Myocardial iron overload in transfusion-dependent pediatric patients with acute leukemia

Transfusion-related Iron Overload in Children With Leukemia

BACKGROUND

Children with leukemia commonly receive red blood cell (RBC) transfusions and transfusion-related iron overload (TRIO) is a major complication. However, few studies have evaluated TRIO in children with leukemia and no guidelines for screening exist. This retrospective, observational cohort study in children with acute leukemia evaluates the prevalence of TRIO and its impact on end-organ function.

RESULTS

The study included 139 patients; 60% standard-risk acute lymphoblastic leukemia (ALL), 32% high-risk (HR) ALL, and 9% acute myeloid leukemia (AML). The mean age at diagnosis was 6 years (range: 5 mo to 18 y). Patients with HR-ALL and AML were more likely to be transfused with ≥10 RBC units (59% and 92%, respectively) compared with those with standard-risk ALL (18%) (P<0.0001). Ferritin levels were measured in 68% patients and elevated (>1000 mcg/L) in 23%. Endocrinopathies were the most common end-organ abnormality. Hepatic dysfunction was significantly higher in patients with ≥10 RBC units transfused compared with those with <10 units (P=0.008).

CONCLUSIONS

Although the RBC transfusion burden is highest in patients with AML and HR-ALL, TRIO screening was not commonly performed. Patients who receive ≥10 RBC units are at risk for hepatic and endocrine dysfunction. We recommend routine screening for TRIO in children with leukemia, who are at risk for a higher transfusion burden.

The Impact of Iron Overload in Acute Leukemia: Chronic Inflammation, But Not the Presence of Nontransferrin Bound Iron is a Determinant of Oxidative Stress

In the literature, studies on the oxidant effects of nontransferrin bound iron [NTBI (eLPI assay)] during chemotherapy of acute lymphoblastic leukemia and acute myeloblastic leukemia are lacking. We established NTBI and oxidative stress determinants (OSD), iron parameters, high-sensitive C-reactive protein (hs-CRP) levels, liver tests, cumulative chemotherapeutic doses, and transfused blood in 36 children with acute leukemia throughout chemotherapy. These parameters were determined at the beginning and end of chemotherapy blocks (11 time points) and in 20 healthy children using enzyme-linked immunosorbent assay, and colorimetric and fluorometric enzymatic methods. In acute lymphoblastic leukemia, NTBI, OSD, and hs-CRP were higher than controls at 4/11, 7/11, and 9/11 time points (P<0.05). At 3 time points, NTBI and OSD concurrently increased. Ferritin, soluble transferrin receptor, serum iron, and transferrin saturation were higher than in controls at 5 to 11/11 time points (P<0.05). Those with NTBI had higher iron parameters than those without NTBI (P<0.05), but showed similar OSD, hs-CRP, liver enzymes, cumulative chemotherapeutics, and transfused blood (P>0.05). OSD did not correlate with NTBI, but correlated with hs-CRP. In conclusion, NTBI is a poor predictor of OSD in acute leukemia possibly because of the heterogeneity of NTBI and chronic inflammation. Further studies are needed to delineate the pathophysiology of these diseases.

Iron Overload in Survivors of Childhood Cancer

Iron overload is a significant cause of morbidity and mortality for patients who require frequent transfusions. We completed a prospective, cross-sectional study to evaluate the prevalence of iron overload in previously transfused childhood cancer survivors. Survivors recruited from the University of Minnesota Long-Term Follow-Up Clinic were stratified into 3 groups: oncology patients not treated with hematopoietic stem cell transplantation (HSCT) (n=27), patients treated with allogeneic HSCT (n=27), and patients treated with autologous HSCT (n=9). Serum ferritin was collected and hepatic magnetic resonance imaging (FerriScan) was obtained for those with iron overload (defined as ferritin ≥1000 ng/mL). The prevalence of iron overload in subjects with a history of allogeneic HSCT was 25.9% (95% CI, 9.4%-42.5%) compared with only 3.7% (95% CI, 0%-10.8%) in subjects treated without HSCT and 0% in subjects treated with autologous HSCT. No association was found between serum ferritin levels and the presence of cardiac, liver, or endocrine dysfunction. The prevalence of iron overload in subjects who received no HSCT or autologous HSCT is low in our study. A higher prevalence was found in patients receiving allogeneic HSCT, reiterating the importance of screening these patients for iron overload in accordance with the current Children's Oncology Group Long Term Follow-Up Guidelines.

