β-hematin polymerization assays and showed JPC-3210 to be an intermediate inhibitor of β-hematin polymerization, about 10-fold less potent then the quinoline antimalarials, such as chloroquine and mefloquine. Further, quantitative proteomics analysis showed that JPC-3210 treatment results in a distinct proteomic signature compared with other known antimalarials. While JPC-3210 clustered closely with mefloquine in the metabolomics and proteomics analyses, a key differentiating signature for JPC-3210 was the significant enrichment of parasite proteins involved in regulation of translation. These studies revealed that the mode of action for JPC-3210 involves inhibition of the hemoglobin digestion pathway and elevation of regulators of protein translation. Importantly, JPC-3210 demonstrated rapid parasite killing kinetics compared with other quinolones, suggesting that JPC-3210 warrants further investigation as a potentially long acting partner drug for malaria treatment.

Human antibody response studies are largely restricted to periods of high immune activity (e.g. vaccination). To comprehensively understand the healthy B cell immune repertoire and how this changes over time and through natural infection, we conducted immune repertoire RNA sequencing on flow cytometry-sorted B cell subsets to profile a single individual's antibodies over 11 months through two periods of natural viral infection. We found that 1) a baseline of healthy variable (V) gene usage in antibodies exists and is stable over time, but antibodies in memory cells consistently have a different usage profile relative to earlier B cell stages; 2) a single complementarity-determining region 3 (CDR3) is potentially generated from more than one VJ gene combination; and 3) IgG and IgA antibody transcripts are found at low levels in early human B cell development, suggesting that class switching may occur earlier than previously realized. These findings provide insight into immune repertoire stability, response to natural infections, and human B cell development.

Triple-negative breast cancer (TNBC) is characterized by poor response to therapy and low overall patient survival. Recently, Estrogen Receptor beta (ERβ) has been found to be expressed in a fraction of TNBCs where, because of its oncosuppressive actions on the genome, it represents a potential therapeutic target, provided a better understanding of its actions in these tumors becomes available. To this end, the cell lines Hs 578T, MDA-MB-468 and HCC1806, representing the claudin-low, basal-like 1 and 2 TNBC molecular subtypes respectively, were engineered to express ERβ under the control of a Tetracycline-inducible promoter and used to investigate the effects of this transcription factor on gene activity. The antiproliferative effects of ERβ in these cells were confirmed by multiple functional approaches, including transcriptome profiling and global mapping of receptor binding sites in the genome, that revealed direct negative regulation by ERβ of genes, encoding for key components of cellular pathways associated to TNBC aggressiveness representing novel therapeutic targets such as angiogenesis, invasion, metastasis and cholesterol biosynthesis. Supporting these results, interaction proteomics by immunoprecipitation coupled to nano LC-MS/MS mass spectrometry revealed ERβ association with several potential nuclear protein partners, including key components of regulatory complexes known to control chromatin remodeling, transcriptional and post-transcriptional gene regulation and RNA splicing. Among these, ERβ association with the Polycomb Repressor Complexes 1 and 2 (PRC1/2), known for their central role in gene regulation in cancer cells, was confirmed in all three TNBC subtypes investigated, suggesting its occurrence independently from the cellular context. These results demonstrate a significant impact of ERβ in TNBC genome activity mediated by its cooperation with regulatory multiprotein chromatin remodeling complexes, providing novel ground to devise new strategies for the treatment of these diseases based on ligands affecting the activity of this nuclear receptor or some of its protein partners.