Mitoxantrone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer

Dose-escalation study of docetaxel in combination with mitoxantrone as first-line treatment in patients with metastatic breast cancer

PURPOSE

To define the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLTs) of docetaxel in combination with mitoxantrone in patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS

Forty-one chemotherapy-naive patients with MBC (median age, 61 years) were enrolled. Thirty-eight (93%) had performance status (World Health Organization [WHO]) 0, 29 (71%) were postmenopausal, and 21 (51%) had estrogen receptor-negative tumors. Patients received escalated doses of docetaxel (75 to 100 mg/m2) on day 1 and mitoxantrone (8 to 22 mg/m2) on day 8. Treatment was repeated every 3 weeks.

RESULTS

A total of 217 chemotherapy cycles were administered. Without recombinant human granulocyte colony-stimulating factor (rhG-CSF) support, the MTD1 occurred at the first dose level (docetaxel 75 mg/m2 and mitoxantrone 8 mg/m2); DLTs were febrile neutropenia, grade 4 neutropenia lasting more than 5 days, and grade 3 diarrhea. With prophylactic rhG-CSF, the MTD2 was docetaxel 100 mg/m2 and mitoxantrone 20 mg/m2; DLTs were febrile neutropenia and grade 4 neutropenia. Nine (22%) patients developed neutropenia after the first cycle of treatment. A total of 19 episodes of febrile neutropenia (9% of the cycles) occurred during the whole period of the study; there were no toxic deaths. At high docetaxel (100 mg/m2) and mitoxantrone (> 12 mg/m2) dose levels, a significant decrease of the absolute lymphocyte number was observed; immunophenotyping revealed that all lymphocyte subpopulations were reduced. Grades 2 and 3 neurosensory toxicity occurred in six patients (15%) and one patient (2%), respectively. No cardiac toxicity was observed. Nine complete responses (22%) and 23 partial responses (56%) were achieved (overall response rate, 78%; 95% confidence interval, 62.5% to 88.8%). The median duration of response was 12.5 months, and the median time to tumor progression was 14.5 months.

CONCLUSION

The reported combination of docetaxel and mitoxantrone with G-CSF support is a safe, intensified, well-tolerated, and effective regimen as first-line treatment in patients with MBC.

Evaluation of mitoxantrone-loaded albumin microspheres following intraperitoneal administration to rats

Mitoxantrone has demonstrated therapeutic efficacy in the regional treatment of intraperitoneal malignancies. However, severe local toxicity was dose limiting. Consequently, a new injectable sustained delivery formulation of mitoxantrone has been developed: the drug was incorporated (8.2 w/w%) in highly hydrophilic albumin microspheres. In vitro drug release profile was modified by matrix crosslinking extent. The extractable amount of residual crosslinking agent (glutaraldehyde) in the microspheres was lower than 6 ppm. Mitoxantrone concentration in peritoneal fluid and plasma was determined up to 72 h after intraperitoneal administration of 30, 60 and 120 mg mitoxantrone per m2 body surface area as solution and in the form of a dispersion containing mitoxantrone-loaded microspheres to rats. Data analysis revealed sustained release of mitoxantrone from microspheres into peritoneal fluid in all dosage groups. The initial high drug levels in peritoneal fluid and plasma observed after application of mitoxantrone in the solution form were prevented by administration of the drug incorporated in microspheres. However, tumoricidal drug levels in peritoneal fluid were maintained over a comparable time span. In addition, preliminary toxicity data suggest a superior local tolerability of mitoxantrone-loaded microspheres. The dose of intraperitoneally administered mitoxantrone might be increased from 30 to 60 mg per m2 body surface area using the slow release formulation. In conclusion, the described microsphere drug delivery system for mitoxantrone might overcome dose-limiting drug toxicity.

High single dose of mitoxantrone and cytarabine in acute non-lymphocytic leukemia: a pharmacokinetic and clinical study

In a phase I-II study, the authors evaluated the intracellular pharmacokinetics, toxicity, and efficiency of a high dose of mitoxantrone given as first induction in acute non-lymphocytic leukemia. Twenty-two patients with previously untreated de novo ANLL were included and received 30 or 40 mg/m2 mitoxantrone on day 1 by intravenous infusion over 1 hour and 500 mg/m2 ara-C twice a day for 5 days. If there was no complete remission (CR), a second induction with ara-C, etoposide, and amsacrine was given. The CR rate after two courses with this regimen was 77%. Median duration of severe neutropenia was 18 days in the 30-mg/m2 group and 25 days in the 40-mg/m2 group. Two patients had fatal lung complications probably unrelated to mitoxantrone. A third patient had a possible mitoxantrone-induced reversible lung complication. In the leukemic cells, we found a high accumulation of mitoxantrone which, in contrast to the plasma concentration, remained stable during the 48 hours studied. Compared with previous results with 12 mg/m2 mitoxantrone, the AUC for intracellular concentrations versus time for the first 20 hours studied was increased by 150% to 0.638 nmol/mg cell protein x hour with 30 mg/m2 mitoxantrone and by 260% to 1.103 nmol/mg cell protein x hour with 40 mg/m2 mitoxantrone. In conclusion, a high dose of mitoxantrone results in a high intracellular exposure of the leukemic cells, which may be an advantage in improving survival of these patients.

Clinical applications of anticancer drugs targeted to topoisomerase II

Agents which 'poison' the enzyme topoisomerase II, have proven to be useful drugs for cancer treatment. Six antineoplastic drugs, which target topoisomerase II (doxorubicin, daunorubicin, idarubicin, mitoxantrone, etoposide and teniposide) are currently approved for clinical use in the United States. In this paper, the strategies and goals of cancer chemotherapy are summarized for the non-clinician. The use, pharmacology and toxicity of each of the six currently approved topoisomerase II inhibiting agents are reviewed.

