Malignancy in patients with sickle cell disease

Haematopoietic stem cell health in sickle cell disease and its implications for stem cell therapies and secondary haematological disorders

Gene modification of haematopoietic stem cells (HSCs) is a potentially curative approach to sickle cell disease (SCD) and offers hope for patients who are not eligible for allogeneic HSC transplantation. Current approaches require in vitro manipulation of healthy autologous HSC prior to their transplantation. However, the health and integrity of HSCs may be compromised by a variety of disease processes in SCD, and challenges have emerged in the clinical trials of gene therapy. There is also concern about increased susceptibility to haematological malignancies during long-term follow up of patients, and this raises questions about genomic stability in the stem cell compartment. In this review, we evaluate the evidence for HSC deficits in SCD and then discuss their potential causation. Finally, we suggest several questions which need to be addressed in order to progress with successful HSC manipulation for gene therapy in SCD.

Somatic EPAS1 Variants in Pheochromocytoma and Paraganglioma in Patients With Sickle Cell Disease

CONTEXT

Somatic EPAS1 variants account for 5% to 8% of all pheochromocytoma and paragangliomas (PPGL) but are detected in over 90% of PPGL in patients with congenital cyanotic heart disease, where hypoxemia may select for EPAS1 gain-of-function variants. Sickle cell disease (SCD) is an inherited hemoglobinopathy associated with chronic hypoxia and there are isolated reports of PPGL in patients with SCD, but a genetic link between the conditions has yet to be established.

OBJECTIVE

To determine the phenotype and EPAS1 variant status of patients with PPGL and SCD.

METHODS

Records of 128 patients with PPGL under follow-up at our center from January 2017 to December 2022 were screened for SCD diagnosis. For identified patients, clinical data and biological specimens were obtained, including tumor, adjacent non-tumor tissue and peripheral blood. Sanger sequencing of exons 9 and 12 of EPAS1, followed by amplicon next-generation sequencing of identified variants was performed on all samples.

RESULTS

Four patients with both PPGL and SCD were identified. Median age at PPGL diagnosis was 28 years. Three tumors were abdominal paragangliomas and 1 was a pheochromocytoma. No germline pathogenic variants in PPGL-susceptibility genes were identified in the cohort. Genetic testing of tumor tissue detected unique EPAS1 variants in all 4 patients. Variants were not detected in the germline, and 1 variant was detected in lymph node tissue of a patient with metastatic disease.

CONCLUSION

We propose that somatic EPAS1 variants may be acquired through exposure to chronic hypoxia in SCD and drive PPGL development. Future work is needed to further characterize this association.

Sickle Cell Disease: From Genetics to Curative Approaches

Sickle cell disease (SCD) is a monogenic blood disease caused by a point mutation in the gene coding for β-globin. The abnormal hemoglobin [sickle hemoglobin (HbS)] polymerizes under low-oxygen conditions and causes red blood cells to sickle. The clinical presentation varies from very severe (with acute pain, chronic pain, and early mortality) to normal (few complications and a normal life span). The variability of SCD might be due (in part) to various genetic modulators. First, we review the main genetic factors, polymorphisms, and modifier genes that influence the expression of globin or otherwise modulate the severity of SCD. Considering SCD as a complex, multifactorial disorder is important for the development of appropriate pharmacological and genetic treatments. Second, we review the characteristics, advantages, and disadvantages of the latest advances in gene therapy for SCD, from lentiviral-vector-based approaches to gene-editing strategies.

Impact of Imatinib on reducing the painful crisis in patients with sickle cell disease

INTRODUCTION

Sickle cell disease (SCD) is a common hemoglobinopathy worldwide that causes painful crises and hospitalization of patients. These attacks decrease survival and cause chronic end-organ damage in these patients.

HYPOTHESIS

For this reason, finding new treatment approaches could be helpful.

METHOD

In this study, Imatinib was applied as a mast cell inhibitor to reduce pain crises in these patients. Seven patients resistant to hydroxyurea and folic acid treatment and who had at least four painful crises per year with hospitalization were enrolled in this study with treatment with Imatinib (100 mg, twice daily). Subsequently, the number and duration of hospitalizations, analgesic requirement, the severity of chronic pain, and changes in the hematological parameters of these patients were evaluated before and after the treatment.

RESULTS

The data showed that the total number of hospitalizations and the entire duration of hospitalizations were reduced 16 times after treatment with Imatinib, without apparent changes in hematological parameters. Also, the demand for pethidine, tramadol, and nonsteroidal anti-inflammatory drugs (NSAIDs) was reduced in all patients. The average reduction in chronic pain was over 70%.

CONCLUSION

This study demonstrates that treatment with Imatinib in patients with SCD or sickle cell anemia (SCA) may be a suitable therapeutic option for reducing painful crises.

Sickle cell disease and acute leukemia: one case report and an extensive review

Population-based studies and case reports suggest that there may be an increased risk of acute leukemia associated with sickle cell disease (SCD). Following the description of a new case report, an extensive review of the literature identified 51 previously described cases. Most cases study showed myelodysplastic features confirmed, when available, by genetic markers such as chromosome 5 and/or chromosome 7 abnormalities and TP53 gene mutations. The increased risk of leukemogenesis is certainly multifactorial and related to the pathophysiologic mechanisms of the clinical manifestations of SCD. Chronic hemolysis and secondary hemochromatosis may cause increased chronic inflammation, resulting in persistent marrow stress, which could potentially compromise the genomic stability of the hematopoietic stem cells generating genomic damage and somatic mutations over the course of SCD and its treatment, resulting in a clone that led to acute myeloid leukemia.

Incidence of cancer and related deaths in hemoglobinopathies: A follow-up of 4631 patients between 1970 and 2021

BACKGROUND

The correlation between thalassemia and malignancies other than hepatocellular carcinoma (HCC) and the possible relationship between other hemoglobinopathies and tumor risk have been poorly evaluated.

METHODS

Eight Italian specialized centers evaluated the incidence of malignant neoplasms in hemoglobinopathies as well as their sites and features. The study cohort included 4631 patients followed between 1970 and 2021 (transfusion-dependent β-thalassemia, 55.6%; non-transfusion-dependent thalassemia, 17.7%; sickle cell disease, 17.6%; hemoglobin H disease, 8.3%).

