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Dexamethasone-based regimens versus melphalan-prednisone for elderly multiple myeloma patients ineligible for high-dose therapy.

Dexamethasone alone increases life expectancy in patients with relapsed multiple myeloma (MM); however, no large randomized study has compared dexamethasone and dexamethasone-based regimens with standard melphalan-prednisone in newly diagnosed MM patients ineligible for high-dose therapy. In the Intergroupe Francophone du Myélome (IFM) 95-01 trial, 488 patients aged 65 to 75 years were randomized between 4 regimens of treatment: melphalan-prednisone, dexamethasone alone, melphalan-dexamethasone, and dexamethasone-interferon alpha. Response rates at 6 months (except for complete response) were significantly higher among patients receiving melphalan-dexamethasone, and progression-free survival was significantly better among patients receiving melphalan (P < .001, for both comparisons), but there was no difference in overall survival between the 4 treatment groups. Moreover, the morbidity associated with dexamethasone-based regimens was significantly higher than with melphalan-prednisone, especially for severe pyogenic infections in the melphalan-dexamethasone arm and hemorrhage, severe diabetes, and gastrointestinal and psychiatric complications in the dexamethasone arms. Overall, these results indicated that dexamethasone should not be routinely recommended as first-line treatment in elderly patients with MM. In the context of the IFM 95-01 trial, the standard melphalan-prednisone remained the best treatment choice when efficacy and patient comfort were both considered. These results might be useful in the context of future combinations with innovative drugs.

Aged↗

Kupffer cell-expressed membrane-bound TNF mediates melphalan hepatotoxicity via activation of both TNF receptors.

Isolated hepatic perfusion of nonresectable liver cancer using the combination of TNF and melphalan can be associated with a treatment-related hepatotoxicity. We investigated whether, apart from TNF, also melphalan is cytotoxic in primary murine liver cells in vitro and investigated mediators, mode of cell death, and cell types involved. Melphalan induced a caspase-dependent apoptosis in hepatocytes, which was not seen in liver cell preparations depleted of Kupffer cells. Neutralization of TNF prevented melphalan-induced apoptosis and liver cells derived from mice genetically deficient in either TNFR 1 or 2, but not from lpr mice lacking a functional CD95 receptor, were completely resistant. Cell-cell contact between hepatocytes and Kupffer cells was required for apoptosis to occur. Melphalan increased membrane-bound but not secreted TNF in Kupffer cells and inhibited recombinant TNF-alpha converting enzyme in vitro. Melphalan induced also severe hepatotoxicity in the isolated recirculating perfused mouse liver from wild-type mice but not from TNFR 1 or 2 knockout mice. In conclusion, this study shows that melphalan elicits membrane TNF on Kupffer cells due to inhibition of TNF processing and thereby initiates apoptosis of hepatocytes via obligatory activation of both TNFRs. The identification of this novel mechanism allows a causal understanding of melphalan-induced hepatotoxicity.

ADAM Proteins↗

Changes in glutathione content and resistance to anticancer agents in human stomach cancer cells induced by treatments with melphalan in vitro.

A clone of a human gastric carcinoma cell line was used to determine whether cells which had survived a treatment with Melphalan would express altered survival responses when treated again with this agent 1 week or more later. Cells were treated for 1 h each week with 2 micrograms/ml (99% lethal dose). After the first Melphalan treatment, the cells exhibited a 10-fold reduction in sensitivity to Melphalan. This was preceded by a 2-fold increase in intracellular glutathione content. By the end of 10 weekly treatments, the cells were 50 times more resistant than controls (based on changes in survival fractions). They also demonstrated collateral resistance to Actinomycin D, 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea, galactitol, and X-rays, but showed no change in sensitivity to 5-fluorouracil, bleomycin, and Adriamycin. The resistance to Melphalan was not reversible when treatment was withheld for 4 weeks on two different occasions. The results suggest that treatment with a high dose of Melphalan either selects an existing population of cells with a high GSH content or induces mutations leading to increased GSH content or both, and this results in the expression of greater Melphalan resistance at the time of other treatments. Furthermore, Melphalan treatment stimulates a 50% increase in GSH content in resistant cells in just 6 h, an 85% increase in 36 h, and a 150% increase in 72 h. L-Buthionine sulfoximine partially reversed the expression of resistance to Melphalan by inducing a 60% reduction in intracellular glutathione content.

