Serum Ferritin as Risk Factor for Veno-occlusive Disease of the Liver. Prospective Cohort Study

Efficacy and Safety of Iron Chelation Therapy After Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Thalassemia Patients: A Retrospective Observational Study

BACKGROUND

Studies on the increased body iron load in patients with thalassemia major have thoroughly demonstrated the problems caused by iron overload. In patients who undergo hematopoietic stem cell transplantation (HSCT) as curative therapy, iron overload continues long after transplantation. There are few pediatric studies on chelation therapy in the posttransplant period. In this study, we present the outcomes of our patients who received posttransplant oral chelation therapy.

PATIENTS AND METHODS

This retrospective observational study evaluated the outcomes of pediatric patients with thalassemia major who used oral chelation therapy after allogeneic HSCT at the Akdeniz University Pediatric Bone Marrow Unit between January 2008 and October 2019.

RESULTS

Deferasirox therapy was initiated in 58 pediatric patients who underwent HSCT for thalassemia. Pretreatment mean serum ferritin was 2166±1038 ng/mL. Treatment was initiated at a mean of 12±6.7 months after transplantation and continued for a mean of 15.7±11.5 months. At treatment discontinuation, the mean serum ferritin was 693±405 ng/mL and the mean reduction was -1472.75±1121.09 ng/mL (P<0.001 vs. posttreatment). Serum ferritin was below 500 ng/mL in 52% of the patients at treatment discontinuation. Manageable side effects such as nausea, vomiting, liver enzyme elevation, and proteinuria were observed in 17% of the patients, while one patient developed ototoxicity.

CONCLUSIONS

Deferasirox therapy effectively reduces iron overload in the posttransplant period. Studies evaluating the effects of early treatment on the graft may help to establish guidelines for posttransplant chelation therapy. Clear guidelines are needed regarding when to initiate and discontinue treatment.

Analysis of risk factors for hepatic sinusoidal obstruction syndrome following allogeneic hematopoietic stem cell transplantation in pediatric patients

Purpose

Hepatic sinusoidal obstruction syndrome (SOS) represents a serious complication following hematopoietic stem cell transplantation (HSCT). Our study aimed to investigate important risk factors of SOS in a pediatric population.

Methods

This retrospective study analyzed 105 children, adolescents and young adults who underwent allogeneic HSCT at our pediatric HSCT center in Jena. The observation period was 12 years and SOS was defined by the pediatric criteria of the European Society for Blood and Marrow Transplantation (EBMT).

Results

15 out of all 105 patients developed SOS (14.3%). The median time from HSCT to SOS diagnosis was 12 days. The mortality rate of SOS was 20.0%. In univariate analyses, we identified the significant risk factors of patient age < 1 year [odds ratio (OR) = 7.25, p = 0.037], prior treatment with gemtuzumab ozogamicin (OR = 11.00, p = 0.020), high pretransplant ferritin levels above 1500 ng/mL (OR = 4.00, p = 0.033), 2000 ng/mL (OR = 4.69, p = 0.016), and 2400 ng/mL (OR = 5.29, p = 0.005) as well as international normalized ratio (INR) ≥ 1.3 (OR = 5.91, p = 0.009). The following risk factors could be confirmed in multivariate analysis: treatment with gemtuzumab ozogamicin (OR = 9.24, p = 0.048), ferritin > 2400 ng/mL (OR = 5.74, p = 0.023), and INR ≥ 1.3 (OR = 8.02, p = 0.007).

Conclusion

Our study confirms several risk factors from the current literature. Additionally, this is the first report on the risk factor of high pretransplant INR.

Iron overload after allogeneic stem cell transplantation in children with acute lymphoblastic leukemia

Red blood cell transfusions are an essential part of supporting care in leukemia treatment. We examined the prevalence of iron overload and its effects on organ function and childhood growth in pediatric patients after allogeneic HSCT for acute lymphoblastic leukemia. Twenty-three patients were included (median age 12.6, range 7.5-21.4 years). Body iron load was determined using laboratory tests, hepatic and cardiac MRI, and by calculating iron received from transfusions. We performed multivariate analysis to determine association of body iron load with liver enzymes, cardiac function, insulin resistance, and growth. Median plasma ferritin was 344 (range 40-3235) ng/mL and exceeded 1000 ng/mL in three patients (13%). In MRI, 11 patients (48%) had hepatic iron overload and 1 patient (4%) myocardial iron overload. In cardiac MRI, 8 patients (35%) had significant but subclinical decrease in ejection fraction (median z-score -1.7, range -3.1-0.14), but cardiac function did not associate with iron status. Alanine transaminase associated with transfused iron per time unit (P = .001) after the median follow-up of 4.5 years. No correlation was found between iron load and growth or insulin resistance. Iron overload is common in children transplanted for ALL, but iron overload associated organ dysfunction is not present at early age. We recommend evaluation of iron load for all patients at least once during follow-up after transplantation.

Transjugular Intrahepatic Portosystemic Shunt for Very Severe Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS) after Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation with Post-transplantation Cyclophosphamide

Hepatic veno-occlusive disease or sinusoidal obstruction syndrome (VOD/SOS) is a threatening complication after both autologous and allogeneic hematopoietic stem cell transplantation (HSCT), with high mortality rates despite early medical treatment, including the use of defibrotide (DF). We retrospectively analyzed 185 unmanipulated haploidentical (haplo-) HSCT with post-transplantation cyclophosphamide as graft-versus-host disease prophylaxis performed consecutively between 2011 and June 2019 in a single center. Seventeen patients (9.2%) were diagnosed with VOD/SOS. Based on revised European Society for Blood and Marrow Transplantation severity criteria, the VOD/SOS cases were classified as mild in 2 patients (11.7%), moderate in 2 (11.7%), severe in 2 (11.7%), and very severe in 11 (64.9%). Thirteen patients (76%) were treated with DF, including all patients with severe or very severe VOD/SOS, except 1 patient with CNS hemorrhage. Sixteen patients (94%) were alive at day +100 after HSCT. Seven patients (41%) with very severe VOD/SOS were treated with transjugular intrahepatic portosystemic shunt (TIPS) owing to rapid clinical or analytical deterioration or refractory hepatorenal syndrome despite medical treatment, including DF. TIPS insertion was performed at a median time since VOD/SOS diagnosis of 4 days (range, 1 to 28 days) without technical complications in any case. The median hepatic venous pressure gradient before and after TIPS treatment was 24 mmHg (range, 14 to 29 mmHg) and 7 mmHg (range, 2 to 11 mmHg), respectively, with a median drop of 16 mmHg (range, 9 to 19 mmHg). Following TIPS insertion, all patients showed clinical improvement with hepatomegaly, ascites, and renal failure resolution, and all showed analytical improvement with reduced alanine aminotransferase (ALT), creatinine, and international normalized ratio values, except for patient 2, whose indication for TIPS was refractory hepatorenal syndrome with a normal ALT level. The 6 patients who had initiated DF before TIPS insertion completed 21 days of treatment. All patients met the criteria for complete remission (CR) at a median of 8 days after TIPS insertion (range, 2 to 82 days). The 100-day overall survival was 100%. For patients with rapid progressive VOD/SOS, early TIPS insertion allowed completion of DF therapy. The use of TIPS together with DF resulted in CR and no associated complications with no VOD/SOS-associated mortality despite high severity. In our experience, timely and individualized use of TIPS significantly improves outcomes of very severe VOD/SOS after haplo-HSCT. Therefore, TIPS should be promptly considered in rapidly progressive cases.

