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PubMed1990

Cyclophosphamide and abrogation of tumor-induced suppressor T cell activity.

Previously we have demonstrated that the in vitro generation of P815-specific anti-tumor cytotoxic T lymphocytes (CTL) was suppressed by splenic suppressor T cells from late tumor-bearing hosts (TBH). Suppression is not caused by in vitro growth of P815 from splenic metastases, since suppression was also seen with spleen cells from late TBH mice bearing a hypoxanthine/aminopterin/thymidine-sensitive subline (PHS-5) of P815 in the presence of HAT. Cyclophosphamide has been shown to inhibit the induction of suppressor cells selectively in a number of immune responses, but evidence that it can inhibit active tumor-induced suppressor T cells is limited. We have found that suppressor T cells already induced by P815 in syngeneic late TBH are sensitive to low doses of cyclophosphamide (50 mg/kg) given 1 day before spleen harvest, but the in vitro CTL response of late TBH spleen cells could not be restored by pretreating the mice with cyclophosphamide, even when exogenous interleukin-2 was added to the cultures. Although 50 mg/kg cyclophosphamide did not inhibit the CTL response of spleen cells from mice immunized with P815 + Corynebacterium parvum, the same dose of cyclophosphamide eliminated the CTL response of spleen cells from early TBH. Interleukin-2 (IL-2) did not overcome this effect of cyclophosphamide, suggesting a direct effect on CTL. "Ultra-low" -dose cyclophosphamide (10 mg/kg) did not adversely effect early TBH CTL but was still able to eliminate suppressor T cell activity from late TBH. Nevertheless, late TBH CTL remained unresponsive after pretreatment of mice with ultra-low-dose cyclophosphamide, even when exogenous IL-2 was added in vitro. CTL precursor frequency analyses demonstrated that cyclophosphamide pretreatment had little or no effect on the numbers of CTL precursors from early TBH. Late TBH CTL precursor cells were not detectable in these studies, with or without suppressor T cell inhibition by cyclophosphamide pretreatment. Thus, it appears that most CTL precursor cells may be lost or irretrievably inactivated in the spleens of late TBH mice.

Animals↗

PubMed1988

Pharmacokinetics of intravenous and oral cyclophosphamide in the presence of methotrexate and fluorouracil.

Cyclophosphamide was administered to 12 breast cancer patients in combination with methotrexate and fluorouracil. Doses prescribed were cyclophosphamide 75 mg/m2, methotrexate 30 mg/m2 and fluorouracil 500 mg/m2 (per square meter body surface). Cyclophosphamide was administered intravenously and orally in aqueous solutions and in tablets in a randomized cross-over trial. Methotrexate and fluorouracil were administered intravenously, methotrexate was given first and then fluorouracil. Assays of cyclophosphamide in blood plasma were performed by capillary gas chromatography. Data of mean bioavailability of cyclophosphamide administered by tablets were suggestive of sufficient absorption. In 2 patients, however, a lower bioavailability of cyclophosphamide was demonstrated. Intra-individual differences in the terminal slope of the plasma decay curves after intravenous and oral administration in some patients decreased the calculated bioavailability of cyclophosphamide, if these values were included in the calculation of cyclophosphamide bioavailability. Compared with the administration of the solutions peak times, lag-times and mean absorption times of cyclophosphamide given in tablets were markedly prolonged. It is concluded that interactions between cyclophosphamide and methotrexate and/or fluorouracil after oral dosing as tablets are different from interactions observed after intravenous administration of cyclosphosphamide.

Administration, Oral↗

PubMed1989

Influence of metabolic factors on the mutagenic effectiveness of cyclophosphamide in Drosophila melanogaster.

