Strategies for prevention of anthracycline cardiotoxicity

Resistance training improves cardiac function and cardiovascular autonomic control in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anticancer chemotherapy drug that is widely used in clinical practice. It is well documented that DOX impairs baroreflex responsiveness and left ventricular function and enhances sympathetic activity, cardiac sympathetic afferent reflexes and oxidative stress, which contribute to hemodynamic deterioration. Because resistance training (RT)-induced cardioprotection has been observed in other animal models, the objective of this study was to assess the effects of RT during DOX treatment on hemodynamics, arterial baroreflex, cardiac autonomic tone, left ventricular function and oxidative stress in rats with DOX-induced cardiotoxicity. Male Wistar rats were submitted to a RT protocol (3 sets of 10 repetitions, 40% of one-repetition maximum (1RM) of intensity, 3 times per week, for 8 weeks). The rats were separated into 3 groups: sedentary control, DOX sedentary (2.5 mg/kg of DOX intraperitoneal injection, once a week, for 6 weeks) and DOX + RT. After training or time control, the animals were anesthetized and 2 catheters were implanted for hemodynamic, arterial baroreflex and cardiac autonomic tone. Another group of animals was used to evaluate left ventricular function. We found that RT in DOX-treated rats decreased diastolic arterial pressure, heart rate, sympathetic tone and oxidative stress. In addition, RT increased arterial baroreflex sensitivity, vagal tone and left ventricular developed pressure in rats with DOX-induced cardiotoxicity. In summary, RT is a useful non-pharmacological strategy to attenuate DOX-induced cardiotoxicity.

N-3 polyunsaturated fatty acids decrease levels of doxorubicin-induced reactive oxygen species in cardiomyocytes -- involvement of uncoupling protein UCP2

BACKGROUND

Use of the chemotherapeutic drug doxorubicin (DOX) is associated with serious cardiotoxicity, as it increases levels of reactive oxygen species (ROS). N-3 polyunsaturated fatty acid dietary supplements can be of benefit to patients undergoing cancer therapy. The aims of this study were to determine whether DOX-induced cardiotoxicity is related to mitochondrial uncoupling proteins and whether eicosapentaenoic acid (EPA, C20:5 n-3) or docosahexaenoic acid (DHA, C22:6 n-3) affects DOX-induced cardiomyocyte toxicity.

RESULTS

Treatment of H9C2 cells with DOX resulted in decreased cell viability and UCP2 expression. Treatment with 100 μM EPA or 50 μM DHA for 24 h resulted in a maximal mitochondria concentration of these fatty acids and increased UCP2 expression. Pretreatment with 100 μM EPA or 50 μM DHA prevented the DOX-induced decrease in UCP2 mRNA and protein levels, but these effects were not seen with EPA or DHA and DOX cotreatment. In addition, the DOX-induced increase in ROS production and subsequent mitochondrial membrane potential change (∆ψ) were significantly attenuated by pretreatment with EPA or DHA.

CONCLUSION

EPA or DHA pre-treatment inhibits the DOX-induced decrease in UCP2 expression, increase in ROS production, and subsequent mitochondrial membrane potential change that contribute to the cardiotoxicity of DOX.

The application of EDTA in drug delivery systems: doxorubicin liposomes loaded via NH4EDTA gradient

The applications of ethylenediaminetetraacetic acid (EDTA) have been expanded from the treatment of heavy metal poisoning to chelation therapies for atherosclerosis, heart disease, and cancers, in which EDTA reduces morbidity and mortality by chelating toxic metal ions. In this study, EDTA was used in a drug delivery system by adopting an NH4EDTA gradient method to load doxorubicin into liposomes with the goal of increasing therapeutic effects and decreasing drug-related cytotoxicity. The particle size of the optimum NH4EDTA gradient liposomes was 79.4±1.87 nm, and the entrapment efficiency was 95.54%±0.59%. In vitro studies revealed that liposomes prepared using an NH4EDTA gradient possessed long-term stability and delayed drug release. The in vivo studies also showed the superiority of the new doxorubicin formulation. Compared with an equivalent drug dose (5 mg/kg) prepared by (NH4)2SO4 gradient, NH4EDTA gradient liposomes showed no significant differences in tumor inhibition ratio, but cardiotoxicity and liposome-related immune organ damage were lower, and no drug-related deaths were observed. These results show that use of the NH4EDTA gradient method to load doxorubicin into liposomes could significantly reduce drug toxicity without influencing antitumor activity.

The Current and Future Therapies for Human Osteosarcoma

Osteosarcoma (OS) is the most common non-hematologic malignant tumor of bone in adults and children. As sarcomas are more common in adolescents and young adults than most other forms of cancer, there are a significant number of years of life lost secondary to these malignancies. OS is associated with a poor prognosis secondary to a high grade at presentation, resistance to chemotherapy and a propensity to metastasize to the lungs. Current OS management involves both chemotherapy and surgery. The incorporation of cytotoxic chemotherapy into therapeutic regimens escalated cure rates from <20% to current levels of 65-75%. Furthermore, limb-salvage surgery is now offered to the majority of OS patients. Despite advances in chemotherapy and surgical techniques over the past three decades, there has been stagnation in patient survival outcome improvement, especially in patients with metastatic OS. Thus, there is a critical need to identify novel and directed therapy for OS. Several Phase I trials for sarcoma therapies currently ongoing or recently completed have shown objective responses in OS. Novel drug delivery mechanisms are currently under phase II and III clinical trials. Furthermore, there is an abundance of preclinical research which holds great promise in the development of future OS-directed therapeutics. Our continuously improving knowledge of the molecular and cell-signaling pathways involved in OS will translate into more effective therapies for OS and ultimately improved patient survival. The present review will provide an overview of current therapies, ongoing clinical trials and therapeutic targets under investigation for OS.

