Use of etoposide in patients with organ dysfunction: pharmacokinetic and pharmacodynamic considerations

Case Report: Rapid Recognition and Immune Modulation of Secondary HLH Due to Disseminated HSV Infection

We describe the case of a newborn who presented with multiple organ dysfunction syndrome (MODS) and hyperferritinemia, who eventually met criteria for hemophagocytic lymphohistiocytosis (HLH) due to disseminated herpes simplex virus 1 (HSV-1). While the cytokine storm abated after administration of multiple immune modulatory therapies including dexamethasone, etoposide, intravenous immune globulin, anakinra, as well as the interferon gamma antagonist emapalumab, multiple organ dysfunction syndrome progressed. Care was withdrawn after 5 days. Subsequent genetic testing did not reveal any mutations associated with familial HLH. This case highlights that even with appropriate antiviral treatment and immune suppression, disseminated HSV is often fatal. Further study is warranted to determine whether early immune modulatory therapy including interferon gamma blockade can interrupt the HLH inflammatory cascade and prevent progression of MODS.

Etoposide dosage adjustment in two patients with neuroendocrine tumors and severe liver impairment

Introduction

Limited data are available on dosing etoposide in patients with liver impairment.

Case report

We report the dosing strategies for etoposide utilized in two patients with neuroendocrine tumors and severe liver impairment.

Management and outcomes

Treatment consisted of platinum-based chemotherapy regimens, with the decision of whether to administer etoposide and at what doses being based on the liver function before each chemotherapy cycle. By the end of treatment, total bilirubin was normal, and the performance status of both patients had improved, with stable computed tomography scan findings.

Discussion

The reported two cases suggest that the administration of etoposide at reduced doses with close monitoring in patients with neuroendocrine tumors and severe liver impairment may still be considered as an option and may improve outcomes.

A guide to clinically relevant drug interactions in oncology

This paper presents an overview of new information on clinically relevant drug-drug interactions, particular focuses on negative drug interactions in oncology. We have generated a concise table of drug-drug interactions that provides a synopsis of the clinical outcome of the interaction along with a recommendation for management. We have also generated other tables that describe specific interactions with methotrexate and dosing guidelines for cytotoxic drugs in the presence of renal or hepatic dysfunction. Since warfarin is one of the non-anticancer drugs that is commonly used in cancer patients for the treatment and prevention of venous thromboembolism, its interactions with other anticancer drugs that have been reported in literatures were also reviewed in this paper. In general, drug interactions observed in cancer patients may be categorized into pharmacokinetic, pharmacodynamic and pharmaceutic interactions. Pharmacokinetic interactions involve one drug altering the absorption, distribution, metabolism, or excretion of another drug. Interpatient variability in the pharmacokinetic profile of many anticancer agents often complicates the predictability of the antitumor response and toxicities. Among four pharmacokinetic characteristics, drug interactions involving hepatic metabolism is probably the most common and important mechanism responsible for oncologic drug interactions. For example, several anticancer drugs including taxanes, vinca alkaloids, and irinotecan are known to be metabolized by cytochrome CYP3A4. Enzyme-inducing anticonvulsants have been shown to significantly decrease the plasma levels of these anticancer drugs, thereby compromising the anti-tumor effects. N ephrotoxicity or changes in hepatic function caused by some anticancer drugs (e.g., cisplatin, asparaginase) may also have an impact on the pharmacokinetics of the interacting agents. Pharmacodynamic interactions may occur when two or more drugs acting at a common receptor-binding site impact on the pharmacologic action of the object drug, without influencing the pharmacokinetics of each interacting agent. In clinical setting, a decrease of antitumor efficacy was observed in breast cell lines when gemcitabine or vinorelbine were used in combination with paclitaxel. On the other hand, a decreased incidence of thrombocytopenia was seen in patients receiving combination of carboplatin and palcitaxel compared to those receiving carboplatin alone. The third type of drug-drug interaction is known as pharmaceutic interaction. When one drug may alter the physical or chemical compatibility of another drug that utlimately leads to a change in appearance of the solution or a decrease of effectiveness of the drug due to drug inactivation or degradation.

