Long-lasting effect of dexrazoxane against anthracycline cardiotoxicity in rats

Effect of doxorubicin on cardiac lipid metabolism-related transcriptome and the protective activity of Alda-1

The use of doxorubicin (DOX) as an antineoplastic drug is compromised by its cardiotoxicity risk. Although several mechanisms have been proposed for DOX-induced cardiac dysfunction, there is still increased interest in assessing its effects. Likewise, it is important to find protocols that can prevent or minimize the side effects of DOX without hindering its antitumor activity. Thus, this study was designed to investigate the molecular mechanisms underlying DOX cardiotoxicity, with a special focus on cardiac energy metabolism and the ability of Alda-1 (ALDH2 agonist) to prevent DOX-induced cardiac alterations. We explored the effects of DOX on the histological morphology of the myocardium, on lipid profile, and on the expression of genes related to fatty acid metabolism, in the presence and absence of Alda-1 (8 mg/kg body weight; b.wt.). Two DOX treatment protocols were used: a single dose of DOX (4 mg/kg b.wt.); four doses of DOX (4 mg/kg b.wt.), one dose/week, for 4 weeks. Treatment with DOX caused a progressive injury in the cardiac tissue and an increase in the blood total cholesterol, high-density lipoproteins, very low-density lipoproteins and triglyceride, as well as an up-regulation of FABP4 (DOX and DOX + Alda-1 groups) and Slc27a2 (in DOX-treated animals). Alda-1 administration promoted reduction in the severity of the histopathological injuries (after single dose of DOX) and Slc27a2 overexpression was restored. In conclusion, the study revealed novel insights regarding the development of DOX-mediated cardiomyopathy, indicating a relationship between DOX exposure and FABP4 and Slc27a2 overexpression, and confirmed the cardioprotective effect of Alda-1.

Nutrition Modulation of Cardiotoxicity and Anticancer Efficacy Related to Doxorubicin Chemotherapy by Glutamine and ω-3 Polyunsaturated Fatty Acids

BACKGROUND

Doxorubicin (DOX) has been one of the most effective antitumor agents against a broad spectrum of malignancies. However, DOX-induced cardiotoxicity forms the major cumulative dose-limiting factor. Glutamine and ω-3 polyunsaturated fatty acids (PUFAs) are putatively cardioprotective during various stresses and/or have potential chemosensitizing effects during cancer chemotherapy.

METHODS

Antitumor activity and cardiotoxicity of DOX treatment were evaluated simultaneously in a MatBIII mammary adenocarcinoma tumor-bearing rat model treated with DOX (cumulative dose 12 mg/kg). Single or combined treatment of parenteral glutamine (0.35 g/kg) and ω-3 PUFAs (0.19 g/kg eicosapentaenoic acid and 0.18 g/kg docosahexaenoic acid) was administered every other day, starting 6 days before chemotherapy initiation until the end of study (day 50).

RESULTS

Glutamine alone significantly prevented DOX-related deterioration of cardiac function, reduced serum cardiac troponin I levels, and diminished cardiac lipid peroxidation while not affecting tumor inhibition kinetics. Single ω-3 PUFA treatment significantly enhanced antitumor activity of DOX associated with intensified tumoral oxidative stress and enhanced tumoral DOX concentration while not potentiating cardiac dysfunction or increasing cardiac oxidative stress. Intriguingly, providing glutamine and ω-3 PUFAs together did not consistently confer a greater benefit; conversely, individual benefits on cardiotoxicity and chemosensitization were mostly attenuated or completely lost when combined.

CONCLUSIONS

Our data demonstrate an interesting differentiality or even dichotomy in the response of tumor and host to single parenteral glutamine and ω-3 PUFA treatments. The intriguing glutamine × ω-3 PUFA interaction observed draws into question the common assumption that there are additive benefits of combinations of nutrients that are beneficial on an individual basis.

