Advanced statistics identification of participant and treatment predictors associated with severe adverse effects induced by fluoropyrimidine-based chemotherapy.

PURPOSE: Adverse effects following fluoropyrimidine-based chemotherapy regimens are common. However, there are no current accepted diagnostic markers for prediction prior to treatment, and the underlying mechanisms remain unclear. This study aimed to determine genetic and non-genetic predictors of adverse effects. METHODS: Genomic DNA was analyzed for 25 single nucleotide polymorphisms (SNPs). Demographics, comorbidities, cancer and fluoropyrimidine-based chemotherapy regimen types, and adverse effect data were obtained from clinical records for 155 Australian White participants. Associations were determined by bivariate analysis, logistic regression modeling and Bayesian network analysis. RESULTS: Twelve different adverse effects were observed in the participants, the most common severe adverse effect was diarrhea (12.9%). Bivariate analysis revealed associations between all adverse effects except neutropenia, between genetic and non-genetic predictors, and between 8 genetic and 12 non-genetic predictors with more than 1 adverse effect. Logistic regression modeling of adverse effects revealed a greater/sole role for six genetic predictors in overall gastrointestinal toxicity, nausea and/or vomiting, constipation, and neutropenia, and for nine non-genetic predictors in diarrhea, mucositis, neuropathy, generalized pain, hand-foot syndrome, skin toxicity, cardiotoxicity and fatigue. The Bayesian network analysis revealed less directly associated predictors (one genetic and six non-genetic) with adverse effects and confirmed associations between six adverse effects, eight genetic predictors and nine non-genetic predictors. CONCLUSION: This study is the first to link both genetic and non-genetic predictors with adverse effects following fluoropyrimidine-based chemotherapy. Collectively, we report a wealth of information that warrants further investigation to elucidate the clinical significance, especially associations with genetic predictors and adverse effects.

Antibiotic treatment targeting gram negative bacteria prevents neratinib-induced diarrhea in rats.

BACKGROUND: Neratinib is a pan-ErbB tyrosine kinase inhibitor used for extended adjuvant treatment of HER2-positive breast cancer. Diarrhea is the main adverse event associated with neratinib treatment. We aimed here to determine whether antibiotic-induced gut microbial shifts altered development of neratinib-induced diarrhea. METHODS: Female Albino Wistar rats (total n = 44) were given antibiotics (vancomycin, neomycin, or a cocktail of vancomycin, neomycin and ampicillin) in drinking water for four weeks, and then treated daily with neratinib (50 mg/kg) for 28 days. Diarrhea, along with markers of gastrointestinal damage and microbial alterations were measured by histopathology and 16S sequencing, respectively. RESULTS: Rats treated with vancomycin or neomycin had significantly lower levels of diarrhea than rats treated with neratinib alone. In the distal ileum, neratinib was associated with a statistically significant increase in histological damage in all treatment groups expect the antibiotic cocktail. Key features included villous blunting and fusion and some inflammatory infiltrate. Differences in microbial composition at necropsy in vehicle control, neratinib and neratinib + neomycin groups, were characterized by a neratinib-induced increase in gram-negative bacteria that was reversed by neomycin. Neomycin shifted bacterial composition so that Blautia become the dominant genus. CONCLUSIONS: Narrow spectrum antibiotics reduced neratinib-induced diarrhea. This suggests that the microbiome may play a key role in the development and prolongation of diarrhea following neratinib treatment, although further research is required to understand the key bacteria and mechanisms by which they reduce diarrhea, as well as how this may impact presentation of diarrhea in clinical cohorts.

The effect of free and encapsulated cisplatin into long-circulating and pH-sensitive liposomes on IEC-6 cells during wound healing in the presence of host-microbiota.

OBJECTIVES: To circumvent cisplatin (CDDP) toxic effects and improve the antitumoural effect, our research group developed long-circulating and pH-sensitive liposomes containing CDDP (SpHL-CDDP). This study aimed to evaluate whether SpHL-CDDP is associated with intestinal protection under in-vitro conditions in the presence of host-microbiota, compared with free CDDP. METHODS: The cytotoxicity of CDDP and SpHL-CDDP were evaluated by colorimetric MTT and sulforhodamine B (SRB) assays. Epithelial proliferation was assessed by using an in-vitro wounding model in the presence of host-microbiota with intestinal epithelial cell line 6 (IEC-6) monolayers. Cytokines were determined by ELISA. KEY FINDINGS: Reduced cytotoxicity of SpHL-CDDP in IEC-6 cells (minimum of 1.3-fold according to the IC50 values) was observed when compared with CDDP. The presence of microbiota or CDDP reduced the wound healing. The association of microbiota and SpHL-CDDP improved the wound healing and cell number in IEC-6 cells when compared with control. These beneficial results can be associated with increased IL-6 and IL-10 levels induced by SpHL-CDDP which were affected by the presence of microbiota. CONCLUSIONS: These results indicate that the presence of microbiota associated with SpHL-CDDP provided less intestinal cellular damages compared with CDDP and constitutes a promising candidate for clinical use.