Early Cardiac Iron Overload in a Child on Treatment of Acute Lymphoblastic Leukemia

An 11-year-old boy with Down syndrome and acute lymphoblastic leukemia developed hepatic dysfunction after only 10 months of treatment. MRI revealed severe iron deposition in the liver, pancreas, and heart. In stark contrast to what is seen in hemoglobinopathies, pancreatic and cardiac iron overload occurred with relatively low transfusion exposure and in a very short time period in this patient. Although extensive experience managing iron overload in hemoglobinopathies informs our approach in other diseases, it is clear that factors not present in hemoglobinopathies may be operative in patients with malignancy undergoing intense chemotherapy that lead to high levels of free iron and rapid loading of the heart and endocrine organs.

An assessment of iron overload in children treated for cancer and nonmalignant hematologic disorders

Our goal was to assess the natural fate of iron overload (IO) following transfusions of packed red blood cells (PRBCs) in children treated for cancer and nonmalignant disorders according to the intensity level of their treatment. Sixty-six children were followed up from February 2010 to March 2013. The transfusion burden was compared between three treatment intensity groups assigned according to the Intensity of Treatment Rating Scale 3.0 (ITR-3). IO was assessed by serial measurements of serum ferritin (SF) (n= 66) and quantification of tissue iron by magnetic resonance imaging (MRI) (n=12). Of the children studied, 36 % (24/66) received moderately intensive treatment (level 2), 21 % (14/ 66) received very intensive treatment (level 3), and 42 % (28/ 66) received the most intensive treatment (level 4). The number of PRBC (p=0.016), the total transfused volume (p= 0.026), and transfused volume adjusted to body weight (p= 0.004) were significantly higher in the level 4 group. By the median follow-up time of 35.5 months (range 8–133), 21– 29 % of patients (including level 2 and level 3 children) had SF >1,000 μg/l 1 year after cessation of transfusions. The slowest decrease of SF was observed in the level 4 group. Initial MRI examination demonstrated either mild or moderate IO in the liver and spleen. Repetitive MRI showed significant improvement in relaxation time between the initial and follow-up MRI performances in the liver (5.9 vs. 8.6 ms, p= 0.03) and the spleen (4.3 vs. 8.8 ms, p=0.03).

CONCLUSION

IO diminished over time, but in the level 4 patients, it was detectable for years after cessation of transfusions.

Characterization of transfusion-derived iron deposition in childhood cancer survivors

BACKGROUND

Childhood cancer survivors (CCS) receiving packed red blood cell (PRBC) transfusions may have increased risk for vital organ iron deposition causing serious late effects.

METHODS

This cross-sectional cohort study of a CCS cohort quantified organ iron content by magnetic resonance imaging. Iron status by serum markers and hemochromatosis gene mutation status were assessed.

RESULTS

Seventy-five patients who had received a range (0-392 mL/kg) of cumulative PRBC transfusion volumes were enrolled (median age 14 years, range 8-25.6 years at evaluation). Median follow-up time was 4.4 years, and median time since last transfusion was 4.9 years. Cancer diagnoses included acute lymphoblastic or myelogenous leukemia (ALL/AML; n = 33) and solid tumors (n = 42). Liver and pancreatic iron concentrations were elevated in 36 of 73 (49.3%) and 19 of 72 (26.4%) subjects, respectively. Cardiac iron concentration was not increased in this cohort. In multivariate analysis, cumulative PRBC volume (P < 0.0001) and older age at diagnosis (P < 0.0001) predicted elevated liver iron concentration.

