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PubMed1985

Protective effect of testosterone or 5 beta-dihydrotestosterone pretreatment on CFU-E numbers in busulfan-treated rabbits.

Busulfan is known to damage hematological stem cells. On the other hand, numerous steroid hormones have a stimulating effect on hematopoiesis. We wished to find out whether steroids have a protective effect on hematopoiesis in the case of busulfan treatment. This possibility was tested in vitro in rabbit bone marrow cultures, with and without in vivo pretreatment, with regard to erythropoiesis. The stimulating effect of testosterone or 5 beta-dihydrotestosterone on the CFU-E number in rabbit bone marrow cultures was blocked in the presence of busulfan. When rabbits were pretreated with either steroid before the administration of busulfan, however, the reduction of the CFU-E number seen after busulfan therapy alone was compensated. These results indicate that testosterone and the nonandrogenic 5 beta-dihydrotestosterone provide some protective effect on erythroid precursor cells when administered with reference to the cell-cycle-dependent action of busulfan.

Animals↗
PubMed1990

The effect of hepatic enzyme inducers on busulfan neurotoxicity and myelotoxicity.

Anticonvulsants are commonly used empirically to prevent seizures in patients receiving high-dose busulfan in preparation for bone marrow transplantation. This study evaluates the effects of two anticonvulsants with enzyme-inductive properties, phenytoin and phenobarbital, and an enzyme inducer without anticonvulsant properties, Aroclor 1254, on the myelotoxicity and acute neurotoxicity of busulfan in a murine model. To assess the neuroprotective effects of these agents, we studied the effects of a single dose of 100 mg/kg i.p. busulfan, previously shown in this model to be uniformly lethal due to neurotoxicity. A significantly greater proportion of mice survived when pretreated with phenytoin or phenobarbital as compared with Aroclor 1254 pretreatment or an untreated control group. Busulfan myelotoxicity was studied in another group of mice treated with 135-150 mg/kg given in divided doses over 6 days. The proportion of animals surviving the otherwise myeloablative effects of this regimen were significantly improved by Aroclor 1254, high-dose phenytoin, and phenobarbital pretreatment. We conclude that anticonvulsants offer protection from the acute neurotoxicity of busulfan. However, these enzyme-inducing agents may reduce the myelosuppressive effects as well. These results suggest that an inducible enzyme system such as microsomal or glutathione S-transferases plays an important role in busulfan metabolism, warranting concern over concomitant administration of agents that either induce or inhibit these enzymes.

Animals↗
PubMed1994

Busulfan therapy of central nervous system xenografts in athymic mice.

We evaluated the antitumor activity of busulfan against a panel of tumor cell lines and xenografts in athymic nude mice derived from childhood high-grade glioma, adult high-grade glioma, ependymoma, and medulloblastoma. Busulfan displayed similar activity against a panel of four medulloblastoma cell lines (D283 Med, Daoy, D341 Med, and D425 Med) and four corresponding sublines with laboratory-generated or clinically acquired resistance to 4-hydroperoxycyclophosphamide [D283 Med (4-HCR), Daoy (4-HCR), D341 Med (4-HCR), and D458 Med] and cross-resistance to melphalan. This is consistent with a nearly total lack of cross-resistance of busulfan to 4-hydroperoxycyclophosphamide. Busulfan was active in the therapy of all but one of the subcutaneous xenografts tested, with growth delays ranging from 14.3 days in D612 EP to 58.4 days in D528 EP. Busulfan produced statistically significant increases in the median survival of mice bearing intracranial D456 MG (66%-90%), D612 EP (18%-33%), and D528 EP (89%) xenografts. These studies suggest that busulfan may be active against medulloblastomas, high-grade gliomas, and ependymomas as well as against cyclophosphamide-resistant neoplasms.

Animals↗
PubMed1997

Characterization of the mechanisms of busulfan resistance in a human glioblastoma multiforme xenograft.

