Pharmacokinetics, drug metabolism, and tissue distribution of CPX-351 in animals.

CPX-351, a liposomal encapsulation of cytarabine and daunorubicin at a synergistic 5:1 molar ratio, is indicated for adults with newly diagnosed, therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. In preclinical species, this article demonstrated (1) similar release of cytarabine and daunorubicin by CPX-351 in plasma; (2) similar patterns of metabolism of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal cytarabine/daunorubicin combination; (3) prolonged tissue exposure to CPX-351; (4) dramatically different tissue distribution of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination (tissue:plasma ratios generally <1 versus >1, respectively); and (5) dramatically lower unbound plasma and tissue concentrations of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination. Together, these results provide insight into the safety profile of CPX-351, as well as mechanisms that drive the improved efficacy observed for CPX-351 versus the conventional 7 + 3 cytarabine/daunorubicin regimen in clinical studies.

Daunorubicin-containing CLL1-targeting nanomicelles have anti-leukemia stem cell activity in acute myeloid leukemia.

Patients with acute myeloid leukemia have a very poor prognosis related to a high rate of relapse and drug-related toxicity. The ability of leukemia stem cells (LSCs) to survive chemotherapy is primarily responsible for relapse, and eliminating LSCs is ultimately essential for cure. We developed novel disulfide-crosslinked CLL1-targeting micelles (DC-CTM), which can deliver high concentrations of daunorubicin (DNR) into both bulk leukemia cells and LSCs. Compared to free DNR, DC-CTM-DNR had a longer half-life, increased DNR area under the curve concentration by 11-fold, and exhibited a superior toxicity profile. In patient-derived AML xenograft models, DC-CTM-DNR treatment led to significant decreases in AML engraftment and impairment of secondary transplantation compared to control groups. Collectively, we demonstrate superior anti-LSC/AML efficacy, and preferable pharmacokinetic and toxicity profiles of DC-CTM-DNR compared to free DNR. DC-CTM-DNR has the potential to significantly improve treatment outcomes and reduce therapy-related morbidity and mortality for patients with AML.

Clofarabine, high-dose cytarabine and liposomal daunorubicin in pediatric relapsed/refractory acute myeloid leukemia: a phase IB study.

Survival in children with relapsed/refractory acute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m2/day × 5 days) and liposomal daunorubicin (40-80 mg/m2/day) were administered with cytarabine (2 g/m2/day × 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1st (n=11), early 1st (n=15), ≥2nd relapse (n=8). Dose level 3 (30 mg/m2clofarabine; 60 mg/m2liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m2 clofarabine with 60 mg/m2 liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine exposure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub) clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880.

Extravasation accidents with liposomal/liposomal pegylated anthracyclines treated with dexrazoxane: an overview and outcomes.

The extravasation of chemotherapeutic agents is a challenge for oncologic care teams. The management of nonliposomal (conventional) anthracyclines is well established in clinical practice guidelines, including general measures and specific antidotes, such as dexrazoxane. However, there is little scientific evidence on the management of liposomal and pegylated liposomal anthracyclines. The aim of this paper was to review the scientific literature on the extravasation of liposomal and pegylated liposomal anthracyclines and determine the clinical impact of this type of extravasation, focusing on dexrazoxane. The literature was searched using two databases: PubMed and Embase. Three searches were conducted, using liposomal anthracycline extravasation, pegylated liposomal anthracycline extravasation, and liposomal doxorubicin extravasation as keywords, respectively. Seven articles fulfilled the study eligibility criteria and included seventeen cases in humans. Extravasation occurred with three drugs: liposomal doxorubicin in nine (53%) patients, liposomal daunorubicin in four (23.5%) patients, and pegylated liposomal doxorubicin in four (23.5%) patients. General measures for extravasations were applied in all patients, but only three patients received dexrazoxane. All cases were completely resolved at 2-3 months, except for one patient, in whom dexrazoxane was not used. In animals, dexrazoxane decreased both the frequency of wounds produced by pegylated liposomal doxorubicin and their extent. The pharmacokinetic profiles of liposomal and pegylated liposomal anthracyclines differ from those of conventional anthracyclines, modifying their effectiveness and safety. General measures may be inadequate to heal areas affected by extravasation, which may require the administration of dexrazoxane. However, each case should be evaluated individually for the administration of dexrazoxane in off-label use until scientific evidence is available on its effectiveness and safety as an antidote for these formulations of anthracyclines.