RESULTS

A total of 197 diagnoses of cancer were reported (incidence rate, 442 cases per 100,000 person-years). The liver was the most frequent site of tumors in both sexes, with a higher incidence (190 cases per 100,000 person-years) in comparison with the general population found in all types of hemoglobinopathies (except hemoglobin H disease). In recent years, tumors have become the second cause of death in patients with transfusion-dependent thalassemia. A lower risk of breast and prostate cancer was observed in the whole group of patients with hemoglobinopathies. The first cancer diagnoses dated back to the 1980s, and the incidence rate sharply increased after the 2000s. However, although the incidence rate of cancers of all sites but the liver continued to show an increasing trend, the incidence of HCC showed stability.

CONCLUSIONS

These findings provide novel insights into the relationship between cancer and hemoglobinopathies and suggest that the overall risk is not increased in these patients. HCC has been confirmed as the most frequent tumor, but advances in chelation and the drugs that have led to the eradication of hepatitis C may explain the recent steadiness in the number of diagnoses that is reported here.

Sickle Cell Disease in Children and Adolescents: A Review of the Historical, Clinical, and Public Health Perspective of Sub-Saharan Africa and Beyond

Sickle cell disease (SCD) is an umbrella term for a group of life-long debilitating autosomal recessive disorders that are caused by a single-point mutation (Glu→Val) that results in polymerization of hemoglobin (Hb) and reversible sickle-shape deformation of erythrocytes. This leads to increased hemolysis of erythrocytes and microvascular occlusion, ischemia-reperfusion injury, and tissue infarction, ultimately causing multisystem end-organ complications. Sickle cell anemia (HbSS) is the most common and most severe genotype of SCD, followed by HbSC, HbSβ⁰thalassemia, HbSβ+thalassemia, and rare and benign genotypes. Clinical manifestations of SCD occur early in life, are variable, and are modified by several genetic and environmental factors. Nearly 500 children with SCD continue to die prematurely every day, due to delayed diagnosis and/or lack of access to comprehensive care in sub-Saharan Africa (SSA), a trend that needs to be urgently reversed. Despite proven efficacy in developed countries, newborn screening programs are not universal in SSA. This calls for a consolidated effort to make this possible, through the use of rapid, accurate, and cheap point-of-care test kits which require minimal training. For almost two decades, hydroxyurea (hydroxycarbamide), a century-old drug, was the only disease-modifying therapy approved by the U.S. Food and Drug Administration. Recently, the list expanded to L-glutamine, crizanlizumab, and voxelotor, with several promising novel therapies in the pipeline. Despite its several limitations, hematopoietic stem cell transplant (HSCT) remains the only curative intervention for SCD. Meanwhile, recent advances in gene therapy trials offer a glimpse of hope for the near future, although its use maybe limited to developed countries for several decades.

Absence of hydroxyurea-induced mutational effects supports higher utilisation for the treatment of sickle cell anaemia

Hydroxyurea (hydroxycarbamide) is approved for treating both children and adults with sickle cell anaemia (SCA). Fetal haemoglobin (HbF) induction is the primary treatment response, along with improved anaemia, reduced haemolysis, myelosuppression and decreased endothelial inflammation. Hydroxyurea has proven clinical efficacy for SCA - treatment significantly reduces disease manifestations and prolongs survival. Despite these recognised benefits, long-standing concerns regarding the risks of mutagenic and potentially carcinogenic drug exposure have hampered efforts for broad hydroxyurea use in SCA, although these are based largely on outdated experimental models and treatment experiences with myeloproliferative neoplasms. Consequently, many patients with SCA are not receiving this highly effective disease-modifying therapy. In this review, we describe the concept of genotoxicity and its laboratory measurements, summarise hydroxyurea-associated data from both preclinical and clinical studies, and discuss carcinogenic potential. The genotoxicity results clearly demonstrate that hydroxyurea does not directly bind DNA and is not mutagenic. Rather, its genotoxic effects are limited to indirect clastogenicity occurring in select cell types, and only when high dose and time thresholds are exceeded. This absence of mutagenic activity is consistent with the observed lack of any compelling carcinogenic potential. Since hydroxyurea therapy for SCA carries minimal carcinogenic risks, the current drug labelling should be modified accordingly, and prescribing practices should be broadened to allow better access and increased utilisation of this highly effective drug.

Pediatric brain tumor care in a Sub-Saharan setting: current poise of a precariously loaded dice

OBJECTIVE

To evaluate the current status of pediatric brain tumor (PBT) care and identify determinants and profiles of survival and school attendance.

METHODS

An 8-year institution-based prospective longitudinal study. All cases investigated with neuroimaging and treated were enrolled. Data was analyzed with SPSS (Inc) Chicago IL, USA version 23. Chi Square test, One-way ANOVA and confidence limits were used to evaluate associations at the 95% level of significance. Ethical approval for our study was obtained Health Research Ethics Committee of our hospital.

RESULTS

Among 103 patients enrolled, 92 satisfied our study criteria. There were 45 males and 39 females, M: F = 0.8. The mean age was 9.5 ± 2.1 years 95%CI with a range of 7 months to 16 years. The most common symptom was headache for supratentorial lesions (73%) and gait disturbance (80.2%) for infratentorial lesions. More tumors were supratentorial in location 51 (55.4%), 35 (38.1%) were infratentorial and 6 (6.5%) were transtentorial. Craniopharyngiomas (n = 23), medulloblastomas (n = 22) and astrocytomas (n = 15) were the most common tumors. Hemoglobin genotype (AA and AS) had some influence on tumor phenotype FT, P = 0.033. 76 cases were microsurgically resected while 16 patients were treated with radiotherapy alone. The 30-day mortality for operated cases is 7.2 ± 0.7%. Overall 1-year and 5-year survival was 66.7 and 52.3%, respectively. School attendance, performance and outcome varied among treatment subgroups.

CONCLUSION

Survival profile in this series suggests some improvement in comparison to previous studies from our region, Hemoglobin genotype profiles may signature paediatric brain tumor phenotypes in our setting.