How I treat acute myeloid leukemia presenting with preexisting comorbidities

Acute myeloid leukemia (AML) is a devastating disease with an incidence that progressively increases with advancing age. Currently, only ∼40% of younger and 10% of older adults are long-term survivors. If untreated, the overall prognosis of AML remains dismal. Initiation of therapy at diagnosis is usually urgent. Barriers to successful therapy for AML are the attendant toxicities directly related to chemotherapy or those associated with inevitable aplasia. Organ dysfunction often further complicates such toxicities and may even be prohibitive. There are few guidelines to manage such patients and the fear of crossing the medico-legal abyss may dominate. Such clinical scenarios provide particular challenges and require experience for optimal management. Herein, we discuss select examples of common pretreatment comorbidities, including cardiomyopathy, ischemic heart disease; chronic renal failure, with and without dialysis; hepatitis and cirrhosis; chronic pulmonary insufficiency; and cerebral vascular disease. These comorbidities usually render patients ineligible for clinical trials and enormous uncertainty regarding management reigns, often to the point of withholding definitive therapy. The scenarios described herein emphasize that with appropriate subspecialty support, many AML patients with comorbidities can undergo therapy with curative intent and achieve successful long-term outcome.

Antimicrobial dosing in acute renal replacement

Acute kidney injury (AKI) is a common problem in hospitalized patients and is associated with significant morbidity and mortality. Two large trials showed no benefit from increased doses of renal replacement therapy (RRT) despite previous clinical data suggesting that increased clearance from RRT has beneficial effects. Since infection is the leading cause of death in AKI, my group and others hypothesized that increased RRT antibiotic clearance might create a competing morbidity. The data from my group, as well as those of other groups, show that many patients are underdosed when routine "1 size fits all" antibiotic dosing is used in patients with AKI receiving continuous RRT (CRRT). Here, concepts of drug distribution and clearance in AKI are briefly discussed and then 1 antibiotic (piperacillin) is discussed in depth to illustrate the challenges in applying the medical literature to clinical practice. The fact that published data on drug dosing in AKI and dialysis reflect the evolution of practice patterns and often do not apply to present prescribing habits is also discussed. A more general approach to drug dosing facilitates situation-specific prescribing by the nephrologist and critical care specialist.

Jaundice as a presenting manifestation of pediatric non-Hodgkin lymphoma: etiology, management, and outcome

OBJECTIVES

There are few data available on the management and outcome of pediatric patients with non-Hodgkin lymphoma (NHL) presenting with jaundice. Controversies exist on biliary drainage and chemotherapy dose modifications to be carried out in such patients. The aim of this study was to analyze the causes of jaundice in, the various modalities of treatment administered to, and outcome of patients aged 18 years or less, with de novo NHL and jaundice treated at our center.

PATIENTS AND METHODS

A retrospective analysis show 9 such cases (11.2% of all NHL cases), all of whom were treated by a uniform protocol. Chemotherapy dose modifications were based on serum bilirubin and clinical status of the patients.

RESULTS

Obstructive jaundice was the most common cause (7 of 9). Seven patients achieved normal serum bilirubin with chemotherapy alone. Only one had a biliary drainage procedure. Four patients were alive and disease-free at last follow-up.

CONCLUSIONS

Although biliary obstruction is the commonest most cause of jaundice in pediatric and adolescent NHL, biliary drainage may be unnecessary and chemotherapy alone may suffice as initial treatment for these patients.

Commentary: Oncologic drugs in patients with organ dysfunction: a summary

There are few prospective data regarding the pharmacokinetics and clinical toxicity of commonly used chemotherapeutics in cancer patients with organ dysfunction. Although increasing numbers of studies are investigating newer chemotherapeutics in patients with liver or kidney dysfunction, most guidelines for dosing, especially for established agents, remain empiric. This review describes the available data (both prospective and case study) evaluating the impact of renal and hepatic dysfunction on toxicity and dosing of commonly used chemotherapeutics and provides a practical summary for their use in this setting.

A phase I trial defining the maximum tolerated systemic exposure of topotecan in combination with Carboplatin and Etoposide in extensive stage small cell lung cancer

PURPOSE

Topotecan is active in relapsed small cell lung cancer; thus, its addition to the standard carboplatin-etoposide regimen may improve outcomes in extensive-stage small cell lung cancer (ES-SCLC) patients. Significant interpatient variability in the topotecan systemic exposure results when it is dosed based on body surface area (mg/m2). The purpose of this Phase I trial was to determine the maximally tolerated systemic exposure (MTSE) of topotecan in combination with carboplatin and etoposide.