A phase I trial of vinorelbine in combination with mitoxantrone in patients with refractory solid tumors

Vinorelbine (Navelbine) is a unique semi-synthetic vinca-alkaloid with a favorable safety profile that has demonstrated significant antitumor activity in patients with non-small cell lung cancer, advanced breast cancer, advanced ovarian cancer and Hodgkin's disease. The most common dose-limiting toxicity is neutropenia, while other reported toxicities are minimal. Mitoxantrone (Novantrone) is an anthracene derivative that has demonstrated antitumor activity in patients with breast cancer, ovarian cancer, acute leukemia, and lymphoma. Mitoxantrone also has a very favorable toxicity profile with significantly less nausea and vomiting, alopecia, and stomatitis as compared with anthracyclines. The dose-limiting toxicity for mitoxantrone is leukopenia. The study was designed to determine the safety and maximally tolerated dose of IV vinorelbine used in combination with a fixed dose of mitoxantrone for the treatment of patients with refractory solid tumors. Vinorelbine was administered on days 1 and 8 of the treatment regimen as a short IV infusion. The starting dose was 15 mg/m2. Mitoxantrone was administered as a 20-min infusion on day 1 only at a fixed dose of 10 mg/m2. Seventeen patients with solid malignancies were entered in the study. For personal reasons, one patient decided to discontinue the treatment after day 1 of cycle 1. Therefore, 16 patients were evaluable for toxicity. The main toxicity was myelosuppression which was dose-limiting and resulted in dose reductions and delays. The use of G-CSF had a minimal overall impact on this regimen. Stable disease was observed in three cases. In patients previously treated with chemotherapy, the maximally tolerated dose was defined as vinorelbine 20 mg/m2 on days 1 and 8 and mitoxantrone 10 mg/m2 on day 1 without growth factor support. These doses can be recommended for phase II study of the regimen as salvage treatment.

Evaluation of single-agent mitoxantrone as chemotherapy for relapsing canine lymphoma

Many chemotherapeutic regimens will induce remission in dogs with lymphoma, but almost all dogs suffer relapse. Mitoxantrone was selected for evaluation as single-agent chemotherapy for relapsing canine lymphoma based on its use in humans undergoing salvage chemotherapy for non-Hodgkin's lymphoma and its tumoricidal effect against canine lymphoma. Dogs entered into study had multicentric lymphoma, and all had been treated solely with a standard combination chemotherapy protocol. At 1st relapse, all dogs were again staged and underwent lymph node biopsy. Mitoxantrone was administered IV at 6 mg/m2 every 21 days. Dogs were evaluated for lymphadenopathy before each dose of mitoxantrone. Fifteen dogs were entered into study. The average age (+/- SEM) of the dogs studied was 7.7 +/- 0.91 years, and most dogs were large (mean +/- SEM weight, 24.44 +/- 2.15 kg). Twelve dogs (80%) had B-cell lymphoma, and 3 had T-cell lymphoma. Dogs were staged IV (n = 12) or V (n = 3). The median duration of chemotherapy before entry into the study was 98 days. Overall median duration of response after mitoxantrone chemotherapy was 21 days. Complete responses were attained in 7 of 15 dogs (47%) with a median response duration of 84 days. Nine of 15 (60%) dogs attained a complete remission with additional chemotherapy after failing mitoxantrone chemotherapy. Mild toxicities were observed after mitoxantrone administration. No adverse reactions were observed during mitoxantrone infusions. The results of this study demonstrate that mitoxantrone, as a single agent, has limited value for dogs with lymphoma at 1st relapse after conventional multidrug chemotherapy.

Etoposide: four decades of development of a topoisomerase II inhibitor

Podophyllin-containing materials have been used as folk medicines for centuries. In the 1950s, scientists began a search to identify a more effective podophyllotoxin derivative. These efforts eventually resulted in the development of a new class of antineoplastic agents which target the DNA unwinding enzyme, topoisomerase II. The history of the development of one of the first identified topoisomerase II inhibitors, etoposide, is reviewed in this paper. Critical developments in etoposide's mechanism of action, pharmacology and administration schedule are summarised. The clinical benefits of the recently marketed etoposide prodrug, etoposide phosphate (Etopophos) are also detailed. The current status of other clinically approved anticancer agents which target topoisomerase II is briefly reviewed.

Use of body surface area to calculate chemotherapeutic drug dose in dogs: II. Limitations imposed by pharmacokinetic factors

Anticancer drug dosages that specify the maximum dose and minimum dosing interval that are tolerated in a population of dogs are commonly recommended. Because the differences between the effective and toxic doses of most cancer chemotherapeutics is slight, it is important to achieve therapeutic concentrations in tumor tissues at the same time that concentrations in nontarget tissues are minimized. In order to determine the dosage regimen that will most likely accomplish these goals, similar drug concentrations must be achieved in all patients dosed according to a specific regimen. Dosing based on body surface area (BSA) is generally used in an effort to normalize drug concentrations. This is because it is well recognized that measures of many physiologic parameters that are responsible for drug disposition, including renal function and energy expenditure, can be normalized by use of BSA. However, there is substantial evidence that drug disposition is not always proportional to BSA. Differences in distribution, metabolism, and excretion pathways may preclude dose extrapolation among species or among individuals within a species based on BSA. Moreover, genetic differences in drug metabolism are well recognized in humans and in laboratory animals, and it is likely that similar differences exist among breeds of dogs. A review of the pharmacokinetic disposition of several cancer chemotherapeutics suggests that studies are needed to determine the most effective method to achieve equivalent anticancer drug concentrations in diverse veterinary patients.

