DNA-Binding Anticancer Drugs: One Target, Two Actions.

Amsacrine, an anticancer drug first synthesised in 1970 by Professor Cain and colleagues, showed excellent preclinical activity and underwent clinical trial in 1978 under the auspices of the US National Cancer Institute, showing activity against acute lymphoblastic leukaemia. In 1984, the enzyme DNA topoisomerase II was identified as a molecular target for amsacrine, acting to poison this enzyme and to induce DNA double-strand breaks. One of the main challenges in the 1980s was to determine whether amsacrine analogues could be developed with activity against solid tumours. A multidisciplinary team was assembled in Auckland, and Professor Denny played a leading role in this approach. Among a large number of drugs developed in the programme, N-[2-(dimethylamino)-ethyl]-acridine-4-carboxamide (DACA), first synthesised by Professor Denny, showed excellent activity against a mouse lung adenocarcinoma. It underwent clinical trial, but dose escalation was prevented by ion channel toxicity. Subsequent work led to the DACA derivative SN 28049, which had increased potency and reduced ion channel toxicity. Mode of action studies suggested that both amsacrine and DACA target the enzyme DNA topoisomerase II but with a different balance of cellular consequences. As primarily a topoisomerase II poison, amsacrine acts to turn the enzyme into a DNA-damaging agent. As primarily topoisomerase II catalytic inhibitors, DACA and SN 28049 act to inhibit the segregation of daughter chromatids during anaphase. The balance between these two actions, one cell cycle phase specific and the other nonspecific, together with pharmacokinetic, cytokinetic and immunogenic considerations, provides links between the actions of acridine derivatives and anthracyclines such as doxorubicin. They also provide insights into the action of cytotoxic DNA-binding drugs.

In-silico Design, ADMET Screening, MM-GBSA Binding Free Energy of Some Novel Isoxazole Substituted 9-Anilinoacridines as HER2 Inhibitors Targeting Breast Cancer.

BACKGROUND: Human Epidermal development factor Receptor-2 (HER2) is a membrane tyrosine kinase which is overexpressed and gene amplified in human breast cancers. HER2 amplification and overexpression have been linked to important tumor cell proliferation and survival pathways for 20% of instances of breast cancer. 9-aminoacridines are significant DNA-intercalating agents because of their antiproliferative properties. OBJECTIVE: Some novel isoxazole substituted 9-anilinoacridines(1a-z) were designed by in-silico technique for their HER2 inhibitory activity. Docking investigations of compounds 1a-z are performed against HER2 (PDB id-3PP0) by using Schrodinger suit 2016-2. METHODS: Molecular docking study for the designed molecules 1a-z are performed by Glide module, in-silico ADMET screening by QikProp module and binding free energy by Prime-MMGBSA module of Schrodinger suit. The binding affinity of designed molecules 1a-z towards HER2 was chosen based on GLIDE score. RESULTS: Many compounds showed good hydrophobic communications and hydrogen bonding associations to hinder HER2. The compounds 1a-z, aside from 1z have significant Glide scores in the scope of - 4.91 to - 10.59 when compared with the standard Ethacridine (- 4.23) and Tamoxifen (- 3.78). The in-silico ADMET properties are inside the suggested about drug likeness. MM-GBSA binding of the most intense inhibitor is positive. CONCLUSION: The outcomes reveal that this study provides evidence for the consideration of isoxazole substituted 9-aminoacridine derivatives as potential HER2 inhibitors. The compounds, 1s,x,v,a,j,r with significant Glide scores may produce significant anti breast cancer activity and further in vitro and in vivo investigations may prove their therapeutic potential.

Multiseed liposomal drug delivery system using micelle gradient as driving force to improve amphiphilic drug retention and its anti-tumor efficacy.