Osteosarcoma: review of the past, impact on the future. The American experience

Major advances have been achieved in the treatment of osteosarcoma with the discovery of several chemotherapeutic agents that were active in the disease. These agents comprise high-dose methotrexate with leucovorin rescue, Adriamycin, cisplatin, ifosfamide and cyclophosphamide. The agents were integrated into various regimens and administered in an effort to destroy silent pulmonary micrometastases which are considered to be present in at least 80% of patients at the time of diagnosis. Their efficacy in achieving this goal was realized and their use was further extended to the application of preoperative (neoadjuvant) chemotherapy to destroy the primary tumor and achieve safe surgical resections. Disease free survival was escalated from <20% prior to the introduction of effective chemotherapy to 55-75% and overall survival to 85%. Further, the opportunity to perform limb salvage was expanded to 80% of patients. Of interest also was an attempt in one series to treat the primary tumor exclusively with chemotherapy, and abrogation of surgery. Adding to these advances, varieties of subsequently discovered agents are currently undergoing investigations in patients who have relapsed and/or failed conventional therapy. The agents include Gemcitabine, Docetaxel, novel antifolate compounds, and a liposome formulation of adriamycin (Doxil). A biological agent, muramyl tripeptide phosphatidyl ethanolamine (MTPPE) was also recently investigated in a 2x2 factorial design to determine its efficacy in combination with chemotherapy (methotrexate, cisplatin, Adriamycin and ifosfamide).In circumstances where the tumor was considered inoperable, chemotherapy and radiotherapy were advocated for local control. High dose methotrexate, Adriamycin and cisplatin and Gemcitabine interact with radiation therapy and potentiate its therapeutic effect. This combination is also particularly useful in palliation. Occasionally, the combination of radiation and chemotherapy may render a tumor suitable for surgical ablation. Samarium153, a radio active agent, is also used as palliative therapy for bone metastases.However, despite the advances achieved with the multidisciplinary application of chemotherapy, radiotherapy and surgical ablation of the primary tumor over the past 3(1/2) decades, the improved cure rate reported initially has not altered. Particularly vexing is the problem of rescuing patients who develop pulmonary metastases after receiving seemingly effective multidisciplinary treatment. Approximately 15-25% of such patients only are rendered free of disease with the reintroduction of chemotherapy and resection of metastases. Extrapulmonary metastases and multifocal osteosarcoma also constitute a major problem. The arsenal of available agents to treat such patients has not made any substantial impact in improving their survival. New chemotherapeutic agents are urgently required to improve treatment and outcome. Additional strategies to be considered are targeted tumor therapy, anti tumor angiogenesis, biotherapy and therapy based upon molecular profiles. This communication outlines sequential discoveries in the chemotherapeutic research of osteosarcoma in the United States of America. It also describes the principles regulating the therapeutic application of the regimens and considers the impact of their results on the conduct in the design of future investigations and treatment.

New insights into doxorubicin-induced cardiotoxicity: the critical role of cellular energetics

Cardiotoxic side-effects represent a serious complication of anticancer therapy with anthracyclines, in particular with doxorubicin (DXR) being the leading drug of the group. Different hypotheses, accentuating various mechanisms and/or targets, have been proposed to explain DXR-induced cardiotoxicity. This review focuses on the myocardial energetic network as a target of DXR toxic action in heart and highlights the recent advances in understanding its role in development of the DXR related cardiac dysfunction. We present a survey of DXR-induced defects in different steps of cardiac energy metabolism, including reduction of oxidative capacity of mitochondria, changes in the profile of energy substrate utilization, disturbance of energy transfer between sites of energy production and consumption, as well as defects in energy signaling. Considering the wide spectrum and diversity of the changes reported, we attempt to integrate these facts into a common framework and to discuss important functional and temporal relationships between DXR-induced events and the possible underlying molecular mechanisms.

Long-term serial echocardiographic examination of late anthracycline cardiotoxicity and its prevention by dexrazoxane in paediatric patients

The authors conducted an 8-year prospective non-randomised study to determine whether dexrazoxane (ICRF-187) would reduce late anthracycline-induced cardiotoxicity in patients treated in childhood for haematological malignancy. The authors examined prospectively 75 patients (40 male/35 female) aged 2-17 years (median 6.5 years) at the time of diagnosis. The cardioprotection was given to 53 patients (26 male/17 female) and the standard protocol was used in 22 patients (14 male/8 female). The prospective echocardiographic evaluation was done before and after the chemotherapy and every year during the follow-up period. Dynamic stress echocardiography (DSE) was assessed in the final year. The clinical cardiotoxicity was not diagnosed. Higher cumulative doses of anthracycline were given in the dexrazoxane group (234+/-58 mg/m(2), median 240 mg/m(2) versus 203+/-86 mg/m(2), median 210 mg/m(2), P <0.04) and a significantly higher percentage of patients received cumulative doses >240 mg/m(2) of anthracycline ( P <0.05). During the follow-up period, the fractional shortening (FS) declined in the no-dexrazoxane group only in the 8th year and was significantly lower compared to the dexrazoxane group ( P <0.05). The pathological decrease in FS was present in 24% of patients; 41% in the no-dexrazoxane and 17% in the dexrazoxane groups, respectively ( P <0.05). DSE demonstrated lower rest EF and cardiac index (CI) in the no-dexrazoxane group ( P <0.05); however, neither the response of EF and CI to the stress echocardiography nor the exercise tolerance significantly differed between sub-groups. A higher number of patients in the dexrazoxane group had very good exercise tolerance (ET) >3 Watts/kg ( P <0.05) and a lower number responded with a decreased ET <2 Watts/kg ( P <0.05) compared to the no-dexrazoxane group.

CONCLUSION

Dexrazoxane seems to reduce the risk of late subclinical cardiotoxicity. Dexrazoxane-treated patients revealed better exercise tolerance; however the haemodynamic response to the stress was no different in both sub-groups.

The role of pixantrone in the treatment of non-Hodgkin’s lymphoma

Pixantrone is an anthraquinone-based inhibitor of topoisomerase II. It is similar to both the anthracycline doxorubicin and the anthracenedione mitoxantrone, but lacks the 5,8-dihydroxy substitution pattern of mitoxantrone, and has a tricyclic system unlike the tetracyclic structure seen with anthracyclines. Anthracyclines are the most active drugs in lymphoma therapy, but their use is limited by their cumulative and irreversible cardiotoxicity. Pixantrone was developed to improve the toxicity profile of the current anthracyclines and anthracenediones while maintaining their activity. Interestingly, pixantrone showed no measurable cardiotoxicity compared with its parent compound mitoxantrone or other anthracyclines at equi-effective doses in several animal models. Together with its superior cytotoxic activity in leukaemia and lymphoma models, these features render the drug a promising candidate for clinical development in indolent and aggressive non-Hodgkin's lymphoma. In this review, the latest results of the use of pixantrone in indolen-t and aggressive non-Hodgkin's lymphomas are summarised.

