Antineoplastic Mitoxantrone Monitor: A Sandwiched Mixed Matrix Membrane (MMM) Based on a Luminescent MOF-Hydrogel Hybrid.

A sandwiched mixed matrix membrane (MMM) based on a metal-organic framework-hydrogel hybrid exhibits eximious performance in the detection of mitoxantrone. Parts per billion-level sensitivity and good selectivity in serum among other analogous antineoplastics have been achieved. This flexible MMM can be used for point-of-care testing drugs in a biological medium.

[Repeated injection of mitoxantrone containing thermosensitive liposomes in rat induced ABC phenomenon].

To investigate whether accelerated blood clearance (ABC) phenomenon could be induced after repeated injection of mitoxantrone thermosensitive liposomes, LC-MS/MS and enzyme linked immunosorbent assay (ELISA) were used to measure the concentration of mitoxantrone and the anti-polyethylene glycol (PEG) IgM levels in rat plasma, separately. The drug was rapidly cleared away after the second administration. The anti-PEG IgM was detected after the first dose which was neutralized quickly after the second dose. It is proved that repeated administration of mitoxantrone thermosensitive liposomes in rat caused the ABC phenomenon.

Hydrogel-Coated SERS Microneedles for Drug Monitoring in Dermal Interstitial Fluid.

In vivo drug monitoring is crucial for evaluating the effectiveness and safety of drug treatment. Blood sampling and analysis is the current gold standard but needs professional skills and cannot meet the requirements of point-of-care testing. Dermal interstitial fluid (ISF) showed great potential to replace blood for in vivo drug monitoring; however, the detection was challenging, and the drug distribution behavior in ISF was still unclear until now. In this study, we proposed surface-enhanced Raman spectroscopy (SERS) microneedles (MNs) for the painless and real-time analysis of drugs in ISF after intravenous injection. Using methylene blue (MB) and mitoxantrone (MTO) as model drugs, the innovative core-satellite structured Au@Ag SERS substrate, hydrogel coating over the MNs, rendered sensitive and quantitative drug detection in ISF of mice within 10 min. Based on this technique, the pharmacokinetics of the two drugs in ISF was investigated and compared with those in blood, where the drugs were analyzed via liquid chromatography-mass spectrometry. It was found that the MB concentration in ISF and blood was comparable, whereas the concentration of MTO in ISF was 2-3 orders of magnitude lower than in blood. This work proposed an efficient tool for ISF drug monitoring. More importantly, it experimentally proved that the penetration ratio of blood to ISF was drug-dependent, providing insightful information into the potential of ISF as a blood alternative for in vivo drug detection.

Subchronic administration of mitoxantrone and the influence of enzyme inhibitors on its induced cardiotoxicity in mice: role of NRF-2/CYP2E1.

OBJECTIVE: Mitoxantrone (MTX)- induced cardiotoxicity is a clinical concern that is limiting its use. The aim of this paper, therefore, was to investigate the subchronic administration of MTX plus nonspecific/specific inhibitors of CYP450/2E1, to assess the extent of oxidative-induced injury by measuring levels of oxidative cardiac and injury biomarkers in mice and to evaluate the effects of CYP2E1 on caspase 3 activity and nuclear factor erythroid 2-related factor-2 (NRF-2). MATERIALS AND METHODS: Mice (n = 32) were divided into four treatment groups of eight: control, MTX, MTX + 4-methlypyrazole (4MP) and MTX + disulfiram (Disf). After 6 weeks of treatments, blood and heart samples were collected. RESULTS: Liquid chromatography-mass spectrometry (LCMS) analysis of MTX-treated plasma samples revealed several metabolites with different retention times. Cardiac antioxidant enzymes and creatine kinase (CK) levels were not significantly different among the groups. However, cardiac troponin and caspase 3 activity were significantly raised, with increased CYP2E1 expressions and reduced NRF-2 expression. Tissue damage was observed in all the treatment groups, including MTX, leading to the conclusion that MTX-induced cardiotoxicity was mediated by CYP2E1 activity, which initiated caspase 3 production, and decreased NRF-2 expression. CONCLUSIONS: Therefore, agents that inhibit CPY2E1 expression might attenuate MTX-induced cardiotoxicity by increasing NRF-2 expression.