To improve drug retention in carriers for amphiphilic asulacrine (ASL), a novel active loading method using micelle gradient was developed to fabricate the ASL-loaded multiseed liposomes (ASL-ML). The empty ML were prepared by hydrating a thin film with empty micelles. Then the micelles in liposomal compartment acting as 'micelle pool' drove the drug to be loaded after the outer micelles were removed. Some reasoning studies including critical micelle concentration (CMC) determination, influencing factors tests on entrapment efficiency (EE), structure visualization, and drug release were carried out to explore the mechanism of active loading, ASL location, and the structure of ASL-ML. Comparisons were made between pre-loading and active loading method. Finally, the extended drug retention capacity of ML was evaluated through pharmacokinetic, drug tissue irritancy, and in vivo anti-tumor activity studies. Comprehensive results from fluorescent and transmission electron microscope (TEM) observation, encapsulation efficiency (EE) comparison, and release studies demonstrated the formation of ML-shell structure for ASL-ML without inter-carrier fusion. The location of drug mainly in inner micelles as well as the superiority of post-loading to the pre-loading method , in which drug in micelles shifted onto the bilayer membrane was an additional positive of this delivery system. It was observed that the drug amphiphilicity and interaction of micelles with drug were the two prerequisites for this active loading method. The extended retention capacity of ML has been verified through the prolonged half-life, reduced paw-lick responses in rats, and enhanced tumor inhibition in model mice. In conclusion, ASL-ML prepared by active loading method can effectively load drug into micelles with expected structure and improve drug retention.

Optimization of Weight Ratio for DSPE-PEG/TPGS Hybrid Micelles to Improve Drug Retention and Tumor Penetration.

PURPOSE: To enhance therapeutic efficacy and prevent phlebitis caused by Asulacrine (ASL) precipitation post intravenous injection, ASL-loaded hybrid micelles with size below 40 nm were developed to improve drug retention and tumor penetration. METHODS: ASL-micelles were prepared using different weight ratios of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethyleneglycol-2000 (DSPE-PEG2000) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) polymers. Stability of micelles was optimized in terms of critical micelle concentration (CMC) and drug release properties. The encapsulation efficiency (EE) and drug loading were determined using an established dialysis-mathematic fitting method. Multicellular spheroids (MCTS) penetration and cytotoxicity were investigated on MCF-7 cell line. Pharmacokinetics of ASL-micelles was evaluated in rats with ASL-solution as control. RESULTS: The ASL-micelles prepared with DSPE-PEG2000 and TPGS (1:1, w/w) exhibited small size (~18.5 nm), higher EE (~94.12%), better sustained in vitro drug release with lower CMC which may be ascribed to the interaction between drug and carriers. Compared to free ASL, ASL-micelles showed better MCTS penetration capacity and more potent cytotoxicity. Pharmacokinetic studies demonstrated that the half-life and AUC values of ASL-micelles were approximately 1.37-fold and 3.49-fold greater than that of free ASL. CONCLUSIONS: The optimized DSPE-PEG2000/TPGS micelles could serve as a promising vehicle to improve drug retention and penetration in tumor.

Quantitative determination of intracellular Asulacrine in MCF-7 breast cancer cells by liquid chromatography-mass spectrometry and its application to cellular pharmacokinetic studies of P188 modified liposomes.

Asulacrine (ASL), an analogue of amsacrine, has shown higher anti-breast and anti-lung cancer activity. Hereby, a new sensitive and selective liquid chromatography-mass spectrometry (LC/MS) method was developed to determine intracellular asulacrine. The chromatographic separation was performed on an Agilent Zorbax Extend-C18 column (2.1 mm i.d. × 50 mm, 5 µm) using gradient elution with water (2 mmol/L ammonium acetate and 0.1% acetic acid) and acetonitrile as the mobile phase. The detection was achieved with selected ion monitoring mode using electrospray ionization in positive mode with target ions at m/z 465.3 and m/z 326.1 for asulacrine and midazolam, respectively. The standard curve showed a good linearity with the lower limit of quantification of 1 ng/mL, as a result of which, the trace concentration of ASL in cell suspension could be quantified. The intra- and inter-day accuracy ranged from -5.28 to 6.5% and from -6.32 to 1.05%, and the intra- and inter-day precisions were no more than 7.65% and 11.71%, respectively. Additionally, no degradation of asulacrine was observed during stability evaluation. The method was proved to be powerful and practical to determine and compare the intracellular distribution and kinetics of ASL under different formulations in MCF-7 breast cancer cells.

Amsacrine analog-loaded solid lipid nanoparticle to resolve insolubility for injection delivery: characterization and pharmacokinetics.