Pathophysiology of neratinib-induced diarrhea in male and female rats: microbial alterations a potential determinant.

BACKGROUND: Neratinib is a potent irreversible pan-ErbB tyrosine kinase inhibitor, approved by the FDA for extended adjuvant treatment of HER2-positive breast cancer. Diarrhea is the most frequently observed adverse event with tyrosine kinase inhibitor therapy. In this study, we developed a reproducible model for neratinib-induced diarrhea in male and female rats. METHODS: At first, male rats were treated with neratinib at 15, 30 or 50 mg/kg or vehicle control via oral gavage for 28 days (total n = 12). Secondly, we compared outcomes of male (n = 7) and female (n = 8) rats, treated with 50 mg/kg neratinib. RESULTS: Rats treated with a 50 mg/kg daily dose of neratinib had a reproducible and clinically relevant level of diarrhea and therefore was confirmed as an appropriate dose. Male rats treated with neratinib had significant changes to their gut microbiome. This included neratinib-induced increases in Ruminococcaceae (P = 0.0023) and Oscillospira (P = 0.026), and decreases in Blautia (P = 0.0002). On average, female rats experienced more significant neratinib-induced diarrhea (mean grade 1.526) compared with male rats (mean grade 1.182) (P < 0.0001). Neratinib caused a reduction in percentage weight gain after 28 days of treatment in females (P = 0.0018) compared with vehicle controls. Females and males both showed instances of villus atrophy and fusion, most severely in the distal ileum. Serum neratinib concentration was higher in female rats compared to male rats (P = 0.043). CONCLUSIONS: A reproducible diarrhea model was developed in both female and male rats, which indicated that diarrhea pathogenesis is multifactorial, including anatomical disruption particularly evident in the distal ileum, and alterations in microbial composition.

Serum outperforms plasma in small extracellular vesicle microRNA biomarker studies of adenocarcinoma of the esophagus.

BACKGROUND: Circulating microRNAs (miRNAs) are potential biomarkers for many diseases. However, they can originate from non-disease specific sources, such as blood cells, and compromise the investigations for miRNA biomarkers. While small extracellular vesicles (sEVs) have been suggested to provide a purer source of circulating miRNAs for biomarkers discovery, the most suitable blood sample for sEV miRNA biomarker studies has not been defined. AIM: To compare the miRNA profiles between matched serum and plasma sEV preparations to determine their suitability for biomarker studies. METHODS: Matched serum and plasma samples were obtained from 10 healthy controls and 10 patients with esophageal adenocarcinoma. sEV isolates were prepared from serum and plasma using ExoQuickTM and quantified using NanoSight. RNA was extracted from sEV preparations with the miRNeasy Serum/Plasma kit and profiled using the Taqman Openarray qPCR. The overall miRNA content and the expression of specific miRNAs of reported vesicular and non-vesicular origins were compared between serum and plasma sEV preparations. The diagnostic performance of a previously identified multi-miRNA biomarker panel for esophageal adenocarcinoma was also compared. RESULTS: The overall miRNA content was higher in plasma sEV preparations (480 miRNAs) and contained 97.5% of the miRNAs found in the serum sEV preparations (412 miRNAs).The expression of commonly expressed miRNAs was highly correlated (Spearman's R = 0.87, P < 0.0001) between the plasma and serum sEV preparations, but was consistently higher in the plasma sEV preparations. Specific blood-cell miRNAs (hsa-miR-223-3p, hsa-miR-451a, miR-19b-3p, hsa-miR-17-5p, hsa-miR-30b-5p, hsa-miR-106a-5p, hsa-miR-150-5p and hsa-miR-92a-3p) were expressed at 2.7 to 9.6 fold higher levels in the plasma sEV preparations compared to serum sEV preparations (P < 0.05). In plasma sEV preparations, the percentage of protein-associated miRNAs expressed at relatively higher levels (Ct 20-25) was greater than serum sEV preparations (50% vs 31%). While the percentage of vesicle-associated miRNAs expressed at relatively higher levels was greater in the serum sEV preparations than plasma sEV preparations (70% vs 44%). A 5-miRNA biomarker panel produced a higher cross validated accuracy for discriminating patients with esophageal adenocarcinoma from healthy controls using serum sEV preparations compared with plasma sEV preparations (AUROC 0.80 vs 0.54, P < 0.05). CONCLUSION: Although plasma sEV preparations contained more miRNAs than serum sEV preparations, they also contained more miRNAs from non-vesicle origins. Serum appears to be more suitable than plasma for sEV miRNAs biomarkers studies.

