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In recent decades, medical research has been primarily focused on the inherited aspect of cancers, despite the reality that only 5-10% of tumours discovered are derived from genetic causes. Cancer is a broad term, and therefore it is inaccurate to address it as a purely genetic disease. Understanding cancer cells' behaviour is the first step in countering them. Behind the scenes, there is a complicated network of environmental factors, DNA errors, metabolic shifts, and electrostatic alterations that build over time and lead to the illness's development. This latter aspect has been analyzed in previous studies, but how the different electrical changes integrate and affect each other is rarely examined. Every cell in the human body possesses electrical properties that are essential for proper behaviour both within and outside of the cell itself. It is not yet clear whether these changes correlate with cell mutation in cancer cells, or only with their subsequent development. Either way, these aspects merit further investigation, especially with regards to their causes and consequences. Trying to block changes at various levels of occurrence or assisting in their prevention could be the key to stopping cells from becoming cancerous. Therefore, a comprehensive understanding of the current knowledge regarding the electrical landscape of cells is much needed. We review four essential electrical characteristics of cells, providing a deep understanding of the electrostatic changes in cancer cells compared to their normal counterparts. In particular, we provide an overview of intracellular and extracellular pH modifications, differences in ionic concentrations in the cytoplasm, transmembrane potential variations, and changes within mitochondria. New therapies targeting or exploiting the electrical properties of cells are developed and tested every year, such as pH-dependent carriers and tumour-treating fields. A brief section regarding the state-of-the-art of these therapies can be found at the end of this review. Finally, we highlight how these alterations integrate and potentially yield indications of cells' malignancy or metastatic index.

This study provides a first direct comparison between positron emission tomography (PET) radioligands targeting the allosteric site of the metabotropic glutamate receptor 5 (mGluR5): [11C]ABP688 and [18F]FPEB. A blocking paradigm was set up to substantiate the common binding site of both radioligands. Second, both radioligands were applied in Sapap3 knockouts showing compulsive-like behavior characterized by a lower in vivo mGluR5 availability. METHODS First, wildtype mice (n=7) received four μPET/CT scans: an [11C]ABP688 and [18F]FPEB scan, and two blocking scans using cold FPEB and cold ABP688, respectively. A second experiment compared both radioligands in wildtype (n=7) and Sapap3 knockout mice (n=10). The simplified reference tissue method was used to calculate the nondisplaceable binding potential (BPND) representing the in vivo availability of the mGluR5 in the brain. RESULTS Using cold FPEB as a blocking compound for [11C]ABP688 μPET and vice versa, we observed averaged global reductions in mGluR5 availability of circa 98% for [11C]ABP688 and 82%-96% for [18F]FPEB. For knockouts, the [11C]ABP688 BPND was on average 25% lower compared to wildtype controls (p

Background: Data from recently published trials have provided practice-changing recommendations for the surgical approach to the axilla in breast cancer. Patients with T1-2 lesions, treated with breast conservation, who have not received neoadjuvant chemotherapy and have 1-2 positive sentinel nodes (Z0011-criteria) may avoid axillary lymph node dissection (ALND). We aim to describe the dissemination of this practice in Europe over an extended period of time. Methods: Our source of data was the eusomaDB, a central data warehouse of prospectively collected information of the European Society of Breast Cancer Specialists (EUSOMA). We identified cases fulfilling Z0011-criteria from 2005 to 2016 from 34 European breast centers and report trends in ALND. Data derived from Germany, Italy, Belgium, Switzerland, Austria, and Netherlands. Results: 6671 patients fulfilled Z0011-criteria. Rates of ALND showed a statistically significant decrease from 2010 (89%) to 2011 (73%), reaching 46% in 2016 (p < 0.001). After multivariable analysis, factors associated with higher probability of ALND were earlier year of surgery, younger age, increasing tumor size and grade, and being operated in Italy (p < 0.001). The minimum and maximal rates of ALND in the most recent two-year period (2015-2016) were 0% and 83% in two centers located in different countries (p < 0.001). Conclusion: Our study demonstrates, a decrease in rates of ALND that started after year 2010 through the end of the study period. Wide differences were observed among centers and countries indicating the need to spread unified clinical guidelines in Europe to allow for homogeneous evidence-based practice patterns. (C) 2019 Elsevier Ltd. All rights reserved.