Late anthracycline cardiotoxicity protection by dexrazoxane (ICRF-187) in pediatric patients: echocardiographic follow-up

BACKGROUND

The authors conducted a retrospective study to determine whether dexrazoxane (ICRF-187) would reduce late anthracycline-induced cardiotoxicity in patients treated in childhood for hematological malignancy.

PATIENTS AND METHODS

The authors examined 108 patients (63 male, 45 female) 5-29 years old, (median 15 years). All patients were in long-term remission of their malignancy. The cardioprotection was given to 68 patients (39 male, 29 female), and standard treatment was used in 40 patients (24 male, 16 female). Dexrazoxane (cardioxane, Chiron Company, The Netherlands) was given in 20:1 ratio to anthracycline. The follow-up time was 2-20 years (mean 7 years). The control group consisted of 41 volunteers (22 males, 19 females) 4-31 years old (median 18 years). The cardiotoxicity has been defined as the presence of heart failure or the decline of shortening fraction below 30% or ejection fraction (EF) below 55%. The end-systolic wall stress (ESS), myocardial performance index (MPI; Tei index), and parameters of left ventricular diastolic filling were also assessed.

RESULTS

The anthracycline cardiomyopathy with the presence of heart failure was diagnosed in only one patient treated with a standard regimen. The pathological decline of fractional shortening was present in three (5%) and six (15%) patients with and without cardioprotection given, respectively. Similarly, none of the patients with cardioprotection revealed a pathological value of EF, while four (10%) patients without cardioprotection showed an EF decrease. Finally, ESS and isovolumic relaxation time were pathologically increased in the group without cardioprotection in comparison to the controls and to the group with cardioprotection. However, the MPI was significantly increased in both groups of patients.

CONCLUSIONS

Dexrazoxane reduces the risk of late clinical and subclinical cardiotoxicity and does not affect the response rates to chemotherapy and overall survival during the median follow-up period of 7 years (follow-up period 2-20 years).

Long-term clinical outcome after accidental overdose of multiple chemotherapeutic agents

Treatment of non-Hodgkin's lymphoma with the CHOP regimen consists of intravenous cyclophosphamide 750 mg/m2 (day 1), intravenous doxorubicin 50 mg/m2 (day 1), intravenous vincristine 1.4 mg/m2 (day 1), and oral prednisone 100 mg (days 1-5). This regimen is administered in cycles of approximately 3 weeks; a total course of treatment consists of six cycles. We report the case of a 23-year-old woman with diffuse large-cell lymphoma who received an accidental overdose of this chemotherapeutic regimen. The first cycle of her CHOP regimen was initiated (day 1) in our outpatient unit; she was then discharged home. Unfortunately, the patient went to another hospital located in the small city where she lived, and all remaining doses of the total course of treatment were administered over the next 5 consecutive days, with no interruption in therapy. She had received cumulative doses of cyclophosphamide 6000 mg, doxorubicin 420 mg, and vincristine 12 mg. She was transferred to our hospital after she developed pancytopenia, fever, and ileus. With the help of intensive supportive care and symptomatic treatment, the patient recovered and was discharged home after a hospital stay of 25 days. After 56 months, she was free of disease and treatment-related toxicities. Only experienced clinicians should administer chemotherapy, and thorough records must be kept to document the chemotherapy administered, dosages, dates of administration, the procedure used, and the schedule of cycles administered.

Modification of doxorubicin-induced cardiotoxicity: manipulation of the dosage schedule

Modification of the dosing schedule for doxorubicin (DOX) administration represents a possible method of reducing cardiotoxicity from this potent anti-cancer drug, while at the same time maintaining its cytotoxic action. The quantitative effects of modified dosage scheduling have been investigated in a clinically relevant rat model. Cardiotoxicity to DOX was assessed by the degree of reduction in cardiac output at 4-24 weeks after the intravenous administration of DOX. The effects of dose schedules involving three or six small dose administrations, over one and two weeks, were compared with that produced by large single doses of DOX. The total drug dose administered for each schedule was varied in order to establish dose-effect relationships. After a total dose of 3 mg/kg DOX, given as three or six equal small doses, there was a gradual decline in cardiac output in the first 12 weeks after drug administration. Between 12 and 24 weeks, the reduction in cardiac function was relatively stable at between 65% and 85% of that of age-matched controls for three and six equal small doses, respectively. Dose-effect curves for animals showing a > or = 30% reduction in cardiac function after 12 weeks indicated the degree of reduction in cardiac function produced by the modified dose scheduling. Compared with a large single dose, larger total doses were required to produce the same severity of damage. Thus, schedules based on three and six equal small doses resulted in dose modification factor of 1.5 +/- 0.23 and 2.1 +/- 0.28, respectively, when compared with the same effect produced by a large single dose. This appeared to be independent of the severity of cardiac damage, suggesting a simple mathematical relationship between the total acceptable dose of DOX and the dose administered at each intravenous injection. These modifications in the cardiotoxicity of DOX produced by the administration of multiple small doses were of the same order of magnitude as that produced by other methods introduced to reduce anthracycline cardiotoxicity.

The clinical value of nuclear medicine in the assessment of irradiation-induced and anthracycline-associated cardiac damage

Two groups of patients, those treated for Hodgkin's disease and breast cancer, are particularly at risk of developing late myocardial damage, since radiotherapy (RT) techniques for both patient groups may include (large) parts of the heart, and adjuvant systemic therapy is frequently administered to these patients, in particular anthracycline-containing chemotherapy. Available literature on the monitoring and prediction of RT-induced and anthracycline-associated cardiac damage using nuclear medicine techniques is presented. Based on relevant studies, the risk of overall cardiac disease post-RT and overt congestive heart failure during anthracycline-containing chemotherapy is probably low. Conventional nuclear medicine imaging, i.e. myocardial perfusion scintigraphy, may be of complementary use to echocardiographical evaluation for routine follow-up after RT with modern techniques, in a subgroup of patients with known cardiovascular risk factors. Left ventricle ejection fraction (LVEF) measurements, as assessed by radionuclide angiography for the monitoring of anthracycline-associated cardiac injury, are not very sensitive and early detection will probably be enhanced by combining LVEF measurements with other cardiac function parameters. Also, it may be expected that nuclear medicine techniques using molecular radioligands will constitute an essential future step in the evaluation of subclinical cardiac injury afforded by the combined effect of RT and cardiotoxic chemotherapy.