Sickle cell disease induces resistance to cutaneous carcinogenesis

Background

While skin carcinomas are reported in chronic ulcers and in patients treated with hydroxyurea (HU) for myeloproliferative neoplasms, no skin carcinoma has been reported in patients with sickle cell disease (SCD), presenting chronic skin ulcers or treated with HU. The objective was to estimate the risk of cutaneous malignant transformation in SCD patients with prolonged leg ulcers or under HU therapy.

Results

In this cross-sectional study, the cohort consisted of 1543 patients. In the first series, 29 patients presented a total of 53 ulcers lasting more than two years. The median age was 35 ± 8.4 years old. The median duration for a single ulcer was 9.2 ± 7 years. None of the examined ulcers showed any suspicious area of malignant transformation. In the second series, 187 patients treated with HU for more than two years were identified. The median age was 31.3 ± 9.9 years old. The median duration of treatment with HU was 6 ± 3.2 years. No skin carcinoma or actinic keratosis was recorded.

Conclusions

This study showed that skin carcinogenesis did not occur in our series of SCD patients exposed to transforming events such as long term HU treatment or prolonged leg ulcers.

Evaluation of hydroxyurea genotoxicity in patients with sickle cell disease

OBJECTIVE

To evaluate the induction of DNA damage in peripheral blood mononuclear cells of patients with sickle cell disease, SS and SC genotypes, treated with hydroxyurea.

METHODS

The study subjects were divided into two groups: one group of 22 patients with sickle cell disease, SS and SC genotypes, treated with hydroxyurea, and a Control Group composed of 24 patients with sickle cell disease who were not treated with hydroxyurea. Peripheral blood samples were submitted to peripheral blood mononuclear cell isolation to assess genotoxicity by the cytokinesis-block micronucleus cytome assay, in which DNA damage biomarkers - micronuclei, nucleoplasmic bridges and nuclear buds - were counted.

RESULTS

Patients with sickle cell disease treated with hydroxyurea had a mean age of 25.4 years, whereas patients with sickle cell disease not treated with hydroxyurea had a mean age of 17.6 years. The mean dose of hydroxyurea used by the patients was 12.8mg/kg/day, for a mean period of 44 months. The mean micronucleus frequency per 1,000 cells of 8.591±1.568 was observed in the Hydroxyurea Group and 10.040±1.003 in the Control Group. The mean frequency of nucleoplasmic bridges per 1,000 cells and nuclear buds per 1,000 cells for the hydroxyurea and Control Groups were 0.4545±0.1707 versus 0.5833±0.2078, and 0.8182±0.2430 versus 0.9583±0.1853, respectively. There was no statistically significant difference between groups.

CONCLUSION

In the study population, patients with sickle cell disease treated with the standard dose of hydroxyurea treatment did not show evidence of DNA damage induction.

Occurrence of acute myeloid leukemia in hydroxyurea-treated sickle cell disease patient

Hydroxyurea (HU) has been widely used in sickle cell disease. Its potential long-term risk for carcinogenesis or leukemogenic risk remains undefined. Here, we report a 26 y old African-American female with Sickle Cell Disease (SCD) who developed refractory/relapsed acute myeloid leukemia (AML) 6 months after 26 months of HU use. That patient's cytogenetics and molecular genetics analyses demonstrated a complex mutation profile with 5q deletion, trisomy 8, and P53 deletion (deletion of 17p13.1). P53 gene sequence studies revealed a multitude of somatic mutations that most suggest a treatment-related etiology. The above-mentioned data indicates that the patient may have developed acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) as a direct result of HU exposure.

Immunoglobulin A Myeloma in a Newly Diagnosed Sickle Cell Disease Patient

Several neoplasms including hematological malignancies occurring in very few patients with sickle cell syndromes have been reported in literature, particularly as survival among these patients and diagnostic accuracy have continued to improve. Multiple myeloma (MM) has rarely been reported in patients with hemoglobin (Hb) S + C. We report a 65-year-old retired banker who was recently diagnosed with HbS + C. This patient developed MM with markedly elevated erythrocyte sedimentation rate, mild anemia, 80% bone marrow plasmacytosis, and elevated serum immunoglobulin A level, while plain X-ray of the lumbosacral spine showed multilevel vertebral collapse.

Hydroxyurea (hydroxycarbamide) genotoxicity in pediatric patients with sickle cell disease

BACKGROUND

Hydroxyurea (HU) reduces the severity of sickle cell disease (SCD) in children; nevertheless, its long-term safety is an important concern. This paper evaluates HU genotoxicity at dose ≤ 30 mg/kg/day after over 2 years of treatment.

PROCEDURE

The study included 76 children: 32 SCD patients treated with HU, 27 SCD patients not treated with HU, and 17 unaffected children. HU patients were classified as good or poor responders according to their clinical response. Comet assay allows the comparison of DNA damage between both groups of patients and unaffected children. Maximal concentration (C_max ) of HU in plasma was determined after drug administration.

RESULTS

Mean values of DNA in the comet tail were 5.13 ± 6.84 for unaffected children, 5.80 ± 7.78 for patients with SCD treated with HU, and 5.61 ± 6.91 for patients with SCD not treated with HU. Significant differences were observed between unaffected children and children with SCD. No difference was evident between comets from SCD patients treated and not treated with HU. In the case of HU, mean DNA in the comet tail was significantly lower in good responders than in poor responders: 5.54 ± 7.77 and 6.69 ± 8.43, respectively. Mean C_max value on plasma was 39.08 ± 15.65 mg/l; N = 31.

CONCLUSIONS

SCD increases, slightly but significantly, DNA damage in lymphocytes from patients with SCD. Patients with SCD treated with HU do not present more nucleoid damage than patients with SCD not treated with HU. Good responders to the HU treatment have significantly less nucleoid damage than poor responders. HU treatment at ≤30 mg/kg/day does not expose patients to a genotoxic plasma concentration.

Sarcomatoid Renal Cell Carcinoma in an Adolescent with Sickle Cell Anaemia

Malignancies have been reported to occur in people with sickle cell disease. Renal medullary carcinoma (RMC), also tagged seventh sickle cell nephropathy, is an aggressive cancer seen almost exclusively in people with sickle cell disease with more than 160 cases reported worldwide, but only few cases were reported in patients with sickle cell anaemia (HBSS) and from Nigeria. Sarcomatoid renal cell carcinoma is a renal tumour of any histologic variant containing foci of high-grade malignant spindle cells. We report an adolescent girl with sickle cell anaemia (HBSS) who presented with left renal tumour, histology of which confirmed a diagnosis of sarcomatoid renal cell carcinoma (sRCC). Surgical debulking and palliative care with chemotherapy were given, and she demised 10 months after. The rarity of the case and challenges of managing a cancer in the background of a chronic haematologic disorder are highlighted.

