Prevention of irinotecan (CPT-11)-induced diarrhea by oral alkalization combined with control of defecation in cancer patients

Mechanisms and emerging strategies for irinotecan-induced diarrhea

Irinotecan (also known as CPT-11) is a topoisomerase I inhibitor first approved for clinical use as an anticancer agent in 1996. Over the past more than two decades, it has been widely used for combination regimens to treat various malignancies, especially in gastrointestinal and lung cancers. However, severe dose-limiting toxicities, especially gastrointestinal toxicity such as late-onset diarrhea, were frequently observed in irinotecan-based therapy, thus largely limiting the clinical application of this agent. Current knowledge regarding the pathogenesis of irinotecan-induced diarrhea is characterized by the complicated metabolism of irinotecan to its active metabolite SN-38 and inactive metabolite SN-38G. A series of enzymes and transporters were involved in these metabolic processes, including UGT1A1 and CYP3A4. Genetic polymorphisms of these metabolizing enzymes were significantly associated with the occurrence of irinotecan-induced diarrhea. Recent discoveries and progress made on the detailed mechanisms enable the identification of potential biomarkers for predicting diarrhea and as such guiding the proper patient selection with a better range of tolerant dosages. In this review, we introduce the metabolic process of irinotecan and describe the pathogenic mechanisms underlying irinotecan-induced diarrhea. Based on the mechanisms, we further outline the potential biomarkers for predicting the severity of diarrhea. Finally, based on the current experimental evidence in preclinical and clinical studies, we discuss and prospect the current and emerging strategies for the prevention of irinotecan-induced diarrhea.

Species differences in small intestinal exposure-related epithelial vacuolation in rats and dogs treated with a heteroaryldihydropyrimidine molecule

Small intestinal epithelial vacuolation induced by a heteroaryldihydropyrimidine compound (HAP-1) was observed in rats but not in dogs at termination in screening toxicity studies, despite the plasma exposure being higher in dogs. To understand the species differences, investigational studies with multiple time points following single dose (SD) and 7-day repeated dose (RD) were conducted in both species at doses resulting in comparable plasma exposures. In rats, epithelial vacuolation in the duodenum and jejunum were observed at all time points. In dogs, transient vacuolation was noted at 8 h post-SD (SD_8h) and 4 h post-RD (RD_4 h), but not at termination (RD_24 h). Special stains demonstrated lipid accumulation within enterocytes in both species and intracytoplasmic inclusion bodies in rats. Transmission electron microscopy identified these inclusion bodies as endoplasmic reticulum (ER) membranous structures. Transcriptomic analysis on jejunal mucosa at SD_8 h and RD_24 h revealed perturbations of lipid metabolism-related genes at SD_8 h in both species, but not at RD_24 h in dogs. ER stress-related gene changes at both time points were observed in rats only. Despite comparable HAP-1 plasma exposures, the duodenum and jejunum tissue concentrations of HAP-1 and acyl glucuronide metabolite were >5- and >30-fold higher in rats than in dogs, respectively. In vitro, similar cytotoxicity was observed in rat and dog duodenal organoids treated with HAP-1. In conclusion, HAP-1-induced intestinal epithelial vacuolation was related to lipid metabolism dysregulation in both species and ER-related injuries in rats only. The species differences were likely related to the difference in intestinal exposure to HAP-1 and its reactive metabolite.

Efficacy of Hangeshashinto in the Prevention of Chemotherapy-Induced Diarrhea: A Systematic Review and Meta-Analysis

Hangeshashinto has attracted attention owing to its potential to prevent chemotherapy-induced diarrhea. However, studies on the efficacy of Hangeshashinto have had conflicting results. Evaluating the efficacy of Hangeshashinto may contribute to reducing the use and adverse events caused by drug therapy for chemotherapy-induced diarrhea. Medical Literature Analysis and Retrieval System Online (MEDLINE), PubMed, Ichushi, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov were searched to retrieve all the relevant studies. Randomized controlled trials (RCTs) comparing the administration of Hangeshashinto with that of other treatments in patients with cancer receiving chemotherapy were included. The primary outcome was severe (grade 3-4) diarrhea assessed using the Common Terminology Criteria for Adverse Events. The secondary outcome was mild (grade 0-2) diarrhea. Out of 324 records identified, three studies were selected for the meta-analysis. Irinotecan was used for chemotherapy in all these studies. Hangeshashinto did not reduce the incidence of severe diarrhea compared with other treatments (risk ratio (RR) 0.40, 95% confidence interval (CI) 0.11-1.41, P = 0.15; low-quality evidence). Moreover, Hangeshashinto did not reduce the incidence of mild diarrhea (RR 1.35, 95% CI 0.87-2.09, P = 0.18; low-quality evidence). However, in the subgroup analysis compared with no treatment, the Hangeshashinto group had a significantly lower incidence of severe diarrhea (RR 0.17, 95% CI 0.03-0.88, P = 0.03; low-quality evidence). At present, insufficient evidence exists to support the claim that Hangeshashinto prevents diarrhea caused by irinotecan-based chemotherapy.

Intestinal Flora in Chemotherapy Resistance of Biliary Pancreatic Cancer

Biliary pancreatic malignancy has an occultic onset, a high degree of malignancy, and a poor prognosis. Most clinical patients miss the opportunity for surgical resection of the tumor. Systemic chemotherapy is still one of the important methods for the treatment of biliary pancreatic malignancies. Many chemotherapy regimens are available, but their efficacy is not satisfactory, and the occurrence of chemotherapy resistance is a major reason leading to poor prognosis. With the advancement of studies on intestinal flora, it has been found that intestinal flora is correlated with and plays an important role in chemotherapy resistance. The application of probiotics and other ways to regulate intestinal flora can improve this problem. This paper aims to review and analyze the research progress of intestinal flora in the chemotherapy resistance of biliary pancreatic malignancies to provide new ideas for treatment.

Clinical review of alkalization therapy in cancer treatment

One of the most unique characteristics of cancer metabolism is activated aerobic glycolysis, which is called the “Warburg effect”, and is a hallmark of cancer. An acidic tumor microenvironment (TME) resulting from activated anaerobic glycolysis is associated with cancer progression, multi-drug resistance, and immune escape. Several in vitro and in vivo studies reported that neutralization of the acidic TME by alkalizing agents, such as bicarbonate, resulted in the suppression of cancer progression and a potential benefit for anti-cancer drug responses. In clinical settings, alkalizing effects were achieved not only by alkalizing agents, but also by a following a particular diet. An epidemiological study demonstrated that more fruits and vegetables and less meat and dairy products are associated with an increase in urine pH, which may reflect the alkalizing effect on the body. However, it remains unclear whether alkaline dietary intervention improves the effects of cancer treatment. Moreover, there are few clinical reports to date regarding cancer treatments being performed on patients together with alkalization therapy. In this review, we investigated whether alkalization therapy, which includes an alkaline diet and/or alkalizing agents, improves cancer treatment.

Drug-Repositioning Approaches Based on Medical and Life Science Databases

Drug repositioning is a drug discovery strategy in which an existing drug is utilized as a therapeutic agent for a different disease. As information regarding the safety, pharmacokinetics, and formulation of existing drugs is already available, the cost and time required for drug development is reduced. Conventional drug repositioning has been dominated by a method involving the search for candidate drugs that act on the target molecules of an organism in a diseased state through basic research. However, recently, information hosted on medical information and life science databases have been used in translational research to bridge the gap between basic research in drug repositioning and clinical application. Here, we review an example of drug repositioning wherein candidate drugs were found and their mechanisms of action against a novel therapeutic target were identified via a basic research method that combines the findings retrieved from various medical and life science databases.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

A randomized controlled, open-label early phase II trial comparing incidence of FOLFIRI.3-induced diarrhoea between Hangeshashinto and oral alkalization in Japanese patients with colorectal cancer

WHAT IS KNOWN AND OBJECTIVE

We conducted a pilot clinical trial to investigate whether Hangeshashinto (TJ-14) could be substituted for oral alkalization in patients scheduled to undergo chemotherapy by FOLFIRI.3 regimen for colorectal cancer (CRC).