Buthionine Sulfoximine↗

Binding and internalization of human immunoglobulin G conjugated with melphalan (K18) to human tumor cell lines.

The binding and internalization of melphalan-conjugated human immunoglobulin G (K18) to human tumor cell lines were studied using 14C-K18 (IgG conjugated with 14C-melphalan) and were compared with those of 14C-melphalan. K18 and melphalan dose-dependently bound to tumor cells, and the saturation binding analysis revealed a receptor-mediated binding of K18 but not of melphalan, to tumor cells. Intracellular distribution of 14C-K18 differed from that of 14C-melphalan, but a DNA unwinding experiment using a hydroxylapatite column showed that 14C-melphalan or 14C-K18 bound to DNA. These results suggest that after being bound to receptors K18 may be internalized in a macromolecular form and degraded into peptide binding melphalan. Moreover, the quantity of K18 that bound to 7 different human tumor cell lines was significantly larger than those that bound to lymphocytes of normal donors. These results suggest that K18 may be beneficial for cancer chemotherapy.

Antineoplastic Agents↗

Establishment of a melphalan-resistant rhabdomyosarcoma xenograft with cross-resistance to vincristine and enhanced sensitivity following buthionine sulfoximine-mediated glutathione depletion.

A melphalan-resistant human rhabdomyosarcoma xenograft, TE-671 MR, was established in athymic mice by serial melphalan treatment of the parent xenograft, TE-671, at the 10% lethal dosage (LD10); significant resistance was evident after ten passages of the tumor. TE-671 MR demonstrated a doubling time of 3.5 days and a latency period to 1000-mm3 tumors of 27.5 days. The glutathione level of TE-671 MR was 2.36 mumol/g tumor, wet weight, 2-fold higher than the parent line. The glutathione S-transferase activity of TE-671 MR was 117.8 mumol/min/mg protein, essentially unchanged from the parent line. Although TE-671 MR demonstrated cross-resistance to vincristine, dot blot analysis did not reveal an elevated expression of mdr1 mRNA in the resistant line. TE-671 MR demonstrated a 9.7-day growth delay following treatment with melphalan at the LD10 (compared to 20.9 days for the parent line). Treatment with L-buthionine-SR-sulfoximine (BSO) resulted in increased sensitivity to melphalan subsequently administered at 50% of the LD10 (melphalan alone, growth delays of 3.7 and 4.6 days in duplicate trials; melphalan plus BSO, growth delays of 7.2 and 9.8 days). Sensitivity to melphalan equal to that of the parent line TE-671 was not achieved, however. Treatment with BSO did not result in significantly enhanced sensitivity to subsequently administered vincristine (50% of the LD10) (vincristine alone, growth delays of 6.8 and 6.9 days in duplicate trials; vincristine plus BSO, growth delays of 10.9 and 7.5 days). These results suggest that generation of melphalan resistance may be associated with development of cross-resistance to vincristine; this resistance may be associated with (although not necessarily mediated by) glutathione elevation; this resistance may be partially overcome by BSO-mediated depletion of glutathione.

Animals↗

Influence of cytotoxic drugs on platelet functions and coagulation in vitro. IV. Melphalan.

Influence of melphalan on some platelet functions, plasmatic coagulation and fibrinolysis "in vitro" was investigated, using different concentrations of the drug (25, 50 and 250 mug/ml). The lowest concentration slightly inhibited adrenaline and/or collagen-induced platelet aggregation. Following the highest concentration of the drug, strong inhibition of aggregation was recorded, regardless of the inducer used. Melphalan was also shown to inhibit release of aggregating activity and release of platelet factor 4, as well as availability of platelet factor 3 and platelet acid phosphatase. The intensity of inhibition depended on both, melphalan concentration and the time of preincubation. In contrast to this, adhesion of platelets to glass slide was not found to be influenced by melphalan. Similarly, melphalan did not induce (in any concentration) loss of LDH from platelet cytoplasma, while triton X-100 or freezing and thawing of platelets caused significant increase of LDH activity. From coagulation tests studied, only thrombin time and reptilase time was found to be moderately prolonged in the presence of melphalan. Authors assumed that melphalan acts as a specific inhibitor of release reaction and can induce an acquired thrombocytopathy. The platelet membrane is not damaged by the drug, as was confirmed by the investigation of LDH activity. Influence on coagulation indicates some antithrombin effect of the drug. Although presented results were obtained in vitro, analogous changes in vivo could be suspected. Thus, impairement of platelet functions might play a part in haemorrhagic complications accompanying, in some cases, melphalan therapy.