Differential analysis of transient increases of serum cTnI in response to handling in rats

Serum cardiac troponins are the key biomarkers of myocardial necrosis in humans and in preclinical species. The use of ultrasensitive assays for serum cardiac troponin I (cTnI) as a biomarker in safety studies is hampered by interindividual differences. In this study, we investigated the effect of handling procedures on serum cTnI and explored modeling and simulation approaches to mitigate the impact of these interindividual differences. Femoral-catheterized male Crl:WI(Han) rats (n = 16/group) were left undisturbed in their cages with no handling; subjected to 5 min of isoflurane/O₂ anesthesia (A); or placed into a rodent restrainer followed by simulated tail vein injection (RR). Serum cTnI concentrations were assessed over a 24-h period using an ultrasensitive assay, and the study was repeated for confirmation. The mean serum cTnI concentration pre-procedure was 4.2 pg/mL, and remained stable throughout the duration of the study in the rats submitted to the A procedure. Serum cTnI concentrations increased transiently after the RR procedure with a median time to maximum concentration (T_max), of 1 and 2 h and a mean maximum value concentration (C_max), of 53.0 and 7.2 pg/mL in the initial and repeat studies, respectively. A population pharmacodynamic model identified interindividual, procedure- and study-specific effects on serum cTnI concentrations in rats. It is concluded that a modeling and simulation approach more appropriately describes and statistically analyzes the data obtained with this ultrasensitive assays.

A low dose of doxorubicin improves antioxidant defence system and modulates anaerobic metabolism during the development of lymphoma

Objective:

The objective of the present study is to find low dose of doxorubicin (DOX) with cancer preventive activity and to check the implication of this low dose of DOX on antioxidant defence system during lymphoma growth in mice, as the clinical utility of anthracycline anticancer drugs, especially DOX is limited by a progressive cardiotoxicity linked to mitochondrial damage.

Materials and Methods:

We selected a dose of DOX (0.90 mg/kg body weight of mouse), which is about 20 folds lower than clinically used dose for cancer treatment. The cancer preventive action is monitored by modulation of anaerobic metabolism. The effect of this dose on antioxidant defence system is analyzed by testing the activities of antioxidant enzymes, such as catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST). The activities of these enzymes were monitored at different intervals during the growth of lymphoma in mice.

Results:

The activities of antioxidant enzymes, such as CAT, SOD, and GST, were found to decrease gradually during the growth of lymphoma in mice. The anaerobic metabolism was increasing with lymphoma growth. We report that about 20 folds lower dose of DOX enhances the activities of antioxidant enzymes and decreases anaerobic metabolism during the development of lymphoma. These enzymes of antioxidant defence system suppress oxidative stress and mitochondrial damage, whereas a decrease in anaerobic metabolism checks cancer growth.

Conclusions:

The result suggests that dose cumulative cellular toxicity of DOX may be avoided by treating cancer in animals with lower doses of DOX in combination with other drugs.

Dexrazoxane shows cytoprotective effects in zoledronic acid-treated human cells in vitro and in the rabbit tibia model in vivo

INTRODUCTION

Bisphosphonates are important and effective drugs in oncology and osteoporosis therapy. They accumulate in the bone matrix becoming released and active by bone resorption. This leads to effective inhibition of tumor cells and bone degradation. A side effect of bisphosphonates similar to other drugs like denosumab is osteonecrosis of the jaws (ONJ). This problem mostly occurs after tooth extraction. We studied the cytoprotectant dexrazoxane known from anthracycline chemotherapy for cytoprotection in nitrogen-containing bisphosphonate treated cells and in the rabbit tibia model to evaluate a possible value in ONJ management.

MATERIALS & METHODS

Human osteoblasts (HOB) P2 cells and Human ginigiva fibroblasts (HGF) P2 cells were treated with zoledronic acid (50 μmol/L) and the cytoprotectant dexrazoxane (600 μmol/L). Analysis included cell viability testing with MTT assay and morphology analysis using CellTracker™ Green CMFDA. A biomaterial carrier (Bio-Oss Collagen) was implanted in the rabbit tibia of 6 female chinchilla bastard rabbits on both sides with drill hole defects (d: 3.2mm). Implants were loaded with 25 nmol zoledronic acid, with and without 300 nmol dexrazoxane and unloaded in a control group. Analysis included histological examination of undecalcified samples with toloudine blue staining after 10 days.