This paper describes the influence of changes in metabolic activity on the in-vivo mutagenic effectiveness of cyclophosphamide in Drosophila melanogaster. A dose-dependent increase in mutagenicity was observed until a plateau value is reached which was increased only slightly after enzyme induction with Aroclor 1254, whereas induction with phenobarbital resulted in a decrease, especially when cyclophosphamide was applied by injection. Treatment of the adult males with inhibitors of the monoamine oxidase (MAO, EC 1.4.3.4), such as iproniazid (Ipr), benzimidazole or tryptamine, led to a marked increase of the mutagenic effectiveness of cyclophosphamide especially in spermatocytes. This indicates the importance of metabolic de-activation processes for the limited mutagenicity of cyclophosphamide in Drosophila. The principal active metabolite of cyclophosphamide, phosphoramide mustard, is extensively de-activated by enzymes that can be inhibited by 1-phenylimidazole (PhI), presumably cytochrome P-450 (EC 1.14.14.1), but not by those blocked by MAO inhibitors. Inhibition of the FAD-containing dimethylaniline monooxygenase (FDMAM, EC 1.14.13.8) by N,N-dimethylbenzylamine (N,N-DMB) resulted in some increase in cyclophosphamide mutagenicity only in spermatids. The marginal mutagenicity of cyclophosphamide in Drosophila larvae could not be increased either by cytochrome P-450 induction with phenobarbital or by MAO inhibition with Ipr. In contrast to the failure of cyclophosphamide to induce rod-chromosome loss, a considerable activity was found when a ring-shaped chromosome was used. Similar to the sex-linked recessive lethal (SLRL) test, ring-X loss frequency could be enhanced by simultaneous treatment with MAO inhibitors. The observed ring-X loss frequency declined when males treated with cyclophosphamide were mated to DNA-repair deficient mei-9L1 females. Cyclophosphamide produces chromosome breaks, detected as 2-3 translocations, in Drosophila spermatocytes, the stage in spermatogenesis that is also the most sensitive to the induction of SLRL mutations.

Animals↗

PubMed1990

Voluntary consumption of cyclophosphamide by nondeprived Mrl-lpr/lpr and Mrl +/+ mice.

Cyclophosphamide dissolved in several dilutions of chocolate milk was presented for 20 hr daily to nondeprived, symptomatic, autoimmune Mrl-lpr/lpr and asymptomatic Mrl +/+ mice. In the absence of cyclophosphamide, daily consumption was inversely related to the concentration of the chocolate milk solutions and increased from the first to the fourth day of exposure. There were no effects of strain or sex on the consumption of plain chocolate milk. Consumption of 0.1 or 0.2 mg cyclophosphamide per ml of different dilutions of chocolate milk increased over days 1-4 and decreased on day 8. Consumption of 0.4 mg/ml cyclophosphamide did not change over days. Generally, consumption was inversely related to the cyclophosphamide concentration. Females consumed more cyclophosphamide than males. Autoimmune lpr/lpr mice consumed more cyclophosphamide than +/+ mice. Dilution of chocolate milk had no effect on consumption of cyclophosphamide. Lymphoproliferation and anti-ssDNA antibody titer were reduced by the consumption of cyclophosphamide-chocolate milk solutions. It is hypothesized that autoimmune lpr/lpr mice voluntarily consume more cyclophosphamide than asymptomatic +/+ mice in an effort to "correct" their immune system dysregulation.

Animals↗

PubMed1991

Cyclophosphamide 24 hours before or after total body irradiation: effects on lung and bone marrow.

Preparative regimens for bone marrow transplantation (BMT) use a sequence of drugs, such as cyclophosphamide, in combination with radiation. However, the optimum sequencing of the two agents that will maximize tumor cell kill and minimize normal tissue damage is unknown and controversial. The studies presented here were done in order to determine the effect of cyclophosphamide on bone marrow and lung damage in mice when given 24 h before or after total body irradiation (TBI). A range of single doses of TBI was given before or after a single sublethal dose of 180 mg/kg of cyclophosphamide. The bone marrow of all mice intended for lung damage assessment was reconstituted with 5 x 10(6) syngeneic bone marrow cells. Lung damage was assessed by breathing rate and lethality; bone marrow damage by lethality at 30 days. LD50 values for pneumonitis were obtained between 30 and 84 days after cyclophosphamide and radiation and between 80 and 180 days after radiation alone. Dose modifying factors were obtained as the ratio of LD50s for mice given only TBI compared to those for mice given cyclophosphamide and TBI. Cyclophosphamide enhanced radiation pneumonitis when given before or after TBI, giving DMFs of 1.4 and 1.2 (1.1-1.4, 95% c.l.) respectively. The effect of cyclophosphamide on radiation pneumonitis was drug dose-dependent. The LD50 for death from bone marrow damage was reduced when cyclophosphamide was given either before or after TBI but the effect was greater, i.e. the LD50 was lower when cyclophosphamide was given after TBI. These data show that cyclophosphamide given 24 h after TBI causes less lung damage but more bone marrow damage in this mouse model.

