Renal function as a predictor of irinotecan-induced neutropenia

Local administration of irinotecan using an implantable drug delivery device stops high-grade glioma tumor recurrence in a glioblastoma tumor model

The treatment for Glioblastoma is limited due to the presence of the blood brain barrier, which restricts the entry of chemotherapeutic drugs into the brain. Local delivery into the tumor resection margin has the potential to improve efficacy of chemotherapy. We developed a safe and clinically translatable irinotecan implant for local delivery to increase its efficacy while minimizing systemic side effects. Irinotecan-loaded implants were manufactured using hot melt extrusion, gamma sterilized at 25 kGy, and characterized for their irinotecan content, release, and drug diffusion. Their therapeutic efficacy was evaluated in a patient-derived xenograft mouse resection model of glioblastoma. Their safety and translatability were evaluated using histological analysis of brain tissue and serum chemistry analysis. Implants containing 30% and 40% w/w irinotecan were manufactured without plasticizer. The 30% and 40% implants showed moderate local toxicity up to 2- and 6-day post-implantation. Histopathology of the implantation site showed signs of necrosis at days 45 and 14 for the 30% and 40% implants. Hematological analysis and clinical chemistry showed no signs of serious systemic toxicity for either implant. The 30% implants had an 80% survival at day 148, with no sign of tumor recurrence. Gamma sterilization and 12-month storage had no impact on the integrity of the 30% implants. This study demonstrates that the 30% implants are a promising novel treatment for glioblastoma that could be quickly translated into the clinic.

Pharmacokinetic profile of irinotecan in patients with chronic kidney disease: Two cases and literature review

AIMS

There are limited pharmacokinetic data on the use of irinotecan in patients with reduced glomerular filtration rate (GFR) and no haemodialysis. In this case report, we present 2 cases and review the current literature.

METHODS

The dose of irinotecan in both patients was reduced pre-emptively due to reduced GFR. The first patient had her irinotecan dose reduced to 50%, but was nevertheless admitted to hospital because of irinotecan-induced toxicity, including gastrointestinal toxicity and neutropenic fever. The dose was reduced further to 40% for the second cycle; however, the patient was again admitted to the hospital, and irinotecan was stopped indefinitely. The second patient also had his irinotecan dose reduced to 50% and was admitted to the emergency department for gastrointestinal toxicity after the first cycle. However, irinotecan could be administered in the same dose in later cycles.

RESULTS

The area under the curve to infinity of irinotecan and SN-38 in the first patient were comparable to those of an individual receiving 100% dose intensity. The area under the curve to infinity of irinotecan and SN-38 in patient 2 in both cycles were slightly less than reference values. Furthermore, clearance values of irinotecan and SN-38 in our patients were comparable to those without renal impairment.

CONCLUSION

Our case report suggests that reduced GFR may not significantly affect the clearance of irinotecan and SN-38, but can still result in clinical toxicity. Reduced initial dosing seems indicated in this patient population. Further research is needed to fully understand the relationship between reduced GFR, pharmacokinetics, and toxicity of irinotecan and SN-38.

Case report: Changes in serum bevacizumab concentration in a hemodialysis patient with unresectable colorectal cancer treated with FOLFIRI plus bevacizumab

The global incidence of colorectal cancer (CRC) in patients receiving hemodialysis is steadily rising. However, current information on the clinical use of chemotherapy for patients undergoing hemodialysis with CRC is limited. Herein, we describe a clinical course of a 74-year-old patient undergoing hemodialysis with unresectable CRC treated with folinic acid, 5-fluorouracil (5FU), and irinotecan (FOLFIRI) plus bevacizumab whose changes in serum bevacizumab concentration were analyzed. Treatment was initiated with a standard dosage of 5-FU and 80% of the standard dose of irinotecan to avoid any adverse events. However, neutropenia (grade 4) was observed after five treatment cycles, which prompted a dose reduction of 5-FU and irinotecan, after which treatment was safely completed. Progression-free survival of the patient was 7.5 months. Changes in serum bevacizumab concentration were similar to those documented in patients with normal renal function. In addition, no bevacizumab-related adverse events occurred. It was inferred that FOLFIRI plus bevacizumab therapy could be implemented as a safe and efficient treatment for patients undergoing hemodialysis with unresectable CRC. To the best of our knowledge, this is the first report of the analysis of serum bevacizumab concentrations in a patient undergoing hemodialysis with unresectable CRC.