Reduced-intensity conditioning is effective for hematopoietic stem cell transplantation in young pediatric patients with Diamond-Blackfan anemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for the hematologic manifestations of Diamond-Blackfan anemia (DBA). However, data regarding the optimal conditioning regimen for DBA patients are limited. We retrospectively compared the outcomes of DBA patients who underwent HSCT using either myeloablative conditioning (MAC) or reduced-intensity conditioning (RIC) regimens. The patients belonged to a cohort treated at our hospitals between 2000 and 2018. HSCT was performed in 27 of 165 patients (16.4%). The median age at the time of HSCT was 3.6 years. Stem cell sources included bone marrow for 25 patients (HLA-matched sibling donors, n = 5; HLA-mismatched related donors, n = 2; HLA-matched/mismatched unrelated donors, n = 18) or cord blood for 2 patients. MAC or RIC regimens were used in 12 and 15 patients, respectively. Engraftment was successful in all 27 patients who underwent HSCT. Three patients who underwent HSCT using MAC regimens developed sinusoidal obstruction syndrome. The 3-year overall survival (OS) and failure-free survival rates (FFS) post-transplantations were 95.2% and 88.4%, respectively, with no significant differences between MAC and RIC regimens. Our data suggest that HSCTs using RIC regimens are effective and obtain engraftment with excellent OS and FFS for young DBA patients.

Complications of Stem Cell Transplantation that Affect Infections in Stem Cell Transplant Recipients, with Analogies to Patients with Hematologic Malignancies

This article discusses the complications of hematopoietic stem cell transplantion (HSCT) that affect infections in HSCT recipients, with analogies to patients with hematologic malignancies. Mucositis, with mucosal barrier disruption, is common and increases the risk of gram-positive and anaerobic bacterial, and fungal infections, and can evolve to typhlitis. Engraftment syndrome; graft-versus-host disease, hepatic sinusoidal obstruction syndrome; and posterior reversible encephalopathy syndrome can affect the infectious potential either directly from organ dysfunction or indirectly from specific treatment. Pulmonary infections can predispose to life threatening complications including diffuse alveolar hemorrhage, idiopathic pulmonary syndrome, bronchiolitis obliterans syndrome, and bronchiolitis obliterans with organizing pneumonia.

Identification and Management: Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease Eelated to Hematopoietic Stem Cell Transplantation

BACKGROUND

Sinusoidal obstruction syndrome (SOS), also called hepatic veno-occlusive disease (VOD), is a potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT) that affects about 1 in 7 patients undergoing this procedure. SOS/VOD is caused by the conditioning regimens administered prior to HSCT; in some cases, SOS/VOD results from chemotherapy alone. SOS/VOD usually develops within three weeks following HSCT; however, it can have later onset. 
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OBJECTIVES

Clearly understanding how SOS/VOD develops may support prompt detection and treatment when the condition arises.
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METHODS

Research on identification and management of SOS/VOD is summarized, and data from clinical trials are reviewed.
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FINDINGS

This article describes the syndrome, risk factors, signs and symptoms, and appropriate supportive care and treatment. The authors also offer some practical tips for detecting SOS/VOD and providing patient care, as well as the latest information on treating and preventing this condition.

Pharmacometabolomics for predicting variable busulfan exposure in paediatric haematopoietic stem cell transplantation patients

Owing to its narrow therapeutic range and high pharmacokinetic variability, optimal dosing for busulfan is important to minimise overexposure-related systemic toxicity and underexposure-related graft failure. Using global metabolomics, we investigated biomarkers for predicting busulfan exposure. We analysed urine samples obtained before busulfan administration from 59 paediatric patients divided into 3 groups classified by area under the busulfan concentration-time curve (AUC), i.e., low-, medium-, and high-AUC groups. In the high-AUC group, deferoxamine metabolites were detected. Phenylacetylglutamine and two acylcarnitines were significantly lower in the high-AUC group than in the low-AUC group. Deferoxamine, an iron-chelating agent that lowers serum ferritin levels, was detected in the high-AUC group, indicating that those patients had high ferritin levels. Therefore, in a retrospective study of 130 paediatric patients, we confirmed our hypothesis that busulfan clearance (dose/AUC) and serum ferritin level has a negative correlation (r = −0.205, P = 0.019). Ferritin, acylcarnitine, and phenylacetylglutamine are associated with liver damage, including free radical formation, deregulation of hepatic mitochondrial β-oxidation, and hyperammonaemia. Our findings reveal potential biomarkers predictive of busulfan exposure and suggest that liver function may affect busulfan exposure.

Current Review of Iron Overload and Related Complications in Hematopoietic Stem Cell Transplantation

Iron overload is an adverse prognostic factor for patients undergoing hematopoietic stem cell transplantation (HSCT). In the HSCT setting, pretransplant and early posttransplant ferritin and transferrin saturation were found to be highly elevated due to high transfusion requirements. In addition to that, post-HSCT iron overload was shown to be related to infections, hepatic sinusoidal obstruction syndrome, mucositis, liver dysfunction, and acute graft-versus-host disease. Hyperferritinemia causes decreased survival rates in both pre- and posttransplant settings. Serum ferritin levels, magnetic resonance imaging, and liver biopsy are diagnostic tools for iron overload. Organ dysfunction due to iron overload may cause high mortality rates and therefore sufficient iron chelation therapy is recommended in this setting. In this review the management of iron overload in adult HSCT is discussed.