RESULTS

In vitro experiments showed a significantly higher MTT activity in cells treated with zoledronic acid together with dexrazoxane compared to the same cells treated with the bisphosphonate alone in t-test (HOB: p=0.0003; HGF: p below 0.0001) and one-way ANOVA. Cell morphology changes were consistent with these results. In vivo results showed newly formed bone trabeculae directly growing towards the implanted hydroxylapatite particles and cortical bone interface resorption activities in the control and the experimental group only.

CONCLUSION

The study suggests a possible value of this patented technology for ONJ therapy and prevention with local or systemic application.

Preclinical toxicity, toxicokinetics, and antitumoral efficacy studies of DTS-201, a tumor-selective peptidic prodrug of doxorubicin

PURPOSE

There is a clear clinical need for cytotoxic drugs with a lower systemic toxicity. DTS-201 (CPI-0004Na) is a peptidic prodrug of doxorubicin that shows an improved therapeutic index in experimental models. The purpose of the current study was to complete its preclinical characterization before initiation of phase I clinical trials.

EXPERIMENTAL DESIGN

The preclinical development program consisted of a detailed assessment of the general and cardiac toxicity profiles of DTS-201 in mice, rats, and dogs, together with mass balance and antitumoral efficacy studies in rodents. Neprilysin and thimet oligopeptidase expression, two enzymatic activators of DTS-201, was also characterized in human breast and prostate tumor biopsies.

RESULTS

The target organs of DTS-201 toxicity in rodents and dogs are typically those of doxorubicin, albeit at much higher doses. Importantly, chronic treatment with DTS-201 proved to be significantly less cardiotoxic than with doxorubicin at doses up to 8-fold higher in rats. The mass balance study showed that [14C] DTS-201 does not accumulate in the body after intravenous administration. The improved therapeutic index of DTS-201 compared with free doxorubicin was confirmed in three tumor xenograft models of prostate, breast, and lung cancer. Neprilysin and/or thimet oligopeptidase are expressed in all experimental human tumor types thus far tested as well as in a large majority of human breast and prostate tumor biopsies.

CONCLUSION

DTS-201 gave promising results in terms of general toxicity, cardiovascular tolerance, and in vivo efficacy in xenograft mouse models compared with free doxorubicin. Taken together, these results and the confirmation of the presence of activating enzymes in human tumor biopsies provide a strong rationale for a phase I clinical study in cancer patients.

Anthracycline-induced phospholipase A2 inhibition

The purpose of this essay is to overview our findings that membrane-associated calcium-independent phospholipase A2 is markedly inhibited by low, clinically relevant concentrations of anthracyclines. Our studies suggest that due to the essential role of this enzyme in membrane homeostasis, its inhibition can be one of the early culprits leading to anthracycline-induced cardiac dysfunction. The clinical importance and potential pharmaceutical use of this new phenomenon await further studies.

Dexrazoxane prevents doxorubicin-induced long-term cardiotoxicity and protects myocardial mitochondria from genetic and functional lesions in rats

BACKGROUND AND PURPOSE

Doxorubicin causes a chronic cardiomyopathy in which reactive oxygen species (ROS) accumulate over time and are associated with genetic and functional lesions of mitochondria. Dexrazoxane is a cardioprotective iron chelator that interferes with ROS production. We aim to analyze the effects of dexrazoxane on mitochondria in the prevention of doxorubicin-induced chronic myocardial lesions.

EXPERIMENTAL APPROACH

Wistar rats (11 weeks of age) were injected with intravenous doxorubicin (0.8 mg kg(-1) weekly for 7 weeks) with or without simultaneous dexrazoxane (8 mg kg(-1)). Animals were killed at 48 weeks. Cardiomyopathy was scored clinically and histologically and cardiac mitochondria were analyzed.

