Comparison of the protective effects of desferrioxamine and ICRF-187 against doxorubicin-induced toxicity in spontaneously hypertensive rats

Since the iron-mediated formation of free radicals is considered to be a critical factor in the pathogenesis of the toxicity of doxorubicin (DXR), comparisons were made of the protective effects of two iron chelators, ICRF-187 and desferrioxamine (DFO), against the chronic cardiac and renal toxicity induced by DXR in spontaneously hypertensive rats (SHR). Two preparations of DFO were studied: DFO mesylate (DFO-M) and a polymeric form (DFO-P) in which DFO is conjugated to hydroxyethyl starch. Groups of 5 SHR each were given 12 weekly i.v. injections of 1 mg/kg DXR either alone or 30 min after the i.p. injection of 25 mg/kg ICRF-187, 50 mg/kg DFO-M, 50 mg/kg DFO-P, or 100 mg/kg DFO-P. A semiquantitative assessment was made of the cardiomyopathy (Billingham scale) and nephropathy. Renal protection was minimal with DFO-M and moderate with ICRF-187 and both doses of DFO-P. There was no cardiac protection with DFO-M. Both doses of DFO-P provided similar but modest degrees of cardiac protection. DXR-induced mortality was not prevented by either preparation of DFO. ICRF-187 provided a higher degree of protection against the cardiotoxicity and the mortality induced by DXR. Since both DFO and ICRF-187 are highly efficient chelators of iron in vitro, the differences in their in vivo protective effects are thought to be related to their cellular uptake and intracellular distribution and to the relative availability of different intracellular iron pools to these agents.     

Modification of doxorubicin-induced cardiotoxicity: effect of essential fatty acids and ICRF-187 (dexrazoxane)

The capacity of an oil, containing gamma-linolenic acid (GLA), to reduce the severity of doxorubicin-induced cardiotoxicity has been investigated in a rat model. Groups of 12-week-old, male, Sprague–Dawley rats were injected intravenously (i.v.) with single doses (3 mg/kg body weight) of doxorubicin (DOX). Daily for 1 week prior to DOX administration and for up to 20 weeks afterwards groups of rats received either an oil containing both GLA and linoleic acid (So-1100, Scotia Pharmaceuticals), at two dose levels, or an oil containing linoleic acid, but no GLA (So-1129) by oral gavage. Other groups of rats received water as a control. One of the groups of rats that received water also received i.v. ICRF-187 (60 mg/kg) 15 min prior to DOX. A group of animals acted as age-matched controls. The maximum reduction in body weight in the first 2 weeks after the administration of DOX. was used as a measure of acute toxicity. This was most severe in the group receiving a combination of DOX and ICRF-187 (5.6±0.43%). Animals receiving 2 ml of either So-1100 or So-1129 were the least affected (≈2.5%). Measurements of cardiac volume output made at various intervals after DOX administration indicated a ≈35% reduction in cardiac function in the control and So-1129 oil group after 20 weeks. The corresponding reduction in the groups receiving ICRF-187 and 2 ml of So-1100 was ≈16%. The group receiving daily doses of 1 ml So-1100 showed an intermediate response. The death of an animal with signs of congestive cardiac failure occurred in 40% of the animals in the DOX only control (water) group. There were no deaths in the groups of rats receiving either ICRF-187 or pre- and post-administration of 2 ml of So-1100. It was concluded that an oil containing GLA (So-1100) has similar cardioprotective properties against DOX-induced cardiotoxicity as ICRF-187, but with less general toxicity in this rat model.     

