Publications by authors named "Gert-Jan Meersma"

Objective: Meningiomas are one of the most frequently occurring brain tumors and can be curatively treated with gross-total resection. A subtotal resection increases the chances of recurrence. The intraoperative identification of invisible tumor remnants by using a fluorescent tracer targeting an upregulated biomarker could help to optimize meningioma resection.

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Background: The poor chemo-response and high DNA methylation of ovarian clear cell carcinoma (OCCC) have attracted extensive attentions. Recently, we revealed the mutational landscape of the human kinome and additional cancer-related genes and found deleterious mutations in ARID1A, a component of the SWI/SNF chromatin-remodeling complex, in 46% of OCCC patients. The present study aims to comprehensively investigate whether ARID1A loss and genome-wide DNA methylation are co-regulated in OCCC and identify putative therapeutic targets epigenetically regulated by ARID1A.

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Purpose: The ability to identify residual tumor tissues in patients with locally advanced esophageal cancer following neoadjuvant chemoradiotherapy (nCRT) is essential for monitoring the treatment response. Using the fluorescent tracer bevacizumab-800CW, we evaluated whether ultrasound-guided quantitative fluorescent molecular endoscopy (US-qFME), which combines quantitative fluorescence molecular endoscopy (qFME) with ultrasound-guided needle biopsy/single-fiber fluorescence (USNB/SFF), can be used to identify residual tumor tissues in patients following nCRT.

Experimental Design: Twenty patients received an additional endoscopy procedure the day before surgery.

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Objective: Meningiomas are frequently occurring, often benign intracranial tumors. Molecular fluorescence can be used to intraoperatively identify residual meningioma tissue and optimize safe resection; however, currently no clinically approved agent is available for this specific tumor type. In meningiomas, vascular endothelial growth factor α (VEGFα) is upregulated, and this biomarker could be targeted with bevacizumab-IRDye800CW, a fluorescent agent that is already clinically applied for the resection of other tumors and neoplasms.

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Barrett’s esophagus (BE) is the precursor of esophageal adenocarcinoma (EAC). Dysplastic BE (DBE) has a higher progression risk to EAC compared to non-dysplastic BE (NDBE). However, the miss rates for the endoscopic detection of DBE remain high.

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Vulnerable atherosclerotic carotid plaques are prone to rupture, resulting in ischemic strokes. In contrast to radiological imaging techniques, molecular imaging techniques have the potential to assess plaque vulnerability by visualizing diseases-specific biomarkers. A risk factor for rupture is intra-plaque neovascularization, which is characterized by overexpression of vascular endothelial growth factor-A (VEGF-A).

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Testicular cancer (TC) is the most common solid tumour in young men. While cisplatin-based chemotherapy is highly effective in TC patients, chemoresistance still accounts for 10% of disease-related deaths. Pre-clinical models that faithfully reflect patient tumours are needed to assist in target discovery and drug development.

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Article Synopsis
  • Fluorescence molecular endoscopy (FME) is being explored as a promising technique to enhance diagnosis and treatment in gastroenterology, particularly in Barrett's Esophagus (BE) patients.
  • In a study involving 15 patients, different doses and methods of administering a fluorescent tracer (EMI-137) targeting c-Met were tested to assess its safety and effectiveness in identifying lesions.
  • While FME using EMI-137 showed promising results, with 16 out of 18 lesions correctly identified, the study suggests that it may not be the best option for improving BE surveillance, but it does provide crucial parameters for future clinical studies on FME techniques.
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Tumor-positive resection margins are present in up to 23% of head and neck cancer (HNC) surgeries, as intraoperative techniques for evaluation of the resection margins are lacking. In this study, we investigated the safety and potential clinical value of fluorescence-guided imaging (FGI) for resection margin evaluation in HNC patients. We determined the optimal cetuximab-800CW dose by quantification of intrinsic fluorescence values using multi-diameter single-fiber reflectance, single-fiber fluorescence (MDSFR/SFF) spectroscopy.

