Efficacy of Dexrazoxane in Cardiac Protection in Pediatric Patients Treated With Anthracyclines

Drug Selection and Posology, Optimal Therapies and Risk/Benefit Assessment in Medicine: The Paradigm of Iron-Chelating Drugs

The design of clinical protocols and the selection of drugs with appropriate posology are critical parameters for therapeutic outcomes. Optimal therapeutic protocols could ideally be designed in all diseases including for millions of patients affected by excess iron deposition (EID) toxicity based on personalised medicine parameters, as well as many variations and limitations. EID is an adverse prognostic factor for all diseases and especially for millions of chronically red-blood-cell-transfused patients. Differences in iron chelation therapy posology cause disappointing results in neurodegenerative diseases at low doses, but lifesaving outcomes in thalassemia major (TM) when using higher doses. In particular, the transformation of TM from a fatal to a chronic disease has been achieved using effective doses of oral deferiprone (L1), which improved compliance and cleared excess toxic iron from the heart associated with increased mortality in TM. Furthermore, effective L1 and L1/deferoxamine combination posology resulted in the complete elimination of EID and the maintenance of normal iron store levels in TM. The selection of effective chelation protocols has been monitored by MRI T2* diagnosis for EID levels in different organs. Millions of other iron-loaded patients with sickle cell anemia, myelodysplasia and haemopoietic stem cell transplantation, or non-iron-loaded categories with EID in different organs could also benefit from such chelation therapy advances. Drawbacks of chelation therapy include drug toxicity in some patients and also the wide use of suboptimal chelation protocols, resulting in ineffective therapies. Drug metabolic effects, and interactions with other metals, drugs and dietary molecules also affected iron chelation therapy. Drug selection and the identification of effective or optimal dose protocols are essential for positive therapeutic outcomes in the use of chelating drugs in TM and other iron-loaded and non-iron-loaded conditions, as well as general iron toxicity.

Abnormal Global Longitudinal Strain During Anthracycline Treatment Predicts Future Cardiotoxicity in Children

Global longitudinal strain (GLS) is a sensitive predictor of cardiotoxicity in adults with cancer. However, the significance of abnormal GLS during childhood cancer treatment is less well-understood. The objective was to evaluate the use of GLS for predicting later cardiac dysfunction in pediatric cancer survivors exposed to high-dose anthracyclines. This was a retrospective study of pediatric patients exposed to a doxorubicin isotoxic equivalent dose of ≥ 225 mg/m2. Transthoracic echocardiograms (TTE) were obtained prior to chemotherapy (T1), during anthracycline therapy (T2), and following completion of therapy (T3). Cardiotoxicity was defined as meeting at least one of the following criteria after anthracycline therapy: a decrease in left ventricle ejection fraction (LVEF) by 10% from baseline to a value < 55%, fractional shortening < 28%, or a decrease in GLS by ≥ 15% from baseline. Nineteen of 57 (33%) patients met criteria for cardiotoxicity at T3. Cardiotoxicity was associated with a lower LVEF at T2 (p = 0.0003) and a decrease in GLS by ≥ 15% at T2 compared to baseline (p =  < 0.0001). ROC analysis revealed that the best predictor of cardiotoxicity at T3 was the percent change in GLS at T2 compared to baseline (AUC 0.87). A subgroup analysis revealed that a decrease in GLS by ≥ 15% from baseline at 0-6 months from completion of anthracycline therapy was associated with cardiotoxicity > 1-year post-treatment (p = 0.017). A decline in GLS during chemotherapy was the best predictor of cardiotoxicity post-treatment. GLS serves as an important marker of cardiac function in pediatric patients undergoing treatment with anthracyclines.

Iron Load Toxicity in Medicine: From Molecular and Cellular Aspects to Clinical Implications

Iron is essential for all organisms and cells. Diseases of iron imbalance affect billions of patients, including those with iron overload and other forms of iron toxicity. Excess iron load is an adverse prognostic factor for all diseases and can cause serious organ damage and fatalities following chronic red blood cell transfusions in patients of many conditions, including hemoglobinopathies, myelodyspasia, and hematopoietic stem cell transplantation. Similar toxicity of excess body iron load but at a slower rate of disease progression is found in idiopathic haemochromatosis patients. Excess iron deposition in different regions of the brain with suspected toxicity has been identified by MRI T2* and similar methods in many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Based on its role as the major biological catalyst of free radical reactions and the Fenton reaction, iron has also been implicated in all diseases associated with free radical pathology and tissue damage. Furthermore, the recent discovery of ferroptosis, which is a cell death program based on free radical generation by iron and cell membrane lipid oxidation, sparked thousands of investigations and the association of iron with cardiac, kidney, liver, and many other diseases, including cancer and infections. The toxicity implications of iron in a labile, non-protein bound form and its complexes with dietary molecules such as vitamin C and drugs such as doxorubicin and other xenobiotic molecules in relation to carcinogenesis and other forms of toxicity are also discussed. In each case and form of iron toxicity, the mechanistic insights, diagnostic criteria, and molecular interactions are essential for the design of new and effective therapeutic interventions and of future targeted therapeutic strategies. In particular, this approach has been successful for the treatment of most iron loading conditions and especially for the transition of thalassemia from a fatal to a chronic disease due to new therapeutic protocols resulting in the complete elimination of iron overload and of iron toxicity.