The Prognostic Significance of Elevated Serum Ferritin Levels Prior to Transplantation in Patients With Lymphoma Who Underwent Autologous Hematopoietic Stem Cell Transplantation (autoHSCT): Role of Iron Overload

INTRODUCTION

Hematopoietic stem cell transplantation is a common and preferred treatment of lymphomas in many centers. Our goal was to determine the association between pretransplant iron overload and survival in patients who underwent autologous hematopoietic stem cell transplantation (autoHSCT).

PATIENTS AND METHODS

A total of 165 patients with lymphoma, who underwent autoHSCT between the years of 2007 and 2014, were included in this study. Ferritin levels were used to determine iron status; the cut-off value was 500 ng/mL. The relationship between iron overload and survival was assessed by statistical analysis.

RESULTS

The median ferritin level in the normal ferritin (ferritin < 500) group was 118 ng/mL (range, 9-494 ng/mL) and in the high-ferritin group (ferritin ≥ 500), it was 908 ng/mL (range, 503-4549 ng/mL). A total of 64 (38.8%) patients died during follow-up. Of these patients that died, 52 (81.25%) were in the high-ferritin group, and 12 (18.75%) were in the normal ferritin group (P ≤ .001). Twelve (14.1%) of 85 patients died in the normal ferritin group, and 52 (65.0%) of 80 patients died in the high-ferritin group. The overall mortality was significantly higher in the high-ferritin group (P < .001). The median overall survival was 42 months (range, 25-56 months) in the normal-ferritin group and20 months (range, 5-46) in the high-ferritin group. The difference between the groups was statistically significant (P < .001). The median disease-free survival was 39 months (range, 16-56) in the normal ferritin group and 10 months (range, 3-29) in the high-ferritin group. The difference between the groups was statistically significant (P < .001).

CONCLUSION

Elevated serum ferritin levels might predict poorer survival in autoHSCT recipients.

Revised diagnosis and severity criteria for sinusoidal obstruction syndrome/veno-occlusive disease in adult patients: a new classification from the European Society for Blood and Marrow Transplantation

Sinusoidal obstruction syndrome, also known as veno-occlusive disease (SOS/VOD), is a potentially life threatening complication that can develop after hematopoietic cell transplantation. Although SOS/VOD progressively resolves within a few weeks in most patients, the most severe forms result in multi-organ dysfunction and are associated with a high mortality rate (>80%). Therefore, careful attention must be paid to allow an early detection of SOS/VOD, particularly as drugs have now proven to be effective and licensed for its treatment. Unfortunately, current criteria lack sensitivity and specificity, making early identification and severity assessment of SOS/VOD difficult. The aim of this work is to propose a new definition for diagnosis, and a severity-grading system for SOS/VOD in adult patients, on behalf of the European Society for Blood and Marrow Transplantation.

Ferritin as an early marker of graft rejection after allogeneic hematopoietic stem cell transplantation in pediatric patients

Diagnosis of adverse events following hematopoietic stem cell transplantation (HSCT) is mainly assigned to clinical symptoms or biopsies and thus rather unspecific and/or invasive. Studies indicate a distinct role of serum ferritin in HSCT and its correlation with adverse events such as graft-versus-host disease (GvHD), veno-occlusive disease (VOD), or infections. However, published data on the relevance of ferritin as a prognostic marker for post-transplant adverse events is rare, especially in pediatric patients. The present study analyzes ferritin plasma concentrations of 138 pediatric patients after HSCT between 2007 and 2010 including the control group (n = 21). Given the initial results regarding ferritin as a significant predictor for acute graft rejection after allogeneic HSCT in 9 of the 138 pediatric patients, serum ferritin of all pediatric patients (n = 27) who experienced graft rejection between 2007 and 2014 was analyzed. In addition, laboratory parameters including C-reactive protein (CRP), lactate dehydrogenase (LDH), fibrinogen, and D-dimer as possible differentiation markers for graft rejection were determined. In 24 (88.9 %) of the 27 pediatric patients with graft rejection, a significant increase of ferritin levels was observed 1 to 7 days prior to (P < 0.0001) and at the time of graft rejection (P < 0.0001). Moreover, there was an increase of D-dimer, CRP, LDH, and fibrinogen 1-7 days before graft rejection. Ferritin increased significantly at time of VOD (P = 0.0067), at time of intestinal (P < 0.0001) and skin GvHD (P < 0.0001), and at time of sepsis (P = 0.0005) and bacteremia (P = 0.0029). Ferritin might serve as a readily available identification marker for differentiation and identification of adverse events after HSCT in combination with other laboratory markers.

Hepatic Veno-Occlusive Disease after Hematopoietic Stem Cell Transplantation: Risk Factors and Stratification, Prophylaxis, and Treatment

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), can develop in a subset of patients, primarily after myeloablative hematopoietic stem cell transplantation, but it also may occur after reduced-intensity conditioning. Severe VOD/SOS, typically characterized by multiorgan failure, has been associated with a mortality rate greater than 80%. Therefore, an accurate and prompt diagnosis of VOD/SOS is essential for early initiation of appropriate therapy to improve clinical outcomes. Moreover, some studies have support the use of prophylaxis for patients who are at high risk of developing VOD/SOS. This review summarizes risk factors associated with development of VOD/SOS, including pretransplantation patient characteristics and factors related to stem cell transplantation, that can facilitate patient stratification according to risk. The incidence of VOD/SOS, clinical features, and diagnostic criteria are reviewed. Data on emerging treatment strategies for patients with VOD/SOS are discussed in the context of recent treatment guidelines. Additionally, options for prophylaxis in individuals who are at increased risk are presented. Although historically only those patients with moderate to severe VOD/SOS have been treated, early therapy and prophylaxis may be appropriate for many patients and may have the potential to improve patients' outcomes and survival, including for those with nonsevere disease.

Successful use of reduced-intensity conditioning and matched-unrelated hematopoietic stem cell transplant in a child with Diamond-Blackfan anemia and cirrhosis

For patients with DBA who are transfusion dependent, HSCT is the only cure. Chronic transfusions can lead to cirrhosis secondary to iron overload, making them poor candidates for myeloablative HSCT. RIC regimens are associated with lower morbidity and mortality compared to myeloablative regimens, but use of RIC in DBA has been limited. Here we present a 14-yr-old girl with DBA and multiple comorbidities including liver cirrhosis, who underwent MUD HSCT utilizing a RIC regimen that is novel to this condition. She tolerated the regimen well, and at 21 months, she remains transfusion independent with chimerisms at 99%.