METHODS

Patients with CRC were randomized 1:1 to a TJ-14 (7.5 g/day) group or an oral alkalization (sodium bicarbonate, 1.8 g/day; ursodeoxycholic acid, 300 mg/day) group. The primary endpoint was incident of late-onset diarrhoea. A total of 30 patients were randomized to either the TJ-14 group or the alkalization group.

RESULTS AND DISCUSSION

There was no statistical difference in age, concomitantly used drugs or UGT1A1 genotypes between the groups. In the alkalization group (n = 15), the frequency of grade 0/1/2 and grade 3 diarrhoea was 73% and 27%, respectively. In the TJ-14 group (n = 14), the frequency of grade 0/1/2 and grade 3 diarrhoea was 79% and 21%, respectively. Grade 4 diarrhoea was not observed in either group. There was no statistically significant difference in other adverse events or in response to FOLFIRI.3 between the groups.

WHAT IS NEW AND CONCLUSION

This pilot trial suggests that TJ-14 is a promising alternative treatment option to reduce FOLFIRI.3-induced late-onset diarrhoea, although additional clinical study with a larger number of patients is necessary to confirm these results.

Two birds, one stone: hesperetin alleviates chemotherapy-induced diarrhea and potentiates tumor inhibition

Chemotherapy-induced diarrhea (CID), with clinical high incidence, adversely affects the efficacy of cancer treatment and patients' quality of life. Our study demonstrates that the citrus flavonoid hesperetin (Hst) has a superior potential as a new agent to prevent and alleviate CID. In the animal model for irinotecan (CPT-11) induced CID, Hst could selectively inhibit intestinal carboxylesterase (CES2) and thus reduce the local conversion of CPT-11 to cytotoxic SN-38 which causes intestinal toxicity. Oral administration of Hst manifested an excellent anti-diarrhea efficacy, prohibiting 80% of severe and 100% of mild diarrhea in the CPT-11 administered tumor-bearing mice. In addition, a significant attenuation of intestinal inflammation contributed to the anti-diarrhea effect of Hst. Moreover, Hst was found to work synergistically with CPT-11 in tumor inhibition by suppressing the tumor's STAT3 activity and recruiting tumoricidal macrophages into the tumor microenvironment. The anti-intestinal inflammation and anti-STAT3 properties of Hst would contribute its broad benefits to the management of diarrhea caused by other chemo or targeted agents, and more importantly, enhance and reinforce the anti-tumor effects of these agents, to improve patient outcomes.

CPT-11-Induced Delayed Diarrhea Develops via Reduced Aquaporin-3 Expression in the Colon

While irinotecan (CPT-11) has a potent anti-cancer effect, it also causes serious diarrhea as an adverse reaction. In this study, we analyzed the pathogenic mechanism of CPT-11-induced delayed diarrhea by focusing on water channel aquaporin-3 (AQP3) in the colon. When rats received CPT-11, the expression level of AQP3 was reduced during severe diarrhea. It was found that the expression levels of inflammatory cytokines and the loss of crypt cells were increased in the colon when CPT-11 was administered. When celecoxib, an anti-inflammatory drug, was concomitantly administered, both the diarrhea and the reduced expression of AQP3 induced by CPT-11 were suppressed. The inflammation in the rat colon during diarrhea was caused via activated macrophage by CPT-11. These results showed that when CPT-11 is administered, the expression level of AQP3 in the colon is reduced, resulting in delayed diarrhea by preventing water transport from the intestinal tract. It was also suggested that the reduced expression of AQP3 might be due to the inflammation that occurs following the loss of colonic crypt cells and to the damage caused by the direct activation of macrophages by CPT-11. Therefore, it was considered that anti-inflammatory drugs that suppress the reduction of AQP3 expression could prevent CPT-11-induced delayed diarrhea.

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.

A phase II, randomized, double blind trial of calcium aluminosilicate clay versus placebo for the prevention of diarrhea in patients with metastatic colorectal cancer treated with irinotecan

PURPOSE

Calcium aluminosilicate clay (CASAD) is a naturally occurring clay that serves as a cation exchange absorbent. We hypothesized that oral administration of CASAD would reduce the rate of grade 3/4 diarrhea associated with irinotecan use for metastatic colorectal cancer (CRC) by adsorbing the SN-38 metabolite.

METHODS

Patients receiving irinotecan-based chemotherapy were randomized equally between CASAD and placebo arms in this multicenter trial in order to assess differences in the proportions of patients with grade 3/4 diarrhea within 6 weeks. Additionally, we compared symptom severity between the two arms using the M.D. Anderson Symptom Inventory.

RESULTS

Between May 2009 and May 2012, 100 patients were enrolled. In evaluable patients, 7 of 43 (16 %) on the CASAD arm compared to 3 of 32 (9 %) on the placebo arm experienced grade 3/4 diarrhea (P = 0.70). The rate of any diarrhea among all patients was similar (CASAD arm, 64 % vs. placebo arm, 70 %). The rate of study dropout was 14 % in the CASAD arm and 38 % in the placebo arm (P = 0.01). No differences were found in symptom severity, individual symptom items, and in serious adverse events between the two arms.

CONCLUSION

Compared to placebo, CASAD use was safe but ineffective in preventing diarrhea in metastatic CRC patients treated with irinotecan-containing chemotherapy regimens. There were no distinct signals in terms of patient symptoms between arms, but there was significantly more patient dropout in the placebo arm. Future CASAD trials will focus on the active treatment of diarrhea.

Clinical usefulness of testing for UDP glucuronosyltransferase 1 family, polypeptide A1 polymorphism prior to the inititation of irinotecan-based chemotherapy

An association between UDP glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1) polymorphisms and irinotecan-induced neutropenia has been previously reported. In this study, we assessed the clinical usefulness of testing for UGT1A1 polymorphisms prior to the initiation of irinotecan-based chemotherapy, as this remains a controversial subject. A total of 136 lung cancer patients who were treated with a combination of nedaplatin and irinotecan as initial chemotherapy were assessed. Following exclusion of patients exhibiting low UGT1A1 enzyme activity, 70 patients were treated after UGT1A1 polymorphism testing (test group) and 66 patients were treated without UGT1A1 polymorphism testing (non-test group). We retrospectively analyzed and compared the adverse events between the test and the non-test groups and observed no reduction in hematological or non-hematological toxicities in the test group compared to that in the non-test group. Of the 9 patients with grade 4 or 5 non-hematological toxicity, 6 patients had febrile neutropenia (FN). All the patients with FN were aged >70 years. The incidence of adverse events was significantly higher among patients aged >70 years compared to that among younger patients. In conclusion, in patients treated with nedaplatin and irinotecan combination chemotherapy, UGT1A1 polymorphism testing prior to the initiation of chemotherapy did not reduce the incidence of adverse events. Therefore, UGT1A1 polymorphism testing alone may not be sufficient to predict the occurrence of severe adverse events and it may be more important to effectively manage adverse events, particularly in elderly patients.