Busulfan is an alkylating agent commonly used in the treatment of chronic myelogenous leukemia and in combination with cyclophosphamide in preparation for allogeneic bone marrow transplantation. Serial treatment of a childhood high-grade glioma xenograft (D-456 MG) with busulfan resulted in a busulfan-resistant xenograft, D-456 MG(BR). Cross-resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea was seen but not resistance to cyclophosphamide or CPT-11. Cytoplasmic levels of glutathione in D-456 MG(BR) were approximately one-half those found in D-456 MG. This depletion could not be explained by levels of glutathione-S-transferase, or by amplification, rearrangement, or increased levels of transcript of gamma-glutamylcysteine synthetase. Furthermore, depletion of glutathione in D-456 MG did not alter busulfan activity. Quantitation of busulfan levels in D-456 MG and D-456 MG(BR) xenografts following treatment of mice at the dose lethal to 10% of the animals demonstrated that significantly lower levels of drug were achieved in D-456 MG(BR). These studies suggest that alterations in drug transport or metabolism of busulfan may play a role in the resistance of D-456 MG(BR) to this alkylator.

Animals↗
PubMed1987

Effects of busulfan on murine spermatogenesis: cytotoxicity, sterility, sperm abnormalities, and dominant lethal mutations.

The alkylating agent busulfan (Myleran) adversely affects spermatogenesis in mammals. We treated male mice with single doses of busulfan in order to quantitate its cytotoxic action on spermatogonial cells for comparison with effects of other chemotherapeutic agents, to determine its long-term effects on fertility, and to assess its possible mutagenic action. Both stem cell and differentiating spermatogonia were killed and, at doses above 13 mg/kg, stem cell killing was more complete than that of differentiating spermatogonia. Azoospermia at 56 days after treatment, which is a result of stem cell killing, was achieved at doses of over 30 mg/kg; this dose is below the LD50 for animal survival, which was over 40 mg/kg. Busulfan is the only antineoplastic agent studied thus far that produces such extensive damage to stem, as opposed to differentiating, spermatogonia. The duration of sterility following busulfan treatment depended on the level of stem cell killing and varied according to quantitative predictions based on stem cell killing by other cytotoxic agents. The return of fertility after a sterile period did not occur unless testicular sperm count reached 15% of control levels. Dominant lethal mutations, measured for assessment of possible genetic damage, were not increased, suggesting that stem cells surviving treatment did not propagate a significant number of chromosomal aberrations. Sperm head abnormalities remained significantly increased at 44 weeks after busulfan treatment, however, the genetic implications of this observation are not clear. Thus, we conclude that single doses of busulfan can permanently sterilize mice at nonlethal doses and cause long-term morphological damage to sperm produced by surviving stem spermatogonia.

Alkylating Agents↗
PubMed1982

Residual injury to the hemopoietic microenvironment following sequential radiation and busulfan.

Our earlier studies in mice showed that sequential radiation and cyclophosphamide suppressed marrow stromal cells (MSC) and prevented local hemopoietic repopulation for several months. Because others have shown that busulfan administration caused marrow aplasia, we studied its ability, combined with radiation, to produce a persistent microenvironmental defect in mice. Intraperitoneal administration of four weekly doses of 20 mg/kg busulfan, starting one week after 1500 rad leg irradiation, produced a severe microenvironmental lesion for 6 months reflected by lack of repopulation in femoral marrow to greater than 50% of normal by MSC, hemopoietic stem cells (CFU-S), and granulocyte-macrophage precursors. Differential marrow cell counts revealed that precursors of hemopoietic cells were more profoundly affected than their progeny. Hemopoietic stem cells and MSC failed to recover in busulfan-treated mice at 6 months to the same extent as those treated with cyclophosphamide. In addition, the busulfan-treated mice had an excessive number of myeloid blast cells and a severe erythroid depletion suggesting that these animals were preleukemic. We conclude that: 1) sequential radiation and busulfan administration caused long-term microenvironmental damage reflected by incomplete repopulation of the femoral marrow and suppression of MSC, and 2) multiple courses of busulfan prevented hemopoietic repopulation longer than a similar regimen of cyclophosphamide.