Minimal contribution of the hepatic uptake transporter OATP1B1 to the inter-individual variability in SN-38 pharmacokinetics in cancer patients without severe renal failure

PURPOSE

SN-38, a pharmacologically active metabolite of irinotecan, is taken up into hepatocytes by organic anion transporting polypeptide (OATP) 1B1. The effects of functional OATP1B1 521T>C on the pharmacokinetics of SN-38 remain controversial. Here, we prospectively examined the effects of OATP1B1 function on the area under the plasma total or unbound concentration-time curve (tAUC or uAUC) of SN-38 by assessing OATP1B1 521T>C and the plasma levels of endogenous OATP1B1 substrates, coproporphyrin (CP)-I and III, in cancer patients treated with irinotecan.

METHODS

We enrolled cancer patients who were treated with an irinotecan-containing regimen and did not have severe renal failure. The total and unbound concentrations of SN-38 in the plasma were measured by high-performance liquid chromatography. AUC values were calculated and normalized to the actual irinotecan dose (AUC/dose). The OATP1B1 521T>C was analyzed by direct sequencing. Concentrations of the endogenous substrates in plasma before irinotecan treatment (baseline) were determined by liquid chromatography with tandem mass spectrometry.

RESULTS

Twenty-two patients with a median estimated glomerular filtration rate of 74.8 mL/min (range 32.6-99.6) were examined. Both tAUC/dose and uAUC/dose were associated with the grade of neutropenia; however, they were not associated with OATP1B1 521T>C or baseline CP-I and III levels. It is worth noting that these baseline concentrations were significantly higher in patients with OATP1B1 521C, supporting functional changes in OATP1B1.

CONCLUSION

The contribution of OATP1B1 activity to inter-patient variability in the systemic exposure to SN-38 is likely minimal in patients without severe renal failure.

Decreased Disposition of Anticancer Drugs Predominantly Eliminated via the Liver in Patients with Renal Failure

Background:

Evidence has revealed that renal impairment can affect the systemic exposure of drugs which are predominantly eliminated via the liver. The modulation of drug-metabolizing enzymes and transporters expressed in the liver and/or small intestine by diverse entities, including uremic toxins, in systemic circulation of patients with severe renal failure is considered as the cause of atypical pharmacokinetics, which sometimes induce undesirable adverse events that are especially critical for drugs with narrow therapeutic window such as anticancer drugs. A dosing strategy for anticancer drugs in these patients needs to be established.

Methods:

The effects of renal impairment on the systemic exposure and safety of anticancer drugs were summarized. The proposed mechanisms for the alterations in the pharmacokinetics of these anticancer drugs were also discussed.

Results:

Changes in pharmacokinetics and clinical response were reported in 9 out of 10 cytotoxic anticancer drugs investigated, although available information was limited and sometimes controversial. Systemic exposure of 3 out of 16 tyrosine kinase inhibitors was higher in patients with severe renal failure than that in patients with normal kidney function. An increase in systemic exposure of anticancer drugs in patients with renal impairment is likely to be observed for substrates of OATP1B1, despite the limited evidence.

Conclusion:

The molecular basis for the effect of uremia on non-renal drug elimination still needed to be clarified with further studies to generate generalizable concepts, which may provide insights into establishing better clinical usage of anticancer drugs, i.e. identifying patients at risk and dose adjustment.