Acid Phosphatase↗

Decreased immunoglobulin production by a human lymphoid cell line following melphalan treatment.

The effect of melphalan on immunoglobulin G (IgG) production by a human lymphoblastoid cell line (BF) was studied. The amount of secreted IgG and the percentage of cells containing cytoplasmic IgG were measured by immunoassay and cytofluorometry, respectively. Dose-response studied indicated that melphalan concentrations of 2 X 10(-8) M had no effect, while concentrations of 8 X 10(-7) M were totally toxic, after 72-hr exposures to the drug. Statistically significant, persistent, alterations in both synthesis and secretion of IgG by BF cells were observed following treatment for 72 hr with 4 X 10(-7) M melphalan, and there was an increase in population-doubling time from 24 to 72 hr in these drug-treated cells. The percentage of IgG-containing cells in melphalan-treated cultures was significantly decreased as compared to control cultures. IgG secretion was also decreased in these cultures, and the variation in IgG secretion as a function of cellular growth was significantly altered following melphalan treatment. Decreased IgG production following melphalan treatment may be related to altered cell cycle kinetics. Based on immunological analysis, there was no evident alteration in the IgG secreted by melphalan-treated cells, nor did melphalan treatment produce a cellular population lacking IgG entirely.

Aged↗

Evidence for carrier-mediated transport of melphalan by L5178Y lymphoblasts in vitro.

Mechanism of transport of the alkylating agent [14C]melphalan was investigated in L5178Y lymphoblasts in vitro. A time course of melphalan uptake was approximately linear for 5 to 10 min and thereafter entered a plateau region. Evidence that unidirectional influx of melphalan is carrier mediated was that uptake obeyed simple Michaelis-Menten kinetics, that it demonstrated chemical specificity, and that the cell/medium distribution ratio of drug decreased with increasing extracellular drug concentration. The kinetic parameters for melphalan transport consisted of a Km (mean +/- S.E.) of 1.53 +/- 0.18 X 10(-4) M and a transport capacity (Vmax) of 3.48 +/- 0.31 X 10(-17) mole/min/cell. Findings suggesting that transport was at least in part energy dependent and not simply a passive process were that drug uptake was temperature sensitive and sodium dependent. Analysis of cell sap constituents indicated the presence of intact drug within the cell. The percentage of radioactivity (mean +/- S.D.) found in the cell sap fraction was 95.8 +/- 2.2% of total cell activity, and 92.6 +/- 4.1% of this was trichloroacetic acid soluble. Thin-layer chromatography of the cell sap fraction and medium each revealed that the majority of radioactivity migrated as a single peak with an RF value identical with that obtained for free drug. The alkylating potential of intact drug complicated interpretation of the finding of apparent uphill transport against a concentration gradient. This observation, together with the relatively low cell-medium ratio (mean +/- S.D.) of 3.07 +/- 1.07, favors the concept that melphalan transport occurs by a facilitated diffusion process, although an active transport system has not been entirely excluded. The relative insensitivity of melphalan uptake to a wide range of metabolic inhibitors also suggests that transport is by a facilitated diffusion mechanism rather than an active process. Other alkylating agents and several amino acids including the L and D isomers of phenylalanine did not inhibit melphalan transport; thus a native substrate was not identified for the melphalan carrier and transport was by a mechanism separate from that of other alkylating agents.

Antimetabolites↗

A clinical and pharmacokinetic study of isolated limb perfusion with heat and melphalan for melanoma.

The pharmacokinetics of isolated limb perfusion were studied to see what melphalan concentrations were achieved and how effective the isolation was. Twenty-eight patients received 32 limb perfusions with heat and melphalan for locally recurrent or level V melanoma. Melphalan was given 0.75 mg/kg for axillary/popliteal or 1.2 mg/kg for femoral perfusions with heat (perfusate 42 degrees C, limb 40 degrees C) for 1 hour. Melphalan concentratives were measured by high-performance liquid chromatography in seven patients. Peak perfusate melphalan concentrations were 6.1 to 115 mg/ml, which was one to two logs higher than peak systemic concentratives of melphalan. Isolation of the perfusate circuit from the systemic circulation was better for axillary and popliteal perfusions than for femoral perfusions (P less than 0.05). Complete responses were seen in 81% of evaluable patients; long-term local control was achieved in most patients, although many developed hematogenous metastases. Toxicity included erythema and edema in all, mild leukopenia in two, neuropathy in two, and amputation was required in one patient. Improvements in surgical technique include regional anesthesia to reduce vasospasms and transcutaneous measurement of fluorescein to measure leak. Perfusion with heat and melphalan remains the treatment of choice for in-transit metastases from melanoma.

