Electronic volume analysis of L1210 chemotherapy.
The rapid analysis of in vivo chemotherapy on the L1210 ascites tumor grown in C57BL/6 X DBA/2F1 mice has been shown by means of an electronic volume analysis. The drugs were injected on the 4th day of tumor growth, and the cells in the peritoneal cavity were studied at 24-hr intervals on the 5th through 7th day. Using the electronic cell volume distributions, combined with labeling indices, cell morphology, and cell counts, it was found that the alkylating agents. 1,3-bis(2-chloroethyl)-1-nitrosourea and cyclophosphamide, at the dosages used, were more effective than the S-phase-specific drugs, palmitoyl ester of 1-beta-D-arabinofuranosylcytosine, vincristine, and methotrexate. (+info)
In vivo modulation of alternative pathways of P-450-catalyzed cyclophosphamide metabolism: impact on pharmacokinetics and antitumor activity.
The widely used anticancer prodrug cyclophosphamide (CPA) is activated in liver by a 4-hydroxylation reaction primarily catalyzed by cytochrome P-4502B and P-4502C enzymes. An alternative metabolic pathway involves CPA N-dechloroethylation to yield chloroacetaldehyde (CA), a P-4503A-catalyzed deactivation/neurotoxication reaction. The in vivo modulation of these alternative, competing pathways of P-450 metabolism was investigated in pharmacokinetic studies carried out in the rat model. Peak plasma concentrations (Cmax) for 4-OH-CPA and CA were increased by 3- to 4-fold, and apparent plasma half-lives of both metabolites were correspondingly shortened in rats pretreated with phenobarbital (PB), an inducer of P-4502B and P-4503A enzymes. However, PB had no net impact on the extent of drug activation or its partitioning between these alternative metabolic pathways, as judged from AUC values (area-under-the-plasma concentration x time curve) for 4-OH-CPA and CA. The P-4503A inhibitor troleandomycin (TAO) decreased plasma Cmax and AUC of CA (80-85% decrease) without changing the Cmax or AUC of 4-OH-CPA in uninduced rats. In PB-induced rats, TAO decreased AUCCA by 73%, whereas it increased AUC4-OH-CPA by 93%. TAO thus selectively suppresses CPA N-dechloroethylation, thereby increasing the availability of drug for P-450 activation via 4-hydroxylation. By contrast, dexamethasone, a P-4503A inducer and antiemetic widely used in patients with cancer, stimulated large, undesirable increases in the Cmax and AUC of CA (8- and 4-fold, respectively) while reducing the AUC of the 4-hydroxylation pathway by approximately 60%. Tumor excision/in vitro colony formation and tumor growth delay assays using an in vivo 9L gliosarcoma solid tumor model revealed that TAO suppression of CPA N-dechloroethylation could be achieved without compromising the antitumor effect of CPA. The combination of PB with TAO did not, however, enhance the antitumor activity of CPA, despite the approximately 2-fold increase in AUC4-OH-CPA, suggesting that other PB-inducible activities, such as aldehyde dehydrogenase, may counter this increase through enhanced deactivation of the 4-hydroxy metabolite. Together, these studies demonstrate that the P-4503A inhibitor TAO can be used to effectively modulate CPA metabolism and pharmacokinetics in vivo in a manner that decreases the formation of toxic metabolites that do not contribute to antitumor activity. (+info)
Antitumor agents. I. Effect of 5-fluorouracil and cyclophosphamide on liver microsomes and thymus of rat.