Pretreatment with ICRF-187 provides long-lasting protection against chronic daunorubicin cardiotoxicity in rabbits

Summary The long-term protective effect of ICRF-187 against chronic daunorubicin cardiotoxicity was examined. Rabbits were given 3.2 mg daunorubicin/kg, with or without pretreatment with 25 mg ICRF-187/kg, once every 3 weeks over an 18-week period (6 doses). The experiment was terminated 3 months after the last treatment. At this time, all seven rabbits given daunorubicin alone had evidence of myocardial alterations ranging from minimal (2 animals) to mild (5 animals). Pretreatment with ICRF-187 caused a significant reduction in both the incidence and the severity of cardiac lesions. Hearts from the majority (5 of 7) of animals given the combination of ICRF-187 and daunorubicin were normal; myocardial alterations were minimal in the remaining rabbits treated with ICRF-187. In previous studies ICRF-187 was found to cause a reduction in cardiotoxicity 1–3 weeks after the final anthracycline dose. The results of the present study demonstrate that pretreatment with ICRF-187 provides prolonged protection against the cardiomyopathy, as opposed to producing only a delay in the appearance of cardiac alterations.     

Comparison of the protective effects against chronic doxorubicin cardiotoxicity and the rates of iron (III) displacement reactions of ICRF-187 and other bisdiketopiperazines

Histologic and biochemical studies were carried out to compare the protective activity of various bisdiketopiperazines against the cardiac and renal toxicity induced by doxorubicin in spontaneously hypertensive rats (SHR), a well-established animal model of this disorder, with: (1) the rates of hydrolysis of these agents to form the iron-chelating derivatives (which are considered to cause a decrease in the formation of reactive oxygen intermediates) and (2) the ability of these derivatives to bind iron. SHR were given 12 weekly injections of doxorubicin, 1 mg/kg i.v. either alone or 30 min after the administration of ICRF-154, ICRF-187, ICRF-192, ICRF-197, ICRF-198, ICRF-239 and ADR-559. Semiquantitative grading of the severity of the resulting cardiac and renal lesions showed that ICRF-187, ICRF-154 and ADR-559 were the most protective, whereas ICRF-197 and ICRF-239 provided intermediate degrees of protection, and ICRF-192 and ICRF-198 were not protective. Quantitative measurements in vitro revealed only relatively small differences in the rates of opening of the two diketopiperazine rings of the various agents to form the corresponding iron-chelating diacid diamide derivatives, and in the ability of these various derivatives to remove iron from the iron–doxorubicin complex. Such differences showed no relationship with cardioprotective activity. Some bisdiketopiperazines (including ICRF-154 and ICRF-187) with cardioprotective activity also are inhibitors of DNA topoisomerase II; however, the significance of this relationship remains uncertain, since ADR-925, the open-ring derivative of ICRF-187, does not inhibit DNA topoisomerase II. Received: 8 May 1996 / Accepted: 14 January 1997     

Effect of ICRF-187 on doxorubicin-induced myocardial effects in the mouse and guinea pig.

ICRF-187 was tested for cardioprotective activity in doxorubicin-treated mice and guinea pigs. Pretreatment with i.p. ICRF-187 caused a significant decrease in the indicence of i.v. doxorubicin-induced myocardial histological damage in the mouse. I.p. ICRF-187 did not, however, reduce the effect of i.p. doxorubicin on a functional myocardial effect of this antitumour drug, a reduced histamine responsiveness of right atria in vitro. These data suggest that ICRF-187 may not be specific for all the cardiac effects of doxorubicin.     

Timing of treatment with ICRF-187 and its effect on chronic doxorubicin cardiotoxicity

