Bronwen Mayo

Nutlin-3a efficacy in sarcoma predicted by transcriptomic and epigenetic profiling

Nutlin-3a is a small-molecule antagonist of p53/MDM2 that is being explored as a treatment for sarcoma. In this study, we examined the molecular mechanisms underlying the sensitivity of sarcomas to Nutlin-3a. In an ex vivo tissue explant system, we found that TP53 pathway alterations (TP53 status, MDM2/MDM4 genomic amplification/mRNA overexpression, MDM2 SNP309, and TP53 SNP72) did not confer apoptotic or cytostatic responses in sarcoma tissue biopsies (n = 24). Unexpectedly, MDM2 status did not predict Nutlin-3a sensitivity. RNA sequencing revealed that the global transcriptomic profiles of these sarcomas provided a more robust prediction of apoptotic responses to Nutlin-3a. Expression profiling revealed a subset of TP53 target genes that were transactivated specifically in sarcomas that were highly sensitive to Nutlin-3a. Of these target genes, the GADD45A promoter region was shown to be hypermethylated in 82% of wild-type TP53 sarcomas that did not respond to Nutlin-3a, thereby providing mechanistic insight into the innate ability of sarcomas to resist apoptotic death following Nutlin-3a treatment. Collectively, our findings argue that the existing benchmark biomarker for MDM2 antagonist efficacy (MDM2 amplification) should not be used to predict outcome but rather global gene expression profiles and epigenetic status of sarcomas dictate their sensitivity to p53/MDM2 antagonists.

Development of a rat model of oral small molecule receptor tyrosine kinase inhibitor-induced diarrhea

Orally administered small molecule receptor tyrosine kinase inhibitors (RTKIs) are increasingly common treatments for cancer, both alone and in combination with chemotherapy. However, their side effect profiles and the underlying mechanisms of such are not yet fully elucidated. Management of their most common dose limiting side effect, diarrhea, has been hampered by a lack of suitable animal models. We aimed to develop a clinically relevant rat model of RTKI-induced diarrhea that could be utilized for investigating supportive care interventions and pharmacokinetics. Albino Wistar rats were treated daily for 4 weeks with various concentrations of lapatinib to determine the optimal dose for development of diarrhea. This was then followed by an experiment with addition of paclitaxel once weekly for 4 weeks to observe effects of combination drug treatment on diarrhea. Data regarding animal tolerance to the treatment, organ weights, circulating lapatinib concentration and histopathology were collected weekly. Lapatinib caused diarrhea in rats that was dose-dependent. Diarrhea occurred without causing significant intestinal histopathology. Follow up experiments are currently underway to determine the exact pathogenesis and mechanisms of lapatinib-induced diarrhea and potential protective strategies.

Dark Agouti rat model of chemotherapy-induced mucositis: Establishment and current state of the art:

Mucositis is a major oncological problem. The entire gastrointestinal and genitourinary tract and also other mucosal surfaces can be affected in recipients of radiotherapy, and/or chemotherapy. Major progress has been made in recent years in understanding the mechanisms of oral and small intestinal mucositis, which appears to be more prominent than colonic damage. This progress is largely due to the development of representative laboratory animal models of mucositis. This review focuses on the development and establishment of the Dark Agouti rat mammary adenocarcinoma model by the Mucositis Research Group of the University of Adelaide over the past 20 years to characterize the mechanisms underlying methotrexate-, 5-fluorouracil-, and irinotecan-induced mucositis. It also aims to summarize the results from studies using different animal model systems to identify new molecular and cellular markers of mucositis.

Investigation of effect of nutritional drink on chemotherapy-induced mucosal injury and tumor growth in an established animal model.

Chemotherapy-induced mucositis represents a significant burden to quality of life and healthcare costs, and may be improved through enhanced nutritional status. We first determined the safety of two nutritional drinks (plus placebo), and then potential gut protection in tumor-bearing rats in a model of methotrexate-induced mucositis. In study 1, animals were fed one of two test diets (or placebo or control chow pellets) for a total of 60 days and were monitored daily. All diets were found to be safe to administer. In study 2, after seven days of receiving diets, a Dark Agouti Mammary Adenocarcinoma (DAMA) was transplanted subcutaneously. Ten days after starting diets, animals had 2 mg/kg intramuscular methotrexate administered on two consecutive days; after this time, all animals were given soaked chow. Animals were monitored daily for changes in bodyweight, tumor burden and general health. Animals were killed 10, 12 and 16 days after initially starting diets, and tissues were collected at necropsy. In study 1, animals receiving diets had gained 0.8% and 10.8% of their starting bodyweight after 60 days, placebo animals 4.4%, and animals fed on standard chow had gained 15.1%. In study 2, there was no significant influence of test diet on bodyweight, organ weight, tumor burden or biochemical parameters. Only animals treated with MTX exhibited diarrhea, although animals receiving Diet A and Diet C showed a non-significant increase in incidence of diarrhea. Administration of these nutritional drinks did not improve symptoms of mucositis.

Irinotecan-induced mucositis: the interactions and potential role of GLP-2 analogues

PurposeA common side effect of irinotecan administration is gastrointestinal mucositis, often manifesting as severe diarrhoea. The damage to the structure and function of the gastrointestinal tract caused by this cytotoxic agent is debilitating and often leads to alterations in patients’ regimens, hospitalisation or stoppage of treatment. The purpose of this review is to identify mechanisms of irinotecan-induced intestinal damage and a potential role for GLP-2 analogues for intervention.MethodsThis is a review of current literature on irinotecan-induced mucositis and GLP-2 analogues mechanisms of action.ResultsRecent studies have found alterations that appear to be crucial in the development of severe intestinal mucositis, including early apoptosis, alterations in proliferation and cell survival pathways, as well as induction of inflammatory cascades. Several studies have indicated a possible role for glucagon-like peptide-2 analogues in treating this toxicity, due to its proven intestinotrophic, anti-apoptotic and anti-inflammatory effects in other models of gastrointestinal disease.ConclusionThis review provides evidence as to why and how this treatment may improve mucositis through the possible molecular crosstalk that may be occurring in models of severe intestinal mucositis.