Real-life experience with hydroxyurea in sickle cell disease: A multicenter study in a cohort of patients with heterogeneous descent

We conducted the first nation-wide cohort study of sickle cell disease (SCD) in Italy, a Southern European country exposed to intense recent flux migration from endemic areas for SCD. We evaluate the impact of hydroxyurea on a total of 652 pediatric and adult patients from 33 Reference Centers for SCD (mean age 24.5±15years, 51.4% males). Hydroxyurea median treatment duration was 7years (range: <1year to 29years) at a mean therapeutic dose of 18±4.7mg/kg/day. Hydroxyurea was associated with a significant increase in mean total and fetal hemoglobin and a significant decrease in mean hemoglobin S, white blood and platelet counts, and lactate dehydrogenase levels. Hydroxyurea was associated with a significant reduction in the incidence of acute chest syndrome (-29.3%, p<0.001), vaso-occlusive crisis (-34.1%, p<0.001), hospitalization (-53.2%, p<0.001), and bone necrosis (-6.9%, p<0.001). New silent cerebral infarction (SCI) occurred during treatment (+42.4%, p<0.001) but not stroke (+0.5%, p=0.572). These observations were generally consistent upon stratification for age, descent (Caucasian or African), genotype (βS/βS, βS/β⁰ or βS/β⁺) and duration of treatment (< or ≥10years). There were no new safety concerns observed compared to those commonly reported in the literature. Our study, conducted on a large population of patients with different descent and compound state supports the benefits of hydroxyurea therapy as a treatment option. Registered at clinical trials.gov (NCT02709681).

Risk of individual malignant neoplasms in patients with sickle cell disease: English national record linkage study

OBJECTIVE

Case reports suggest that there may be an increased risk of some cancers associated with sickle cell disease. However, population-based studies are scarce and there is no comprehensive enumeration of the risks across the whole range of site-specific cancers. Our aim was to provide this.

DESIGN

We used an English national dataset of linked statistical records of hospital admissions and deaths from 1999 to 2011 to undertake a retrospective cohort study.

SETTING

England.

PARTICIPANTS

Records of all hospital admissions in England with SCD or with conditions included in the control cohort.

MAIN OUTCOME MEASURES

Rate ratios were calculated comparing rates of cancer in a sickle cell disease cohort and a control cohort, confining the analyses to people whose ethnicity was recorded as Black.

RESULTS

Comparing the sickle cell disease cohort with the cohort without sickle cell disease, the rate ratio for all cancers combined was 2.1 (95% confidence interval 1.7-2.5). There were significantly high rate ratios for haematological malignancies, including Hodgkin's lymphoma (rate ratio 3.7, 1.5-8.4), non-Hodgkin's lymphoma (2.6, 1.3-4.8), multiple myeloma (5.5, 2.8-10.1), lymphoid leukaemia (3.3, 1.3-8.0) and myeloid leukaemia (10.0, 4.6-21.5). Four solid tumours showed elevated rate ratios: colon cancer (2.8, 1.2-5.5), non-melanoma skin cancer (4.4, 1.3-12.2), kidney cancer (5.4, 2.3-11.5) and thyroid cancer (5.1, 1.3-15.4).

CONCLUSIONS

The risk of some malignancies may be raised in patients with sickle cell disease. However, this study was based on administrative data without the scope to validate these against patients' full clinical records. Our findings need confirmation or refutation. If confirmed, work to elucidate, at the genetic and molecular level, why people with sickle cell disease have elevated risks of individual cancers might make contributions to the fundamental understanding of carcinogenesis.

Sickle Cells Abolish Melanoma Tumorigenesis in Hemoglobin SS Knockin Mice and Augment the Tumoricidal Effect of Oncolytic Virus In Vivo

Insights from the study of cancer resistance in animals have led to the discovery of novel anticancer pathways and opened new venues for cancer prevention and treatment. Sickle cells (SSRBCs) from subjects with homozygous sickle cell anemia (SCA) have been shown to target hypoxic tumor niches, induce diffuse vaso-occlusion, and potentiate a tumoricidal response in a heme- and oxidant-dependent manner. These findings spawned the hypothesis that SSRBCs and the vasculopathic microenvironment of subjects with SCA might be inimical to tumor outgrowth and thereby constitute a natural antitumor defense. We therefore implanted the B16F10 melanoma into humanized hemoglobin SS knockin mice which exhibit the hematologic and vasculopathic sequelae of human SCA. Over the 31-day observation period, hemoglobin SS mice showed no significant melanoma outgrowth. By contrast, 68-100% of melanomas implanted in background and hemoglobin AA knockin control mice reached the tumor growth end point (p < 0.0001). SS knockin mice also exhibited established markers of underlying vasculopathy, e.g., chronic hemolysis (anemia, reticulocytosis) and vascular inflammation (leukocytosis) that differed significantly from all control groups. Genetic differences or normal AA gene knockin do not explain the impaired tumor outgrowth in SS knockin mice. These data point instead to the chronic pro-oxidative vasculopathic network in these mice as the predominant cause. In related studies, we demonstrate the ability of the sickle cell component of this system to function as a therapeutic vehicle in potentiating the oncolytic/vasculopathic effect of RNA reovirus. Sickle cells were shown to efficiently adsorb and transfer the virus to melanoma cells where it induced apoptosis even in the presence of anti-reovirus neutralizing antibodies. In vivo, SSRBCs along with their viral cargo rapidly targeted the tumor and initiated a tumoricidal response exceeding that of free virus and similarly loaded normal RBCs without toxicity. Collectively, these data unveil two hitherto unrecognized findings: hemoglobin SS knockin mice appear to present a natural barrier to melanoma tumorigenesis while SSRBCs demonstrate therapeutic function as a vehicle for enhancing the oncolytic effect of free reovirus against established melanoma.