Chemotherapy, Cancer, Regional Perfusion↗

Differential enhancement of melphalan cytotoxicity in tumor and normal tissue by Fluosol-DA and oxygen breathing.

The addition of Fluosol-DA carbogen breathing to melphalan treatment of the FSa-IIC fibrosarcoma was assessed by tumor growth delay and cell survival assays. Melphalan (10 mg/kg) administered intraperitoneally (i.p.) was preceded by Fluosol-DA (0.3 ml) administered intravenously (i.v.) and followed by 1 hr of carbogen breathing; this resulted in a tumor growth delay of 9.5 +/- 1.4 days or an approximately 3-fold increase compared to melphalan alone. Melphalan produced about 1.7 logs of cell killing; neither carbogen breathing nor Fluosol-DA pretreatment altered the cell killing observed. There was a 10-fold increase in tumor-cell killing when Fluosol-DA was administered immediately prior to melphalan administration followed by carbogen breathing for 1 hr. Density gradient separation identified a population of denser FSa-IIC cells which showed increased sensitivity to melphalan after Fluosol-DA administration. There was no additional toxicity to bone marrow as measured by CFU-GM with the combination of melphalan/Fluosol-DA/O2 compared to melphalan alone.

Animals↗

Isolated lung perfusion with melphalan: pharmacokinetics and toxicity in a pig model.

BACKGROUND: In patients with unresectable lung cancer or pulmonary metastases, isolated lung perfusion (ILP) has been described as an alternative method to deliver high-dose chemotherapy to the lungs, thereby minimizing systemic toxicity. Pharmacokinetics of ILP have not been extensively investigated. Therefore, we studied the feasibility of ILP with melphalan in a pig model with emphasis on pharmacokinetics and acute lung damage. METHODS: Five pigs underwent ILP with melphalan. Blood and tissue samples were obtained for determination of melphalan levels. Tissue biopsies were taken for microscopic evaluation of lung damage. RESULTS: During ILP, no hemodynamic effects of importance were noted. No systemic leakage of melphalan was observed in any of the animals. Compared with normal lung tissue, microscopic examination of lung tissue after perfusion without melphalan showed pulmonary edema. Directly after melphalan perfusion additional hemorrhagic areas were seen; however, electron microscopy displayed no irreversible endothelial damage. CONCLUSION: This study on pigs proved to be a well reproducible model for ILP with melphalan. Pharmacokinetics show a safety profile with no systemic toxicity, which could justify further patient studies, necessary to determine its effect on pulmonary metastases in humans, especially in case of adjuvant therapy after surgical resection or in unresectable disease.

Animals↗

High dose melphalan in the treatment of advanced neuroblastoma: results of a randomised trial (ENSG-1) by the European Neuroblastoma Study Group.

BACKGROUND: High dose myeloablative chemotherapy ("megatherapy"), with haematopoietic stem cell support, is now widely used to consolidate response to induction chemotherapy in patients with advanced neuroblastoma. PROCEDURE: In this study (European Neuroblastoma Study Group, ENSG1), the value of melphalan myeloablative "megatherapy" was evaluated in a randomised, multi-centre trial. Between 1982 and 1985, 167 children with stages IV and III neuroblastoma (123 stage IV > 1 year old at diagnosis and 44 stage III and stage IV from 6 to 12 months old at diagnosis) were treated with oncovin, cisplatin, epipodophyllotoxin, and cyclophosphamide (OPEC) induction chemotherapy every 3 weeks. After surgical excision of primary tumour, the 90 patients (69% of the total) who achieved complete response (CR) or good partial response (GPR) were eligible for randomisation either to high dose melphalan (180 mg per square meter) with autologous bone marrow support or to no further treatment. RESULTS: Sixty-five (72%) of eligible children were actually randomised and 21 of these patients were surviving at time of this analysis, with median follow-up from randomisation of 14.3 years. Five year event-free survival (EFS) was 38% (95% confidence interval (CI) 21-54%) in the melphalan-treated group and 27% (95% CI 12-42%) in the "no-melphalan" group. This difference was not statistically significant (P = 0.08, log rank test) but for the 48 randomised stage IV patients aged >1 year at diagnosis outcome was significantly better in the melphalan-treated group-5 year EFS 33% versus 17% (P = 0.01, log rank test). CONCLUSIONS: In this trial, high dose melphalan improved the length of EFS and overall survival of children with stage IV neuroblastoma >1 year of age who achieved CR or GPR after OPEC induction therapy and surgery. Multi-agent myeloablative regimens are now widely used as consolidation therapy for children with stage IV disease and in those with other disease stages when the MYCN gene copy number in tumour cells is amplified. Because they are more toxic, complex, and costly these combination megatherapy regimens should be compared with single agent melphalan in randomised clinical trials.