Old drug new use--amoxapine and its metabolites as potent bacterial β-glucuronidase inhibitors for alleviating cancer drug toxicity

PURPOSE

Irinotecan (CPT-11) induced diarrhea occurs frequently in patients with cancer and limits its usage. Bacteria β-glucuronidase (GUS) enzymes in intestines convert the nontoxic metabolite of CPT-11, SN-38G, to toxic SN-38, and finally lead to damage of intestinal epithelial cells and diarrhea. We previously reported amoxapine as a potent GUS inhibitor in vitro. To further understand the molecular mechanism of amoxapine and its potential for treatment of CPT-11-induced diarrhea, we studied the binding modes of amoxapine and its metabolites by docking and molecular dynamics simulation, and tested the in vivo efficacy on mice in combination with CPT-11.

EXPERIMENTAL DESIGN

The binding of amoxapine, its metabolites, 7-hydroxyamoxapine and 8-hydroxyamoxapine, and a control drug loxapine with GUS was explored by computational protocols. The in vitro potencies of metabolites were measured by Escherichia coli GUS enzyme and cell-based assay. Low-dosage daily oral administration was designed to use along with CPT-11 to treat tumor-bearing mice.

RESULTS

Computational modeling results indicated that amoxapine and its metabolites bound in the active site of GUS and satisfied critical pharmacophore features: aromatic features near bacterial loop residue F365' and hydrogen bond toward E413. Amoxapine and its metabolites were demonstrated as potent in vitro. Administration of low dosages of amoxapine with CPT-11 in mice achieved significant suppression of diarrhea and reduced tumor growth.

CONCLUSIONS

Amoxapine has great clinical potential to be rapidly translated to human subjects for irinotecan-induced diarrhea.

Therapeutic targeting of CPT-11 induced diarrhea: a case for prophylaxis

CPT-11 (irinotecan), a DNA topoisomerase I inhibitor is one of the main treatments for colorectal cancer. The main dose limiting toxicities are neutropenia and late onset diarrhea. Though neutropenia is manageable, CPT-11 induced diarrhea is frequently severe, resulting in hospitalizations, dose reductions or omissions leading to ineffective treatment administration. Many potential agents have been tested in preclinical and clinical studies to prevent or ameliorate CPT-11 induced late onset diarrhea. It is predicted that prophylaxis of CPT-11 induced diarrhea will reduce sub-therapeutic dosing as well as hospitalizations and will eventually lead to dose escalations resulting in better response rates. This article reviews various experimental agents and strategies employed to prevent this debilitating toxicity. Covered topics include schedule/dose modification, intestinal alkalization, structural/chemical modification, genetic testing, anti-diarrheal therapies, transporter (ABCB1, ABCC2, BCRP2) inhibitors, enzyme (β-glucuronidase, UGT1A1, CYP3A4, carboxylesterase, COX-2) inducers and inhibitors, probiotics, antibiotics, adsorbing agents, cytokine and growth factor activators and inhibitors and other miscellaneous agents.

Pharmacokinetic evaluation of the anticancer prodrug simmitecan in different experimental animals

AIM

To investigate the pharmacokinetics and disposition of simmitecan (L-P) that was a water-soluble ester prodrug of chimmitecan (L-2-Z) with potent anti-tumor activities in different experimental animals, and to assess its drug-drug interaction potential.

METHODS

SD rats were injected with a single iv bolus doses of L-P (3.75, 7.5 and 15 mg/kg). The pharmacokinetics, tissue distribution, excretion and metabolism of L-P and its active metabolite L-2-Z were studied through quantitative measurements and metabolite profiling with LC/MS. The binding of L-P and L-2-Z to rat plasma proteins was examined using an ultrafiltration method. Systemic exposures of beagle dogs to L-P as well as drug distribution in tumors of the nude mice xenograft model of human hepatic cancer SMMC-7721 cells were also examined. The metabolism of L-P by liver mcirosomal carboxylesterase in vitro was investigated in different species. The effects of L-P and L-2-Z on cytochrome P450 enzymes were examined using commercial screening kits.

RESULTS

The in vivo biotransformation of L-P to L-2-Z showed a significant species difference, with a mean elimination half-life t1/2 of approximately 1.4 h in rats and 1.9 h in dogs. The systemic exposure levels of L-P and L-2-Z were increased in a dose-dependent manner. In rats, approximately 66% of L-P and 79% of L-2-Z were bound to plasma proteins. In rats and the nude mice bearing human hepatic cancers, most organ tissues had significantly higher concentrations of L-P than the corresponding plasma levels. In the tumor tissues, the L-P levels were comparable to those of plasma, whereas the L-2-Z levels were lower than the L-P levels. In rats, L-P was eliminated mainly via biliary excretion, but metabolism played an important role in elimination of the intact L-P. Finally, L-P and L-2-Z exerted moderate inhibition on the activity of CYP3A4 in vitro.

CONCLUSION

L-P and L-2-Z have relatively short elimination half-lives and L-P is mainly eliminated via biliary excretion. The species difference in the conversion of L-P to L-2-Z and potential drug-drug interactions due to inhibition of CYP3A4 should be considered in further studies.

A randomised double-blind placebo-controlled phase II study of AGI004 for control of chemotherapy-induced diarrhoea

Background:

AGI004 is a controlled-release transdermal patch preparation of mecamylamine. We conducted a randomised placebo-controlled phase II study of two dose levels of AGI004 in chemotherapy-induced diarrhoea (CID).

Methods:

Adult patients receiving chemotherapy who had experienced diarrhoea (NCI grade 1–2) during previous cycles of chemotherapy were eligible. In all, 64 patients were randomised to receive AGI004 4 mg then 8 mg per 24 h transdermal patch or placebo for two sequential cycles of chemotherapy. Patients' severity of diarrhoea was physician-assessed using NCI grade of diarrhoea and patient-assessed using information recorded in daily diaries of bowel movements.

Results:

Overall AGI004 doubled the odds of a response to treatment on the first day of chemotherapy based on physician assessment of NCI grade of diarrhoea compared with placebo (odds ratio=2.0, 90% confidence interval: 0.9–4.5) and there was a trend to improved response rates for AGI004 for the full treatment cycle although these results were not statistically significant. There was also evidence of significantly improved response rates based on patient assessment of diarrhoea both overall (P=0.05) and at the 8-mg dose level (P=0.02) compared with placebo.

Conclusion:

AGI004 demonstrated effectiveness in reducing chemotherapy-associated diarrhoea, with results suggesting response across multiple measurements of diarrhoea. Treatment was well tolerated with no drug-related adverse events. Further evaluation of this agent in the management of CID is warranted.

Phase II study of irinotecan as a third- or fourth-line treatment for advanced non-small cell lung cancer: NJLCG0703

BACKGROUND

We aimed to evaluate the efficacy and safety of irinotecan monotherapy as a third- or fourth-line treatment for advanced non-small cell lung cancer (NSCLC) patients.

METHODS

Patients with advanced NSCLC refractory to 2 or more previous regimens were treated with 80 mg/m2 irinotecan on days 1, 8, and 15, every 4 weeks. The primary endpoint was the overall response rate (ORR), whereas secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity profiles.

RESULTS

From December 2007 to April 2009, 32 patients (median age, 60 years) were enrolled. Most of the patients (75.0%) were male, and 18.8% had a performance status of 2. Six partial responses to irinotecan monotherapy were observed (ORR, 18.8%: 95% confidence interval, 5.3%-32.3%). The disease control rate (DCR) was 78.1%, median PFS was 4.0 months, and median survival time (MST) was 10.4 months. Grade 3-4 neutropenia was observed in 22% of patients, but other toxic effects were moderate. No cases of grade 3-4 diarrhea or treatment-related death were noted. Of the 15 patients for whom progressive disease represented the best response to previous treatment regimens, 2 exhibited a partial response and 9 showed stable disease after irinotecan monotherapy, with a DCR of 73.3%, median PFS of 4.4 months, and MST of 8.2 months.

CONCLUSIONS

Irinotecan monotherapy is effective for advanced NSCLC patients who have previously failed 2 or more treatment regimens.