Introduction: Biorthogonal pretargeted imaging using the inverse electron demand Diels Alder (IEDDA) reaction between tetrazine (Tz) and trans-cyclooctene (TCO) is one of the most attractive strategies in molecular imaging. It allows the use of short-lived radioisotopes such as fluorine-18 for imaging of long circulating vectors with improved imaging contrast and reduced radiation dose. Here we aim to develop a novel F-18-labeled transcyclooctene (TCO) with improved metabolic stability and assess its potential usefulness in a pretargeted PET imaging approach. Methods: We have synthetized a new TCO-analogue containing a 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) chelator, allowing radiolabeling by chelation with aluminum fluoride (Al[F-18]F). Stability and pharmacokinetic profile of Al[(HF)-H-18-NOTA-TCO ([F-18]MICA-205) were evaluated in healthy animals at different timepoints after injection of the radiotracer. To assess the potential use of this new PET tracer for tumor targeting, in vivo pretargeted PET imaging was performed in LS174T tumor-bearing mice pre-treated with a tetrazine-modified anti-TAG-72 monoclonal antibody (CC49). Results: The radiotracer was obtained with a radiochemical yield (RCY) of 12.8 +/- 2.8% and a radiochemical purity (RCP) of >= 95%. It also showed a promising in vivo stability with 51.9 +/- 5.16% of radiotracer remaining intact after 1 h. The biodistribution in healthy mice demonstrated mixed hepatobiliary and renal clearance, with a rapid blood clearance and low uptake in other tissues. The low bone uptake indicated lack of tracer defluorination. Interestingly, a pretargeted PET imaging experiment showed a significantly increased radiotracer uptake (0.67 +/- 0.16%ID/g, p < 0.001) in the tumors of mice pre-treated with CC49-tetrazine compared to the CC49 alone (0.16 0.08%ID/g). Conclusions: [189 MICA-205 represents a large improvement in in vivo metabolic stability compared to previous reported F-18-labeled TCOs, allowing a clear visualization of tumor tissue in a small-animal pretargeted PET imaging experiment. Despite the favorable in vivo stability and image contrast obtained with [F-18]MICA-205, the development of next-generation derivatives with increased absolute tumor uptake is warranted for future pretargeting applications. (C) 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Particulate matter (PM) is a complex, heterogeneous mixture that changes in time and space. It has many different chemical constituents, several of which have been identified as potential contributors to toxicity, and varying physical characteristics. Identifying and quantifying the effects of specific components or source-related combinations on human health, particularly when particles interact with other co-pollutants, therefore represents one of the most challenging areas of environmental health research. Owing to the importance of PM10 chemical composition in understanding particulate pollution sources, 1942 PM10 samples were simultaneously collected at five sites (four urban background sites located in Amsterdam (AD), Antwerp (AP), Leicester (LE) and Lille (LL), and one industrial site at Wijk aan Zee (WZ)) across North-West Europe from April 2013 to May 2014, and chemical species and sources of PM10 were investigated. PM10 samples were chemically analysed for water-soluble ions (NO3−, SO42−, Cl−, NH4+, Na+, K+, Mg2+, and Ca2+), carbonaceous species (OC, and EC), minerals (Al, Ca, Fe, Ti, and K), trace elements (As, Ba, Cd, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, and Zn), and monosaccharides (levoglucosan, galactosan, and mannosan). Spatial and seasonal variations of the atmospheric concentrations of species were also investigated. In order to reconstruct the particle mass, the determined constituents were classified into seven classes as follows: mineral dust (MD), organic matter (OM), elemental carbon (EC), trace elements (TE), sea salt (SS), secondary inorganic aerosol (SIA), and monosaccharides (MSS). Strong correlations (R2 = 0.88–0.96) were found between chemically determined and gravimetrically measured PM10 masses for all sites. According to chemical mass closure, the major components of PM10 were SIA, followed by OM and MD at the four urban sites, and the major components of PM10 were SIA, followed by MD and SS at an industrially influenced site. SIA dominated the PM10 profiles at all sites, accounting for 36, 35, 32, 36, and 32% at AD, AP, LE, LL, and WZ, respectively. Five PCA factors explained 67, 80, 76, and 74% of the variance of the data at AD, AP, LL and WZ respectively. In addition, four factors are extracted for LE site explaining 71% of the variance. The PCA results showed that secondary aerosols, biomass burning, and traffic emissions were the most important sources across North-West Europe.

