Suspected ifosfamide-induced neurotoxicity

The safety of current pharmacotherapeutic strategies for osteosarcoma

Introduction: Peri-operative chemotherapy is the backbone of treatment for patients with osteosarcoma. Methotrexate, cisplatinum, doxorubicin and ifosfamide are the main drugs used in chemotherapy regimens used for osteosarcoma.Areas covered: We have reviewed here the relevant literature related to the incidence and management of acute and late toxicities of systemic treatment used for the management of patients with osteosarcoma.Expert opinion: Early diagnosis and appropriate management of acute and late toxicities of chemotherapy is crucial for an efficient care of osteosarcoma patients. Although the incidence and management of chemotherapy-related acute toxicities are well known by most oncologists, the use of high doses of methotrexate have the potential to cause fatal toxicities and, therefore, needs careful monitoring. Moreover, the diagnosis of late toxicities is more challenging and requires long-term follow-up for an appropriate management.

Neurotoxicity of antineoplastic drugs: Mechanisms, susceptibility, and neuroprotective strategies

This review summarizes the adverse effects on the central and/or peripheral nervous systems that may occur in response to antineoplastic drugs. In particular, we describe the neurotoxic side effects of the most commonly used drugs, such as platinum compounds, doxorubicin, ifosfamide, 5-fluorouracil, vinca alkaloids, taxanes, methotrexate, bortezomib and thalidomide. Neurotoxicity may result from direct action of compounds on the nervous system or from metabolic alterations produced indirectly by these drugs, and either the central nervous system or the peripheral nervous system, or both, may be affected. The incidence and severity of neurotoxicity are principally related to the dose, to the duration of treatment, and to the dose intensity, though other factors, such as age, concurrent pathologies, and genetic predisposition may enhance the occurrence of side effects. To avoid or reduce the onset and severity of these neurotoxic effects, the use of neuroprotective compounds and/or strategies may be helpful, thereby enhancing the therapeutic effectiveness of antineoplastic drug.

Methylene Blue for Management of Ifosfamide-Induced Encephalopathy

Objective:

To evaluate the use of methylene blue for the treatment of ifosfamide-induced encephalopathy.

Data Sources:

MEDLINE (1966–August 2005) and International Pharmaceutical Abstracts (1971–August 2005) were searched, using the terms methylene blue, ifosfamide, encephalopathy, and neurotoxicity.

Data Synthesis:

Several case reports and one retrospective chart review described the use of methylene blue for ifosfamide-induced encephalopathy, but no controlled clinical trials were found. Methylene blue appeared to aid in the resolution of encephalopathic symptoms as rapidly as within 10 minutes of administration in some patients, but it had modest efficacy in most patients. Symptoms in patients who did not receive methylene blue resolved in the same time frame; this indicates that ifosfamide-induced encephalopathy may resolve without treatment.

Conclusions:

Available data from case reports indicate that methylene blue is an option in the treatment of ifosfamide-induced encephalopathy, especially in patients with severe symptoms of toxicity. However, the lack of controlled clinical trials and the possibility of spontaneous resolution of encephalopathy make the usefulness of methylene blue unclear.

Novel treatment for the management of ifosfamide neurotoxicity: Rationale for the use of methylene blue

Objective. To provide an overview of the proposed pathophysiology of ifosfamide encephalopathy and the role of methylene blue for the treatment and prevention of this toxicity.

Data Source. A Medline search using the terms ‘‘ifosfamide encephalopathy’’ and ‘‘methylene blue’’ was conducted for the period of 1990-2001. The reference lists from retrieved articles were reviewed

Data Extraction. The author reviewed the retrieved material and included animal and pharmacokinetic data related to ifosfamide and the pathophysiology of ifosfamide neurotoxicity. Additionally, preclinical data and case reports describing the clinical use and rationale for methylene blue were included.

Data Synthesis. Encephalopathy is a unique toxicity described with ifosfamide, but not with cyclophosphamide. Ifosfamide undergoes a secondary ‘‘deactivation’’ metabolic pathway to yield dechloroethylated metabolites and chloroacetalde-hyde. Chloroacetaldehyde is a metabolite that contributes to both the nephrotoxicity and neurotoxicity described with ifosfamide. Chloroacetaldehyde (or a dechloroethylated metabolite) may exert neurotoxic effects by one or more of the following mechanisms: (a) direct neurotoxic damage, (b) depletion of central nervous system (CNS) glutathione level, or (c) inhibition of mitochondrial oxidative phosphorylation resulting in impaired fatty acid metabolism. The biochemical derangements described with this acute toxicity appear to mimic a neonatal mitochondrial disorder, for which methylene blue has been used. Methylene blue has been shown to restore and maintain mitochondrial respiration and therefore can be used to correct or prevent acute neurotoxic effects. Methylene blue has been used to treat moderate to severe cases of ifosfamide neurotoxicity and has also been used prophylactically to prevent encephalopathy in high-risk conditions with the use of oral and bolus iv ifosfamide regimens. Methylene blue may be useful in the treatment of grade III or IV neurotoxicity or in those patients with recurrent neurological symptoms associated with ifosfamide administration. The use of prophylactic or concurrent administration of methylene blue with ifosfamide requires further clinical evaluation.