Drug-induced, factitious, & idiopathic diarrhoea

The aetiology of diarrhoea can often be simple to identify, but in some cases may pose a challenge. The diagnosis of drug-induced diarrhoea can easily be sorted based on timing of the symptom with onset of a new drug. Treatment can vary from simply monitoring and eventual resolution with continuation of the drug, to discontinuation of the offending agent. In cases where a drug cannot always be stopped, additional medications can help control the symptom. Factitious diarrhoea can present a diagnostic challenge if the evaluating physician does not suspect its possibility. Typically a careful history, and in some cases, stool testing can provide clues. The diagnosis of idiopathic diarrhoea is often made when exhaustive testing provides no definite aetiology and the goal of management is supportive care and symptomatic treatment.

Phase II study of irinotecan plus capecitabine in anthracycline- and taxane- pretreated patients with metastatic breast cancer

To evaluate the efficacy and tolerability of combined treatment with irinotecan (I) and capecitabine (X), we conducted a phase II study of the IX combination in anthracycline- and taxane-pretreated patients with metastatic breast cancer (MBC). Patients received 80 mg/m(2) I on days 1 and 8 and 1,000 mg/m(2) X twice daily on days 1-14 of 21-day cycles until disease progression. The primary endpoint was the objective response rate (ORR), and the secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. Thirty-six patients were enrolled between September 2006 and April 2008. The median follow-up was 47.6 months. The ORR was 58.3 % (95 % CI, 42.2-72.9), with 3 complete responses and 18 partial responses. The median PFS was 7.6 months (95 % CI, 5.0-10.2), and the median OS was 20.0 months (95 % CI, 11.6-28.4). Neutropenia was the most common adverse event (grade 3, 30.6 %; grade 4, 27.8 %) with febrile neutropenia in 2 patients (5.6 %). Three patients (8.3 %) had grade 3 diarrhea, 3 patients (8.3 %) had grade 3 asthenia, and 1 patient (2.8 %) had grade 3 hand-foot syndrome. The IX combination was effective and tolerable for anthracycline- and taxane-pretreated patients with MBC. A phase III trial of this combination is ongoing.

Rapid deconjugation of SN-38 glucuronide and adsorption of released free SN-38 by intestinal microorganisms in rat

One of the dose-limiting toxicities of irinotecan hydrochloride (CPT-11) is delayed-onset diarrhea. CPT-11 is converted to its active metabolite, SN-38, which is conjugated to SN-38 glucuronide (SN-38G). SN-38G excreted in the intestinal lumen is extensively deconjugated by bacterial β-glucuronidase, resulting in the regeneration of SN-38, which causes diarrhea. However, the deconjugation of SN-38G by the intestinal microflora remains to be clarified. This study aimed to investigate the microbial transformation of SN-38G by an anaerobic mixed culture of rat cecal microorganisms. Concentrations of SN-38G and SN-38 were then determined using high-performance liquid chromatography. Complete deconjugation of SN-38G to SN-38 in the mixed cultures was observed within 1 h of incubation, with 62.7% of the added SN-38G being found in the supernatant. Approximately 80.4% of the SN-38 in the supernatant was bound to protein, and the remaining 19.6% was detected as active free SN-38. In total, only 12.3% (19.6 × 62.7%) of the SN-38G added to the test tube was found in the supernatant in the ultrafiltrable free form, indicating that approximately 90% of the SN-38G added to the growth medium either remained adsorbed onto the pelleted fraction or occurred in a protein-bound form in the supernatant. The remaining 10% of the SN-38G added to the growth medium existed in the unbound form, the form capable of causing damage to the intestinal membrane. In conclusion, these results indicated that the greater part of the SN-38 produced from SN-38G by the action of bacterial β-glucuronidase is rapidly adsorbed onto intestinal bacterial cell walls or dietary fibers in pelleted fraction, and only 10% remains in the ultrafiltrable unbound form in the intestinal luminal fluid.

Phase I/II study of sequential therapy with irinotecan and S-1 for metastatic colorectal cancer

Background:

Both irinotecan (CPT-11) and S-1 are active against colorectal cancer; however, as S-1 is a prodrug of 5-fluorouracil (5-FU), 5-FU and its metabolites might inhibit the antitumour effect of CPT-11. Therefore, we designed a sequential combination, in which CPT-11 infusion was given on day 1 and S-1 was given orally at 80 mg m⁻² per day on days 3–16 every 3 weeks.

Methods:

Twelve patients entered the phase I study, and the recommended doses were determined as a CPT-11 dose of 150 mg m⁻² and an S-1 dose of 80 mg m⁻².

Results:

In all, 36 patients entered the phase II study, of whom 4 and 16 had complete and partial responses. The overall response rate was 55.6% (95% confidence interval, 38.1–72.1%), and median progression-free survival was 7.7 months (95% confidence interval, 4.8–12.6 months). Grade 3 neutropenia was the most common haematological toxicity and occurred in 6.5% of 215 treatment courses. Grade 3 non-haematological toxicities included anorexia (1.4%) and diarrhoea (0.9%). There was no grade 4 toxicity of any kind.

Conclusion:

Our results suggest that this regimen is convenient, safe and promising, compared with conventional regimens for patients with metastatic colorectal cancer.

Chemotherapy-induced diarrhoea

PURPOSE OF REVIEW

Diarrhoea is a major manifestation of chemotherapy-induced mucositis that until recently has received very little attention. To date, there is no detailed understanding of the underlying mechanisms of the condition. The purpose of this review is to examine the plethora of recent studies, both in the laboratory and in the clinic, which have attempted to elucidate effective treatment options.

RECENT FINDINGS

Over recent years, there have been many new treatment options trialled for ameliorating chemotherapy-induced diarrhoea. Some of these have shown great promise in small clinical studies and now need to be investigated in larger trials. Furthermore, there have been developments in the understanding of the underlying mechanisms of chemotherapy-induced diarrhoea. These developments may also lead to effective treatment options.

SUMMARY

Here, we describe the current thinking behind the mechanisms of chemotherapy-induced diarrhoea and present current and new treatment options. This opinion article highlights the shift towards more effective research into diarrhoea caused by chemotherapy.

Modifications of human carboxylesterase for improved prodrug activation

BACKGROUND

Carboxylesterases (CEs) are ubiquitous enzymes responsible for the hydrolysis of numerous clinically useful drugs. As ester moieties are frequently included in molecules to improve their water solubility and bioavailability, de facto they become substrates for CEs.

OBJECTIVE

In this review, we describe the properties of human CEs with regard to their ability to activate anticancer prodrugs and demonstrate how structure-based design can be used to modulate substrate specificity and to increase efficiency of hydrolysis.

METHODS

A specific example using CPT-11 and a human liver CE is discussed. However, these techniques can be applied to other enzymes and their associated prodrugs.

RESULTS

Structure-guided mutagenesis of CEs can be employed to alter substrate specificity and generate novel enzymes that are efficacious at anticancer prodrug activation.

A phase II trial of modified weekly irinotecan and cisplatin for chemotherapy-naïve patients with metastatic or recurrent squamous cell carcinoma of the esophagus

PURPOSE

This phase II study assessed the efficacy and toxicity profile of a modified weekly irinotecan and cisplatin for chemotherapy-naïve patients with metastatic/recurrent esophageal squamous cell carcinoma (SQCC).

METHODS

The eligibility criteria included histologically confirmed esophageal SQCC, no prior chemotherapy, adequate organ functions and written informed consent. Patients received irinotecan 65 mg/m(2) plus cisplatin 30 mg/m(2) on days 1 and 8, every 3 weeks.

