Unswitched memory B cell deficiency in children with sickle cell disease and response to pneumococcal polysaccharide vaccine

Early mortality in sickle cell disease (SCD) is attributed to increased infections due to loss of splenic function. Marginal zone B cells are important for initial opsonization of pathogens and can be absent in spleen histopathology in SCD. The frequency of unswitched memory B cells (UMBC), the circulating correlate of marginal zone B cells, reflects the immunologic function of the spleen. We hypothesized that asplenia in SCD is associated with alterations in the peripheral blood lymphocyte population and explored whether UMBC deficiency was associated with a clinical phenotype. We analyzed B cell subsets and clinical history for 238 children with SCD and 63 controls. The median proportion of UMBCs was lower in children with SCD compared with controls (4.7% vs. 6.6%, p < .001). Naïve B cells were higher in SCD compared with controls (80.6 vs. 76.3%, respectively, p = .02). UMBC frequency declined by 3.4% per year increase in age in SCD (95% CI: 2%, 4.7%, p < .001), but not in controls. A majority of children in all cohorts had an IgM concentration in the normal range for age and there were no differences between groups (p = .13). Subjects developed titers adequate for long-term protection to fewer serotypes in the polysaccharide vaccine than controls (14.7 vs. 19.4, p < .001). In this cohort, bacteremia was rare and specific clinical complications were not associated with UMBC proportion. In summary, UMBC deficiency occurs in SCD and is associated with age. Future studies should investigate B cell subsets prospectively and identify the mechanism of B cell loss in the spleen.

Expert consensus on the management of infusion-related reactions (IRRs) in patients with sickle cell disease (SCD) receiving crizanlizumab: a RAND/UCLA modified Delphi panel

Crizanlizumab, a monoclonal antibody against P-selectin, has been shown to reduce vaso-occlusive crises (VOCs) compared to placebo in patients ≥ 16 years with sickle cell disease (SCD). However, there have been rare reports of patients experiencing severe pain and subsequent complications within 24 hours of crizanlizumab infusions. These events are defined as infusion-related reactions (IRRs). Informed by current literature and clinical experience, a group of content experts developed clinical guidelines for the management of IRRs in patients with SCD. We used the RAND/University of California, Los Angeles (UCLA) modified Delphi panel method, a valid, reproducible technique for achieving consensus. We present our recommendations for managing IRRs, which depend on patient characteristics including: prior history of IRRs to other monoclonal antibodies or medications, changes to crizanlizumab infusion rate and patient monitoring, pain severity relative to patient's typical SCD crises, and severe allergic symptoms. These recommendations outline how to evaluate and manage IRRs in patients receiving crizanlizumab. Future research should validate this guidance using clinical data and identify patients at risk for these IRRs.

Ketamine for Pain in Sickle Cell Disease Reduces Opioid Usage

CONTEXT

Pain attributable to sickle cell disease (SCD) is often unpredictable, recurrent, and requires complex treatments. Subanesthetic ketamine infusion has been studied in other diseases and disorders, but there is still limited data on its efficacy in pain management for SCD.

OBJECTIVES

The primary objective is to determine if subanesthetic ketamine infusion reduces pain scores and opioid requirements in hospitalized pediatric patients with SCD.

RESULTS

Forty-six admissions among 22 patients between February 2018 and December 2019 were analyzed. We observed decrease in pain scores within 24 hours of ketamine initiation in 34 of 46 admissions (mean pain score per patient before ketamine initiation: 2.2-9.7, mean pain score per patient after ketamine initiation: 0-9.7; P < .05). We observed a decrease in pain scores in the remaining 12 admissions after greater than 24 hours of ketamine initiation. Opioid usage declined after ketamine infusion, with a difference of means in oral morphine equivalents before and after ketamine of 122.8 mg/day. The side effects observed with ketamine infusion included hallucinations in 11 (23.9%) admissions. Only four (8.7%) admissions required cessation of the infusion due to side effects. The readmission rate at two weeks and four weeks after first ketamine infusion was the same (12.5%) at both time points. For all patients in the cohort, the introduction of ketamine into pain regimens did not reduce the number of admissions in the year following ketamine initiation relative to the year prior.