Animals↗
PubMed1995

A gas-chromatographic assay method for busulfan with sensitivity for test dose therapeutic monitoring.

A gas-chromatographic assay method was developed and validated for determination of busulfan in human plasma for test dose therapeutic drug monitoring. Busulfan and the internal standard (1,6-bis-(methanesulfonyloxy)hexane) were extracted from plasma samples and derivatized with 2,3,5,6-tetrafluorothiophenol prior to gas chromatographic determination. The 63Ni electron-capture detector provided a limit of quantitation of 0.0100 micrograms ml-1 busulfan in plasma with a linear response over the concentration range 0.0100-0.400 micrograms ml-1. Extraction and derivatization yields were 85.3%-91.0% and greater than 95%, respectively. Assay specificity for busulfan in the presence of potential metabolites was demonstrated. Potentially co-administered drugs gave no response under the sample preparation and chromatographic conditions described for quantification of busulfan. The applicability of this assay to the individualization of busulfan therapy based on a 2 mg test dose is discussed.

Antineoplastic Agents, Alkylating↗
PubMed2004

Murine male germ cell apoptosis induced by busulfan treatment correlates with loss of c-kit-expression in a Fas/FasL- and p53-independent manner.

Male germ cell apoptosis has been extensively explored in rodents. In contrast, very little is known about the susceptibility of developing germ cells to apoptosis in response to busulfan treatment. Spontaneous apoptosis of germ cells is rarely observed in the adult mouse testis, but under the experimental conditions described here, busulfan-treated mice exhibited a marked increase in apoptosis and a decrease in testis weight. TdT-mediated dUTP-X nicked end labeling analysis indicates that at one week following busulfan treatment, apoptosis was confined mainly to spermatogonia, with lesser effects on spermatocytes. The percentage of apoptosis-positive tubules and the apoptotic cell index increased in a time-dependent manner. An immediate effect was observed in spermatogonia within one week of treatment, and in the following week, secondary effects were observed in spermatocytes. RT-PCR analysis showed that expression of the spermatogonia-specific markers c-kit and Stra 8 was reduced but that Gli I gene expression remained constant, which is indicative of primary apoptosis of differentiating type A spermatogonia. Three and four weeks after busulfan treatment, RAD51 and FasL expression decreased to nearly undetectable levels, indicating that meiotic spermatocytes and post-meiotic cells, respectively, were lost. The period of germ cell depletion did not coincide with increased p53 or Fas/FasL expression in the busulfan-treated testis, although p110Rb phosphorylation and PCNA expression were inhibited. These data suggest that increased depletion of male germ cells in the busulfan-treated mouse is mediated by loss of c-kit/SCF signaling but not by p53- or Fas/FasL-dependent mechanisms. Spermatogonial stem cells may be protected from cell death by modulating cell cycle signaling such that E2F-dependent protein expression, which is critical for G1 phase progression, is inhibited.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Busulfan clearance in renal failure and hemodialysis.

The impact of hemodialysis on the clearance of busulfan was determined in a patient with chronic renal failure undergoing autologous peripheral stem cell transplantation for non-Hodgkin's lymphoma. The extraction ratio for busulfan across the dialyzer was 0.530 +/- 0.026 at a blood flow of 400 ml/min, which corresponds to a hemodialysis clearance of 2.23 +/- 0.11 ml/min/kg body weight. Apparent oral clearance of busulfan without hemodialysis was 3.38 +/- 0.56 ml/min/kg. Thus, a 4 h hemodialysis session enhanced the apparent oral clearance of busulfan by 65%. We conclude that hemodialysis effectively removes busulfan from circulating blood, but a standard hemodialysis period (ie, 4 h) does not significantly alter busulfan exposure. Bone Marrow Transplantation(2000) 25, 201-203.

Administration, Oral↗
PubMed2003

In children and adolescents, the pharmacodynamics of high-dose busulfan is dependent on the second alkylating agent used in the combined regimen (melphalan or thiotepa).