Animals↗

PubMed2006

Cyclophosphamide augments inflammation by reducing immunosuppression in a mouse model of allergic airway disease.

BACKGROUND: Allergic asthma is a TH2 cell-driven immunological disease, characterized by eosinophilic inflammation. The cytotoxic agent cyclophosphamide paradoxically augments several immune responses. OBJECTIVE: We studied the proposal that cyclophosphamide may aggravate airway inflammation in allergic mice, and these features might result from the loss of regulatory T cells. METHODS: BALB/c mice were immunized with ovalbumin on days 0 and 14 and challenged with aerosolized ovalbumin from days 21 to 27. Some mice also received cyclophosphamide on days -2 and 12. RESULTS: In the lungs of cyclophosphamide-treated animals, pronounced worsening of inflammatory features was noted, including increased eosinophil infiltration, epithelial thickness, mucus occlusion, and eosinophil numbers in bronchoalveolar lavage fluid. There was also increased total and ovalbumin-specific serum IgE, increased IL-4 and IL-5 secretion by peritracheal lymph node cells, and reduced lung mRNA expression of IL-10 and TGF-beta in animals treated with cyclophosphamide. The expression of FoxP3, a marker of regulatory T cells, was significantly reduced in lymphoid organs after the second injection of cyclophosphamide, and in the lung tissue after allergen challenge in cyclophosphamide-treated mice. Lung IL-10+CD4+ T cells and cytotoxic T lymphocyte-associated antigen 4+CD4+ T cells were reduced after allergen challenge in cyclophosphamide-treated mice. CONCLUSION: Cyclophosphamide worsened features of allergic pulmonary inflammation in this model, in association with increased production of IgE and TH2 cytokines. The reduced expression of FoxP3 and immunosuppressive cytokines by cyclophosphamide is consistent with the possibility that toxicity to regulatory T cells may contribute to the increased inflammation.

Adjuvants, Immunologic↗

PubMed2005

[Cardiopulmonary function before and after cyclophosphamide treatment in severe systemic sclerosis: comparison of monthly intravenous bolus and autologous haematopoietic stem cell transplantation].

PURPOSE: Cyclophosphamide in monthly intravenous bolus is used to treat severe forms of systemic sclerosis with pulmonary involvement. Since 1996, cyclophosphamide therapeutic intensification with autologous haematopoietic stem cells transplantation allowed significant improvement in skin and functional scores in severe systemic sclerosis. Cyclophosphamide potential cardiotoxicity in this setting has been questioned. METHODS: To analyse cyclophosphamide potential cardiopulmonary toxicity (as graded with WHO classification), we retrospectively studied all severe systemic sclerosis patients treated with cyclophosphamide either during autologous haematopoietic stem cells transplantation procedure (group A) or intravenous cyclophosphamide (group B) recruited in 7 French centers volunteers for the study. Parameters to evaluate heart and lung functions at inclusion, then at last follow-up between 6 and 12 months after start of treatment, were compared using the Mann-Whitney test. RESULTS: (Mean+/-standard deviation): Groups A (N=14) and B (N=13) were similar at the beginning of the study in terms of skin, renal, heart and lung involvement. Cyclophosphamide total dose (/m(2)) received in group A was superior (P=0.02) to the one in group B. After respective follow-up of 10+/-2.8 (group A) and 9.9+/-2.7 (group B) months, cyclophosphamide cardio toxicity (group A: N=3; group B: N=2), evolution of the left ventricular ejection fraction and arterial and pulmonary pressures did not differ in the two groups. CONCLUSION: In spite of higher cyclophosphamide doses during autologous haematopoietic stem cells transplantation than bolus treatment, cardiopulmonary toxicity appeared not increased. The ongoing European ASTIS trial will compare the respective benefits of these 2 cyclophosphamide regimens in severe Systemic sclerosis.

