Gastrointestinal mucositis

Chemotherapy-induced diarrhea: pathophysiology, frequency and guideline-based management

Diarrhea is one of the main drawbacks for cancer patients. Possible etiologies could be radiotherapy, chemotherapeutic agents, decreased physical performance, graft versus host disease and infections. Chemotherapy-induced diarrhea (CID) is a common problem, especially in patients with advanced cancer. The incidence of CID has been reported to be as high as 50-80% of treated patients (≥30% CTC grade 3-5), especially with 5-fluorouracil bolus or some combination therapies of irinotecan and fluoropyrimidines (IFL, XELIRI). Regardless of the molecular targeted approach of tyrosine kinase inhibitors and antibodies, diarrhea is a common side effect in up to 60% of patients with up to 10% having severe diarrhea. Furthermore, the underlying pathophysiology is still under investigation. Despite the number of clinical trials evaluating therapeutic or prophylactic measures in CID, there are just three drugs recommended in current guidelines: loperamide, deodorized tincture of opium and octreotide. Newer strategies and more effective agents are being developed to reduce the morbidity and mortality associated with CID. Recent research focusing on the prophylactic use of antibiotics, budesonide, probiotics or activated charcoal still have to define the role of these drugs in the routine clinical setting. Whereas therapeutic management and clinical work-up of patients presenting with diarrhea after chemotherapy are rather well defined, prediction and prevention of CID is an evolving field. Current research focuses on establishing predictive factors for CID like uridine diphosphate glucuronosyltransferase-1A1 polymorphisms for irinotecan or dihydropyrimidine-dehydrogenase insufficiency for fluoropyrimidines.

Rapid loss of bone mass and strength in mice after abdominal irradiation

Localized irradiation is a common treatment modality for malignancies in the pelvic-abdominal cavity. We report here on the changes in bone mass and strength in mice 7-14 days after abdominal irradiation. Male C57BL/6 mice of 10-12 weeks of age were given a single-dose (0, 5, 10, 15 or 20 Gy) or fractionated (3 Gy × 2 per day × 7.5 days) X rays to the abdomen and monitored daily for up to 14 days. A decrease in the serum bone formation marker and ex vivo osteoblast differentiation was detected 7 days after a single dose of radiation, with little change in the serum bone resorption marker and ex vivo osteoclast formation. A single dose of radiation elicited a loss of bone mineral density (BMD) within 14 days of irradiation. The BMD loss was up to 4.1% in the whole skeleton, 7.3% in tibia, and 7.7% in the femur. Fractionated abdominal irradiation induced similar extents of BMD loss 10 days after the last fraction: 6.2% in the whole skeleton, 5.1% in tibia, and 13.8% in the femur. The loss of BMD was dependent on radiation dose and was more profound in the trabecula-rich regions of the long bones. Moreover, BMD loss in the total skeleton and the femurs progressed with time. Peak load and stiffness in the mid-shaft tibia from irradiated mice were 11.2-14.2% and 11.5-25.0% lower, respectively, than sham controls tested 7 days after a single-dose abdominal irradiation. Our data demonstrate that abdominal irradiation induces a rapid loss of BMD in the mouse skeleton. These effects are bone type- and region-specific but are independent of radiation fractionation. The radiation-induced abscopal damage to the skeleton is manifested by the deterioration of biomechanical properties of the affected bone.

Orally administered emu oil decreases acute inflammation and alters selected small intestinal parameters in a rat model of mucositis

Mucositis resulting from cancer chemotherapy is a serious disorder of the alimentary tract. Emu oil has demonstrated anti-inflammatory properties in animal models of arthritis and wound healing; however, its effects on the intestine remain unknown. We investigated emu oil for its potential to decrease the severity of mucositis in a rat model. Female Dark Agouti rats (110-150 g) were orogastrically gavaged with emu oil (0.5 or 1 ml) or water (1 ml) for 5 d before intraperitoneal injection of 5-fluorouracil (5-FU, 150 mg/kg) or saline (control), and this was continued up to the day of sacrifice (48, 72 and 96 h post 5-FU administration). Histological (villus height, crypt depth (CD) and disease severity score) and biochemical (myeloperoxidase (MPO) activity) parameters were determined in intestinal tissues collected at sacrifice. Sucrase activity in vivo was quantified by the sucrose breath test. Activated neutrophil activity (MPO) in the ileum was significantly decreased by emu oil (0.5 ml, 451 (sem 168) U/g and 1 ml, 503 (sem 213) U/g) compared with 5-FU-treated controls (1724 (sem 431) U/g) 96 h post 5-FU administration. There were also significant increases in CD (152 (sem 8) microm) in the ileum of rats that received 1 ml emu oil at 96 h compared with 5-FU-treated controls (CD (106 (sem 12) microm)). Emu oil did not affect sucrase activity. Emu oil decreased acute ileal inflammation, and improved mucosal architecture in the intestine during recovery from chemotherapy in rats. Further studies investigating the potential benefits of emu oil as a nutritional supplement for the treatment of intestinal disorders are indicated.