CONCLUSION

In pediatric patients with SCD, subanesthetic ketamine was safe as a continuous infusion and effectively reduced both pain scores and opioid requirements.

New ASH initiatives to improve patient care in the long-overlooked sickle cell disease

Because of the unique biology of sickle cell disease (SCD) as well as the societal disadvantages and racial inequities suffered by these patients, individuals with SCD have not benefited from the same remarkable advances in care and therapeutics as those with other hematologic disorders. Life expectancy of individuals with SCD is shortened by ∼20 years even with optimal clinical care, and infant mortality continues to be a major concern in low-income countries. As hematologists, we must do more. The American Society of Hematology (ASH) and the ASH Research Collaborative have instituted a multipronged initiative to improve the lives of individuals living with this disease. Here, we describe 2 components of this ASH initiative, the Consortium on Newborn Screening in Africa (CONSA) to improve the early diagnosis of infants in low-resource countries and the SCD Clinical Trial Network to accelerate the development of more effective therapeutics and care for those with this disorder. The combination of SCD-focused initiatives, ASH Research Collaborative, CONSA, and Sickle Cell Clinical Trials Network has enormous potential to dramatically alter the course of SCD worldwide. We believe that the timing is ripe to embark on these critical and worthwhile initiatives and improve the lives of individuals with this disease.

Unique Hemoglobinopathy Pattern Following Treatment with Voxelotor

OBJECTIVE

Voxelotor, a FDA-approved drug for the treatment of patients with sickle cell disease (SCD), inhibits hemoglobin S (HbS) polymerization and increases total hemoglobin via hemolysis reduction. This drug has shown unique patterns in hemoglobin fractionation, affecting its interpretation. We aimed to evaluate whether these voxelotor-induced changes can be linked to improvement of hemolysis markers in pediatric patients on voxelotor.

METHODS

A total of 15 patients (age 12 to 20 years; 40% females) on voxelotor were evaluated to compare changes in the hemoglobin fractionation by capillary electrophoresis, total hemoglobin, reticulocyte percentage (retic%), lactate dehydrogenase (LDH), and bilirubin measurements before and after the recorded date of voxelotor prescription.

RESULTS

Hemoglobin fractionation showed changes in the profile of 60% (9/15) of the patients studied. Out of the 9 patients for which voxelotor showed changes in the hemoglobin fractionation, 44% (4/9) had an increase of >1 g/dL in their total hemoglobin after voxelotor treatment was started. Assessment of other hemolysis markers available showed decreased LDH (4/4), retic % (6/8), and bilirubin (3/4).

CONCLUSIONS

Unique pattern of hemoglobin fractionation analysis following therapy with voxelotor has potential as a tool for the assessment of response and/or compliance to voxelotor for the treatment of SCD.

Multi-center retrospective study of children with sickle cell disease admitted to pediatric intensive care units in the United States

Data on outcomes and interventions for children with sickle cell disease (SCD) admitted to a pediatric intensive care units (PICU) are unknown. We provide the first comprehensive multi-center report on PICU interventions associated with death, the need for invasive respiratory support or stroke among critically ill children with SCD. We collected retrospective multi-center cohort data from January 1, 2012 to December 31, 2019 utilizing the Virtual Pediatric Systems, LLC database. We identified 3388 unique children with SCD, accounting for a total of 5264 PICU admissions from 138 PICUs. The overall mortality rate for the PICU admissions cohort was 1.8% (95/5264 PICU admissions, 95/3388 [2.8%] of all unique patients), the rate of needing of needing Invasive Respiratory Support (IRS, a composite category of exposure) was 21.3% (872/4093 PICU admissions with complete data) and the overall rate of stroke (ischemic or hemorrhagic) was 12.5% (657/5264 PICU admissions). In multivariable analysis adjusting for admission age category, sex, race/ethnicity, PRISM-3 score at admission, exposure to IRS, quartile of unit volume of patients with SCD, and patient origin, admitted children who needed invasive respiratory support (IRS) had higher adjusted odds ratios for mortality (adjusted odds ratio [aOR], 19.72; 95% confidence interval [CI] 8.98-43.29; p < 0.001), although admitted children > 2 years old had decreased aOR for needing IRS (aOR 0.25-0.62; 95% CI 0.16-0.94; p < 0.001-0.025). By contrast, admitted children > 2 years old had a strikingly increased aOR for stroke (aOR 7.57-16.32; 95% CI 2.25-52.15; p < 0.001). These groups may represent PICU-specific subsets of patients with SCD who are at higher risk for more serious illness and should deserve early consideration for referral to a pediatric institution providing comprehensive care for patients with SCD.