Amsacrine analog is a novel chemotherapeutic agent that provides potentially broad antitumor activity when compared to traditional amsacrine. However, the major limitation of amsacrine analog is that it is highly lipophilic, making it nonconductive to intravenous administration. The aim of this study was to utilize solid lipid nanoparticles (SLN) to resolve the delivery problem and to investigate the biodistribution of amsacrine analog-loaded SLN. Physicochemical characterizations of SLN, including particle size, zeta potential, entrapment efficiency, and stability, were evaluated. In vitro release behavior was also measured by the dialysis method. In vivo pharmacokinetics and biodistribution behavior of amsacrine analog were investigated and incorporated with a non invasion in vivo imaging system to confirm the localization of SLN. The results showed that amsacrine analog-loaded SLN was 36.7 nm in particle size, 0.37 in polydispersity index, and 34.5±0.047 mV in zeta potential. More than 99% of amsacrine analog was successfully entrapped in the SLN. There were no significant differences in the physicochemical properties after storage at room temperature (25°C) for 1 month. Amsacrine analog-loaded SLN maintained good stability. An in vitro release study showed that amsacrine analog-loaded SLN sustained a release pattern and followed the zero equation. An in vivo pharmacokinetics study showed that amsacrine analog was rapidly distributed from the central compartment to the tissue compartments after intravenous delivery of amsacrine analog-loaded SLN. The biodistribution behavior demonstrated that amsacrine analog mainly accumulated in the lungs. Noninvasion in vivo imaging system images also confirmed that the drug distribution was predominantly localized in the lungs when IR-780-loaded SLN was used.

Post-insertion of poloxamer 188 strengthened liposomal membrane and reduced drug irritancy and in vivo precipitation, superior to PEGylation.

The ultimate aim of this study was to develop asulacrine (ASL)-loaded long-circulating liposomes to prevent phlebitis during intravenous (i.v.) infusion for chemotherapy. Poly(ethylene)glycol (PEG) and poloxamer 188-modified liposomes (ASL-PEGL and ASL-P188L) were developed, and ASL was loaded using a remote loading method facilitated with a low concentration of sulfobutyl ether-ß-cyclodextrin as a drug solubilizer. The liposomes were characterized in terms of morphology, size, release properties and stability. Pharmacokinetics and venous tissue tolerance of the formulations were simultaneously studied in rabbits following one-hour i.v. infusion via the ear vein. The irritancy was assessed using a rat paw-lift/lick model after subplantar injections. High drug loading 9.0% w/w was achieved with no drug leakage found from ASL-PEGL or ASL-P188L suspended in a 5% glucose solution at 30days. However, a rapid release (leakage) from ASL-PEGL was observed when PBS was used as release medium, partially related to the use of cyclodextrin in drug loading. Post-insertion of poloxamer 188 to the liposomes appeared to be able to restore the drug retention possibly by increasing the packing density of phospholipids in the membrane. In rabbits (n=5), ASL-P188L had a prolonged half-life with no drug precipitation or inflammation in the rabbit ear vein in contrast to ASL solution. Following subplantar (footpad) injections in rats ASL solution induced paw-lick/lift responses in all rats whereas ASL-P188L caused no response (n=8). PEGylation showed less benefit possibly due to the drug 'leakage'. In conclusion, drug precipitation in the vein and the drug mild irritancy may both contribute to the occurrence of phlebitis caused by the ASL solution, and could both be prevented by encapsulation of the drug in liposomes. Poloxamer 188 appeared to be able to 'seal' the liposomal membrane and enhance drug retention. The study also highlighted the importance of bio-relevant in vitro release study in formulation screening.

Strategies to maximize liposomal drug loading for a poorly water-soluble anticancer drug.