Prevention and mitigation of acute death of mice after abdominal irradiation by the antioxidant N-acetyl-cysteine (NAC)

Gastrointestinal (GI) injury is a major cause of acute death after total-body exposure to large doses of ionizing radiation, but the cellular and molecular explanations for GI death remain dubious. To address this issue, we developed a murine abdominal irradiation model. Mice were irradiated with a single dose of X rays to the abdomen, treated with daily s.c. injection of N-acetyl-l-cysteine (NAC) or vehicle for 7 days starting either 4 h before or 2 h after irradiation, and monitored for up to 30 days. Separately, mice from each group were assayed 6 days after irradiation for bone marrow reactive oxygen species (ROS), ex vivo colony formation of bone marrow stromal cells, and histological changes in the duodenum. Irradiation of the abdomen caused dose-dependent weight loss and mortality. Radiation-induced acute death was preceded not only by a massive loss of duodenal villi but also, surprisingly, abscopal suppression of stromal cells and elevation of ROS in the nonirradiated bone marrow. NAC diminished these radiation-induced changes and improved 10- and 30-day survival rates to >50% compared with <5% in vehicle-treated controls. Our data establish a central role for abscopal stimulation of bone marrow ROS in acute death in mice after abdominal irradiation.

Pro-inflammatory cytokines play a key role in the development of radiotherapy-induced gastrointestinal mucositis

Background

Mucositis is a toxic side effect of anti-cancer treatments and is a major focus in cancer research. Pro-inflammatory cytokines have previously been implicated in the pathophysiology of chemotherapy-induced gastrointestinal mucositis. However, whether they play a key role in the development of radiotherapy-induced gastrointestinal mucositis is still unknown. Therefore, the aim of the present study was to characterise the expression of pro-inflammatory cytokines in the gastrointestinal tract using a rat model of fractionated radiotherapy-induced toxicity.

Methods

Thirty six female Dark Agouti rats were randomly assigned into groups and received 2.5 Gys abdominal radiotherapy three times a week over six weeks. Real time PCR was conducted to determine the relative change in mRNA expression of pro-inflammatory cytokines IL-1β, IL-6 and TNF in the jejunum and colon. Protein expression of IL-1β, IL-6 and TNF in the intestinal epithelium was investigated using qualitative immunohistochemistry.

Results

Radiotherapy-induced sub-acute damage was associated with significantly upregulated IL-1β, IL-6 and TNF mRNA levels in the jejunum and colon. The majority of pro-inflammatory cytokine protein expression in the jejunum and colon exhibited minimal change following fractionated radiotherapy.

Conclusions

Pro-inflammatory cytokines play a key role in radiotherapy-induced gastrointestinal mucositis in the sub-acute onset setting.

The experience of a sore mouth and associated symptoms in patients with cancer receiving outpatient chemotherapy

This study aimed to describe sore mouth (SM) severity and distress, associated symptoms, and consequences in cancer chemotherapy outpatients. Secondary analysis was used in this study. A total of 223 patients in 4 treatment centers participated in the study. Data from an intervention study using a computer-based telephone communication system to assess patients' daily symptom experience were analyzed to obtain highest, average, and lowest ratings of severity and distress for SM, fatigue, trouble sleeping, feeling down/blue, and feeling anxious. Consequence data included oral intake, time spent lying down, ability to work, and daily activity. Approximately 51% reported SM, with a mean highest, average, and lowest severity score of 3.1 in cycle 2 and 3.09 in cycle 3. Sore mouth severity was correlated with severity of fatigue, feeling down/blue, feeling anxious, and trouble sleeping. Sore mouth distress was correlated with the same symptoms. Sore mouth severity was correlated with the number of 8-oz glasses of liquid consumed, effect on daily activity, time spent lying down, but not with ability to work. Half of patients experienced SM, which was associated with several other symptoms and led to specific consequences. Understanding the complex symptom experience of patients with SM, including consequences, will assist nurses in developing more comprehensive clinical assessments and interventions. In addition, the association of multiple symptoms with SM will provide a foundation for further research investigation in oral mucositis.