KEY RESULTS

Compared to control rats receiving saline, rats treated with doxorubicin alone developed a clinical, macroscopic, histological and ultrastructural cardiomyopathy with low cytochrome c-oxidase (COX) activity (26% of controls). The expression of the mtDNA-encoded COX II subunit was reduced (64% of controls). Myocardia exhibited a high production of ROS (malondialdehyde 338% and superoxide 787% of controls). Mitochondria were depleted of mitochondrial DNA (mtDNA copy number 46% of controls) and contained elevated levels of mtDNA deletions. Dexrazoxane co-administration prevented all these effects of doxorubicin on mitochondria, except that hearts co-exposed to doxorubicin and dexrazoxane had a slightly lower mtDNA content (81% of controls) and mtDNA deletions at low frequency.

CONCLUSIONS AND IMPLICATIONS

Dexrazoxane prevented doxorubicin induced late-onset cardiomyopathy and also protected the cardiac mitochondria from acquired ultrastructural, genetic and functional damage.

The 6-maleimidocaproyl hydrazone derivative of doxorubicin (DOXO-EMCH) is superior to free doxorubicin with respect to cardiotoxicity and mitochondrial damage

Doxorubicin causes a chronic cardiomyopathy in which genetic and functional lesions of mitochondria accumulate in the long-term and explain in part the delayed onset of heart dysfunction. DOXO-EMCH a 6-maleimidocaproyl hydrazone derivative of doxorubicin, is an albumin binding prodrug which has entered clinical trials because of its superior antitumor and toxicological profile. In the present work, we examined the chronic cardiotoxicity of DOXO-EMCH in direct comparison with doxorubicin. Rats (11 weeks of age) were treated with intravenous doxorubicin (0.8 mg/kg weekly for 7 weeks), an equimolar dose of DOXO-EMCH (1.1 mg/kg), or with 3.3 mg/kg of DOXO-EMCH. Controls received saline. Animals were euthanized at 48th week. Rats exposed to doxorubicin had a severe clinical, and histopathological cardiomyopathy with depressed myocardial activity of cytochrome c-oxidase (COX, 26% of controls), reduced expression of the mtDNA-encoded COX II subunit, decreased mtDNA copy numbers (46% of controls), and high levels of malondialdehyde and superoxide (787% of controls). All parameters were highly correlated with myocardial damage. Both DOXO-EMCH groups did not differ from controls with regard to clinical symptomatology, mortality and mitochondrial enzymes, although the myocardia of the high-dose group had slightly increased histopathological abnormalities, depressed mtDNA copies (74% of controls) and elevated superoxide levels (347% of controls). Doxorubicin-exposed hearts and to a lesser extent the myocardia of both DOXO-EMCH groups contained mtDNA-deletions. In summary both DOXO-EMCH doses were superior over doxorubicin with respect to clinical and histopathological evidence of cardiomyopathy, myocardial COX-activity, COX II expression, mtDNA-content, mtDNA mutation loads and superoxide production in rats.

Prevention of chronic anthracycline cardiotoxicity in the adult Fischer 344 rat by dexrazoxane and effects on iron metabolism

PURPOSE

Anthracyclines, such as doxorubicin and daunorubicin, continue to be widely used in the treatment of cancer, although they share the adverse effect of chronic, cumulative dose-related cardiotoxicity. The only approved treatment in prevention of anthracycline cardiotoxicity is dexrazoxane, a putative iron chelator. Previous in vitro studies have shown that disorders of iron metabolism, including altered IRP1-IRE binding, may be an important mechanism of anthracycline cardiotoxicity.

METHODS

This study examined the role of IRP1-IRE binding ex vivo in a chronic model of daunorubicin cardiotoxicity in the Fischer 344 rat and whether dexrazoxane could prevent any daunorubicin-induced changes in IRP1 binding. Young adult (5-6 months) Fischer 344 rats received daunorubicin (2.5 mg/kg iv once per week for 6 weeks) with and without pretreatment with dexrazoxane (50 mg/kg ip). Other groups received saline (controls) or dexrazoxane alone. Rats were killed either 4 h or 2 weeks after the last dose of daunorubicin to assess IRP1-IRE binding.