RESULTS

Thirty-two patients were assessed for response and toxicity. Ten patients achieved a partial response (31.3%; 95% CI, 16.0-50.0%). With a median follow-up of 19.0 months, median progression-free and overall survival was 4.4 and 9.6 months, respectively, with a 1-year survival rate of 27.4%. Grade (G) 3/4 neutropenia was observed in 50.0% of the patients, which was the most common cause of dose reduction or therapy delay. G3 non-hematologic toxicity included seven (21.9%) asthenias, four (12.5%) diarrheas, and one (3.1%) nausea/vomiting, but no G4 non-hematologic toxicity was observed.

CONCLUSIONS

This modified weekly irinotecan and cisplatin failed to ameliorate hematologic toxicity and to improve efficacy. However, easy administration and favorable non-hematologic toxicity as well as modest anti-tumor activity against metastatic or recurrent esophageal SQCC can make this regimen a potential treatment option, given the complexity of administration and toxicity of conventional infusional 5-FU and cisplatin.

Camptothecin and podophyllotoxin derivatives: inhibitors of topoisomerase I and II - mechanisms of action, pharmacokinetics and toxicity profile

Camptothecins represent an established class of effective agents that selectively target topoisomerase I by trapping the catalytic intermediate of the topoisomerase I-DNA reaction, the cleavage complex. The water-soluble salt camptothecin-sodium - introduced in early trials in the 1960s - was highly toxic in animals, whereas the semisynthetic derivatives irinotecan and topotecan did not cause haemorrhagic cystitis because of their higher physicochemical stability and solubility at lower pH values. Myelosuppression, neutropenia and, to a lesser extent, thrombocytopenia are dose-limiting toxic effects of topotecan. In contrast to the structurally-related topotecan, irinotecan is a prodrug which has to be converted to SN-38, its active form. SN-38 is inactivated by conjugation, thus patients with Gilbert's syndrome and other forms of genetic glucuronidation deficiency are at an increased risk of irinotecan-induced adverse effects, such as neutropenia and diarrhoea. The cytotoxic mechanism of podophyllotoxin is the inhibition of topoisomerase II. Common adverse effects of etoposide include dose-limiting myelosuppression. Hypersensitivity reactions are more common with etoposide and teniposide than with etoposide phosphate because the formulations of the former contain sensitising solubilisers. Leukopenia and thrombocytopenia occur in 65% and 80%, respectively, of patients after administration of conventional doses of teniposide. Anorexia, vomiting and diarrhoea are generally of mild severity after administration of conventional doses of topoisomerase II inhibitors. Clinical pharmacokinetic studies have revealed substantial interindividual variabilities regarding the area under the concentration-time curve values and steady-state concentrations for all drugs reviewed in this article. Irinotecan, etoposide and teniposide are degraded via complex metabolic pathways. In contrast, topotecan primarily undergoes renal excretion. Regarding etoposide and teniposide, the extent of catechol formation over time during drug metabolism may be associated with a higher risk for secondary malignancies.

Intestinal tract injury by drugs: Importance of metabolite delivery by yellow bile road

Drug secretion into bile is typically considered a safe route of clearance. However, biliary delivery of some drugs or their reactive metabolites to the intestinal tract evokes adverse consequences due to direct toxic actions or indirect disruption of intestinal homeostasis. Biliary concentration of the chemotherapy agent 5-fluorodeoxyuridine (FUDR) and other compounds is associated with bile duct damage while enterohepatic cycling of antibiotics contributes to the disruptions of gut flora that produce diarrhea. The goal of this review is to describe key evidence that biliary delivery is an important factor in the intestinal injury caused by representative drugs. Emphasis will be given to 3 widely used drugs whose reactive metabolites are plausible causes of small intestinal injury, namely the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, the immunosuppressant mycophenolic acid (MPA), and the chemotherapy agent irinotecan. Capsule endoscopy and other sensitive diagnostic techniques have documented a previously unappreciated, high prevalence of small intestinal injury among NSAID users. Clinical use of MPA and irinotecan is frequently associated such severe intestinal injury that dosage must be reduced. Observations from clinical and experimental studies have defined key events in the pathogenesis of these drugs, including roles for multidrug resistance-associated protein 2 (MRP2) and other transporters in biliary secretion and adduction of enterocyte proteins by reactive acyl glucuronide metabolites as a likely mechanism for intestinal injury. New strategies for minimizing the adverse intestinal consequences of irinotecan chemotherapy illustrate how basic information about key events in the biliary secretion of drugs and the nature of their proximate toxicants can lead to safer protocols for drugs.

Prophylaxis of irinotecan-induced diarrhea with neomycin and potential role for UGT1A1*28 genotype screening: a double-blind, randomized, placebo-controlled study

OBJECTIVE

Delayed-type diarrhea is a common side effect of irinotecan and is associated with a bacterial-mediated formation of the active irinotecan metabolite SN-38 from its glucuronide conjugate in the intestine. Based on a pilot study, we hypothesized that concomitant administration of the antibiotic neomycin would diminish exposure of the gut to SN-38 and ameliorate the incidence and severity of diarrhea.

PATIENTS AND METHODS

Patients were treated with irinotecan in a multicenter, double-blind, randomized, placebo-controlled trial. Eligible patients received irinotecan (350 mg/m(2) once every 3 weeks) combined with neomycin (660 mg three times daily for three consecutive days, starting 2 days before chemotherapy) or combined with placebo. Blood samples were obtained for additional pharmacokinetic and pharmacogenetic analyses.

RESULTS

Sixty-two patients were evaluable for the toxicity analysis. Baseline patient characteristics, systemic SN-38 exposure, and UGT1A1*28 genotype status (i.e., an additional TA repeat in the promoter region of uridine diphosphate-glucuronosyltransferase isoform 1A1) were similar in both arms. Although distribution, severity, and duration of delayed-type diarrhea did not differ significantly between arms, grade 3 diarrhea tended to be less frequent in the neomycin arm. The presence of at least one UGT1A1*28 allele was strongly related to the incidence of grade 2-3 diarrhea. In the neomycin arm, grade 2 nausea was significantly more common.

CONCLUSION

Our results do not suggest a major role for neomycin as prophylaxis for irinotecan-induced delayed-type diarrhea. It is suggested that the UGT1A1*28 genotype status could be used as a screening tool for a priori prevention of irinotecan-induced delayed-type diarrhea.

[Pharmacokinetic study of cancer chemotherapy]

We reported that the rate of conversion of lactone to carboxylate forms of irinotecan (CPT-11) and its metabolites plays a major role in the biliary excretion of these compounds. Sulfobromophthalein partially inhibited the secretion of SN-38-glucronide into the gastrointestinal lumen, whereas little change was seen in that of active metabolite SN-38. Co-administration of sulphobromophthalein with CPT-11 might lower the late-onset gastrointestinal toxicity observed during treatment with CPT-11 without lowering anticancer activity. In the ileum, the level of transport in the direction form the serosal layer to mucosal layer was significantly greater than that in the direction form the mucosal layer to serosal layer, whereas a significant difference was not observed in the jejunum. This secretory transport required metabolic energy was diminished by sulfobromophthalein. A specific transport system plays a major role in the secretion of SN-38 and that this secretory transport system predominantly exists in the ileum. Uptake of SN-38 was significantly reduced at 4 degrees C. Baicalin inhibited the uptake of SN-38. A specific transport system mediates the uptake of SN-38 across the apical membrane in Caco-2 cells. Inhibition of this transporter would be a useful means for reducing late-onset diarrhea.

Prevention of irinotecan associated diarrhea by intestinal alkalization. A pilot study in gastrointestinal cancer patients

AIM AND BACKGROUND

Intestinal alkalization could prevent irinotecan associated diarrhea modulating some chemical equilibria between irinotecan metabolites. The aim of this study was to evaluate the efficacy of this procedure in advanced gastrointestinal cancer patients (GICP).