Inhibition of doxorubicin chronic toxicity in catalase-overexpressing transgenic mouse hearts

Catalase is an important antioxidant enzyme, which has been shown to provide cardiac protection from acute toxicity induced by doxorubicin, a most effective anticancer agent. Because cumulative dose-dependent chronic cardiomyopathy due to a long-term administration of doxorubicin is a significant clinical problem, the present study was undertaken to test the hypothesis that catalase also provides protection against doxorubicin chronic cardiotoxicity. Transgenic mice containing cardiac catalase activities of 15-, 60-, or 100-fold higher than normal and nontransgenic controls were treated with doxorubicin in a cumulative dose of 45 mg/kg in five equal iv injections (9 mg/kg every other week) over a period of 10 weeks. On the second day after the last injection, the mice were sacrificed for analysis of cardiotoxicity. As compared to nontransgenic controls, doxorubicin-reduced body weight gain was significantly inhibited in the transgenic mice. There were 15% mortality in nontransgenic mice, but no mortality was observed in transgenic mice during the course of treatment. Light microscopic examination revealed that doxorubicin-induced myocardial morphological changes were markedly suppressed in the transgenic mice in an activity-dependent fashion. Under electron microscopy, extensive sarcoplasmic vacuolization and severe disruption of mitochondrial fine structure were observed in nontransgenic cardiomyocytes, but all markedly suppressed in the transgenic mice. The results indicate that catalase elevation in the heart prevents doxorubicin chronic cardiomyopathy.

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 ( approximately 2.5%). Measurements of cardiac volume output made at various intervals after DOX administration indicated a approximately 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 approximately 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.

Phase I study of BBR 2778, a new aza-anthracenedione, in advanced or refractory non-Hodgkin's lymphoma

BACKGROUND

BBR 2778 is a novel aza-anthracenedione showing no cardiotoxicity and superior activity compared to doxorubicin and mitoxantrone in animal models. Objectives of this phase I study included the determination of the maximum tolerated dose (MTD), the dose limiting toxicity (DLT), clinical pharmacokinetics (PK), and antitumor activity. Patients with relapsed or refractory, advanced non-Hodgkin's lymphoma were included.

PATIENTS AND METHODS

Patients were treated with a q1w x 3 schedule on the basis of a modified Fibonacci dose escalation method. Seven groups with a total of twenty-six patients were treated at dosages of 5, 10, 16.5, 25, 34, 56 or 84 mg/m2/w, respectively.

RESULTS

DLT was observed on the seventh dose level with neutropenia WHO grade 4 in three of six patients. Pharmacokinetic analysis showed a large volume of distribution (13.5-17.5 l/kg), a high plasma clearance (0.65-1.74 l/h/kg) and a long elimination half-life (14.7-31.9 h). Tumor response included three complete remissions and two partial remissions.

CONCLUSIONS

Neutropenia is the DLT of the new aza-anthracenedione BBR 2778. The recommend dose is 84 mg/m2 in a q1w x 3 schedule. PK data are consistent with a linear kinetic of BBR 2778 comparable to mitoxantrone. This new drug shows promising activity in intensively pretreated patients with relapsed or refractory NHL. Based on this results, phase II studies with this new compound are underway.

Phase II trial of pre-irradiation KRN8602 (MX2) in malignant glioma patients

KRN8602 (MX2) is a newly developed morpholino anthracycline that crosses the blood-brain barrier where it becomes distributed in brain tissue after intravenous administration. This morpholino anthracycline has been found to be effective against human glioma cells and the intracerebrally transplanted tumors in vivo, We performed a phase II trial using KRN8602 as a single agent in malignant glioma patients who had not received prior adjuvant therapy. The 13 patients (5 glioblastomas, 7 anaplastic astrocytomas and 1 malignant oligodendroglioma) enrolled received at least 1 cycle of KRN8602 at 35 mg/m2/day in 3-4 week intervals by intravenous bolus. Ten of these patients could be evaluated for response, and 13 for toxicity. Three patients (1 glioblastoma and 2 anaplastic astrocytomas) demonstrated a complete response (3/10, 30%). Concerning side effects, myelosuppression was moderately severe, with 30.7% of patients developing grade 3 leukopenia. Severe nausea/vomiting was observed in 69% of the patients, however, cardiotoxicity was not observed. The results indicate that KRN8602 demonstrated modest activity against malignant glioma with relatively severe, but manageable toxicity. Further assessment of the efficacy and toxicity of KRN8602 against malignant glioma may be worthwhile.

Suppression by metallothionein of doxorubicin-induced cardiomyocyte apoptosis through inhibition of p38 mitogen-activated protein kinases

Cardiomyopathy induced by doxorubicin (DOX) has long been a major impediment of clinical applications of this effective anticancer agent. Previous studies have shown that cardiac-specific metallothionein (MT)-overexpressing transgenic mice are highly resistant to DOX-induced cardiotoxicity. To investigate cellular and molecular mechanisms by which MT participates in this cytoprotection, transgenic mice containing high levels of cardiac MT and non-transgenic controls were treated intraperitoneally with DOX at a single dose of 15 mg/kg and sacrificed on the 4th day after treatment. Myocardial apoptosis was detected by a terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay and confirmed by electron microscopy of immunogold staining of apoptotic nuclei. Dual staining of cardiac alpha-sarcomeric actin using an immunohistochemical method further identified apoptotic myocytes. Apoptosis was significantly inhibited in the transgenic myocardium. The anti-apoptotic effect of MT was further revealed in primary cultures of neonatal mouse cardiomyocytes. Furthermore, DOX activated p38 mitogen-activated protein kinase (MAPK), which was critically involved in the apoptotic process, as demonstrated by inhibition of DOX-induced apoptosis by a p38-specific inhibitor, SB203580. Both DOX-induced p38 MAPK activation and apoptosis were dramatically inhibited in the transgenic cardiomyocytes. The results thus demonstrate that DOX induces apoptosis in cardiomyocytes both in vivo and in vitro and MT suppresses this effect through at least in part inhibition of p38 MAPK activation.

