Effect of alpha lipoic acid on ifosfamide-induced central neurotoxicity in rats.

Ifosfamide (IFOS) which is a cytotoxic alkylating agent may cause central nervous system toxicity. Alpha-lipoic acid (ALA) has a strong antioxidant effects. We hypothesized that ALA could attenuate on ifosfamide-induced central neurotoxicity in rats. Rats were divided into Control, IFOS, ALA and IFOS+ALA groups. The toxic effects of IFOS were analyzed by oxidative parameters and caspase 3 immunohistochemical examinations of brain tissue. The catalase activity of IFOS group significantly reduced in comparison with control groups (p < 0.05). The malondialdehyde (MDA) level and protein carbonyl (PC) content in brain tissue were significantly higher in IFOS group than in the other groups (p < 0.05). ALA treatments significantly prevented the increase in MDA level (p < 0.001) and PC content (p < 0.05) in brain tissue. IFOS group showed profound activation of caspase 3. The control, ALA and IFOS+ALA groups did not show caspase 3 activation. It was concluded that ALA treatments may have beneficial effects protecting neurons from central neurotoxicity caused by IFOS.

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.

Amifostine and glutathione prevent ifosfamide- and acrolein-induced hemorrhagic cystitis.

INTRODUCTION: Ifosfamide (IFS) is an antineoplastic alkylating agent whose major side effect is hemorrhagic cystitis (HC). This toxicity is attributed to the renal excretion of acrolein (ACR), a highly urotoxic IFS metabolite. Despite the clinical use of mesna to prevent HC, a significant percent ( approximately 33%) of patients present with at last one feature of HC, mainly hematuria. AIM: To investigate the use of two antioxidants-amifostine and glutathione-for the prevention of experimental IFS- and ACR-induced HC. MATERIALS AND METHODS: Male Swiss mice were treated intraperitoneal (i.p.) with saline (control), glutathione (125, 250 or 500 mg/kg) or amifostine (25, 50 or 100 mg/kg), and 30 min later they received a single i.p. injection of IFS at a dose of 400 mg/kg. To investigate the systemic effects of the antioxidants on ACR-induced HC, the animals were treated with saline, amifostine (50 mg/kg, i.p.) or glutathione (500 mg/kg, i.p.), and 30 min afterward with 75 mug ACR intravesically (i.ve.). In another set of experiments, the antioxidants were injected directly into the bladder, where the mice received a single i.ve injection of ACR (75 mug) plus amifostine (1.5 mg/kg) or glutathione (2 mg/kg). HC was measured 3 h after IFS or ACR injection according to bladder wet weight, macroscopic (edema and hemorrhage) and microscopic changes, i.e., edema, hemorrhage, cellular infiltration, fibrin deposition and urothelial desquamation. RESULTS: Pretreatments with amifostine or glutathione prevented IFS-induced HC in a dose-dependent manner. Furthermore, ACR-induced HC was also prevented by systemic (i.p.) or local (i.ve.) pretreatment with glutathione or amifostine. The greatest protective effect was seen with local amifostine treatment (2 mg/kg i.ve.) (P < 0.05). CONCLUSIONS: Glutathione and amifostine show a beneficial effect in experimental IFS- and ACR-induced HC. Thus, they should be investigated as an alternative treatment to prevent HC observed in patients undergoing IFS treatment.

Comparative toxicity of ifosfamide metabolites and protective effect of mesna and amifostine in cultured renal tubule cells.