Association of iron overload with allogeneic hematopoietic cell transplantation outcomes: a prospective cohort study using R2-MRI-measured liver iron content

Using liver magnetic resonance imaging (R2-MRI) to quantify liver iron content (LIC), we conducted a prospective cohort study to determine the association between iron overload and adult allogeneic hematopoietic cell transplantation (HCT) outcomes. Patients received pretransplant ferritin measurements; patients with ferritin >500 ng/mL underwent R2-MRI. Patients were defined as no iron overload (N = 28) and iron overload (LIC >1.8 mg/g; N = 60). Median LIC in the iron-overload group was 4.3 mg/g (range, 1.9-25.4). There was no difference in the 1-year probability of overall survival, nonrelapse mortality, relapse, acute or chronic graft-versus-host disease, organ failure, infections, or hepatic veno-occlusive disease between groups. We also found no difference in the cumulative incidence of a composite end point of nonrelapse mortality, any infection, organ failure, or hepatic veno-occlusive disease (1-year cumulative incidence, 71% vs 80%; P = .44). In multivariate analyses, iron-overload status did not impact risks of overall mortality (relative risk = 2.3; 95% confidence interval, 0.9-5.9; P = .08). In conclusion, we found no association between pretransplant iron overload and allogeneic HCT outcomes. Future studies in this population should use LIC to define iron overload instead of ferritin.

Pharmacogenetic study of deferasirox, an iron chelating agent

Transfusion-associated iron overload induces systemic toxicity. Deferasirox, a convenient long acting oral agent, has recently been introduced in clinical practice with a promising efficacy. But there are some patients who experience drug-related toxicities and cannot tolerate it. To investigate effect of genetic variations on the toxicities and find optimal target population, we analyzed the genetic polymorphisms of UDP-glucuronosyltransferase 1A (UGT1A) subfamily, multi-drug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP). A total of 20 functional genetic polymorphisms were analyzed in 98 patients who received deferasirox to reduce transfusion-induced iron overload. We retrospectively reviewed the medical records to find out the drug-related toxicities. Fifteen (15.3%) patients developed hepatotoxicity. Patients without wild-type allele carrying two MRP2 haplotypes containing −1774 del and/or −24T were at increased risk of developing hepatotoxicity compared to patients with the wild-type allele on multivariate analysis (OR = 7.17, 95% CI = 1.79–28.67, P = 0.005). Creatinine elevation was observed in 9 patients (9.2%). Body weight ≥40 kg and homozygosity for UGT1A1*6 were risk factors of creatinine elevation (OR = 8.48, 95% CI = 1.7–43.57, P = 0.010 and OR = 14.17, 95% CI = 1.34–150.35, P = 0.028). Our results indicate that functional genetic variants of enzymes to metabolize and transport deferasirox are associated with drug-related toxicities. Further studies are warranted to confirm the results as the pharmacogenetic biomarkers of deferasirox.

Veno-occlusive disease in hematopoietic stem cell transplantation recipients

Veno-occlusive disease (VOD) is a potentially fatal complication of hematopoietic stem cell transplantation that affects the liver, as well as other organs. Although mild cases resolve on their own, severe cases of VOD carry a high mortality rate. The diagnosis usually is clinically based, with nonspecific signs such as weight gain, ascites, hepatomegaly, right upper quadrant abdominal pain, and elevated serum bilirubin. Although studies are ongoing, no U.S. Food and Drug Administration-approved treatments for VOD exist to date. Therefore, supportive care is a critical part of the treatment plan. Oncology nurses should be familiar with the risk factors and clinical signs of VOD so that patients can be monitored closely for its occurrence. Accurate and timely recognition of VOD is crucial for appropriate treatment.

The management of iron overload in allogeneic hematopoietic stem cell transplant (alloHSCT) recipients: where do we stand?

Iron overload (IO), primarily related to multiple red blood cell transfusions, is a relatively common complication in hematopoietic stem cell transplant (HSCT) recipients. Elevated pretransplant ferritin levels have been reported to increase the risk of non-relapse mortality following HSCT and might influence the risk of acute and chronic graft versus host disease. IO has been shown to be an important cause of mortality and morbidity in patients who have undergone alloHSCT (Armand et al., Blood 109:4586-4588, 2007; Kim et al., Acta Haematol 120:182-189, 2008; Kataoka et al., Biol Blood Marrow Transplant 15:195-204, 2009). We know that excessive iron accumulation results in tissue damage and organ failure, mainly as a result of the generation of free radicals that cause oxidative damage and organ dysfunction (e.g., hepatotoxicity, cardiotoxicity, and endocrine dysfunction) (Altes et al., Bone Marrow Transplantation 29: 987-989, 2002; Papanikolaou et al., Toxicol Appl Pharmac 202:199-211, 2005). In the last decade, efforts have been directed toward identifying alternative treatment for IO in alloHSCT recipients to maintain improved transplant outcomes.

Does iron overload really matter in stem cell transplantation?

A growing body of evidence suggests that iron overload is associated with inferior outcomes after myeloablative allogeneic hematopoietic stem cell transplantation (HSCT). However, all of those studies used surrogate markers of iron overload, especially serum ferritin, and most had a retrospective design. We conducted a prospective observational study in patients with myelodysplastic syndrome or acute leukemia undergoing myeloablative HSCT. Forty-five patients who were followed for over 1 year, with serial measurements of serum iron parameters, as well as liver and cardiac magnetic resonance imaging. There was no significant increase in ferritin, liver or cardiac iron content in the 12 months following HSCT. Although serum ferritin still appeared to have prognostic significance, as previously reported, pre-HSCT iron overload (as reflected in liver iron content) was not associated with increased mortality, relapse, or graft-versus-host disease. These results raise the possibility that the adverse prognostic impact of pre-HSCT hyperferritinemia may be related to factors independent of iron overload.

Efficacy and safety of oral deferasirox treatment in the posttransplant period for patients who have undergone allogeneic hematopoietic stem cell transplantation (alloHSCT)

Iron overload is considered to be associated with various complications in patients who undergo both allogeneic (allo) and autologous hematopoietic stem cell transplantation (HSCT). A total of 23 alloHSCT recipients who started deferasirox treatment due to hyperferritinemia (ferritin ≥1,000 ng/mL) were analyzed retrospectively. The demographic characteristics, data about deferasirox treatment, and history of phlebotomy were obtained from the patients' files. The reduction in posttreatment ferritin levels was found statistically significant compared with pretreatment ferritin levels in both def+phlebotomy and def+nonphlebotomy groups (p = 0.025 and 0.017, respectively). The liver enzymes, especially ALT and bilirubins, were significantly reduced after the treatment (p < 0.05). The deferasirox treatment reduced pretreatment ferritin levels below the level of 1,000 ng/mL in a median period of 94 days, and these data were found to be statistically significant (p < 0.05). The median treatment duration time with deferasirox was 94 days (72-122). The most common adverse effects were nausea and vomiting, which occurred in three of the patients (13%). In conclusion, our data suggest that oral deferasirox treatment may be used as a safe and effective alternative method for reducing iron overload in alloHSCT recipients, whether combined with or without phlebotomy.