The GLP-2 analogue elsiglutide reduces diarrhoea caused by the tyrosine kinase inhibitor lapatinib in rats.

PURPOSE: Lapatinib is a small molecule tyrosine kinase inhibitor used to treat breast cancer, often in combination with chemotherapy. Diarrhoea commonly occurs in up to 78% of patients undertaking lapatinib treatment. The mechanism of this diarrhoea is currently unknown. Elsiglutide is a GLP-2 analogue known to increase cell proliferation and reduce apoptosis in the intestine. METHODS: We used a previously developed rat model of lapatinib-induced diarrhoea to determine if co-treatment with elsiglutide was able to reduce diarrhoea caused by lapatinib. Additionally, we analysed the caecal microbiome of these rats to assess changes in the microbiome due to lapatinib. RESULTS: Rats treated with lapatinib and elsiglutide had less severe diarrhoea than rats treated with lapatinib alone. Serum lapatinib levels, blood biochemistry, myeloperoxidase levels and serum limulus amebocyte lysate levels were not significantly different between groups. Rats treated with lapatinib alone had significantly higher histopathological damage in the ileum than vehicle controls. This increase was not seen in rats also receiving elsiglutide. Rats receiving lapatinib alone had lower microbial diversity than rats who also received elsiglutide. CONCLUSIONS: Elsiglutide was able to reduce diarrhoea from lapatinib treatment. This does not appear to be via reduction in inflammation or barrier permeability, and may be due to thickening of mucosa, leading to increased surface area for fluid absorption in the distal small intestine. Microbial changes seen in this study require further research to fully elucidate their role in the development of diarrhoea.

Potential Successes and Challenges of Targeted Cancer Therapies.

The concept and realization of targeted anticancer therapy (TAT) have existed for at least two decades and continue to expand rapidly. It has become clear that there is no "magic bullet" to cure cancer and that even TATs are unlikely to be successful as single agents, necessitating combination with chemotherapy, radiotherapy, or even other targeting agents. The other promise that has not been fulfilled by TAT is that of reduced toxicity. It was thought that by targeting receptors on or within cells, rather than particular phases of the cell cycle, TATs would not be toxic. However, it turns out that the targets also exist on or within normal cells and that there is even cross-reactivity between receptors on nontarget tissues. All of this results in toxicity, the mechanism of which are the same as the mechanism of action of the drugs, making toxicity reduction or prevention very difficult. This leads to new toxicities with new targeted treatments. Nevertheless, all of the above should not detract from the obvious successes of targeted agents, which have turned several acutely fatal cancers into chronic diseases and rendered some hitherto untreatable cancers into treatable diseases.

Oral Mucositis Due to High-Dose Chemotherapy and/or Head and Neck Radiation Therapy.

Oral mucositis is a common side-effect associated with conventional cancer therapy and has also recently been reported in association with newly emerging cancer therapies. It is characterized as an inflammation of the oral mucous membranes accompanied by many complex mucosal and submucosal changes. Ulcerative oral mucositis can cause significant oral pain, impair nutritional intake, lead to local or systemic infection, and cause significant economic cost. In addition, it may necessitate interruptions in cancer therapy, thus adversely affecting patient prognosis. This review presents the current understanding of the pathogenesis of mucositis and discusses evidence-based clinical management strategies for oral mucositis. In addition, key research questions for future investigation are identified, followed by a discussion of strategies to promote development and funding of the needed research.

Individual or combination treatments with lapatinib and paclitaxel cause potential bone loss and bone marrow adiposity in rats.