Anthracyclines in haematology: pharmacokinetics and clinical studies

The activity of anthracyclines in the treatment of a wide spectrum of haematological malignancies has long been established. Differences in the pharmacokinetic and pharmacodynamic properties of these drugs have resulted in the selection of individual compounds for particular indications while the recent reformulation of anthracyclines in liposomal preparations seems likely to significantly alter their range of activity and toxicity. The problems related to cumulative cardiotoxicity secondary to anthracycline exposure can be ameliorated by the use of dexrazoxane and a number of agents may prove to have a role in altering their cellular resistance to their cytotoxic actions.

Quantitative confocal spectral imaging analysis of mitoxantrone within living K562 cells: intracellular accumulation and distribution of monomers, aggregates, naphtoquinoxaline metabolite, and drug-target complexes

Confocal spectral imaging (CSI) technique was used for quantitative analysis of the uptake, subcellular localization, and characteristics of localized binding and retention of anticancer agent mitoxantrone (MITOX) within human K562 erythroleukemia cells. The CSI technique enables identification of the state and interactions of the drug within the living cells. Utilizing this unique property of the method, intracellular distributions were examined for monomeric MITOX in polar environment, MITOX bound with hydrophobic cellular structures, naphthoquinoxaline metabolite, and nucleic acid-related complexes of MITOX. The features revealed were compared for the cells treated with 2 microM or 10 microM of MITOX for 1 h and correlated to the known data on antitumor action of the drug. MITOX was found to exhibit high tendency to self-aggregation within intracellular media. The aggregates are concluded to be a determinant of long-term intracellular retention of the drug and a source of persistent intracellular binding of MITOX. Considerable penetration of MITOX in the hydrophobic cytoskeleton structures as well as growing accumulation of MITOX bound to nucleic acids within the nucleus were found to occur in the cells treated with a high concentration of the drug. These effects may be among the factors stimulating and/or accompanying high-dose mitoxantrone-induced programmed cell death or apoptosis.

Localization and molecular interactions of mitoxantrone within living K562 cells as probed by confocal spectral imaging analysis

Studying mechanisms of drug antitumor action is complicated by the lack of noninvasive methods enabling direct monitoring of the state and interactions of the drugs within intact viable cells. Here we present a confocal spectral imaging (CSI) technique as a method of overcoming this problem. We applied this method to the examination of localization and interactions of mitoxantrone (1, 4-dihydroxy-5, 8-bis-[([2-(2-hydroxyethyl)-amino]ethyl)amino]-9,10-anthracenedione dihydrochloride), a potent antitumor drug, in living K562 cells. A two-dimensional set of fluorescence spectra of mitoxantrone (MITOX) recorded with micron resolution within a drug-treated cell was analyzed to reveal formation of drug-target complexes and to create the maps of their intracellular distribution. The analysis was based on detailed in vitro modeling of drug-target (DNA, RNA, DNA topoisomerase II) interactions and environmental effects affecting drug fluorescence. MITOX exposed to aqueous intracellular environment, MITOX bound to hydrophobic cellular structures, complexes of MITOX with nucleic acids, as well as the naphtoquinoxaline metabolite of MITOX were simultaneously detected and mapped in K562 cells. These states and complexes are known to be immediately related to the antitumor action of the drug. The results obtained present a basis for the subsequent quantitative analysis of concentration and time-dependent accumulation of free and bound MITOX within different compartments of living cancer cells.

[Mitoxantrone-induced acute left heart failure after intrapleural administration]

A 79-year-old female was admitted to our hospital because of a malignant pleural effusion following mastectomy 4 years ago. In the patient's history arterial hypertension and previous inferior myocardial infarction have been known. Two doses of 20 mg mitoxantrone were installed intrapleurally at an interval of 4 weeks. Six hours after the second mitoxantrone application and the patient had increasing dyspnea with consecutive left heart failure, pulmonary congestion, and a drop of blood pressure. The white-cell count was 14800/mm3. The levels of creatinine phosphokinase (CPK), lactate dehydrogenase (LDH) and serum aspartate aminotransferase (SGOT) were in the normal range. Transthoracic echocardiography showed concentric left ventricular hypertrophy and a markedly decreased fractional shortening, but no left ventricular dilatation. The electrocardiogram showed newly appeared down-sloping ST-segments and inverted T-waves. Clinical recovery was achieved after 6 days by application of oxygen, dobutamine and furosemide followed by angiotensin converting enzyme inhibition and digitalis. In the echocardiographic control examination 14 days later left ventricular function had normalized. The changes of electrocardiogram normalized 4 weeks later.

Mitoxantrone-induced DNA strand breaks in cell-cultures of malignant human astrocytoma and glioblastoma tumors

In this study mitoxantrone (Mtx) induced DNA strand breaks were measured with the alkaline elution technique in short term cell cultures derived from human gliomas. Glioblastomas or astrocytomas from 5 patients who underwent intracranial surgery were cultured and incubated i h with different concentrations of Mtx (0, 0.01, 0.1 and 1.0 microgram/ml). The alkaline elution method was modified to measure DNA lesions in human gliomas. Mtx induced DNA strand breaks in a dose dependent manner in all cell cultures tested. There was a linear increase of DNA strand break frequency induced by Mtx between 0.01-1.0 microgram/ml. concerning these in vitro data, Mtx might be potentially useful for the treatment of patients with malignant brain tumors.