Renal injury is a common side effect of the chemotherapeutic agent ifosfamide. Current evidence suggests that the ifosfamide metabolite chloroacetaldehyde contributes to this nephrotoxicity. The present study examined the effects of chloroacetaldehyde and acrolein, another ifosfamide metabolite, on rabbit proximal renal tubule cells in primary culture. The ability of the uroprotectant medications sodium 2-mercaptoethanesulfonate (mesna) and amifostine to prevent chloroacetaldehyde- and acrolein-induced renal cell injury was also assessed. Chloroacetaldehyde and acrolein (25-200 M) produced dose-dependent declines in neutral red dye uptake, glucose transport and glutathione content. Chloroacetaldehyde was a more potent toxin than acrolein. Pretreatment of cells with the glutathione-depleting agent buthionine sulfoximine enhanced the toxicity of both chloroacetaldehyde and acrolein while co-administration of mesna or amifostine prevented metabolite toxicity. These results support the hypothesis that chloroacetaldehyde is responsible for ifosfamide-induced nephrotoxicity. The protective effect of mesna and amifostine in vitro contrasts with clinical experience showing that these medications do not eliminate ifosfamide nephrotoxicity.

Thymoquinone attenuates ifosfamide-induced Fanconi syndrome in rats and enhances its antitumor activity in mice.

The effect of thymoquinone (TQ), the main constituent of the Nigella sativa L. oil, on ifosfamide (IFO)-induced Fanconi syndrome (FS) and its antitumor activity were investigated in rats and mice, respectively. In rats, a daily injection of IFO (50 mg/kg per day, i.p.) for 5 days induced a FS characterized by wasting off glucose, electrolytes and organic acids, along with elevated serum creatinine and urea, as well as decreased creatinine clearance rate. Administration of TQ with the drinking water of rats, (5 mg/kg per day) for 5 days before and during IFO treatment, ameliorated the severity of IFO-induced renal damage. TQ significantly improved IFO-induced phosphaturia, glucosuria, elevated serum creatinine and urea, and significantly normalized creatinine clearance rate. Moreover, TQ significantly prevented IFO-induced renal glutathione (GSH) depletion and lipid peroxide accumulation. In mice bearing Ehrlich ascites carcinoma (EAC) xenograft, TQ (10 mg/kg per day) administered in drinking water significantly enhanced the antitumor effect of IFO (50 mg/kg per day, i.p. on days 1-4 and 15-18). Furthermore, mice treated with IFO in combination with TQ showed less body weight loss and mortality rate compared to IFO single therapy. These observations demonstrate that TQ may improve the therapeutic efficacy of IFO by decreasing IFO-induced nephrotoxicity and improving its antitumor activity.

Inhibition of (mono)amine oxidase activity and prevention of ifosfamide encephalopathy by methylene blue.

The clinical application of ifosfamide is hampered by a central nervous side effect, the so-called ifosfamide encephalopathy. Methylene blue is effective in prophylaxis and reversal of this side effect. In the present study, the in vitro inhibition of (mono)amine oxidases by methylene blue is demonstrated in two different experimental systems. The results provide an explanation for the preventive action of methylene blue in ifosfamide neurotoxicity, because the generation of chloroacetaldehyde (a potential neurotoxin of ifosfamide metabolism) is prevented in liver mitochondria and extrahepatic tissues. Generation of alkylating metabolites was also studied in rat liver perfusions, and methylene blue did not show any inhibition of ifosfamide activation. From these data, we conclude that the clinical effectiveness of methylene blue in treatment and prevention of ifosfamide encephalopathy might be based on inhibition of (mono)amine oxidases. Hepatic bioactivation of ifosfamide is not influenced by methylene blue.

Sensitization of human breast cancer cells to cyclophosphamide and ifosfamide by transfer of a liver cytochrome P450 gene.