Cancer treatments with cytotoxic drugs have been shown to cause bone loss. However, effects on bone are less clear for ErbB-targeting tyrosine kinase inhibitors or their combination use with cytotoxic drugs. This study examined the effects of individual or combination treatments with breast cancer drugs lapatinib (a dual ErbB1/ErbB2 inhibitor) and paclitaxel (a microtubule-stabilizing cytotoxic agent) on bone and bone marrow of rats. Wistar rats received lapatinib (240 mg/kg) daily, paclitaxel (12 mg/kg) weekly, or their combination for 4 weeks, and effects on bone/bone marrow were examined at the end of week 4. Microcomputed tomographical structural analyses showed a reduction in trabecular bone volume in tibia following the lapatinib, paclitaxel or their combination treatments ( P < 0.05). Histomorphometry analyses revealed marked increases in bone marrow adipocyte contents in all treatment groups. Reverse transcription polymerase chain reaction gene expression studies with bone samples and cell culture studies with isolated bone marrow stromal cells showed that the all treatment groups displayed significantly reduced levels of osterix expression and osteogenic differentiation potential but increased expression levels of adipogenesis transcription factor peroxisome proliferator-activated receptor γ. In addition, these treatments suppressed the expression of Wnt10b and/or increased expression of Wnt antagonists (secreted frizzled-related protein 1, Dickkopf-related protein 1 and/or sclerostin). Furthermore, all treatment groups showed increased numbers of bone-resorbing osteoclasts on trabecular bone surfaces, although only the lapatinib group displayed increased levels of osteoclastogenic signal (receptor activator of nuclear factor κΒ ligand/osteoclastogenesis inhibitor osteoprotegrin expression ratio) in the bones. Thus, inhibiting ErbB1 and ErbB2 by lapatinib or blocking cell division by paclitaxel or their combination causes significant trabecular bone loss and bone marrow adiposity involving a switch in osteogenesis/adipogenesis potential, altered expression of some major molecules of the Wnt/ß-catenin signalling pathway, and increased recruitment of bone-resorbing osteoclasts.

Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFß), angiostatin, and endostatin are increased in radiotherapy-induced gastrointestinal toxicity.

PURPOSE: Radiotherapy-induced gut toxicity (RIGT) is a debilitating effect of radiotherapy for cancer, often resulting in significant diarrhea and pain. Previous studies have highlighted roles of the intestinal microvasculature and matrix metalloproteinases (MMPs) in the development of RIGT. We hypothesized vascular mediators would be significantly altered in a dark agouti (DA) rat model of RIGT. Additionally, we aimed to assess the effect of MMP-2 and -9 inhibition on the response of tumor-associated microvascular endothelial cells (TAMECs) to radiation. METHODS: DA rats were administered 2.5 Gy abdominal irradiation (3 times/week over 6 weeks). Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFß), von Willebrand factor (VWF), angiostatin, and endostatin expression was assessed at 3, 6, and 15 weeks. Additionally, DA rat mammary adenocarcinoma tumor-associated microvascular endothelial cells (TAMECs) were used to assess the effects of radiation (12 Gy) and the MMP inhibitor SB-3CT on MMP, VEGF, and TGFß expression, and cell viability. RESULTS: VEGF mRNA expression was significantly increased in the colon at week 15 (p = .0012), and TGFß mRNA expression was significantly increased in both the jejunum and colon at week 3 (p = .0280 and p = .0310, respectively). Endostatin immunostaining was significantly increased at week 3 (p = .0046), and angiostatin at 3 and 6 weeks (p = .0022 and p = .0135, respectively). MMP-2 and -9 mRNA and total protein levels were significantly increased following irradiation of TAMECs. Although this increase was significantly attenuated by SB-3CT, it did not significantly alter endothelial cell viability or VEGF and TGFß mRNA expression. CONCLUSIONS: Findings of this study support the involvement of VEGF, TGFß, angiostatin, endostatin, and MMP-2 in the pathobiology of RIGT. However, the relationship between these mediators is complex and needs further investigation to improve understanding of their therapeutic potential in RIGT.

Matrix metalloproteinase expression is altered in the small and large intestine following fractionated radiation in vivo.

