Defining Late Onset Occult Asymptomatic Cardiotoxicity in Childhood Cancer Survivors Exposed to Anthracycline Therapy: A Cardiac Magnetic Resonance and Biomarker Imaging and Serological Biomarker Study

Part A: Patients who received a high dose of anthracyclines and who completed chemotherapy for a minimum of 2 year and are still in remission we gathered information about their previous heart disease, radiation dose to the heart, bone marrow transplant, age at treatment, gender, elevation of serum cardiac troponin-T or N-terminal pro-brain natriuretic peptide measurements during anthracycline therapy, systolic dysfunction and congestive heart failure during anthracycline therapy. Participants had a Cardiac MRI (CMRI), echo and collection of serum for the the measurement of biomarkers of inflammation (C Reactive Protein (CRP), TNF-α, myocyte injury (Cardiac troponin (cTn), extracellular matrix remodeling, (Matrix Metalloproteinases (MMP), Tissue inhibitors of metalloproteinases (TIMPs), C terminal propeptide of type I procollagen (PICP), C terminal telopeptide of collagen type I (CITP), Bone Alkaline Phosphatase, apoptosis (Caspase-3 P17 peptide), and ventricular derived B-type natriuretic peptide (BNP) once during the study. Part A has been completed.

Part B: For those patients enrolled in part A they had another CMRI to validate CMRI findings and to study progression of cardiomyopathy overtime by comparing all CMRI derived imaging parameters between the first and second subject visits. Results of their standard of care echo will be post-processed to include the same parameters as the subjects' previous research echo that took place 2 years ago for comparison. Subjects had a blood draw (3mL) for for DNA and RNA analysis. Part B has been completed.

Part C: Will include an additional 60 patients who received low dose anthracycline therapy (<300 mg/m2) and who were also identified through the cardio-oncology registry. These patients will undergo a CMRI, study echo, and a blood sampling: Cardiac Troponin (cTn) , Matrix Metalloproteinases (MMP), Tissue inhibitors of metalloproteinases (TIMPs), C terminal propeptide of type I procollagen (PICP), C terminal telopeptide of collagen type I (CITP), Bone Alkaline Phosphatase, Caspase, C Reactive Protein (CRP), TNF-α, hematocrit, and NT-proBNP (a more sensitive measurement of BNP). Blood draw for DNA/microRNA analysis. Results of the standard of care echo will be post-processed to include the same parameters as the original 60 subjects' previous research echocardiogram for comparison purposes. All subjects recruited will serve either as a "case" (because they have cardiotoxicity) or as a control, if they are free of cardiotoxicity. Currently enrolling for part C patients who received low dose anthracyclines.

Cardiotoxicity for the overall group will be defined as global systolic dysfunction (indicated by an ejection fraction < 2SD below normal (Z score <-2), or decrease in global circumferential or longitudinal strain magnitude less than 2SD below normal. CMRI is considered to be the standard of care for assessment of cardiomyopathy. Based on the proven utility of CMRI as a screening tool for cardiomyopathy, CMRI studies will be performed as standard of care for assessment of global and regional myocardial function in cancer survivors. T1 pulse sequences for estimation of native T1 and ECV are continually being developed and refined, and will require further validation prior to clinical application. These sequences will still be considered be part of research.

STATISTICAL ANALYSIS Part A. CMRI parameters will be correlated with echo parameters of systolic and diastolic function. Data on peak circumferential strain will be compared to published historic normative data. T1 relaxation values will be compared to a group of age matched controls with normal SF and no exposure to anthracyclines. Results are expressed as mean and SD for continuous data and as percentages and numbers for categorical data. Subjects will be classified into 3 groups as detailed previously. Differences in the means between the groups and between exposed and controls for all normally distributed data will be assessed by analysis of variance. For skewed data, the Mann-Whitney U test will be performed. Image quality scores for all patients will be averaged for corresponding T1 maps. Mean segmental T1 and ventricular myocardial peak circumferential strain values and standard deviations will be calculated. The literature shows that T1 value is subject to a mild systematic heart rate dependency and a patient's height and weight has some impact on T1 values. To find and correct for these potential confounding factors, the relationships between T1 and heart rate, height, and weight will be investigated by using linear regression analysis of section data. In addition, the relationship between T1 mapping-derived relaxation time, left ventricular myocardial peak circumference strain and echocardiography parameters of systolic and diastolic function will be investigated by using linear regression analysis of section data. All statistical analysis will be performed with SAS 9.2. All tests are two tailed, and P < .05 is considered to indicate a significant difference. Interobserver and intraobserver variability of HARP strain will be performed using a paired t test and reported as a mean difference and 95% confidence interval.