Background Successfully treated HIV-1 infected patients have a sustained undetectable viral RNA load. In these cases the total HIV-1 DNA load may constitute a valuable tool to further follow the overall viral burden. The value of this marker outside of cure research has been rarely studied. Objectives To develop a quantitative (q)PCR for total HIV-1 DNA quantification in buffy coat cells and to evaluate the value of this parameter in clinical follow-up. Study design A qPCR using primers and a probe in the conserved HIV-1 LTR region was adapted for use on DNA extracted from buffy coat cells. Sensitivity, accuracy and reproducibility were evaluated using 8E5 cells and samples from naive and treatment experienced patients. The clinical value of DNA load analysis was assessed by testing 119 longitudinal samples from 9 patients before and after ART initiation and 249 cross sectional samples from therapy-experienced patients. Results Inter- and intra-assay coefficients of variability were 5.56 and 5.94 (%CV). HIV-1 DNA was detected in 249 of the 263 (94.7%) patients on ART for at least 5 months (median: 53 months; IQR: 28–84 months). The HIV-1 DNA load varied between 0.60 and 3.37 copies/106 blood cells and showed significant correlation with the pre-ART CD4+ T-cell count nadir and peak viral RNA load. ART initiation resulted in a slow and limited decline of the total HIV-1 DNA concentration. Conclusions Quantification of total HIV-1 DNA from buffy coat cells is feasible, sensitive and reliable. Although determination of the on-therapy HIV-1 DNA load may be informative, regular testing has limited clinical value because of the very slow evolution.

Introduction Du fait de la nature chronique du psoriasis en plaques, il est important de maintenir l’efficacite du traitement dans le temps. Nous rapportons ici les resultats groupes de trois etudes de phase 3 concernant le maintien de la reponse sur 1 an chez des patients presentant un psoriasis en plaques modere a severe et qui ont obtenu un blanchiment complet ou quasi complet des lesions apres 16 semaines de traitement par bimekizumab. Materiel et methodes Nous avons groupe les donnees des etudes de phase 3 BE VIVID, BE READY et BE SURE. Les patients inclus ont ete randomises pour recevoir du bimekizumab a raison de 320 mg toutes les 4 semaines (Q4S) jusqu’a la semaine 16, puis ils ont continue a recevoir du bimekizumab Q4S (Q4S/Q4S) ou ils sont passes a du bimekizumab a raison de 320 mg toutes les 8 semaines (Q4S/Q8S). Nous rapportons les resultats des reponses PASI90, IGA0/1 et PASI100 a la semaine 52 chez les patients repondeurs a la semaine 16. Les donnees manquantes ont ete imputees comme une absence de reponse. Resultats Sur les 989 patients randomises pour recevoir du bimekizumab a raison de 320 mg Q4S dans ces etudes, la plupart ont obtenu un blanchiment complet ou quasi complet des lesions a la semaine 16 (PASI90 : 87,5 % ; IGA0/1 : 87,5 % ; PASI100 : 62,7 %). Parmi les repondeurs PASI90 a la semaine 16 dans les groupes Q4S/Q4S (n = 516) et Q4S/Q8S (n = 237), 89,9 % et 90,3 % ont respectivement maintenu la reponse PASI90 a la semaine 52. Parmi les repondeurs IGA0/1 a la semaine 16 dans les groupes de traitement Q4S/Q4S (n = 511) et Q4S/Q8S (n = 234), 87,5 % et 91,5 % ont maintenu la reponse IGA0/1 a la semaine 52. Parmi les repondeurs PASI100 a la semaine 16 dans les groupes Q4S/Q4S (n = 355) et Q4S/Q8S (n = 182), 83,1 % et 88,5 % ont maintenu la reponse PASI100 a la semaine 52. Discussion Une proportion importante de patients qui avaient obtenu un blanchiment complet ou quasi complet des lesions apres 16 semaines de traitement par bimekizumab ont maintenu leurs reponses jusqu’a la semaine 52, quel que soit le schema d’administration utilise pendant la periode d’entretien (Q4S ou Q8S).