Uremic serum residue decreases SN-38 sensitivity through suppression of organic anion transporter polypeptide 2B1 in LS-180 colon cancer cells

Pharmacokinetics of SN-38 in patients with end-stage kidney disease (ESKD) is partially varied because of fluctuations in transporters expression and/or function by high protein bound-uremic toxins concentration. The fluctuations may induce variations in anticancer drugs sensitivity to cancer cells. We aimed to clarify the variations in sensitivity of SN-38 to cancer patients with ESKD and investigate this mechanism, by human colon cancer cells exposed to uremic serum residue. LS180 cells were exposed to normal or uremic serum residue (LS/NSR or LS/USR cells) for a month. IC₅₀ values of SN-38 in LS/NSR or LS/USR cells were calculated from viability of each cells treated SN-38. mRNA expression and intracellular SN-38 accumulation was evaluated by RT-PCR and HPLC-fluorescence methods, respectively. The IC₅₀ value in LS/USR cells was higher than that in LS/NSR cells. Organic anion transporter polypeptide (OATP) 2B1 mRNA expression was lower in LS/USR cells than in LS/NSR cells, and SN-38 accumulation in LS/USR cells was lower than that in LS/NSR cells. Only co-treatment baicalin, which is OATP2B1 inhibitor, almost negated the difference in SN-38 accumulation between LS/NSR and LS/USR. Anticancer effects of substrates of OATP2B1, such as SN-38, were reduced in ESKD patients at the same plasma substrate concentration.

Acceleration of carboxylesterase-mediated activation of irinotecan to SN-38 by serum from patients with end-stage kidney disease

PURPOSE

Pharmacokinetics and pharmacodynamics of irinotecan have been reported to be altered in cancer patients with end-stage kidney disease (ESKD). Carboxylesterase (CES) has an important role in metabolism of irinotecan to its active metabolite, SN-38, in human liver. The purpose of the present study was to investigate whether CES activity was altered in ESKD patients.

METHODS

The present study investigated the effects of uremic serum, uremic toxins, and fatty acids on the hydrolysis of irinotecan and a typical CES substrate, p-nitrophenyl acetate (PNPA), in human liver microsomes. Normal and uremic serum samples were deproteinized by treatment with methanol were used in the present study.

RESULTS

The present study showed that both normal and uremic serum significantly inhibited CES-mediated metabolism of both irinotecan and PNPA. The inhibition by uremic serum was weaker than that by normal serum, suggesting that CES activity may be higher in ESKD patients. Although four uremic toxins did not affect PNPA metabolism, arachidonic acid inhibited it. There was no difference in inhibitory effect of PNPA metabolism between both mixtures of seven fatty acids used at concentrations equivalent to those present in 10% normal or uremic serum. Interestingly, those mixtures had a more pronounced effect than either 10% normal or uremic serum.

CONCLUSIONS

The present study showed that the inhibition of CES activity by uremic serum was weaker than that by normal serum, suggesting that an increase in maximum plasma concentration of SN-38 in cancer patients with ESKD can be attributed to an accelerated CES-mediated irinotecan hydrolysis.

Microbiota-derived uremic retention solutes: perpetrators of altered nonrenal drug clearance in kidney disease

INTRODUCTION

Scientific interest in the gut microbiota is increasing due to improved understanding of its implications in human health and disease. In patients with kidney disease, gut microbiota-derived uremic toxins directly contribute to altered nonrenal drug clearance. Microbial imbalances, known as dysbiosis, potentially increase formation of microbiota-derived toxins, and diminished renal clearance leads to toxin accumulation. High concentrations of microbiota-derived toxins such as indoxyl sulfate and p-cresol sulfate perpetrate interactions with drug metabolizing enzymes and transporters, which provides a mechanistic link between increases in drug-related adverse events and dysbiosis in kidney disease. Areas covered: This review summarizes the effects of microbiota-derived uremic toxins on hepatic phase I and phase II drug metabolizing enzymes and drug transporters. Research articles that tested individual toxins were included. Therapeutic strategies to target microbial toxins are also discussed. Expert commentary: Large interindividual variability in toxin concentrations may explain some differences in nonrenal clearance of medications. Advances in human microbiome research provide unique opportunities to systematically evaluate the impact of individual and combined microbial toxins on drug metabolism and transport, and to explore microbiota-derived uremic toxins as potential therapeutic targets.

Benefit of early inflow exclusion during living donor liver transplantation for unresectable hepatoblastoma

BACKGROUND

Hepatoblastoma (HB) is a highly malignant primary liver tumor in children. Although liver transplantation (LT) is an effective treatment for unresectable HB with good long-term outcomes, post-transplant survival is mainly affected by recurrence, despite adjuvant chemotherapy. Novel strategies are needed to improve the outcomes in patients undergoing LT for unresectable HB.