Adolescent↗

PubMed1998

Pharmacokinetics of cyclophosphamide and its metabolites in bone marrow transplantation patients.

OBJECTIVES: To characterize the pharmacokinetics of cyclophosphamide and 5 of its metabolites in bone marrow transplant patients and to identify the mechanism of the increase in 4-hydroxycyclophosphamide area under the plasma concentration-time curve (AUC) from day 1 to day 2 of cyclophosphamide administration. METHODS: Cyclophosphamide was administered by intravenous infusion (60 mg/kg over 1 hour, once a day) for 2 consecutive days to 18 patients. Cyclophosphamide and 4-hydroxycyclophosphamide concentration time data on day 1 and day 2 were fitted to a model to estimate 4-hydroxycyclophosphamide formation (CLf) and elimination (CLm) clearances. Erythrocyte aldehyde dehydrogenase-1 activity was measured ex vivo just before the first cyclophosphamide infusion was started (0 hours) and 24 hours after the second cyclophosphamide infusion (48 hours). RESULTS: From day 1 to day 2, the AUC of cyclophosphamide, deschloroethyl cyclophosphamide and phosphoramide mustard decreased 24.8%, 51%, and 29.4% (P < .02), the AUC of 4-hydroxycyclophosphamide and carboxyethylphosphoramide mustard increased 54.7% and 25% (P < .01), whereas the AUC of phosphoramide mustard was not significantly changed (P > .3). The CLf of 4-hydroxycyclophosphamide increased 60% (P < .001), its CLm decreased 27.7% (P < .001), and the fraction of cyclophosphamide dose converted to 4-hydroxycyclophosphamide increased 16% (P < .001) from day 1 to day 2. The activity of patient erythrocyte aldehyde dehydrogenase-1 decreased 23.3% (P < .02) from 0 hours to 48 hours. CONCLUSIONS: The AUC of 4-hydroxycyclophosphamide increased from day 1 to day 2 as a result of increased formation and decreased elimination clearances of 4-hydroxycyclophosphamide. Aldehyde dehydrogenase-1 activity appears to decline as a consequence of cyclophosphamide administration.

Aldehyde Dehydrogenase↗

PubMed2003

Pulse cyclophosphamide inadequately suppresses reoccurrence of minimal change nephrotic syndrome in corticoid-dependent children.

BACKGROUND: In minimal change nephrotic syndrome (MNCS), the most common primary nephrotic syndrome in children, approximately 95% of cases show excellent responses to steroid therapy. However, responding patients may become steroid dependent and experience serious side effects. Although oral cyclophosphamide has been recommended in these patients, long-term side effects such as gonadal toxicity are an important concern. Therefore, cyclophosphamide pulses given intravenously may provide an option that maintains remission with less-frequent side effects. METHODS: We treated 20 primary steroid-dependent MCNS patients (15 boys and five girls) with intravenous cyclophosphamide. The patients were children with ages ranging from 3 to 15 years of age. Remission was induced by steroids followed by cyclophosphamide at a dose of 500 mg/m2 body surface area per month for 6 months. During this period, we attempted to completely withdraw steroids and maintain patients on cyclophosphamide alone. We monitored the patients for the occurrence of relapse and side effects during this period and for an additional 6 months after withdrawal of cyclophosphamide. RESULTS: At the end of the 6-month cyclophosphamide treatment period (i.e. 4 months after steroid discontinuation), nine patients (45%) were in remission on cyclophosphamide alone. However, patients that maintained treatment-free remission (cyclophosphamide responders) decreased to five (25%), two (10%) and one (5%) at 6 months, 1 year and 2 years, respectively. CONCLUSION: We found that a 6-month course of pulse cyclophosphamide produced unfavourable effects in the majority of paediatric patients with steroid-dependent nephrotic syndrome.

Child↗

PubMed2004

Application of liquid chromatography-mass spectrometry to monitoring plasma cyclophosphamide levels in phase I trial cancer patients.