PURPOSE: To develop a liposomal system with high drug loading (DL) for intravenous (i.v.) delivery of a poorly water-soluble basic drug, asulacrine (ASL). METHODS: A thin-film hydration and extrusion method was used to fabricate the PEGylated liposomal membranes followed by a freeze and thaw process. A novel active drug loading method was developed using ammonium sulphate gradient as an influx driving force of ASL solubilized with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD). DL was maximized by optimizing liposomal preparation and loading conditions. Pharmacokinetics was evaluated following i.v. infusion in rabbits. RESULTS: Freeze-thaw resulted in unilamellar liposome formation (180 nm) free of micelles. Higher DL was obtained when dialysis was used to remove the untrapped ammonium sulphate compared to ultracentrifuge. The pH and SBE-ß-CD level in the loading solution played key roles in enhancing DL. High DL ASL-liposomes (8.9%w/w, drug-to-lipid mole ratio 26%) were obtained with some drug "bundles" in the liposomal cores and were stable in a 5% glucose solution for >80 days with minimal leakage (<2%). Surprisingly, following administration of ASL-liposomes prepared with or without SBE-ß-CD, the half-lives were similar to the drug solution despite an increased area under the curve, indicating drug leakage from the carriers. CONCLUSIONS: High liposomal DL was achieved with multiple strategies for a poorly-water soluble weak base. However, the liposomal permeability needed to be tailored to improve drug retention.

Modification of polyethylene glycol onto solid lipid nanoparticles encapsulating a novel chemotherapeutic agent (PK-L4) to enhance solubility for injection delivery.

BACKGROUND: The synthetic potential chemotherapeutic agent 3-Chloro-4-[(4-methoxyphenyl) amino]furo[2,3-b]quinoline (PK-L4) is an analog of amsacrine. The half-life of PK-L4 is longer than that of amsacrine; however, PK-L4 is difficult to dissolve in aqueous media, which is problematic for administration by intravenous injection. AIMS: To utilize solid lipid nanoparticles (SLNs) modified with polyethylene glycol (PEG) to improve the delivery of PK-L4 and investigate its biodistribution behavior after intravenous administration. RESULTS: The particle size of the PK-L4-loaded SLNs was 47.3 nm and the size of the PEGylated form was smaller, at 28 nm. The entrapment efficiency (EE%) of PK-L4 in SLNs with and without PEG showed a high capacity of approximately 100% encapsulation. Results also showed that the amount of PK-L4 released over a prolonged period from SLNs both with and without PEG was comparable to the non-formulated group, with 16.48% and 30.04%, respectively, of the drug being released, which fit a zero-order equation. The half-maximal inhibitory concentration values of PK-L4-loaded SLNs with and those without PEG were significantly reduced by 45%-64% in the human lung carcinoma cell line (A549), 99% in the human breast adenocarcinoma cell line with estrogen receptor (MCF7), and 95% in the human breast adenocarcinoma cell line (MDA-MB-231). The amount of PK-L4 released by SLNs with PEG was significantly higher than that from the PK-L4 solution (P < 0.05). After intravenous bolus of the PK-L4-loaded SLNs with PEG, there was a marked significant difference in half-life alpha (0.136 ± 0.046 hours) when compared with the PK-L4 solution (0.078 ± 0.023 hours); also the area under the curve from zero to infinity did not change in plasma when compared to the PK-L4 solution. This demonstrated that PK-L4-loaded SLNs were rapidly distributed from central areas to tissues and exhibited higher accumulation in specific organs. The highest deposition of PK-L4-loaded SLNs with PEG was found in the lung and spine. CONCLUSION: Sufficient amounts of PK-L4 were entrapped in the SLNs, and the pharmacokinetic behavior of PK-L4-loaded SLNs was established. This formulation successfully resolved the delivery problem, and the drug was localized in particular organs.

Formulation and pharmacokinetic evaluation of an asulacrine nanocrystalline suspension for intravenous delivery.

Asulacrine (ASL) is an inhibitor of topoisomerase II, which has shown potential against breast and lung cancer. It is a poorly water soluble drug. To allow intravenous (i.v.) administration, ASL was formulated as a nanocrystalline suspension by high pressure homogenization. The nanosuspension was lyophilized to obtain the dry ASL nanoparticles (average size, 133+/-20nm), which enhanced both the physical and chemical stability of the ASL nanoparticles. ASL dissolution and saturation solubility were enhanced by the nanosuspension. Differential scanning calorimetry and X-ray diffraction analysis showed that the crystallinity of the ASL was preserved during the high pressure homogenization process. The pharmacokinetics and tissue distribution of ASL administered either as a nanosuspension or as a solution were compared after i.v. administration to mice. In plasma, ASL nanosuspension exhibited a significantly (P<0.01) reduced C(max) (12.2+/-1.3microg ml(-1)vs 18.3+/-1.0microg ml(-1)) and AUC(0-infinity) (18.7+/-0.5microg ml(-1)h vs 46.4+/-2.6microg ml(-1)h), and a significantly (P<0.01) greater volume of distribution (15.5+/-0.6lkg(-1)vs 2.5+/-0.1lkg(-1)), clearance (1.6+/-0.04lh(-1)kg(-1)vs 0.6+/-0.04lh(-1)kg(-1)) and elimination half-life (6.1+/-0.1h vs 2.7+/-0.2h) compared to the ASL solution. In contrast, the ASL nanosuspension resulted in a significantly greater AUC(0-infinity) in liver, lung and kidney (all P<0.01), but not in heart.