This paper gives the description of a new direct chemical plating method for silver, called the Jet Metal (JMT) process and of the Jet Selective process, which allows obtaining a selective metallization on any substrate which can be metallized with the Jet Metal process (Stremsdoerfer, n.d. [1]). This technology is based on spraying separately an aqueous solution containing silver metallic ions together with a CMR free, aqueous based reducing agent. This process allows plating chemical silver at 12 μm/h at room temperature and at ambient pressure and is already used in industrial processes for metallizing plastics, composites and non-conductive materials in general and this in different formats (3D pieces, 2D foils, …). In the second part, some functional applications are discussed.

Background: Molecular neuroimaging was applied in the quinpirole rat model for compulsive checking in OCD to visualize the D2- and mGluR5-receptor occupancy with Raclopride and ABP-688 microPET/CT. Methods: Animals (n = 48) were exposed to either saline (CTRL; 1 mL/kg) or quinpirole (QP; dopamine D2-agonist, 0.5 mg/kg) in a single injection (RAC and ABP acute groups) or twice-weekly during 7 weeks (chronic group). Animals underwent PET/CT after the 1st injection (acute) or before initial exposure and following the 10th injection in week 5 (chronic). For the latter, each injection was paired with an open field test and video tracking. Results: The QP animals displayed a strong increase in visiting frequency (checking) in the chronic group (+ 699.29%) compared to the control animals. Acute administration of the drug caused significant (p < 0.01) decreases in D2R occupancy in the CP (- 42.03% +/- 4.01%). Chronical exposure resulted in significantly stronger decreases in the CP (- 52.29% +/- 3.79%). Furthermore significant increases in mGluR5 occupancy were found in the CP (10.36% +/- 4.09%), anterior cingulate cortex (13.26% +/- 4.01%), amygdala (24.36% +/- 6.86%), entorhinal cortex (18.49% +/- 5.14%) and nucleus accumbens (13.8% +/- 4.87%) of the chronic group, not present after acute exposure. Conclusions: Compared to acute exposure, sensitisation to QP as a model for OCD differs both on a dopaminergic and glutamateric level, indicating involvement of processes such as receptor internalization and changes in extracellular availability of both neurotransmitters.

