Protective effect of the bispiperazinedione ICRF-187 against doxorubicin-induced cardiac toxicity in women with advanced breast cancer

The next generation: new chemotherapy agents for the 1990s

The progress in cancer chemotherapy since the 1940s has been tremendous with over 40 cytotoxic agents, excluding hormones, that have undergone clinical trials and been approved by the Food and Drug Administration (FDA). Preclinical drug development and clinical trials have made this progress possible. Several new agents that are either undergoing clinical trials or have recently been approved by the FDA include idarubicin, ICRF-187, piroxantrone, all-trans-retinoic acid, fludarabine phosphate, taxol, and suramin.

Current research in side effects of high-dose chemotherapy

The toxicities of chemotherapy continue to hamper dose escalation of specific chemotherapeutic agents. The impact of dose intensification upon survival will be assessed as clinical studies continue. Strategies to support chemotherapy dose intensification include BMT, use of CSFs and antiemetic drug combinations. Advances in symptom management will hopefully enhance quality of life for patients, whereas the development of chemoprotectant agents may allow specific organ toxicities to be avoided.

Managing breast cancer in an outpatient setting

The treatment of advanced breast cancer has undergone relatively little change in the past decade. Reasons for such a static situation are the sobering realization that even effective chemotherapeutic regimens have had a minor impact on survival, and the paucity of new effective agents that have been introduced since initial combination treatments. Based in part on this lack of progress, in recent years dose-intensification in search of a curative strategy has been widely adopted. Its role remains to be defined, but ultimately it is likely to be relegated to situations where tumor burdens have been effectively reduced. This reduction in burden may not currently be feasible in many advanced presentations. Outpatient efforts will therefore focus on the following: 1) employing single agents optimally (e.g. infusion 5-fluorouracil), 2) using regimens which integrate new drugs with activity (e.g. taxol), and 3) testing measures which may improve the quality of life (e.g. bisphosphonates in the presence of bone metastases). Although one cannot approach the treatment of advanced breast cancer with the (misplaced) optimism of two decades ago, the expanded armamentarium currently available should lead to a more rational application of chemotherapy. Treatments will increasingly be based on the biology of the cancer, and on the therapeutic index and action of the drugs.

Phase I study of doxorubicin, ICRF-187 and granulocyte/macrophage-colony-stimulating factor

A group of 16 patients with advanced malignancy were entered on a phase I trial of escalating doses of doxorubicin with ICRF-187 for cardioprotection and granulocyte/macrophage-colony-stimulating factor (GMCSF) for bone marrow protection. Patients received intravenous ICRF-187 (dose ratio 20:1 ICRF-187:doxorubicin) 30 min prior to doxorubicin. GMCSF at a dose of 15 micrograms kg-1 day-1 was self-administered subcutaneously on days 3-14 of the cycle. Doxorubicin was administered every 21 days. Substantial hematological and non-hematological toxicity was seen. Fever, malaise, and pulmonary symptoms, thought to be due to GMCSF, were not eliminated by reduction in the GMCSF dose to 10 or 5 micrograms kg-1 day-1. Severe hematological toxicity was seen despite GMCSF administration and it was not possible to escalate the doxorubicin dose above 72 mg/m2 with this combination. Dose escalation of doxorubicin may be more feasible with the use of other growth factors or growth factor combinations.

Reducing doxorubicin cardiotoxicity in the rat using deferred treatment with ADR-529

The purpose of this study was to evaluate the optimal timing of ADR-529 administration to protect rats treated with doxorubicin (DXR) against drug-induced cardiotoxicity. Complete electrocardiographic monitoring (QRS complex, S alpha T segment and T wave) and the histopathological analysis of cardiac tissue were used to assess the degree of heart damage produced in female rats treated with ten i.v. doses of 1 mg/kg DXR over a period of 15 weeks; body-weight increase and survival were also analyzed to evaluate the toxicity of treatments. Cardiac alterations induced by DXR were compared with those occurring in animals receiving 20 mg/kg i.v. ADR-529 at 30 min prior to DXR administration, starting at the first, third, or sixth DXR dose and given until the end of the study (15th week). Rats treated with DXR were severely cardiomyopathic, showing progressive and irreversible ECG alterations (QRS-complex and S alpha T-segment widening and T-wave flattening) and marked degeneration of the myocardium (myocyte vacuolation, myofibrillar loss, and endomyocardial fibrosis). The most effective cardiac protection was provided by the administration of ADR-529 beginning with the first or third DXR dose. Delaying treatment with ADR-529 until the sixth DXR dose resulted in a significant reduction in its therapeutic action on heart damage. A significant difference in body-weight increase and survival was observed between the treatment groups: ADR-529 injected prior to the first DXR dose significantly protected animals from DXR toxicity, but this schedule was significantly more toxic than the administration of ADR-529 beginning with the third or sixth DXR dose. Taking into account the degree of cardiac protection and the toxicity of combination treatments, the results of the present study demonstrate the superiority of ADR-529 given prior to the third DXR dose over the other schedules tested. This finding suggests that significant protection against DXR-induced chronic cardiotoxicity in the rat can be obtained using deferred treatment with ADR-529.