A specific and efficient liquid chromatography-mass spectrometry (LC-MS) method was established for monitoring patient plasma cyclophosphamide levels in a phase I trial of an oral cyclophosphamide-based combination chemotherapy regimen. An Agilent 1100 Series LC-MSD system (Agilent Technologies, Avondale, PA, USA), with a single quadrupole mass detector using a positive atmospheric pressure chemical ionization (APCI) interface and single ion monitoring at m/z 261, was used. Chromatography was performed using a LUNA C8 5 microm 30 x 4.6 mm stainless steel column (Phenomenex, Torrance, CA, USA) and a mobile phase of aqueous acetonitrile pumped at a flow rate of 0.7 mL/min. High-throughput solid-phase sample extraction was performed using a Gilson ASPEC XL4 system (Gilson Medical, Middleton, WI, USA) controlled by prestored programs. The standard curve for cyclophosphamide was linear over the concentration range 0.026-1.08 microg/mL (r(2) > 0.994). Intra- and interassay accuracy and precision were 97-107 and 3-10%, respectively. The limit of detection was determined to be 0.01 microg/mL. Single ion monitoring at m/z 261 provided a high degree of specificity without interference from the matrix or other chemotherapy drugs. Automated sample processing allowed the analysis of a large number of plasma samples from a clinical trial of repeated daily oral dosing of cyclophosphamide. One hour after dosing, cyclophosphamide was detected in 98 of 106 plasma specimens at concentrations ranging between 0.03 and 4.88 microg/mL. Twenty-four hours after dosing, cyclophosphamide was detected in 72 of 77 plasma specimens at concentrations ranging between 0.06 and 3.13 microg/mL. There were no time-dependent changes in cyclophosphamide concentration during the 43 day period of repeated daily oral dosing. There was no correlation between cyclophosphamide dose and plasma concentration, despite the wide range of doses given in the clinical trial (50-125 mg/m(2)). We conclude that a solid-phase extraction LC-MS technique was validated for determining cyclophosphamide in human plasma. Interoccasion variability in the rate of oral absorption and in the clearance of systemically available drug may have contributed to the wide range of cyclophosphamide concentrations found at 1 and 24 h after tablet ingestion.

Antineoplastic Agents↗

PubMed1977

Corticosteroid effect on granulopoiesis in mice after cyclophosphamide.

Corticosteroids cause an enhanced return of granulopoiesis as measured by in vitro growth of granulocytic progenitor cells (CFU-C) in mice treated with cyclophosphamide. After methylprednisolone and cyclophosphamide, a greater than threefold increase in marrow CFU-C was measured on day 4 compared to mice given cyclophosphamide alone (29,700+/-200 vs. 8,400+/-700/humerus). The accelerated return of marrow CFU-C was observed with cyclophosphamide in doses of 200 and 450 mg/kg and methylprednisolone, 2-20 mg/kg, with no significant differences using >5 mg/kg, and was detected when dexamethasone was used in place of methylprednisolone. This effect was accompanied by similarly enhanced splenic granulopoiesis as measured by CFU-C concentration. Levels of colony stimulating activity did not differ in mice given methylprednisolone and cyclophosphamide or cyclophosphamide alone. Corticosteroids appear to enhance the return of CFU-C by altering the proliferative state of granulocytic progenitor cells. CFU-C survival to in vitro (3)HTdR suicide increased from 72+/-4% on day 1 after cyclophosphamide to 90+/-6% in animals given both cyclophosphamide and methylprednisolone. Increased survival after (3)HTdR suicide was also observed when methylprednisolone alone was given. After treatment with cyclophosphamide and methylprednisolone, blood neutrophils increased more rapidly and improved survival to infection with Candida albicans was observed. These studies demonstrate that corticosteroids have a beneficial effect on marrow regeneration after myelotoxic chemotherapy with cyclophosphamide and suggest that they act by altering cell cycle characteristics of granulocyte progenitor cells.

Animals↗

PubMed2005

Role of lupeol and its ester on cyclophosphamide-induced hyperlipidaemic cardiomyopathy in rats.