Development and validation of bioanalytical method for the determination of asulacrine in plasma by liquid chromatography.

Asulacrine (9-[(2-methoxy-4-methylsulphonylamino)phenylamino]-N,5-dimethyl-4-acridinecarboxamide), an analogue of the antileukaemia drug amsacrine, has high antitumour activity in mice and has also shown clinical activity. A simple method is described for the quantitation of asulacrine in plasma by liquid chromatography. Chromatographic separation was achieved on a reversed phase C 18 column (250 mm x 4.6mm, particle size 5 microm, Gemini) using isocratic elution (acetonitrile and 0.01 M sodium acetate buffer pH 4.0, 45/55, v/v) at a flow rate of 1 ml/min. Asulacrine and internal standard (the ethylsulphonanilide analogue) were measured using UV detection at 254 nm. The total chromatographic run-time was 8 min with asulacrine and internal standard eluting at approximately 4.7 and approximately 6.5 min, respectively. Limit of quantification was 0.1microg/ml. The linearity range of the method was 0.1-10 microg/ml (r2=0.9995). Mean recoveries from plasma were 100-105%. Intra-batch and inter-batch precision was 7.1 and 7.8%, respectively, and intra-batch and inter-batch accuracy (relative error) was 4.9 and 8.4%, respectively (n=8 in all cases). The bench top, freeze thaw, short-term storage and stock solution stability evaluation indicated no evidence of degradation of asulacrine. The validated method is simple, selective and rapid and can be used for pharmacokinetic studies in mice.

Highly sensitive analysis of the anti-tumor agent 1-[4-(furo[2,3-b]-quinolin-4-ylamino)phenyl]ethanone in rat plasma by high-performance liquid chromatography using electrochemical detection.

A sensitive high-performance liquid chromatography method with electrochemical detection was developed for the purpose of determining the concentration of the new anti-tumor agent 1-[4-(furo[2,3-b]-quinolin-4-ylamino)phenyl]ethanone (FQPE) in rats. The plasma samples were spiked with the internal standard diclofenac and extracted using dichloromethane. A C(18) 250 mm x 4mm column was used for the separation of analyte with a mobile phase consisting of 50% acetonitrile and 50% pH 3.0 of sodium 1-pentansulfonate solution at a flow rate of 1.0 mL/min. FQPE was detected by electrochemical detector at 1.0 V and 20 nA. Intra-day and inter-day precision and accuracy were acceptable down to the limit of quantization of 1 ng/mL. The lower limit of detection (LOD) was 0.5 ng/mL. The pharmacokinetic parameters of FQPE in rats after intravenous administration of 2.1 and 4.2 mg/kg were determined. The apparent volume of distribution, half-life of elimination, and clearance showed no significant difference between the two dosages. The area under the plasma concentration time curve increased proportionally with dose. The half-life of FQPE was prolonged about 2.4-fold, compared with amsacrine.

A study of amsalog (CI-921) administered orally on a 5-day schedule, with bioavailability and pharmacokinetically guided dose escalation.