Aldo-keto reductase 1C3 (AKR1C3): a missing piece of the puzzle in the dinaciclib interaction profile.

Dinaciclib is a multi-specific cyclin-dependent kinase (CDK) inhibitor with significant preclinical and clinical activity. It inhibits CDK1, CDK2, CDK5, CDK9 and CDK12 in the nanomolar range and exhibits potent antiproliferative effects on various cancers in vitro and in vivo. Aldo-keto reductases (AKR) and carbonyl reductases (CBR) are enzymes involved at the biosynthesis, intermediary metabolism and detoxification processes, but can also play a significant role in cancer resistance. Here, we report that dinaciclib is a strong inhibitor of aldo-keto reductase 1C3 (AKR1C3), an enzyme that is known to be an important regulator of cell proliferation and differentiation. AKR1C3 is overexpressed in a range of cancer types and is also involved in tumour cell resistance to anthracyclines. In our study, dinaciclib displayed tight-binding inhibition of human recombinant AKR1C3 (Kiapp = 0.07 µM) and was also active at the cellular level (IC50 = 0.23 µM). Dinaciclib acts as a noncompetitive inhibitor with respect to daunorubicin and as an uncompetitive inhibitor with respect to the NADPH. In subsequent experiments, pretreatment with dinaciclib (0.1 µM) significantly sensitized AKR1C3-overexpressing anthracycline-resistant cancer cells to daunorubicin. In conclusion, our results indicate that dinaciclib may potentially increase the therapeutic efficacy and safety of anthracyclines by preventing anthracycline resistance and minimizing their adverse effects.

Experience with generic pegylated L-asparaginase in children with acute lymphoblastic leukemia and monitoring of serum asparaginase activity.

BACKGROUND: Pegylated asparaginase (P-Asp) though integral to acute lymphoblastic leukemia (ALL) therapy is often not accessible to patients in developing countries. We share our clinical experience with generic P-Asp along with monitoring of asparaginase activity. METHODS: In this prospective observational study, patients ≤18 years of age with ALL were assigned to receive either generic P-Asp or native asparaginase (N-Asp) in a non-randomized manner. Treatment protocol was based on ALL BFM-95 backbone. The dose of P-Asp was 1500 IU/m2 by intravenous route during induction (Ia) and re-induction (IIa) phase of therapy. RESULTS: N-Asp or P-Asp was administered to 52 and 54 of the 106 eligible patients respectively. Demographic and disease characteristics were comparable in both arms. The mean trough levels for N-Asp and P-Asp were 156.87 ± 22.35 IU/L and 216.03 ± 73.40 IU/L, respectively (p value <0.001) and all patients achieved therapeutic levels during Ia. Incidence of asparaginase-attributable toxicity was similar in the two arms in both phases of treatment, although hospitalization due to noninfectious causes was more common in P-Asp arm during Ia (13% versus 0%, p value, 0.01). Clinical hypersensitivity and silent inactivation were not observed during Ia while these occurred in 13% and 5% of patients in the N-Asp arm and P-Asp arms of IIa, respectively. The 2-year event free survival for P-Asp and N-Asp groups was 84% and 80.7%, respectively (p value 0.85). CONCLUSION: Generic P-Asp was observed to be efficacious and well tolerated in our patients and adequate therapeutic levels were sustained for 2 weeks.

The daunorubicin interplay with mimetic model membranes of cancer cells: A biophysical interpretation.