Regulation of gene expression in brain tissues of rats repeatedly treated by the highly abused opioid agonist, oxycodone: microarray profiling and gene mapping analysis.

Although oxycodone is the most often used opioid agonist, it remains one of the most understudied drugs. We used microarray analysis to better understand the global changes in gene expression in brain tissues of rats repeatedly treated with oxycodone. Many genes were significantly regulated by oxycodone (e.g., Fkbp5, Per2, Rt1.Dalpha, Slc16a1, and Abcg2). Validation of the microarray data by quantitative real-time-polymerase chain reaction (Q-PCR) indicated that there was a strong significant correlation (r = 0.979, p < 0.0000001) between the Q-PCR and the microarray data. Using MetaCore (a computational platform), many biological processes were identified [e.g., organic anion transport (p = 7.251 x 10(-4)) and regulation of immune response (p = 5.090 x 10(-4))]. Among the regulated genes, Abcg2 mRNA was up-regulated by 2.1-fold, which was further confirmed by immunoblotting (1.8-fold up-regulation). Testing the Abcg2 affinity status of oxycodone using an Abcg2 ATPase assay suggests that oxycodone behaves as an Abcg2 substrate only at higher concentrations (> or = 500 microM). Furthermore, brain uptake studies demonstrated that oxycodone-induced Abcg2 up-regulation resulted in a significant (p < 0.05) decrease (approximately 2-fold) in brain/plasma ratios of mitoxantrone. These results highlight markers/mediators of neuronal responses and identify regulatory pathways involved in the pharmacological action of oxycodone. These results also identify genes that potentially modulate tolerance, dependence, immune response, and drug-drug interactions. Finally, our findings suggest that oxycodone-induced up-regulation of Abcg2 enhanced the efflux of the Abcg2 substrate, mitoxantrone, limiting its brain accumulation and resulting in an undesirable drug-drug interaction. Extrapolating these results to other Abcg2 substrates (e.g., daunorubicin and doxorubicin) indicates that the brain uptake of these agents may be affected if they are administered concomitantly with oxycodone.

Pilot study comparing serum chemotherapy levels after intra-arterial and intravenous administration in dogs with naturally occurring urinary tract tumors.

The proposed advantages of intra-arterial chemotherapy (IAC) are based on the premises of local dose escalation to the tumor and reduced availability of systemic drugs. There is a lack of objective pharmacokinetic data to confirm the advantage of IAC in dogs with naturally occurring urogenital tumors. The objective of this study was to determine if IAC administration in urogenital tumors would result in decreased systemic drug exposure when compared to intravenous routes. Twenty-two dogs with naturally occurring urogenital tumors were enrolled in this prospective case-controlled study. Mitoxantrone, doxorubicin, or carboplatin were administered by IAC and intravenous routes [intravenous awake (intravenous chemotherapy - IVC) and under general anesthesia (IVGAC)] 3 weeks apart. Serum assays were used to determine the extent of systemic drug exposure. Dose-normalized peak systemic serum concentration (Cmax) and area under the serum drug concentration-time curve (AUC) were used to quantify systemic exposure. A total of 26 mitoxantrone treatments were administered to 10 dogs. While there was no significant difference in Cmax, the AUC was significantly lower after IAC compared with IVGAC. Ten doxorubicin treatments were administered to 5 dogs. There were no significant differences in Cmax or AUC. A total of 14 carboplatin treatments were administered to 7 dogs. The Cmax was significantly lower for IAC compared to IVC, while the AUC values were equivocal. This study demonstrates certain lower serum values may be achieved after IAC delivery of carboplatin and mitoxantrone. These chemotherapy agents may have a preferred pharmacological profile for regional chemotherapy delivery in dogs with urogenital tumors.