The protective activity of ICRF-187 against doxorubicin-induced cardiotoxicity in the rat

The protective activity of the bisdioxopiperazine ICRF-187 against the cardiotoxicity of doxorubicin was evaluated in the rat using both functional and histological assays. Animals that had received a single i.v. dose of doxorubicin (4 mg/kg) alone were compared with those that had been pretreated with a single i.v. injection of saline or ICRF-187 (40 or 60 mg/kg). All rats showed a transient reduction in body weight during the first 3 weeks after drug administration. The greatest reduction (approximately 16%) was observed in animals that had received a combination of ICRF-187 (40 or 60 mg/kg) and doxorubicin. Deaths related to cardiotoxicity were observed only in rats that had received doxorubicin alone and in those treated with saline; most of the deaths occurred at between 8 and 13 weeks after drug administration. Sequential assessments of heart function showed a persistent depression of cardiac output in animals that had received doxorubicin, with or without pretreatment with ICRF-187. The reduction in cardiac output observed in rats that had been pretreated with ICRF-187 (40 or 60 mg/kg) amounted to approximately 15% and approximately 30% after 12 and 20 weeks, respectively, indicating that cardioprotection was only partial. Nevertheless, this represented a marked improvement as compared with the approximately 35% reduction in cardiac output measured at 12 weeks in animals that had received doxorubicin but without pretreatment with ICRF-187. Histological examination of animals that had died during the course of the study and had received doxorubicin after pretreatment with saline revealed severe myocardial lesions typical of doxorubicin-induced damage. In contrast, animals that had been pretreated with ICRF-187 and survived for up to 20 weeks after treatment showed a marked amelioration of these lesions. The present findings may be interpreted as a true cardioprotection or a delay in the onset of the cardiotoxicity of doxorubicin resulting from pretreatment with the bisdioxopiperazine ICRF-187. Although prior and ongoing clinical trials clearly indicate that ICRF-187 protects patients well against doxorubicin-induced heart damage, further investigations are required before high doses of ICRF-187 can be used as a means of increasing the protective activity of this drug against doxorubicin-induced cardiotoxicity.

Systemic therapy of advanced breast cancer

Many cytotoxic agents have demonstrated activity in advanced breast cancer, the more active agents being cyclophosphamide and the anthracyclines doxorubicin and epirubicin. Combinations of drugs are generally superior to single agents in terms of response rate, duration of response and survival. The treatment of advanced breast cancer can be continued either until treatment failure, or for a limited time from either initiation of therapy or from the observation of complete response. Although these are issues of significant concern, data from randomised trials are limited, and so the question of optimal treatment duration remains open. Randomised trials comparing regimens that differ by a dose intensity factor of less than 2 have failed to demonstrate significant differences in efficacy between the dose levels. With higher doses, as applied in combination with colony-stimulating factors and bone marrow transplantation, response rates seem to increase, but whether this translates into improved survival has not yet been answered by the results of randomised trials. Approximately 30% of patients respond to endocrine therapy. From the results of randomised trials, which have compared the efficacies and toxicities of different endocrine modalities including combined endocrine therapy, single-agent tamoxifen is generally considered as the preferred first-line treatment, leaving progestins and aromatase inhibitors as alternatives for second-line endocrine therapy in responders. In the majority of trials, chemotherapy combined with endocrine therapy has given improved response rates compared with chemotherapy alone, but the differences have not generally been translated into prolonged survival with combined modalities. This gives rise to the question of the optimal sequence of chemotherapy and endocrine therapy, a subject needing further evaluation in future trials.