Effects of antitumor agents on rat liver microsomal drug-metabolizing enzyme activities and thymus lymphocytes were studied in male Wistar rats. High doses of 5-fluorouracil (5-FU) and cyclophosphamide (CP) given parenterally for 6 days caused a partial decrease in whole body weight and the microsomal enzyme content such as cytochrome P-450 and cytochrome b5. Aniline p-hydroxylase and aminopyrine N-demethylase activities also decreased in rats dosed for 5 days decreased compared with the control. Both compounds in the high concentrations produced spectral change of "modified type II". However, the magnitude of the spectral changes observed was independent of the the concentration of substrate added. The addition of NADPH to the microsomes-substrate mixture modified the spectral change. Both drugs caused a considerable decrease in thymus weight and the number of thymus lymphocytes, while the alkaline phosphatase activity was enhanced in 5-FU groups, indicating that the agents cause a significant involution of the thymus. Decrease in the total number of the lymphocytes was greater than that in the blood leucocytes. (+info)
Bone marrow transplantation in pediatric patients with therapy-related myelodysplasia and leukemia.
Eleven children underwent BMT for therapy-related MDS or leukemia, four from HLA-identical siblings and seven from unrelated donors. Ten of the 11 were conditioned with busulfan and cyclophosphamide as the majority had received prior irradiation to the chest and/or abdomen. All patients engrafted. Regimen-related toxicity was more common when compared to historical controls. Eight patients developed acute GVHD and four of eight who survived 100 days post transplant developed extensive chronic GVHD. Non-relapse related mortality occurred in three patients. Five patients developed recurrent malignancy: one died from recurrence of osteosarcoma, three died of recurrent leukemia or MDS and another developed two subsequent malignancies (duodenal carcinoma and anaplastic astrocytoma). Three survive disease-free at 14+, 22+ and 43+ months for a 2 year actuarial cancer-free survival of 24% (95% confidence interval = 5-53%). Although allogeneic BMT can be curative, regimen-related toxicity is frequent and recurrent malignancy remains the major obstacle. (+info)
Increase of hematopoietic responses by triple or single helical conformer of an antitumor (1-->3)-beta-D-glucan preparation, Sonifilan, in cyclophosphamide-induced leukopenic mice.
It has been suggested that the immunopharmacological activity of soluble (1-->3)-beta-D-glucan depends on its conformation in mice. In this study, we examined the relationship between the conformation of Sonifilan (SPG) and hematopietic responses in cyclophosphamide (Cy)-induced leukopenic mice. SPG, a high molecular weight (1-->3)-beta-D-glucan, has a triple helical conformation in water, and it was changed by treatment with aqueous sodium hydroxide to the single helical conformer (SPG-OH). The effects of SPG or SPG-OH on hematopoietic responses in cyclophosphamide induced leukopenic mice were investigated by monitoring i) gene expression of cytokines by RT-PCR, ii) protein synthesis of interleukin 6 (IL-6) by ELISA and iii) colony formation of bone marrow cells (BMC). The mice administered Cy and SPG or SPG-OH expressed and produced higher levels of IL-6 mRNA and protein than the mice administered only Cy. Gene expression of NK1.1 was also induced by Cy/SPG (or SPG-OH) treatment. Induced gene expression of stem cell factor (SCF) and macrophage-colony stimulating factor (M-CSF) by SPG/SPG-OH were also found in in vitro culture of BMC from Cy treated mice. These results strongly suggested that conformation of the glucans, single and triple helix, are independent of the hematopietic response. (+info)
The effect of fluconazole on cyclophosphamide metabolism in children.