Iron overload and allogeneic hematopoietic stem-cell transplantation

Iron overload is frequently observed in patients with hematologic diseases before and after allogeneic stem-cell transplantation because they usually receive multiple red blood cell transfusions. Elevated pretransplant serum ferritin levels, which are widely used as indicators of body iron status, are significantly associated with a lower overall survival rate and a higher incidence of treatment-related complications; for example, infections and hepatic veno-occlusive disease. As serum ferritin levels are affected, not only by iron loading but also by inflammation, imaging techniques to quantify tissue iron levels have been developed, for example, quantitative MRI using the transverse magnetic relaxation rate, and superconducting quantum interference devices. Iron chelators, such as deferasirox, a new oral iron-chelating agent, reduce iron load in transfusion-dependent patients. Iron-chelating therapy before and/or after transplantation is a promising strategy to improve the clinical outcomes of transplant patients with iron overload. However, further research is needed to prove the direct relationship between iron overload and adverse outcomes, as well as to determine the effects of treatment for iron overload on outcomes of allogeneic stem-cell transplantation.

Solid organ transplants following hematopoietic stem cell transplant in children

SOT may be indicated for a select group of pediatric patients who experience permanent organ failure following HSCT. However, there is limited information available about outcomes. We identified eight children at our center who received an SOT following an HSCT. Patients were six months to 18 yr at HSCT. Diseases for which children underwent HSCT included thalassemia, Wiskott-Aldrich syndrome, Shwachman-Diamond/bone marrow failure, sickle cell disease (SCD), erythropoietic porphyria (EP), ALL, chronic granulomatous disease, and neuroblastoma. Time from HSCT to SOT was 13 days to seven yr (median, 27 months. Lung SOT was performed for two patients with BO, kidney transplants for three patients, and liver transplants for three patients (VOD, chronic GVHD). Seven patients are alive with functioning allografts 6-180 months from SOT. Advances in organ procurement, operative technique, immunosuppressant therapy, and infection control may allow SOT for a select group of patients post-HSCT. However, scarcity of donor organs available in a timely fashion continues to be a limiting factor. Children who have undergone HSCT and develop single organ failure should be considered for an SOT if there is a high likelihood of cure of the primary disease.

Iron overload: predictor of adverse outcome in hematopoietic stem cell transplantation

INTRODUCTION

Iron overload is an important problem in candidates for and survivors of hematopoietic stem cell transplantation (HSCT), and affects long-term outcome and survival. The objective of the present study was to determine the effect of iron overload on early toxic or infectious complications and survival.

PATIENTS AND METHODS

We retrospectively reviewed the medical records for 250 adult patients (162 men and 88 women; median [range] age, 34 [16-71] years who underwent HSCT between September 2003 and August 2008. The HSCT grafts were autologous in 102 patients, and allogeneic in 148.

RESULTS

Follow-up was 315 (1-1809) days. Mean (SD) pre-HSCT serum ferritin concentration was 1402.6 (5016.2) ng/mL in the entire group, 647.6 (1204.3 ng/mL in autologous recipients, and 1410.6 (2410.4) ng/mL in allogeneic recipients. Twenty-eight autologous graft recipients (27.4%) and 102 allogeneic recipients (68.9%) demonstrated serum ferritin concentrations of 500 ng/mL or greater, and were classified as the high-ferritin group. High ferritin concentrations were significantly associated with toxic or infectious complications including mucositis, fungal infections, pneumonia, and sinusoidal obstruction syndrome in the early post-HSCT setting. A significant effect of pre-HSCT ferritin concentration on overall survival and transplant-related mortality was observed. The effect of pre-HSCT ferritin on survival was independent of the comorbidity index at Cox regression analysis. In the entire study population, the probability of survival was significantly lower when ferritin concentration was greater than 500 ng/mL.

CONCLUSION

Transplant-related mortality has decreased substantially with the development of supportive treatments. Pretransplantation risk assessment and risk-adapted strategies such as decreasing iron overload might further improve transplant-related complications.

Iron overload in patients with acute leukemia or MDS undergoing myeloablative stem cell transplantation

Patients with hematologic malignancies undergoing allogeneic stem cell transplantation (HSCT) commonly have an elevated serum ferritin prior to HSCT, which has been associated with increased mortality after transplantation. This has led to the suggestion that iron overload is common and deleterious in this patient population. However, the relationship between serum ferritin and parenchymal iron overload in such patients is unknown. We report a prospective study of 48 patients with acute leukemia (AL) or myelodysplastic syndromes (MDS) undergoing myeloablative HSCT, using magnetic resonance imaging (MRI) to estimate liver iron content (LIC) and cardiac iron. The median (and range) pre-HSCT value of serum ferritin was 1549 ng/mL (20-6989); serum hepcidin, 59 ng/mL (10-468); labile plasma iron, 0 LPI units (0.0-0.9). Eighty-five percent of patients had hepatic iron overload (HIO), and 42% had significant HIO (LIC ≥5.0 mg/gdw). Only 1 patient had cardiac iron overload. There was a strong correlation between pre-HSCT serum ferritin and estimated LIC (r = .75), which was mostly dependent on prior transfusion history. Serum hepcidin was appropriately elevated in patients with HIO. Labile plasma iron elevation was rare. A regression calibration analysis supported the hypothesis that elevated pre-HSCT LIC is significantly associated with inferior post-HSCT survival. These results contribute to our understanding of the prevalence, mechanism, and consequences of iron overload in HSCT.

Deferasirox use after hematopoietic stem cell transplantation in pediatric patients with beta-thalassemia major: preliminary results

There are limited data on the posttransplantation pharmacological treatment of iron overload in ex-thalassemic patients and the current approach is phlebotomy. The authors chelated 2 ex-thalassemic patients after hematopoietic stem cell transplantation with deferasirox for 6 and 24 months. Although serum ferritin levels decreased, cardiac and hepatic iron load, measured by T2* magnetic resonance imaging (MRI), showed decrease in iron overload in these organs. The drug was tolerated well by both patients and no adverse effect on donor hematopoiesis was observed. This preliminary study demonstrates that deferasirox is well tolerated in these patients and will be a good potential therapy when more data have been obtained from larger studies.