Phase I and subsequent phase II study of filgrastim (r-met-HuG-CSF) and dose intensified cyclophosphamide plus epirubicin in patients with non-Hodgkin's lymphoma and advanced solid tumors

BACKGROUND

To define a maximum tolerated dose (MTD) for the combination of epirubicin and cyclophosphamide with filgrastim (r-met-HuG-CSF) in patients with advanced solid tumors and non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Thirty-five patients with advanced solid tumors were enrolled in stages I and II. Twenty-one patients were treated in stage I in sequential cohorts of at least three patients at increasing dosage levels of cyclophosphamide and epirubicin, for up to six cycles every 21 days. At the completion of stage I, a MTD for epirubicin was established. Fourteen patients were treated in stage II, in cohorts of three or more. The epirubicin dose remained constant at the MTD dosage from stage I. Cyclophosphamide was further dose-escalated to establish its MTD. Twenty-one patients with previously untreated non-Hodgkin's lymphoma were treated in stage III with the MTD established in the prior stages.

RESULTS

The MTD in stage I was epirubicin 150 mg/m2 and cyclophosphamide 1500 mg/m2 with cumulative neutropenia as the dose-limiting toxicity (DLT). Cumulative thrombocytopenia prevented further dose-escalation of cyclophosphamide in stage II. The stage III regimen consisted of six, 21-day cycles of epirubicin 150 mg/m2, cyclophosphamide 1500 mg/m2, vincristine 2 mg, and prednisolone 100 mg for five days with filgrastim support. Nineteen of twenty-one patients (90%) completed six cycles of treatment, eight (38%) without dose reduction. Common toxicity criteria (CTC) grade 4 neutropenia (neutrophil nadir < 0.5 x 10(9)/l) was documented in 85 of 118 cycles (72%). Neutropenic fever was documented in 17 of 21 patients (81%) on at least one occasion. Severe thrombocytopenia (< 25 x 10(9)/l) was seen in fourteen of 118 cycles (12%) and increased with cycle number. There was no significant non-hematological toxicity.

CONCLUSION

Significant dose-escalation of epirubicin and cyclophosphamide was possible with filgrastim support. The MTD achieved was approximately double that of standard-dose therapy. This study forms the basis of an ongoing randomized study evaluating dose-intensification in intermediate grade NHL.

Phase II trial of liposome-encapsulated doxorubicin, cyclophosphamide, and fluorouracil as first-line therapy in patients with metastatic breast cancer

PURPOSE

To determine the efficacy and safety profile, including the risk for cardiac toxicity, of liposome-encapsulated doxorubicin (TLC D-99), fluorouracil (5-FU), and cyclophosphamide as first-line chemotherapy in patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS

Forty-one women were registered in this phase II study. All patients had measurable disease and no previous chemotherapy for MBC. Treatment consisted of TLC D-99 60 mg/m2 and cyclophosphamide 500 mg/m2 on day 1 and 5-FU 500 mg/m2 on days 1 and 8 every 3 weeks. Serial cardiac monitoring, including endomyocardial biopsies, was performed.

RESULTS

The overall response rate was 73% (95% confidence interval, 57% to 86%). The median duration of response was 11.2 months, the median time to treatment failure was 8.1 months, and the median overall survival duration was 19.4 months. The median number of cycles per patient was 10. The median cumulative dose of TLC D-99 was 528 mg/m2. Ten patients required hospitalization for febrile neutropenia. Nausea/vomiting, stomatitis, and fatigue higher than grade 2 occurred in 12%, 15%, and 41% of patients, respectively. Twenty-one patients reached a cumulative doxorubicin dose greater than 500 mg/m2. Three patients (7%) were withdrawn from the study due to protocol-defined cardiac toxicity, two because of a decrease in left ventricular ejection fraction to < or = 40%, and one because her endomyocardial biopsy result was grade 1.5. One patient had congestive heart failure that was probably nonanthracycline related.

CONCLUSION

This chemotherapy regimen, including TLC D-99, was highly active against MBC and associated with low cardiac toxicity despite high cumulative doses of doxorubicin.

Phase II trial of high-dose liposome-encapsulated doxorubicin with granulocyte colony-stimulating factor in metastatic breast cancer. TLC D-99 Study Group

PURPOSE

To estimate the toxicity and response rate of high-dose liposome-encapsulated doxorubicin (TLC D-99, Evacet, The Liposome Company Inc, Princeton, NJ) in patients with advanced breast cancer.

PATIENTS AND METHODS

Fifty-two breast cancer patients with bidimensionally measurable metastatic disease and no prior chemotherapy for metastatic disease received a 135 mg/m2 intravenous (i.v.) bolus of TLC D-99 with 5 microg/kg of granulocyte colony-stimulating factor via subcutaneous injection every 21 days.

RESULTS

The median number of treatment cycles of TLC D-99 was three (range, one to 10 cycles), and the median total cumulative dose of TLC D-99 was 405 mg/m2 (range, 135 to 1,065 mg/m2). Grade IV neutropenia, thrombocytopenia, and mucositis were experienced by 48 (92%), 46 (88%), and 10 (19%) patients, respectively. Twenty (38%) of patients experienced cardiac toxicity: four (8%) experienced a decrease of 20% or more in left ventricular ejection fraction (LVEF) to a final value > or = 50%, nine (17%) experienced a decrease of 10% or more in LVEF to a final value less than 50%, and seven (13%) developed symptomatic congestive heart failure (CHF), including one patient who died of cardiomyopathy after receiving a total dose of 1,035 mg/m2. In a stepwise logistic regression model, the significant risk factors for the development of CHF were the cumulative dose of prior adjuvant doxorubicin (P = .007) and the total cumulative dose of TLC D-99 (P = .032). The overall response rate was 46% (95% confidence interval [CI], 32% to 61%) on an intent-to-treat basis. The median duration of response was 7.4 months (95% CI, 6.1 to 19.6 months) and the median progression-free survival was 6.1 months (95% CI, 5.4 to 7.5 months).

CONCLUSION

There was no added therapeutic benefit to the dose escalation of TLC D-99 in this study. A high rate of cardiotoxicity was also observed, especially among patients who had received prior adjuvant doxorubicin. This was probably attributable to the dose and schedule of TLC D-99 used in this trial, as well as the patient's lifetime cumulative doxorubicin dose. Administration of high-dose TLC D-99 at 135 mg/m2 every 3 weeks by i.v. bolus infusion does not warrant further investigation.