Studies were conducted to evaluate whether the timing of administration of ICRF-187 [(+)-1,2-bis(3,5 dioxopiperazinyl-1-yl)propane] would influence the degree of cardioprotection provided by this agent against the development of doxorubicin-induced chronic cardiomyopathy. Beagle dogs (8.5–14 kg) received either doxorubicin alone (1.75 mg/kg, i. v.,n=8), doxorubicin (1.75 mg/kg) simultaneously with ICRF-187 (35 mg/kg, i. v.,n=8), or doxorubicin (1.75 mg/kg) followed 2 h later by ICRF-187 (35 mg/kg,n=8). Control animals received ICRF-187 (35 mg/kg,n=4) or saline (n=4). All animals received a course of seven treatments, each given 3 weeks apart, and were killed 3 weeks after the last treatment. Semiquantitative grading of histologic sections of myocardium showed that as compared with animals treated with doxorubicin alone, the incidence and the severity of the doxorubicin-induced myocardial lesions were reduced in the two groups of animals given doxorubicin plus ICRF-187. However, protection was significantly better in dogs receiving ICRF-187 and doxorubicin simultaneously than in those given ICRF-187 2 h after doxorubicin. These observations were interpreted as indicating that the timing of administration of ICRF-187 with respect to that of doxorubicin is an important factor in determining the degree of cardioprotection and that there is a time window in which ICRF-187 exerts optimal effects.     

New aspects in probucol cardioprotection against doxorubicin-induced cardiotoxicity

Purpose Doxorubicin (DOX) is a broad-spectrum anticancer drug with dose-dependent cardiotoxicity. Probucol has been reported to completely prevent DOX-induced cardiomyopathy. The aim of the present study was to determine the possible effect of probucol pretreatment on the pharmacokinetics of DOX and its role in cardioprotection as well as the possible contribution of the lipid-lowering effect of probucol on the disposition of DOX in cardiac tissue.Methods Two groups of male albino rats were given either probucol (10 mg/kg, i.p.) or corn oil daily for 12 days followed by a single dose of DOX (15 mg/kg, i.p.). The concentration-time profile of DOX in plasma and its concentration in different tissues, and plasma and myocardial lipids were determined.Results A rapid and significant increase in plasma DOX clearance was observed in rats pretreated with probucol. Probucol induced a significant increase in DOX concentration in both liver and kidney tissues and a significant decrease in DOX concentration in the spleen. However, heart and lung DOX concentrations were not affected. Also, probucol pretreatment resulted in a significant reduction in cardiotoxicity indices including peak serum creatine kinase (CK) concentration and the area under the CK concentration-time curve. Moreover, probucol pretreatment not only counteracted significantly the decrease in the ATP/ADP ratio induced by DOX, but also induced a significant increase as compared with the control group. In addition, probucol significantly reduced plasma total cholesterol and low-density lipoprotein, but it did not induce any significant changes in myocardial lipids.Conclusions The present study demonstrated, for the first time, that probucol pretreatment alters the pharmacokinetics of DOX. Besides its antioxidant properties, the cardioprotective effect of probucol may be related to its enhancing action on the ATP/ADP ratio.     

Cardioprotective effects of dapsone against doxorubicin-induced cardiotoxicity in rats

Cancer Chemotherapy and Pharmacology - It has been supposed that cardiac toxicity of doxorubicin is due to its production of free radicals and inflammatory cytokines. Dapsone, an antibiotic drug...     

The protective effect of cardiac gene transfer of CuZn-sod in comparison with the cardioprotector monohydroxyethylrutoside against doxorubicin-induced cardiotoxicity in cultured cells