Physicochemical properties, cytotoxic activity and topoisomerase II inhibition of 2,3-diaza-anthracenediones

The physicochemical, cytotoxic and pharmacological properties of 2,3-diaza-anthracenedione derivatives were examined to gain insight into the structure-activity relationships in this class of compounds. Spectrophotometric, chiroptical and voltammetric measurements were performed, along with cell cytotoxicity, alkaline elution, topoisomerase II-mediated DNA cleavage and cellular drug-uptake determination. In comparison with classic anthracenediones such as mitoxantrone and ametantrone, the aza derivatives were characterized by less negative reduction potentials, lower affinity for DNA and modified geometry of intercalation. The biological effects of the new compounds were also profoundly affected by bioisosteric N for C replacement. Stimulation of topoisomerase II-mediated DNA cleavage was not observed, whereas other mechanisms of cell cytotoxicity, possibly involving oxidative DNA damage appeared to be operative. The inability to generate protein-associated strand breaks could be explained by an unfavorable orientation of the drug in the intercalation complex rather than by a reduced binding to DNA. Geometry of drug intercalation may have a critical influence on the formation of the ternary complex. In turn, the onset of a different DNA-damaging pathway is likely to be related to easy redox cycling of the 2,3-diaza-substituted anthracenedione derivatives, which could produce radical species to a remarkably greater extent than could the carbocyclic parent drugs.

Comparative pharmacokinetic and cytotoxic analysis of three different formulations of mitoxantrone in mice

Two liposomal formulations of mitoxantrone (MTO) were compared with the aqueous solution (free MTO) in terms of their pharmacokinetic behaviour in ICR mice and cytotoxic activity in a nude mouse xenograft model. The three different formulations of MTO [free MTO, phosphatidic acid (PA)-MTO liposomes, pH-MTO liposomes] were administered intravenously (three mice per formulation and time point) at a dose of 4.7 micromol kg(-1) for free MTO, 6.1 micromol kg(-1) for PA-MTO and 4.5 micromol kg(-1) for pH-MTO. The concentrations of MTO were determined using high-performance liquid chromatography (HPLC) in blood, liver, heart, spleen and kidneys of the mice. Additionally, the toxicity and anti-tumour activity of MTO was evaluated in a xenograft model using a human LXFL 529/6 large-cell lung carcinoma. The dose administered was 90% of the maximum tolerated dose (MTD) of the corresponding formulation (8.1 micromol kg(-1) for free MTO, 12.1 micromol kg(-1) for PA-MTO and pH-MTO). The pharmacokinetic behaviour of PA-MTO in blood was faster than that of free MTO, but the cytotoxic effect was improved. In contrast, pH-MTO showed a tenfold increased area under the curve (AUC) in blood compared with free MTO, without improvement of the cytotoxic effect. This discrepancy between the pharmacokinetic and cytotoxic results could be explained by the fact that MTO in pH-MTO liposomes remains mainly in the vascular space, whereas MTO in PA-MTO liposomes is rapidly distributed into deep compartments, even more so than free MTO.

Mutagenicity of anticancer drugs that inhibit topoisomerase enzymes

Topoisomerases are enzymes that catalyse the transient breakage and rejoining of either one (topo I) or two (topo II) DNA strands, to allow one strand to pass through another and prevent unresolvable tangles during processes such as DNA replication. A number of important clinical antitumour agents act through inhibition of topo II enzymes, while some topo I inhibitors appear likely to enter clinical use. Although these chemicals do not covalently interact with DNA, they have strong mutagenic potential, generally causing events at the level of the chromosome rather than that of the gene. Most are recombinogens, may affect gene expression and can also lead to aneuploidy through effects on chromosome segregation. Most topo I and topo II inhibitors primarily cause mutagenic events associated with the replication fork. However, at least in mitotic chromosomes, topo II enzymes are located at the base of chromosome loops, and topo II inhibitors may facilitate subunit exchanges, leading to major deletions and illegitimate recombinational events. There is evidence that programmed cell death provides an alternative pathway to mutagenesis following treatment by either topo I or topo II inhibitors. The final fate of the cell will result from a balance between these two processes.

Salen-anthraquinone conjugates. Synthesis, DNA-binding and cleaving properties, effects on topoisomerases and cytotoxicity

A series of amidoethylamino-anthraquinone derivatives bearing either one or two salen (bis(salicylidene)ethylenediamine) moieties complexed with CuII or NiII have been synthesized, and their DNA-binding and cleaving properties examined. The effects of the mono- and di-substituted anthracenedione-salen conjugates on DNA cleavage mediated by topoisomerases I and II have also been determined, as well as their cytotoxicity toward human KB cells. The anthraquinone-salen. NiII conjugates bind to GC-rich sequences in DNA, but do not cleave the macromolecule. By contrast, the anthraquinone-salen. CuII hybrids do not recognize particular nucleotide sequences but efficiently induce single-strand breaks in DNA after activation. The 5,8-dihydroxy-anthraquinone conjugates are more cytotoxic and more potent toward topoisomerase II than the non-hydroxylated analogues, but they are less cytotoxic than the salen-free anthraquinones. The attachment of a salen. CuII complex to the anthraquinone chromophore can confer DNA cleaving properties in vitro, but this is at the expense of cytotoxic activity. Anthraquinone-salen. CuII complexes may find useful employ as footprinting probes for investigating ligand-DNA interactions.

Mitoxantrone immunotherapy in multiple sclerosis

Mitoxantrone, a cytotoxic agent recently developed, was subsequently found a very potent immunosuppressor. Experimental data in experimental allergic encephaloymyelitis demonstrated a dramatic suppression of both active and passive forms. Immune effects concern cellular and humoral components and are particularly persistent. B cell subset is preferentially deleted. Suppressor cells are relatively spared and suppression becomes dominant. In cancer therapy, the main advantages of mitoxantrone are a definitely better immediate tolerance and very low delayed adverse reactions (carcinogenicity, teratogenicity, impact on reproductive organs). Given its major immunosuppressive activity and its better tolerance, mitoxantrone was a potential candidate for multiple sclerosis therapy. Several clinical trials have confirmed the remarkable efficacy of mitoxantrone to reduce both attack and progression rates. Unfortunately the cardiotoxicity was found more frequent than expected and limits the maximum cumulative dose to 120 mg/m2. Mitoxantrone, when employed properly, may be useful in patients with frequent and disabling excerbations and/or rapidly progressing disability. It must be kept in mind that multiple sclerosis is a chronic disease, and that the benefit is limited to the period of administration of any treatment.