Influence of the cardioprotective agent dexrazoxane on doxorubicin pharmacokinetics in the dog

The influence of dexrazoxane on doxorubicin pharmacokinetics was investigated in four dogs using the two treatment sequences of saline/doxorubicin or dexrazoxane/doxorubicin. Intravenous doses of 1.5 mg/kg doxorubicin and 30 mg/kg (the 20-fold multiple) dexrazoxane were given separately, with doxorubicin being injected within 1 min of the dexrazoxane dose. Both doxorubicin and its 13-dihydro metabolite doxorubicinol were quantified in plasma and urine using a validated high-performance liquid chromatographic (HPLC) fluorescence assay. The doxorubicin plasma concentration versus time data were adequately fit by a three-compartment model. The mean half-lives calculated for the fast and slow distributive and terminal elimination phases in the saline/doxorubicin group were 3.0 +/- 0.5 and 32.2 +/- 12.8 min and 30.0 +/- 4.0 h, respectively. The model-predicted plasma concentrations were virtually identical for the saline and dexrazoxane treatment groups. Analysis of variance of the area under the plasma concentration-time curve (AUCo-infinity), terminal elimination rate (lambda z), systemic clearance (CLs), and renal clearance (CLr) for the parent drug showed no statistically significant difference (P greater than 0.05) between the two treatments. Furthermore, the doxorubicinol plasma AUCo-t value and the doxorubicinol-to-doxorubicin AUCo-t ratio showed no significant difference, demonstrating that dexrazoxane had no effect on the metabolic capacity for formation of the 13-dihydro metabolite. The total urinary excretion measured as parent drug plus doxorubicinol and the metabolite-to-parent ratio in urine were also unaffected by the presence of dexrazoxane. The myelosuppressive effects of doxorubicin as determined by WBC monitoring revealed no apparent difference between the two treatments. In conclusion, these results show that drug exposure was similar for the two treatment arms. No kinetic interaction with dexrazoxane suggests that its coadministration is unlikely to modify the safety and/or efficacy of doxorubicin.

Long-term effects of adjuvant chemotherapy in breast cancer

Late effects of adjuvant chemotherapy (ACT) may include second malignant neoplasms (SMN), cardiotoxicity and ovarian suppression. Effects on the biology of residual tumour may be important in protocol design. Studies of SMN need large and reliable data sets. The leukaemia risk with current ACT is likely to be less than a five-fold increase. Leukaemia is predominantly a result of alkylating agents and peaks before 10 years. Solid SMN result also from radiotherapy and this risk continues after 10 years. Cardiotoxicity can be caused by anthracyclines but should not be a problem with current ACT regimens. It can be reduced by careful monitoring and by the cardioprotector ICRF-187. Amenorrhoea is a crude marker of ovarian suppression which may explain conflicting data on its relationship to outcome after ACT. Ovarian suppression following ACT is more likely and more permanent in older premenopausal women, but only explains a part of the ACT effects on outcome. Effects of early ACT on residual tumour are important for planning retreatments and combined modality protocols.

Phase II trial of ICRF-187 in children with solid tumors and acute leukemia

ICRF-187 is the (+) enantiomer of the racemic mixture razoxane (ICRF-159). This compound is much more water soluble and thus could be formulated for parental use. The maximum tolerated dose in children after phase I trials was determined to be 3500 mg/M2/day x 3 days. A phase II trial of ICRF-187 was done in 21 children with solid tumors and 35 children with acute leukemia. All these patients were less than 21 years of age, had recovered from previous chemotherapy, had normal liver and kidney functions, and had a life expectancy of greater than 4 weeks. ICRF-187 was administered at a dose of 3 g/M2/day for 3 days as a 4 hour infusion each day. In patients with leukemia, no objective response was seen in the bone marrow although a few patients had a decrease in peripheral blast count. There were no measurable responses seen in patients with a solid tumor. ICRF-187 was well tolerated. The major toxicity was hematopoietic depression. Significant but rare toxicities included moderate to severe nausea and vomiting, and elevation of bilirubin and transaminases. Although inactive in the current study, ICRF-187 might be more active in another schedule.

Drug antioxidant effects. A basis for drug selection?