The present work aimed to study the interactions between the anticancer drug daunorubicin and lipid membrane mimetic models of cancer cells composed by their most representative classes of phospholipids, with different degrees of complexity. Regarding these anticancer drug-membrane interactions, several biophysical parameters were assessed using liposomes (LUVs) composed of different molar ratios of DMPC, DOPC, DPPS, DOPE and Chol. In this context, daunorubicin's membrane concentration was determined by calculating its partition coefficient (Kp) between liposomes and water using derivative UV/vis spectrophotometry at 37°C and pH6.3, a typical tumoral microenvironment. Characterization of the zeta potential of such model membranes, in both the absence and presence of the compound, was accomplished through Electrophoretic Light Scattering (ELS). Fluorescence quenching studies, which determine the location of the drug within the bilayer, were carried out using liposomes labelled with DPH and TMA-DPH, fluorescent probes with known membrane position. Temperature dependent steady-state anisotropy assays were also performed to measure the daunorubicin effect on the membranes' microviscosity. The overall results support that daunorubicin permeation depends on the phospholipid membrane composition and causes alterations in the biophysical properties of the bilayers, namely in the membrane fluidity. The interaction of daunorubicin with the studied phospholipids is mainly driven by electrostatic and hydrophobic interactions. These insights demonstrated that not only membranes can affect daunorubicin accumulation in cells but the compound can alter the properties of membranes. The changes produced by daunorubicin on the lipid structure may constitute an additional mechanism of action, which might lead to modifications in the location and, consequently, the activity of membrane signaling proteins.

Synthesis and Characterization of Micelle-Forming PEG-Poly(Amino Acid) Copolymers with Iron-Hydroxamate Cross-Linkable Blocks for Encapsulation and Release of Hydrophobic Drugs.

Described is the development of a polymeric micelle drug delivery platform that addresses the physical property limitations of many nanovectors. The system employs triblock copolymers comprised of a hydrophilic poly(ethylene glycol) (PEG) block, and two poly(amino acid) (PAA) blocks: a stabilizing cross-linking central block, and a hydrophobic drug encapsulation block. Detailed description of synthetic strategies and considerations found to be critical are discussed. Of note, it was determined that the purity of the α-amino acid-N-carboxyanhydrides (NCA) monomers and PEG macroinitiator are ultimately responsible for impurities that arise during the polymerization. Also, contrary to current beliefs in the field, the presence of water does not adversely affect the polymerization of NCAs. Furthermore, we describe the impact of poly(amino acid) conformational changes, through the incorporation of d-amino acids to form mixed stereochemistry PAA blocks, with regard to the physical and pharmacokinetic properties of the resulting micelles.

Randomized trial comparing liposomal daunorubicin with idarubicin as induction for pediatric acute myeloid leukemia: results from Study AML-BFM 2004.

Outcomes of patients with acute myeloid leukemia (AML) improve significantly by intensification of induction. To further intensify anthracycline dosage without increasing cardiotoxicity, we compared potentially less cardiotoxic liposomal daunorubicin (L-DNR) to idarubicin at a higher-than-equivalent dose (80 vs 12 mg/m(2) per day for 3 days) during induction. In the multicenter therapy-optimization trial AML-BFM 2004, 521 of 611 pediatric patients (85%) were randomly assigned to L-DNR or idarubicin induction. Five-year results in both treatment arms were similar (overall survival 76% ± 3% [L-DNR] vs 75% ± 3% [idarubicin], Plogrank = .65; event-free survival [EFS] 59% ± 3% vs 53% ± 3%, Plogrank = .25; cumulative incidence of relapse 29% ± 3% vs 31% ± 3%, P(Gray) = .75), as were EFS results for standard (72% ± 5% vs 68% ± 5%, Plogrank = .47) and high-risk (51% ± 4% vs 46% ± 4%, Plogrank = .45) patients. L-DNR resulted in significantly better probability of EFS in patients with t(8;21). Overall, treatment-related mortality was lower with L-DNR than idarubicin (2/257 vs 10/264 patients, P = .04). Grade 3/4 cardiotoxicity was rare after induction (4 L-DNR vs 5 idarubicin). Only 1 L-DNR and 3 idarubicin patients presented with subclinical or mild cardiomyopathy during follow-up. In conclusion, at the given dose, L-DNR has overall antileukemic activity comparable to idarubicin, promises to be more active in subgroups, and causes less treatment-related mortality. This trial was registered at www.clinicaltrials.gov as #NCT00111345.