A strong relationship has been demonstrated between high systemic exposure to busulfan and the occurrence of hepatic veno-occlusive disease (HVOD) after a busulfan-cyclophosphamide regimen (BU CY). We report a prospective study aimed at exploring the pharmacodynamics of high-dose busulfan combined with either melphalan (BU MEL) or thiotepa (BU TTP) followed by autologous stem cell transplantation in children and adolescents with a malignant solid tumor. Busulfan was given orally at a total dose of 600 mg m(-2). In all, 45 patients with a median age of 6.3 years were included in the study: 25 received BU MEL and 20 received BU TTP. The incidence of HVOD was 44% (CI 95% [23-65%]) in the BU MEL group and 25% (CI95% [9-49%]) in the BU TTP group. In the BU TTP group, patients who developed HVOD had a significantly higher AUC 0-6 h after the 13th dose (6201+/-607 h ng ml(-1)) than those who did not (5024+/-978 h ng ml(-1)) (P<0.05). In the BU MEL group, there was no difference in terms of systemic exposure to busulfan between patients who developed HVOD and those who did not. In conclusion, the guidelines established for monitoring BU CY cannot be extrapolated when busulfan is combined with another drug.

Adolescent↗
PubMed2007

F-ara-A pharmacokinetics during reduced-intensity conditioning therapy with fludarabine and busulfan.

Fludarabine is commonly used in combination with busulfan as part of conditioning regimens before allogeneic stem cell transplantation. So far, no data are available on busulfan-fludarabine drug interactions in transplant recipients. The pharmacokinetic (PK) properties of F-ara-A (9-beta-D-arabinosyl-2-fluoradenine) before and after application of busulfan were prospectively investigated in 16 patients with hematological malignancies. The conditioning regimen consisted of intravenous fludarabine 30 mg/m(2) over 30 min from day -6 to day -3, and oral busulfan given at 1 mg/kg every 6 h from day -5 to day -2. PK parameters of F-ara-A, derived from plasma and urine on day -6, -5, -4 and -3, were determined using high-performance liquid chromatography (HPLC). AUC, C(max), t(1/2), Cl(total) and V(SS) were 21.9 microMh, 3.5 microM, 13.0 h, 4.3 l/h/m(2), 60.0 l/m(2) on day -6 and 22.4 microMh, 3.5 microM, 14.0 h, 4.7 l/h/m(2), 69.0 l/m(2) on day -5 to (-2), respectively. Cl(renal) and the urine-recovery were 4.8 l/h, 43.7% of the fludarabine dose on day -6 and 3.9 l/h, 44.2% of the fludarabine dose on day -5 to (-2), respectively. There were no changes in PK parameters of fludarabine given before and after intake of busulfan. This implies that a clinically relevant busulfan-fludarabine drug interaction is unlikely.

Adult↗
PubMed1982

Hydroxyurea versus busulfan in the treatment of chronic myelogenous leukemia.

A retrospective analysis of 67 patients with chronic myelogenous leukemia treated with hydroxyurea (41 patients) and busulfan (26 patients) compared the effectiveness of treatment and resulting survival. After 4 days of treatment, the white blood count in the hydroxyurea group fell at a rate of 31% +/- 10% per day compared to 10% +/- 8% for the busulfan group. At 6 months, the hemoglobin was similar, but in the busulfan group, the white blood count was significantly lower (12,500 vs. 29,900) (p = greater than 0.03). The platelet count was lower (311,000 vs. 481,000) in the busulfan group; however, the difference was not significant. When treatment was discontinued because of progression of the disease, the hemoglobin and white blood counts for both groups were similar. The platelet count was higher in the hydroxyurea group (762,000 vs. 269,000) (p greater than 0.02). The duration of therapy for both groups was similar. The median survival was also similar (hydroxyurea = 51 months; busulfan = 45 months). Hydroxyurea was associated with less life-threatening toxicity. Hydroxyurea is as effective as busulfan in treating chronic myelogenous leukemia.

Actuarial Analysis↗
PubMed1988

Remission of chronic idiopathic myelofibrosis to busulfan treatment.