Doxorubicin-induced cardiotoxicity is related to its production of free radicals that specifically affect heart tissue because of its low antioxidant status. Monohydroxyethylrutoside (monoHER), a potent antioxidant flavonoid, is under development as a protector against doxorubicin-induced cardiotoxicity. The overexpression of high levels of superoxide dismutase (sod) protects against free radical damage in transgenic mice. Seeking alternatives besides the few cardioprotectors that are presently under investigation, the aim of the present study was to investigate the protective effect of cardiac gene transfer of CuZn-sod compared with that of the presently most promising cardioprotector monoHER against doxorubicin-induced cardiotoxic effects on neonatal rat cardiac myocytes (NeRCaMs) in vitro. NeRCaMs were infected with different multiplicity of infections (MOIs) of adenovirus encoding CuZn-sod (AdCuZn-sod). A control infection with an adenovirus vector encoding a nonrelated protein was included. The overexpression of CuZn-sod was characterized within 3 days postinfection. For doxorubicin treatment, NeRCaMs were divided into three groups. The first group was infected with AdCuZn-sod before treatment with doxorubicin (0-50 microM). The second and third groups were treated with doxorubicin (0-50 microM) alone and with 1 mM monoHER, respectively. The LDH release and survival of treated cells were measured 24 and 48 hours after doxorubicin treatment. The beating rate was followed during the 3 days after doxorubicin (0-100 microM) treatment. At the third day after infection with an MOI of 25 plaque-forming unit (PFU) of AdCuZn-sod/cell, the activity of CuZn-sod significantly increased (five-fold, P=.029). Higher MOI produced cytopathic effects (CPEs). Doxorubicin alone produced significant concentration- and time-dependent reduction in NeRCaMs beating rate and survival (P < .0005). Doxorubicin (> or =50 microM)-treated cells ceased to beat after 24 hours. This cytotoxicity was associated with an increase in the LDH release from the treated cells (P <.0005).The five-fold increase in the activity of CuZn-sod did not protect against any of the cytotoxic effects of doxorubicin on NeRCaMs. In contrast, monoHER (1 mM) protected against the lethal effects of doxorubicin on the survival, LDH release and the beating rate of NeRCaMs (P <.004) during 48 hours after doxorubicin treatment. Doxorubicin-treated (< or =100 microM) cells continued beating for >72 hours in the presence of monoHER.The present study showed the lack of adenoviral CuZn-sod gene-transfer to protect myocardiocytes against doxorubicin-induced toxicity and confirms the efficacy of monoHER cardioprotection. Thus, a gene-therapy strategy involving overexpression of CuZn-sod to protect against doxorubicin-induced cardiotoxicity is not feasible with the currently available adenovirus vectors.     

Protection against doxorubicin-induced cardiotoxicity in weanling rats by dexrazoxane

Purpose: Dexrazoxane (DZR) protects against anthracycline-induced cardiotoxicity in several laboratory animal species and in patients with breast cancer. Encouraging results have also been obtained in a limited number of pediatric oncology patients. We conducted studies to determine the safety and cardioprotective activity of DZR in the doxorubicin (DOX)-treated weanling rat simulating the rapidly growing immature child. Methods: Male weanling rats and young adult rats, 20␣days old and 7 weeks old, respectively, were given 1 mg/kg DOX i.v., either alone or with 20 mg/kg DZR, once weekly for 7 weeks. Rats were sacrificed at weeks 8, 12 or 26 following blood collection for hematology and serum chemistry. Hearts were weighed and examined histologically. Results: DOX, either alone or with DZR, inhibited growth, and body weight remained below that of controls throughout the 26 weeks of study. There were no biologically significant hematologic changes in either the DOX- or DZR + DOX-treated young rats. DOX caused a slight increase in liver and kidney weights relative to body weight and a slight increase in serum cholesterol and triglycerides in the young rats. These effects were ameliorated or delayed by DZR. DOX, either alone or with DZR, caused a marked atrophy of the testes in the young rats which had recovered by week 26. In the mature rats, DOX caused a significant decrease in the WBC 1 week after the last treatment, and the WBC was significantly lower in the rats given DZR + DOX compared to those given DOX alone. There were marked increases in liver and kidney weight, serum cholesterol and triglycerides in the mature rats given DOX alone but not in those given DZR + DOX. There was also a marked testicular atrophy in the mature rats given either DOX or DZR + DOX but, unlike that observed in the young rats, this had not returned to normal by week 26. DOX-induced cardiotoxicity was less severe in the younger rats than in the mature rats but in both age groups, the lesion progressed rapidly until week 12, 5 weeks after the last dose, and remained relatively stable or progressed slightly thereafter. DZR provided significant cardioprotection in both age groups at all time points examined. Moreover, in both age groups, the severity of the cardiomyopathy in the DZR-treated rats was somewhat less at week 26 than it was at week 12. Conclusions: The results indicate that the pharmacologic effects of DZR, including its ability to protect against cardiotoxicity, are similar in immature and adult male animals treated with DOX. Received: 3 March 1998 / Accepted: 13 May 1998     