Les avantages proposés de la chimiothérapie intra-artérielle (CIA) sont basés sur les prémisses d'une escalade de la dose locale à la tumeur et d'une disponibilité réduite des drogues systémiques. Il y a un manque de données pharmacocinétiques objectives pour confirmer l'avantage de l'administration de CIA chez les chiens avec des tumeurs urogénitales se produisant naturellement. L'objectif de la présente étude était de déterminer si l'administration de CIA lors de tumeurs urogénitales résulterait en une diminution de l'exposition systémique aux drogues lorsque comparé aux voies intraveineuses. Vingt-deux chiens avec des tumeurs urogénitales d'occurrence naturelle participèrent à cette étude cas-témoin prospective. De la mitoxantrone, de la doxorubicine, ou de la carboplatine furent administrées par CIA et voies intraveineuses [intraveineuse éveillée (chimiothérapie intraveineuse ­ CIV) et sous anesthésie générale (CIVAG)] à 3 sem d'intervalle. Des analyses du sérum furent utilisées afin de déterminer l'étendue de l'exposition systémique aux drogues. Le pic de la concentration sérique systémique normalisé pour la dose (Cmax) et la surface sous la courbe de la concentration sérique de la drogue-temps (SSC) furent utilisés pour quantifier l'exposition systémique. Un total de 26 traitements à la mitoxantrone fut administré à 10 chiens. Bien qu'il n'y ait pas de différence significative dans le Cmax, la SSC était significativement plus basse après la CIA comparativement à la CIVAG. Dix traitements de doxorubicine furent administrés à cinq chiens. Il n'y avait pas de différence significative dans le Cmax ou ls SSC. Un total de 14 traitements de carboplatine fut administré à sept chiens. Le Cmax était significativement plus bas pour la CIA comparativement à la CIV, alors que les valeurs de SSC étaient équivoques. Cette étude démontre que certaines valeurs sériques plus faibles peuvent être obtenues après CIA avec la carboplatine et la mitoxantrone. Ces agents de chimiothérapie pourraient avoir un profil pharmacologique préférentiel pour livraison régionale de chimiothérapie chez les chiens avec des tumeurs urogénitales.(Traduit par Docteur Serge Messier).

Pharmacokinetics, distribution and anti-tumor efficacy of liposomal mitoxantrone modified with a luteinizing hormone-releasing hormone receptor-specific peptide.

BACKGROUND: A previous study developed a novel luteinizing hormone-releasing hormone (LHRH) receptor-targeted liposome. The aim of this study was to further assess the pharmacokinetics, biodistribution, and anti-tumor efficacy of LHRH receptor-targeted liposomes loaded with the anticancer drug mitoxantrone (MTO). METHODS: Plasma and tissue distribution profiles of LHRH receptor-targeted MTO-loaded liposomes (LHRH-MTO-LIPs) were quantified in healthy mice or a xenograft tumor nude mouse model of MCF-7 breast cancer, and were compared with non-targeted liposomes and a free-drug solution. RESULTS: The LHRH-MTO-LIPs demonstrated a superior pharmacokinetic profile relative to free MTO. The first target site of accumulation is the kidney, followed by the liver, and then the tumor; maximal tumor accumulation occurs at 4 h post-administration. Moreover, the LHRH-MTO-LIPs exhibited enhanced inhibition of MCF-7 breast cancer cell growth in vivo compared with non-targeted MTO-loaded liposomes (MTO-LIPs) and free MTO. CONCLUSION: The novel LHRH receptor-targeted liposome may become a viable platform for the future targeted treatment of cancer.

Exposure-Response Analysis of Alvocidib (Flavopiridol) Treatment by Bolus or Hybrid Administration in Newly Diagnosed or Relapsed/Refractory Acute Leukemia Patients.

