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Model systems for cardiotoxic effects of anthracyclines
Abstract:
The use of anthracycline antibiotics in cancer chemotherapy is limited by their cardiotoxic qualities. For the evaluation of new derivatives animal model systems are required. Cardiomyopathy can be induced in rabbits and monkeys, but these models are too expensive for screening purposes. In rats, anthracycline antibiotics cause morphologic lesions of the heart muscle, but these are more difficult to demonstrate than in larger animals. However, significant changes of the heart function (electrocardiogram (ECG), cardiac output), the function of heart mitochondria (inhibition of electron transfer, uncoupling of oxidative phosphorylation and inhibition of Ca translocation) occur in a dose-related manner. Intraventricular conduction defect demonstrated in the ECG is one of the earliest and most consistent expressions of the cardiotoxic properties of anthracyclines. It was therefore used as primary screening parameter. The results of the screening of over 50 new anthracyclines has shown that the cardiotoxic properties vary considerably and that they are not closely related to the chemotherapeutic and the hematotoxic properties. Interesting structure-activity relationships were observed in a series of rubidazone derivatives substituted at the benzhydrazone part of the molecule.
Insights
Anthracycline antibiotics used in cancer therapy can harm the heart. Researchers screened over 50 new anthracyclines in rats, finding varying cardiotoxic effects not linked to anticancer or blood toxicity.
Area of Science:
- Pharmacology
- Cardiology
- Oncology
Background:
- Anthracycline antibiotics are vital cancer chemotherapeutics but exhibit dose-limiting cardiotoxicity.
- Existing animal models (rabbits, monkeys) for evaluating anthracycline cardiotoxicity are costly.
- Rats offer a viable model for assessing anthracycline cardiotoxicity, despite challenges in visualizing morphologic lesions.
Purpose of the Study:
- To establish and utilize a rat model for screening the cardiotoxic potential of novel anthracycline derivatives.
- To identify structure-activity relationships among anthracycline derivatives concerning cardiotoxicity.
Main Methods:
- Induction of cardiotoxicity in rats using anthracycline antibiotics.
- Monitoring of cardiac function via electrocardiogram (ECG) and cardiac output measurements.
- Assessment of mitochondrial function, including electron transfer, oxidative phosphorylation, and calcium translocation.
- Utilizing intraventricular conduction defects on ECG as a primary screening parameter for cardiotoxicity.
Main Results:
- Anthracycline administration in rats induced dose-dependent morphologic and functional cardiac changes.
- ECG-detected intraventricular conduction defects served as an early and consistent marker of anthracycline cardiotoxicity.
- Screening of over 50 novel anthracyclines revealed significant variability in cardiotoxic properties.
- Cardiotoxicity did not strongly correlate with chemotherapeutic efficacy or hematotoxicity.
- Specific structure-activity relationships were noted within a series of rubidazone derivatives.
Conclusions:
- The rat model effectively screens anthracycline cardiotoxicity, with ECG changes being a reliable indicator.
- Novel anthracycline derivatives exhibit diverse cardiotoxic profiles, independent of their primary therapeutic or hematotoxic effects.
- This research facilitates the development of safer anthracycline-based cancer therapies by identifying less cardiotoxic compounds.