METHODS

Thirty-four chemotherapy-naïve ES-SCLC patients received topotecan in combination with carboplatin AUC 5 mg/mL*min and oral etoposide 100 mg/m2/day. Topotecan was administered as a 30-minute infusion either on Days 1-5 or Days 1-3 and the dosage was individualized to attain a topotecan lactone AUC range (ng/mL*hr) in successive patient cohorts from 7 to 23; 24 to 36; 37 to 53; 54 to 66.

RESULTS

The majority (67 percent) of the measured topotecan AUCs were within target range. Overall, 8 of 34 patients experienced Cycle 1 dose-limiting toxicity (DLT), either neutropenia or thrombocytopenia. Carboplatin administration prior to topotecan resulted in 2 of 6 patients having Cycle 1 DLT. When the administration sequence was changed (topotecan, carboplatin, etoposide), Cycle 1 hematologic toxicity decreased; however, the maximum topotecan lactone AUC of 24-36 ng/mL*hr (median dose 0.82 mg/m2) had significant cumulative hematologic toxicity. The number of topotecan doses were reduced from 5 to 3, which resulted in a maximum topotecan lactone AUC of 37 to 53 ng/mL*hr with only 1 of 6 patients having Cycle 1 DLT. Overall response rate was 71 percent with median survival of 10.8 months.

CONCLUSION

It is feasible to target topotecan lactone AUC in adult ES-SCLC patients. However, this triplet regimen resulted in considerable hematologic toxicity and has a median survival comparable to carboplatin-etoposide. Alternative, less toxic regimens should be investigated for improving survival in ES-SCLC.

Glucuronidation of etoposide in human liver microsomes is specifically catalyzed by UDP-glucuronosyltransferase 1A1

A metabolite formed by incubation of human liver microsomes, etoposide, and UDP-glucuronic acid was identified as etoposide glucuronide by liquid chromatography-tandem mass spectrometry analysis. According to the derivatization with trimethylsilylimidazole (Tri-Sil-Z), it was confirmed that the glucuronic acid is linked to an alcoholic hydroxyl group of etoposide and not to a phenolic group. Among nine recombinant human UGT isoforms (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A8, UGT1A9. UGT1A10, UGT2B7, and UGT2B15), only UGT1A1 exhibited the catalytic activity of etoposide glucuronidation. The enzyme kinetics in pooled human liver microsomes and recombinant UGT1A1 microsomes showed a typical Michaelis-Menten plot. The kinetic parameters of etoposide glucuronidation were K(m) = 439.6 +/- 70.7 microM and V(max) = 255.6 +/- 19.2 pmol/min/mg of protein in human liver microsomes and K(m) = 503.2 +/- 110.2 microM and V(max) = was 266.5 +/- 28.6 pmol/min/mg of protein in recombinant UGT1A1. The etoposide glucuronidation in pooled human liver microsomes was inhibited by bilirubin (IC(50) = 31.7 microM) and estradiol (IC(50) = 34 microM) as typical substrates for UGT1A1. The inhibitory effects of 4-nitrophenol (IC(50) = 121.0 microM) as a typical substrate for UGT1A6 and UGT1A9, imipramine (IC(50) = 393.8 microM) as a typical substrate for UGT1A3 and UGT1A4, and morphine (IC(50) = 109.3 microM) as a typical substrate for UGT2B7 were relatively weak. The interindividual difference in etoposide glucuronidation in 13 human liver microsomes was 78.5-fold (1.4-109.9 pmol/min/mg of protein). The etoposide glucuronidation in 10 to 13 human liver microsomes was significantly correlated with beta-estradiol-3-glucuronidation (r = 0.841, p < 0.01), bilirubin glucuronidation (r = 0.935, p < 0.01), and the immunoquantified UGT1A1 protein content (r = 0.800, p < 0.01). These results demonstrate that etoposide glucuronidation in human liver microsomes is specifically catalyzed by UGT1A1.

Toxicity patterns of cytotoxic drugs

Toxicity is a major concern for anticancer drugs. These compounds present a narrow therapeutic index, with a small difference between the dose required for an antitumor effect and that responsible for unacceptable toxicity. Their recommended doses are determined according to the toxicity endpoint. Moreover, toxicity is observed earlier than the therapeutic effect, so, toxic effects represent a major endpoint for pharmacodynamic studies of cytotoxic drugs. Knowledge of toxicity patterns and main factors of toxicity of anticancer drugs is required before modeling data of these studies. Hematological toxicities represent the main toxicity of the cytotoxic. However, non-hematological toxicities have become more important than hematological toxicities as pharmacodynamic endpoints in some circumstances such as high-dose chemotherapy associated with bone marrow transplantation. This paper will describe the main toxicity of the cytotoxic drugs, and its factors of both inter- and intra-patient variability. The toxicity pattern of topotecan will be examined as an example. Knowledge of the toxicity pattern of a drug constitutes a prerequirement before modeling its pharmacodynamics.