CONCLUSIONS

Iron overload (IO) may occur in children and adolescents/young adults treated for cancer and is associated with cumulative PRBC transfusion volume and age at diagnosis.

IMPACT

These findings have implications for development of monitoring and management guidelines for cancer patients and survivors at risk for IO, exploration of the additive risk of liver/pancreatic damage from chemotherapeutic exposures, and health education to minimize further liver/pancreatic damage from exposures such as excessive alcohol intake and hepatotoxic medications.

Impact of hemochromatosis gene mutations on cardiac status in doxorubicin-treated survivors of childhood high-risk leukemia

BACKGROUND

Doxorubicin is associated with progressive cardiac dysfunction, possibly through the formation of doxorubicin-iron complexes leading to free-radical injury. The authors determined the frequency of hemochromatosis (HFE) gene mutations associated with hereditary hemochromatosis and their relationship with doxorubicin-associated cardiotoxicity in survivors of childhood high-risk acute lymphoblastic leukemia.

METHODS

Peripheral blood was tested for 2 common HFE allelic variants: C282Y and H63D. Serum cardiac troponin-T (cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP), which are biomarkers of cardiac injury and cardiomyopathy, respectively, were assayed during therapy. Left ventricular (LV) structure and function were assessed with echocardiography.

RESULTS

A total of 184 patients had DNA results for at least 1 variant, and 167 had DNA results for both: 24% carried H63D and 10% carried C282Y. Heterozygous C282Y genotype was associated with multiple elevations in cTnT concentrations (P = .039), but not NT-proBNP. At a median of 2.2 years (range, 1.0 years-3.6 years) after diagnosis, the mean Z-scores for LV fractional shortening (-0.71 [standard error (SE), 0.25]; P = .008), mass (-0.84 [SE, 0.17]; P < .001), and end-systolic (-4.36 [SE, 0.26], P < .001) and end-diastolic (-0.68 [SE, 0.25]; P = .01) posterior wall thickness were found to be abnormal in children with either allele (n = 32). Noncarriers (n = 63) also were found to have below-normal LV mass (-0.45 [SE, 0.15]; P = .006) and end-systolic posterior wall thickness (-4.06 [SE, 0.17]; P < .001). Later follow-up demonstrated similar results.

CONCLUSIONS

Doxorubicin-associated myocardial injury was associated with C282Y HFE carriers. Although LV mass and wall thickness were found to be abnormally low overall, they were even lower in HFE carriers, who also had reduced LV function. Screening newly diagnosed cancer patients for HFE mutations may identify those at risk for doxorubicin-induced cardiotoxicity.

Association of projected transfusional iron burden with treatment intensity in childhood cancer survivors

BACKGROUND

Packed red blood cell (PRBC) transfusion is a mainstay in childhood cancer treatment, but has potential for inducing iron overload. The purpose of this study was to determine whether treatment intensity is predictive of projected iron burden resulting from PRBC transfusions among survivors of several forms of childhood cancer.

PROCEDURE

This retrospective cohort study involved patients treated at Children's Hospital Los Angeles (CHLA) between June 1, 2004 and December 31, 2009. Clinical/demographic data were abstracted from medical records. Treatment Intensity Level was determined for each patient using a published scale. Adjusted cumulative PRBC transfusion volume for each patient (ml/kg) was used to compute the adjusted total iron burden (mg/kg) based upon the average hematocrit of the product.

RESULTS

Median age of the cohort (n = 214) was 7.9 years (range 0.2-20.2). One hundred and fourteen (53.3%) were male and 129 (60.3%) were Hispanic/Latino. Diagnoses included acute leukemia and six solid tumors, management of which represents a range of cancer treatment intensities. The number of transfusions, transfusion volumes, and projected iron burden were significantly increased and exceeded upper limits of normal among patients with higher treatment intensity. Multivariate analysis found younger age and lower hemoglobin at diagnosis to be associated with greater iron burden after adjusting for treatment intensity.