PURPOSE: Amsalog is a derivative of 9-aminoacridine. Phase I studies using intravenous (i.v.) amsalog have shown the dose-limiting toxicity (DLT) to be phlebitis and myelosuppression. Phase II studies using a variety of schedules have shown evidence of activity in patients with large-cell lung, breast, and head and neck cancers. Preclinical studies demonstrated that amsalog is active orally: a clinical study of the oral bioavailability of amsalog was therefore performed. METHODS: A group of 20 patients with refractory malignancies were treated. There were two phases of the study: a pharmacokinetic comparison of i.v. against oral amsalog, followed by a pharmacokinetically guided oral dose escalation study. In the first phase of the study, 11 patients were treated. Amsalog 50 mg/m2 was administered i.v., and 50 mg/m2 and 200 mg/m2 orally. In the second phase of the study, 9 patients were treated in three cohorts of three. On day 1 of a 5-day schedule, amsalog was administered i.v. at the maximum tolerated dose (MTD) of 200 mg/m2. Subsequent doses were given orally, starting at a dose of 200 mg/m2 per day, with intrapatient dose escalation of up to 100% for the second cycle. Doses were escalated further in subsequent cohorts, based on oral bioavailability and toxicity. RESULTS: Oral bioavailability of 50 mg/m2 amsalog was 34%. In the dose escalation phase, DLT was neutropenia; other toxicities included malaise and nausea. The MTD was 1600 mg/m2 per day for 5 days. The plasma AUC using 1600 mg/m2 by the oral route was higher than that achieved using 200 mg/m2 by the i.v. route. CONCLUSION: Amsalog can be tolerated orally on a 5-day schedule at doses up to 1600 mg/m2. The recommended dose for further evaluation is 800 mg/m2 daily for 5 days, repeated three weekly.

Quantitative structure-activity relationships (QSAR) for 9-anilinoacridines: a comparative analysis.

A new analysis of the quantitative structure-activity relationship (QSAR) of the antitumor activity of anilinoacridines against L1210 leukemia in mice and mouse toxicity is reported. QSAR have also been derived for the inhibitory activity of the anilinoacridines with tumor cells and their binding to DNA. These results are compared with reactivity with simple nucleophiles. The comparative analysis shows the importance of electron releasing substituents (in general negative coefficients with the Hammett parameter sigma+) throughout the various systems and the complete lack of hydrophobic interactions from DNA to cells to mice. The presence of steric terms suggests that a protein receptor is involved. The study shows that QSAR has an important role to play in improving the efficiency in the design of bioactive compounds and that care must be taken in the design of a set of congeners so that the necessary parameters are available to do the QSAR analysis. Our study illustrates the value of comparative QSAR in generalizing our understanding of chemical-biological interactions.

[Phase III clinical trial on domestic amsacrine in patients with acute leukemias].

OBJECTIVE: To further evaluate the efficacy and side-effects of domastic amsacrine. METHODS: Two handred and ninty-one patients with acute leukemias, including initial, relapsed and refractory cases, were treated with regimens combining the amsacrine with other antileukemic drugs. RESULTS AND CONCLUSION: The total CR rate was 43.3% in ALL and 49.0% in ANLL. The CR rates of relapsed/refractory ALL and ANLL was 28.9% and 34.4%, respectively. The side effects and toxicity of the amsacrine-based regimen were similar to that of other antileukemia regimens. The pharmacokinetic parameters of the domastic amsacrine, C12h/C6h, K21 were correlated with therapeutic effectiveness.

Plasma and cellular pharmacokinetics of m-AMSA related to in vitro toxicity towards normal and leukemic clonogenic bone marrow cells (CFU-GM, CFU-L).

Plasma and cellular pharmacokinetics of m-AMSA were investigated in 5 patients with acute leukemia, using HPLC. The pharmacokinetic data served as a guideline for in vitro toxicity tests on clonogenic bone marrow cells. m-AMSA was administered as a 3-hour intravenous infusion of 100 mg/m2. Median plasma and nucleated blood cell peak concentrations were 1.25 and 6.36 micrograms/ml followed by biphasic elimination with a median T1/2 alpha alpha of 1.6 h and 0.3 h and a median T1/2 beta of 5.0 h and 5.0 h respectively. Median plasma and cellular area under the curve (AUC) for a 24-h period amounted 6.2 micrograms.h/ml and 49.8 micrograms.h/ml respectively. In vitro cellular uptake was maximal at least within 30 minutes. No differential toxicity for CFU-GM and CFU-L was observed in relation to exposure time. Median IC50 for CFU-GM and CFU-L was 2.2, 1.8 and 1.6 micrograms/ml after incubation periods of resp. 0.08, 4 and 24 h. The corresponding m-AMSA concentration x time products to achieve 50% inhibition (IAUC50) were 0.18, 7.2 and 38.4 micrograms.h/ml, respectively. 48-h prestimulation of the clonogenic bone marrow cells with Human Placenta Conditioned Medium increased sensitivity (median 1.7 x) after 4 h incubation with mAMSA. Short exposure provides maximal, concentration-related, cellular uptake, resulting in effective inhibition of growth of clonogenic bone marrow cells.

