Publications

We report the derivation of 30 patient-derived organoid lines (PDOs) from tumors arising in the pancreas and distal bile duct. PDOs recapitulate tumor histology and contain genetic alterations typical of pancreatic cancer. In vitro testing of a panel of 76 therapeutic agents revealed sensitivities currently not exploited in the clinic, and underscores the importance of personalized approaches for effective cancer treatment. The PRMT5 inhibitor EZP015556, shown to target MTAP (a gene commonly lost in pancreatic cancer)-negative tumors, was validated as such, but also appeared to constitute an effective therapy for a subset of MTAP-positive tumors. Taken together, the work presented here provides a platform to identify novel therapeutics to target pancreatic tumor cells using PDOs.

<p>Targeted gene sequencing of patient derived organoids</p>

<title>Abstract</title> 5-fluorouracil (5-FU) is the backbone for chemotherapy in colorectal cancer (CRC), however response rates in patients are limited to 50%. Unexpectedly, the molecular mechanisms by which 5-FU ultimately induces toxicity remain debated, limiting the development of strategies to improve its efficacy. How fundamental aspects of cancer, such as driver mutations and phenotypic intra-tumor heterogeneity, relate to the 5-FU response are ill-defined. This is largely due to a shortage of mechanistic studies in pre-clinical models able to recapitulate the key-features of CRC. Here, we analyzed the 5-FU response in human organoids genetically engineered to reproduce the different stages of CRC progression. We find that 5-FU induces pyrimidine imbalance, which leads to DNA damage and cell death. Actively proliferating cancer (stem) cells are, accordingly, efficiently targeted by 5-FU. Importantly, p53 behaves as a discriminating factor for 5-FU sensitivity, whereas p53-deficiency leads to DNA damage-induced cell death, active p53 protects from these effects through inducing cell cycle arrest. Moreover, we find that targeting the Warburg effect, by rewiring glucose metabolism, enhances 5-FU toxicity by altering the nucleotide pool and without increasing toxicity in non-transformed cells. Thus, rewiring glucose metabolism in combination with replication stress-inducing chemotherapies emerges as a promising strategy for CRC treatment.

Enteroendocrine cells (EECs) are gut epithelial cells that respond to intestinal contents by secreting hormones, including the incretins glucagon-like peptide 1 (GLP-1) and gastric inhibitory protein (GIP), which regulate multiple physiological processes. Hormone release is controlled through metabolite-sensing proteins. Low expression, interspecies differences, and the existence of multiple EEC subtypes have posed challenges to the study of these sensors. We describe differentiation of stomach EECs to complement existing intestinal organoid protocols. CD200 emerged as a pan-EEC surface marker, allowing deep transcriptomic profiling from primary human tissue along the stomach-intestinal tract. We generated loss-of-function mutations in 22 receptors and subjected organoids to ligand-induced secretion experiments. We delineate the role of individual human EEC sensors in the secretion of hormones, including GLP-1. These represent potential pharmacological targets to influence appetite, bowel movement, insulin sensitivity, and mucosal immunity.

No abstract is provided for this article.

&lt;div&gt;Abstract&lt;p&gt;A subset of patients with gastric cancer have mutations in genes that participate in or regulate Wnt signaling at the level of ligand (Wnt) receptor (Fzd) binding. Moreover, increased Fzd expression is associated with poor clinical outcome. Despite these findings, there are no &lt;i&gt;in vivo&lt;/i&gt; studies investigating the potential of targeting Wnt receptors for treating gastric cancer, and the specific Wnt receptor transmitting oncogenic Wnt signaling in gastric cancer is unknown. Here, we use inhibitors of Wnt/Fzd (OMP-18R5/vantictumab) and conditional gene deletion to test the therapeutic potential of targeting Wnt signaling in preclinical models of intestinal-type gastric cancer and &lt;i&gt;ex vivo&lt;/i&gt; organoid cultures. Pharmacologic targeting of Fzd inhibited the growth of gastric adenomas &lt;i&gt;in vivo&lt;/i&gt;. We identified Fzd7 to be the predominant Wnt receptor responsible for transmitting Wnt signaling in human gastric cancer cells and mouse models of gastric cancer, whereby Fzd7-deficient cells were retained in gastric adenomas but were unable to respond to Wnt signals and consequently failed to proliferate. Genetic deletion of &lt;i&gt;Fzd7&lt;/i&gt; or treatment with vantictumab was sufficient to inhibit the growth of gastric adenomas with or without mutations to &lt;i&gt;Apc&lt;/i&gt;. Vantictumab is currently in phase Ib clinical trials for advanced pancreatic, lung, and breast cancer. Our data extend the scope of patients that may benefit from this therapeutic approach as we demonstrate that this drug will be effective in treating patients with gastric cancer regardless of &lt;i&gt;APC&lt;/i&gt; mutation status.&lt;/p&gt;Significance:&lt;p&gt;The Wnt receptor Fzd7 plays an essential role in gastric tumorigenesis irrespective of &lt;i&gt;Apc&lt;/i&gt; mutation status, therefore targeting Wnt/Fzd7 may be of therapeutic benefit to patients with gastric cancer.&lt;/p&gt;&lt;/div&gt;