Purpose: To elucidate any differences in the exposure-response of alvocidib (flavopiridol) given by 1-hour bolus or a hybrid schedule (30-minute bolus followed by a 4-hour infusion) using a flavopiridol/cytosine arabinoside/mitoxantrone sequential protocol (FLAM) in patients with acute leukemia. The hybrid schedule was devised to be pharmacologically superior in chronic leukemia based on unbound exposure.Experimental Design: Data from 129 patients in three FLAM studies were used for pharmacokinetic/pharmacodynamic modeling. Newly diagnosed (62%) or relapsed/refractory (38%) patients were treated by bolus (43%) or hybrid schedule (57%). Total and unbound flavopiridol concentrations were fit using nonlinear mixed-effect population pharmacokinetic methodologies. Exposure-response relationships using unbound flavopiridol AUC were explored using recursive partitioning.Results: Flavopiridol pharmacokinetic parameters were estimated using a two-compartment model. No pharmacokinetic covariates were identified. Flavopiridol fraction unbound was 10.9% and not different between schedules. Partitioning found no association between dosing schedule and clinical response. Clinical response was associated with AUC ≥ 780 h*ng/mL for newly diagnosed patients and AUC ≥ 1,690 h*ng/mL for relapsed/refractory patients. Higher exposures were not associated with increases in severe adverse events (≥ grade 3).Conclusions: Pharmacokinetic modeling showed no difference in flavopiridol plasma protein binding for bolus versus hybrid dosing. Further trials in newly diagnosed patients with acute leukemia should utilize the bolus FLAM regimen at the MTD of 50 mg/m2/day. Trials in relapsed/refractory patients should use the hybrid dosing schedule at the MTD (30/60 mg/m2/day) to achieve the higher exposures required for maximal efficacy in this population. Clin Cancer Res; 23(14); 3592-600. ©2017 AACR.

Role of breast cancer resistance protein in the bioavailability and fetal penetration of topotecan.

BACKGROUND AND METHODS: Breast cancer resistance protein (BCRP/MXR/ABCP) is a multidrug-resistance protein that is a member of the adenosine triphosphate-binding cassette family of drug transporters. BCRP can render tumor cells resistant to the anticancer drugs topotecan, mitoxantrone, doxorubicin, and daunorubicin. To investigate the physiologic role of BCRP, we used polarized mammalian cell lines to determine the direction of BCRP drug transport. We also used the BCRP inhibitor GF120918 to assess the role of BCRP in protecting mice against xenobiotic drugs. Bcrp1, the murine homologue of BCRP, was expressed in the polarized mammalian cell lines LLC-PK1 and MDCK-II, and the direction of Bcrp1-mediated transport of topotecan and mitoxantrone was determined. To avoid the confounding drug transport provided by P-glycoprotein (P-gp), the roles of Bcrp1 in the bioavailability of topotecan and the effect of GF120918 were studied in both wild-type and P-gp-deficient mice and their fetuses. RESULTS: Bcrp1 mediated apically directed transport of drugs in polarized cell lines. When both topotecan and GF120918 were administered orally, the bioavailability (i.e., the extent to which a drug becomes available to a target tissue after administration) of topotecan in plasma was dramatically increased in P-gp-deficient mice (greater than sixfold) and wild-type mice (greater than ninefold), compared with the control (i.e., vehicle-treated) mice. Furthermore, treatment with GF120918 decreased plasma clearance and hepatobiliary excretion of topotecan and increased (re-)uptake by the small intestine. In pregnant GF120918-treated, P-gp-deficient mice, relative fetal penetration of topotecan was twofold higher than that in pregnant vehicle-treated mice, suggesting a function for BCRP in the maternal-fetal barrier of the placenta. CONCLUSIONS: Bcrp1 mediates apically directed drug transport, appears to reduce drug bioavailability, and protects fetuses against drugs. We propose that strategic application of BCRP inhibitors may thus lead to more effective oral chemotherapy with topotecan or other BCRP substrate drugs.