The role of chemotherapy for metastatic breast cancer

Metastatic breast cancer remains a devastating and largely incurable disease. Currently available therapies offer meaningful palliation for many and modest prolongation of survival for some patients. Single-agent hormonal therapy remains the treatment of choice for patients with ER-positive disease, with sequential use of further hormonal agents or cytotoxic chemotherapy at the time of disease progression. Chemotherapy is appropriate as initial therapy for patients with receptor-negative or rapidly progressive visceral disease. Although combination regimens may increase response rates, the lack of survival benefit does not justify the increased toxicity of aggressive combination regimens in most patients. Maintenance chemotherapy deserves consideration in selected well-informed patients, especially those with few therapy-related side effects. High-dose regimens confer substantial toxicity with no clear therapeutic advantage and cannot be recommended outside of ongoing trials. New chemotherapy agents offer the hope of effective salvage therapy with acceptable toxicity to a larger number of patients. Perhaps most promising, the development of targeted, biologically based therapies such as rhuMAbHER2 offers encouragement for the future.

Structural and functional impairment of mitochondria in adriamycin-induced cardiomyopathy in mice: suppression of cytochrome c oxidase II gene expression

The use of adriamycin (ADR) in cancer chemotherapy has been limited due to its cumulative cardiovascular toxicity. Earlier observations that ADR interacts with mitochondrial cytochrome c oxidase (COX) and suppresses its enzyme activity led us to investigate ADR's action on the cardiovascular functions and heart mitochondrial morphology in Balb-c mice i.p. treated with ADR for several weeks. At various times during treatment, the animals were assessed for cardiovascular functions by electrocardiography and for heart tissue damage by electron microscopy. In parallel, total RNA was extracted from samples of dissected heart and analyzed by Northern blot hybridization to determine the steady-state level of three RNA transcripts encoded by the COXII, COXIII, and COXIV genes. Similarly, samples obtained from the liver of the same animals were analyzed for comparative studies. Our results indicated that 1) treatment of mice with ADR caused cardiovascular arrhythmias characterized by bradycardia, extension of ventricular depolarization time (tQRS), and failure of QRS at high concentrations (10-14 mg/kg body weight cumulative dose); 2) the heart mitochondria underwent swelling, fusion, dissolution, and/or disruption of mitochondrial cristae after several weeks of treatment. Such abnormalities were not observed in the mitochondria of liver tissue; and 3) among the three genes of COX enzyme examined, only COXII gene expression was suppressed by ADR treatment, mainly after 8 weeks in both heart and liver. Knowing that heart mitochondria represent almost 40% of heart muscle by weight, we conclude that the deteriorating effects of ADR on cardiovascular function involve mitochondrial structural and functional impairment.

Early detection of anthracycline-induced cardiotoxicity by radionuclide angiocardiography

For the early detection of myocardial damage associated with anthracycline therapy, electrocardiography, echocardiography, and radionuclide angiocardiography were used to assess cardiac function in 37 patients receiving anthracyclines (ie, adriamycin and daunorubicin at a total dose of 100-2,030 mg/m2). None of the patients developed clinical congestive heart failure. There were no significant changes of electrocardiographic and echocardiographic parameters after anthracycline administration. The left ventricular ejection fraction did not change significantly on radionuclide angiocardiography. However, the 1/3 peak filling rate (PFR) corrected by the end-diastolic count (EDC) (1/3 PFR/EDC) and the 1/3 filling fraction (1/3 FF), the indices of early diastolic function, showed a significant decrease. These findings suggest that the 1/3 PFR/EDC and 1/3 FF determined by radionuclide imaging are useful for detecting silent myocardial damage induced by anthracyclines.

Dexrazoxane (ICRF-187)

1. Dexrazoxane (ICRF-187) is the only clinically approved drug for use in cancer patients to prevent anthracycline mediated cardiotoxicity. 2. The mode of action appears to be mainly due to the potential of the drug to remove iron from iron/anthracycline complexes and thus reduce free radical formation by these complexes. 3. Dexrazoxane also influences cell biology by its ability to inhibit topoisomerase II and its effects on the regulation of cellular iron homeostasis. 4. Although the cardioprotective effect of dexrazoxane in cancer patients undergoing chemotherapy with anthracyclines is well documented, the potential of this drug to modulate topoisomerase II activity and cellular iron metabolism may hold the key for future applications of dexrazoxane in cancer therapy, immunology, or infectious diseases.

Cardiac effects of high-dose epirubicin and cyclophosphamide in women with poor prognosis breast cancer

PURPOSE

To prospectively evaluate the long term cardiac effects of high-dose epirubicin and cyclophosphamide given to women with early stage, poor prognosis breast cancer.

PATIENTS AND METHODS

Women with stage 2 breast cancer and 10+ nodes or 4+ nodes and estrogen receptor negative tumor, or stage 3 breast cancer received three cycles of epirubicin 200 mg/m2 and cyclophosphamide 4 gm/m2 with peripheral blood progenitor cell and filgrastim support. Treatment was given every 28 days (n = 79) or 21 days (n = 20). Fifty patients received radiotherapy to the chest wall or breast, 25 of to the left side. Patients were assessed clinically regularly during chemotherapy and at least three times yearly after completion of treatment. Cardiac left ventricular ejection fraction (LVEF) was assessed by radionuclide scan before therapy, after each cycle of chemotherapy, three months and six months after completion of chemotherapy, and yearly thereafter until relapse.

RESULTS

Ninety-nine women were treated, and 92 completed all three cycles of chemotherapy. The median age was 43 years (range 24 to 60 years). All patients were included in this analysis. The median relapse-free survival was 39 months (11 to 68 months). There was a significant fall in LVEF during chemotherapy. In general, there was no further deterioration in cardiac function from the third month after cessation of treatment, however there was substantial variation between individuals. 35 patients had at least one LVEF measure less than normal (< 50%), but the LVEF returned to normal in 20 of these with further follow-up. Cardiac dysfunction was not increased in women who received radiotherapy and was not different between cohorts given chemotherapy every three or every four weeks. One patient died of acute myocardial necrosis following the third cycle of chemotherapy. Two patients developed clinical evidence of cardiac failure, and another had radiological signs but was asymptomatic. One woman died of progressive cardiac failure, one recovered clinically but also developed recurrent breast cancer, while the third recovered after commencement of medical therapy.