PATIENTS AND METHODS

Twelve children received LT for unresectable HB. In 9 patients, we applied early exclusion of hepatic inflow (hepatic artery and portal vein) and creation of a temporary portocaval shunt during LT.

RESULT

There were differences in the duration of and the blood loss during operation as compared with previously reports. The estimated glomerular filtration rate was well preserved at 3, 6, and 12months and the latest follow-up after LT, and the recurrence-free survival was 88.9%.

CONCLUSION

Early inflow control during LT for unresectable HB may benefit recurrence-free survival by minimizing blood loss and tumor dissemination, preserving renal function and allowing early adjuvant chemotherapy.

Irinotecan, a key chemotherapeutic drug for metastatic colorectal cancer

Irinotecan hydrochloride is a camptothecin derivative that exerts antitumor activity against a variety of tumors. SN-38 produced in the body by carboxylesterase is the active metabolite of irinotecan. After irinotecan was introduced for the treatment of metastatic colorectal cancer (CRC) at the end of the last century, survival has improved dramatically. Irinotecan is now combined with 5-fluorouracil, oxaliplatin and several molecularly-targeted anticancer drugs, resulting in the extension of overall survival to longer than 30 mo. Severe, occasionally life-threatening toxicity occurs sporadically, even in patients in relatively good condition who have a low risk of chemotherapy-induced toxicity, often causing the failure of irinotecan-based chemotherapy. Clinical pharmacological studies have revealed that such severe toxicity is related to exposure to SN-38 and genetic polymorphisms in UDP-glucuronosyltransferase 1A1 gene. The large inter- and intra-patient variability in systemic exposure to SN-38 is determined not only by genetic factors but also by physiological and environmental factors. This review first summarizes the roles of irinotecan in chemotherapy for metastatic CRC and then discusses the optimal dosing of irinotecan based on the aforementioned factors affecting systemic exposure to SN-38, with the ultimate goal of achieving personalized irinotecan-based chemotherapy.

Irinotecan and temozolomide for treatment of neuroblastoma in a patient with renal failure on hemodialysis

Renal failure is a rare complication of neuroblastoma or its therapy. To our knowledge, no reports describe treatment of children with neuroblastoma with chemotherapy in the setting of renal failure and maintenance hemodialysis. We report a 6-year-old child with high-risk neuroblastoma who developed renal failure requiring long-term hemodialysis. She was subsequently treated with 13 cycles of intravenous irinotecan 20 mg/m(2)/day and oral temozolomide 100 mg/m(2)/day for 5 days before disease progression without any dose adjustments, transfusions, febrile neutropenia or diarrhea. This case demonstrates that irinotecan and temozolomide can be safely administered in children with renal failure requiring hemodialysis.

Direct inhibition and down-regulation by uremic plasma components of hepatic uptake transporter for SN-38, an active metabolite of irinotecan, in humans

PURPOSE

Clinical study has previously revealed that plasma concentration of 7-ethyl-10-hydroxycamptothecin (SN-38), an active metabolite of irinotecan, was higher in patients with end-stage renal failure than those with normal kidney function although SN-38 is mainly eliminated in the liver. Here, we focused on inhibition by uremic toxins of hepatic SN-38 uptake and down-regulation of uptake transporter(s) by uremic plasma in humans.

METHODS

We evaluated SN-38 uptake and its inhibition by uremic toxins, 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), indoxyl sulfate (Indox), hippuric acid (HA) and indole acetate (IA), with cryopreserved human hepatocytes and HEK293 cells stably expressing hepatic uptake transporters, organic anion transporting polypeptides (OATPs). We also collected plasma samples from patients with severe renal failure to examine their effects on mRNA level of OATPs in primary cultured human hepatocytes.

