Credit: USDA
VIENNA—Encapsulating the anthracycline doxorubicin in a liposome can reduce the risk of developing heart damage, according to a study presented at EuroEcho-Imaging 2014.
Researchers administered doxorubicin encased in a liposome to a small group of pigs and compared cardiac outcomes to those in pigs that received unmanipulated doxorubicin or epirubicin.
Pigs that received encapsulated doxorubicin still developed cardiotoxicity, but at lower rates than pigs that received traditional doxorubicin.
Pigs that received epirubicin were excluded due to low survival rates.
“[M]any chemotherapies—in particular, anthracyclines—cause cardiac side effects that can lead to cardiomyopathy and severe heart failure,” said study investigator Jutta Bergler-Klein, MD, of the Medical University of Vienna in Austria. “Cardiotoxicity can occur acutely or up to 30 years after chemotherapy and is the second most common cause of death in cancer patients, after secondary malignancy in childhood cancer survivors.”
“Liposomal encapsulation is a new technique which wraps the chemotherapy drug in a fatty cover called a liposome. More of the drug reaches the cancer cells because there is less degradation, and there are fewer side effects on healthy cells because the fat cover acts as a barrier.”
“The drug stays in the bloodstream longer, allowing higher cumulative doses to be given. We tested whether non-pegylated liposome encapsulation of the anthracycline doxorubicin (called Myocet) could decrease its cardiotoxicity compared to conventional doxorubicin or epirubicin, another anthracycline.”
The study included 24 pigs that were randomized to receive the human dose-equivalent of Myocet, conventional doxorubicin, or epirubicin in 3 cycles. The epirubicin group was excluded from the final analyses because of low survival levels.
The researchers assessed cardiac function by echocardiography and MRI at baseline and follow-up (after about 3 months). Laboratory follow-up included hematology, renal function, and measurement of the cardiac enzymes troponin and BNP.
“The dose, imaging methodology, and blood parameters simulate the monitoring that patients on this treatment would receive and produces valuable translational data,” Dr Bergler-Klein said.
The researchers found that the group receiving Myocet had better diastolic and systolic function in the left and right ventricles, compared to conventional doxorubicin. The Myocet group also had less fibrosis in the myocardium, as shown by MRI and histology staining.
“Our study shows that doxorubicin encapsulated in a liposome had fewer cardiac side effects than doxorubicin given in the conventional way,” Dr Bergler-Klein said.
“We did find cardiac toxicity in the Myocet group as well, despite the fact that the pigs were young, healthy, and received anthracyclines for only a short period. This emphasizes how important it is for all cancer patients taking anthracyclines to receive cardiac monitoring using echocardiography and biomarkers, and MRI where indicated.”
“Many patients who recover after chemotherapy have asymptomatic heart damage, which can become symptomatic as they get older. When heart problems are picked up early, patients can be given preventive treatment, including ACE inhibitors, angiotensin receptor blockers, or beta-blockers, to prevent the progression to overt heart failure.”
The researchers are now conducting gene-expression profiling on the histology samples, hoping to explain the better outcome and cardiac function after Myocet therapy. They have found differences in the expression of genes that control energy use and the metabolic state, with better regulation in the Myocet group.