Plasma and cellular pharmacokinetics of mitoxantrone in high-dose chemotherapeutic regimen for refractory lymphomas.

We have studied the plasma and peripheral leukocyte pharmacokinetics of mitoxantrone associated, in a high-dose regimen, with cyclophosphamide, carmustine, and etoposide in patients with refractory lymphoma undergoing autologous bone marrow transplantation. Nineteen patients with refractory lymphoma were involved in a clinical trial with escalated doses (15-90 mg/m2) of mitoxantrone administered by 30-min i.v. infusion 8 days before an autologous bone marrow transfusion. Mitoxantrone was measured by high-performance liquid chromatography in plasma and peripheral lymphocytes. The plasma pharmacokinetics of mitoxantrone was linear between 15 and 90 mg/m2: total body clearance (19.3 +/- 6.2 liter/h/m2) and volume of distribution at steady state (486 +/- 254 liter/m2) were not altered by increasing the dose. The exposure of bone marrow transplant to the plasma residual concentration of mitoxantrone was correlated with the limiting hematological toxicity of the regimen (P < 0.001). At all times, the mitoxantrone concentration in peripheral cells was much higher than in plasma and was retained at a constantly high concentration level. Whereas cellular versus plasma maximum concentration ratio was near 1, the area under the concentration +/- time curve ratio reached 100, suggesting a long elimination half-life from cells. Plasma and cellular pharmacokinetics data of mitoxantrone reinforce the idea that this drug is a good candidate for high-dose chemotherapy regimen.

Characterization of the fluorescence of the antitumor agent, mitoxantrone.

Studies have been conducted on the absorption, fluorescence excitation and fluorescence emission of mitoxantrone, an important antineoplastic agent. Mitoxantrone has been found to fluoresce with excitation maxima at 610 and 660 nm and emission maximum at 685 nm. Further characterizations of the fluorescence were undertaken to study its usefulness in biological studies. Mitoxantrone fluorescence intensity is altered by pH and the emission spectrum is red-shifted by DNA. Furthermore, the fluorescence polarization is enhanced by DNA, confirming the binding of the antitumor agent to DNA. The fluorescence spectra are slightly modified by changes in ionic strength and the addition of albumin. Data establishing the usefulness of fluorescence to measure serum concentrations in the range of 0.0 to 100 nM are presented. Such determinations can distinguish serum mitoxantrone from its non-fluorescent primary metabolite.

A phase I pharmacokinetic study of 21-day continuous infusion mitoxantrone.

A phase I study of mitoxantrone given as a continuous infusion for 21 days using a venous access port and a portable pump was performed. The first dose step was 0.3 mg/m2/d for 21 days. Courses were repeated every 6 weeks. Dose increment per step was 0.1 mg/m2/d in the first three dose steps and 0.2 mg/m2/d in the latter dose steps. Twenty-five patients entered the study and received a total of 50 courses, with a median of two courses (range, one to five). Up to 0.5 mg/m2/d, no toxicity (according to the World Health Organization [WHO] criteria) occurred. At 0.7 mg/m2/d, one patient experienced grade 2 leukocytopenia and at the 0.9 mg/m2/d dose step, one patient experienced grade 2 leukocytopenia, grade 1 thrombocytopenia, and grade 1 hair loss. At 1.1 mg/m2/d, two of six patients had grade 3 leukocytopenia, and in one patient treatment was discontinued after two days because of myocardial infarction. In both patients receiving 1.3 mg/m2/d, treatment was discontinued after 2 weeks because of grade 3 leukocytopenia. Three patients at the 1.1 mg/m2/d, dose step and two patients at the 1.3 mg/m2/d dose step experienced some nausea in the last week of the infusion period. One patient developed subclavian vein thrombosis. No infectious complications occurred. Pharmacokinetic studies were performed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Plasma steady-state was reached after 35 hours. During steady-state there was a linear relationship between the mitoxantrone dose administered and the level of mitoxantrone in plasma (r = .93, P less than .005). The mitoxantrone level in leukocytes increased significantly during the infusion period at the 0.9 mg/m2, the 1.1 mg/m2, and the 1.3 mg/m2 dose steps. The area under the curve (AUC) in leukocytes was higher with continuous infusion of 1.1 mg/m2/d for 21 days compared with bolus injection of 12 mg/m2. Mitoxantrone could be detected in plasma for at least five days after the end of the 21-day infusion period and in leukocytes for at least 14 days. Continuous infusion mitoxantrone may increase intracellular drug uptake as expressed by intracellular AUC. We recommend a dose of 1.1 mg/m2/d for 3 weeks for evaluation of antitumor efficacy in phase II studies.