MATERIALS AND METHOD

In this prospective study advanced GICP, receiving irinotecan based chemotherapy regimens, were well trained to add sodium bicarbonate to the water intake in order to accomplish intestinal alkalization.

RESULTS

A total of twenty four advanced GICP were enrolled. Grade III-IV diarrhea has been observed in four patients (16%), some of whom had several risk factors for diarrhea. Only one out of seventeen colorectal cancer patients, receiving the irinotecan combination as first line therapy, had grade III-IV diarrhea. No side effects of the procedure have been appreciated.

CONCLUSIONS

Intestinal alkalization may be effective as a preventive treatment for irinotecan associated diarrhea in chemotherapy regimens used in GICP. This procedure deserves further investigation.

Adsorption of irinotecan onto oral adsorbent AST-120 (Kremezin) for preventing delayed diarrhea

PURPOSE

One of the significant dose-limiting toxicities of irinotecan hydrochloride (CPT-11) is severe diarrhea due to impairment of the intestinal membrane induced by the excreted CPT-11 and its metabolites. AST-120 (Kremezin) is a prominent oral adsorbent that consists of porous spherical carbonic particles. To evaluate whether Kremezin can prevent the diarrhea induced by CPT-11, we investigated the adsorption characteristics of CPT-11 and its metabolites onto Kremezin in vitro and in vivo.

METHODS

For in vitro studies, Kremezin was added to each solution containing one of the camptothecin drugs (CPT-11, SN-38, and SN-38-glucuronide), and adsorption activities were determined under various conditions. For in vivo studies, CPT-11 was consecutively administered, and the occurrence of diarrhea was compared between Kremezin-treated and non-treated rats.

RESULTS

Kremezin drastically adsorbed the camptothecin drugs in vitro, and the adsorption percentages of the camptothecin drugs for 60 min were more than 85%. In addition, the frequency of diarrhea in Kremezin-treated rats decreased by approximately half of that in the non-treated rats.

CONCLUSION

Kremezin showed potent adsorption capacities for the camptothecin drugs and mitigated the symptoms of diarrhea in rats. These results suggest that Kremezin is useful to prevent the diarrhea in clinical CPT-11 chemotherapy.

Cefixime Allows Greater Dose Escalation of Oral Irinotecan: A Phase I Study in Pediatric Patients With Refractory Solid Tumors

Purpose

Irinotecan is active against a variety of malignancies; however, severe diarrhea limits its usefulness. In our phase I study, the intravenous formulation of irinotecan was administered orally daily for 5 days for 2 consecutive weeks (repeated every 21 days) to children with refractory solid tumors. Our objectives were to determine the maximum-tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of oral irinotecan and to evaluate whether coadministration of cefixime (8 mg/kg/d beginning 5 days before irinotecan and continuing throughout the course) ameliorates irinotecan-induced diarrhea.

Patients and Methods

In separate cohorts, irinotecan doses were escalated from 15 to 45 mg/m2/d without cefixime and then from 45 to 60 and 75 mg/m2/d with cefixime.

Results

Without cefixime, diarrhea was dose limiting at irinotecan 45 mg/m2/d. Myelotoxicity was not significant at any dose. The MTD was 40 mg/m2/d without cefixime but 60 mg/m2/d with cefixime. Systemic exposure to SN-38 at the MTD was significantly higher with cefixime than without cefixime (mean SN-38 area under the curve: 19.5 ng×h/mL; standard deviation [SD], 6.8 ng × h/mL v 10.4 ng × h/mL; SD, 4.3 ng × h/mL, respectively; P = .030).

Conclusion

Cefixime administered with oral irinotecan is well tolerated in children and allows greater dose escalation of irinotecan. Because diarrhea is a major adverse effect of both intravenous and oral irinotecan, further evaluation of the use of cefixime to ameliorate this adverse effect is warranted.

Optimal antidiarrhea treatment for antitumor agent irinotecan hydrochloride (CPT-11)-induced delayed diarrhea

PURPOSE

An antitumor camptothecin derivative CPT-11 has proven a broad spectrum of solid tumor malignancy, but its severe diarrhea has often limited its more widespread use. We have demonstrated from a rat model that intestinal beta-glucuronidase may play a key role in the development of CPT-11-induced delayed diarrhea by the deconjugation of the luminal SN-38 glucuronide, and the elimination of the intestinal microflora by antibiotics or dosing of TJ-14, a Kampo medicine that contains beta-glucuronidase inhibitor baicalin, exerted a protective effect. In the present study, we assessed the efficacy of several potential treatments in our rat model to clarify which is the most promising treatment for CPT-11-induced delayed diarrhea.

METHODS AND RESULTS

Oral dosing (twice daily from days -1 to 4) of streptomycin 20 mg/kg and penicillin 10 mg/kg (Str/Pen), neomycin 20 mg/kg and bacitracin 10 mg/kg (Neo/Bac), both of which inhibited almost completely the fecal beta-glucuronidase activity, or TJ-14 1,000 mg/kg improved the decrease in body weight and the delayed diarrhea symptoms induced by CPT-11 (60 mg/kg i.v. from days 1 to 4) to a similar extent. The efficacy was less but significant in activated charcoal (1,000 mg/kg p.o. twice daily from days -1 to 4). In a separate experiment using rats bearing breast cancer (Walker 256-TC), TJ-14, Neo/Bac, and charcoal at the same dose regimen improved CPT-11-induced intestinal toxicity without reducing CPT-11's antitumor activity. In contrast, oral dosing (twice a day) of cyclosporin A (50 mg/kg), a P-glycoprotein and cMOAT/MRP2 inhibitor or valproic acid (200 mg/kg), a UDP-glucuronosyltranferase inhibitor, exacerbated the intestinal toxicity without modifying CPT-11's antitumor activity.

CONCLUSIONS

The result clearly demonstrated the ability of Neo/Bac, Str/Pen, and TJ-14, less but significant ability of activated charcoal, to ameliorate CPT-11-induced delayed-onset diarrhea, suggesting the treatments decreasing the exposure of the intestines to the luminal SN-38 are valuable for improvement of CPT-11-induced intestinal toxicity. In contrast, the treatments affecting the biliary excretion of CPT-11 and its metabolites might have undesirable results.

A phase I/II trial of irinotecan-cisplatin combined with an anti-late-diarrhoeal programme to evaluate the safety and antitumour response of this combination therapy in patients with advanced non-small-cell lung cancer

We conducted a phase I/II study in patients with advanced non-small-cell lung cancer (NSCLC) to increase the therapeutic index of the cisplatin–irinotecan combination by institution of an anti-late-diarrhoeal program (ADP). A total of 77 chemotherapy-naive patients with advanced NSCLC were enrolled. The cisplatin dose was fixed at 60 mg m⁻² (Day 1). Irinotecan was escalated in 5 mg m⁻² increments, starting from 60 mg m⁻² (Days 1 and 8). ADP consisted of oral sodium bicarbonate, magnesium oxide, basic water, and ursodeoxycholic acid, and was administered orally for 4 days with each dose of irinotecan. In the phase I portion, irinotecan pharmacokinetics was also examined. After the recommended dose of irinotecan with ADP was determined, a phase II study was conducted to evaluate the response. Maximum tolerated dose was reached at an irinotecan dose of 80 mg m⁻² (Grade 4 diarrhoea and neutropenia). Pharmacokinetic studies show that the maximum concentration and the area under the curve of both irinotecan and SN38 (active metabolite of irinotecan) tend to increase in the dose-dependent manner of irinotecan. The phase II portion of the study included 48 patients, who were treated with 75 mg m⁻² of irinotecan. Grade 3/4 toxicities included neutropenia in 65%, leucopenia in 33%, and late diarrhoea in 6% of the patients. During this treatment, PS did not change in 65% of patients. At the end of the chemotherapy, PS did not decline in 90% of patients. In the phase II portion, a response occurred in 63% (95% confidential interval (CI), 47–76%) of patients. Median time to progression was 19 weeks (95% CI, 15–22 weeks), and median survival was 52 weeks (95% CI, 39–64 weeks). This regimen of irinotecan and cisplatin with ADP resulted in promising efficacy with acceptable toxicity for patients with advanced NSCLC. This regimen is a candidate for the experimental arm towards future phase III studies.