Introductory remarks: immunosuppressive and immunomodulating drugs, where and how do they act?

Immunotherapies used in multiple sclerosis are reviewed. The mechanisms of action supporting their clinical application are described according to our current understanding. Immune treatments can be divided into three groups: (1) cytostatic and cytotoxic immunosuppressants which block the cell cycle of immunocompetent cells and/or provoke their deletion; (2) immunomodulators which specifically interfere in cellular or humoral immune mechanisms; (3) immunoregulators which restore immunodeficient states but have also immunosuppressive properties at the same time. Numerous attempts have been made to correct almost all abnormal immune mechanisms underlying disease progression. The results of those clinical trials are reviewed. Recent studies have demonstrated that a severe, unspecific and sustained immunosuppression markedly downregulates the clinical and pathological activity of the disease. Unfortunately, serious delayed adverse effects prevent a long-term administration. Recent specific immunomodulators with an acceptable toxicity have provided modest but unquestionable benefit on the attack rate and MRI lesion burden. No clear effect on progression has been demonstrated to date. There is still much work to be done to improve the efficacy of our current therapies on the attack rate and particularly on the progression. Several promising new compounds are already under evaluation. Another approach is combination therapies which will certainly become critical in MS like in other autoimmune diseases.

Hyperthermia-enhanced effectiveness of mitoxantrone in an experimental rat tumour

The influence of local hyperthermia (HT) on Mitoxantrone (MITOX) effectiveness was studied in an experimental rat tumour. R-1 rhabdomyosarcomas were treated with MITOX (5 mg/kg ip), HT (43 degrees C for 1 h) or combinations applied at various time intervals up to 24 h. Tumour growth delay and tumour cell clonogenicity were assessed in correlation with the pharmacokinetics in blood plasma and with MITOX-concentrations in tumour tissue. Combined treatments were more effective than expected on the basis of simple addition of effects of single treatments. With increasing time intervals between treatments up to 8 h, an increase in effectiveness was observed. Unfortunately, treatment with an 8-h interval resulted in a high mortality: 80% of the rats died with 5-10 days after treatment. Treatment with a 3-h interval between MITOX and HT was the most effective combination resulting in the highest therapeutic ratio. Even local tumour controls (14/18 rats) were observed. These enhanced effects were associated with a higher MITOX-concentration in the fraction of intact cells recovered from tumours. However, no differences were observed in MITOX-concentration in total tumour tissue nor in plasma concentrations. In conclusion, timing between MITOX and HT is important for drug availability, for interaction of the two modalities to increase damage in tumour cells and for limiting the toxicity to normal tissues.

Local hyperthermic treatment does not enhance mitoxantrone effectiveness for responses of a rat solid tumour regrowing after irradiation

Tumours regrowing after irradiation may respond differently to chemo-hyperthermia as compared to non- irradiated tumours. In this study, the efficacy of combined treatment of previously irradiated tumors with mitoxantrone and local hyperthermia (HT) was investigated. Rat R-1 tumours were irradiated with dose fractions of 5Gy X-rays applied on 4 consecutive days. Animals were retreated with mitoxantrone (5mg/kg i.p.), HT (1 h at 43 degrees C) or mitoxantrone + HT (3-h interval) on day 9 after the start of irradiation when tumour volumes were decreasing, or on day 16 when tumour volumes were increasing again. Pharmacokinetics were studied in relation to tumor cell survival and tumour growth delay. No Ht=induced changes in the pharmacokinetics of mitoxantrone were observed. The data on clonogenic survival correlated well with these findings and combined treatment were not more effective than mitoxantrone alone. In the treatment schedule applied, HT did not induce pharmacokinetic changes in irradiated tumours leading to an enhanced cytotoxicity of mitoxantrone. The HT- enhanced effectiveness of the drug observed in non- irradiated tumours is much less in pre-irradiated tumours. Responses of regrowing tumours to combined chemo- hyperthermia depend in a complex way on the stage of regrowth and on the treatment schedule.

DNA recognition by two mitoxantrone analogues: influence of the hydroxyl groups

The clinically useful anticancer drug mitoxantrone intercalates preferentially into 5'-(A/T)CG and 5'-(A/T)CA sites on DNA. The 5,8 hydroxyl substituents on its anthracenedione chromophore are available to interact with the double helix. Footprinting experiments with two anthraquinone derivatives structurally related to mitoxantrone and ametantrone have been undertaken to assess the influence of the hydroxyl groups on the DNA recognition process. The results confirm that they do play a role in the recognition of preferred nucleotide sequences and suggest that the binding of anthraquinones to a 5'-(A/T)CG site is dependent on the presence of the 5,8 hydroxyl substitutes whereas binding to 5'-(A/T)CA sites appears to proceed just as well without them.

Effects of intrapleural mitoxantrone and mepacrine on malignant pleural effusion--a randomised study

30 patients with malignant pleuritis were randomised to be treated, either with intrapleural instillation of mepacrine chloride or with mitoxantrone. The patients were evaluated with chest X-ray and a symptom questionnaire during a follow-up period of 12 weeks. Mitoxantrone levels in the pleural space and plasma were measured at different time points in some of the patients. High concentrations of mitoxantrone were found in the pleural fluid while the plasma concentrations were low, giving a plasma/intracavity ratio generally of less than 1:60. The chest X-rays showed excellent results for both treatment modalities. However, the patients treated with mepacrine chloride experienced greater discomfort with fever and pain, and those treated with mitoxantrone reported significantly less dyspnoea and less asthenia after 4 weeks. We conclude that both treatments are equally effective in preventing the recurrence of malignant effusion. However, mitoxantrone seems to have further advantages when it comes to improving the quality of life.