A prospective study of iron overload management in allogeneic hematopoietic cell transplantation survivors

We report the results of a single-center, prospective evaluation for iron overload and subsequent treatment in 147 adult allogeneic hematopoietic cell transplantation (HCT) recipients who survived beyond 1 year after transplantation. Patients were screened by serum ferritin level; those with ferritin >1000 ng/mL underwent liver R2 magnetic resonance imaging to estimate liver iron concentration (LIC; normal < or =1.8 mg/g). Patients with significant iron overload (defined as LIC > or =5 mg/g), based on physician and patient preference, were offered observation only, phlebotomy, or enrollment in a pilot study of deferasirox. Sixteen patients had significant iron overload. Their median age was 51 years (range, 29-64 years), and they had survived a median of 21 months (range, 12-114 months). All 16 patients were transfusion-independent at study enrollment. Five patients received no treatment (median LIC, 6.4 mg/g; range, 5.1-28.3 mg/g), 8 underwent phlebotomy (median LIC, 13.1 mg/g; range, 7.8-43.0 mg/g), and 3 received daily deferasirox 20 mg/kg/day orally for 6 months (LIC, 6.3, 9.0, and 19.9 mg/g). Two patients had abnormal liver function tests, and 1 patient each had cirrhosis and unexplained congestive heart failure; all 4 of these patients underwent phlebotomy. Follow-up serum ferritin concentrations decreased spontaneously in 4 patients in the observation-only arm. Phlebotomy was generally well tolerated. Deferasirox also was well tolerated and led to decreased LIC after 6 months of therapy in all 3 patients. Phlebotomy is feasible in the majority of allogeneic HCT recipients who have survived for > or =1 year after HCT and have significant iron overload. Although the number of subjects is small, deferasirox may be a safe and effective alternative for allogeneic HCT survivors with iron overload who cannot undergo phlebotomy.

Hepatic veno-occlusive disease in children after hematopoietic stem cell transplantation: incidence, risk factors, and outcome

Four hundred and sixty-seven hematopoietic stem cell transplantations (HSCTs) (217 autologous and 250 allogeneic HSCT) were performed in 374 children at four pediatric HSCT centers in Korea from January 2005 to December 2007. Among 467 transplants, veno-occlusive disease (VOD) developed in 72 transplants (15.4%) at a median of 10 days after HSCT. Multivariate analysis showed that BU or TBI-containing regimen (P=0.002), VOD prophylaxis without lipo-prostaglandin E1 (PGE1) (P=0.012), number of previous HSCT (P=0.014), and pretransplant serum ferritin (P=0.018) were independent risk factors for developing VOD. Mean serum ferritin levels were significantly higher in HSCT with VOD (2109.6+/-2842.5 ng/ml) than in HSCT without VOD (1315.9+/-1094.4 ng/ml) (P<0.001). The relative risk of death within 100 days of HSCT in transplants with VOD compared with transplants without VOD was 3.39 (confidence interval: 1.78-6.45). Our results suggest that lipo-PGE1 might have a protective effect against the development of VOD, and pretransplant serum ferritin could act as a risk factor for VOD. A larger prospective study is needed to confirm a possible role of lipo-PGE1 and iron chelation therapy in reducing the incidence of VOD.

Impact of pre-transplant serum ferritin on outcomes of patients with myelodysplastic syndromes or secondary acute myeloid leukaemia receiving reduced intensity conditioning allogeneic haematopoietic stem cell transplantation

We report on a retrospective analysis examining the influence of pre-transplant serum ferritin on transplant outcomes of 99 MDS patients receiving reduced intensity conditioning (RIC) HSCT. The median pre-transplant ferritin value was 1992 ng/ml (range: 6-9580 ng/ml). No patients received iron chelation therapy preceding transplantation. On univariate analysis, there was a strong correlation between a higher pre-transplant serum ferritin (>1500 ng/ml) and a significantly inferior 3-year OS (64.6+/-7.5% vs 39.6+/-7.3%, p=0.01). However, pre-transplant serum ferritin did not influence 3-year TRM (20.2+/-7% vs 27.4+/-7%, p=0.24). There was no difference in infection-related mortality, and incidence of acute or chronic GvHD between cohorts. On multivariate analysis, a raised serum ferritin (HR: 2.00, 95% CI: 0.97-3.57, p=0.03), and the presence of >5% bone marrow blasts at time of transplantation (HR: 2.14, 95% CI: 0.84-4.58, p=0.06) were independent predictors of an inferior overall survival. However, pre-transplant serum ferritin was not a significant predictor of disease-free survival, relapse or TRM. When compared with myeloablative regimens, RIC regimens may attenuate the impact of iron overload related end-organ toxicity. Prospective studies incorporating alternative biomarkers of iron metabolism alongside serum ferritin levels are needed to improve our understanding of the significance of iron overload in MDS patients undergoing allogeneic transplantation.

Clinical significance of serum hepcidin levels on early infectious complications in allogeneic hematopoietic stem cell transplantation

The association of iron overload with complications of allogeneic hematopoietic stem cell transplantation (HSCT) has been suggested in previous studies. Because hepcidin plays a central role in the regulation of iron homeostasis, we analyzed the association between pretransplant serum hepcidin-25 levels and early infectious complications after allogeneic HSCT. We studied 55 consecutive adult patients with a median age of 47 years (range: 20-64 years) who underwent allogeneic HSCT for hematologic malignancies at our institution. Thirty-two patients had myelogenous malignancies; the remaining 23 had lymphogenous malignancies. The median pretransplant serum hepcidin level of patients in the study was 21.6 ng/mL (range: 1.4-371 ng/mL), which was comparable to that of healthy volunteers (median: 19.1 ng/mL [range: 2.3-37 ng/mL]; n = 17). When cumulative incidences of documented bacterial and cytomegalovirus (CMV) infections at day 100 were compared according to pretransplant hepcidin-25 levels, the incidence of bacterial, but not CMV, infection, was significantly higher in the high-hepcidin group (> or = 50 ng/mL; n = 17) than in the low-hepcidin group (<50 ng/mL; n = 38) (65% [95% confidence interval, 38%-82%] versus 11% [3%-23%]; P < .001). This finding was confirmed by multivariate Cox analysis adjusted for confounders, including pretransplant ferritin and C-reactive protein (CRP) levels. No fungal infection was documented in either group. These results suggest that the pretransplant serum hepcidin-25 level may be a useful marker for predicting the risk of early bacterial complications after allogeneic HSCT. Larger prospective studies are, however, warranted to confirm our findings.