[The study of mechanisms of accumulation of daunorubicin and rodamin-123 in cells of human venous blood using cytometry technique].

The article presents comparative data of cytometry estimation of accumulation of daunorubicin and rodamin-123 in cells of peripheralbloodofhealthypeople underincubation ofsubstances in vitro. It is demonstrated that maximal saturation of thrombocytes occurs during the first five minutes, of leukocytes during forty five minutes. The erythrocytes factually never accumulate these compounds. The maximal values of accumulation of substances in leukocytes are characterized by high inter-individual variation. The close correlation (Rs = 0.96-0.98) of parameters of accumulation of substances in lymphocytes and neutrophils testifies the presence ofsimilar mechanisms ofcontrol ofactivity transportation ofxenobiotics in nucleated cells of blood. However, the results of inhibitor analysis of input of Pgp-dependent mechanisms of accumulation of rodamin-123 by leukocytes differ the data received under application of daunorubicin that reflects differences of their intracellular binding sites. The expressed differences between parameters of accumulation ofdaunorubicin and rodamin-123 by leukocytes in various patients determine necessity of individual approach in monitoring of development of medicinal resistance.

A phase 1/2 study of NS-87/CPX-351 (cytarabine and daunorubicin liposome) in Japanese patients with high-risk acute myeloid leukemia.

OBJECTIVES: NS-87/CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin. NS-87/CPX-351 exerts antileukemic action by maintaining a synergistic molar ratio of cytarabine to daunorubicin of 5:1 within the liposome while in circulation. Patients with high-risk acute myeloid leukemia (AML), which includes therapy-related AML and AML with myelodysplasia-related changes (AML-MRC), have poorer outcomes than those with other AML. METHODOLOGY: This open-label phase 1/2 (P1/2) study was conducted in 47 Japanese patients aged 60-75 years with newly diagnosed high-risk AML to evaluate the pharmacokinetics, safety, and efficacy of NS-87/CPX-351. RESULTS: In the 6 patients enrolled in the P1 portion, no dose-limiting toxicities (DLTs) were reported, and 100 units/m2 during the induction cycle was found to be acceptable. Cytarabine and daunorubicin had a long half-life in the terminal phase (32.8 and 28.7 h, respectively). In the 35 patients enrolled in the P2 portion, composite complete remission (CRc; defined as complete remission [CR] or CR with incomplete hematologic recovery [CRi]) was achieved in 60.0% (90% CI: 44.7-74.0) of the patients. Adverse events due to NS-87/CPX-351 were well tolerated. OUTCOMES: NS-87/CPX-351 can be considered as a frontline treatment option for Japanese patients with high-risk AML.

Carbonyl reductase 1 expression influences daunorubicin metabolism in acute myeloid leukemia.

PURPOSE: The present study aimed to investigate the role of expression of daunorubicin-metabolizing enzymes carbonyl reductase 1 and 3 (CBR1 and CBR3) on the in vitro cytotoxicity of daunorubicin in primary acute myeloid leukemia (AML) cells and the effect of genetic variants in CBR1 and CBR3 on the plasma pharmacokinetics of daunorubicin and daunorubicinol (DOL) in AML patients. METHODS: RNA expression of CBR1 and CBR3, intracellular daunorubicin and DOL levels, and in vitro cytotoxicity of daunorubicin were measured in bone marrow mononuclear cells of 104 adult AML patients. Plasma pharmacokinetics of daunorubicin and DOL was measured in 24 patients receiving daunorubicin-based induction chemotherapy for AML. RESULTS: Increased expression of CBR1 significantly reduced the in vitro cytotoxicity of daunorubicin and also positively correlated with intracellular DOL levels. Polymorphisms in CBR1 and CBR3 did not show any association with intracellular daunorubicin or DOL levels, but there was a trend towards significant increase in plasma daunorubicin systemic exposure in patients with a variant genotype for CBR1 polymorphism rs25678. CONCLUSIONS: This pilot study suggests that CBR1 RNA expression may be helpful in identifying AML patients at risk of developing resistance or toxicity to daunorubicin due to increased formation of DOL. Further confirmation of these findings in a larger sample pool would be required to determine the applicability of these results. Inhibition of CBR1 can be an option to improve the efficacy and prevent toxicity related to the treatment. Influence of daunorubicin and DOL plasma levels on clinical outcome, if any, remains to be evaluated.