A free radical is any species capable of independent existence that contains one or more unpaired electrons. Free radical reactions have been implicated in the pathology of more than 50 human diseases. Radicals and other reactive oxygen species are formed constantly in the human body, both by deliberate synthesis (e.g. by activated phagocytes) and by chemical side-reactions. They are removed by enzymic and nonenzymic antioxidant defence systems. Oxidative stress, occurring when antioxidant defences are inadequate, can damage lipids, proteins, carbohydrates and DNA. A few clinical conditions are caused by oxidative stress, but more often the stress results from the disease. Sometimes it then makes a significant contribution to the disease pathology, and sometimes it does not. Several antioxidants are available for therapeutic use. They include molecules naturally present in the body [superoxide dismutase (SOD), alpha-tocopherol, glutathione and its precursors, ascorbic acid, adenosine, lactoferrin and carotenoids] as well as synthetic antioxidants [such as thiols, ebselen (PZ51), xanthine oxidase inhibitors, inhibitors of phagocyte function, iron ion chelators and probucol]. The therapeutic efficacy of SOD, alpha-tocopherol and ascorbic acid in the treatment of human disease is generally unimpressive to date although dietary deficiencies of the last two molecules should certainly be avoided. Xanthine oxidase inhibitors may be of limited relevance as antioxidants for human use. Exciting preliminary results with probucol (antiatherosclerosis), ebselen (anti-inflammatory), and iron ion chelators (in thalassaemia, leukaemia, malaria, stroke, traumatic brain injury and haemorrhagic shock) need to be confirmed by controlled clinical trials. Clinical testing of N-acetylcysteine in HIV-1-positive subjects may also be merited. A few drugs already in clinical use may have some antioxidant properties, but this ability is not widespread and drug-derived radicals may occasionally cause significant damage.

Interaction between cytostatics and nutrients

Cancer patients have the highest prevalence of malnutrition of any group of hospitalized patients. The presence of the tumor alone may lead to reduced intake of different nutrients and treatment modalities such as surgery, chemotherapy and radiation therapy may further exacerbate nutritional disturbances. Dietary manipulation in experimental systems has shown improvement of tumor response to cancer therapy. Drug pharmacokinetics has been shown to be altered by changes in nutritional delivery. This article reviews the present knowledge, from experimental and clinical standpoints, of the potential role of different nutritional factors on the specific cancer treatment. It is obvious that alteration of at least some dietary factors affect the outcome of different forms of cancer treatment. Indeed, although interest in the clinical significance of optimal dietary intake and supplementation during cancer therapy so far remain marginal, accumulating data indicate that this area deserves further research attention.

Characterization of the aqueous decomposition products of (+)1,2-bis(3,5-dioxopiperazinyl-1-yl)-propane (ICRF-187) by liquid chromatographic and mass spectral analysis

High-performance liquid chromatography (HPLC) and fast atom bombardment mass spectrometry (FAB-MS) were employed to separate and identify the aqueous decomposition products of (+)1,2-bis(3,5-dioxopiperazinyl-1-yl)-propane (ICRF-187; 1), a drug active against several forms of human cancer and which also has recently been shown to display potent cardioprotective activity in patients treated with the antitumor antibiotic doxorubicin. Two reversed-phase HPLC columns were used to separate the hydrolysis products of 1, a Waters muBondapak phenyl column and an LKB Spherisorb ODS2 column. Incubation of 20 microM 1 in phosphate-buffered saline (PBS) at 37 degrees C for 21 h resulted in 47% decomposition, with three hydrolysis products detected (compound 2, Waters column retention time (RT) = 3.7 min, observed monoisotopic protonated molecular ion (MH+) m/z value of 305.1; compound 3, RT = 4.1 min, MH+ m/z value of 287.1; compound 4, RT = 4.8 min, MH+ m/z value of 287.1). The RT and MH+ m/z values for 1 were 17.1 min and 269.1, respectively. Based on the FAB-MS data, 2 corresponds to ICRF-198, the polar diacid diamide derivative of 1, while peaks 3 and 4 represent the monoacid monoamide derivatives of 1. Using B/E linked scan daughter FAB-MS analysis, 3 displayed a prominent fragment with a m/z value of 160, indicating that it corresponds to the monoacid monoamide derivative of 1, with the methyl group adjacent to the hydrolyzed ring. Compound 4, displaying a fragment with a m/z value of 142 in its B/E linked scan daughter ion spectrum, corresponds to the monoacid monoamide derivative of 1, with the methyl group adjacent to the closed ring.