Mitoxantrone is effective in treating childhood T-cell lymphoma/T-cell acute lymphoblastic leukemia

BACKGROUND

T-cell malignancies in childhood are highly malignant diseases usually treated with intensive multidrug chemotherapy. In these regimens, anthracyclines, which are considerably cardiotoxic, are used. Mitoxantrone is structurally related to the anthracyclines, but it is considered to be less cardiotoxic. Therefore, the effectiveness of mitoxantrone in treating childhood T-cell malignancies was studied.

METHODS

Fourteen newly diagnosed children with T-cell malignancies (12 T-cell non-Hodgkin's lymphoma, 2 T-cell acute lymphoblastic leukemia) initially were treated with one bolus injection of mitoxantrone, 12 mg/m2 intravenously, 1 week before standard induction therapy was begun. The effect of mitoxantrone was evaluated at Day 8, just before standard induction therapy was begun.

RESULTS

Of 12 evaluable patients, 11 had significant positive responses with regard to the size of the primary tumor, the size of the involved peripheral lymph nodes, and the presence of lymphoblasts in the peripheral blood. The toxicity of mitoxantrone was mild.

CONCLUSIONS

Mitoxantrone is effective in treating childhood T-cell malignancies. Its efficacy needs to be compared with the anthracyclines in a future randomized study.

AQ4N: an alkylaminoanthraquinone N-oxide showing bioreductive potential and positive interaction with radiation in vivo

AQ4N (1,4-bis([2-(dimethylamino-N-oxide)ethyl]amino)5,8-dihydroxy- anthracene-9,10-dione) is a novel alkylaminoanthraquinone N-oxide which, on reduction, forms a stable DNA affinic cytotoxic compound AQ4. The in vivo anti-tumour efficacy of AQ4N was investigated in B6D2F1 mice bearing the T50/80 mammary carcinoma. The effect of the drug was evaluated in combination with hypobaric hypoxia and with radiation (single and multiple fractions). Systemic toxicity was assessed by weight loss post treatment. This was low for AQ4N and was less than that obtained with the bioreductive drugs, RSU 1069 (1-[3-aziridinyl-2-hydroxypropyl]-2-nitroimidazole) and SR 4233 (Tirapazamine, 3-amino-1,2,4-benzotriazine-1,4-dioxide). The anti-tumour effect of AQ4N was potentiated in vivo by combination with hypobaric hypoxia with a dose enhancement ratio of 5.1. This is consistent with the proposal that AQ4N was reduced in vivo to AQ4, resulting in enhanced anti-tumour toxicity. When AQ4N (200 mg kg-1) was combined with single dose radiation (12 Gy) the drug was shown to have an additive interaction with radiation. This was obtained even if the drug was administered from 4 days before to 6 h after radiation treatment. Equivalent anti-tumour activity was also shown when both AQ4N (200 mg kg-1) and radiation (5 x 3 Gy) were administered in fractionated schedules. In conclusion, AQ4N shows significant potential as a bioreductive drug for combination with fractionated radiotherapy.

A phase III randomized trial of cyclophosphamide, mitoxantrone, and 5-fluorouracil (CNF) versus cyclophosphamide, adriamycin, and 5-fluorouracil (CAF) in patients with metastatic breast cancer

One hundred patients with metastatic breast cancer were randomly selected to receive combined chemotherapy treatment with adriamycin (50 mg/m2) or mitoxantrone (12 mg/m2) associated with 5-fluorouracil (600 mg/m2) and cyclophosphamide (600 mg/m2) administered intravenously every 21 days with a maximum of ten cycles. All patients included in this study were under 75 years of age and had ECOG performance status of less than 4. They had not been treated previously with chemotherapy for metastatic disease. Patients treated with adjuvant chemotherapy, which could not have included anthracyclines, had to have relapsed at least 12 months after the completion of therapy. There were no statistically significant differences in pretreatment characteristics or metastatic disease location between the two groups. Ninety-four patients were assessable for response. No differences were observed in response rate or in survival between the groups. The response rate (complete response (CR) and partial response (PR)) was 68% (13% CR and 55% PR for CAF; 0% CR and 68% PR for CNF). Median survival for all patients was 19 months (18 months with CAF and 19 months with CNF). All patients were assessable for toxicity. There were no differences in gastrointestinal and cardiac toxicity. More grade I-II hematologic toxicity episodes (p < 0.001) and treatment delays (p = 0.05) due to leucopenia were observed with the CNF group, and more grade III alopecia (p < 0.001) was observed with the CAF group. Patients received further therapeutic manoeuvres after finishing the study with a sequential treatment consisting of hormonal therapy and chemotherapy with mitomycin (M) -vinblastine (Vbl) (M 10 mg/m2 day 1, Vbl 5 mg/m2 days 1, 15 and 29; maximum 5 cycles). This chemotherapy treatment was received by 32 patients, with a response rate of 34% and grade III-IV hematologic toxicity of 37%. Treatment with CNF can be considered a good alternative to CAF for first-line treatment of metastatic breast cancer. M-Vbl treatment is useful as second-line treatment in patients with prior adriamycin exposure.