Determinants of retention in care of newborns diagnosed with sickle cell disease in Liberia: Results from a mixed-methods study of caregivers

High-income nations have established that early diagnosis and preventive treatment reduces early deaths in sickle cell disease (SCD). However, in low-/middle-income countries where SCD is common, attrition from clinical care is common. Reasons for poor retention in care are multi-factorial and poorly understood. The objective of this study was to identify factors that influence caregiver decision-making around chronic health care needs of a child with SCD. We conducted an exploratory sequential mixed methods study of caregivers of children diagnosed with SCD during a newborn screening program in Liberia. Caregivers completed questionnaires and semi-structured interviews designed to identify drivers of health decision-making. Interviews were digitally recorded, transcribed, coded, and analyzed using semi-structured thematic analysis to identify themes. Data integration occurred by using quantitative results to expand and clarify the qualitative themes. Twenty-six caregivers participated in the study. The mean age of the child at the interview was 43.7 months. Five themes influencing health decisions were identified: grief, the importance of support networks, stigma, perceived benefits, and the burden of chronic disease. The five themes crossed multiple domains of a socioecological model and identified complex interactions between family, community, social and cultural norms, and organizational structures. This study highlights the importance of community awareness of SCD and appropriate health communication by healthcare workers. Healthcare decision-making is multifactorial and complex. These results provide a framework for improving retention in care. In a low-resource country such as Liberia, much can be done by leveraging existing resources and cultural practices.

Global perspectives on cellular therapy for children with sickle cell disease

PURPOSE OF REVIEW

Low-income and middle-income countries (LMICs), primarily in sub-Saharan Africa (SSA), predominantly experience the burden of sickle cell disease (SCD). High frequency of acute and chronic complications leads to increased utilization of healthcare, which burdens fragile health systems. Mortality for children with limited healthcare access remains alarmingly high. Cellular based therapies such as allogeneic hematopoietic stem cell transplant (HSCT) are increasingly used in resource-rich settings as curative therapy for SCD. Broad access to curative therapies for SCD in SSA would dramatically alter the global impact of the disease.

RECENT FINDINGS

Currently, application of cellular based therapies in LMICs is limited by cost, personnel, and availability of HSCT-specific technologies and supportive care. Despite the challenges, HSCT for SCD is moving forward in LMICs. Highly anticipated gene modification therapies have recently proven well tolerated and feasible in clinical trials in resource-rich countries, but access remains extremely limited.

SUMMARY

Translation of curative cellular based therapies for SCD should be prioritized to LMICs where the disease burden and cost of noncurative treatments is high, and long-term quality of life is poor. Focus on thoughtful modifications of current and future therapies to meet the need in LMICs, especially in SSA, will be especially impactful.