RESULTS

SN-38 was taken up by hepatocytes, which showed biphasic saturation patterns. The SN-38 uptake by hepatocytes was significantly inhibited by a uremic toxin mixture including clinically relevant concentrations of CMPF, Indox, HA and IA. Kinetic analyses for OATP-mediated transport revealed that the uptake of SN-38 by OATP1B1 was the highest, followed by OATP1B3. Among the uremic toxins, CMPF exhibited most potent inhibition of OATP1B1-mediated SN-38 uptake and directly inhibited the uptake of SN-38 also in hepatocytes. In addition, gene expression of OATP1B1 and OATP1B3 in hepatocytes was significantly down-regulated by the treatment with the uremic plasma.

CONCLUSIONS

OATP1B1-mediated hepatic uptake of SN-38 was inhibited by uremic toxins, and gene expression of OATP1B1 was down-regulated by uremic plasma.

Optimization of cancer chemotherapy on the basis of pharmacokinetics and pharmacodynamics: from patients enrolled in clinical trials to those in the 'real world'

  Cytotoxic anticancer drugs are the most challenging therapeutic agents among all medicines with relatively narrow efficacy profiles. Therefore, medical oncologists have to practically manage the risk of severe toxic effects to optimize treatment outcomes. Dose and treatment-schedule recommendations for cytotoxic anticancer agents are determined on the basis of clinical trials. Patients enrolled in clinical trials are those likely to receive the drug in clinical practice, excluding those with conditions such as organ dysfunction, obesity, advanced age, or comorbidity. On the other hand, the 'real world' includes large numbers of such patients who do not meet the eligibility criteria of clinical trials. However, there is a paucity of data from sufficiently powered pharmacokinetic and pharmacodynamic studies to support dosage recommendations in such patients. Consequently, dose levels and treatment schedules for chemotherapy in these subjects are somewhat arbitrary and not evidence-based. Pharmacokinetic and pharmacodynamic studies of patients in the 'real world' are needed to address this issue. In this review article, we describe general aspects of clinical pharmacology in cancer patients enrolled in clinical trials and those in the 'real world,' and introduce recent findings regarding the pharmacokinetic and pharmacodynamic properties of irinotecan and S-1 in 'real world' cancer patients.

Predictors of irinotecan toxicity and efficacy in treatment of metastatic colorectal cancer

The colorectal cancer ranks high among the malignant tumours in incidence and mortality and irinotecan is standardly used in palliative treatment of metastatic disease in every therapeutic line. Unfortunately, the treatment with irinotecan is often associated with severe toxicities, especially neutropenia and diarrhea. The majority of the toxic manifestation is caused by the insufficient deactivation (glucuronidation) of irinotecan active metabolite SN-38 by UGT1A enzyme. The elevated SN-38 plasma concentration is responsible for the hematological and gastrointestinal toxicity that can become life-threatening. The patients carrying the mutation of the gene encoding UGT1A enzyme lack the ability of bilirubin glucuronidation, and suffer from the inherited un-conjugated hyperbilirubinemia (Gilbert syndrome, Crigler-Najjar type 1 and 2 syndrome). The mutations in other enzyme systems also play role in the etiopathogenesis of the irinotecan toxicity: CYP3A (cytochrome P-450), ABC family of transmembrane transporters (adenosine-triphosphate binding cassette). The goal of the contemporary research is to determine the predictive factors that will enable the individual adjustment of the individual drug dosage while minimising the adverse effects and maintaining the treatment benefit.

Concomitant polypharmacy is associated with irinotecan-related adverse drug reactions in patients with cancer

BACKGROUND

Patients with cancer often receive chemotherapeutic agents concurrently with other medications to treat comorbidity. The practical effects of concomitant medications, especially polypharmacy, on adverse drug reactions related to irinotecan-based chemotherapy are not well documented.

METHODS

Associations of adverse drug reactions related to irinotecan monotherapy or a combination of irinotecan, 5-fluorouracil, and L-leucovorin (FOLFIRI) with concomitant medicines used to treat comorbidity were retrospectively investigated in Japanese patients with cancer.