Background Gloriosa superba L. (glory lily, Colchicaceae) contains colchicine, and related alkaloids such as 3- O -demethylcolchicine and its glycoside colchicoside. Previously the in vivo efficacy of a crude extract and a colchicine-poor / colchicoside-rich extract of G. superba seeds was shown in a murine model of pancreatic adenocarcinoma. Hypothesis/Purpose The efficacy can be improved without obvious signs of toxicity by increasing the treatment dose; the efficacy of gemcitabine can be improved by coadministration of a Gloriosa superba extract. Study design A survival experiment was carried out in a murine model of pancreatic adenocarcinoma and the semi-long-term toxicity of both G. superba extracts was determined; a combination therapy with gemcitabine was evaluated. Methods A crude ethanolic extract (GS) and a colchicine-poor / colchicoside-rich extract (GS2B) were prepared, containing 3.22% colchicine, 2.52% colchicoside and 1.52% 3- O -demethylcolchicine (GS), and 0.07%, 2.26% and 0.46% (m/m) (GS2B). They were evaluated in a murine model of pancreatic adenocarcinoma at a dose of 4.5 mg/kg (p.o., daily) total content of colchicine and derivatives during 3 weeks, or at 3.0 mg/kg (p.o., daily) combined with gemcitabine (60 mg/kg, i.p., 3x/week) during 54 days. Results A significant effect in tumour growth over time was observed for gemcitabine and the combination therapy compared to the control group. No significant difference was observed for the groups treated with colchicine and both extracts. However, combination therapy was significantly better than the monotherapy with gemcitabine. Moreover, survival analysis showed a significant prolongation of the survival of the groups treated with gemcitabine and the combination therapy. A slight difference in survival was observed between gemcitabine and the combination therapy, the latter one being slightly better. No significant prolongation of survival was observed for the extracts and colchicine compared to the control group. Conclusion Although a relevant tumour growth inhibition and a difference of relative tumour volume compared to the control group were observed on day 11, and a slightly longer survival was noticed for GS2B, the most important conclusion from this study is that the crude G. superba extract (GS) might have an added value combined with gemcitabine in the treatment of pancreatic tumours.

BACKGROUND: Endocrine disrupting chemicals represent a broad class of compounds, are widespread in the environment and can pose severe health effects. OBJECTIVES: The objective of this study was to investigate and compare the overall estrogen and androgen activating potential of PM(10) air samples at an urban, rural and industrial location in Flanders, using a human in vitro cell bioassay. METHODS: PM(10) samples were collected on glass fiber filters every six days between April 2013 and January 2014 using a high-volume sampler. Extraction was executed with a hexane/acetone mixture before analysis using a recombinant estrogen- or androgen responsive human carcinoma cell line. Results were expressed as bioanalytical equivalents (BEQs) per cubic meter of air. RESULTS: High fluctuations in estrogenic activity were observed during the entire sampling period, with median BEQs of 32.1, 35.9 and 31.1 fg E2-Eq m(−3) in the industrial, urban and rural background area, respectively. Estrogenic activity was measured in 70% of the samples, while no androgenic activity was observed in any of the samples. The estrogenic activity in the industrial area was positively correlated with the airborne concentration of the sum of the non-carcinogenic PAHs pyrene and fluoranthene (rho = 0.48; p < 0.01) and the sum of the carcinogenic PAHs (rho = 0.36 p = 0.05). CONCLUSIONS: This study showed that no androgenic activity was present in PM(10) and that although the median estrogenic activity was rather low and comparable in the three locations, high fluctuations in estrogenic response exist over time. While atmospheric PAHs contributed to the observed estrogenic response, especially in the industrial area, the chemicals responsible for the majority of estrogenic activity remain to be identified.