Antineoplastic Agents, Alkylating↗

Enhancement of melphalan toxicity by octanol in ovarian adenocarcinoma cell lines: effects of altered cell-cell communication, glutathione levels, and plasma membrane fluidity.

A2780 and COLO-316 ovarian adenocarcinoma cell lines were exposed to 1.0 mM 1-octanol for 12 hr in order to evaluate the potential effects of inhibition of gap junction-mediated intercellular communication (GJIC) on cellular responses to the chemotherapeutic drug melphalan. Other cellular endpoints relevant to drug-resistance mechanisms which were monitored after treatments included cellular glutathione levels, glutathione S-transferase activity, mitochondrial membrane potential, and plasma membrane lipid mobility. In cells which were sensitive to melphalan, octanol enhanced melphalan toxicity in the GJIC-competent (A2780/S) but not GJIC-incompetent (COLO-316/S) sensitive cells. Although octanol increases plasma membrane lipid mobility in A2780/S and COLO-316/S, it appears that enhancement of A2780/S sensitivity to melphalan may be due to inhibition of GJIC. In melphalan-resistant cells (A2780/R and COLO-316/R), 1.0 mM octanol treatment for 12 hr combined with melphalan reversed the resistance of the cells to the drug. Therefore, alterations in cellular glutathione metabolism and effects on the plasma membrane in addition to uncoupling of GJIC may be involved in sensitizing communication-competent and communication-incompetent resistant cells because COLO-316/R lacks gap junction-mediated intercellular communication. Further, analysis of mitochondrial membrane potential provided an index of acquired drug resistance and the efficacy of melphalan and combined octanol/melphalan toxicity.

1-Octanol↗

The effect of food on oral melphalan absorption.

Fifteen patients receiving oral melphalan (4.2-5.3 mg/m2) for a variety of neoplastic disorders were studied. Ten patients received the drug on separate occasions, with and without a standardized breakfast. Eight of these patients also received an IV bolus dose (5 mg/m2) to determine bioavailability. Serial melphalan plasma samples were taken over 5 h after administration and assayed by high-performance liquid chromatography. The median area under the curve (AUC) when taken fasting was 179 (range 95-336) ng X h X ml-1, and when taken with food, 122 (47-227) ng X h X ml-1, the median reduction being 39% (P less than 0.01). In one patient, who died before completing the study, the drug was not detectable at all after being taken with food. In the eight patients who were also given IV melphalan, the median terminal melphalan half-life (57 min, range 38-71) was no different from its oral half-life [55 (27-104) min fasting; 55 (30-72) min with food] (P greater than 0.1). In these patients bioavailability was 85% (26-96)% when the drug was taken fasting and 58% (7-99)% when taken with food (P less than 0.025). Median clearance following IV administration was 362 ml/min/m2 (range 104-694). It was found that the melphalan level in a single plasma sample drawn 1.5 h after administration was highly predictive of oral melphalan AUC (rs = 0.915, P less than 0.1). This study suggests that to ensure optimum absorption of the drug, melphalan should not be taken with food.

Absorption↗

Comparison of the fed and fasting states on the absorption of melphalan in multiple myeloma.