Three patients with chronic idiopathic myelofibrosis have responded to busulfan treatment with an excellent hematologic remission and reversal of myelofibrosis and myeloid metaplasia. Four months after busulfan therapy all three patients showed an improvement of hematocrit and hemoglobin and reduction of the number of leukoerythroblasts. Cellular bone marrow was re-established in two patients. A decrease of hepatomegaly and splenomegaly also occurred and was well correlated with the hematologic response. In one patient, when busulfan was discontinued for about 2 years after achieving an excellent remission, hematologic relapse was accompanied by increase of hepatomegaly and splenomegaly. When busulfan treatment was resumed, hematologic response and decrease of hepatomegaly and splenomegaly reoccurred. This observation has demonstrated the beneficial effect of busulfan in chronic idiopathic myelofibrosis; therefore, the role of busulfan in the management of this disease should be further investigated.

Aged↗
PubMed1992

Preclinical activity of hepsulfam and busulfan in solid human tumor xenografts and human bone marrow.

Hepsulfam (1,7-heptanediol disulfamate, NSC 329680) is a new antineoplastic alkanesulfonate agent which has demonstrated a broader preclinical activity than busulfan. The compound is currently undergoing clinical trials. We have studied the activity of hepsulfam and busulfan simultaneously in human tumor xenografts in vitro in a clonogenic assay and in vivo in tumor-bearing animals in order to assess the activity of both compounds in model systems of slowly growing malignancies. In a total of 37 different tumors of various histologies, both agents demonstrated broad spectrum in vitro activity. The median IC50 of hepsulfam and busulfan was determined as 0.93 and 3.31 micrograms/ml, respectively. At a concentration of 1.0 micrograms/ml, hepsulfam was active in eight of 37 tumors (22%) in the clonogenic assay, whereas busulfan effected inhibition of colony formation in one of 37 lines (3%). At the same concentration, however, hepsulfam demonstrated a clear in vitro toxicity to human bone marrow cells (CFU-GM) from healthy donors, whereas busulfan did not reveal a myelosuppressive effect. Evaluation of equitoxic concentrations in vitro revealed a higher activity of hepsulfam, especially in non-small cell lung cancer. In tumor-bearing nude mice, the approximate LD10 dose was determined as 150 mg/kg single bolus injection given i.p. on day 1 for both compounds. Hepsulfam demonstrated superior in vivo activity in a large cell lung cancer xenograft and a gastric carcinoma model. The preclinical activity of hepsulfam suggests a possible role of this compound in the treatment of solid human malignancies. However, the increased bone marrow toxicity of hepsulfam as compared with busulfan might be critical for further clinical application.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Therapeutic monitoring of busulfan in hematopoietic stem cell transplantation.

Busulfan is an alkylating agent commonly used to ablate marrow before hematopoietic stem cell transplantation. High levels have been shown to increase the chance for severe hepatic veno-occlusive disease, for which there is no treatment and which can be fatal. Low levels are associated with recurrence of chronic myeloid leukemia, whereas even lower levels are associated with graft rejection. The therapeutic window for busulfan is narrow and disease and graft-source dependent. Busulfan concentration in plasma is readily assayed by gas chromatography. In the authors' center, busulfan levels determined from the first dose of the drug are used to adjust the dose to that selected to achieve the desired therapeutic outcome by the third dose of the 16-dose regimen. Thus, turnaround time is less than 6 hours. Analytical and pharmacokinetic aspects of busulfan therapeutic monitoring are described. The cost of pharmacokinetically targeting busulfan concentration is < or = 1% of the cost of hematopoietic stem cell transplantation.

Adult↗
PubMed2004

A simple approximation for busulfan dose adjustment in adult patients undergoing bone marrow transplantation.