CONCLUSIONS

During follow-up after high-dose epirubicin and cyclophosphamide as delivered in this study, the LVEF fell to below normal in approximately one third of patients. However, in over half of these patients the LVEF subsequently recovered to the normal range, and the incidence of clinically evident chronic cardiac failure was low. Further follow-up is required to assess the long-term safety. A randomized comparison with standard-dose anthracycline-based chemotherapy is needed to determine whether this regimen is associated with an increased risk of clinical cardiac toxicity.

Does the multidrug-resistance modulator cyclosporin A increase the cardiotoxicity of high-dose anthracycline chemotherapy?

Cyclosporin A has heterogeneous effects on anthracycline-related cardiotoxicity and can prevent multidrug-resistance (MDR). The aim of this study was to explore whether the coadministration of cyclosporin A is accompanied by an increase in cardiotoxicity. Forty-three patients (27 male, 16 female, age: 18-67 yrs [mean: 47.5 yrs, SD: 11.6 yrs]) received 177 radionuclide ventriculography examinations (RNV 177 at rest, 133 at stress) before and during chemotherapy with either doxorubicin (n = 23) or epirubicin (n = 20). RNV studies were applied up to 11 times in the follow-up of the patients. A maximum of 10 courses of chemotherapy was performed. In the doxorubicin group only, the age of the patients and the cumulative dose of the chemotherapeutic agent had a significant negative impact on left ventricular ejection fractions, whereas cyclosporin A had a significant positive influence (multiple analysis of regression, p < 0.05). Cyclosporin A did not cause any significant increase in cardiotoxicity in our patients.

Preclinical toxicology of a novel polymeric antitumour agent: HPMA copolymer-doxorubicin (PK1)

N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin (PK1) is a novel polymeric anticancer agent containing doxorubicin (approximately 8 wt%) bound to the polymer backbone via a Gly-Phe-Leu-Gly peptidyl linker. The approximate LD50 of PK1 in MF1 mice after a single i.v. injection was 63 mg/kg (doxorubicin-equivalent). Single doses of PK1 were administered to MF1 mice at 22.5 or 45 mg/kg and blood samples taken on days 3, 7 and 14 for haematological examination and clinical chemistry. At day 14 all animals were sacrificed for necropsy. In a multiple dose study, PK1 was administered i.v. to MF1 mice or Wistar rats (20 animals per group) weekly for five consecutive weeks at doses of 12.0 or 22.5 mg/kg (mice) or 3 and 5 mg/kg (rats). After 31 days 10 animals from each group were sacrificed for necropsy and the remainder were sacrificed after 59 days. Blood samples were taken 3 days after administration of each dose and at the end of the experiment, and urine samples were collected on the day prior to sacrifice. Mortality in the single dose mouse and multiple dose rat studies was low. In the multiple dose mouse study 4/10 animals were killed in extremis before the scheduled day 31 and all animals died before day 37. PK1 induced a reduction in WBC and platelets in rats and mice shortly after treatment and RBC at later times, and in the single dose study alanine and aspartate aminotransferase levels were elevated at higher doses. Liver damage was seen only in rat tissue during histological examination. Other histological changes induced by PK1 include thymic and testicular atrophy, bone marrow depletion gastrointestinal tract changes and in the multiple dose study an increase in nuclear size in the proximal tubules of the kidney (although no changes in urine were seen). Recovery from these effects was seen in rats at 59 days. A PK1 dose of 20 mg/m2 (doxorubicin equivalent) was recommended as a safe dose for the start of Phase I clinical trials.

Anthracyclines in haematology: preclinical studies, toxicity and delivery systems

The anthracyclines are widely used in the treatment of haematological and non-haematological malignancy and there is now more than 30 years' clinical experience with these agents but despite this, their mechanism of action is incompletely understood. The anthracyclines have been shown to intercalate with DNA and indirectly inhibit the activity of the enzyme topoisomerase II, resulting in DNA strand breaks. More recently, workers have focused on induction of apoptosis and have shown that daunorubicin stimulates production of the apoptotic mediator, ceramide and that the activity of doxorubicin can be blocked by inhibitors of CD95 (fas). One of the major problems with anthracycline therapy is the development of resistance which may be mediated by p-glycoprotein or by other mechanisms. Much recent research has concentrated on methods to modulate the drug-resistant phenotype and these include development of new analogues and use of specific reversal agents. The toxicity profile of the anthracyclines includes bone marrow suppression, severe local reaction following extravasation, radiation recall, alopecia, gastrointestinal and hepatic effects, development of secondary malignancies and significant cardiac toxicity. The risk factors for the development of anthracycline-related cardiac toxicity are well documented and several methods have been exploited in attempts at prevention. Finally, a number of drug delivery systems have been developed in order to improve therapeutic response and reduce toxicity to normal tissues, including the use of liposomal preparations.

Modulation of transferrin receptor expression by dexrazoxane (ICRF-187) via activation of iron regulatory protein

Dexrazoxane (ICRF-187) has recently been demonstrated to reduce cardiac toxicity induced by chemotherapy with anthracyclines, although the reason for this phenomenon has remained obscure thus far. In order to investigate whether ICRF-187 might exert its effects by modulating iron metabolism, we studied the drug's potential to influence the maintenance of iron homeostasis in two human cell lines. We demonstrate that ICRF-187 enhanced the binding affinity of iron regulatory protein (IRP), the central regulatory factor for posttranscriptional iron regulation, to RNA stem loop structures, called iron responsive elements (IRE), in THP-1 myelomonocytic as well as K562 erythroleukemic cells. Increased IRE/IRP interaction was paralleled by an elevation of transferrin receptor (trf-rec) mRNA levels which, according to the well-established mechanism of posttranscriptional iron regulation, was likely due to stabilisation of trf-rec mRNA by IRP. Subsequently, ICRF-187 treatment of cells increased trf-rec surface expression and enhanced cellular iron uptake. All these events, i.e. IRP activation, stabilisation of trf-rec mRNA and increased surface expression of the protein in response to ICRF-187, follow a dose-response relationship. Increased cellular uptake and sequestration of iron in response to ICRF-187 may contribute to the protective activity of ICRF-187 by reducing the iron-anthracycline complex and iron-catalysed generation of hydroxyl radicals via the Haber-Weiss reaction.