Fluconazole is increasingly used in children receiving chemotherapy. Many of these patients are being treated with cyclophosphamide, which must undergo hepatic metabolism to produce active alkylating species. As a consequence of the cytochrome P-450 inhibitory properties of fluconazole, a potential interaction exists between these two agents that could influence the therapeutic effect of cyclophosphamide. To investigate this interaction, a retrospective case series of patients was chosen from a population of children with a previously established profile of cyclophosphamide metabolism. Twenty-two children who were not receiving other therapy known to influence drug metabolism were selected and analyzed in terms of fluconazole treatment; of these, nine were receiving fluconazole and thirteen were identified as controls. Study design was not randomized. The plasma clearance of cyclophosphamide was lower in patients receiving fluconazole [mean(SD) 2.4(0.71) versus 4.2(1.2) l/h/m2, p =.001]. In vitro studies were performed to characterize the interaction between fluconazole and cyclophosphamide in six human liver microsomes. The concentration of fluconazole required to reduce the production of 4-hydroxycyclophosphamide to 50% of control values (IC50) varied between 9 and 80 microM (median 38 microM). Further studies of the effect of fluconazole on 4-hydroxycyclophosphamide production in vivo are warranted to determine whether this interaction reduces the therapeutic effect of cyclophosphamide in clinical practice. (+info)
Multimodality therapy for locally advanced and limited stage IV breast cancer: the impact of effective non-cross-resistance late-consolidation chemotherapy.
To determine the effectiveness of non-cross-resistant late-consolidation chemotherapy in locally advanced breast cancer (LABC) and stage IV breast cancer, we review our experience with two regimens. Between 1985 and 1991, we enrolled 56 patients with LABC, who were treated with a doxorubicin-based adjuvant regimen, followed by a late-consolidation non-cross-resistant regimen containing methotrexate, 5-fluorouracil, cisplatin, and cyclophosphamide. Between 1985 and 1996, a total of 45 patients with limited stage IV breast cancer underwent surgical excision of all evaluable disease, making them metastatic (stage IV) with no evaluable disease. Surgery was followed by a doxorubicin-containing regimen and then a late-consolidation non-cross-resistant regimen, which was either methotrexate, 5-fluorouracil, cisplatinum, and cyclophosphamide or 5-fluorouracil, mitomycin, etoposide, and cisplatin. Twenty-four patients with limited bone metastases that were unresectable were treated with a doxorubicin-containing regimen, radiation therapy to all sites of disease, and then one of the two late non-cross-resistant regimens. With a median follow-up of 84 months, 78% of patients with LABC are alive, and 68% are free of disease. After a median follow-up of 44 months, 53% of patients with stage IV with no evaluable disease are alive and free of disease. The use of non-cross-resistant late-consolidation chemotherapy is an effective strategy in the treatment of patients with LABC and selected patients with limited stage IV breast cancer. (+info)
Can we cure indolent lymphomas?
The current consensus is that indolent lymphomas are incurable disorders. There are some indications that these malignancies are potentially curable. Indeed, not all indolent lymphomas are currently incurable. For example, patients with Ann Arbor stage I-II indolent lymphomas can experience long-term disease-free survival and probable cure. Also, from the available literature data, it seems that the achievement of a molecular complete remission is a desirable objective. Patients who achieve a persistently negative PCR state seldom relapse, whereas the opposite is true for persistently positive cases. In view of its excellent correlation with disease-free survival when examined serially in multiple blood or marrow samples, the PCR technique has the potential of providing a tumor marker that can be used as an early end point for clinical trials. By serving as an early surrogate end point, PCR could play an important role in expediting the development of new treatment strategies. Whether IFN is capable of increasing the molecular complete remission rate as measured by PCR is not known. However, it is clear that from the clinical standpoint, IFN has been able to increase 2-fold the length of remission in patients with advanced indolent lymphomas. In at least two studies, this has been associated with prolongation of survival. More intensive regimens such as alternating triple therapy, when used in combination with IFN, seem to have improved the quality of remissions as judged by the PCR assay. Finally, the site where the bcl-2 breakpoint occurs seems to have clinical significance. Those follicular lymphomas with germ-line bcl-2, in our experience, have behaved more aggressively than the others, and their failure-free survival seems different from the usual indolent lymphomas and more closely resembles the large cell lymphomas. Although the biological significance of this observation is not yet understood, this group might actually constitute a prognostically different subset with a more aggressive and perhaps more curable lymphoma. Whether the plateau observed in their failure-free survival curve will be maintained with more follow-up and whether they might be a curable subset remain to be determined. (+info)