RESULTS

Of the 172 patients, 118 received concomitant medications. Twenty-one patients had grade 4 neutropenia and/or grade 3 or 4 diarrhea. Univariate and multivariate analyses revealed that concomitant medications were significantly associated with irinotecan-related severe neutropenia and/or diarrhea (P = 0.023 and 0.044). Multiple concomitant medications were significantly related to severe irinotecan-related toxicity in patients given monotherapy or FOLFIRI (P = 0.01). The incidence of severe irinotecan-related toxicities increased in parallel with the number of concomitant medications.

CONCLUSION

We found that multiple concomitant medicines were significantly associated with severe irinotecan-related toxicity, indicating that polypharmacy must be effectively managed to decrease the risk of adverse drug reactions in patients with cancer who received irinotecan-based chemotherapy.

Evaluation of current practice: management of chemotherapy-related toxicities

Adverse effects induced by cytotoxic chemotherapy (CT) have been mostly evaluated in clinical trials. The aim of this study was to assess in a nonselected patients group the incidence of CT-related toxicities and to identify risk factors in daily practice. Patients treated with CT (except cisplatin-based or carboplatin-based CT), for a solid tumour, were included in a prospective multicentre observational study. Clinical parameters, renal function and albumin level were assessed at baseline. Multivariate logistic regression was used to identify risk factors of CT-related toxicities. A total of 502 patients were recruited in different types of oncology departments. During CT, 62% of patients experienced grade 2-4 toxicities. Haematological toxicities affected 34% of patients and 20% of patients developed an infection requiring antibiotics. For 55% of patients, toxicities induced dose reduction (59% of cases), CT delay (25%) or discontinuation (16%) according to the management habits in the investigating centre. Performance status≥1, breast cancer, lymphopenia, hypoalbuminaemia and clearance creatinine<60 ml/min were risk factors for haematological toxicity. Performance status≥1, hypoalbuminaemia, proteinuria and clearance creatinine<90 ml/min were risk factors for change of CT schedule. A majority of patients receiving CT experienced significant toxicity leading to change of standard CT protocol. Albumin, creatinine clearance and lymphocyte should be routinely monitored at baseline to manage CT and to prevent their toxicities.

High-density real-time PCR-based in vivo toxicogenomic screen to predict organ-specific toxicity

Toxicogenomics, based on the temporal effects of drugs on gene expression, is able to predict toxic effects earlier than traditional technologies by analyzing changes in genomic biomarkers that could precede subsequent protein translation and initiation of histological organ damage. In the present study our objective was to extend in vivo toxicogenomic screening from analyzing one or a few tissues to multiple organs, including heart, kidney, brain, liver and spleen. Nanocapillary quantitative real-time PCR (QRT-PCR) was used in the study, due to its higher throughput, sensitivity and reproducibility, and larger dynamic range compared to DNA microarray technologies. Based on previous data, 56 gene markers were selected coding for proteins with different functions, such as proteins for acute phase response, inflammation, oxidative stress, metabolic processes, heat-shock response, cell cycle/apoptosis regulation and enzymes which are involved in detoxification. Some of the marker genes are specific to certain organs, and some of them are general indicators of toxicity in multiple organs. Utility of the nanocapillary QRT-PCR platform was demonstrated by screening different references, as well as discovery of drug-like compounds for their gene expression profiles in different organs of treated mice in an acute experiment. For each compound, 896 QRT-PCR were done: four organs were used from each of the treated four animals to monitor the relative expression of 56 genes. Based on expression data of the discovery gene set of toxicology biomarkers the cardio- and nephrotoxicity of doxorubicin and sulfasalazin, the hepato- and nephrotoxicity of rotenone, dihydrocoumarin and aniline, and the liver toxicity of 2,4-diaminotoluene could be confirmed. The acute heart and kidney toxicity of the active metabolite SN-38 from its less toxic prodrug, irinotecan could be differentiated, and two novel gene markers for hormone replacement therapy were identified, namely fabp4 and pparg, which were down-regulated by estradiol treatment.