氧化苦参碱对阿霉素心脏毒性的影响

目的：观察氧化苦参碱（oxymatrine，OMT）在动物实验中对阿霉素（ADR）所致心脏毒性的保护作用。方法：26只新西兰大白兔随机分为4组：ADR组（8只）、ADR＋OMT组（8只）、生理盐水组（5只）、OMT组（5只）。实验免每周耳缘静脉注射ADR（2mg／kg）1次，共8周，制备慢性心肌损伤模型。OMT（10mg／kg）于ADR应用前30min经耳缘静脉注射。用药前和停药3周后左颈总动脉及左室插管测定左室射血分数（LVEF）、左心室收缩压（LVSP）和左心室舒张末压（LVEDP）；取血测定血液中乳酸脱氢酶（LDH）和肌酸磷酸激酶（CK—MB）活性。停药3周后，电镜观察心肌细胞超徽结构变化。结果：ADR组中LVEF、LVSP明显降低，LVEDP明显升高，LDH和CK—MB活力显著升高。ADR＋OMT组也有相似改变，程度较轻，两组之间差异有统计学意义。ADR组和ADR＋OMT组均有心肌超微结构损伤，但ADR＋OMT组病变程度明显轻于ADR组。OMT组动物未观察到任何不良反应和病理变化。结论：氧化苦参碱对阿霉素致心肌损伤具有保护作用。     

The role of cardioxane (ICRF-187) in the prevention of cardiotoxicity of anthracyclines in the combined drug therapy of extensive ovarian cancer

The investigation was concerned with clinical application of cardioxane (dexrazoxan, ICRF-187) which is intended to counteract the cardiotoxic effect of anthracycline drugs. It was tested in 24 courses of combination chemotherapy (CAP) in 48 cases of extended ovarian tumor. The "threshold" total dose of doxorubin (500 mg/m2) which caused persistent cardiomyopathy in such patients as well as cases of relapse was practically never reached due to the absence of therapeutic effect. The total dose of doxorubicin of 120 mg/m2 raised the likelihood of acute cardiac intoxication. With prophylactic administration of cardioxane, clinical signs of acute cardiointoxication were slight; irreversible intoxication was recorded in 0.8%. The drug improved tolerance; it neither increased the overall toxicity of combination chemotherapy nor affected the results.     

Anticancer prodrugs of butyric acid and formaldehyde protect against doxorubicin-induced cardiotoxicity

Formaldehyde has been previously shown to play a dominant role in promoting synergy between doxorubicin (Dox) and formaldehyde-releasing butyric acid (BA) prodrugs in killing cancer cells. In this work, we report that these prodrugs also protect neonatal rat cardiomyocytes and adult mice against toxicity elicited by Dox. In cardiomyocytes treated with Dox, the formaldehyde releasing prodrugs butyroyloxymethyl diethylphosphate (AN-7) and butyroyloxymethyl butyrate (AN-1), but not the corresponding acetaldehyde-releasing butyroyloxydiethyl phosphate (AN-88) or butyroyloxyethyl butyrate (AN-11), reduced lactate dehydrogenase leakage, prevented loss of mitochondrial membrane potential (DeltaPsim) and attenuated upregulation of the proapoptotic gene Bax. In Dox-treated mice, AN-7 but not AN-88 attenuated weight-loss and mortality, and increase in serum lactate dehydrogenase. These findings show that BA prodrugs that release formaldehyde and augment Dox anticancer activity also protect against Dox cardiotoxicity. Based on these observations, clinical applications of these prodrugs for patients treated with Dox warrant further investigation.     