Principles of treatment of pediatric solid tumors

Great strides have been made in the treatment of pediatric solid tumors over the last three decades. A multimodality approach involving a combination of surgery, radiation therapy, and chemotherapy is now used in the treatment of these diseases. This article reviews the principles that guide the use of these modalities and the multidisciplinary approach used to integrate them into a coordinated treatment plan. The role of each modality in the control of local and systemic disease is described. Radiation treatment planning, dose fractionation, and toxicity are also discussed.

New anthracycline antitumor antibiotics

Doxorubicin is an essential component of the treatment of aggressive lymphoma, childhood solid tumors, bone and soft tissue sarcomas, and breast cancer and additional indications are emerging. On the other hand, daunorubicin has occupied the central position of interest in the treatment of acute leukemia. Epirubicin has a spectrum very similar to doxorubicin but lesser toxicity. The ability to protect against cardiotoxicity with ICRF-187 further enhances clinical interest in exploiting modifications in doze intensity to therapeutic advantage. Idarubicin has at least equivalent activity to daunorubicin and doxorubicin in leukemia. New areas of research in relation to anthracycline antibiotics include introduction of new the analogs, insight into mechanisms of resistance, the reversal of multidrug resistance in vitro, the protection of cardiac toxicity, and the study of other important biochemical reactions relevant to cytotoxicity. Orally active anthracyclines such as idarubicin and compounds which lack cross-resistance with the parent drugs or have other mechanisms for cytotoxicity are being developed. It is likely that these modifications will lead to an expanding therapeutic spectrum for these already widely useful drugs.

The iron(III) and copper(II) complexes of adriamycin promote the hydrolysis of the cardioprotective agent ICRF-187 ((+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane)

ICRF-187 ((+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane) has shown promise (Speyer et al., N. Engl. J. Med. 319, 745 (1988] as a cardioprotective agent against what may be an iron-based adriamycin-induced cardiotoxicity. ICRF-187, which is membrane permeable, likely exerts its action through its rings-opened hydrolysis product which has a structure similar to EDTA and which, likewise, strongly binds metal ions. Both Fe3(+)-adriamycin and Cu2(+)-adriamycin reacted directly with ICRF-187, promoting a ring-opening hydrolysis of ICRF-187 that resulted in the displacement of the metal ion from its complex with adriamycin. Thus ICRF-187 can be considered to be acting as a "suicide protective agent" in its reaction with metal ion-adriamycin complexes. That this metal ion complex-promoted hydrolysis was preceded by mixed ligand complex formation is evidenced by the fact that the first-order rate constant for loss of metal ion from the adriamycin complex exhibits saturation behaviour at high ICRF-187 concentrations. Also direct spectroscopic evidence was obtained both for a Cu2(+)-adriamycin-ICRF-187 mixed ligand complex and a Cu2+ (ICRF-187)2 complex. The Fe3(+)-adriamycin complex inactivates the cytochrome c oxidase and NADH cytochrome c reductase activity on submitochondrial particles. The protection that ICRF-187 affords against this loss of activity may be explained both on the basis of simple Fe3+ removal from Fe3(+)-adriamycin and also on formation of a less active Fe3(+)-adriamycin-ICRF-187 mixed ligand complex.

Inhibition and inactivation of NADH-cytochrome c reductase activity of bovine heart submitochondrial particles by the iron(III)-adriamycin complex

The NADH-cytochrome c reductase activity of bovine heart submitochondrial particles was found to be slowly (half-time of 16 min) and progressively lost upon incubation with the Fe2(+)-adriamycin complex. In addition to this slow progressive inactivation seen on incubation, a reversible fast phase of inhibition was also seen. However, if EDTA was added to the incubation mixture within 15 s, the slow progressive loss in activity was largely preventable. Separate experiments indicated that EDTA removed about one-half of the iron from the Fe2(+)-adriamycin complex in about 40 s. These results indicated the requirement for iron for the inactivation process. Since the Vmax. for the fast phase of inhibition was decreased by the inhibitor, the inhibition pattern was similar to that seen for uncompetitive or mixed-type inhibition. The direct binding of both Fe3(+)-adriamycin and adriamycin to submitochondrial particles was also demonstrated, with the Fe3(+)-adriamycin complex binding 8 times more strongly than adriamycin. Thus binding of Fe3(+)-adriamycin to the enzyme or to the inner mitochondrial membrane with subsequent generation of oxy radicals in situ is a possible mechanism for the Fe3(+)-adriamycin-induced inactivation of respiratory enzyme activity.