PURPOSE: Radiotherapy-induced gut toxicity (RIGT) is associated with significant diarrhoea, pain and rectal bleeding. Matrix metalloproteinases (MMPs) have been reported to be involved in chemotherapy-induced gut toxicity and RIGT following single-dose irradiation in vivo. We therefore proposed MMPs would be involved in the pathobiology of RIGT following fractionated irradiation. METHODS: Dark Agouti rats were treated with fractionated radiation (3 × 2.5 Gy/week for 6 weeks). Rats were killed at 3, 6 and 15 weeks to represent acute and chronic toxicities. Sections of jejunum and colon were immunostained for MMP-1, MMP-2, MMP-9 and MMP-14. Relative mRNA expression in jejunum and colon was quantified by RT-PCR for MMP-1, MMP-2, MMP-9 and MMP-14. Western blotting was also conducted on jejunum and colon tissue collected at week 6 to determine protein levels of pro- and active MMP-2. RESULTS: MMP-2 total protein levels, determined by western blotting, significantly increased in both the jejunum (p = 0.0359) and the colon (p = 0.0134) 6 weeks into the fractionated radiation schedule. MMP-1, MMP-2, and MMP-14 mRNA expression significantly increased in the jejunum. MMP-2 mRNA expression was also significantly increased in the colon. Immunostaining of MMP-2 was observed to be increased in both crypt enterocytes and the lamina propria. CONCLUSIONS: MMP-2 plays a role in the pathobiology of gastrointestinal toxicities following fractionated irradiation. Whilst MMP-1 and MMP-14 mRNA expression was increased, this occurred only in the jejunum, suggesting MMPs are differentially involved in RIGT depending on the intestinal region. Further studies are needed to elucidate the role these mediators play in the development and potentiation of RIGT.

Dacomitinib-induced diarrhea: Targeting chloride secretion with crofelemer.

Dacomitinib, an irreversible small-molecule pan-ErbB TKI, has a high incidence of diarrhea, which has been suggested to be due to chloride secretory mechanisms. Based on this hypothesis, crofelemer, an antisecretory agent may be an effective intervention. T84 monolayers were treated with 1 µM dacomitinib and 10 µM crofelemer, and mounted into Ussing chambers for electrogenic ion analysis. Crofelemer attenuated increases in chloride secretion in cells treated with dacomitinib. Albino Wistar rats (n = 48) were treated with 7.5 mg/kg dacomitinib and/or 25 mg/kg crofelemer via oral gavage for 21 days. Crofelemer significantly worsened dacomitinib-induced diarrhea (p = 0.0003), and did not attenuate weight loss (p < 0.0001). Sections of the ileum and colon were mounted into Ussing chambers, and secretory processes analyzed. This indicated that crofelemer lost its anti-secretory action in the presence of dacomitinib in this model. Mass spectrometry revealed that crofelemer did not change serum concentration of dacomitinib. Serum FITC dextran levels indicated that crofelemer was unable to attenuate dacomitinib-induced barrier dysfunction. Tight junction proteins were visualized with immunofluorescence. Qualitative analysis showed dacomitinib induced proteolysis of ZO-1 and occludin, and internalization of claudin-1, which was not attenuated by crofelemer. Detailed histopathological analysis showed that crofelemer was unable to attenuate dacomitinib-induced ileal damage. Crofelemer worsened dacomitinib-induced diarrhea, suggesting that antisecretory drug therapy may be ineffective in this setting.

Combination breast cancer chemotherapy with doxorubicin and cyclophosphamide damages bone and bone marrow in a female rat model.

PURPOSE: Anthracyclines (including doxorubicin) are still the backbone of commonly used breast cancer chemotherapy regimens. Despite increasing use of doxorubicin and cyclophosphamide (AC) combinations for treating breast cancer, their potential to cause adverse skeletal effects remains unclear. METHODS: This study examined the effects of treatments with the AC regimen on bone and bone marrow in adult female rats. RESULTS: AC treatment for four cycles (weekly intravenous injection of 2 mg/kg doxorubicin and 20 mg/kg cyclophosphamide) resulted in a reduced volume of trabecular bone at the metaphysis, which was associated with reduced serum levels of 25-hydroxy vitamin D3 and alkaline phosphatase. Reductions in densities of osteocytes and bone lining cells were also observed. In addition, bone marrow was severely damaged, including a severe reduction in bone marrow cellularity and an increase in marrow adipocyte content. Accompanying these changes, there were increases in mRNA expression of adipogenesis regulatory genes (PPARγ and FABP4) and an inflammatory cytokine (TNFα) in metaphysis bone and bone marrow. CONCLUSIONS: This study indicates that AC chemotherapy may induce some bone loss, due to reduced bone formation, and bone marrow damage, due to increased marrow adiposity. Preventive strategies for preserving the bone and bone marrow microenvironment during anthracycline chemotherapy warrant further investigation.