Frederine, a new and promising protector against doxorubicin-induced cardiotoxicity.

The flavonoid 7-monohydroxyethylrutoside (monoHER) can protect against doxorubicin-induced cardiotoxicity. A drawback of monoHER therapy would be the relatively high dose needed to obtain complete protection (500 mg/kg in mice). Therefore, we synthesized a series of new compounds with improved antioxidant properties. After characterization of antioxidant activity, cardioprotection in vitro, and possible toxic properties in hepatocytes, we selected Frederine for additional investigations in vivo. In the present study, it was found that this compound did not induce weight loss or (gross) organ changes in mice in a treatment schedule of 170 mg/kg i.p., 5 times/week during 2 weeks. We recorded the electrocardiogram telemetrically in mice during and 2 weeks after the combined treatment with doxorubicin (4 mg/kg, i.v.) and 5 times Frederine (68 mg/kg, i.p.; equimolar to 100 mg/kg monoHER) for 6 weeks. Complete protection against doxorubicin-induced cardiotoxicity was found, indicating that Frederine is at least 5 times more potent than monoHER. Frederine did not have a negative influence on the antiproliferative effects of doxorubicin on A2780, OVCAR-3, and MCF-7 cells in vitro and on OVCAR-3 xenografts grown in nude mice when administered 5 min before doxorubicin (8 mg/kg i.v.) and 4 days thereafter with an interval of 24 h. It can be concluded that we succeeded in designing a better cardioprotector than monoHER. Therefore, Frederine merits further investigation as a possible protector against doxorubicin-induced cardiotoxicity in cancer patients.     

The influence of the time interval between monoHER and doxorubicin administration on the protection against doxorubicin-induced cardiotoxicity in mice

Purpose: Despite its well-known cardiotoxicity, the anthracyclin doxorubicin (DOX) continues to be an effective and widely used chemotherapeutic agent. DOX-induced cardiac damage presumably results from the formation of free radicals by DOX. Reactive oxygen species particularly affect the cardiac myocytes because these cells seem to have a relatively poor antioxidant defense system. The semisynthetic flavonoid monohydroxyethylrutoside (monoHER) showed cardioprotection against DOX-induced cardiotoxicity through its radical scavenging and iron chelating properties. Because of the relatively short final half-life of monoHER (about 30 min), it is expected that the time interval between monoHER and DOX might be of influence on the cardioprotective effect of monoHER. Therefore, the aim of the present study was to investigate this possible effect. Methods: Six groups of 6 BALB/c mice were treated with saline, DOX alone or DOX (4 mg/kg i.v.) preceded by monoHER (500 mg/kg i.p.) with an interval of 10, 30, 60 or 120 min. After a 6-week treatment period and additional observation for 2 weeks, the mice were sacrificed. Their cardiac tissues were processed for light microscopy, after which cardiomyocyte damage was evaluated according to Billingham (in Cancer Treat Rep 62(6):865–872, 1978). Microscopic evaluation revealed that treatment with DOX alone induced significant cardiac damage in comparison to the saline control group (P<0.001). Results: The number of damaged cardiomyocytes was 9.6-fold (95% CI 4.4–21.0) higher in mice treated with DOX alone than that in animals of the control group. The ratio of aberrant cardiomyocytes in mice treated with DOX preceded by monoHER and those in mice treated with saline ranged from 1.6 to 2.8 (mean 2.2, 95% CI 1.2–4.1, P=0.019). The mean protective effect by adding monoHER before DOX led to a significant 4.4-fold reduction (P<0.001, 95% CI 2.3–8.2) of abnormal cardiomyocytes. This protective effect did not depend on the time interval between monoHER and DOX administration (P=0.345). Conclusion: The results indicate that in an outpatient clinical setting monoHER may be administered shortly before DOX.This work was supported in part by grant VU-97-1525 from the Koningin Wilhelmina Foundation, Amsterdam, The Netherlands.