Fatal Ifosfamide-induced metabolic encephalopathy in patients with recurrent epithelial ovarian cancer: report of two cases

Central nervous system (CNS) toxicity has been reported in approximately 10-30% of patients receiving intravenous infusions of ifosfamide. Encephalopathy is a rare but serious CNS adverse reaction in these patients, and although usually transient and reversible, may cause persistent neurological dysfunction or death. Clinical features range from fatigue and confusion to coma and death. Although methylene blue can be used to treat ifosfamide-induced neurotoxicity, including encephalopathy, its mechanism of action remains poorly defined. We describe here two patients with recurrent epithelial ovarian cancer who experienced fatal encephalopathy following ifosfamide/mesna treatment.

Evaluation of methylene blue, thiamine, and/or albumin in the prevention of ifosfamide-related neurotoxicity

SUMMARY

A serious adverse effect that can limit the utility of ifosfamide is neurotoxicity, known as ifosfamide-induced encephalopathy (IIE). Information regarding the usefulness of prophylactic administration of methylene blue, thiamine, and albumin to reduce the incidence of IIE is scarce. We present the results of a retrospective chart review evaluating the incidence of IIE in adult patients who received ifosfamide to treat sarcoma at the University of Washington within a 2-year period. Patients who received methylene blue, thiamine, and/or albumin were compared to patients who did not receive these prophylactic agents concurrently with ifosfamide. The primary objective was to evaluate if prophylaxis is associated with a reduced incidence of IIE. Identifying risk factors associated with IIE was a secondary objective. The cost of using prophylaxis with ifosfamide administration was reviewed.

RESULTS

A total of 166 cycles were included. For the primary endpoint, more cycles in the prophylaxis group had patients with symptoms of IIE (21.1% in the prophylaxis group vs. 8.4% in the nonprophylaxis group); p =0.026. The average number of risk factors per cycle was the same in each group; however, the type of risk factors differed.

CONCLUSIONS

Prophylaxis was not associated with a reduced incidence of IIE, and it does not appear to delay time to onset of symptoms at our institution.

RESULT

of this study provide no support for using methylene blue, thiamine, and/or albumin as routine prophylaxis when administering ifosfamide to adults with sarcoma.

Ifosfamide Encephalopathy

Encephalopathy is a potentially fatal toxicity of ifosfamide. Clinical manifestations of encephalopathy range from fatigue and confusion to coma and death. Early identification of this toxicity and prompt cessation of ifosfamide are the essential elements in the management of ifosfamide encephalopathy. Accurate prediction of this toxicity is often difficult. Based on the limited available evidence, methylene blue, an electron acceptor, may have a role in the treatment and the prevention of neurotoxicity. This paper reviews the current understanding of ifosfamide encephalopathy.

Sulfonyl-Containing Aldophosphamide Analogues as Novel Anticancer Prodrugs Targeted against Cyclophosphamide-Resistant Tumor Cell Lines

A series of sulfonyl-group containing analogues of aldophosphamide (Aldo) were synthesized as potential anticancer prodrugs that liberate the cytotoxic phosphoramide mustards (PM, IPM, and tetrakis-PM) via beta-elimination, a nonenzymatic activation mechanism. Kinetic studies demonstrated that all these compounds spontaneously liberate phosphoramide mustards with half-lives in the range of 0.08-15.2 h under model physiological conditions in 0.08 M phosphate buffer at pH 7.4 and 37 degrees C. Analogous to Aldo, the rates of beta-elimination in all compounds was enhanced in reconstituted human plasma under same conditions. The compounds were more potent than the corresponding phosphoramide mustards against V-79 Chinese hamster lung fibroblasts in vitro (IC(50) = 1.8-69.1 microM). Several compounds showed excellent in vivo antitumor activity in CD2F1 mice against both P388/0 (Wild) and P388/CPA (CP-resistant) tumor cell lines.

Role of nucleotide- and base-excision repair in genotoxin-induced neuronal cell death

Base-excision (BER) and nucleotide-excision (NER) repair play pivotal roles in protecting the genomes of dividing cells from damage by endogenous and exogenous agents (i.e. environmental genotoxins). However, their role in protecting the genome of post-mitotic neuronal cells from genotoxin-induced damage is less clear. The present study examines the role of the BER enzyme 3-alkyladenine DNA glycosylase (AAG) and the NER protein xeroderma pigmentosum group A (XPA) in protecting cerebellar neurons and astrocytes from chloroacetaldehyde (CAA) or the alkylating agent 3-methyllexitropsin (Me-Lex), which produce ethenobases or 3-methyladenine (3-MeA), respectively. Neuronal and astrocyte cell cultures prepared from the cerebellum of wild type (C57BL/6) mice or Aag(-/-) or Xpa(-/-) mice were treated with 0.1-50 microM CAA for 24h to 7 days and examined for cell viability, DNA fragmentation (TUNEL labeling), nuclear changes, and glutathione levels. Aag(-/-) neurons were more sensitive to the acute (>20 microM) and long-term (>5 microM) effects of CAA than comparably treated wild type neurons and this sensitivity correlated with the extent of DNA fragmentation and nuclear changes. Aag(-/-) neurons were also sensitive to Me-Lex at comparable concentrations of CAA. In contrast, Xpa(-/-) neurons were more sensitive than either wild type or Aag(-/-) neurons to CAA (>10 microM), but less sensitive than Aag(-/-) neurons to Me-Lex. Astrocytes from the cerebellum of wild type, Aag(-/-) or Xpa(-/-) mice were essentially insensitive to CAA at the concentrations tested. These studies demonstrate that BER and NER are required to protect neurons from genotoxin-induced cell death.