Cyclophosphamide, an alkylating agent widely used in cancer chemotherapy, causes fatal cardiotoxicity. In this study, lupeol, a pentacyclic triterpene isolated from Crataeva nurvala stem bark, and its ester, lupeol linoleate, were investigated for their possible hypocholesterolaemic effects against cyclophosphamide-induced lipidaemic instabilities. Male albino Wistar rats were categorized into 6 groups. Group I served as control. Rats in groups II, V and VI were injected intraperitoneally with a single dose of cyclophosphamide (200 mg kg(-1)) dissolved in saline. Cyclophosphamide-treated groups V and VI respectively received lupeol and lupeol linoleate (50 mg kg(-1)), dissolved in olive oil, for 10 days by oral gavage. Groups III and IV served as drug controls and were administered lupeol and lupeol linoleate, respectively. Cyclophosphamide administration induced abnormal changes in serum lipoproteins and lipid fractions in both serum and cardiac tissue. The activity of lipid metabolizing enzymes was distorted significantly in the cyclophosphamide-treated rats. The cyclophosphamide-treated rats also showed extensive intermuscular haemorrhage in histology. Lupeol and its ester reversed the above alterations induced by cyclophosphamide. This study encapsulates the early lipaemic abnormalities in the heart tissue of cyclophosphamide-treated rats. Treatment with lupeol linoleate was more effective than lupeol in rendering protection to the cardiac tissue challenged by cyclophosphamide.

Animals↗

PubMed2005

Clinical pharmacokinetics of cyclophosphamide.

Cyclophosphamide is an extensively used anticancer and immunosuppressive agent. It is a prodrug undergoing a complicated process of metabolic activation and inactivation. Technical difficulties in the accurate determination of the cyclophosphamide metabolites have long hampered the assessment of the clinical pharmacology of this drug. As these techniques are becoming increasingly available, adequate description of the pharmacokinetics of cyclophosphamide and its metabolites has become possible. There is incomplete understanding on the role of cyclophosphamide metabolites in the efficacy and toxicity of cyclophosphamide therapy. However, relationships between toxicity (cardiotoxicity, veno-occlusive disease) and exposure to cyclophosphamide and its metabolites have been established. Variations in the balance between metabolic activation and inactivation of cyclophosphamide owing to autoinduction, dose escalation, drug-drug interactions and individual differences have been reported, suggesting possibilities for optimisation of cyclophosphamide therapy. Knowledge of the pharmacokinetics of cyclophosphamide, and possibly monitoring the pharmacokinetics of cyclophosphamide in individuals, may be useful for improving its therapeutic index.

Antineoplastic Agents, Alkylating↗

PubMed1996

Cyclophosphamide-induced cystitis and bladder cancer in patients with Wegener granulomatosis.

OBJECTIVE: To describe the incidence of, clinical manifestations of, and risk factors for cyclophosphamide-induced urinary bladder toxicity in patients treated for nonmalignant disease. DESIGN: Retrospective analysis of patients followed at the National Institutes of Allergy and Infectious Diseases from 1967 to 1993. SETTING: The Warren G. Magnuson Clinical Center of the National Institutes of Health (NIH). PATIENTS: 145 patients who received cyclophosphamide for the treatment of Wegener granulomatosis and were followed for 0.5 to 27 years (median, 8.5 years), for a total of 1333 patient-years. MEASUREMENTS: Clinical characteristics, cystoscopic findings, results of cytologic examination of urine, surgical pathology, and total dose and duration of cyclophosphamide therapy were recorded and analyzed using a computer-based information retrieval system. RESULTS: Nonglomerular hematuria occurred in 73 of 145 patients treated with cyclophosphamide (50%). Sixty of the 73 patients with nonglomerular hematuria (82%) had cystoscopy at the NIH. Forty-two of the 60 patients (70%) who had cystoscopy had macroscopic changes consistent with cyclophosphamide-induced bladder injury. Seven patients (5%) developed transitional-cell carcinoma of the urinary bladder. In 6 of these 7 patients, the total cumulative cyclophosphamide dose exceeded 100 g, and the cumulative duration of cyclophosphamide therapy exceeded 2.7 years. Before they were given a diagnosis of bladder cancer, all 7 patients had had one or more episodes of microscopic or gross nonglomerular hematuria. In contrast, none of the 72 patients who had never had nonglomerular hematuria developed bladder cancer. Cox proportional hazards regression analysis showed that only microscopic nonglomerular hematuria was a significant risk factor for the development of bladder cancer (P < 0.01). CONCLUSION: Long-term oral cyclophosphamide therapy is associated with substantial urotoxicity, including the development of transitional-cell carcinoma of the urinary bladder. In this cohort of patients, the estimated incidence of bladder cancer after the first exposure to cyclophosphamide was 5% at 10 years and 16% at 15 years. Nonglomerular hematuria was a frequent manifestation of cyclophosphamide-induced cystitis, and it identified a subgroup of patients at high risk for the development of bladder cancer.