Indications for transfusion in the management of sickle cell disease

The transfusion of red blood cells (RBCs) is a crucial treatment for sickle cell disease (SCD). While often beneficial, the frequent use of transfusions is associated with numerous complications. Transfusions should be offered with specific guidelines in mind. Here we present updates to the indications for transfusion of RBCs in SCD. We review recent publications and include expert perspectives from hematology and transfusion medicine. For some clinical indications, such as ischemic stroke, the role of transfusion has been well studied and can be applied almost universally. For many other clinical scenarios, the use of transfusion therapy has less conclusive data and therefore must be tailored to individual needs. We highlight the roles of RBC transfusions in preventing or mitigating neurological disease, in reducing perioperative complications, in managing acute chest syndrome, and in optimizing pregnancy outcomes in SCD. We further highlight various transfusion techniques and when each might be considered. Potential complications of transfusion are also briefly discussed.

Allele-Specific Recombinase Polymerase Amplification to Detect Sickle Cell Disease in Low-Resource Settings

Sickle cell disease (SCD) is a group of common, life-threatening disorders caused by a point mutation in the β globin gene. Early diagnosis through newborn and early childhood screening, parental education, and preventive treatments are known to reduce mortality. However, the cost and complexity of conventional diagnostic methods limit the feasibility of early diagnosis for SCD in resource-limited areas worldwide. Although several point-of-care tests are commercially available, most are antibody-based tests, which cannot be used in patients who have recently received a blood transfusion. Here, we describe the development of a rapid, low-cost nucleic acid test that uses real-time fluorescence to detect the point mutation encoding hemoglobin S (HbS) in one round of isothermal recombinase polymerase amplification (RPA). When tested with a set of clinical samples from SCD patients and healthy volunteers, our assay demonstrated 100% sensitivity for both the β^A globin and β^S globin alleles and 94.7 and 97.1% specificities for the β^A globin allele and β^S globin allele, respectively (n = 91). Finally, we demonstrate proof-of-concept sample-to-answer genotyping of genomic DNA from capillary blood using an alkaline lysis procedure and direct input of diluted lysate into RPA. The workflow is performed in <30 min at a cost of <$5 USD on a commercially available benchtop fluorimeter and an open-source miniature fluorimeter. This study demonstrates the potential utility of a rapid, sample-to-answer nucleic acid test for SCD that may be implemented near the point of care and could be adapted to other disease-causing point mutations in genomic DNA.

Fever Management in Sickle Cell Disease in Low- and Middle-Income Countries: A Survey of SCD Management Programs

Management of fever is a key element of care for children with sickle cell disease (SCD). There exist few studies of current practices in managing fevers in SCD in low- and middle-income countries (LMICs) and malaria-endemic regions where SCD is prevalent. We surveyed medical providers in these settings to characterize current practices in infection prevention and fever management for children with SCD. We found wide variation in use of newborn screening for early diagnosis and infection prevention, pneumococcal vaccination, use of antibiotics and antimalarials, and route of antibiotic administration. Counter to established guidelines, 78% (95% CI: 59-100%) of respondents would consider using oral antibiotics for a febrile child with SCD. Only 17% (95% CI: 0-37%) would administer antibiotics to a well-appearing child with a positive malaria test. Availability of blood cultures did not affect duration of antibiotic course. Further study and standardization of fever management in SCD in LMICs are urgently needed.

Clinical and laboratory outcomes following total or partial splenectomy in patients with hereditary spherocytosis

This study compared outcomes following total (TS) or partial splenectomy (PS) among patients with hereditary spherocytosis. Seventy-nine patients (TS = 33, PS = 46) were identified. The follow-up period was longer after PS (59.6 vs. 24.9 months, p < .001). Long-term adverse events occurred more frequently following PS (50% vs. 29%, p = .001). Anemia, jaundice, and fatigue recurred in six patients with PS, leading to five completion splenectomies. Hemoglobin was not different between PS and TS by 5 years post-procedure (12.3 vs. 13.4 g/dL, p = .25). Both PS and TS ameliorate symptoms and improve hematologic parameters. The rate of secondary surgery following PS should be considered when planning the initial surgical procedure.