Impact of a planned dose interruption of dacomitinib in the treatment of advanced non-small-cell lung cancer (ARCHER 1042).

OBJECTIVES: Dacomitinib is a pan-HER inhibitor for advanced non-small-cell lung cancer (NSCLC). We explored the impact of a planned 4-day dacomitinib dose interruption on plasma exposure of dacomitinib and adverse events (AEs) of interest in Cohort III of the ARCHER 1042 study. MATERIALS AND METHODS: Patients, treatment-naïve for advanced NSCLC with EGFR activating mutations, received oral dacomitinib 45mg QD (once daily). A planned dose interruption occurred in Cycle 1 from Days 11 through 14. The primary endpoint was the pharmacokinetic (PK) characteristics of dacomitinib in Cycle 1Day 10 and during dose interruption. Secondary endpoints included safety and concomitant medications used to treat AEs of interest. RESULTS: Cohort III enrolled 25 patients. Median plasma Cmax of dacomitinib in Cycle 1 Day 10 was 83.40ng/mL. Average median plasma dacomitinib concentration during the 4-day dose interruption was 42.63ng/mL. In the first 8 weeks of treatment 1) 80% of patients used concomitant medications for dermatologic AEs, 76% for diarrhea, and 44% for stomatitis, and 2) all patients experienced treatment-emergent AEs and 28% had all-causality Grade 3 AEs. CONCLUSION: At 45mg QD dosing, PK parameters of plasma dacomitinib in Cycle 1 Day 10 were comparable to that obtained in Cycle 1 Day 14 from other dacomitinib studies. Average median plasma dacomitinib concentration during the 4-day dose interruption was approximately half of the median plasma Cmax of dacomitinib observed prior to dose interruption. The toxicity profile was consistent with that from other studies of dacomitinib.

Dacomitinib-induced diarrhoea is associated with altered gastrointestinal permeability and disruption in ileal histology in rats.

Dacomitinib-an irreversible pan-ErbB tyrosine kinase inhibitor (TKI)-causes diarrhoea in 75% of patients. Dacomitinib-induced diarrhoea has not previously been investigated and the mechanisms remain poorly understood. The present study aimed to develop an in-vitro and in-vivo model of dacomitinib-induced diarrhoea to investigate underlying mechanisms. T84 cells were treated with 1-4 µM dacomitinib and resistance and viability were measured using transepithelial electrical resistance (TEER) and XTT assays. Rats were treated with 7.5 mg/kg dacomitinib daily via oral gavage for 7 or 21 days (n = 6/group). Weights, and diarrhoea incidence were recorded daily. Rats were administered FITC-dextran 2 hr before cull, and serum levels of FITC-dextran were measured and serum biochemistry analysis was conducted. Detailed histopathological analysis was conducted throughout the gastrointestinal tract. Gastrointestinal expression of ErbB1, ErbB2 and ErbB4 was analysed using RT-PCR. The ileum and the colon were analysed using multiplex for expression of various cytokines. T84 cells treated with dacomitinib showed no alteration in TEER or cell viability. Rats treated with dacomitinib developed severe diarrhoea, and had significantly lower weight gain. Further, dacomitinib treatment led to severe histopathological injury localised to the ileum. This damage coincided with increased levels of MCP1 in the ileum, and preferential expression of ErbB1 in this region compared to all other regions. This study showed dacomitinib induces severe ileal damage accompanied by increased MCP1 expression, and gastrointestinal permeability in rats. The histological changes were most pronounced in the ileum, which was also the region with the highest relative expression of ErbB1.

Fractionated abdominal irradiation induces intestinal microvascular changes in an in vivo model of radiotherapy-induced gut toxicity.