Feasibility of combination chemotherapy with cisplatin and etoposide for haemodialysis patients with lung cancer

Cancer chemotherapy for haemodialysis patients has never been established. To elucidate the feasibility of cisplatin-based combination chemotherapy for haemodialysis patients with lung cancer, a dose escalation study was conducted. Five haemodialysis patients with lung cancer were treated with cisplatin and etoposide. A starting dose of 40 mg m(-2) of cisplatin on day 1 and 50 mg m(-2) of etoposide on days 1, 3 and 5 were administered as the first course for the first patient. Membrane haemodialysis was regularly performed three times a week and soon after the completion of therapy. By monitoring toxicity and pharmacokinetics data, the dose was escalated course by course and patient by patient. Dose escalation was completed for the first two patients resulting in full-dose chemotherapy consisting of 80 mg m(-2) of cisplatin on day 1 and 100 mg m(-2) of etoposide on days 1, 3 and 5. Multiple courses of the full-dose chemotherapy were administered to the other three patients. Toxicity was manageable and tolerable for all. Pharmacokinetics data were comparable to those from patients with normal renal function, except for potential long-lasting higher levels of free platinum in the renal insufficiency group. In conclusion, this standard-dose combination chemotherapy was feasible even for haemodialysis patients.

Randomized cross-over clinical trial to study potential pharmacokinetic interactions between cisplatin or carboplatin and etoposide

AIMS

Cisplatin and carboplatin are often used in combination with etoposide. In a randomized cross-over study, the potential interaction between the two platinum drugs and the metabolism of etoposide was explored. In vitro investigations using human liver microsomes were also performed.

METHODS

Etoposide was administered to 15 patients over 3 days, with the platinum drug administered on day 2. The alternate platinum drug was administered on the second course. The pharmacokinetics of etoposide were determined on all 3 days of each cycle. The effect of platinum drugs on etoposide metabolism by human liver enzymes was explored in vitro.

RESULTS

Neither cisplatin nor carboplatin coadministration affected the pharmacokinetics of etoposide during cycle 1. When carboplatin was administered on course 2, etoposide AUC was 8% higher on day 2 compared with day 1 or day 3 (for day 2 vs day 3, 95% CI: -0.72, -0.08 mg ml(-1) min). In contrast, cisplatin on course 2 increased the AUC of etoposide (28%) on day 3 (day 3 vs day 1, 95% CI: 0.67, 2.09 mg ml(-1) min), with no effect on day 2. In vitro carboplatin and cisplatin (10-100 microm) inhibited the metabolism of etoposide, if rat liver microsomes were preincubated (30 min) with NADPH and the platinum complexes. With human liver microsomes a small effect on etoposide metabolism, but not on catechol formation, was observed.

CONCLUSIONS

The interaction between etoposide and platinum drugs is small and, given the pharmacokinetic variability seen with etoposide, the clinical impact is unlikely to be significant.

Optimizing drug regimens in cancer chemotherapy by an efficacy-toxicity mathematical model

In cancer chemotherapy, it is important to design treatment strategies that ensure a desired rate of tumor cell kill without unacceptable toxicity. To optimize treatment, we used a mathematical model describing the pharmacokinetics of anticancer drugs, antitumor efficacy, and drug toxicity. This model was associated with constraints on the allowed plasma concentrations, drug exposure, and leukopenia. Given a schedule of drug administrations, the mathematical model optimized the drug doses that can minimize the tumor burden while limiting toxicity at the level of the white blood cells. The main result is that the optimal drug administration is an initial high-dose chemotherapy up to saturation of constraints associated with normal cell toxicity and a maintenance continuous infusion at a moderate rate. Data related to etoposide investigations were used in a feasibility study. Simulations with the optimized protocol showed better performances than usual clinical protocols. Model-based optimal drug doses provide for greater cytoreduction, while limiting the risk of unacceptable toxicity.