Anaplastic Ependymoma in a Child With Sickle Cell Anemia: A Case Report Highlighting Treatment Challenges for Young Children With Central Nervous System Tumors and Underlying Vasculopathy

A 3-year-old boy with sickle cell anemia (SCA) presented with progressive daily emesis and was found to have an anaplastic ependymoma. Radiation therapy and chemotherapy are usually employed after subtotal resections of anaplastic ependymomas, although the benefits from chemotherapy are unclear. To mitigate the risks of adjuvant treatment in this patient at risk for SCA-associated vasculopathy, renal impairment, and other end-organ damage, proton beam irradiation without chemotherapy was chosen. Scheduled packed red blood cell transfusions were instituted to maintain sickle hemoglobin levels less than 30%. This case highlights treatment complexities for malignant brain tumors in patients predisposed to treatment-related adverse effects.

Hydroxyurea therapy for sickle cell anemia

INTRODUCTION

Sickle cell anemia (SCA) is a severe, inherited hemoglobin disorder affecting 100,000 persons in the US and millions worldwide. Hydroxyurea, a once daily oral medication, has emerged as the primary disease-modifying therapy for SCA. The accumulated body of evidence over 30 years demonstrates that hydroxyurea is a safe and effective therapy for SCA, but hydroxyurea remains underutilized for a variety of reasons.

AREAS COVERED

In this review, we summarize the available evidence regarding the pharmacology, clinical, and laboratory benefits, and safety of hydroxyurea therapy for the treatment of SCA. The purpose of this review is to provide the reader a comprehensive understanding of hydroxyurea and to reinforce the fact that hydroxyurea is a safe and effective medication for the treatment of SCA.

EXPERT OPINION

In our opinion, hydroxyurea therapy should be considered standard-of-care for SCA, representing an essential component of patient management. Early initiation and broader use of hydroxyurea will alter the natural history of SCA, so affected children can live longer and healthier lives. In addition, hydroxyurea use should be extended to low-resource settings such as sub-Saharan Africa, where the burden of SCA and the need for hydroxyurea is arguably the greatest.

Evolving Therapeutic Options for Polycythemia Vera: Perspectives of the Canadian Myeloproliferative Neoplasms Group

Polycythemia vera (PV) is a clonal stem cell disorder characterized by erythrocytosis and associated with burdensome symptoms, reduced quality of life, risk of thrombohemorrhagic complications, and risk of transformation to myelofibrosis and acute myeloid leukemia. The discovery of the JAK2 V617 mutation marked a significant milestone in understanding the pathophysiology of the disease and subsequently the diagnostic and therapeutic approaches. The current diagnostic criteria for PV are based on hemoglobin level and presence of the JAK2 V617 mutation. The treatment is geared toward prevention of thrombotic events, normalization of blood counts, control of disease-related symptoms, and potential prolongation of survival. Cytoreductive therapy is indicated in patients at increased risk of thrombosis. Hydroxyurea (HU) remains the most commonly used first-line cytoreductive therapy and is superior to phlebotomy in reducing risk of arterial and venous thrombosis. Interferon (IFN) is used either at failure of HU or in selected patients as first-line therapy. The results of pegylated IFN in phase 2 studies appear encouraging, with molecular responses occurring in some patients. Ongoing phase 3 studies of HU versus pegylated IFN will define the optimal first-line cytoreductive therapy for PV. A recent phase 3 trial has shown the superiority of the JAK1/2 inhibitor ruxolitinib in comparison to best available treatment in HU-intolerant or -resistant patients. The therapeutic landscape of PV is likely to change in the near future. In this report, we assess the potential impact of the changing landscape of PV management on daily practice.

Therapy-Related Myeloid Neoplasms

OBJECTIVES

In the 2008 World Health Organization classification, cases of acute myeloid leukemia (AML) and myelodysplastic syndrome that arise after chemotherapy or radiation therapy for a primary neoplasm are considered together as therapy-related myeloid neoplasms (TR-MNs). This concept, however, is not universally accepted since there are confounding variables in attributing myeloid neoplasms to earlier therapies.

METHODS

Cases in session 6 of the 2013 Workshop of the Society for Hematopathology/European Association for Haematopathology illustrated myeloid neoplasms thought likely to be TR-MNs, and discussed the differences and biologic similarities with de novo myeloid neoplasms.

RESULTS

We reviewed data showing that diagnosis of TR-MN alters patient outcome only in specific subsets. The session also included examples of therapy-related AML with recurrent genetic abnormalities, such as t(15;17), inv(16), and t(8;21), and reports were highlighted showing that patients with these neoplasms have clinical outcomes similar to patients with their de novo counterparts.

CONCLUSIONS

The study of TR-MNs will likely provide insight into the pathogenesis of de novo myeloid disease and may explain why some patients with cancer develop TR-MN and evidently have a higher genetic susceptibility, whereas most patients treated with the same agents do not. These studies will also result in critical reappraisal of current concepts related to TR-MNs.

Melanoma tumor growth is accelerated in a mouse model of sickle cell disease

Background

The effect of sickle cell disease (SCD) on tumor growth is unknown. Sickled red blood cells may form aggregates within the microvasculature of hypoxic tumors and reduce blood flow leading to impairment of tumor growth. However, there is a paucity of data related to tumor growth in SCD.

Methods

To investigate the effect of SCD on tumor growth in a melanoma model, we generated SCD and control mice using bone marrow transplantation and inoculated the chest wall with B16-F10 melanoma cells. Tumor growth was monitored and angiogenesis was studied in vivo and in vitro.

Results

From day 1 to 21, tumor growth rate was nearly identical between SCD and WT mice, however from day 22 to day 29 tumor growth was accelerated in SCD mice compared to WT mice. Disparity in tumor size was confirmed at autopsy with an approximate 2-fold increase in tumor weights from SCD mice. Tumors from SCD mice showed increased vascularity and elevated levels of heme oxygenase-1 (HO-1). HO-1 inhibition with zinc protoporphyrin (ZnPP) blocked the angiogenic and tumor growth response to SCD in vivo and the response to hemin in vitro.

Conclusions

Growth of melanoma tumors is potentiated in a mouse model of SCD. Therapies targeting angiogenesis or HO-1 may be useful in SCD patients with malignant tumors.

Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Hydroxyurea (HU) is the most important advance in the treatment of sickle cell anaemia (SCA) for preventing complications and improving quality of life for patients. However, some aspects of treatment with HU remain unclear, including their effect on and potential toxicity to other blood cells such as neutrophils. This study used the measurement of Lactate Dehydrogenase (LDH) and Methyl ThiazolTetrazolium (MTT) and the comet assay to investigate the cytotoxicity and damage index (DI) of the DNA in the neutrophils of patients with SCA using HU.In the LDH and MTT assays, a cytoprotective effect was observed in the group of patients treated, as well as an absence of toxicity. When compared to patients without the treatment, the SS group (n=20, 13 women and 07 men, aged 18-69 years), and the group of healthy individuals (AA) used as a control group (n=52, 28 women and 24 men, aged 19-60 years), The SSHU group (n=21, 11 women and 10 men, aged 19-63 years) showed a significant reduction (p<0.001) in LDH activity and an increase in the percentage of viable cells by the MTT (p<0.001). However, the SSHU group presented significantly higher DI values (49.57±6.0 U/A) when compared to the AA group (7.43 ± 0,94U/A) and the SS group (22.73 ±5.58 U/A) (p<0.0001), especially when treated for longer periods (>20 months), demonstrating that despite the cytoprotective effects in terms of cell viability, the use of HU can induce DNA damage in neutrophils.

The association between tricuspid regurgitation velocity and 5-year survival in a North West London population of patients with sickle cell disease in the United Kingdom

Raised tricuspid regurgitant velocity (TRV) occurs in approximately 30% of adults with sickle cell disease (SCD), and has been shown to be an independent risk factor for death. TRV was assessed in 164 SCD patients who were subsequently followed up for survival. Raised pulmonary pressures were defined as a TRV jet ≥2.5 m/s on echocardiography. Elevated TRV was present in 29.1% of patients and it was associated with increased age and left atrial diameter. There were 15 deaths (9.1%) over a median of 68.1 months follow up; seven patients had increased TRV, and eight patients had a TRV<2.5 m/s. Higher TRV values were associated with a greater than 4-fold increased risk of death (Hazard Ratio: 4.48, 99% confidence interval 1.01-19.8), although we found a lower overall mortality rate than has been reported in previous studies. TRV was not an independent risk factor for death. We have confirmed the association between raised TRV and mortality in a UK SCD population whose disease severity appears to be less than that reported in previous studies. Further prospective studies are needed to more clearly characterize which patient factors modify survival in SCD patients with raised TRV.

Hydroxycarbamide: clinical aspects

Due to its oral route of administration and mild toxicity profile, as well as its potent laboratory and clinical effects, hydroxyurea (or hydroxycarbamide) has been the primary focus of fetal hemoglobin (HbF) induction strategies for the treatment of children with sickle cell anemia (SCA). When administered orally once a day, hydroxyurea treatment is very well tolerated with little short-term toxicity. Hydroxyurea has documented laboratory efficacy with increases in Hb and HbF; treatment also significantly reduces the number of painful episodes, acute chest syndrome, transfusions, and hospitalizations. Most young patients reach a maximum tolerated dose of hydroxyurea at 25-30 mg/kg/d, where they will achieve key laboratory thresholds (Hb ≥ 9 g/dL and HbF ≥ 20%) without excessive myelosuppression. Potential long-term toxicities continue to be of great concern and should be monitored in all patients with SCA who receive hydroxyurea therapy. To date, however, no increases in stroke, myelodysplasia, or carcinogenicity have been detected in SCA patient cohorts, with drug exposure now reaching 15 years for some treated children. Taken together, available evidence suggests that hydroxyurea represents an inexpensive and effective treatment option that should be offered to most, if not all, patients with SCA. As countries in Africa develop newborn screening programs to identify SCA, the widespread use of hydroxyurea may prove to be a useful treatment to help ameliorate the disease in resource-limited settings. Hydroxyurea is the only currently available disease-modifying therapy for SCA, and is emerging as a safe and effective treatment for all patients with SCA, in both developed and developing countries.

Two assays to evaluate potential genotoxic effects of hydroxyurea in sickle cell disease patients

Hydroxycarbamide, well known in clinical settings as hydroxyurea (HU), is an antineoplastic agent inhibiting the ribonucleotide reductase enzyme, and thus, the conversion of ribonucleotides into deoxyribonucleotides. A concern about long term side effects of HU treatment in sickle cell disease patients, particularly genotoxicity, has often been evoked. The present study assessed two suitable methods to evaluate oxidative DNA damage associated with HU: the comet assay on blood lymphocytes and the quantification of urinary excretion of 8-oxodeoxyguanosine (8-oxodG). Both methods were applied in a preliminary study including seven sickle cell disease patients treated with HU, seven untreated sickle cell disease patients and five healthy volunteers. Concerning DNA damage, the comet assay and the 8-oxodG assay did not reveal any significant differences among the three groups. Methodologies used in this pilot study could be suitable to carry out further research in this area including a larger size sample setting.

Two cases of pediatric essential thrombocythemia managed effectively with hydroxyurea

Thrombocytosis is common in infancy and childhood. Essential thrombocythemia (ET), a myeloproliferative disorder, is a much less common cause of thrombocytosis in childhood. We report two cases of essential thrombocythemia in 5- and 10-year-old children, who presented with platelet counts of more than 1,000,000/mm(3). Treatment is not recommended for ET in an asymptomatic patient in the absence of bleeding or thrombosis and a platelet count <1,500,000/mm(3). Our first case had platelets >1,500,000/mm(3), and a second child was symptomatic with recurrent headache. Both responded well to therapy with hydroxyurea (dose 15-30 mg/kg/day) and tolerated it well.

Development of myelodysplastic syndrome and acute myeloid leukemia 15 years after hydroxyurea use in a patient with sickle cell anemia

We report a 41 year old male with sickle cell disease who developed a myelodysplastic syndrome and acute myeloid leukemia with complex karyotype involving chromosomes 5, 7 and 17 after 15 years of hydroxyurea treatment. He responded poorly to induction chemotherapy with cytarabine/idarubicin followed by high dose cytarabine and succumbed to neutropenic sepsis. Multiple systematic reviews, observational studies and clinical trials were conducted to identify the toxicity profile of hydroxurea. Only six cases of leukemia/myelodysplastic syndrome were identified in patients with sickle cell anemia treated with hydroxyurea. Subsequently, it was concluded that hydroxyurea is not leukemogenic. However, it was noted that most of the published studies had only up to 9 years of follow-up. Our patient was started on hydroxyurea in 1990, before the widespread use of the drug and took hydroxyurea for 15 years. His presentation may reflect an outcome otherwise not yet observed because of the short follow-up of prior studies. We believe that the leukemogenic risk of hydroxyurea should be discussed with the patients and their families. Studies evaluating the adverse effects of hydroxyurea should have longer follow-up before definitive conclusions are drawn.