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Testicular cancer is the most common cancer type among young men. Despite highly effective cisplatin-based chemotherapy, around 20% of patients with metastatic disease will still die from the disease. The aim of this study was to explore the use of kinase inhibitors to sensitize testicular cancer cells to cisplatin treatment.

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Current treatment for advanced stage ovarian clear cell cancer is severely hampered by a lack of effective systemic therapy options, leading to a poor outlook for these patients. Sequencing studies revealed that ARID1A is mutated in over 50% of ovarian clear cell carcinomas. To search for a rational approach to target ovarian clear cell cancers with ARID1A mutations, we performed kinome-centered lethality screens in a large panel of ovarian clear cell carcinoma cell lines.

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Background: Despite an early response to platinum-based chemotherapy in advanced stage high-grade serous ovarian cancer (HGSOC), the majority of patients will relapse with drug-resistant disease. Aberrant epigenetic alterations like DNA methylation are common in HGSOC. Differences in DNA methylation are associated with chemoresponse in these patients.

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Background: In high-grade serous ovarian cancer (HGSOC), intrinsic and/or acquired resistance against platinum-containing chemotherapy is a major obstacle for successful treatment. A low frequency of somatic mutations but frequent epigenetic alterations, including DNA methylation in HGSOC tumors, presents the cancer epigenome as a relevant target for innovative therapy. Patient-derived xenografts (PDXs) supposedly are good preclinical models for identifying novel drug targets.

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Using patient-derived xenografts (PDXs) for preclinical cancer research demands proper storage of tumour material to facilitate logistics and to reduce the number of animals needed. We successfully established 45 subcutaneous ovarian cancer PDXs, reflecting all histological subtypes, with an overall take rate of 68%. Corresponding cells from mouse replaced human tumour stromal and endothelial cells in second generation PDXs as demonstrated with mouse-specific vimentin and CD31 immunohistochemical staining.

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New treatment targets need to be identified in gastrointestinal stromal tumors (GISTs) to extend the treatment options for patients experiencing failure with small-molecule tyrosine kinase inhibitors, such as imatinib. Insulin-like growth factor (IGF)-II acts as an autocrine factor in several tumor types by binding to IGF receptor type 1 (IGF-1R) and/or the insulin receptor (IR) isoform A. The aim of the present study was to investigate the putative role of unprocessed pro-IGF-II, called 'big'-IGF-II, in GISTs.

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Purpose: Recombinant human tumor necrosis factor-related apoptosis-inducing ligand (rhTRAIL) is clinically evaluated as novel anticancer drug. rhTRAIL-DR5, a rhTRAIL variant that specifically binds to DR5 receptor, has recently been developed. We investigated whether rhTRAIL-DR5 is more efficient than rhTRAIL in combination with cisplatin in DR5-expressing human A2780 ovarian cancer cells.

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Background: Ovarian cancer has a poor prognosis due to advanced stage at presentation and either intrinsic or acquired resistance to classic cytotoxic drugs such as platinum and taxoids. Recent large clinical trials with different combinations and sequences of classic cytotoxic drugs indicate that further significant improvement in prognosis by this type of drugs is not to be expected. Currently a large number of drugs, targeting dysregulated molecular pathways in cancer cells have been developed and are introduced in the clinic.

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Purpose: To investigate the potential of irradiation in combination with drugs targeting the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor (DR)4 and DR5 and their mechanism of action in a cervical cancer cell line.

Methods And Materials: Recombinant human TRAIL (rhTRAIL) and the agonistic antibodies against DR4 and DR5 were added to irradiated HeLa cells. The effect was evaluated with apoptosis and cytotoxicity assays and at the protein level.

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Background: Factor analysis (FA) has been widely applied in microarray studies as a data-reduction-tool without any a-priori assumption regarding associations between observed data and latent structure (Exploratory Factor Analysis).A disadvantage is that the representation of data in a reduced set of dimensions can be difficult to interpret, as biological contrasts do not necessarily coincide with single dimensions. However, FA can also be applied as an instrument to confirm what is expected on the basis of pre-established hypotheses (Confirmatory Factor Analysis, CFA).

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