Etienne Joseph Janssen

Dr. Etienne Joseph Janssen

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Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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10 December 2022 in Cancers
Verified
Journal Article
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CBCarlien Bennebroek
Carlien Bennebroek
JZJudith van Zwol
Judith van Zwol
GPGiorgio L. Porro
Giorgio L. Porro
OOOostenbrink Oostenbrink
Oostenbrink Oostenbrink
ADAnne Dittrich
Anne Dittrich
AMAntoinette Y. N. Schouten-van Meeteren
Antoinette Y. N. Schouten-van Meeteren
Backgrounds: Bevacizumab (BVZ) is used as a subsequent line of treatment for pediatric optic pathway glioma (OPG) in the case of progression. Data on the treatment effect concerning tumor progression and visual function are scarce and nationwide studies are lacking. Methods: We performed a retrospective, nationwide, multicentre cohort study including all pediatric patients with OPG treated with BVZ in the Netherlands (2009–2021). Progression-free survival, change in visual acuity and visual field, MRI-based radiologic response, and toxicity were evaluated. Results: In total, 33 pediatric patients with OPG were treated with BVZ (median 12 months). Visual acuity improved in 20.5%, remained stable in 74.4%, and decreased in 5.1% of 39 of all analysed eyes. The monocular visual field improved in 73.1%, remained stable in 15.4%, and decreased in 7.7% of 25 analysed eyes. Radiologic response at the end of therapy showed a partial response in 7 patients (21.9%), minor response in 7 (21.9%), stable disease in 15 (46.9%), and progressive disease in 3 (9.3%). Progression-free survival at 18 and 36 months after the start of BVZ reduced from 70.9% to 38.0%. Toxicity (≥grade 3 CTCAE) during treatment was observed in five patients (15.2%). Conclusion: Treatment of BVZ in pediatric patients with OPG revealed stabilisation in the majority of patients, but was followed by progression at a later time point in more than 60% of patients. This profile seems relatively acceptable given the benefits of visual field improvement in more than 70% of analysed eyes and visual acuity improvement in more than 20% of eyes at the cessation of BVZ.

1 April 2023 in Applied Sciences
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Journal Article
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ADAnne Dittrich
Anne Dittrich
EJEtienne Joseph Janssen
Etienne Joseph Janssen
JGJoyce Geelen
Joyce Geelen
KBKarlijn Bouman
Karlijn Bouman
LWLeanne M. Ward
Leanne M. Ward
JDJos M. T. Draaisma
Jos M. T. Draaisma
By definition, children constitute a vulnerable population, especially when they are chronically ill and/or disabled. A characteristic of chronically ill and disabled children is that they also suffer from indirect effects of their disease, such as immobilization, chronic inflammation, reduced time outdoors in the sun, osteotoxic effects of disease-targeted therapy (like glucocorticoids), and poor nutrition. All these factors may lead to bone fragility due to secondary osteoporosis, a co-morbidity that may be overlooked in the context of serious underlying diseases. The ultimate goal of osteoporosis diagnosis and monitoring in this setting is the early identification, prevention, and treatment of low-trauma long bone and vertebral fractures; indeed, vertebral fractures are a frequently under-diagnosed manifestation of overt bone fragility in this context. Efforts to prevent first-ever fractures are also meritorious, including encouragement of weight-bearing activities, optimization of nutritional status, including calcium and vitamin D supplementation, and the diagnosis and treatment of delayed growth and puberty; however, these conservative measures may be insufficient in those at high risk. Numerous natural history studies have shown that vertebral fractures are more common than non-vertebral (i.e., long bone) fractures in at-risk children. Not surprisingly, the cornerstone of secondary osteoporosis monitoring is lateral spine imaging for the early detection of vertebral collapse. Although dual-energy x-ray absorptiometry (DXA) is the gold standard to measure bone mineral density, digital X-ray radiogrammetry may be used as a surrogate measure of bone strength if dual-energy x-ray absorptiometry is not available. In the event that preventive measures fail, treatment with bisphosphonates may be appropriate. Typically, treatment with intravenous bisphosphonates is reserved for children with overt bone fragility and limited potential for spontaneous recovery. However, there is increasing attention to very high-risk children, such as boys with Duchenne muscular dystrophy, who may benefit from bisphosphonate therapy prior to first-ever fractures (given their high fracture frequency and essentially absent potential for spontaneous recovery). This article provides a contemporary overview of the definition and diagnosis of osteoporosis in children with chronic illness, along with the approach to monitoring those at risk and the evidence for currently recommended intervention strategies.

3 September 2020 in Clinical Dysmorphology
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Journal Article
Closed access
EJEtienne Joseph Janssen
Etienne Joseph Janssen
ASAlexander P.A. Stegmann
Alexander P.A. Stegmann
CSConstance T.R.M. Stumpel
Constance T.R.M. Stumpel
An abstract is unavailable. This article is available as a PDF only.