Current strategies for the management of children with sickle cell disease

Children with sickle cell disease may present to doctors anywhere in the world. In developed countries, neonatal screening allows early identification and management of the disease, mostly through daily antibioprophylaxis, immunizations and education of the parents. Stroke prevention relies on the detection of high-risk patients by annual transcranial Doppler ultrasonography from 2 to 16 years of age. Annual check-ups aim to detect early organ deficiencies. The most frequent complications are pain, infections and acute anemia; they may occur in combination. Approximately 10% of children have severe sickle cell disease that may require chronic blood transfusion, hydroxyurea or hematopoietic stem cell transplantation. Comprehensive management programs have dramatically increased survival, and most patients now reach adulthood.

How I use hydroxyurea to treat young patients with sickle cell anemia

Hydroxyurea has many characteristics of an ideal drug for sickle cell anemia (SCA) and provides therapeutic benefit through multiple mechanisms of action. Over the past 25 years, substantial experience has accumulated regarding its safety and efficacy for patients with SCA. Early proof-of-principle studies were followed by prospective phase 1/2 trials demonstrating efficacy in affected adults, then adolescents and children, and more recently infants and toddlers. The phase 3 National Heart, Lung and Blood Institute-sponsored Multicenter Study of Hydroxyurea trial proved clinical efficacy for preventing acute vaso-occlusive events in severely affected adults. Based on this cumulative experience, hydroxyurea has emerged as an important therapeutic option for children and adolescents with recurrent vaso-occlusive events; recent evidence documents sustained long-term benefits with prevention or reversal of chronic organ damage. Despite abundant evidence for its efficacy, however, hydroxyurea has not yet translated into effective therapy for SCA. Because many healthcare providers have inadequate knowledge about hydroxyurea, patients and families are not offered treatment or decline because of unrealistic fears. Limited support for hydroxyurea by lay organizations and inconsistent medical delivery systems also contribute to underuse. Although questions remain regarding its long-term risks and benefits, current evidence suggests that many young patients with SCA should receive hydroxyurea treatment.

Hydroxyurea for children with sickle cell disease

Hydroxyurea therapy offers promise for ameliorating the clinical course of children with sickle cell disease (SCD). Hydroxyurea is a prototypic therapeutic option; it can be administered with minimal side effects, has a relatively wide therapeutic window, and has mechanisms of action that address pathophysiologic pathways of sickling, vaso-occlusion, hemolysis, and organ damage. There are limited data regarding hydroxyurea's ability to prevent or diminish organ dysfunction, and the long-term risks of hydroxyurea therapy remain incompletely defined. Although clinical trials are underway to address long-term issues, hydroxyurea remains an effective but underutilized therapy for SCD.

Cardiopulmonary complications leading to premature deaths in adult patients with sickle cell disease

Sickle cell disease (SCD) is associated with early mortality. We sought to determine the incidence, cause, and risk factors for death in an adult population of patients with SCD. All patients aged >/=18 years seen at the Adult Sickle Cell Center at Duke University Medical Center between January 2000 and April 2005 were enrolled. Forty-three patients (21 males and 22 females) died during the study period. The median age of survival was 39 years for females (95% CI: 34-56), 40 years for males (95% CI: 34-48), and 40 years overall (95% CI: 35-48). Cardiac causes of death accounted for 25.6% (11/43 patients); pulmonary, 14.0% (six patients); other SCD related, 32.6% (14 patients); unknown, 14.0% (six patients); and others, 14.0% (six patients). Pulseless electrical activity arrest, pulmonary emboli, multiorgan failure, and stroke were the most frequent causes of death. Among the deceased patients, the most common premorbid conditions were cardiopulmonary: acute chest syndrome/pneumonia (58.1%), Pulmonary hypertension (pHTN; 41.9%), systemic HTN (25.6%), congestive heart failure (25.6%), myocardial infarction (20.9%), and arrhythmias (14.0%). Tricuspid regurgitant jet velocity was significantly higher (3.1 m/sec vs. 2.6 m/sec, P < 0.001) and hemoglobin significantly lower (8.3 g/dL vs. 9.2 g/dL, P < 0.05) in deceased patients when compared with patients who lived, respectively. With improved preventive and therapeutic advances, including hydroxyurea therapy, acute complications such as infection are no longer the leading cause of death; instead, causes of death and premorbid conditions are shifting to chronic cardiopulmonary complications. Further, arrhythmia leading to premature death is under-recognized in SCD and warrants further investigation.

Transfusion of sickle cells may be a therapeutic option for patients suffering metastatic disease

Red blood cells from patients with sickle cell disease will sickle under conditions of hypoxemia and acidosis which is a similar milieu found in malignant tumors. While control of tumor angiogenesis has long been a goal of cancer therapy, selective occlusion of tumor blood supply may be achieved by transfusion of sickle cells into patients who suffer metastatic cancer. Although this potential therapy has not been previously reported in the medical literature, the concept may have been elusive to medical mainstream thinking because it requires transfusion of diseased cells. For this therapy to be effective, other environmental factors may need to be manipulated such inducing mild hypoxemia or hypercarbia (respiratory acidosis) to induce red cell sickling. Preliminary evidence supportive of this therapeutic approach to cancer treatment is provided by case evidence that sickle cell occlusion of a malignant brain tumor (glioma) produced tumor necrosis. Also sickle cells have been successfully transfused into primates. Furthermore, donor blood is crossmatched and transfused into patients suffering from sickle cell disease regularly in clinics and this procedure is associated with acceptable morbidity. Most importantly, animal models of sickle cell disease and cancer currently exist, and this theory could be tried with available technologies including ultrasound detection of vaso-occlusion. While the proposed therapy may not cure metastatic cancer, this treatment could prove useful for decreasing the size and perhaps the pain from metastatic tumor burden. Therefore, it is hypothesized that ABO Rh compatible crossmatched sickle cells transfused into patients who suffer metastatic cancer under controlled conditions of blood oxygenation and pH will selectively produce vaso-occlusive infarcts in malignant tumors and be a useful therapy. The author hopes for further investigations.