RESULTS

Contractility (dF/dt) of atrial tissue, obtained from rats 2 weeks after the last dose of daunorubicin, was significantly reduced in daunorubicin-treated compared to control rats. Dexrazoxane pretreatment protected against the daunorubicin-induced decrease in atrial dF/dt. However, left ventricular IRP1/IRE binding was not affected by daunorubicin treatment either 4 h or 2 weeks after the last dose of daunorubicin.

CONCLUSIONS

IRP1 binding may not be altered in the rat model of chronic anthracycline cardiotoxicity.

Changes in phospholipid content and myocardial calcium-independent phospholipase A2 activity during chronic anthracycline administration

Despite numerous investigations, the causes underlying anthracycline cardiomyopathy are yet to be established. We have recently reported that acute treatment with anthracyclines inhibits membrane-associated calcium-independent phospholipase A(2) (iPLA(2)) activity both in vitro and in vivo. This study presents data that iPLA(2) activity is also suppressed during chronic drug administration. Adult Sprague-Dawley rats were given weekly 1 mg/kg i.v. injections of doxorubicin for a total of 8 weeks. One week after the last injection, the animals were sacrificed, and heart tissue was assessed for phospholipid content and iPLA(2) activity. Membrane-associated iPLA(2) activity in the myocardium of doxorubicin-treated animals was 40% lower than that in control hearts. In addition, doxorubicin treatment resulted in significant alterations in the distribution of fatty acyl moieties esterified to the sn-2 position of choline glycerophospholipids. The ethanolamine species remained unaffected. Elevation in the amount of arachidonate and linoleate esterified to the sn-2 position of choline plasmalogens was consistent with the hypothesis that iPLA(2) displays selectivity for plasmalogen phospholipids; therefore, enzyme inhibition may affect hydrolysis of these phospholipid subclasses. Notably, the changes in phospholipid content occurred at a low cumulative dose of 8 mg/kg at which appearance of structural lesions was minimal. Therefore, these alterations seem to be both specific and early signs of cardiomyocyte pathology. The results support our hypothesis that myocardial iPLA(2) inhibition may be one of the steps that leads to the functional and structural changes associated with chronic anthracycline treatment.

Time-Dependent and Tissue-Specific Accumulation of mtDNA and Respiratory Chain Defects in Chronic Doxorubicin Cardiomyopathy

Background— Doxorubicin causes a chronic cardiomyopathy of unknown pathogenesis. We investigated whether acquired defects in mitochondrial DNA (mtDNA) and interconnected respiratory chain dysfunction may represent a molecular mechanism for its late onset.

Methods and Results— Rats were treated weekly with intravenous doxorubicin (1 mg/kg) for 7 weeks, starting at 11 weeks of age (group B). Controls received saline. Group C received doxorubicin identically to group B, but the course was started at 41 weeks of age. All rats were killed at week 48. Doxorubicin was also injected once, either 6 days (group D) or 2 hours (group E) before euthanasia. Heart and skeletal muscle were examined. Only group B rats developed a significant clinical, macroscopic, histological, and ultrastructural cardiomyopathy. Group B hearts had the lowest cytochrome c oxidase (COX) activity (24% of controls; P =0.003), the highest citrate synthase activity (135% of controls; P =0.005), and the highest production of superoxide. In group B, the respiratory subunit COXI, which is encoded by mtDNA, was reduced ( P <0.001), as was mtDNA (49% of controls, P <0.001). Group C hearts differed from group B in their lower cardiomyopathy score ( P =0.006), higher COX activity ( P =0.02), and higher mtDNA content ( P =0.04). Group B and to a lesser extent group C hearts contained deleted mtDNA. There was no detectable mitochondrial toxicity in group D and E hearts or in skeletal muscle.

Conclusions— In doxorubicin cardiomyopathy, mtDNA alterations, superoxide, and respiratory chain dysfunction accumulate long-term in the absence of the drug and are associated with a late onset.

Sino-atrial block during anesthesia in a patient with breast cancer being treated with the anticancer drug epirubicin

IMPLICATIONS

Epirubicin, an anticancer drug, causes cardiotoxicity. We reported a case of sino-atrial block during general anesthesia in a woman with breast cancer who had received epirubicin. Anesthesiologists should be aware of the possible occurrence of sino-atrial block with epirubicin, and planting a pacemaker might be considered even in asymptomatic patients.