Methotrexate induces intestinal mucositis and alters gut protein metabolism independently of reduced food intake

One of the main secondary toxic side effects of antimitotic agents used to treat cancer patients is intestinal mucositis. This one is characterized by compromised digestive and absorptive functions, barrier integrity, and immune competence. At the same time, food intake is decreased, which may induce intestinal damages per se. The aim of the study was to characterize which alterations are specific to methotrexate, independently of the anorexic effect of the drug. Male Sprague-Dawley rats received subcutaneously saline solution as control group or 2.5 mg/kg of methotrexate during 3 days (D0-D2). Methotrexate-treated rats were compared with ad libitum and pair-fed controls. Histological examinations and specific markers of the immune and nonimmune gut barrier function were assessed at D4 or D7. Compared with ad libitum and pair-fed controls, methotrexate induced at D4 villus atrophy associated with epithelial necrosis. Mucosal protein synthesis rate and mucin contents of methotrexate treated rats were reduced. At the same time, cathepsin D proteolytic activity was increased compared with ad libitum and pair-fed controls, whereas calpain activity was increased when compared with the only pair-fed controls. These intestinal lesions were associated with various metabolic disturbances such as increased TNF-alpha level and inflammation score in the jejunum but also disturbances of amino acid concentrations in the duodenum and plasma. At D7, these alterations were partially or completely normalized. In addition to the consequences of a low food intake, methotrexate further impairs different biological processes leading to a dramatic loss of gut homeostasis. Targeted nutritional management of chemotherapy receiving patients should be set up to prevent or limit such alterations.

Emerging drugs for chemotherapy-induced mucositis

BACKGROUND

Chemotherapy-induced mucositis is an increasingly recognized problem in cancer management, preventing full doses of treatment being given, compromising cure rates and reducing quality of life. Symptoms include mouth pain and ulceration, esophagitis, abdominal pain, bloating, and diarrhea. It is associated with increased infections and occasional mortality, and its palliation is very expensive. The pathobiology of mucositis is complex, and agents that target mechanisms to prevent mucositis or accelerate healing are in high demand.

OBJECTIVES

To review existing and potential treatments for chemotherapy-induced mucositis in the context of current knowledge of pathobiology.

METHODS

We searched for mucositis of any region of the gastrointestinal tract using Medline, the Pharmaprojects database and listed patents.

RESULTS/CONCLUSIONS

There are many agents in varying stages of development for chemotherapy-induced mucositis. The field is complicated by the question of whether treatments should be developed as drugs or as medical foods, and whether the burden of proof of efficacy and safety should be different.

New pathways for alimentary mucositis

Alimentary mucositis is a major dose-limiting toxicity associated with anticancer treatment. It is responsible for reducing patient quality of life and represents a significant economic burden in oncology. The pathobiology of alimentary mucositis is extremely complex, and an increased understanding of mechanisms and pathway interactions is required to rationally design improved therapies. This review describes the latest advances in defining mechanisms of alimentary mucositis pathobiology in the context of pathway activation. It focuses particularly on the recent genome-wide analyses of regimen-related mucosal injury and the identification of specific regulatory pathways implicated in mucositis development. This review also discusses the currently known alimentary mucositis risk factors and the development of novel treatments. Suggestions for future research directions have been raised.

Technological advances in mucositis research: new insights and new issues

The last decade has seen a significant acceleration in the introduction of molecular tools used in cancer diagnosis and treatment. Driving factors have been the movement of advanced technologies from the laboratory to the clinic and the shift to a more genetically individualised patient approach. With this has followed an increased ability to study the toxic side effects of cancer treatment, some of which are newly emerging, by utilising many of the same technologies. Mucositis research in particular has reached a golden period of investigation and understanding of the pathobiological mechanisms that contribute to the development of the condition. This paper has selected a few of the emerging technologies that are highly relevant to mucositis research to discuss in detail. These technologies include target therapies, toxicogenomics, nanomedicine, pharmacogenetics and pharmacogenomics, with a particular focus on microarray technology. These technologies are critical to discuss in the context of mucositis research not only because they are widely applicable to cutting edge research, but they also provide opportunities for further advances both in the laboratory and clinical setting. In addition, some of these technologies have the potential to be implemented immediately in the field of mucositis research.