Evidence of the selective alteration of anthracycline activity due to modulation by ICRF-187 (ADR-529)

Anthracyclines are powerful anticancer drugs whose use is limited by the development of chronic cardiotoxicity. The bisdioxopiperazine compound ICRF-187 (ADR-529) specifically abrogates this toxicity both in preclinical animal models and in humans. It does this without effecting either the acute toxicities or the anticancer activity. Therefore, with a specific antagonist, the mechanism of activity of the anthracyclines can be explored. This review discusses recent clinical trials and animal models addressing this issue and concludes by hypothesizing a mechanism of action.

Role of the glutathione-glutathione peroxidase cycle in the cytotoxicity of the anticancer quinones

Recent studies have suggested that the selenoenzyme glutathione peroxidase, in the presence of reducing equivalents from the tripeptide glutathione, is responsible for detoxifying hydrogen peroxide and lipid hydroperoxides generated as a consequence of the cyclic reduction and oxidation of quinone-containing anticancer agents including doxorubicin, daunorubicin, mitomycin C, diaziquone, and menadione. Alterations in the intracellular levels of glutathione peroxidase or glutathione can significantly affect the activity of these drugs against human tumor cells and the expression of their normal tissue toxicity, especially with respect to the heart. Furthermore, augmentation of the glutathione peroxidase pathway appears to render certain human tumor cells relatively resistant to the anticancer quinones; therefore, the glutathione peroxidase system may, at least in part, modulate certain forms of acquired drug resistance in man. Thus, the glutathione peroxidase cycle appears to play a central role in maintaining intracellular peroxide homeostasis during quinone-induced oxidative stress.

ICRF 187 and polyhydroxyphenyl derivatives fail to protect against bleomycin induced lung injury

The potential protective effects of ICRF 187, Didox, Amidox and VF 165 were investigated in models of bleomycin, or bleomycin and hyperoxia induced lung injury. ICRF 187, a bispiperazinedione compound, is a strong chelating agent which blocks a number of free radical mediated processes. The polyhydroxyphenyl derivatives, Didox, Amidox and VF 165, demonstrate degrees of Fe chelating activities and free radical scavenging abilities. Hamsters treated with 5.0 U/kg bleomycin followed by treatment with ICRF 187 or Didox exhibited similar mortality to the bleomycin alone treated group. In a second study, a low dose of bleomycin (1.2 U/kg) was used followed by exposure to 70% oxygen. Treatment with ICRF 187, Didox, Amidox, or VF 165 failed to protect against lung injury; with the ICRF 187 and Amidox groups exhibiting significantly increased rates of mortality over that seen in animals treated only with bleomycin and hyperoxia. No animals treated with the agents alone died. Histopathology documented that all bleomycin-treated hamsters died of severe pneumonitis. Additionally, in the agent-treated groups there was a prominent proliferation of type II pneumocytes, which demonstrated marked anaplasia, a feature not typical of early bleomycin and hyperoxia lung injury. In conclusion, ICRF 187 and the polyhydroxyphenyl derivative, Amidox, paradoxically increase bleomycin- and hyperoxia-induced lung injury. The possible mechanisms of this interaction include: (1) increased availability of Fe to bleomycin; (2) interference with the healing process; or (3) inhibition of endogenous protective effects of SOD.

Pathologic anatomy of the dilated cardiomyopathies

Dilated cardiomyopathies are characterized by systolic pump failure and by dilatation of the ventricular cavity. Thus, they differ from the other 2 main types of cardiomyopathies, namely, hypertrophic cardiomyopathy and restrictive/obliterative cardiomyopathy. The term dilated cardiomyopathy designates a number of heterogeneous syndromes: idiopathic dilated cardiomyopathy, alcoholic cardiomyopathy, postpartal cardiomyopathy, infantile cardiomyopathy with histiocytoid change in cardiac muscle cells, anthracycline cardiomyopathy, Keshan disease, and several ultrastructurally distinct abnormalities, some of which maybe familial. The pathologic features of these syndromes are reviewed in detail.