The liposomal daunorubicin plus tamoxifen: improving the stability, uptake, and biodistribution of carriers.

The synergistic effects of tamoxifen on the sensitivity of MCF-7 cells to daunorubicin have been reported. Whether the effects of daunorubicin on MCF-7/adr cells can be improved by tamoxifen in liposomes and how tamoxifen changes daunorubicin's behavior in vivo remains unclear. The aim of this study was to investigate the effects of tamoxifen on the uptake and biodistribution of daunorubicin liposomes by breast-cancer-resistant MCF-7/adr cells in vitro and in vivo. The uptake of liposomes by MCF-7/adr cells in vitro studies was measured using flow cytometry and laser confocal microscopy. The biodistributions of carriers and free drugs were evaluated by DiR dye using in vivo imaging. Tamoxifen obviously enhanced the cellular uptake of liposomes by MCF-7/adr cells in time-dependent manners. According to the results from in vivo imaging analysis, the mean fluorescence intensity of DiR liposomes with tamoxifen in the tumor regions of MCF-7/adr tumor-bearing nude mice was much stronger than that of DiR liposomes alone (16,450 ± 1,331 versus 3,666 ± 321; n = 3). Pegylated liposomes elongated the existence of daunorubicin in the circulatory system and the enhanced permeability and retention effect enhanced its concentration in local tumor tissues, which may provide the precondition for tamoxifen further promoting the uptake by MCF-7/Adr cells in vivo. Using daunorubicin liposomes and tamoxifen together generates better biodistribution profiles in tumor tissue than using daunorubicin liposomes only, which contributes to improving the therapeutic effect of breast cancer treatment.

[High-density lipoproteins as a form of daunorubicin transport in hepatoma cells of mice].

The efficiency of using high-density lipoproteins (HDLPs) as the transport form of an antineoplastic drug daunorubicin (rubomycin hydrochloride, daunoxome) has been shown on the culture of HA-1 hepatoma cells of mice. The use of HDLPs in a complex with daunorubicin led to an increase in the efficiency of drug transport and cytotoxic action with respect to tumor cells in comparison with hepatocytes of healthy animals.

A new daunomycin-peptide conjugate: synthesis, characterization and the effect on the protein expression profile of HL-60 cells in vitro.

Daunomycin (Dau) is a DNA-binding antineoplastic agent in the treatment of various types of cancer, such as osteosarcomas and acute myeloid leukemia. One approach to improve its selectivity and to decrease the side effects is the conjugation of Dau with oligopeptide carriers, which might alter the drug uptake and intracellular fate. Here, we report on the synthesis, characterization, and in vitro biological properties of a novel conjugate in which Dau is attached, via an oxime bond, to one of the cancer specific small peptides (LTVSPWY) selected from a random phage peptide library. The in vitro cytostatic effect and cellular uptake of Dau═Aoa-LTVSPWY-NH(2) conjugate were studied on various human cancer cell lines expressing different levels of ErbB2 receptor which could be targeted by the peptide. We found that the new daunomycin-peptide conjugate is highly cytostatic and could be taken up efficiently by the human cancer cells studied. However, the conjugate was less effective than the free drug itself. RP-HPLC data indicate that the conjugate is stable at least for 24 h in the pH 2.5-7.0 range of buffers, as well as in cell culture medium. The conjugate in the presence of rat liver lysosomal homogenate, as indicated by LC-MS analysis, could be degraded. The smallest, Dau-containing metabolite (Dau═Aoa-Leu-OH) identified and prepared expresses DNA-binding ability. In order to get insight on the potential mechanism of action, we compared the protein expression profile of HL-60 human leukemia cells after treatment with the free and peptide conjugated daunomycin. Proteomic analysis suggests that the expression of several proteins has been altered. This includes three proteins, whose expression was lower (tubulin ß chain) or markedly higher (proliferating cell nuclear antigen and protein kinase C inhibitor protein 1) after administration of cells with Dau-conjugate vs free drug.