2 July 2025 in Science Translational Medicine
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Journal Article
Closed access
KKKohji Kato
Kohji Kato
YNYosuke Nishio
Yosuke Nishio
KMKirsty J. McMillan
Kirsty J. McMillan
AAAljazi Al-Maraghi
Aljazi Al-Maraghi
HKHester Y. Kroes
Hester Y. Kroes
PCPeter Cullen
Peter Cullen
Ritscher-Schinzel syndrome (RSS) is a congenital malformation syndrome characterized by cerebellar, cardiac, and craniofacial malformations and phenotypes associated with liver, skeletal, and kidney dysfunction. The genetic cause of RSS remains to be fully defined, and limited information is available regarding the root cause of the multiple tissue phenotypes. Causative mutations in the Commander multiprotein assembly are an emerging feature of this syndrome. Commander organizes the sorting nexin-17 (SNX17)–dependent recycling of hundreds of integral membrane proteins through the endosomal network. Here, we identify previously unrecognized cohorts of patients with RSS that we genetically and clinically analyzed to identify causative genes in the copper metabolic murr1 domain–containing (COMMD) proteins COMMD4, COMMD9, and coiled-coil domain containing 93 (CCDC93) subunits of the Commander complex. Using interactome analysis, we determined that these mutations disrupted Commander assembly and, through cell surface proteomics, that this reduces tissue-specific presentation of cell surface integral membrane proteins essential for kidney, bone, and brain development. We established that these integral proteins contained ΦxNPxY/F or ΦxNxxY/F sorting motifs in their cytoplasmic-facing domains (where Φ is a hydrophobic residue and x is any residue) that are recognized by SNX17 to drive their Commander-dependent endosomal recycling. Last, through generation of mouse models of RSS, we show replication of RSS-associated clinical phenotypes including proteinuria, skeletal malformation, and neurological impairment. Our data establish RSS as a “recyclinopathy” that arises from a dysfunction in the Commander endosomal recycling pathway.

20 February 2025 in Cancers
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Journal Article
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CBCarlien Bennebroek
Carlien Bennebroek
JZJudith van Zwol
Judith van Zwol
MSMaartje C. Montauban van Swijndregt
Maartje C. Montauban van Swijndregt
GPGiorgio L. Porro
Giorgio L. Porro
OOOostenbrink Oostenbrink
Oostenbrink Oostenbrink
AMAntoinette Y. N. Schouten-van Meeteren
Antoinette Y. N. Schouten-van Meeteren
Background: The current standard therapy for pediatric optic pathway/hypothalamic glioma (OPHG) is systemic anticancer therapy (SAT) over surgery and radiotherapy. Nevertheless, recurrent radiological or clinical tumor progression after SAT forms a considerable challenge. Sporadic OPHGs are considered to have a higher tendency toward progression after first-line systemic anticancer therapy (SAT) compared to neurofibromatosis type-1-associated (NF1) OPHGs. Methods: The objective of this study was to conduct a national retrospective cohort analysis of children who received various treatments for a progressive OPHG, involving the hypothalamus and/or chiasm and/or optic radiations. The study aimed to examine the differences in clinical course and the range of treatment modalities applied to both sporadic and NF1-associated OPHGs between 1995 and 2020. Additionally, we sought to identify risk factors for 3- and 5-year progression following first- and second-order SAT. Results: In total, 136 children received treatment, of whom 49 of 136 (36.0%) had NF1. Within a median of 7.5 years (range: 0.1–23.8 years) of follow-up, sporadic OPHGs received more treatments compared to NF1-associated OPHGs (median of 2 (range: 1–8) vs. median of 1 (range: 1–7) (p < 0.01)). Nine children with sporadic OPHGs (6.6%) died. Of 112 children (82.4%) receiving SAT, 92% received combined first-line vincristine and carboplatin. These children had a 3- and 5-year progression-free survival of 61.8% (95% CI: 51.0–72.6%) and 48.4% (95% CI: 38.0–58.8%), respectively. Sporadic OPHGs had a higher rate of second progression (p < 0.01). Starting first-line vincristine and carboplatin at an age below one year was the only independent risk factor for progression. Conclusions: In this national historic cohort of pediatric OPHGs, four out of five children received SAT. Sporadic OPHGs received a higher number of various SATs compared to NF1-associated OPHGs, but the sporadic appearance of OPHGs was not an independent risk factor for progression after combined vincristine and carboplatin, as ‘age below one year at the start’ was the only factor.

3 August 2021 in Neurology
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EJEtienne Joseph Janssen
Etienne Joseph Janssen
MOMayke Oosterloo
Mayke Oosterloo
EREstela Rubio-Gozalbo
Estela Rubio-Gozalbo
KGKoen van Gassen
Koen van Gassen
JNJoost Nicolai
Joost Nicolai