Malignancies in patients with beta-thalassemia major and beta-thalassemia intermedia: a multicenter study in Iran

BACKGROUND

Beta thalassemia is one of the most common genetic disorders in the world. The aim of this study was to determine the frequency, characteristics, and pattern of malignancies in patients with beta thalassemia major (BTM) and beta thalassemia intermedia (BTI) in Iran.

METHODS

We conducted a multicenter study via a retrospective chart review of patients with BTM and BTI between 2002 and 2007 in four thalassemia centers in Iran. A total of 4,630 records of patients with thalassemia were evaluated. Statistical analyses were done with SPSS software v. 15. P-values <0.05 were considered significant.

RESULTS

We detected 11 patients with beta thalassemia who also had malignant disease. Five patients (45.4%) were diagnosed with lymphoma and five with leukemia. The proportion of patients with cancer was higher in those with BTI. Cancer was diagnosed in patients with thalassemia aged 0-39 years, but not in any of the older patients. In patients with thalassemia overall and in patients with BTI, the highest age-specific rate of cancer incidence was seen in children <10 years old, whereas in the BTM group the highest incidence was observed in patients 20-29 years old. There were no statistically significant differences between patients with BTM and BTI and cancer regarding age, sex, splenectomy, hemoglobin, ferritin level, or malignancy type.

CONCLUSION

The coexistence of malignancy and beta thalassemia is not rare. Any alarming signs and symptoms including worsening anemia, splenomegaly, or lymphadenopathy should be a motive for concern because these symptoms may signal malignant disease.

The effect of prolonged administration of hydroxyurea on morbidity and mortality in adult patients with sickle cell syndromes: results of a 17-year, single-center trial (LaSHS)

The aim of this prospective study was to evaluate the long-term efficacy and safety of hydroxyurea (HU) in patients with sickle cell disease (SCD). Thirty-four patients with sickle cell anemia (hemoglobin S [HbS]/HbS), 131 with HbS/beta(0)-thal, and 165 with HbS/beta(+)-thal participated in this trial. HU was administered to 131 patients, whereas 199 patients were conventionally treated. The median follow-up period was 8 years for HU patients and 5 years for non-HU patients. HU produced a dramatic reduction in the frequency of severe painful crises, transfusion requirements, hospital admissions, and incidence of acute chest syndrome. The probability of 10-year survival was 86% and 65% for HU and non-HU patients, respectively (P = .001), although HU patients had more severe forms of SCD. The 10-year probability of survival for HbS/HbS, HbS/beta (0)-thal, and HbS/IVSI-110 patients was 100%, 87%, and 82%, respectively, for HU patients and 10%, 54%, and 66%, for non-HU patients. The multivariate analysis showed that fetal hemoglobin values at baseline and percentage change of lactate dehydrogenase between baseline and 6 months were independently predicted for survival in the HU group. These results highlight the beneficial effect of HU, which seems to modify the natural history of SCD and raise the issue of expanding its use in all SCD patients.

Advances in the use of hydroxyurea

Clinical experience with hydroxyurea for patients with sickle cell disease (SCD) has been accumulating for the past 25 years. The bulk of the current evidence suggests that hydroxyurea is well-tolerated, safe, and efficacious for most patients with SCD. Hydroxyurea has proven clinical efficacy for reducing acute vaso-occlusive events including pain episodes and acute chest syndrome. Salutary effects on hematological parameters include increases in fetal hemoglobin (HbF), hemoglobin, and MCV; also significant decreases occur in WBC, ANC, reticulocytes, LDH, and bilirubin. Treatment with hydroxyurea is usually considered for patients with recurrent vaso-occlusive events, but additional indications for treatment may include laboratory markers of disease severity and evidence of chronic organ dysfunction. Ten years ago, the US Food and Drug Administration approved hydroxyurea for adult patients with clinically severe SCD; however, its use in children remains off-label. Despite the large body of evidence regarding its efficacy and safety, hydroxyurea is currently prescribed only sparingly for patients with SCD and therefore has only limited effectiveness for this disorder; barriers to its use need to be identified and overcome.

Hydroxyurea for sickle cell disease: a systematic review for efficacy and toxicity in children

CONTEXT

Hydroxyurea is the only approved medication for the treatment of sickle cell disease in adults; there are no approved drugs for children.

OBJECTIVE

Our goal was to synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea in children with sickle cell disease.

METHODS

Medline, Embase, TOXLine, and the Cumulative Index to Nursing and Allied Health Literature through June 2007 were used as data sources. We selected randomized trials, observational studies, and case reports (English language only) that evaluated the efficacy and toxicity of hydroxyurea in children with sickle cell disease. Two reviewers abstracted data sequentially on study design, patient characteristics, and outcomes and assessed study quality independently.

RESULTS

We included 26 articles describing 1 randomized, controlled trial, 22 observational studies (11 with overlapping participants), and 3 case reports. Almost all study participants had sickle cell anemia. Fetal hemoglobin levels increased from 5%-10% to 15%-20% on hydroxyurea. Hemoglobin concentration increased modestly (approximately 1 g/L) but significantly across studies. The rate of hospitalization decreased in the single randomized, controlled trial and 5 observational studies by 56% to 87%, whereas the frequency of pain crisis decreased in 3 of 4 pediatric studies. New and recurrent neurologic events were decreased in 3 observational studies of hydroxyurea compared with historical controls. Common adverse events were reversible mild-to-moderate neutropenia, mild thrombocytopenia, severe anemia, rash or nail changes (10%), and headache (5%). Severe adverse events were rare and not clearly attributable to hydroxyurea.

CONCLUSIONS

Hydroxyurea reduces hospitalization and increases total and fetal hemoglobin levels in children with severe sickle cell anemia. There was inadequate evidence to assess the efficacy of hydroxyurea in other groups. The small number of children in long-term studies limits conclusions about late toxicities.