In vitro degradation and antitumor activity of oxime bond-linked daunorubicin-GnRH-III bioconjugates and DNA-binding properties of daunorubicin-amino acid metabolites.

Bioconjugates with receptor-mediated tumor-targeting functions and carrying cytotoxic agents should enable the specific delivery of chemotherapeutics to malignant tissues, thus increasing their local efficacy while limiting the peripheral toxicity. In the present study, gonadotropin-releasing hormone III (GnRH-III; Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH(2)) was employed as a targeting moiety to which daunorubicin was attached via oxime bond, either directly or by insertion of a GFLG or YRRL tetrapeptide spacer. The in vitro antitumor activity of the bioconjugates was determined on MCF-7 human breast and HT-29 human colon cancer cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Their degradation/stability (1) in human serum, (2) in the presence of cathepsin B and (3) in rat liver lysosomal homogenate was analyzed by liquid chromatography in combination with mass spectrometry. The results show that (1) all synthesized bioconjugates have in vitro antitumor effect, (2) they are stable in human serum at least for 24 h, except for the compound containing an YRRL spacer and (3) they are hydrolyzed by cathepsin B and in the lysosomal homogenate. To investigate the relationship between the in vitro antitumor activity and the structure of the bioconjugates, the smallest metabolites produced in the lysosomal homogenate were synthesized and their binding to DNA was assessed by fluorescence spectroscopy. Our data indicate that the incorporation of a peptide spacer in the structure of oxime bond-linked daunorubicin-GnRH-III bioconjugates is not required for their antitumor activity. Moreover, the antitumor activity is influenced by the structure of the metabolites (daunorubicin-amino acid derivatives) and their DNA-binding properties.

Inverse relationship between leukaemic cell burden and plasma concentrations of daunorubicin in patients with acute myeloid leukaemia.

AIMS: It has been shown that the cellular uptake and cytotoxicity of anthracyclines decrease with increasing cell density in vitro, an event termed 'the inocculum effect'. It is not known whether such an effect occurs in vivo. In this study the relationships between white blood cell (WBC) count, plasma and cellular concentrations of daunorubicin (DNR) in patients with acute myeloid leukaemia were investigated. METHODS: Plasma and mononuclear blood cells were isolated from peripheral blood from 40 patients with acute myeloid leukaemia at end of infusion (time 1 h), 5 and 24 h following the first DNR infusion. DNR concentrations were determined by high-pressure liquid chromatography and related to the WBC count at diagnosis. A population pharmacokinetic model was used to estimate the correlations between baseline WBC count, volume of distribution and clearance of DNR. RESULTS: A clear but weak inverse relationship between the baseline WBC count and plasma concentrations of DNR (r(2)=0.11, P<0.05) at time 1 was found. Furthermore, a clear relationship between baseline WBC count and DNR central volume of distribution using population pharmacokinetic modelling (dOFV 4.77, P<0.05) was also noted. Analysis of plasma DNR and the metabolite daunorubicinol (DOL) concentrations in patients with a high WBC count support that the low DNR/DOL concentrations are due a distribution effect. CONCLUSION: This study shows that the leukaemic cell burden influences the plasma concentrations of anthracyclines. Further studies are needed to explore if patients with high a WBC count may require higher doses of anthracyclines.

Pharmacokinetics and tissue distribution of dual-targeting daunorubicin liposomes in mice.