Delayed elimination of SN-38 in cancer patients with severe renal failure

This prospective study is designed to examine the effects of severe renal failure on the pharmacokinetics of irinotecan. The pharmacokinetics of irinotecan, 7-ethyl-10-hydroxycamptothecin (SN-38), and SN-38 glucuronide (SN-38G) in three cancer patients with severe renal failure [creatinine clearance (Ccr) ≤ 20 ml/min] who were undergoing dialysis and received 100 mg/m(2) irinotecan as monotherapy were prospectively compared with those in five cancer patients with normal renal function (Ccr ≥ 60 ml/min). To ensure that the subjects had similar genetic backgrounds of UDP-glucuronosyltransferase (UGT) 1A1, patients with UGT1A1*1/*1, *1/*6, or *1/*28 were enrolled. The estimated terminal elimination rate constant of SN-38 in patients undergoing dialysis was approximately one tenth of that in patients with normal renal function (P = 0.025). Approximately 50% of SN-38 was dialyzed with a 2.1-m(2) dialysis membrane, whereas 27% was dialyzed with a 1.5-m(2) membrane. Our results showed that the elimination of SN-38 was significantly delayed in patients with severe renal failure compared with patients with normal renal function. We demonstrated that SN-38 was partly dialyzed.

Effects of mannose-binding lectin polymorphisms on irinotecan-induced febrile neutropenia

OBJECTIVE

Mannose-binding lectin (MBL) is important in the innate immune response. MBL2 gene polymorphisms affect MBL expression, and genotypes yielding low MBL levels have been associated with an elevated risk for infections in hematological cancer patients undergoing chemotherapy. However, these reported associations are inconsistent, and data on patients with solid tumors are lacking. Here, we investigated the effects of MBL2 genotypes on irinotecan-induced febrile neutropenia in patients with solid tumors.

PATIENTS AND METHODS

Irinotecan-treated patients were genotyped for the MBL2 gene. Two promoter (-550 H/L and -221 X/Y) and three exon polymorphisms (52 A/D, 54 A/B, and 57 A/C) were determined, together with known risk factors for irinotecan-induced toxicity. Neutropenia and febrile neutropenia were recorded during the first course.

RESULTS

Of the 133 patients, 28% experienced severe neutropenia and 10% experienced febrile neutropenia. No associations were found between exon polymorphisms and febrile neutropenia. However, patients with the H/H promoter genotype, associated with high MBL levels, experienced significantly more febrile neutropenia than patients with the H/L and L/L genotypes (20% versus 13% versus 5%). Moreover, patients with the HYA haplotype encountered significantly more febrile neutropenia than patients without this high MBL-producing haplotype (16% versus 4%). In the subgroup with wild-type exon polymorphisms (A/A), patients with the high MBL promoter phenotype had the highest incidence of febrile neutropenia, regardless of known risk factors.

CONCLUSION

Patients with high MBL2 promoter genotypes and haplotypes seem more at risk for developing febrile neutropenia. If confirmed, these preliminary findings may contribute to more individualized approaches of irinotecan treatment.

Irinotecan and its active metabolite, SN-38: review of bioanalytical methods and recent update from clinical pharmacology perspectives

The introduction of irinotecan has revolutionized the applicability of camptothecins as predominant topoisomerase I inhibitor for anti-cancer therapy. The potent anti-tumor activity of irinotecan is due to rapid formation of an in vivo active metabolite, SN-38. Therefore, irinotecan is considered as a pro-drug to generate SN-38. Over the past decade, side-by-side with the clinical advancement of the use of irinotecan in the oncology field, a plethora of bioanalytical methods have been published to quantify irinotecan, SN-38 and other metabolites. Because of the availability of HPLC, LC-MS and LC-MS/MS methods, the pharmacokinetic profiling of irinotecan and its metabolites has been accomplished in multiple species, including cancer patients. The developed assays continue to find use in the optimization of newly designed delivery systems with regard to pharmacokinetics to promote safe and effective use of either irinotecan or SN-38. This review intends to: firstly, provide an exhaustive compilation of the published assays for irinotecan, SN-38 and other metabolite(s) of irinotecan, as applicable; secondly, to enumerate the validation parameters and applicable conclusions; and thirdly, provide some recent perspectives in the clinical pharmacology arena pertaining to efflux transporters, pediatric profiling, role of kidney function in defining toxicity, drug-drug interaction potential of irinotecan, etc.