A risk-benefit assessment of anthracycline antibiotics in antineoplastic therapy

The anthracycline antibiotics comprise a group of cytotoxic compounds with wide-ranging activity against human malignancies. They are used extensively for curative, adjuvant and palliative therapy, both as single agents and in combination regimens. They produce a number of adverse effects, some of which are shared by other cytotoxic drugs. The most important adverse effect is cardiotoxicity, which is unique to this class of compounds. Strategies have been devised to circumvent these adverse effects, including the development of less toxic analogues, alterations in scheduling, the addition of cardioprotectant agents and methods of monitoring for cardiac abnormalities.

Cardioprotection by dexrazoxane (Cardioxane; ICRF 187): progress in supportive care

The dose-limiting toxicity of the widely used anticancer agent, doxorubicin, is a destructive, irreversible and progressive cardiomyopathy. Prevention of this cardiotoxicity without reduction of antitumour efficacy or the production of new toxicities has therefore been a long-time therapeutic goal. It has now been largely achieved by prior administration of dexrazoxane (DXRz; Cardioxane in Europe; Zinecard in North America; ICRF 187). Six randomized, controlled clinical trials in breast and lung cancer and in soft tissue sarcomas of children have shown a 90% reduction in doxorubicin-induced cardiotoxicity. The results of all these trials lead to the conclusion that DXRz permits: (1) cardiotoxic doses of doxorubicin to be given without cardiotoxicity; (2) patients with increased cardiac risk factors to be treated with full doses of dioxorubicin; (3) second-line treatment with other cardiotoxic drugs.

Development of the model of rat isolated perfused heart for the evaluation of anthracycline cardiotoxicity and its circumvention

1. In order to develop a predictive model for the preclinical evaluation of anthracycline cardiotoxicity and the means of preventing it, we have studied the functional parameters of perfused hearts isolated from rats receiving repeated doses of several anthracyclines. 2. The anthracyclines studied were doxorubicin, epirubicin, pirarubicin and daunorubicin, and we also studied a liposomal formulation of daunorubicin (DaunoXome) and the co-administration of dexrazoxane (ICRF-187) and doxorubicin. 3. Anthracyclines were administered i.p. at equimolar doses corresponding to 3 mg kg-1 per injection of doxorubicin, every other day for a total of six doses. Dexrazoxane was used at the dose of 30 mg kg-1 per injection and was administered either 30 min before or 30 min after doxorubicin. We evaluated any general toxicity towards the animals as well as alterations of left ventricular contractility and relaxation ex vivo. 4. Epirubicin and daunorubicin were significantly less cardiotoxic than doxorubicin, and neither pirarubicin nor DaunoXome caused significant alterations in cardiac function. There was a direct relationship between the decrease in cardiac contractility or relaxation and anthracycline accumulation in the heart, evaluated after the same treatment schedule. 5. Dexrazoxane induced a significant protection against doxorubicin-induced cardiac toxicity when administered 30 min before doxorubicin, whereas this protection was ineffective when administered 30 min after doxorubicin. Direct perfusion of DaunoXome in isolated hearts of untreated animals resulted in a 12-fold reduction of the accumulation of daunorubicin in heart tissue as compared to the perfusion of free daunorubicin, and did not cause alterations in cardiac function at a dosage for which free daunorubicin induced major alterations. 6. The isolated perfused rat heart appears to be a valuable model for screening of new anthracyclines and of strategies for circumventing anthracycline cardiotoxicity.

Doxorubicin-heparin complex: reduction of cardiotoxicity of doxorubicin

We have compared the antitumor activity and cardiotoxicity of free doxorubicin (Dox) and doxorubicin-heparin complex in vivo and in vitro. Dox and Dox-heparin complex equally inhibited the DNA synthesis of leukemic cells and showed a similar anticancer activity against tumor-bearing mice. Acute toxicity of Dox at the dose of 20 mg/kg or 30 mg/kg was significantly more profound than that of the Dox-heparin complex, which was demonstrated by survival rate (P < 0.01). Chronic toxicities of Dox and the Dox-heparin complex were compared by giving the respective reagent (2 mg/kg) weekly for 20 weeks. The weight gains of the mice given Dox-heparin complex were greater than those of the mice given Dox alone (P < 0.01). The pathological damage to the cardiac tissue in mice treated with Dox-heparin complex was significantly less severe than that of mice treated with Dox. Thus, the present study indicates that complexing with heparin diminished the acute and chronic toxicity of Dox without reducing its antitumor activity in mice, and suggests a possible clinical application of Dox-heparin complex in humans.

Cardioprotection with ICRF-187 (Cardioxane) in patients with advanced breast cancer having cardiac risk factors for doxorubicin cardiotoxicity, treated with the FDC regimen

A study of cardioprotection with ICRF-187 (Cardioxane, Eurocetus) has been performed in 35 patients with metastatic breast cancer treated with the FDC regimen (5-fluorouracil 500 mg/m2 i.v., day 1; doxorubicin 50 mg/m2 i.v., day 1; cyclophosphamide 500 mg/m2 i.v., day 1). All patients had one or more cardiac risk factors for doxorubicin cardiotoxicity including 24 who had previously received left-chest-wall irradiation. Cardioxane was applied at a dosage of 1000 mg/m2 as a 15-min infusion in Ringer lactate solution 30 min before doxorubicin administration. Cardiological monitoring included left-ventricular ejection fraction (LVEF) determination by echocardiography before treatment and before each cycle following the cumulative doxorubicin dose of 200 mg/m2. Of the 35 patients, 34 were evaluable fore response, and the overall response rate was 19/34 (56%) with 3/34 complete responses and 16/34 partial responses. Statistical analysis of LVEF values in relation to increasing cumulative doxorubicin doses with Wilcoxon's test of equivalent pairs and Friedman's test has demonstrated that no cardiotoxicity was detected up to a cumulative doxorubicin dose of between 800 mg/m2 and 1000 mg/m2, except for 2 patients in whom a decrease of 20% in relation to the LVEF pretreatment level was demonstrated following a cumulative drug dose of 250 mg/m2. Thus Cardioxane provides an effective cardioprotection even in breast cancer patients with cardiac risk factors for doxorubicin cardiotoxicity treated with the FDC regimen.