Orientation: Boredom at work has been shown to be a concern for individuals and organisations. At the time of this research, no validated scale was available to measure and investigate workplace boredom within the South African context.Research purpose: To determine the psychometric properties of the Dutch Boredom Scale (DUBS) within the South African context. Motivation for the study: No reliable and valid scale for workplace boredom was available in South Africa at the time of the current research. Boredom at work has been found to affect organisations negatively in other countries. Insights are needed into workplace boredom and how it affects the outcomes of organisations in South Africa. Research design, approach and method: A cross-sectional research approach was utilised. A random convenience sample (N = 490) was obtained from organisations within the manufacturing and logistics sector. In order to validate the DUBS, the factor structure, construct validity (convergent and discriminant validity) and scale reliability were investigated. A mediation model was also tested with structural equation modelling to ascertain predictive validity.Main findings: The results showed that the one-factor structure of the DUBS could be confirmed and that this factor had acceptable reliability. In terms of convergent validity, all of the item indicators loaded significantly on the workplace boredom construct, and the relationship between workplace boredom and work underload revealed that they were positively correlated with medium effect size. Furthermore, work engagement and organisational commitment were correlated negatively in terms of practical significance with workplace boredom. A structural mediation model showed that work underload was significantly and positively associated with boredom, which in turn had significant negative relations to both work engagement and organisational commitment. No significant direct relations were found from work underload to either work engagement or organisational commitment. Instead, bootstrapping showed that there was an indirect-only relationship from work underload to work engagement and organisational commitment through workplace boredom – indicating full mediation.Practical/managerial implications: Management should not neglect workplace boredom, as results indicate that it may adversely impact work engagement and organisational commitment. Therefore, workplace boredom should be a concern not only for individuals, but also for the organisation at large.Contribution/value-add: This study contributes to the limited research available on workplace boredom in South Africa by providing evidence of acceptable psychometric properties for a workplace boredom scale.

<h3>Introduction/Background</h3> Epithelial ovarian cancer is characterized by intratumour genetic heterogeneity, chemotherapy resistance and poor survival. The advent of ovarian cancer organoids, that recapitulate histological and genetic features of the original lesions, has providedopportunities for personalized assessment of drug response. Here, we assessed if the ovarian cancer organoid system can predict patients9 clinical response to chemotherapeutics. In addition, we evaluated the link between intratumour genetic heterogeneity and drug response using multiple organoids derived from individual patients. <h3>Methodology</h3> In total, we included 34 organoid lines derived from 22 patients with ovarian cancer at primary surgery or interval debulking. Organoid drug responses to chemotherapeutics as well as targeted drugs were determined. The IC50 and area under the curve values were computed from the drug response curves. Patients9 recurrence-free and overall survival were compared to the organoid drug response. For patients who received carboplatin and paclitaxel chemotherapy prior to interval debulking (N=7), we additionally compared organoid drug response to biochemical (CA125), pathological, radiological outcomes. The organoids and corresponding tumour tissues were subjected to whole genome sequencing for genomic analysis. <h3>Results</h3> Organoid drug response correlated to clinical response as defined by histopathological tumour assessment (chemotherapy response score (CRS)). Organoids of patients with no or minimal pathological response (CRS=1) were less sensitive to carboplatin and paclitaxelcompared to organoids of the patients with appreciable pathological response (CRS=2). The presumed additive effect of paclitaxel on carboplatin was only observed in a subset of organoids. Organoid exposure to eight additional drugs revealed that multiple tumour locations of the same patients exhibited varying responses to specific drugs. Genomic analyses are being performed to identify underlying mechanisms of differential drug responses. <h3>Conclusion</h3> Ovarian cancer organoids provide a valuable preclinical system with the potential to guide treatment choice through prediction of drug response, avoid unnecessary overtreatment and provide insights in response mechanisms. <h3>Disclosure</h3> No competing interests. Applicable funding sources: EIF | Stand Up To Cancer (SU2C) [Clevers, Kopper] KWF Kankerbestrijding (Dutch Cancer Society) - UU2015-7743 [de Witte, Witteveen, Zweemer, Kloosterman] Gieskes Strijbis Foundation (1816199) [Clevers, Witteveen, Kloosterman, Zweemer, Lõhmussaar, Espejo Valle-Inclan, Hami, Snippert]