Further characterisation of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor-induced diarrhoea

Objectives: A pharmacoinformatics tool was employed in this prospective, cohort study to determine its utility in identifying risk factors that are useful as predictors of chemotherapy-induced nausea and vomiting (CINV). Methods: Asian patients on a variety of chemotherapy regimens and appropriate antiemetic treatment were recruited from January 2007–July 2010. CINV events were recorded using a CINV diary. Pharmacoinformatics analysis involved principal component analysis of 12 risk factors to differentiate patients with and without complete response (CR), complete protection (CP) and complete control (CC). Results: 710 patients were recruited. Mean age was 52.9±10.3 years. Majority were females (67%) and Chinese (84%). Patient proportions that achieved CR, CP and CC were 58%, 42% and 27% respectively. Five risk factors were identified as potential predictors of these endpoints. Period of alcohol drinking and history of CIV were predictive in cisplatin-based regimens, while drinking frequency and history of CIN were predictive in anthracycline-based and oxaliplain-based regimens. Fatigue interference was a better predictor than severity generally Conclusions: This study has successfully utilized a pharmacoinformatics tool to pinpoint 5 clinical predictors in patients whose CINV are not well managed. Future research should further optimize antiemetic therapies in these populations.S Support Care Cancer (2011) 19 (Suppl 2):S67–S370 DOI 10.1007/s00520-011-1184-yObjectives: Patients with and without CINV report different anxiety symptoms. This study utilized a novel pharmacoinformatics approach to identify anxiety symptoms that could predict chemotherapy-induced nausea and vomiting (CINV) based on a 21-item objective assessment tool (Beck Anxiety Inventory). Methods: Asian patients on a variety of chemotherapy regimens and appropriate antiemetic treatment were recruited from January 2007–July 2010. CINV events were recorded in a CINV diary. The principal variable (PV) approach was used for pharmacoinformatic analysis of 21 anxiety symptoms to differentiate patients with and without complete response (CR), complete protection (CP) and complete control (CC). Results: 710 patients were recruited. Mean age was 52.9±10.3 years. Majority were females (67%) and Chinese (84%). Patient proportions that achieved CR, CP and CC were 58%, 42% and 27% respectively. Seven items (33%) were identified as clinical predictors of the CINV endpoints. ‘Fear of dying’ was a predictor for CINV in head-and-neck and gastrointestinal cancer patients receiving platinum-based chemotherapies. In addition, ‘hot/cold sweats’ was associated with head-and-neck cancer patients, while ‘nervousness’ and ‘faintness’ were mainly observed in gastrointestinal cancer patients. On the other hand, ‘fear of the worst’, ‘numbness’ and ‘unable to relax’ predicted for poor CINV control in breast cancer patients receiving anthracycline-based chemotherapies. Conclusions: This study has successfully demonstrated that anxiety symptoms vary among patients who experience different cancers. They may experience different efficacy outcomes with their antiemetics. The PV approach is able to identify 7 anxiety-associated symptoms that can be clinically-relevant when assessing CINV risks among cancer patients.

Apoptosis, proliferation and inflammation are improved after treatment with the new selective glp-2 receptor agonist, elsiglutide, in a rat model of irinotecan-induced mucositis

Paul A James, Lara Petelin, Ian Campbell, Hugh Dawkins, Stephen Fox, Janet Hiller, Judy Kirk, Geoffrey Lindeman, Finlay Macrae, Lyon Mascarenhas, Julie McGaughran, Bettina Meiser, April Morrow, Cassandra Nichols, Nicholas Pachter, Christobel Saunders, Clare Scott, Nicola Poplawski, Letitia Thrupp, Alison Trainer, Robyn Ward, Mary-Anne Young, Gillian Mitchell

The new selective glp-2 receptor agonist, elsiglutide, improves irinotecan-induced diarrhoea and mucositis in the rat

Paul A James, Lara Petelin, Ian Campbell, Hugh Dawkins, Stephen Fox, Janet Hiller, Judy Kirk, Geoffrey Lindeman, Finlay Macrae, Lyon Mascarenhas, Julie McGaughran, Bettina Meiser, April Morrow, Cassandra Nichols, Nicholas Pachter, Christobel Saunders, Clare Scott, Nicola Poplawski, Letitia Thrupp, Alison Trainer, Robyn Ward, Mary-Anne Young, Gillian Mitchell

The effect of oral microbes on the proliferation, healing, and immune response of intestinal epithelial cells (IEC6) treated with SN-38 (metabolite of irinotecan)

Paul A James, Lara Petelin, Ian Campbell, Hugh Dawkins, Stephen Fox, Janet Hiller, Judy Kirk, Geoffrey Lindeman, Finlay Macrae, Lyon Mascarenhas, Julie McGaughran, Bettina Meiser, April Morrow, Cassandra Nichols, Nicholas Pachter, Christobel Saunders, Clare Scott, Nicola Poplawski, Letitia Thrupp, Alison Trainer, Robyn Ward, Mary-Anne Young, Gillian Mitchell