[Phase II clinical trial of domestic amsacrine in patients with acute leukemias. Cooperative Group for Treating Acute Leukemias with Domestic m-AMSA].

118 patients with acute leukemias, including initial, relapsed and refractory cases, were treated with domestic Amsacrine (m-AMSA), singly or combined with other drugs. The total CR rate was 39.5% in ALL and 38.8% in ANLL, the response rate was 47.5% for both types of acute leukemias. The CR rate of relapsed and refractory ALL and ANLL treated with combination chemotherapy including domestic m-AMSA was 30.8% and 46.2% respectively. Domestic m-AMSA was similar to the foreign product and many other antitumor drugs in side effects and toxicity. The pharmacokinetics parameters of the drugs, C12h/C6h,K21 and Cmax were correlated with the therapeutic effectiveness.

[Study on the toxicity and antitumor activity of adriamycin-DNA and amsacrine-DNA complexes in mice].

We have compared in vitro binding of adriamycin (ADR) and amsacrine (AMSA) with DNA, the toxicity, and the antitumor activity of ADR-DNA and AMSA-DNA, after intraperitoneal (ip) injection in mice. The binding of ADR with DNA is 100-fold higher than that of AMSA with DNA. The overall toxicity of ADR-DNA is significantly lower than that of ADR. ADR-DNA is more effective than ADR against three models of S180 sarcoma (by sc, ip and i.v. inoculation into mice). The peak levels of ADR-DNA and ADR were 265 +/- 24 ng.ml-1 versus 108 +/- 16 ng.ml-1 (P < 0.01). AUC 0-12 h were 1064 +/- 84 ng.h-1 x ml-1 versus 382 +/- 27 ng.h-1 x ml-1 (P < 0.01). The levels of ADR in most of tissues and tumor after administration of ADR-DNA were higher than those after administration of ADR. Moreover, there is no difference in toxicity, therapeutic effects as well as AUC between AMSA-DNA and AMSA.

Comparison of the blood-brain barrier and liver penetration of acridine antitumor drugs.

The blood-brain barrier penetration of amsacrine and its analogs 9-([2-methoxy-4-[(methylsulfonyl)-amino]phenyl]amino)-,5-dimethyl- 4-acridine carboxamide (CI-921) and M-[2-(dimethylamino)ethyl]-acridine-4-carboxamide (AC) was measured in the barbiturate-anesthetized mouse. After intracarotid administration, AC was almost completely extracted (90%) in a single transit through the brain capillaries, whereas CI-921 (20%) and amsacrine (15%) were moderately extracted. AC is retained in the brain; no loss of AC from the brain was apparent at 1, 2, 4, or 8 min after injection. In contrast, after intraportal administration, 75% of the AC, 94% of the CI-921, and 57% of the amsacrine was extracted in a single transit through the hepatic vasculature. Rather than being retained in the mouse liver, these acridine antitumor agents show time-dependent loss (t1/2 = 10 min for amsacrine and AC, 24 min for CI-921). We conclude that unlike most antitumor agents, these acridine drugs appear to penetrate the blood-brain barrier readily.

Resistance mechanisms to topoisomerase poisons: the application of cell culture methods.

A survey is presented of two types of resistance to drugs acting on cellular topoisomerase enzymes, that occurring by altered drug transport and that occurring by altered target interaction. Particular attention is paid to the use of pairs of diagnostic drugs, one susceptible and one refractory to a particular resistance mechanism, in the determination of such resistance in cultured cells. Two pairs of drugs, each including the antitumor agent amsacrine, are used in the analysis of a number of cell lines. Also it is suggested that some normal hemopoietic precursor cells may exhibit two types of multidrug resistance, and that this should be taken into account in determining selectivity of topoisomerase-directed drugs for tumor cells.