Melphalan absorption was studied over three consecutive days in five patients with multiple myeloma. On 1 day melphalan (approximately 7 mg/m2 = 10-12 mg) was administered IV, on 1 day PO fasting, and on 1 day PO after a standard breakfast. The order was different for each patient to minimise trends that might affect absorption. Melphalan concentrations were determined by high-pressure liquid chromatography and fitted to biexponential equations by computer. The parameters of these equations were in broad agreement with previously published data, and melphalan absorption varied between patients. Considerable differences were observed in the melphalan concentration curves between the 'PO fed' and 'PO fasting' days: on the PO fed days the delay before absorption started was longer (1.1 +/- 0.5 h as against 0.3 +/- 0.1 h); peak plasma levels were one-third the value (65 +/- 15 ng/ml; 195 +/- 80 ng/ml) and occurred at twice the time after administration (2.8 +/- 0.8 h; 1.3 +/- 0.3 h); and areas under the curve were smaller 10.8 +/- 4.7 min X micrograms/ml; 23.8 +/- 13.8 min X micrograms/ml). There was a significant difference between the fraction of the dose of melphalan absorbed on the PO fed day (0.49 +/- 0.20) and on the PO fasting day (0.93 +/- 0.22), with P less than 0.005. This work suggests that melphalan should be taken first thing in the morning to obtain greatest absorption.

Absorption↗

Plasma melphalan and prednisolone concentrations during oral therapy for multiple myeloma.

Nine patients with myeloma were studied over 13 oral administrations of 10 mg melphalan and 5-10 mg prednisolone. Plasma melphalan concentrations were estimated by high-pressure liquid chromatography, prednisolone concentrations by quantitative thin-layer chromatography. The mean plasma half-life of unchanged melphalan was 0.9 +/- 0.5 (SD) h. The 'lag-time' before melphalan was detected in the plasma varied from 1 to 4 h, the mean peak concentration was 96 +/- 21 ng/ml, and the mean area under the plasma concentration by time curve was 160 +/- 78 ng h/ml. This variability was consistent with observations made elsewhere following much higher oral doses of melphalan and illustrates the relatively wide interindividual variability of absorption. Observations made in the same subjects on two separate occasions showed lower variability. The melphalan elimination rate was not significantly affected by moderate impairment of creatinine clearance (to 31 ml/min). Absorption of prednisolone in five of these patients was apparently normal and unaffected by concurrent administration of melphalan.

Adult↗

Renal function in the elimination of oral melphalan in patients with multiple myeloma.

Pharmacokinetic studies in 11 patients with multiple myeloma were undertaken on the first and last days of one course of chemotherapy. The drug was administered PO in single doses of 6-14 mg daily. Melphalan concentrations were determined by high-performance liquid chromatography. The interpatient variability of pharmacokinetic parameters noted by other authors was observed. Regression analysis showed a significant positive correlation between the elimination rate constant for melphalan and renal function (P = 0.003). The form of the line which describes the overall elimination rate constant for melphalan is given by the equation: Kel = 5.67 X 10(-3) + [4.90 X 10(-5) X GFR]. There was also a significant negative correlation between renal function and the area under the plasma melphalan concentration/time curve (P = 0.006). In vitro stability studies of melphalan in plasma at 37 degrees C and pharmacokinetic data suggest that hydrolysis and renal clearance are the major mechanisms of melphalan elimination. This work shows quantitatively the relationship between renal function and drug elimination and how the data may be used in predicting melphalan half-life from creatinine clearance.

Adult↗

Melphalan-induced toxicity in nude mice following pretreatment with buthionine sulfoximine.

Melphalan-induced toxicity in nude mice following pretreatment with a regimen of L-buthionine sulfoximine (BSO), previously shown to enhance the activity of this alkylating agent against rhabdomyosarcoma and glioma xenografts, was examined. Mice were pretreated with i.p. BSO (2.5 mmol/kg x 7 doses at 12-h intervals plus concomitant availability of a 20-mM solution in the drinking water) or vehicle prior to a single i.p. injection of melphalan (35.65 mg/m2). As compared with control animals who received no BSO pretreatment, mice pretreated with BSO lost weight prior to therapy with melphalan (6.9% weight loss vs 0.3% weight gain; P less than 0.005) and showed a greater mean nadir weight loss after melphalan (3.8% vs. 2.1%; P = 0.049). Treatment with melphalan was associated with histologic evidence of reversible gastrointestinal toxicity, reversible myelosuppression, and histologic evidence of acute renal tubular necrosis, with no differences being observed between mice that had been pretreated with BSO and those that had been pretreated with vehicle. No evidence of cardiac, hepatic, or skeletal muscle toxicity was found in melphalan-treated animals. These results suggest that treatment of nude mice with melphalan following BSO-mediated depletion of glutathione does not result in enhanced organ toxicity despite an increase in the antineoplastic activity of this alkylating agent.

Animals↗