Turf wars: exploring splenomegaly in sickle cell disease in malaria-endemic regions

Sickle cell disease (SCD) is a group of recessively inherited disorders of erythrocyte function that presents an ongoing threat to reducing childhood and adult morbidity and mortality around the world. While decades of research have led to improved survival for SCD patients in wealthy countries, survival remains dismal in low- and middle-income countries. Much of the early mortality associated with SCD is attributed to increased risk of infections due to early loss of splenic function. In the West, bacterial infections with encapsulated organisms are a primary concern. In sub-Saharan Africa, where the majority of infants with SCD are born, the same is true. However malaria presents an additional threat to survival. The search for factors that define variability in sickle cell phenotypes should include environmental modifiers, such as malaria. Further exploration of this relationship could lead to novel strategies to reduce morbidity and mortality attributable to infections. In this review, we explore the interactions between SCD, malaria and the spleen to better understand how splenomegaly and splenic (dys)function may co-exist in patients with SCD living in malaria-endemic areas.

Acute lymphoblastic leukemia in a patient with MonoMAC syndrome/GATA2 haploinsufficiency

Patients with GATA2 haploinsufficiency have a significant predisposition to developing cytopenias, unique infectious manifestations, and myelodysplastic syndrome/acute myeloid leukemia (MDS/AML). We report a unique case of a patient who presented with B-cell acute lymphoblastic leukemia (B-ALL) and was subsequently diagnosed with monocytopenia and mycobacterium avium complex (MonoMAC) syndrome/GATA2 haploinsufficiency. The development of MDS/AML in patients with GATA2 haploinsufficiency is well described, however, the development of ALL has not been reported in the literature. ALL may be associated with GATA2 haploinsufficiency. Clinicians should be attuned to the features of the MonoMAC syndrome in patients with ALL that would prompt additional testing and alter treatment.

Newborn Screening for Sickle Cell Disease in Liberia: A Pilot Study

BACKGROUND

In malaria-endemic countries in West Africa, sickle cell disease (SCD) contributes to childhood mortality. Historically, Liberia had regions wherein hemoglobin S and beta-thalassemia trait were mutually exclusive. Data on hemoglobinopathies in the Monrovia, the capital, are outdated and do not reflect urban migration. Updating the epidemiology of SCD is necessary to plan a public health and clinical agenda. Neither newborn screening (NBS) nor screening tools were available in country. This pilot study aimed to determine the feasibility of NBS using a South-South partnership and define the incidence of sickle cell trait (SCT) and SCD in Monrovia.

PROCEDURE

This descriptive epidemiologic feasibility study collected dried blood spots from 2,785 consecutive newborns delivered at a hospital in Monrovia. Samples were analyzed by isoelectric focusing at a regional reference laboratory. Infants with SCD were referred for preventive care.

RESULTS

SCT occurred in 10.31% of infants screened. SCD occurred in 33 infants screened [1.19% (95% confidence interval [CI]: 0.79-1.59%)] (FS: 28/33, FSB: 2/33, FSA: 2/33, FSX: 1/33). There were no infants with FSC phenotype observed. Nonsickling hemoglobin phenotypes "FC" and "F" were each present in three infants screened. Seventy-six percent of infants with SCD were brought to care, demonstrating the feasibility of our approach.

CONCLUSIONS

The incidence of SCD and other hemoglobinopathies remains high in Liberia. Additional studies are needed to clarify sickle genotypes and identify the contribution of silent beta-thalassemia alleles. By developing regional partnerships, countries similar to Liberia can acquire current data to inform NBS as an important public health initiative toward improving child health.

A Prospective Cohort Quality Improvement Study to Reduce the Time to Antibiotics for New Fever in Neutropenic Pediatric Oncology Inpatients

BACKGROUND

Fever and neutropenia (F&N) is a pediatric oncology emergency due to the risk of disseminated infection. Quality improvement (QI) efforts to improve time to antibiotics for F&N in the emergency department have been documented, but the issue has not been studied in the established inpatient setting.

PROCEDURE

We undertook a prospective cohort QI study to decrease time to antibiotics for neutropenic pediatric oncology inpatients with new fever to <60 min. Our key intervention was discussion of a plan in case of new fever, including antibiotic(s) to be started, for each patient on rounds. Timing for each step in the process, from fever identification to antibiotic administration, was measured through the electronic medical record for each fever event.