The cancer chemotherapeutic agent cyclophosphamide (CPA) and its isomer ifosfamide (IFA) are alkylating agent prodrugs that require metabolism by liver cytochrome P450 (P450) enzymes for antitumor activity. The therapeutic effectiveness of these oxazaphosphorines is limited by the hematopoietic, renal, and cardiac toxicity that accompanies the systemic distribution of liver-derived activated drug metabolites. Transfer of a liver cytochrome P450 gene, CYP2B1, into human breast MCF-7 cancer cells is presently shown to greatly sensitize these cells to oxazaphosphorine toxicity as a consequence of the acquired capacity for intratumoral CPA and IFA activation. Thus, CPA and IFA were highly cytotoxic to MCF-7 cells following stable transfection of CYP2B1 but exhibited no toxicity to parental tumor cells or to a beta-galactosidase-expressing MCF-7 transfectant. This cytotoxicity could be appreciably blocked by the CYP2B1 inhibitor metyrapone. Cell cycle analysis revealed that CPA arrested the CYP2B1-expressing cells, but not CYP2B1-negative cells, at G(2)-M phase. A strong bystander cytotoxicity effect that does not require direct cell-cell contact was mediated by CYP2B1-expressing MCF-7 cells on non-CYP2B1 cells. Intratumoral CYP2B1 expression conferred a distinct therapeutic advantage when treating MCF-7 tumors grown in nude mice with CPA, as revealed by a 15-20-fold greater in vivo cytotoxicity, determined by tumor excision/colony formation assay, and by the substantially enhanced antitumor activity, monitored by tumor growth delay, for CYP2B1-e xpressing MCF-7 tumors as compared to CYP2B1-negative control tumors. These enhanced therapeutic effects were obtained without any apparent increase in host toxicity. To evaluate the extent to which a CPA/P450 gene therapy strategy may be generally applicable to other tumor cell types, a replication-defective recombinant adenovirus carrying the CYP2B1 gene driven by the cytomegalovirus (CMV) promotor ad.CMV-2B1 was constructed and used to infect a panel of human tumor cell lines. Ad.CMV-2B1 infection rendered each of the cell lines highly sensitive to CPA and IFA cytotoxicity, with substantial chemosensitization seen at multiplicities of infection as low as 10. The CPA/P450 prodrug activation system may thus serve as a useful paradigm for further development of novel cancer gene therapy strategies that utilize drug susceptibility genes to significantly potentiate the antitumor activity of conventional cancer chemotherapeutic agents.

Ifosfamide, mesna, and nephrotoxicity in children.

PURPOSE: With the increasing use of ifosfamide in pediatric malignancies, nephrotoxicity has emerged as a potentially serious adverse effect, which may be dose-limiting or may cause severe chronic morbidity, including glomerular impairment and/or Fanconi's syndrome. The purpose of this review was (1) to improve the documentation of ifosfamide nephrotoxicity in children, and (2) to consider the possible causative role of ifosfamide metabolites. DESIGN: (1) A grading system was developed that allowed documentation of the nature and severity of published reports of ifosfamide-induced nephrotoxicity, and evaluation of patient and treatment-related risk factors. (2) The relationship between the pharmacology of ifosfamide/mesna and nephrotoxicity was investigated by examination of published data, especially that concerning the quantitative differences in the metabolism of ifosfamide and its nonnephrotoxic structural isomer, cyclophosphamide. RESULTS: (1) Examination of 16 published reports (with assessable data from 40 children) demonstrated that ifosfamide-induced nephrotoxicity was associated with a wide range of patient ages and ifosfamide cumulative doses given by different administration schedules. (2) Chloroacetaldehyde, a major metabolite of ifosfamide only, may be at least partly responsible for the renal toxicity of this drug. Although mesna may be capable of detoxifying the toxic metabolite(s), delivery to the renal tubule may not be sufficient to provide adequate protection of tubular glutathione from depletion by the metabolite(s), which results in a failure to prevent nephrotoxicity. CONCLUSION: Increased understanding of the interindividual variability in the extent and nature of ifosfamide metabolism, which may be a major determinant of susceptibility to renal damage, may lead to improved use of the drug with less nephrotoxicity.

Feasibility and efficacy of arginine 2-mercaptoethanesulfonate (ARGIMESNA) in the prevention of hemorragic cystitis from ifosfamide (IFO).