Enhancement of DNA topoisomerase I inhibitor–induced apoptosis by ursodeoxycholic acid

Certain hydrophobic bile acids, including deoxycholic acid and chenodeoxycholic acid, exert toxic effects not only in the liver but also in the intestine. Moreover, ursodeoxycholic acid (UDCA), which has protective actions against apoptosis in the liver, may have both protective and toxic effects in the intestine. The goal of the present study was to clarify the mechanisms responsible for the toxic effect of UDCA in intestinal HT-29 cells. Here, we show that UDCA potentiated both phosphatidylserine externalization and internucleosomal DNA fragmentation induced by SN-38, the most potent metabolite of the DNA topoisomerase I inhibitor, CPT-11. Furthermore, the loss of mitochondrial membrane potential as well as mitochondrial membrane permeability transition induced by SN-38 was enhanced in the presence of UDCA, resulting in an increased lethality determined by colony-forming assay. This UDCA-induced increased apoptosis was not due to alteration of either intracellular accumulation of SN-38 or cell cycle arrest by SN-38. The increased apoptosis was best observed when UDCA was present after SN-38 stimulation and was independent of caspase-8 but dependent on caspase-9 and caspase-3 activation. Furthermore, UDCA enhanced SN-38-induced c-Jun NH(2)-terminal kinase activation. In conclusion, UDCA increases the apoptotic effects while decreasing the necrotic effects of SN-38 when added after the topoisomerase I inhibitor, showing potential clinical relevance as far as targeted cell death and improved wound healing are concerned. However, the use of this bile acid as an enhancer in antitumor chemotherapy should be further evaluated clinically.

Pharmacokinetic Changes of Irinotecan by Intestinal Alkalinization in an Advanced Colorectal Cancer Patient

The prevention of irinotecan (CPT-11)-induced diarrhea, a well-known adverse reaction to the drug, by treatment with intestinal alkalinization has been carried out in patients with colorectal cancer in Japan. Under acidic conditions, CPT-11 and its active metabolite, SN-38, exists preferably as the lactone form, whereas both exist as the carboxylate form under basic conditions. It has been suggested that the lactone forms of both CPT-11 and SN-38 are diffused passively across the intestinal mucosal membranes, whereas the carboxylate forms are actively transported. The intestinal uptake rate of both forms appears to be pH sensitive under physiological conditions, but it remains unclear whether intestinal alkalinization treatment affects the pharmacokinetics of CPT-11 and SN-38. This study was designed to evaluate the pharmacokinetics of CPT-11 and SN-38 in a colorectal cancer patient with or without alkalinization treatment. We found that intestinal alkalinization significantly decreased the plasma levels of CPT-11 and SN-38. In particular, the AUC of SN-38 was markedly decreased to 56 from 107 ng.h/mL. Intestinal alkalinization was effective in preventing CPT-11-induced diarrhea, but this treatment changed the pharmacokinetics of CPT-11 and SN-38 in the body.

Prevention of Irinotecan-Induced Diarrhea by Oral Sodium Bicarbonate and Influence on Pharmacokinetics

Alkalization of the intestinal tract by oral administration of sodium bicarbonate has been reported to be a promising method for preventing delayed diarrhea, a dose-limiting toxicity in patients receiving chemotherapy with irinotecan hydrochloride. However, it is feared that this method may adversely affect the pharmacokinetics of irinotecan by inhibiting its intestinal absorption and that of its active metabolites. We compared the pharmacokinetics and toxicity of irinotecan with and without oral alkalization in a cross-over study that enrolled 10 colorectal cancer patients. We found that alkalization did not decrease the blood levels of irinotecan and its active metabolite. In fact, the area under concentration versus time curves (AUCs) of irinotecan and 7-ethyl-10-hydroxycamptothecin glucuronide (SN-38G) were statistically equivalent both with and without oral alkalization. Also, the AUC of SN-38 with alkalization was statistically equivalent or larger than that without alkalization. Oral alkalization reduced the incidence of diarrhea and gastrointestinal symptoms, and these adverse effects were not worsened by long-term administration. These results suggest that oral alkalization can control diarrhea and gastrointestinal toxicity without decreasing the blood levels of irinotecan and its active metabolites, thus improving the tolerability of long-term chemotherapy without reducing efficacy.

Management of chemotherapy-induced nausea, vomiting, oral mucositis, and diarrhoea

The past 10 years have seen substantial advances in molecularly targeted therapies for treatment of patients with cancer; however, chemotherapy will continue to be used. Therefore, the toxic effects of chemotherapy must be readily managed-especially nausea, vomiting, mucositis, and diarrhoea. For moderately to highly emetogenic chemotherapy, standard prophylactic treatment is an antagonist for 5-hydroxytryptamine 3 receptors (5-HT3R) combined with dexamethasone for the acute phase, and dexamethasone with another agent for prevention of the delayed phase. Palonoestron (a 5-HT3R antagonist) and aprepitant (an antagonist for the protachykinin 1 receptor) have been introduced for the prevention of emesis. Other agents such as cannabinoids, gabapentin, and olanzapine might also be effective. There is no standard prophylactic regimen for chemotherapy-induced mucositis. The most common treatment is optimum care of the mouth by use of mouthwashes. Keratinocyte growth factor, molgromastim, and transforming growth factor beta3 may also reduce chemotherapy-induced mucositis. Severe diarrhoea is another potentially fatal complication of chemotherapy and is most common in patients treated with irinotecan. Several interventions have been assessed for prevention and treatment of diarrhoea such as high-dose loperamide, non-absorbable antibiotics, budesonide, thalidomide, and fish oils, but only loperamide is used routinely. Symptom management has become a focus of clinical research, and development of personalised medicine should identify patients at increased risk of toxic effects because of molecular or biochemical factors, thus leading to changes in dose, early intervention, or use of alternative therapies.

Phase II Study of Activated Charcoal to Prevent Irinotecan-Induced Diarrhea

Purpose

The dose-limiting toxicity of irinotecan (CPT-11; Camptosar) is delayed-onset diarrhea, with an incidence at the grade 3 to 4 level of 20% to 35%. SN38, its active moiety, is responsible by a direct effect on mucosal topoisomerase-I. The aim of this study was to assess whether activated charcoal (AC), possibly by adsorbing free lumenal SN38, can reduce irinotecan-induced diarrhea (CID) and optimize its dose-intensity.

Patients and Methods

Patients with advanced colorectal cancer receiving irinotecan 125 mg/m2intravenously once a week for 4 weeks every 6 weeks were studied. In cycle 1, patients received irinotecan plus AC (5 mL aqueous Charcodote [1,000 mg AC] plus 25 mL water) given the evening before the irinotecan dose and then tid for 48 hours after the dose. In cycle 2, no AC was given. National Cancer Institute Common Toxicity Criteria diarrhea grade, irinotecan dose-intensity, and loperamide consumption were recorded prospectively in both cycles.

Results

Twenty-eight patients had completed cycle 1 with AC; 24 subsequently completed cycle 2 without AC. Grade 3 to 4 diarrhea was 7.1% v 25%, and grade 0 diarrhea was 46.4% v 20.8% in cycles 1 and 2, respectively. Median percent planned dose delivered was 98% v 70% in cycles 1 and 2, respectively. In cycles 1 and 2, respectively, 25% v 54% patients took more than 10 loperamide tablets. AC was well tolerated with excellent compliance.