Atmospheric particulate pollution is a significant problem across the EU and there is concern that there may be an increasing contribution from biomass burning, driven by rising fuel prices and an increased interest in the use of renewable energy sources. This study was carried out to assess current levels of biomass burning and the contribution to total PM10 across five sites in North-West Europe; an area which is frequently affected by poor air quality. Biomass burning was quantified by the determination of levoglucosan concentrations from PM10 aerosol filters collected over a 14 month period in 2013/2014 and continued for a further 12 months at the UK site in Leicester. Levoglucosan levels indicated a distinct period of increased biomass combustion between November and March. Within this period monthly average concentrations ranged between 23 +/- 9.7 and 283 +/- 163 ng/m(3), with Lille showing consistently higher levels than the sites in Belgium, the Netherlands and the UK. The estimated contribution to PM10 was, as expected, highest in the winter season where the season average percentage contribution was lowest in Wijk aan Zee at 2.7 +/- 1.4% and again highest in Lille at 11.6 +/- 3.8%, with a PM10 mass concentration from biomass that ranged from 0.56 mu g/m(3) in Leicester to 2.08 mu g/m(3) in Lille. Overall there was poor correlation between the levoglucosan concentrations measured at the different sites indicating that normally biomass burning would only affect atmospheric particulate pollution in the local area; however, there was evidence that extreme burning events such as the Easter fires traditionally held in parts of North-West Europe can have far wider ranging effects on air quality. Network validation measurements were also taken using a mobile monitoring station which visited the fixed sites to carry out concurrent collections of aerosol filters; the result of which demonstrated the reliability of both PM10 and levoglucosan measurements. (C) 2016 Elsevier Ltd. All rights reserved.

Objectives: Body fluid composition changes during the course of pregnancy and there is evidence to suggest that these changes are different in uncomplicated pregnancies compared to hypertensive pregnancies. The aim of this study was to evaluate the changes in maternal body fluid composition during the course of an uncomplicated pregnancy and to assess differences in uncomplicated pregnancies versus hypertensive pregnancies by using a bio-impedance analysis technique. Study design: Body fluid composition of each patient was assessed using a multiple frequency bioelectrical impedance analyser. Measurements were performed in 276 uncomplicated pregnancies, 34 patients with gestational hypertension, 35 with late onset preeclampsia and 11 with early onset preeclampsia. Statistical analysis was performed at nominal level alpha = 0.05. A longitudinal linear mixed model based analysis was performed for longitudinal evolutions, and ANOVA with a post-hoc Bonferroni was used to identify differences between groups. Results: Measurements showed that total body water (TBW), intracellular (ICW) and extracellular water (ECW) and ECW/ICW significantly increase during the course of pregnancy. Late onset preeclampsia is associated with a higher TBW and ECW as compared to uncomplicated pregnancies, the ECW/ICW ratio is higher in preeclamptic patients compared to uncomplicated pregnancies and gestational hypertension, and ICW is not different between groups. Conclusion: Body fluid composition changes differently during the course of uncomplicated pregnancies versus hypertensive pregnancies. This work is part of a PhD-thesis, which is supported by the Limburg Clinical Research Program (LCRP) UHasselt-ZOL-Jessa, supported by the foundation Limburg Sterk Merk, Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital.

Particulate black carbon has a range of negative impacts on health, the environment and climate, however despite this there are relatively few long-term studies on its ambient distribution as a tropospheric air pollutant. In order to address this lack of data, to help to provide greater insight into the spatio-temporal distribution of particulate black carbon and to assess potential influencing factors, a new, permanent suburban monitoring network was established with sites in four northwest European cities: London (UK), Leicester (UK), Amsterdam (the Netherlands) and Antwerp (Belgium). We report here an analysis of the first measurements made by the network over a twenty-seven-month period (January 01, 2013–April 01, 2015), alongside data from pre-existing comparator urban roadside (AURN Marylebone Road, London, UK) and rural background (AURN Auchencorth Moss, Scotland) sites. The temporal evolution of black carbon was investigated at each site, as were associations with other commonly monitored pollutants (e.g. O3, NOx, PM2.5, PM10) and wind fields. Results showed clear anthropogenic signatures across the diurnal, weekly and annual timeframes, and positive correlations were obtained between black carbon measurements and other common traffic-related pollutants, highlighting the importance of vehicle emissions as a major contributor to ambient black carbon concentration in northwest Europe. Average black carbon concentrations varied from 6.6 μg m−3 at the urban roadside, to 0.2 μg m−3 in the rural background, with suburban and urban background sites having average concentrations in the range of 1.0–2.4 μg m−3. Wind field analysis further highlighted the importance of road traffic as a source of black carbon and demonstrated the importance of local emission sources at the various receptor locations. Statistical analysis of data between sites generally indicated a weak correlation (rs = −0.03 to 0.68, COD = 0.32–0.91), further highlighting the importance of local emissions in determining ambient black carbon concentration. It was also found that black carbon comprised a significant portion of total ambient particulate matter (PM), particularly at sites with the larger traffic volumes and during rush-hour (e.g. ~45% of PM2.5 at Marylebone Road), however, its contribution to total PM was found to decrease on days of high pollution, indicating the importance of other PM components when air quality is particularly poor.