Busulfan is an alkylating agent used in preparative regimens before bone marrow transplantation (BMT). Busulfan concentrations in plasma, expressed as the area under the concentration-time curve (AUC), were reported to correlate with treatment outcome. Because busulfan is administered in 16 doses of 1 mg/kg every 6 hours for 4 days, the opportunities to "correct" the dose as a consequence of the measured AUC are limited to the 16-dosage protocol. In the present research busulfan pharmacokinetics were prospectively evaluated in 27 adult patients treated according to the above protocol by measuring the first, second, and fifth dose AUC. The pharmacokinetic analysis was based on a noncompartment model for extravascular absorption, but calculations according to a 1-compartment model gave similar results. A simple mathematical approximation allowed prediction of the AUC of the second dose from that of the first and the busulfan concentration at trough. Fifteen patients had the dose adjusted at the fourth dose to obtain an AUC within the "therapeutic window" of 950-1500 microM-min. This procedure was then validated by the measurement of the fifth dose AUC. It appears that this simple pocket calculator method allows a rapid evaluation of the need and the extent of dose adjustment and proved to be a valuable tool to improve busulfan administration in pre BMT treatment.

Adolescent↗
PubMed2006

Phase I trial of intrathecal spartaject busulfan in children with neoplastic meningitis: a Pediatric Brain Tumor Consortium Study (PBTC-004).

PURPOSE: A phase I trial of intrathecal Spartaject Busulfan (SuperGen, Inc., San Ramon, CA) was conducted in children with neoplastic meningitis following recurrent primary brain tumors to describe toxicities, estimate the maximum tolerated dose (MTD), and document evidence of responses to this agent. EXPERIMENTAL DESIGN: The continuous reassessment method was used to assign cohorts of patients to doses of intrathecal Spartaject Busulfan via an Ommaya reservoir and/or lumbar puncture twice weekly for 2 weeks followed by an assessment of toxicity and response. Patients with stable disease or an objective response continued to receive intrathecal Spartaject Busulfan plus systemic chemotherapy at regular intervals. Cerebrospinal fluid and blood were obtained for pharmacokinetic studies in patients with Ommaya reservoirs after the first dose of intrathecal Spartaject Busulfan. Seven evaluable patients were assigned to the starting dose of 5 mg, two patients to 7.5 mg, three patients to 10 mg, seven patients to 13 mg, and four patients to 17 mg. RESULTS: Between September 2000 and May 2003, 28 patients were enrolled in this study. Twenty-three patients (median age, 8.8 years; range, 2.5-19.5 years) were evaluable for estimating the MTD, and dose-limiting toxicities were observed in three and included grade 3 vomiting (n = 1 at 5 mg), grade 3 headache (n = 1 at 17 mg), and grade 3 arachnoiditis (n = 1 at 17 mg). Pharmacokinetic data showed that post-infusion concentrations of busulfan ranged from 50 to 150 microg/mL and declined to <1 microg/mL within 5 hours. CONCLUSIONS: Intrathecal Spartaject Busulfan was well tolerated in children with neoplastic meningitis from brain tumors, and the recommended dose for future phase II studies is 13 mg.

Adolescent↗
PubMed2000

Role of oxidative stress and glutathione in busulfan toxicity in cultured murine hepatocytes.

UNLABELLED: This study examines busulfan metabolism. Busulfan given in vivo or in vitro decreased hepatocyte glutathione (GSH) by 60 and 50%, respectively. In vitro, busulfan toxicity was prevented by glutathione S-transferase inhibitors or by antioxidants and led to increased production of oxidized GSH and thiobarbituric acid reactive substances. 'Rescue' from toxicity by GSH precursors was prevented by N,N-bis(2-chloroethyl)-N-nitrosourea (BCNU). Depletion of GSH exacerbated toxicity. In GSH-depleted hepatocytes, busulfan decreased GSH by 95% and BCNU did not prevent rescue by GSH precursors. CONCLUSIONS: (1) In hepatocytes with normal GSH: busulfan toxicity requires GSH conjugation, does not cause profound GSH depletion and is mediated by oxidative stress. We postulate that a GSH conjugate promotes oxidative stress. (2) In GSH-depleted hepatocytes: busulfan profoundly depletes GSH; toxicity is mediated by oxidative stress and is prevented by restoring GSH levels; cell death may be due to unopposed endogenous oxidative stress.

Alkylating Agents↗