Separation of liposome-entrapped mitoxantrone from nonliposomal mitoxantrone in plasma: pharmacokinetics in mice.

A method is described for quantification of the liposomal and nonliposomal forms of mitoxantrone (MTO) in mouse plasma after intravenous administration of liposome-entrapped MTO Easy-to-Use (LEM-ETU) formulation. This is based on the property of liposome-entrapped MTO (LEM) to pass through reversed-phase C(18) silica gel cartridges, while nonliposomal MTO or free MTO is retained with strong hydrophobicity and later is eluted with acidic methanol. Extraction of LEM and free MTO from plasma is performed in two steps. This technique is rapid and sensitive and can be used for a large series of sample preparation. The plasma samples are found stable after one freeze-thaw cycle. The recovery of MTO, as well as the precision, linearity, and accuracy of the method for both free and liposomal MTO, appears satisfactory for pharmacokinetic studies. The pharmacokinetic results in mice show a sustained release of MTO from LEM-ETU.

New aspects on the pharmacokinetics of mitoxantrone and its two major metabolites.

In spite of its broad clinical application in the treatment of malignant disorders, the pharmacokinetics of mitoxantrone are still not fully understood and warrant further investigation. Information is also limited about interindividual differences in the plasma AUC infinity (area-under-the-curve concentration to time infinity) and renal elimination of mitoxantrone and its main metabolites, mono- and dicarboxylic acid. In the present study, the plasma concentration of mitoxantrone was measured by HPLC during 120 h after the end of a 30-min infusion of 10 mg/m2 in 18 patients undergoing combination therapy with mitoxantrone and high-dose cytosine arabinoside for acute myeloid leukemia. Plasma kinetics and renal elimination of mono- and dicarboxylic acid were analyzed in addition in eight of these patients, and in five cases with chronic lymphocytic leukemia receiving a 30-min infusion of 5 mg/m2 mitoxantrone weekly for 3 consecutive weeks. Fitting the results to a three compartment model, a substantial interindividual variation was observed for plasma and urine pharmacokinetics. Plasma AUC infinity for mitoxantrone differed approximately 13-fold between individual patients and varied between 80-1030 ngh/ml. The corresponding values for mono- and dicarboxylic acid ranged from 23-147 ngh/ml and 51-471 ngh/ml, respectively. The median terminal half-life for mitoxantrone was similar to that of the mono- and dicarboxylic acid and was 75 h. Cumulative renal elimination ranged from 670-1950 micrograms for mitoxantrone, from 366-852 micrograms for monocarboxylic acid, and from 792-3420 micrograms for dicarboxylic acid. Renal clearance of mitoxantrone reached a median level of 69 ml/min and for the total plasma clearance a median of 1136 ml/min was found. The corresponding values for the mono- and dicarboxymetabolites were 57 and 67 ml/min. In contrast to the great interindividual differences in pharmacokinetic results, a low intraindividual variability was observed upon repeated determinations of renal elimination of mitoxantrone and its metabolites at weekly intervals in five patients. These data provide new insights into the pharmacokinetic of mitoxantrone and its main metabolites revealing substantial differences in drug metabolism and elimination between individual patients. Further studies are needed to explore the potential impact on response and/or toxicity and the requirement of a pharmacokinetic directed adjustment of drug dosage in clinical trials.

Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia.

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

Plasma membrane targeting by short chain sphingolipids inserted in liposomes improves anti-tumor activity of mitoxantrone in an orthotopic breast carcinoma xenograft model.

Mitoxantrone (MTO) is clinically used for treatment of various types of cancers providing an alternative for similarly active, but more toxic chemotherapeutic drugs such as anthracyclines. To further decrease its toxicity MTO was encapsulated into liposomes. Although liposomal drugs can accumulate in target tumor tissue, they still face the plasma membrane barrier for effective intracellular delivery. Aiming to improve MTO tumor cell availability, we used short chain lipids to target and modulate the tumor cell membrane, promoting MTO plasma membrane traversal. MTO was encapsulated in liposomes containing the short chain sphingolipid (SCS), C8-Glucosylceramide (C8-GluCer) or C8-Galactosylceramide (C8-GalCer) in their bilayer. These new SCS-liposomes containing MTO (SCS-MTOL) were tested in vivo for tolerability, pharmacokinetics, biodistribution, tumor drug delivery by intravital microscopy and efficacy, and compared to standard MTO liposomes (MTOL) and free MTO. Liposomal encapsulation decreased MTO toxicity and allowed administration of higher drug doses. SCS-MTOL displayed increased clearance and lower skin accumulation compared to standard MTOL. Intratumoral liposomal drug delivery was heterogeneous and rather limited in hypoxic tumor areas, yet SCS-MTOL improved intracellular drug uptake in comparison with MTOL. The increased MTO availability correlated well with the improved antitumor activity of SCS-MTOL in a MDAMB-231 breast carcinoma model. Multiple dosing of liposomal MTO strongly delayed tumor growth compared to free MTO and prolonged mouse survival, whereas among the liposomal MTO treatments, C8-GluCer-MTOL was most effective. Targeting plasma membranes with SCS improved MTO tumor availability and thereby therapeutic activity and represents a promising approach to improve MTO-based chemotherapy.

Phase I/II pharmacokinetic study of mitoxantrone by continuous venous infusion in patients with solid tumours and lymphoproliferative diseases.

Phase I and pharmacokinetic studies were performed in order to evaluate the maximum tolerated dose and the efficiency of 120 h continuous venous infusion (CVI) of mitoxantrone. 25 patients suffering from either metastatic solid tumour or refractory lymphoproliferative disease were included in the study. The starting dose was 2 mg/m2 per day and was increased by a 0.2 mg/m2 per day step dose. The main toxicity observed was leukopenia which became limiting in more than 50% of the patients receiving 2.4 mg/m2 per day (12 mg/m2 over a 120 h period); this dose was defined as the maximal tolerated dose in these pretreated patients. One partial response and three stable diseases were observed. A plasma plateau concentration of mitoxantrone (2.13 [S.D. 0.54] micrograms/1 at 2 mg/m2 per day, 2.56 [1.32] micrograms/1 at 2.2 per day and 3.46 [1.32] micrograms/l at 2.4 mg/m2 per day) was reached within 24-48 h. It was linearly related to the administered dose. The mean plasma clearance of mitoxantrone was 27.8 [14.2] l/h/m2 and the volume of distribution of the beta phase averaged 2327 [2125] l/m2. An inverse relationship was established between the mitoxantrone clearance and the degree of hematologic toxicity. This 120 h CVI mitoxantrone schedule was safe and could be repeated every 3 weeks in an outpatient setting. The relationship between mitoxantrone clearance and the drug related haematotoxicity could be used for an individual dose adjustment.

Development of a sensitive monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for mitozantrone.