CONCLUSION

Greater treatment intensity is associated with need for more PRBC transfusions, and thus increased risk of iron overload among childhood cancer survivors. Iron overload may represent another clinically significant late effect following childhood cancer treatment.

Therapeutic complications in a patient with high-risk acute lymphoblastic leukemia and undiagnosed hereditary hemochromatosis

Hereditary hemochromatosis (HH) is an autosomal-recessive disorder of iron metabolism that most commonly manifests in the fourth or fifth decade of life. Here, we describe a 14-year-old male who presented with high-risk acute lymphoblastic leukemia and previously undiagnosed HH. His treatment course was remarkable for significant therapeutic complications, including iron overload, hepatic failure, cardiac dysfunction, and death. Postmortem testing revealed homozygosity for the C282Y mutation, confirming the diagnosis of HH. Since HH mutations occur commonly in select populations, screening patients with leukemia for HH may better inform treatment decisions regarding chemotherapy, transfusions, and/or iron chelation therapy.

Insidious iron burden in pediatric patients with acute lymphoblastic leukemia

BACKGROUND

A significant iron burden may occur after only 10 blood transfusions in patients with hematologic disorders. Children with acute lymphoblastic leukemia (ALL) routinely receive blood transfusions during therapy, although few studies to date have quantified transfusion-related iron burden in these patients. This study quantifies the transfused blood volume and resultant iron load in a large cohort of pediatric patients with ALL, and evaluates risk factors that may impact transfusion volume.

METHODS

This single institution retrospective study evaluated 107 patients who completed therapy for ALL between July 1995 and March 2007. Age, weight, and hemoglobin at presentation, ALL risk category, leukemia cell type, and volume of blood transfusions were collected from medical records.

RESULTS

Patients received an average of 115 ml/kg of blood (77 mg/kg iron) during treatment. There was a significant association between the volume of packed red blood cells and ALL risk category. Patients with standard-risk disease received 90 ml/kg (60 mg/kg iron), patients with high-risk disease 196 ml/kg (131 mg/kg iron) and patients with T-cell disease 114 ml/kg (76 mg/kg iron). There was no correlation between age or hemoglobin at presentation with amount of blood received.

CONCLUSIONS

Patients with ALL often receive a substantial amount of iron during therapy, with patients with high-risk disease receiving the greatest load. As iron overload has an overlapping toxicity profile with chemotherapy and is treatable, screening for increased iron burden and iron-related morbidities should be considered during long-term follow-up of patients with ALL, particularly in those with high-risk ALL.

Liver iron content determination by magnetic resonance imaging

Accurate evaluation of iron overload is necessary to establish the diagnosis of hemochromatosis and guide chelation treatment in transfusion-dependent anemia. The liver is the primary site for iron storage in patients with hemochromatosis or transfusion-dependent anemia, therefore, liver iron concentration (LIC) accurately reflects total body iron stores. In the past 20 years, magnetic resonance imaging (MRI) has emerged as a promising method for measuring LIC in a variety of diseases. We review the potential role of MRI in LIC determination in the most important disorders that are characterized by iron overload, that is, thalassemia major, other hemoglobinopathies, acquired anemia, and hemochromatosis. Most studies have been performed in thalassemia major and MRI is currently a widely accepted method for guiding chelation treatment in these patients. However, the lack of correlation between liver and cardiac iron stores suggests that both organs should be evaluated with MRI, since cardiac disease is the leading cause of death in this population. It is also unclear which MRI method is the most accurate since there are no large studies that have directly compared the different available techniques. The role of MRI in the era of genetic diagnosis of hemochromatosis is also debated, whereas data on the accuracy of the method in other hematological and liver diseases are rather limited. However, MRI is a fast, non-invasive and relatively accurate diagnostic tool for assessing LIC, and its use is expected to increase as the role of iron in the pathogenesis of liver disease becomes clearer.