Inhibition of cyclooxygenase-2 aggravates doxorubicin-mediated cardiac injury in vivo

The clinical use of doxorubicin, an anthracycline chemotherapeutic agent, is limited by cardiotoxicity, particularly when combined with herceptin, an antibody that blocks the HER2 receptor. Doxorubicin induces cyclooxygenase-2 (COX-2) activity in rat neonatal cardiomyocytes. This expression of COX-2 limits doxorubicin-induced cardiac cell injury, raising the possibility that the administration of a prostaglandin may protect the heart during the in vivo administration of doxorubicin. Doxorubicin (15 mg/kg) administered to adult male Sprague Dawley rats induced COX-2 expression and activity in cardiac tissue. Prostacyclin generation measured as the excretion of 2,3-dinor-6-keto-PGF(1alpha) also increased, and this was blocked by a COX-2 inhibitor, SC236. In contrast, administration of a COX-1 inhibitor SC560 at a dose that reduced serum thromboxane B2 by more than 80% did not prevent the doxorubicin-induced increase in prostacyclin generation. Doxorubicin increased cardiac injury, detected as a rise in plasma cardiac troponin T, serum lactate dehydrogenase, and cardiomyocyte apoptosis; this was aggravated by coadministration of SC236 but not SC560. The degree of injury in animals treated with a combination of doxorubicin and SC236 was attenuated by prior administration of the prostacyclin analogue iloprost. These data raise the possibility of protecting the heart during the administration of doxorubicin by prior administration of prostacyclin.

PNU-159548, a novel cytotoxic antitumor agent with a low cardiotoxic potential

PURPOSE

PNU-159548 (4-demethoxy-3'-deamino-3'aziridinyl-4'-methylsulphonyl-daunorubicin), a derivative of the anticancer idarubicin, has a broad spectrum of antitumoral activity in vitro and in vivo attributable to its DNA intercalating and alkylating properties. The present study was conducted to determine the cardiotoxic activity of PNU-159548 relative to doxorubicin in a chronic rat model sensitive to anthracycline-induced cardiomyopathy.

METHODS

Young adult male rats were allocated to the following treatment groups: group 1, PNU-159548 vehicle control (colloidal dispersion); group 2, doxorubicin control (saline); groups 3, 4, 5, 6, and 7, PNU-159548 at 0.12, 0.25, 0.50, 0.75, and 1.0 mg/kg, respectively; and group 8, 1.0 mg/kg doxorubicin. Treatments were administered intravenously once weekly for 4 weeks (first sacrifice time) or for 7 weeks (rats killed at weeks 8, 12, 22, 27, or 35). Body weights, organ weights, serum chemistry, hematology, serum troponin-T, and cardiac histopathology were followed throughout the study.

RESULTS

Doxorubicin caused irreversible cardiomyopathy evident at week 4 in some rats and progressing in severity in all rats by week 8. There were also marked myelotoxicity, increased liver and kidney weights, testicular atrophy, and about 20% mortality by week 27 in doxorubicin-treated rats. The deaths were attributed to cardiomyopathy and/or nephropathy. PNU-159548 caused a dose-dependent myelotoxicity, with the dose of 0.5 mg/kg per week being equimyelotoxic to 1.0 mg/kg per week doxorubicin. PNU-159548 also caused an increase in liver weight that was reversible and a non-reversible testicular atrophy but, unlike doxorubicin, had no effect on kidney weight. At equimyelotoxic doses, the cardiotoxicity caused by PNU-159548, expressed as the mean total score, was less than one-twentieth of that induced by doxorubicin, and much less than that predicted on the basis of its content of idarubicin, which is in turn markedly less cardiotoxic than doxorubicin.

CONCLUSIONS

The novel cytotoxic antitumor derivative, PNU-159548, is significantly less cardiotoxic than doxorubicin at equimyelosuppressive doses. The combination of intercalating and alkylating activities within the same molecule without the cardiotoxic side effects of anthracyclines makes PNU-159548 an excellent candidate for clinical development in oncology.