Conclusion

The administration of AC with irinotecan reduced the incidence of grade 3 to 4 diarrhea and antidiarrheal medication consumption and increased irinotecan dose-intensity. Prophylactic AC may have a role in reducing dose-limiting CID and optimizing irinotecan therapy.

New approaches to prevent intestinal toxicity of irinotecan-based regimens

BACKGROUND

Irinotecan is a selective inhibitor of topoisomerase I, an enzyme part of the replication and transcription system of DNA. Irinotecan is employed, with different modalities, in the treatment of metastatic colorectal cancer, and recently it has been officially approved in association with fluorouracil (FU) and leucovorin (LV) as a first-line option in metastatic colorectal cancer.

RESULTS

One of the problems linked to the administration of this drug is the high intestinal toxicity, which constitutes its dose limiting toxicity (DLT). In routine practice, loperamide is employed as symptomatic drug for the treatment of CPT-11-induced diarrhoea, but is not completely adequate to control the problem. The role of the intestinal bacterial microflora in the pathogenesis of CPT-11-induced intestinal toxicity has been recently discovered. The active metabolite of CPT-11, SN38, is generated from CPT-11 by sieric carboxylesterase, and subsequently conjugated to SN38-G by hepatic UDP-glucuronyltransferase. SN38-G is the inactive metabolite of CPT-11 and is excreted into the small intestine, from which it is eliminated in the faeces. Some studies have shown the ability of intestinal bacterial beta-glucoronidases to transform SN38-G into SN38, causing direct damage to the intestinal mucosa. Thus, alternative strategies such as intestinal alkalinization and anti-cyclooxygenase 2 (COX-2) therapy have been explored.

CONCLUSIONS

In this review, we will illustrate the mechanisms which cause the CPT-11-induced diarrhoea and the potential measures available to prevent it.

Recommended guidelines for the treatment of cancer treatment-induced diarrhea

PURPOSE

To update and expand on previously published clinical practice guidelines for the treatment of cancer treatment-induced diarrhea.

METHODS

An expert multidisciplinary panel was convened to review the recent literature and discuss recommendations for updating the practice guidelines previously published by this group in the Journal of Clinical Oncology in 1998. MEDLINE searches were performed and the relevant literature published since 1998 was reviewed by all panel members. The treatment recommendations and algorithm were revised by panel consensus.

RESULTS

A recent review of early toxic deaths occurring in two National Cancer Institute-sponsored cooperative group trials of irinotecan plus high-dose fluorouracil and leucovorin for advanced colorectal cancer has led to the recognition of a life-threatening gastrointestinal syndrome and highlighted the need for vigilant monitoring and aggressive therapy for this serious complication. Loperamide remains the standard therapy for uncomplicated cases. However, the revised guidelines reflect the need for recognition of the early warning signs of complicated cases of diarrhea and the need for early and aggressive management, including the addition of antibiotics. Management of radiation-induced diarrhea is similar but may not require hospitalization, and chronic low- to intermediate-grade symptoms can be managed with continued loperamide.

CONCLUSION

With vigilant monitoring and aggressive therapy for cancer treatment-induced diarrhea, particularly in patients with early warning signs of severe complications, morbidity and mortality may be reduced.

Weekly administration of irinotecan (CPT-11) plus cisplatin for refractory or relapsed small cell lung cancer

PURPOSE

Weekly administrations of CPT-11 plus cisplatin together with an anti-diarrheal program, the Oral Alkalization and Control of Defecation [Int J Cancer 1999;83:491; Int J Cancer 2001;92:269; Cancer Res 2002;62:179], were evaluated in this phase II study for patients with refractory or relapsed small cell lung cancer.

METHODS

Patients were treated by weekly administrations of 60 mg/m(2) CPT-11 plus 30 mg/m(2) cisplatin on Days 1, 8 and 15 over 4 weeks. Coinciding with the infusions and for 4 days thereafter, the anti-diarrheal program was practiced using orally administered sodium bicarbonate, magnesium oxide and basic water.

RESULTS

Twenty-five patients who had prior treatments of etoposide and platinum containing regimens (16 refractory patients and nine relapsed patients) were entered. The mean dose-intensities of CPT-11 and cisplatin were 154.8 and 77.4 mg/m(2) per course, respectively. Therefore, 86% of the planned dose was delivered. There were 20 partial responses and an overall response rate of 80% (95% confidence interval, 62-96%) was obtained. The median time to progression and the median survival after starting this regimen were 3.6 and 7.9 months, respectively. The major toxicity was myelosuppression. Grades 3 and 4 neutropenia occurred in 24 and 12% of patients, respectively. One patient with febrile neutropenia was experienced, and Grade 3 diarrhea was observed in 8%. But there was no treatment death.

CONCLUSION

Weekly administrations of CPT-11 plus cisplatin together with Oral Alkalization and Control of Defecation provide a practical and well tolerated regimen that was active for refractory or relapsed small cell lung cancer.

Irinotecan: mechanisms of tumor resistance and novel strategies for modulating its activity

Camptothecins are broad-spectrum anticancer drugs that specifically target DNA topoisomerase I (Topo I). The formation of a cleavable drug-Topo I-DNA complex results in lethal double-strand DNA breakage and cell death. However, de novo or acquired clinical resistance to camptothecins is common. Studies of the camptothecin analog irinotecan suggest the following general mechanisms of resistance: (i) variable levels of the enzymes involved in the conversion of irinotecan; (ii) reduced cellular accumulation from active drug efflux; (iii) reduced levels of Topo I expression; (iv) alterations in the structure of Topo I from different mutations; (v) alterations in the cellular response to camptothecin-Topo I-DNA complex formation, which involves proteasome degradation of Topo I and/or enhanced DNA repair; and (vi) activation of the transcription factor nuclear factor kappa B by DNA damage and subsequent suppression of apoptosis. Multiple approaches using pharmacological and biological modulation to circumvent the above mechanisms of resistance have been incorporated into ongoing clinical trials and are expected to enhance the antitumor activity of irinotecan and reduce its systemic toxicity.

Phase I clinical trial of irinotecan with oral capecitabine in patients with gastrointestinal and other solid malignancies

The purpose of this study was to determine the safety of irinotecan and capecitabine in patients with advanced solid tumors. Thirty-four patients received 122 courses of irinotecan 200 to 300 mg/m(2) as an intravenous infusion during 30 minutes on day 1 and capecitabine 1,500 to 3,000 mg/d orally 12 hours apart starting on day 2 for 14 days, repeated every 21 days (one course). Three to seven patients were treated in six dose-escalation cohorts. Three of 7 (43%) patients treated with irinotecan 300 mg/m(2) and capecitabine 2,300 mg/d had course 1 dose-limiting toxicity (DLT) defining maximum tolerated dosage (MTD). Fatigue and diarrhea were the major DLTs, and other events included neutropenia, anorexia, and hand-foot syndrome. At one dose level below the MTD, none of 7 patients treated with irinotecan 275 mg/m(2), and capecitabine 2,300 mg/d (36 courses) had course 1 DLT. Grade III to IV toxicities beyond course 1 included neutropenia (11% of all courses), fatigue (3.4%) and hand-foot syndrome (3.4%). There were only two episodes of febrile grade II neutropenia. There were no toxic deaths. Transient antitumor response was noted in one patient with irinotecan and 5-fluorouracil-refractory colon cancer. The combination of irinotecan 275 mg/m(2) and capecitabine 2,300 mg/d represents a safe, favorable, and convenient outpatient regimen warranting further phase II evaluation.