Doxorubicin: effect of different schedules on toxicity and anti-tumor efficacy

The risk of congestive heart failure restricts the clinical use of doxorubicin to cumulative doses of 450-550 mg/m2, when it is given using high-dose rapid intravenous application. As the high peak serum levels which follow rapid administration seem to be correlated with cardiotoxicity, application schedules leading to lower peak serum concentrations have been developed. This paper reviews the influence of those schedules on cardiotoxicity, non-cardiac toxicities, pharmacokinetic data and antineoplastic efficacy. While the reduction of cardiotoxicity by long-term application schedules is well documented, much less can be said about the antitumor effect of those schedules. Controlled studies dealing with this problem are needed. This review provides a base for that purpose.

The Adriamycin (doxorubicin)-induced inactivation of cytochrome c oxidase depends on the presence of iron or copper

1. It was confirmed that Adriamycin (doxorubicin) inactivates cytochrome c oxidase upon incubation. However, further investigation shows that this inactivation is strongly dependent upon the presence of Fe3+ and Cu2+. Trace amounts of these transition metal ions, present in phosphate and Tris buffers, bind strongly to the Adriamycin and the complex formed is responsible for the inactivation of cytochrome c oxidase. No Adriamycin-induced inactivation of cytochrome c oxidase occurred in the presence of EDTA or in phosphate buffers purified on a cation exchange column to remove trace metals. 2. The metal ion-induced inactivation of cytochrome c oxidase by Adriamycin results in significant decreases in both the maximum velocity and the Michaelis constant. The degree of inactivation is strongly dependent on the Fe3+ concentration. 3. Cardiolipin partially protects against cytochrome c oxidase inactivation, presumably by binding to the cytochrome c oxidase, whereas catalase or superoxide dismutase partially protect by scavenging damaging reactive oxygen species generated within a Fe3+-Adriamycin-enzyme complex.

Self-reduction of the iron(III)-doxorubicin complex

The Fe3(+)-doxorubicin complex undergoes reactions that suggest that the complex self-reduces to a ferrous oxidized-doxorubicin free radical species. The Fe3(+)-doxorubicin system is observed to reduce ferricytochrome c, consume O2 and react with 2,2'-bipyridine. Bipyridine acts as a "ferrous ion scavenger" as it reacts with the ferrous ion produced by Fe3(+)-doxorubicin self-reduction. In the absence of O2, a ferrous doxorubicin complex accumulates. In the presence of oxygen, Fe2+ recycles back to Fe3+. The rates of these reactions were measured and the Fe3(+)-doxorubicin self-reduction was determined to be the rate-determining step. The Fe3(+)-doxorubicin induced inactivation of cytochrome c oxidase and NADH cytochrome c reductase on beef heart submitochondrial particles occurs at a rate similar to Fe3(+)-doxorubicin self-reduction. Thus the rate at which damage to these mitochondrial enzymes occurs may be controlled by a nonenzymatic Fe3(+)-doxorubicin self-reduction.

Cardiac damage in autologous bone marrow transplant patients: an autopsy study. Cardiotoxic pretreatment as a major risk factor

The myocardium was studied histologically at autopsy in seven patients who died 9-85 days (median 22 days) after autologous bone marrow or blood-derived stem-cell transplantation. Clinical investigations including echocardiography suggested normal cardiac function in all patients prior to transplantation. Myeloablation was performed by total body irradiation (1200-1560 cGy) and cyclophosphamide (200 mg/kg). Morphological findings were graded semi-quantitatively and correlated with previous and current therapy. Histological alterations did not correspond to the dosages of myeloablative therapy. However, cardiac failure, the primary cause of death in four patients, was associated with coagulative fiber necroses and contraction band necroses, which may be related to acute cyclophosphamide toxicity. In three of these patients high-dose cardiotoxic pretreatment with anthracyclines and mitoxantrone has been performed beyond the critical cardiotoxic level. High-dose pretreatment was correlated with histological hallmarks of anthracycline heart disease: marked chromatin clumping of myocardial cell nuclei (3/3 patients), occurrence of plurivesicular "adria" cells (3/3 patients), and diffuse interstitial myocardial fibrosis (2/3 patients). Our morphological observations indicate for the first time that pretreatment with anthracyclines and mitoxantrone may enhance cardiotoxicity of myeloablative therapy in bone marrow transplantation.