Mitoxantrone, chlorambucil and prednisolone in the treatment of non-Hodgkin's lymphoma

The management of low grade lymphoma, both de novo and relapsed disease, is a contentious area in which there has been little real progress in recent years. Regimens which increase the intensity of treatment may accelerate the response but are inevitably associated with greater toxicity. This cannot be justified in a disease whose median survival is between 4 and 10 years and where the median age at presentation is 57. We have assessed the response of 144 patients treated with a combination of mitoxantrone, chlorambucil and prednisolone in a heterogeneous group with lymphoma, both de novo and relapsed disease. In the subgroup with low grade relapsed/refractory disease our results suggest that this combination is clinically effective, low in toxicity and suitable for the outpatient management of this usually elderly patient population.

Synthesis and structural elucidation of biliary excreted thioether derivatives of mitoxantrone

1. Hplc-MS coupling has been used for the identification of thioether derivatives of the anticancer agent mitoxantrone in the bile of pig. 2. Three biologically relevant new thioether derivatives of mitoxantrone have been synthesized by a horseradish peroxidase-catalysed reaction. 3. The thioether derivatives have been characterized by means of ion-spray tandem mass spectrometry and nmr spectrometry including two-dimensional techniques. 4. The carbon-sulphur bond formation takes place at the hydroquinone moiety of the anthraquinone skeleton pointing to the importance of a tautomeric equilibrium between different species of the oxidized drug. 5. The occurrence of the synthesized compounds in biological systems suggests a metabolic pathway that may be relevant for the cytotoxicity of mitoxantrone (oxidative activation).

Phase I trial of mitoxantrone and granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with advanced solid malignancies

PURPOSE

To determine the maximally tolerated dose (MTD) and pharmacokinetics of high-dose mitoxantrone and document the toxicities and side effects of mitoxantrone when administered with GM-CSF.

PATIENTS AND METHODS

Twenty-three patients with advanced solid tumors were entered into a phase I and pharmacokinetic study. Mitoxantrone was administered at doses of 12, 21, 28, 32, 37, and 48 mg/m2 on day 1; GM-CSF (5 micrograms/kg once or twice daily) was administered on days 2 to 14. Therapy was repeated every 3 weeks. Dose escalation continued in sets of three patients until the dose limiting toxicity (DLT) was observed. The DLT was based on hematologic, non-hematologic, and cardiac toxicity, and delay of therapy by more than 1 week due to toxicity. Plasma samples were assayed for mitoxantrone concentrations using high performance liquid chromatography (HPLC).

RESULTS

Twelve patients required either mitoxantrone dose reductions or delays. DLT of neutropenia was observed at a mitoxantrone dose of 48 mg/m2/day. Therefore, we conclude the MTD was 37 mg/m2/day. Myelosuppression appeared to be cumulative. Two patients were withdrawn from the study due to a drop in left ventricular ejection fraction (LVEF). Two of 23 patients experienced a partial response. The mean area under the curve (AUC) and peak mitoxantrone levels increased linearly with dose; triexponential elimination of mitoxantrone was observed. No statistically significant correlation was observed between either peak mitoxantrone level or AUC and duration of absolute neutrophil count (ANC) < 500/mm3.

CONCLUSION

The use of GM-CSF allows administration of mitoxantrone at a dose greater than three times that given in standard therapy; treatment is well tolerated. Further studies are needed to determine whether mitoxantrone has cumulative cardiac or hematologic toxicity.

Liposomes as carriers of cancer chemotherapy. Current status and future prospects

Chemotherapy is a modality of cancer therapy that needs much improvement. Development of a new chemical entity is very costly and time consuming, but improvements in delivery of existing agents may yield more rapid clinical results. Liposomes and other lipid-based drug delivery systems have the advantage, in this context, of utilising no new chemical entities. In terms of mechanism of action, tumour targeting has been the focus of much work in liposomal drug delivery. The recent development of liposomes with longer circulation times has led to improved tumour targeting in animal studies. Other mechanisms of action, such as release from drug depot formulations, heat-triggered local drug release, and transfection of genetic materials, may prove to be useful in humans. Liposomal formulations of more than a dozen antineoplastic agents have shown promise in vitro and in animal models. Somewhat mundane, but nevertheless crucial, issues of medical rationale and formulation engineering, and commercial considerations, have slowed testing in patients with cancer. However, 3 antineoplastic agents, doxorubicin, daunorubicin and cytarabine, are in advanced stages of clinical testing in humans. One or more of these should prove to be a medically useful and commercially viable product within the next few years.

A comparison of free radical formation by quinone antitumour agents in MCF-7 cells and the role of NAD(P)H (quinone-acceptor) oxidoreductase (DT-diaphorase)

Electron paramagnetic resonance (EPR/ESR) spin trapping studies with DMPO revealed that purified rat liver NAD(P)H (quinone-acceptor) oxidoreductase (QAO) mediated hydroxyl radical formation by a diverse range of quinone-based antitumour agents. However, when MCF-7 S9 cell fraction was the source of QAO, EPR studies distinguished four different interactions by these agents and QAO with respect to hydroxyl radical formation: (i) hydroxyl radical formation by diaziquone (AZQ), menadione, 1AQ; 1,5AQ and 1,8AQ was mediated entirely or partially by QAO in MCF-7 S9 fraction; (ii) hydroxyl radical formation by daunorubicin and Adriamycin was not mediated by QAO in MCF-7 S9 fraction; (iii) hydroxyl radical formation by mitomycin C was stimulated in MCF-7 S9 fraction when QAO was inhibited by dicumarol; (iv) no hydroxyl radical formation was detected for 1,4AQ or mitoxantrone in MCF-7 S9 fraction. This study shows that purified rat liver QAO can mediate hydroxyl radical formation by a variety of diverse quinone antitumour agents. However, QAO did not necessarily contribute to hydroxyl radical formation by these agents in MCF-7 S9 fraction and in the case of mitomycin C, QAO played a protective role against hydroxyl radical formation.