Gene expression analysis of multiple gastrointestinal regions reveals activation of common cell regulatory pathways following cytotoxic chemotherapy

Gastrointestinal mucositis involves many changes at the gene level, affecting epithelial/subepithelial interactions and leading to overt damage. The regional specificity and time course of these changes, and how they relate to subsequent mucositis development however remain unknown. The aim of this study was to determine the early time course of gene expression changes along the gastrointestinal tract of the DA rat following chemotherapy. Female DA rats were treated with a single dose of 200 mg/kg irinotecan to induce mucositis, and were killed at short intervals following treatment. Small sections of stomach, jejunum and colon were harvested for analysis of genetic profiles. RNA was hybridised to high density Affymetrix oligonucleotide microarrays. Data analysis was carried out with software package, TimeCourse, freely available through Bioconductor. As early as 1 hr following chemotherapy, expression of hundreds of genes was altered, including those for transcription factors, stress response proteins and protein turnover. These genes are involved in cell proliferation, differentiation and apoptosis along with other cellular processes. At early time points, there was a significant response involving the mitogen-activated protein kinase pathway, cell cycle regulation and cytokine receptor signalling. At later time points, changes to the complement cascade became prominent. We have shown that changes in gene expression following chemotherapy occur by 1 hr, and persist for at least 72 hr after treatment. Many of these changes are highly likely to be specifically related to the subsequent development of gastrointestinal mucositis.

A novel animal model to investigate fractionated radiotherapy-induced alimentary mucositis: the role of apoptosis, p53, nuclear factor-kappaB, COX-1, and COX-2

Radiation-induced mucositis is a common and serious side effect of radiotherapy. Molecular mechanisms of mucosal injury, however, are still poorly understood and extremely difficult to study in humans. A novel Dark Agouti rat model using fractionated radiotherapy to induce mucositis has been developed to investigate the occurrence of alimentary mucosal injury. Twenty-four Dark Agouti rats were randomly assigned to receive either fractionated radiotherapy or no radiotherapy. The irradiated rats received a fractionated course of abdominal radiotherapy at 45 Gy/18 fractions/6 weeks treating thrice weekly (i.e., at a radiation dose of 2.5 Gy per fraction). After each week of radiation, a group of irradiated rats was killed. Histomorphology and mucin distribution in the alimentary tract was investigated. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to examine apoptosis in the colon and jejunum, and intestinal morphometry was used to assess villus length, crypt length, and mitotic crypt count. Immunohistochemistry of p53, nuclear factor-kappaB, cyclooxygenase (COX)-1, and COX-2 was also done. The fractionated radiotherapy course induced alimentary mucositis from week 1, with more severe injury seen in the small intestine. The hallmark appearance of apoptosis was present in the crypts of the small and large intestine. In the jejunum and colon, goblet cell disorganization and degeneration was obvious and crypt mitotic counts were severely depleted throughout the treatment. Expression of p53, nuclear factor-kappaB, COX-1, and COX-2 was increased in the irradiated intestinal sections. Fractionated radiation-induced alimentary mucositis has been effectively documented in the Dark Agouti rat for the first time. Further studies investigating the molecular mechanisms underlying radiation-induced mucositis are planned to ultimately achieve anti-mucotoxic-targeted therapies.

Intestinal toxicity induced by 5-fluorouracil in pigs: a new preclinical model

BACKGROUND

The goal of this study was to develop an animal model of intestinal injury induced by 5-fluorouracil (5-FU) in pigs.

METHODS

Six domestic pigs were used as control (healthy group) and another 6 malnourished pigs orally received 5-FU (treated group). After 4 weeks of treatment, pigs were sacrificed and jejunum, ileum and colon were isolated for histological, immunological and biochemical analyses.

RESULTS

5-FU caused a decrease in the intestinal mass. Disaccharidase, and phosphate alkaline activities, and glutathione redox cycle were disrupted by 5-FU. Histopathological alterations in the crypts and villous were greater in the small intestine than in the colon. 5-FU decreased the number of peripheral and intestinal leukocytes, promoting an increase in T-cytotoxic cells and a decrease in T-helper and B cells.