Absence of VOD in paediatric thalassaemic HSCT recipients using defibrotide prophylaxis and intravenous Busulphan

Hepatic veno-occlusive disease (VOD) is a common complication of haematopoietic stem cell transplantation (HSCT), with reported incidences of 5-40% in children. Recently, defibrotide (DF) has been successfully used as prophylaxis and treatment of VOD. This study reports data on 63 human leucocyte antigen-matched HSCT performed in 57 children affected by beta thalassemia at very high risk for developing VOD (liver fibrosis, iron overload, hepatitis C virus infections, busulphan-based conditioning, methotraexate + ciclosporine). All patients received a busulphan-based conditioning regimen, either orally (four HSCT) or intravenously (59 HSCT). All patients received oral DF (40 mg/kg per day, final dose) as VOD prophylaxis from median day -9 to median day +29. In order to overcome the lack of oral paediatric formulations, a galenic formulation was administered. DF was well tolerated. Only one patient fulfilled Seattle Criteria for VOD diagnosis. This patient had discontinued DF 6 d prior to VOD onset, due to high risk of haemorrhage. We concluded that oral defibrotide prophylaxis and i.v. busulphan safely abated VOD incidence in high-risk patients who had undergone HSCT. A galenic preparation of oral DF also permits this treatment in low-weight patients. Costs of DF prophylaxis are acceptable considering the reduced incidence of VOD.

Serum ferritin as risk factor for sinusoidal obstruction syndrome of the liver in patients undergoing hematopoietic stem cell transplantation

Hepatic sinusoidal obstruction syndrome (SOS) is a serious complication in hematopoietic stem cell transplant (HSCT) recipients. To determine the impact of pretransplantation hyperferritinemia on the risk of SOS after HSC transplantation, we retrospectively studied 427 HSCT recipients (179 autologous and 248 allogeneic). Serum ferritin levels were measured before transplantation. Patients with and without a diagnosis of SOS were compared regarding demographics; underlying disease; transplant characteristics; receipt of imatinib, busulfan, total body irradiation, gemtuzumab, vancomycin, acyclovir, or methotrexate; and baseline serum ferritin. Univariate and multivariate (stepwise logistic regression) analyses were performed. SOS was diagnosed in 88 patients (21%) at a median of 10 days (range, 2-29 days) after transplantation. By multivariate analysis, allogeneic HSC transplantation (odds ratio [OR] = 8.25; 95% confidence interval [95% CI], 3.31-20.57), receipt of imatinib (OR = 2.60; 95% CI, 1.16-5.84), receipt of busulfan (OR = 2.18; 95% CI, 1.25-3.80), and ferritin serum level higher than 1000 ng/dL (OR = 1.78; 95% CI, 1.02-3.08) were risk factors for SOS. A ferritin serum level higher than 1000 ng/dL in the pretransplantation period is an independent risk factor for SOS. The results suggest the need for prospective studies addressing the use of iron chelation in the pretransplantation period.

Effect of iron overload and iron-chelating therapy on allogeneic hematopoietic SCT in children

Iron overload is known to increase complications of hematopoietic SCT (HSCT). We investigated the association of pre-transplant ferritin level with complications and survival after allogeneic HSCT, and evaluated the efficacy of iron-chelating therapy before HSCT. We retrospectively reviewed 101 patients who underwent allogeneic HSCT and divided these patients into three groups: F>1000, patients with ferritin level above 1000 ng/ml at the time of HSCT; F<1000, patients whose ferritin levels were maintained below 1000 ng/ml before HSCT without iron-chelating therapy; IC, patients with ferritin level decreased to less than 1000 ng/ml after iron-chelating therapy before HSCT. In the comparison between the F>1000 group and the F<1000 group, hyperbilirubinemia and treatment-related mortality (TRM) were significantly higher in the F>1000 group. The F>1000 group also showed decreased OS and EFS. In the comparison of the F<1000 and IC groups, there was no significant difference in complications and survival. When compared with the F>1000 group, the IC group showed lower TRM and higher survival. Elevated serum ferritin level was associated with increased TRM and decreased survival, and the analysis of the IC group suggested the benefit of iron-chelating therapy to improve the outcome of HSCT.

Iron overload adversely affects outcome of allogeneic hematopoietic cell transplantation

Iron overload is common in patients undergoing allogeneic hematopoietic cell transplantation (HCT) for hematologic disorders. Serum ferritin, a marker of tissue iron overload, was measured immediately before transplant in adult patients undergoing myeloablative HCT from matched sibling or unrelated donors. The effect of elevated pretransplant ferritin (defined as ferritin >or=1000 ng/ml) on day 100 mortality, overall survival, acute GVHD and infectious complications was assessed. Data on 190 patients were analyzed. In univariate analysis, the high-ferritin group had increased day 100 mortality (20 vs 9%, P=0.038), decreased overall survival (log-rank test: P-value=0.004), increased acute GVHD/death (63 vs 43%, P=0.009) and increased incidence of blood stream infections (BSIs)/death (60 vs 44%, P=0.042). In a multivariate analysis, high ferritin was associated with increased risk of death (Cox model: hazard ratio=2.28, P=0.004), increased day 100 mortality (generalized linear model (GLM) odds ratio=3.82, P=0.013), increased incidence of acute GVHD/death (GLM odds ratio=3.11, P=0.001) and increased risk of BSI/death (GLM odds ratio=1.99, P=0.032). The results remained similar when serum ferritin was considered a continuous variable. Elevated serum ferritin adversely impacts on overall survival and increases the likelihood of acute GVHD and BSI after allogeneic HCT.

Defibrotide for the treatment of hepatic veno-occlusive disease in children

BACKGROUND

This retrospective report describes experience with defibrotide in children with hepatic veno-occlusive disease (HVOD) following hematopoietic progenitor cell transplant (HPCT) in a single institution.

PROCEDURE

Children who had undergone HPCT between February 1999 and June 2001 and between July 2003 and September 2004 and who received defibrotide during their admission were identified. Demographic data and information regarding the clinical course of these patients were abstracted from their health records.