BACKGROUND: To circumvent the problem of transporting anticancer drugs across the blood-brain barrier (BBB) to target brain tumors, we have previously developed dual-targeting daunorubicin liposomes modified with 4-aminophenyl-α-D-manno-pyranoside and transferrin molecules. The objective of the present study was to evaluate the pharmacokinetics and distribution of daunorubicin after intravenous administration of dual-targeting daunorubicin liposomes. METHODS: We evaluated pharmacological parameters in normal KunMing mice. Drug concentrations in plasma, heart, spleen, lung, kidney and brain were measured using HPLC-UV. RESULTS: The plasma drug concentration-time profile of the daunorubicin dual-targeting liposomes decreased more slowly than free daunorubicin in the initial phase and maintained higher drug levels in the terminal phase, resulting in longer blood exposure to daunorubicin liposomes compared with the free drug. Daunorubicin levels were lower in heart tissue and significantly higher in brain tissue after administration of the dual-targeting liposomes compared with the free drug. Daunorubicin was detected at varying levels in the liver, spleen, lung and kidney tissues. CONCLUSION: Our results indicate that dual-targeting daunorubicin liposomes improve the daunorubicin blood circulation time and show an enhanced drug transport potential across the BBB.

Micellar electrokinetic chromatographic analysis for in vitro accumulation of anthracyclines enhanced by inhibitors of cell membrane transporter-proteins in cancer cells.

Cell membrane transporter-proteins have been partly implicated in lowering the accumulation of drugs in cancer cells, leading to multidrug resistance (MDR). Two cancer cell lines, A549 and RDES, were continuously exposed to subclinical concentration (250 nM) of anthracyclines and micellar electrokinetic chromatography was used to investigate their in vitro accumulation after treatment with inhibitors of membrane transporter-proteins. The four anthracylines [doxorubicin (DOX), epirubicin (EPI), daunorubicin (DNR), and idarubicin (IDA)] were separated within a short analysis time of less than 15 min in borate buffer (80 mM, pH 9.22) containing sodium taurodeoxycholate (35 mM), 2-hydroxypropyl-γ-cyclodextrin (3.5% wt/v), and sodium dodecylsulfate (20 mM). Laser-induced fluorescence was used for detection of the anthracyclines. Three inhibitors, verapamil, cyclosporine A and probenecid, were examined by adding each inhibitor independently or two inhibitors simultaneously to the culture medium. It was found that independent use of each inhibitor leads to more efficient accumulation than combined use of verapamil and probenecid. In addition, the results show that effect of inhibitors on the accumulation of anthracyclines depended on type of cell: in RDES, inhibitors enhanced accumulation of all four anthracyclines, while in A549, inhibitors showed different accumulation behavior for each anthracycline. Generally higher accumulation of anthracyclines was observed in RDES cells than A549, as evidenced by dead cells (7-16%) after 24 h of continuous exposure to subclinical concentration.

Different transport activity of human triallelic MDR1 893Ala/Ser/Thr variant and its association with herb extracts.

Individual pharmacokinetic differences for herb-drug interaction have been associated with genetic variations of the multidrug resistance (MDR) gene. A high level expression of MDR protein increases cellular efflux and might decrease drug sensitivity. This study investigated the drug efflux activity difference of human MDR1 triallelic variant 2677G/T/A (rs2032582), as a nonsynonymous 893Ala/Ser/Thr, using Xenopus laevis oocytes and MDR1 overexpressing LLC-PK1 cells. Two MDR1 variants (2667T/893Ser and 2667A/893Thr) were generated using human MDR1 cDNA (2677G/893Ala). No significant difference in the expression of MDR1 893Ala/Ser/Thr was found in X. laevis oocytes. However, the MDR1 2667A/893Thr variant interestingly showed a significant decrease of efflux activity for both digoxin and daunorubicin compared with those of 893Ala and 893Ser variants. In further investigation assessing the inhibitory effects of three herbal extracts on MDR1, 893Ala and 893Ser showed significant decreases of efflux activities in treatments with P. cocos (p = 0.005 for 893Ser) and D. dasycarpus (p = 0.0009 for 893Ala; p = 0.002 for 893Ser) in X. laevis oocytes. The results in this study suggest that herbal medicines could interact with other drugs and change the therapeutic effects depending on the genetic polymorphisms of individuals.