Treatment of childhood sarcoma with irinotecan: bilirubin level as a predictor of gastrointestinal toxicity

Irinotecan is a promising anticancer agent for the treatment of childhood cancer unresponsive to conventional chemotherapy. Its active metabolite, 7-ethyl-10 hydroxycamptothecin (SN-38) is glucuronidated by a uridine-diphosphoglucuronosyltransferase (UGT1A1) to form an inactive metabolite. It was supposed that patients with the UGT1A1*28 polymorphism would have a greater prevalence of elevated pretreatment serum bilirubin levels and higher toxicity. The aim of our study was to investigate the predictive value of pre-treatment bilirubin levels in the development of severe diarrhea in solid tumor patients treated with irinotecan. The survey included 14 pediatric patients with refractory sarcomas treated with irinotecan (CPT-11). Patients were grouped based on the development of mild (G0-2) or severe (G3) gastrointestinal toxicity. The simple linear regression model and the non-parametric paired wilcoxon test were adopted for the analysis. p <0.05 was judged to indicate a significant difference. The results showed a significant increase in severity of diarrhea with increasing total pre-treatment bilirubin. therefore, we propose that pre-treatment bilirubin levels can predict gastrointestinal toxicity in pediatric cancer.

Additive effects of drug transporter genetic polymorphisms on irinotecan pharmacokinetics/pharmacodynamics in Japanese cancer patients

PURPOSE

Effects of genetic polymorphisms/variations of ABCB1, ABCC2, ABCG2 and SLCO1B1 in addition to "UGT1A1*28 or *6" on irinotecan pharmacokinetics/pharmacodynamics in Japanese cancer patients were investigated.

METHODS

Associations between transporter haplotypes/variations along with UGT1A1*28 or *6 and SN-38 area under the time-concentration curve (AUC) or neutropenia were examined in irinotecan monotherapy (55 patients) and irinotecan-cisplatin-combination therapy (62 patients).

RESULTS

Higher SN-38 AUC values were observed in ABCB1 2677G>T (A893S) (*2 group) for both regimens. Associations of grade 3/4 neutropenia were observed with ABCC2 -1774delG (*1A), ABCG2 421C>A (Q141K) and IVS12 + 49G>T ((#) IIB) and SLCO1B1 521T>C (V174A) (*15 x 17) in the irinotecan monotherapy, while they were evident only in homozygotes of ABCB1*2, ABCG2 (#) IIB, SLCO1B1*15 x 17 in the cisplatin-combination therapy. With combinations of haplotypes/variations of two or more genes, neutropenia incidence increased, but their prediction power for grade 3/4 neutropenia is still unsatisfactory.

CONCLUSIONS

Certain transporter genotypes additively increased irinotecan-induced neutropenia, but their clinical importance should be further elucidated.

Irinotecan in Cancer Patients with End-Stage Renal Failure

Objective:

To observe and report on the pharmacokinetics of irinotecan in a patient with end-stage renal failure (ESRF) who was undergoing hemodialysis.

Case Summary:

A 64-year-old man with metastatic colorectal cancer who was on hemodialysis was treated with Irinotecan 50 mg/m2 weekly for 3 weeks, followed by 1 week with no treatment. As the drug was well tolerated, the dosage was increased to 80 mg/m2 after 2 cycles. Diagnostic testing of a hepatic lesion after 2 and 6 treatment cycles showed stable disease. The carcinoembryonic antigen value decreased to 40% of its pretreatment level. Pharmacokinetically, our patient had a lower apparent clearance and a higher maximum concentration of the active metabolite SN-38 (130 L/h/m2, maximum concentration 0.4 μg/L per mg of irinotecan) compared with published values from patients with normal renal function. Removal of irinotecan and its metabolites by hemodialysis was negligible.

Discussion:

The reason for the unexpectedly low clearance of SN-38 in our patient remains unclear. We speculate that inhibition of the OATP1B1 transporter by uremic toxins could be an explanation. Such a mechanism would explain excessive irinotecan toxicity, as reported in previous case reports of patients undergoing hemodialysis.

Conclusions:

We conclude that approximately two-thirds of the standard weekly irinotecan dosage regimen should be considered in patients with ESRF.