Aged↗

PubMedDate not supplied

Effects of single and combined maltose tetrapalmitate immunotherapy, cyclophosphamide chemotherapy and radiotherapy on ethyl carbamate accelerated primary lung cancer in A/J mice.

A/J mice were given ethyl carbamate to accelerate and to raise to 100 percent the incidence of lung tumours at 34 weeks (day 237) of age. The animals were then divided into groups which received the following treatments: group 1, no treatment; group 2, MTP alone; group 3, radiotherapy alone; group 4, cyclophosphamide alone; group 5, radiotherapy + MTP; group 6, MTP + cyclophosphamide; group 7, radiotherapy followed by cyclophosphamide and group 8, MTP and radiotherapy together followed by MTP and cyclophosphamide. Except for radiotherapy, which was given for 5 consecutive days, MTP and cyclophosphamide were continued till the death of the animals. The treatment efficacies were evaluated by the number and size of tumour nodules, taking into consideration the survival time of the animal. Animals in groups receiving cyclophosphamide died earlier (between days 290 and 315) due to its toxic effects, and half of the radiotherapy-MTP were sacrificed at day 314 for comparison. Although cyclophosphamide alone and radiotherapy plus cyclophosphamide demonstrated antitumour activity, the number of tumour nodules and the nodule diameter were reduced most effectively in group 8 (receiving MTP, radiotherapy and cyclophosphamide). Among the animals in the non-cyclophosphamide group, radiotherapy alone was ineffective. MTP given before and after radiotherapy (group 5) kept tumour volume in control although this group died suddenly. The animals receiving only MTP died between day 430 and 470. The number of tumour nodules and the nodule diameter in the MTP group were, however, significantly reduced when compared to controls or radiotherapy group animals dying at or near the same time.

Animals↗

PubMed1982

Effect of disulfiram (tetraethylthiuram disulfide) amd diethyldithiocarbamate on the bladder toxicity and antitumor activity of cyclophosphamide in mice.

Cyclophosphamide is the most commonly prescribed alkylating agent in clinical medicine. The usefulness of cyclophosphamide is often limited, however, by its propensity to cause hemorrhagic cystitis especially in children or patients receiving concomitant radiotherapy. Administration i.p. of cyclophosphamide at doses of 100 mg/kg or more to mice produced a significant increase in urinary bladder weight within 48 hr of treatment. The present studies demonstrate that disulfiram prevented cyclophosphamide-induced bladder damage when administered p.o. within 1 hr of cyclophosphamide treatment. Diethyldithiocarbamate, a sulfhydryl-containing metabolite of disulfiram, had identical uroprotective activity. Unlike disulfiram, diethyldithiocarbamate was effective only when administered 2 to 4 hr after cyclophosphamide. Disulfiram augmented slightly the antitumor activity of cyclophosphamide against L1210 murine leukemia in vivo when administered 30 min prior to cyclophosphamide. In contrast, diethyldithiocarbamate had no effect on the antitumor activity of cyclophosphamide when administered 4 hr after cyclophosphamide.

Animals↗

PubMed1993

Cyclophosphamide modulates rat hepatic cytochrome P450 2C11 and steroid 5 alpha-reductase activity and messenger RNA levels through the combined action of acrolein and phosphoramide mustard.