CONCLUSION

This pig model of intestinal dysfunction closely mimics the common side effects of cancer chemotherapy in humans, and provides a useful tool for evaluating novel antimucotoxic agents.

Establishment of a single-dose irinotecan model of gastrointestinal mucositis

BACKGROUND

Irinotecan is a common cytotoxic agent used in advanced colorectal cancers. However, a major clinical problem with this cytotoxic is that it causes gastrointestinal mucositis manifest by severe diarrhoea. To date there is no established single dose of irinotecan in rats to enable determination of changes occurring following administration. Therefore, the primary aim of this study was to determine a single dose of irinotecan that induced reproducible gastrointestinal mucositis in DA rats. The secondary aim was to determine if the presence of tumour altered the development of mucositis.

METHODS

Eighty-eight rats were divided into two groups, 44 received tumours and 44 remained tumour naïve. These were randomized to receive a single dose of irinotecan at 150, 200, 250 or 300 mg/kg. Two control groups of rats received either no treatment or 2 doses of 150 mg/kg irinotecan, shown previously to induce reproducible gastrointestinal mucositis. Rats were monitored closely for incidence and severity of diarrhoea, and mortality, before being killed 48 and 144 h following treatment.

RESULTS

Rats administered 250 and 300 mg/kg of irinotecan all developed diarrhoea, and this was associated with high mortality rates (up to 100%). Necropsies revealed that many of these rats had duodenal perforations and fatty lysis consistent with peritonitis. The lower doses of 150 and 200 mg/kg irinotecan also caused diarrhoea, but were not associated with high mortality rates. Histopathological examination confirmed small and large intestinal damage in all rats that received irinotecan, regardless of dose. Tumour-bearing rats had worse diarrhoea and higher mortality compared to tumour-naïve rats.

CONCLUSIONS

We find that a single dose of 200 mg/kg irinotecan causes reproducible gastrointestinal mucositis as measured by levels of diarrhoea, and small and large intestinal histology. Importantly this dose has a low mortality. The response to irinotecan is more pronounced in tumour-bearing rats.

Characterisation of mucosal changes in the alimentary tract following administration of irinotecan: implications for the pathobiology of mucositis

PURPOSE

The pathobiology of alimentary tract (AT) mucositis is complex and there is limited information about the events which lead to the mucosal damage that occurs during cancer treatment. Various transcription factors and proinflammatory cytokines are thought to play important roles in pathogenesis of mucositis. The aim of this study was to determine the expression of nuclear factor-kappaB (NF-kappaB), tumor necrosis factor (TNF) and interleukins-1beta (IL-1beta) and -6 (IL-6) in the AT following the administration of the chemotherapeutic agent irinotecan.

METHODS

Eighty-one female dark Agouti rats were assigned to either control or experimental groups according to a specific time point. Following administration of irinotecan, rats were monitored for the development of diarrhoea. The rats were killed at times ranging from 30 min to 72 h after administration of irinotecan. Oral mucosa, jejunum and colon were collected and standard immunohistochemical techniques were used to identify NF-kappaB, TNF, IL-1beta and IL-6 within the tissues. Sections were also stained with haematoxylin and eosin for histological examination.

RESULTS

Irinotecan caused mild to moderate diarrhoea in a proportion of the rats that received the drug. Altered histological features of all tissues from rats administered irinotecan were observed which included epithelial atrophy in the oral mucosa, reduction of villus height and crypt length in the jejunum and a reduction in crypt length in the colon. Tissue staining for NF-kappaB, TNF and IL-1beta and IL-6 peaked at between 2 and 12 h in the tissues examined.

CONCLUSIONS

This is the first study to demonstrate histological and immunohistochemical evidence of changes occurring concurrently in different sites of the AT following chemotherapy. The results of the study provide further evidence for the role of NF-kappaB and associated pro-inflammatory cytokines in the pathobiology of AT mucositis. The presence of these factors in tissues from different sites of the AT also suggests that there may be a common pathway along the entire AT causing mucositis following irinotecan administration.