In vitro evaluation of acute effects of mitoxantrone (Novantrone) in rat and guinea pig atria

Since guinea pig and rat atria have been used as models to study acute anthracycline-induced cardiotoxicity, experiments were carried out in these preparations to evaluate possible acute cardiac effects mediated by mitoxantrone (MTX). After a latency period of approximately 90 min, MTX (10(-5)-10(-4) M) promoted a concentration-related and time-dependent decrease of spontaneous rate in guinea pig atria. A similar but less intense effect after a longer latency interval was observed in rat atria. In this preparation, MTX (10(-5)-10(-4) M) incubated up to 150 min., induced a gradual competitive beta-adrenergic blocking effect on the positive chronotropic action of isoproterenol. This was characterized by a progressive decline of pD2 values without altering Emax. A similar and stronger effect was found in isolated guinea pig atria incubated under same conditions with MTX, except that 10(-4) M exposed for 150 min. was able to depress the Emax to isoproterenol by 21.2%. In addition, MTX (10(-4) M) in this model promoted a non-competitive antagonistic effect on the chronotropic action of histamine. These data are compatible with the idea that MTX could induce cardiac acute effects qualitatively similar to but of lower potency than those produced by doxorubicin in these two models. In addition, guinea pig atria seemed to display higher sensitivity to MTX compared to rat atrial preparations.

Phase I-II intraperitoneal mitoxantrone in advanced pretreated ovarian cancer

36 previously treated patients (25 with anthracyclines) with advanced epithelial ovarian cancer have been treated with intraperitoneal (i.p.) mitoxantrone (M) at increasing doses. The response was evaluated through repeated laparoscopy with multiple biopsies and serial measurement of Ovarian Cancer Antigen 125 (CA 125); 11/36 patients had a complete (6 patients) or partial (5 patients) response. Toxicity (both local and general) was observed starting from 25 mg/m2 of M per cycle. The amount of drug reaching systemic circulation was monitored by measuring M plasma value after i.p. treatment. This study showed wide variations in serum levels obtained after i.p. doses ranging from 23 to 36 mg/m2. The area under the curve (AUC) of mitoxantrone plasma samples, did not correlate with the i.p. administered dose. Conversely, a correlation seems to exist between the plasma AUC and the responder status. Patients who showed clinical responses to i.p. treatment with mitoxantrone had AUCs and plasma peak levels of the drug that were significantly higher than those in non-responders (P = 0.03, Fisher's exact test).

Comparison of acute effects of mitoxantrone and doxorubicin in guinea-pig atria

1. The acute effects of doxorubicin (DOX) and mitoxantrone (MTX) on basal rate and on positive chronotropic activity induced by 1-noradrenaline (1-NA) were investigated in isolated guinea-pig atria. 2. DOX (10(-5)-10(-4)M) progressively depressed atrial rate after a short latency period. Only 10(-4) M MTX reduced the spontaneous frequency after 120 and 180 min incubation. This effect was significantly lower to that elicited by DOX (10(-4)M). 3. Atropine (1.5 x 10(-6) M) and reserpine pretreatment did not affect the negative chronotropic action induced by DOX or MTX. 4. DOX (10(-5)-10(-4) M) produced a significant reduction of the maximal chronotropic response (Emax) to 1-noradrenaline (1-NA) after 60, 120 and 180 min of exposure. 5. MTX (10(-5)-10(-4) M) after 60 and 120 min incubation induced a beta-adrenergic, concentration- and time-dependent, competitive blocking effect. After 180 min of exposure, MTX (10(-4) M) reduced the Emax to 1-NA which was of less magnitude to that produced by DOX (10(-4) M). 6. Although both DOX and MTX depressed spontaneous and 1-NA induced chronotropic activity, MTX effects were of a slower onset and development compared to those exerted by DOX.

Lack of involvement of reactive oxygen in the cytotoxicity of mitoxantrone, CI941 and ametantrone in MCF-7 cells: comparison with doxorubicin

The MCF-7 cell S9 fraction and whole MCF-7 cells can mediate one-electron-redox cycling of doxorubicin, giving rise to concomitant oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH), formation of a drug semiquinone free radical, consumption of molecular oxygen and formation of superoxide anions and hydroxyl radicals. Doxorubicin redox cycling was consistent with DNA strand breakage and cell kill in MCF-7 cells. In contrast, no evidence for redox cycling was found for mitoxantrone (MIT), CI941 or ametantrone (AMET) in MCF-7 cells. Despite the absence of redox cycling, the CI941, MIT, and AMET concentrations resulting in 50% mortality (LC50; 1.5 x 10(-10), 5.2 x 10(-9) and 1.2 x 10(-6) M, respectively) of MCF-7 cells were lower than that of DOX (3.0 x 10(-6) M). Furthermore, the higher cytotoxicity of MIT and CI941 as compared with AMET or DOX was associated with greater efficiency in inducing DNA strand breakage in MCF-7 cells as determined by alkaline elution. Since MIT and CI941 proved to be the most potent DNA-damaging and cytotoxic agents in this study, the ability of DOX to undergo redox cycling does not appear to confer increased cytotoxic potential on this agent. The present study revealed several important aspects with regards to the structural modification of anthraquinone antitumour agents. Firstly, the C1 and C4 positioning of the hydroxyethylamino side chains on MIT, CI941 and AMET is associated with a lack of flavin reductase-mediated activation of these agents. Secondly, the possession of a C5 or C8 aromatic hydroxyl group appears to be intimately involved in the enhanced DNA strand breakage and cytotoxic potency of MIT and CI941, since AMET does not possess these groups. These findings indicate that future development of quinone antitumour agents should concentrate on compounds that do not undergo redox cycling but do possess aromatic hydroxyl groups, since the latter appear to be responsible for the enhanced cytotoxicity of MIT and CI941.