RESULTS

Fourteen children (mean age: 9.3 years; range: 0.4-18.1) who underwent HPCT during the study period received defibrotide for the treatment of HVOD; nine were girls. Most patients underwent HPCT for hematologic malignancies (8/14) and received matched unrelated donor transplants (8/14). Conditioning regimens included cyclophosphamide with total body irradiation (5/14) and busulfan followed by cyclophosphamide (7/14). HVOD was diagnosed on transplant day -4 to +33 (median: +10.5); defibrotide was started on transplant day -4 to +40 (median: +12). The median initial defibrotide dose was 33 mg/kg/day (11-40 mg/kg/day); the median maximum defibrotide dose was 38.5 mg/kg/day (11-81 mg/kg/day). The median duration of defibrotide therapy was 16 days (4-37 days). Defibrotide was discontinued due to clinical improvement (9), death (3), drug unavailability (1), and neurological toxicity (1). Gastrointestinal hemorrhage was observed in two patients and intra-cranial hemorrhage was observed in one patient during defibrotide therapy. The survival rate to day +100 was 79%.

CONCLUSIONS

Defibrotide appears to be an effective and relatively safe treatment for children with HVOD.

Elevated plasma ferritin and busulfan pharmacodynamics during high-dose chemotherapy regimens in children with malignant solid tumors

Hepatic veno-occlusive disease (HVOD) is a frequent complication during hematopoietic stem-cell transplantation (HSCT). A strong relationship has been demonstrated between busulfan exposure and HVOD for busulfan-cyclophosphamide and allogeneic HSCT in adults. Busulfan disposition after the first intake was studied in 77 children treated for solid malignancies with high-dose busulfan-containing regimens and autologous HSCT. Busulfan was combined with cyclophosphamide and melphalan (n=30), melphalan (n=27), and thiotepa (n=20). No relationship was observed between busulfan exposure and HVOD. In contrast, plasma ferritin at baseline was higher in patients with HVOD (750 ng/ml (20-3,110)) compared with those without HVOD (189 ng/ml (8-3,967), P=0.012). Multivariate analysis showed that a ferritin level exceeding 300 ng/ml was the only risk factor for HVOD with an odds ratio of 4.0 (confidence interval 95% (1.5-11.2), P=0.0071). A high ferritin level at baseline was explained by the diagnosis of neuroblastoma, related treatments and transfusions.

Prognostic impact of elevated pretransplantation serum ferritin in patients undergoing myeloablative stem cell transplantation

Iron overload could be a significant contributor to treatment-related mortality (TRM) for patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT). We studied 590 patients who underwent myeloablative allogeneic HSCT at our institution, and on whom a pretransplantation serum ferritin was available. An elevated pretransplantation serum ferritin level was strongly associated with lower overall and disease-free survival. Subgroup multivariable analyses demonstrated that this association was restricted to patients with acute leukemia or myelodysplastic syndrome (MDS); in the latter group, the inferior survival was attributable to a significant increase in TRM. There was also a trend toward an increased risk of veno-occlusive disease in patients with high ferritin. Our results argue that iron overload plays an important role in transplantation outcome for patients with acute leukemia or MDS, as it does in thalassemia. They also suggest future prospective trials to examine the potential benefit of chelation therapy in this setting.

The hemochromatosis C282Y allele: a risk factor for hepatic veno-occlusive disease after hematopoietic stem cell transplantation

Hepatic veno-occlusive disease (HVOD) is a serious complication of hematopoietic stem cell transplantation (HSCT). Since the liver is a major site of iron deposition in HFE-associated hemochromatosis, and iron has oxidative toxicity, we hypothesized that HFE genotype might influence the risk of HVOD after myeloablative HSCT. We determined HFE genotypes in 166 HSCT recipients who were evaluated prospectively for HVOD. We also tested whether a common variant of the rate-limiting urea cycle enzyme, carbamyl-phosphate synthetase (CPS), previously observed to protect against HVOD in this cohort, modified the effect of HFE genotype. Risk of HVOD was significantly higher in carriers of at least one C282Y allele (RR=3.7, 95% CI 1.2-12.1) and increased progressively with C282Y allelic dose (RR=1.7, 95% CI 0.4-6.8 in heterozygotes; RR=8.6, 95% CI 1.5-48.5 in homozygotes). The CPS A allele, which encodes a more efficient urea cycle enzyme, reduced the risk of HVOD associated with HFE C282Y. We conclude that HFE C282Y is a risk factor for HVOD and that CPS polymorphisms may counteract its adverse effects. Knowledge of these genotypes and monitoring of iron stores may facilitate risk-stratification and testing of strategies to prevent HVOD, such as iron chelation and pharmacologic support of the urea cycle.

Genomic screening and complications of hematopoietic stem cell transplantation: has the time come?

The occurrence of toxic complications following hematopoietic stem cell transplantation (HSCT) is highly variable and dependent on a multitude of host, donor, and treatment factors. The increasingly broad indications for HSCT and the need to provide this treatment option to older and/or more debilitated patients emphasizes the importance of refining our methods of predicting and ameliorating these toxicities. Late complications (occurring after day 100) also pose a threat to quality of life after HSCT. Genetic polymorphisms in key molecular pathways in the host are likely to contribute significantly to the observed variability in the development HSCT-associated complications. Hepatic veno-occlusive disease and acute lung injury, two of the most serious organ toxicities that occur, represent useful paradigms for the identification of genetic polymorphisms in enzyme systems that modulate local and systemic responses to oxidant stress during transplant conditioning therapy. Ongoing studies in this area are providing clues to the prevention of adverse clinical outcomes based on the genetic milieu. This review of studies in HSCT that explore genetic risk factors for transplant complications indicates that significant progress is being made in this rapidly evolving area. However, further large-scale clinical and translational studies are needed before genomic screening can be widely used to individualize treatment.

Rust and corrosion in hematopoietic stem cell transplantation: the problem of iron and oxidative stress

Iron overload is a common acute and long-term event associated with autologous and allogeneic hematopoietic stem cell transplantation (HSCT). In a state of iron excess, free iron becomes available to catalyze the conversion of reactive oxygen species (ROS) intermediates such as superoxide anion (O2*-) and hydrogen peroxide (H2O2) to highly toxic free radicals such as hydroxyl radical (OH*). ROS may help to promote chronic liver disease, sinusoidal obstruction syndrome, idiopathic pneumonia syndrome and bacterial, fungal and other opportunistic infections. Phlebotomy has been effectively and safely used to deplete excess iron stores post-HSCT in thalassemic and other iron-overloaded patients. Intracellular iron levels may also be decreased through pharmacologic chelating agents, while antioxidants such as N-acetylcysteine, glutamine (glutathione precursor) and captopril have been shown to replenish glutathione redox potential and scavenge free radicals. A better understanding of the mechanisms involved in the iron-generated pro-oxidant state associated with HSCT will likely lead to reduced toxicity and improved patient outcomes.