RESULTS

The median time to antibiotics during the 3-three month intervention study period was 76.0 min, although the distribution was skewed due to several long outliers (mean 142.5, interquartile range 51-206, range 47-593 min). Time to antibiotics was significantly shorter when a fever contingency plan was documented in the most recent note than not (mean 102 vs. 254 min, P = 0.039). Over the total 2.75 year data-collection period, the quarterly percentage of patients receiving antibiotics within 60 min has improved from 35 to 65, whereas quarterly mean time to antibiotics has improved from 99 to 50 min.

CONCLUSIONS

Daily discussion of a fever contingency plan appears effective in decreasing the time to antibiotics for neutropenic pediatric oncology inpatients with new fever, likely by circumventing the need for multi-level discussion of the antibiotic plan when fever is identified.

A Successful US Academic Collaborative Supporting Medical Education in a Postconflict Setting

This article describes a model employed by the Academic Collaborative to Support Medical Education in Liberia to augment medical education in a postconflict setting where the health and educational structures and funding are very limited. We effectively utilized a cohort of visiting US pediatric faculty and trainees for short-term but recurrent clinical work and teaching. This model allows US academic medical centers, especially those with smaller residency programs, to provide global health experiences for faculty and trainees while contributing to the strengthening of medical education in the host country. Those involved can work toward a goal of sustainable training with a strengthened host country specialty education system. Partnerships such as ours evolve over time and succeed by meeting the needs of the host country, even during unanticipated challenges, such as the Ebola virus outbreak in West Africa.

Sickle cell disease caused by Hb S/Québec-CHORI: treatment with hydroxyurea and response

Sickle hemoglobin (Hb S;betaGlu 6 Val) is due to an A>T transversion in codon 6 of the beta-globin gene. Other variant hemoglobins mimic Hb A, S, or C on newborn screening and clinical laboratory diagnostic tools, thus making their correct identification potentially difficult. Sickling disorders can result in individuals who are compound heterozygous for beta-globin mutations (e.g., Hb SC, HbSO(Arab)). The authors report a second case of HbS/Québec-CHORI, a severe compound heterozygous sickling disorder and their experience managing this patient with hydroxyurea.

Acquired immune cytopenias post-cardiac transplantation respond to rituximab

Hematologic abnormalities following solid organ transplantation are infrequently autoimmune in origin. We present a series of autoimmune cytopenias developing as a late complication of pediatric cardiac transplantation. Autoimmune cytopenias represented include autoimmune hemolytic anemia, acquired Glanzmann thrombasthenia, and idiopathic thrombocytopenic purpura. Standard therapies were used in each patient without sustainable results. Eventually, each patient was treated with and responded to rituximab. In this report, we review these cases, propose potential mechanisms for development of autoimmune cytopenias, and discuss our experience with rituximab in managing refractory autoimmune cytopenias.

X-linked gray platelet syndrome due to a GATA1 Arg216Gln mutation

We identified a family with gray platelet syndrome (GPS) segregating as a sex-linked trait. Affected males had a mild bleeding disorder, thrombocytopenia, and large agranular platelets characteristic of GPS, while obligate carrier females were asymptomatic but had dimorphic platelets on peripheral smear. Associated findings included mild erythrocyte abnormalities in affected males. Linkage analysis revealed a 63 cM region on the X chromosome between markers G10578 and DXS6797, which segregated with the platelet phenotype and included the GATA1 gene. Sequencing of GATA1 revealed a G-to-A mutation at position 759 corresponding to amino acid change Arg216Gln. This mutation was previously described as a cause of X-linked thrombocytopenia with thalassemia (XLTT) but not of gray platelet syndrome. Our findings suggest that XLTT is within a spectrum of disorders constituting the gray platelet syndrome, and we propose that GATA1 is an upstream regulator of the genes required for platelet alpha-granule biogenesis.