The role of pro-inflammatory cytokines in cancer treatment-induced alimentary tract mucositis: pathobiology, animal models and cytotoxic drugs

Alimentary tract (AT) mucositis can be a major problem for patients undergoing cancer treatment. It has significant clinical and economic consequences and is a major factor that can compromise the provision of optimal treatment for patients. The pathobiology of AT mucositis is complex and the exact mechanisms that underlie its development still need to be fully elucidated. Current opinion considers that there is a prominent interplay between all of the compartments of the mucosa involving, at a molecular level, the activation of transcription factors, particularly nuclear factor-kappaB, and the subsequent upregulation of pro-inflammatory cytokines and inflammatory mediators. The purpose of this review is to examine the literature relating to what is currently known about the pathobiology of AT mucositis, particularly with respect to the involvement of pro-inflammatory cytokines, as well as currently used animal models and the role of specific cytotoxic chemotherapy agents in the development of AT mucositis.

Role of p53 in irinotecan-induced intestinal cell death and mucosal damage

Irinotecan treatment of colorectal cancers results in high-grade intestinal mucositis in a large proportion of patients. The mechanisms behind irinotecan-induced mucosal injury, however, have yet to be fully explained. The aim of this study was to investigate the role of the p53 protein in the onset of intestinal damage following irinotecan treatment in two different settings. IEC-6 and FHs 74 intestinal cell lines were treated with irinotecan with and without a temporary p53 inhibitor, pifithrin-alpha, and examined for changes in proliferation and survival along with expression of p53 and related proteins. Forty tumour-bearing rats also underwent irinotecan treatment with and without pifithrin-alpha, and the effects on intestinal morphology, gene expression, apoptosis and other toxicities were assessed. Irinotecan caused a dose-dependent reduction in cell viability that was not prevented by pifithrin-alpha in either cell line. Rats responded to irinotecan with diarrhoea, weight loss, histopathological changes to the small and large intestine, increased crypt apoptosis, and a mild inflammatory response. Pifithrin-alpha reduced severity and duration of intestinal apoptosis; however, it did not significantly affect other parameters including p53 expression. Temporary inhibition of p53 activation does not markedly prevent intestinal cell death or mucositis following irinotecan treatment. Irinotecan may act through upregulation of proapoptotic proteins Bax and Bak to induce cell death.

Assessing and Managing Chemotherapy-Induced Mucositis Pain

Acute pain is the major clinical problem associated with mucositis. Mucosal tissue injury is a dose-limiting toxicity of many cancer therapies. Because the number of patients treated with combinations of high-dose chemotherapy agents is likely to increase, more patients are at risk for mucositis. Currently, no consensus exists regarding mucositis prevention, assessment, or treatment. Similarly, research is needed in methods to accurately assess and manage pain for mucositis. Multiple interventional approaches are needed to decrease the emotional and physical distress caused by acute oral pain and mucositis. An assessment tool that includes physical, functional, and pain parameters is presented. Although approaches to prevent and treat mucositis are increasing, appropriate assessment and timely directed interventions can minimize patient distress.

Radiation therapy-induced mucositis: Relationships between fractionated radiation, NF-κB, COX-1, and COX-2

Radiation therapy is one of the three major treatment modalities used in eradicating malignant tumours. When ionising radiation is used to treat abdominal tumours, severe side effects largely due to mucosal damage in the alimentary tract are common, particularly when it is combined with chemotherapy. Radiation-induced mucositis may not only limit the therapeutic doses of combined treatment but also adversely affect the quality of life of the patient. Treatment strategies to treat and prevent radiation-induced mucositis have been reviewed and published in the Clinical Practice Guidelines, 2004. However evidence supporting an effective treatment approach is tenuous, probably because the mechanistic evolution of radiation-induced mucositis is poorly understood. Several animal models have been used to examine the various effects of radiation but no single animal model has been able to effectively capture the effects of radiation on the alimentary tract at the molecular level before symptoms begin. This review will outline the events which occur following radiation exposure; from chromosomal aberrations in the mucosal cells leading to apoptotic and mitotic death, to the evolution of mucositis involving changes in gene activations and signaling. A better understanding of the mechanisms of radiation therapy-induced mucositis is necessary as it will allow for future pharmaceutical interventions to alleviate if not eliminate the debilitating side effects.