PURPOSE: Radiotherapy-induced gut toxicity (RIGT) is associated with diarrhoea, pain and rectal bleeding and can occur as an acute or chronic toxicity. The microvasculature has been shown to be altered in the development of RIGT; however, the features are not yet characterized. We hypothesized that apoptosis of microvascular cells would occur early in the gastrointestinal tract following fractionated irradiation, followed by late microvascular changes, including sclerosis and telangiectasis. METHODS: Female Dark Agouti rats were treated with a 6-week fractionated radiation schedule of 3 × 2.5 Gy doses per week localized to the abdomen. At 3, 6 and 15 weeks, the intestines were assessed for markers of acute and chronic injury including morphological changes, collagen deposition, apoptosis and proliferation. RESULTS: Apoptosis of microvascular cells significantly increased at 6 and 15 weeks in the jejunum (p = 0.0026 and p = 0.0062, respectively) and at 6 and 15 weeks in the colon (p < 0.0001 and p = 0.0005, respectively) in rats receiving fractionated radiation to the abdomen. Histopathological changes of the colon microvasculature were also seen from week 3, including thickening of the lamina propria and dilated, thickened, telangiectatic vessels. CONCLUSIONS: Findings of this study provide evidence of regional and timing-specific changes in the intestinal microvasculature in response to fractionated radiotherapy which may play a role in development of both acute and chronic RIGT.

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

PURPOSE: A 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. METHODS: This is a review of current literature on irinotecan-induced mucositis and GLP-2 analogues mechanisms of action. RESULTS: Recent 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. CONCLUSION: This 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.

Methotrexate-induced toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses.

PURPOSE: Methotrexate chemotherapy is associated with various toxicities which can result in the interruption or discontinuation of treatment and a subsequently raised risk of relapse. This umbrella systematic review was conducted to synthesize the results of all existing systematic reviews that investigate the pharmacogenetics of methotrexate-induced toxicity, with the aim of developing a comprehensive reference for personalized medicine. METHODS: Databases searched were PubMed, Embase, JBI Database of Systematic Reviews and Implementation Reports, DARE, and ProQuest. Papers were critically appraised by two reviewers, and data were extracted using a standardized tool. RESULTS: Three systematic reviews on methotrexate-induced toxicity were included in the review. Meta-analyses were reported across Asian, Caucasian, pediatric and adult patients for the MTHFR C677T and A1298C polymorphisms. Toxicity outcomes included different forms of hematologic, ectodermal and hepatic toxicities. Results varied considerably depending on the patient groups and subgroups investigated in the different systematic reviews, as well as the genetic models utilized. However, significant associations were found between the MTHFR C677T allele and; hepatic toxicity, myelosuppression, oral mucositis, gastrointestinal toxicity, and skin toxicity. Additionally, limited evidence suggests that the MTHFR A1298C polymorphism may be associated with decreased risk of skin toxicity and leukopenia. CONCLUSION: This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of methotrexate toxicity. The next step in making personalized medicine for methotrexate therapy a clinical reality is research on the effectiveness and cost-effectiveness of MTHFR genotype testing to enable the close monitoring of at-risk patients for the timely initiation of rescue therapies.

Radiotherapy-induced gut toxicity: Involvement of matrix metalloproteinases and the intestinal microvasculature.

Purpose To review the literature surrounding the involvement of the endothelium and matrix metalloproteinases (MMP) in radiotherapy-induced gut toxicity (RIGT) and further elucidate its complex pathobiology. Results RIGT involves damage to the gastrointestinal mucosa and is associated with diarrhoea, pain, and rectal bleeding depending on the area of exposure. The mechanisms underpinning RIGT are complex and have not yet been elucidated. Members of the MMP family, particularly MMP-2 and -9, have recently been identified as being key markers in RIGT and chemotherapy-induced gut toxicity (CIGT). Furthermore, the microvasculature has long been implicated in the development of toxicities following both chemotherapy and radiotherapy, however, the mechanisms behind this are yet to be explored. Conclusions It is proposed that matrix metalloproteinases are key regulators of endothelial mediators, and may play a key role in inducing damage to intestinal microvasculature following radiotherapy.

Fluoropyrimidine and platinum toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses.

Fluoropyrimidine (FU) and platinum-based chemotherapies are greatly complicated by their associated toxicities. This umbrella systematic review synthesized all systematic reviews that investigated associations between germline variations and toxicity, with the aim of informing personalized medicine. Systematic reviews are important in pharmacogenetics where false positives are common. Four systematic reviews were identified for FU-induced toxicity and three for platinum. Polymorphisms of DPYD and TYMS, but not MTHFR, were statistically significantly associated with FU-induced toxicity (although only DPYD had clinical significance). For platinum, GSTP1 was found to not be associated with toxicity. This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of FU and platinum toxicity. It provides a useful reference for clinicians and identifies important research gaps.