Tolerability and efficacy of the new uroprotective agent ARGIMESNA was assessed within a randomized cross-over study comparing it to sodiummercaptoethanesulfonate (MESNA), in patients treated with IFO. MESNA i.v., 20% of IFO dose, was given to all patients before chemotherapy; 4 h later, at random, they received ARGIMESNA p.o., 20% of IFO dose every 2 h x 4, or MESNA p.o., 40% of IFO dose every 4 h x 2. Overall, 78 cycles of oral uroprotection were administered: 37 for ARGIMESNA capsules; 41 for MESNA vials p.o. ARGIMESNA was subjectively better tolerated, determining gastro-intestinal discomfort in only 12 out of 37 cycles versus 34/41 of MESNA p.o. (p less than 0.001). Both preparations were equivalent for subjective and objective efficacy since no cycles were complicated by urinary symptoms (dysuria, stranguria, or hematuria). Nevertheless, 2 patients (7.7%) refused further oral assumption of both uroprotectors, whereas MESNA i.v. was added in other 7 patients because of nausea and vomiting caused by chemotherapy. In conclusion, this new oral preparation of mercaptoethanesulfonate turned out to be well tolerated, safe and active in the prevention of haemorrhagic cystitis from IFO.

Drug interaction effects on antitumour drugs (VIII): prevention of ifosfamide-induced urotoxicity by disulfiram and its effect on antitumour activity and acute toxicity of alkylating agents in mice.

To reduce the side-effects and to enhance the antitumour activities of antitumour agents, we have been investigating their combined use with routine drugs. In the present study, we examined the effects of disulfiram (DSF) in combination with ifosfamide (IFX). DSF prevented IFX-induced bladder damage in a dose-dependent manner in tumour-free ddY mice when orally administered simultaneously with antitumour agent, but failed to diminish the acute lethal toxicity or leukocytotoxicity of IFX. Diethyldithiocarbamate (DDTC) prevented IFX-induced bladder damage when administered simultaneously with IFX or 1 to 5 hr afterwards. The antitumour activity of IFX in ddY-mice inoculated with Sarcoma 180 or in C57BL/6J mice inoculated with EL-4 leukaemia was not impaired when it was given simultaneously with DSF or 3 hr before DDTC. Thus, neither DSF nor DDTC impaired the antitumour effect of IFX and both diminished its adverse effects. The bladder protection of DSF and DDTC appeared resulted from adduct formation with acrolein and not from inhibition of the metabolic activation of IFX.

[Ifosfamide-induced urinary bladder lesion and its inhibition by mesna].

This study examined the characteristics of urinary bladder lesions (cystitis) induced by ifosfamide (IF), an antitumor agent, and their inhibition by mesna in rats. Single i.v. doses of 50 mg/kg or more of IF induced cystitis characterized by increased bladder weight with mucosal hemorrhage and edema within 3 hr, with a plateau being reached 1 to 3 days after the injection. This change occurred earlier than myelotoxicity. Injection of IF to ureter-ligated rats did not induce the cystitis. Also, when IF was infused to one of a pair of rats in which the ureters had been crossed, the cystitis occurred only in the non-injected member of the pair whose bladder received urine flow from the IF-injected rat. Cystitis did not occur with direct injection of 10 mg of IF into the urinary bladder, but did with injection of the metabolite, 14 micrograms of acrolein. These findings show that IF-induced cystitis is not a systemic effect like myelotoxicity or an antitumor effect but a local effect. The cystitis could be completely inhibited by mesna, and this effect, which was dose-dependent, occurred from one-tenth of the IF dose. The effect was strongest when mesna was administrated within 1 hr of the IF injection. There was little difference in the effect between single and divided doses. The combined administration of IF with mesna did not lower the antitumor effect of IF.

Protection from ifosfamide-induced alopecia by topical thiols in young rats.

An animal model for testing substances that might prevent alopecia induced by oxazaphosphorines has been developed. It is based on the fact that the rat pups experience virtually total hair loss following administration of oxazaphosphorines. Using this model, we showed that epicutaneous treatment with sodium thioglycollate prevented ifosfamide-induced hair loss on the treated area. These experiments indicate that prevention of oxazaphosphorine-induced alopecia in man may be achieved by topical thiols.