Mucosal injury from targeted anti-cancer therapy

BACKGROUND

With the increased use of so-called targeted anti-cancer therapies, there has been a change in toxicities that patients are experiencing. As most targeted therapies are given in conjunction with more traditional chemotherapeutic agents, toxicities of these combination therapies are also evolving. Whilst we increasingly understand the mechanisms underlying the toxicities of chemotherapy and radiotherapy, the addition of targeted treatments requires a new understanding of both toxicity and interacting mechanisms.

AIMS

The aims of this review (which formed the basis of an invited plenary lecture at the 2006 Annual conference of the Multinational Association of Supportive Care in Cancer) were to define targeted anti-cancer therapy, to describe its known impact on the mucosa, either alone, or in combination with chemotherapy with or without radiotherapy, and finally to provide an outline for future directions in research into mucosal injury from targeted anti-cancer therapies.

METHODOLOGY

Two separate literature reviews were conducted. The combined reviews produced 700 papers of which approximately 70 were included in the review.

RESULTS

As with mucosal injury (or mucositis) in general, the studies are hampered by a lack of mucosal injury as primary endpoint, and the variable definitions and levels of reporting. The depth to which mucosal injury was studied was also inadequate. However, it is clear that the key to understanding toxicity is to understand the mechanism of action of the drug, from which it should be possible to predict the toxicities that will occur.

CONCLUSIONS

With the increasing use of targeted anti-cancer therapies, mucosal injury, particularly in its manifestations of diarrhoea, and mouth ulcers, is becoming even more prominent. More publications of basic and clinical research in this area is required.

Palifermin (recombinant keratinocyte growth factor-1): a pleiotropic growth factor with multiple biological activities in preventing chemotherapy- and radiotherapy-induced mucositis

Oral and intestinal mucositis are among the most significant dose-limiting toxic effects of intensive cancer treatment and are associated with adverse clinical and economic outcomes. Palifermin (Kepivancetrade mark), an N-truncated recombinant human keratinocyte growth factor-1, is the first agent to be approved for prevention of oral mucositis. Keratinocyte growth factor, a potent epithelial mitogen, appears to play a major role in the healing process. Palifermin has multiple biological activities that appear to protect the mucosal epithelium and promote its early regeneration after irradiation- and chemotherapy-induced injury. These include inhibition of epithelial cell apoptosis and DNA damage, up-regulation of detoxifying enzymes and down-regulation of pro-inflammatory cytokines, as well as enhanced migration, proliferation and differentiation of epithelial cells. Palifermin reduces the incidence, severity and duration of oral mucositis in patients with haematological malignancies undergoing myelotoxic conditioning therapy and haematopoietic stem-cell transplantation. Clinical sequelae, including febrile neutropenia and resource use (opioid analgesia and parenteral feeding), are concomitantly reduced. Other potential applications being explored include use in the solid tumour setting, reduction of intestinal mucositis and reduction of GVHD in allogenic transplantation. Thus, the development of palifermin and other potential new agents for preventing chemotherapy- and radiotherapy-induced mucositis represents an important breakthrough in oncological supportive care.

Nuclear factor-kappaB (NF-kappaB) and cyclooxygenase-2 (COX-2) expression in the oral mucosa following cancer chemotherapy

Oral mucositis is a serious and debilitating side effect of cancer treatment. Greater understanding of the pathobiology of mucositis has recently led to the advent of targeted treatments for specific patient populations; however the treatment for mucositis remains palliative for most patients. Nuclear factor-kappaB (NF-kappaB) and cyclooxygenase 2 (COX-2) are thought to play important roles in the development of mucositis. In this study, 20 patients undergoing cytotoxic chemotherapy had oral mucosal biopsies taken prior to and following administration of cytotoxic chemotherapy. The samples were stained for NF-kappaB and COX-2 using routine immunohistochemistry. The results from this preliminary study demonstrated statistically significant increased oral mucosal staining for NF-kappaB and COX-2 following cytotoxic chemotherapy and provide further support for the role of NF-kappaB and COX-2 in the pathogenesis of mucositis.

Irinotecan changes gene expression in the small intestine of the rat with breast cancer

PURPOSE

The aetiology of mucositis is complex involving change in gene expression, altered apoptosis and interaction between epithelial and subepithelial compartments. This is the first investigation using microarray to assess chemotherapy-induced changes in the gut. The aims of this study were to identify genes that are altered by irinotecan, to determine how these genes contribute to apoptosis and to identify any potential gene families and pathways that are important for mucositis development.