UNLABELLED: We aimed to evaluate [3-(6-methyl-pyridin-2-ylethynyl)-cyclohex-2-enone-0-11C-methyloxime] ([11C]ABP688) small animal positron emission tomography (μPET) as a biomarker to visualize possible longitudinal changes in metabotropic glutamate receptor 5 (mGluR5) availability in the brain of SAP90/PSD-95 associated protein 3 (Sapap3) knockout (ko) mice, showing obsessive compulsive disorder (OCD)-like behavior. METHODS: Alongside the assessment of grooming, we performed [11C]ABP688 μPET/CT imaging in wildtype (wt; n=10) and ko (n=11) mice both at 3 and 9 months. Using the simplified reference tissue method (SRTM), the nondisplaceable binding potential (BPND) was calculated representing the in vivo availability of the metabotropic glutamate receptor 5 (mGluR5) in the brain with the cerebellum as a reference region. Longitudinal voxel-based statistical parametric mapping (SPM) was performed on BPND images. Results were verified using [11C]ABP688 ex vivo autoradiography, [3H]ABP688 in vitro autoradiography, and mGluR5 immunohistochemistry. RESULTS: Cross-sectional comparisons revealed significantly increased grooming parameters in ko animals, at both time points. A significant longitudinal increase in % grooming duration (+268.25%; p

Highlights • Hydroxychloroquine (HCQ) 2400 mg over 5 days was used in Belgium for COVID-19. • Impact of HCQ on mortality among 8075 patients with COVID-19 was assessed. • Lower mortality in HCQ-treated patients as compared to supportive care. • Lower mortality was irrespective of symptom duration., Hydroxychloroquine (HCQ) has been largely used and investigated as therapy for COVID-19 across various settings at a total dose usually ranging from 2400 mg to 9600 mg. In Belgium, off-label use of low-dose HCQ (total 2400 mg over 5 days) was recommended for hospitalised patients with COVID-19. We conducted a retrospective analysis of in-hospital mortality in the Belgian national COVID-19 hospital surveillance data. Patients treated either with HCQ monotherapy and supportive care (HCQ group) were compared with patients treated with supportive care only (no-HCQ group) using a competing risks proportional hazards regression with discharge alive as competing risk, adjusted for demographic and clinical features with robust standard errors. Of 8075 patients with complete discharge data on 24 May 2020 and diagnosed before 1 May 2020, 4542 received HCQ in monotherapy and 3533 were in the no-HCQ group. Death was reported in 804/4542 (17.7%) and 957/3533 (27.1%), respectively. In the multivariable analysis, mortality was lower in the HCQ group compared with the no-HCQ group [adjusted hazard ratio (aHR) = 0.684, 95% confidence interval (CI) 0.617–0.758]. Compared with the no-HCQ group, mortality in the HCQ group was reduced both in patients diagnosed ≤5 days (n = 3975) and >5 days (n = 3487) after symptom onset [aHR = 0.701 (95% CI 0.617–0.796) and aHR = 0.647 (95% CI 0.525–0.797), respectively]. Compared with supportive care only, low-dose HCQ monotherapy was independently associated with lower mortality in hospitalised patients with COVID-19 diagnosed and treated early or later after symptom onset.