Phase II trial of ifosfamide and mesna in previously treated patients with non-Hodgkin's lymphoma: Cancer and Leukemia Group B Study 8552.

Ifosfamide (1.25 g/m2 intravenously/day x 5) with mesna (20% of the ifosfamide dose x six doses on each day of ifosfamide therapy) was administered to 46 previously treated patients with non-Hodgkin's lymphoma of which 31 were eligible and evaluable. A 29% response rate (9/31) was observed (2 CR and 7 PR) with a median duration of response of 2.5 months. Myelosuppression was dose-limiting. Hemorrhagic cystitis was observed in three patients (10%). Nausea and vomiting was generally mild or moderate. One patient developed transient neurotoxic symptoms with confusion and disorientation. An additional patient developed an anaphylactic-type reaction with shortness of breath and respiratory strider during the fourth course of therapy. Ifosfamide, as a single agent, produces remissions of limited duration in non-Hodgkin's lymphoma in patients in second or third relapse.

Prevention of urotoxic side effects by regional detoxification with increased selectivity of oxazaphosphorine cytostatics.

Urotoxic side effects, particularly haemorrhagic cystitis, have been a limiting factor for the therapeutic use of the oxazaphosphorine cytostatics cyclophosphamide, ifosfamide and trofosfamide. The development of mesna (Uromitexan) has made it possible to carry out regional detoxification in the kidneys and the efferent urinary tract and thus to achieve clinically prophylaxis against the urotoxic side effects of oxazaphosphorines. In the body, mesna is rapidly converted to the biologically inactive disulfide form (dimesna). After glomerular filtration, dimesna is reduced by interaction with the glutathione system of the renal tubular cells and is excreted in the urine as mesna, the free thiol compound. This compound is then capable of definitively detoxifying the oxazaphosphorine metabolites in the urine. In extensive experiments on rats, it has been demonstrated that the cyclophosphamide-induced occurrence of urinary bladder tumours could be reduced or even eliminated by simultaneous administration of mesna. Detoxification by mesna enables the clinical use of higher doses and, consequently, a possible increase in therapeutic efficiency.

[Prevention of urotoxic actions of cyclophosphamide and ifosfamide by dimesna (preliminary communication) (author's transl)]. / Verhütung urotoxischer Wirkungen von Cyclophosphamid und Ifosfamid durch Dimesna (Vorläufige Mitteilung).

Sodium 2-mercaptoethane sulfonate (mesna, Uromitexan) is oxidized in the organism of rats to 2,2'-dithiodi-(ethane sodium sulfonate) (dimesna). Dimesna is partially reduced to the mercapto compound mesna (kidneys); both compounds are eliminated via the urine. Even after administration of dimesna mesna can be detected in the urine. Accordingly dimesna also proved to be an effective antidote against the urotoxic actions of cyclophosphamide and ifosfamide.

Prevention of isophosphamide-induced urothelial toxicity with 2-mercaptoethane sulphonate sodium (mesnum) in patients with advanced carcinoma.

In 8 patients receiving intravenous isophosphamide 2 g/m2 at 2-week intervals for advanced bronchogenic carcinoma the protective effect of 2-mercaptoethane sulphonate sodium (mesnum) against isophosphamide-induced urothelial toxicity was tested in a single-blind crossover trial. With isophosphamide alone, 7 of the 8 patients developed either haematuria or symptoms of bladder irritation; when mesnum was given in addition, only 1 patient had microhaematuria and frequency, and this was in association with a urinary-tract infection. 5 patients then received fifteen courses of isophosphamide in increasing doses of 4 to 8 g/m2 i.v. with mesnum. In contrast to previous experience with isophosphamide at this high dosage, frank haematuria was never seen, microhaematuria was seen after only three courses, and mild dysuria after only one course. Pharmacokinetic studies showed that mesnum did not interfere with the metabolism of isophosphoramide or its active anti-tumour metabolite, isophosphoramide mustard. Mesnum therefore enhances the therapeutic ratio of isophosphamide and may thereby increase its clinical efficacy.