A mouse monoclonal antibody (NO-1) with specificity for the anti-cancer drug mitozantrone (MZ) (Novantrone) was produced by immunization of a BALB/c mouse with mitozantrone-keyhole limpet haemocyanin (MZ-KLH) conjugate. When used in an indirect competitive enzyme-linked immunosorbent assay (ELISA), NO-1 permitted the accurate and reproducible detection of between 0.25-50 ng/ml of MZ in pooled human serum, the standard curve obtained within this range being virtually linear. The assay demonstrated good reproducibility with intra-assay coefficients of variation (CV) of between 1.41% and 7.02% and an inter-assay CV of 3.45%. Regression analysis of levels of MZ detected by ELISA vs. the actual amounts added to pooled human serum gave a very good correlation coefficient of r = 0.995. NO-1 showed no cross-reactivity with either bisantrene or daunorubicin. A simple pharmacokinetic study was undertaken in rabbits given MZ intravenously at a dose of 0.5 mg/kg of body weight. Levels of MZ in rabbit serum measured with the assay ranged between 82 and 170 ng/ml for rabbits 1 and 2, respectively at 15 min falling to 1.25 ng/ml by 48 h for rabbit 1 and falling to undetectable levels by 120 h for rabbit 2.

Intracellular concentrations of mitoxantrone in leukemic cells in vitro vs in vivo.

The aim of this study was to determine the intracellular pharmacokinetics of mitoxantrone in vivo and to use these results to establish how leukemic cells should be incubated to perform clinically relevant in vitro studies of this drug. Blood samples were obtained from 11 patients with acute nonlymphoblastic leukemia at certain intervals up to 20 h after the infusion of mitoxantrone 12 mg/m2. Plasma and leukemic cells were separated and the drug concentrations were determined with HPLC. Before treatment, leukemic cells from 12 patients were incubated with 0.02, 0.05, 0.1, 0.2 and 1.0 microM mitoxantrone for 1-4 h and thereafter cultured in suspension culture for 20 h; during this time cell samples were taken at certain intervals for drug determination. In cells incubated with 0.05 and 0.2 microM mitoxantrone the cytotoxic effect was measured with the DiSC assay after cultivation for 4-5 days. In vivo, the intracellular levels exceeded the plasma concentrations already at the end of infusion and after 2 h the intracellular concentrations were 200-300 times higher than in plasma. In vitro, the intracellular steady state level of mitoxantrone was reached after 1-2 h and there was a pronounced intracellular retention even after 20 h culture in drug-free medium. Incubation with 0.05 microM during 1 h gave intracellular concentrations of mitoxantrone similar to those achieved in vivo. This incubation concentration gave a mean cytotoxic effect of 53% living cells measured with the DiSC assay, which gives good possibilities to discriminate between mitoxantrone-sensitive and unsensitive cells. We believe that exposing leukemic cells in vitro for in vivo mimicking mitoxantrone concentrations could increase the clinical relevance of predictive assays.

Clinical pharmacokinetics of mitoxantrone in hyperthermic, isolated perfusion of the leg.

The clinical pharmacokinetics of mitoxantrone in hyperthermic, isolated perfusion of the leg were studied in five patients exhibiting solitary, localized malignant melanoma. Mitoxantrone was given as four 1-min infusions at 15-min intervals into the arterial line of the perfusion system at a total dose of up to 14 mg/m2. The mean half-lives for mitoxantrone in the blood circulation of the leg were: t1/2 alpha (distribution phase), 25.5 s, and t1/2 beta (elimination phase), 14.9 min. The mean volume of distribution at steady state in the leg was 25.6 1. In the arterial part of the perfusion, the mean AUC was 155.9 mg min l-1, and that in the corresponding venous part was 91.6 mg min l-1. Leakage of the drug from the leg into the systemic circulation amounted to 1.2% of the total delivered dose; 91% of the delivered dose remained in the leg after the perfusion had been completed. The mean elimination half-life of mitoxantrone in the systemic circulation was 123 min and the corresponding AUC for systemic concentrations was 8.59 mg min l-1. The present data revealed a high uptake of mitoxantrone into the leg and low systemic drug concentrations due to minor leakage, suggesting that mitoxantrone might be a good candidate for use in isolated, hyperthermic limb perfusion.