METHODS

Tumour-bearing female dark Agouti rats were administered twice with 150 mg/kg of irinotecan and killed 6 h after the final dose. Jejunal tissue was harvested and RNA was isolated. cDNA was synthesised and purified, prior to hybridisation and microarray analysis. A 5-K oligo clone set was used to investigate gene expression. Results from the microarray were quantified using RT-PCR.

RESULTS

Many genes were significantly up- or down-regulated by irinotecan. In particular, multiple genes implicated in the mitogen-activated protein kinase (MAPK) signalling pathway were differentially regulated following treatment. These included interleukin 1 receptor, caspases, protein kinase C and dual-specificity phosphatase 6. RT-PCR was used to confirm effects of irinotecan on caspase-1 expression in jejunal tissue and was significantly increased 6 h after treatment with irinotecan.

CONCLUSIONS

This study has identified MAP kinase signalling as being involved with irinotecan-induced intestinal damage and confirms previous findings with radiation-induced oral mucosal damage, which also implicated this pathway. Microarrays are emerging as a valuable tool in mucositis research by linking such findings. The common pathway of chemotherapy- and radiotherapy-induced damage, which utilises the caspase-cascade, may be a useful target to prevent apoptosis following cancer treatment.

Cancer chemotherapy-induced diarrhoea and constipation: mechanisms of damage and prevention strategies

BACKGROUND

Diarrhoea and constipation are common toxicities of chemotherapy, and both are poorly understood. They are manifestations of alimentary mucositis, a condition which affects the entire gastrointestinal tract.

DISCUSSION

The absolute percentage of patients that have diarrhoea or constipation as a result of their treatment has yet to be fully defined, although general estimates place 10% of patients with advanced cancer as being afflicted. Although there has been some major progress in recent years with understanding the mechanisms of oral and small intestinal mucositis, diarrhoea and constipation have received very little attention. Although diarrhoea is a well-recognised side-effect of both chemotherapy and radiotherapy, very little research has been conducted on the mechanisms behind diarrhoea or its treatment. Much of the information in the published literature is based on clinical observations with very little basic science existing. Constipation is not as well recognised and very little is known about its mechanisms.

OBJECTIVES

This review will examine in detail the potentially complex pathogenesis of post-chemotherapy diarrhoea in both animal models and the clinical setting. Furthermore, it will explore what is known about chemotherapy-induced constipation. It will then outline an evidence-based pathway for the investigation and treatment of post-chemotherapy diarrhoea and constipation.

Intestinal mucositis: the role of the Bcl-2 family, p53 and caspases in chemotherapy-induced damage

Intestinal mucositis occurs as a consequence of cytotoxic treatment through multiple mechanisms including induction of crypt cell death (apoptosis) and cytostasis. The molecular control of these actions throughout the gastrointestinal tract has yet to be fully elucidated; however, they are known to involve p53, the Bcl-2 family and caspases. This review will provide an overview of current research as well as identify areas where gaps in knowledge exist.

Nuclear factor kappaB (NFkappaB) and cyclooxygenase-2 (Cox-2) expression in the irradiated colorectum is associated with subsequent histopathological changes

PURPOSE

Recent studies have proposed that mucositis development is the same throughout the gastrointestinal tract (GIT), as it is formed from one structure embryologically. Radiation-induced oral mucositis studies have outlined the key involvement of nuclear factor kappaB (NFkappaB) and cyclooxygenase-2 (Cox-2) in its pathobiology. The purpose of this study was therefore to investigate the expression of NFkappaB and Cox-2 in the irradiated colorectum and to correlate these with the associated histopathologic changes.

METHODS AND MATERIALS

Colorectal tissues from 28 colorectal cancer patients treated with preoperative radiotherapy were analyzed for histopathologic changes using a variety of tissue staining methods. The expression of NFkappaB and Cox-2 in these tissues was investigated using immunohistochemistry. Changes in expression of these proteins were then correlated with the histopathologic changes.

RESULTS

Radiation therapy caused injury to the normal colorectal tissue surrounding tumor site, particularly around the blood vessels. These changes were reflected in changes in NFkappaB and Cox-2 expression.

CONCLUSIONS

We conclude that different regions of the GIT, the colorectum, and oral cavity have similar underlying mechanisms of radiation-induced mucositis. Understanding these mechanisms will allow new approaches to be developed to specifically target steps in the evolution of alimentary mucositis.