Cyclophosphamide treatment of adult male rats leads to sustained decreases in several liver microsomal cytochrome P450 (CYP) activities, including CYP 2C11-catalyzed cyclophosphamide activation, via a process that is associated with a feminization of the overall pattern of liver enzyme expression (G. A. LeBlanc and D. J. Waxman, Cancer Res., 50:5720-5726, 1990). The present study compares the effects of cyclophosphamide and its isomeric analogue ifosphamide on the gender-dependent expression of hepatic CYP 2C11 and steroid 5 alpha-reductase in adult male rats and also examines the role of the cyclophosphamide metabolites acrolein and phosphoramide mustard in feminizing the expression of these liver enzymes. Ifosphamide (a) suppressed the male-specific CYP 2C11 mRNA and CYP 2C11-catalyzed liver microsomal testosterone 2 alpha-hydroxylation and cyclophosphamide and ifosphamide 4-hydroxylation and (b) elevated the female-dominant liver enzyme steroid 5 alpha-reductase and its mRNA 7-9 days after drug treatment, both occurring in a manner similar to that of cyclophosphamide, but requiring a 50% higher dose (180 mg/kg, single i.p. injection) to achieve these effects. This pattern of response could not be achieved by treatment of rats with acrolein or with cyclophosphamide analogues that decompose to acrolein without formation of phosphoramide mustard. In contrast, phosphoramide mustard treatment (100 mg/kg) did modulate microsomal CYP 2C11 and steroid 5 alpha-reductase activities. Treatment with a lower dose (50 mg/kg) of phosphoramide mustard or with the acrolein precursor 4-hydroperoxydechlorocyclophosphamide (200 mg/kg) alone did not affect liver enzyme expression, whereas the combination of these agents produced an overall pattern of response that was similar to that conferred by cyclophosphamide. These studies establish that ifosphamide is less potent than cyclophosphamide in modulating the pattern of cytochrome P450 and steroid 5 alpha-reductase expression and that phosphoramide mustard is responsible for the modulation of liver enzyme expression by cyclophosphamide, with acrolein potentiating the modulating activity of the mustard.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1976

Divergent effects of cyclophosphamide administration on mononuclear killer cells: quantitative depletion of cell numbers versus qualitative suppression of functional capabilities.

The effects of various regimens of cyclophosphamide administration on guinea pig peripheral blood leukocytes were studied. Cyclophosphamide-induced immunosuppression was assessed by the effect of drug administration on the proportions and absolute numbers of leukocyte populations, and by the effect on functional capabilities of unfractionated and adherent cell-depleted mononuclear cell suspensions as measured by the PHA-induced cellular cytotoxicity and antibody-dependent cellular cytotoxicity assays against chicken erythrocyte targets. Intraperitoneal administration of five daily doses of cyclophosphamide (5 mg/kg) caused a modest absolute leukopenia but no change in cytotoxic effector function of the mononuclear cells remaining in the circulation. As the dosage of cyclophosphamide was increased to 20 mg/kg/day to produce a pronounced leukopenia, a profound neutropenia (less than 300 polymorphonuclear leukocytes/mm3) together with a marked decrease in mononuclear cell effector function was noted. A single i.p. injection of cyclophosphamide (100 mg/kg), which produced identical degrees of leukopenia of each leukocyte class as did daily administration of cyclophosphamide (20 mg/kg/day), caused no change in mononuclear cell effector function when compared to saline controls. Complement receptor-bearing and Fc-receptor bearing mononuclear cells were decreased to the same degree by both regimens of cyclophosphamide administration. Removal of adherent cells from mononuclear cell suspensions by column purification resulted in a marked decrease in cytotoxic effector function at low effector to target ratios. At higher effector to target ratios there was no difference in cytotoxic effector function between unfractionated and column-purified cells. In contrast, the functional defect in mononuclear cell suspensions from animals that received five daily doses of cyclophosphamide (20 mg/kg) could not be compensated for at higher effector to target ratios, indicating that this functional defect was not an artifact of relative depletion of monocytes by cyclophosphamide, but was due to an actual suppression of the effector functional capabilities of the killer cells. This study indicates that, dependent on the particular regimen of drug administration, the quantitative depletion of mononuclear cell populations by cyclophosphamide administration can be clearly distinguished from the qualitative effect on certain functional capabilities of surviving cells.

Animals↗