Oral Iptacopan Monotherapy in Paroxysmal Nocturnal Hemoglobinuria.

BACKGROUND: Persistent hemolytic anemia and a lack of oral treatments are challenges for patients with paroxysmal nocturnal hemoglobinuria who have received anti-C5 therapy or have not received complement inhibitors. Iptacopan, a first-in-class oral factor B inhibitor, has been shown to improve hemoglobin levels in these patients. METHODS: In two phase 3 trials, we assessed iptacopan monotherapy over a 24-week period in patients with hemoglobin levels of less than 10 g per deciliter. In the first, anti-C5-treated patients were randomly assigned to switch to iptacopan or to continue anti-C5 therapy. In the second, single-group trial, patients who had not received complement inhibitors and who had lactate dehydrogenase (LDH) levels more than 1.5 times the upper limit of the normal range received iptacopan. The two primary end points in the first trial were an increase in the hemoglobin level of at least 2 g per deciliter from baseline and a hemoglobin level of at least 12 g per deciliter, each without red-cell transfusion; the primary end point for the second trial was an increase in hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion. RESULTS: In the first trial, 51 of the 60 patients who received iptacopan had an increase in the hemoglobin level of at least 2 g per deciliter from baseline, and 42 had a hemoglobin level of at least 12 g per deciliter, each without transfusion; none of the 35 anti-C5-treated patients attained the end-point levels. In the second trial, 31 of 33 patients had an increase in the hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion. In the first trial, 59 of the 62 patients who received iptacopan and 14 of the 35 anti-C5-treated patients did not require or receive transfusion; in the second trial, no patients required or received transfusion. Treatment with iptacopan increased hemoglobin levels, reduced fatigue, reduced reticulocyte and bilirubin levels, and resulted in mean LDH levels that were less than 1.5 times the upper limit of the normal range. Headache was the most frequent adverse event with iptacopan. CONCLUSIONS: Iptacopan treatment improved hematologic and clinical outcomes in anti-C5-treated patients with persistent anemia - in whom iptacopan showed superiority to anti-C5 therapy - and in patients who had not received complement inhibitors. (Funded by Novartis; APPLY-PNH ClinicalTrials.gov number, NCT04558918; APPOINT-PNH ClinicalTrials.gov number, NCT04820530.).

Survival of transfused red blood cells from a donor with alpha-thalassemia trait in a recipient with sickle cell disease.

BACKGROUND: Post-transfusion survival of donor red blood cells (RBCs) is important for effective chronic transfusion therapy in conditions including sickle cell disease (SCD). Biotin labeling RBCs allows direct in vivo measurement of multiple donor RBC units simultaneously post-transfusion. STUDY DESIGN AND METHODS: In an observational trial of patients with SCD receiving monthly chronic transfusion therapy, aliquots of RBCs from one transfusion episode were biotin-labeled and infused along with the unlabeled RBC units. Serial blood samples were obtained to measure RBC survival. Donor units were tested for RBC indices, hemoglobin fractionation, and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. For microcytic donor RBCs (MCV < 70 fL), HBA1 and HBA2 genetic testing was performed on whole blood. RESULTS: We present one recipient, a pediatric patient with SCD and splenectomy who received two RBC units with aliquots from each unit labeled at distinct biotin densities (2 and 18 µg/mL biotin). One donor unit was identified to have microcytosis (MCV 68.5 fL after biotinylation); whole blood sample obtained at a subsequent donation showed 2-gene deletion alpha-thalassemia trait (ɑ-3.7kb/ɑ-3.7kb) and normal serum ferritin. G6PD activity was >60% of normal mean for both. The RBCs with alpha-thalassemia RBC had accelerated clearance and increased surface phosphatidylserine post-transfusion, as compared with the normocytic RBC (half life 65 vs. 86 days, respectively). DISCUSSION: Post-transfusion RBC survival may be lower for units from donors with alpha-thalassemia trait, although the impact of thalassemia trait donors on transfusion efficacy requires further study.

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.

Mortality in adults with sickle cell disease: Results from the sickle cell disease implementation consortium (SCDIC) registry.

The cause of death in people affected by sickle cell disease (SCD) is often challenging to define as prior studies have used retrospective or administrative data for analysis. We used a prospective longitudinal registry to assess mortality and clinical co-morbidities among subjects enrolled in the Sickle Cell Disease Implementation Consortium (SCDIC) registry. At enrollment, we collected the following data: patient-reported demographics, SCD phenotype, baseline laboratory values, comorbidities, and current medications. Subjects were followed for a median of 4.7 years before the present analysis. The relationship of clinical co-morbidities (at time of enrollment) to mortality was determined using survival analysis, adjusting for SCD phenotype and gender. There was a total of 2439 people with SCD enrolled in the SCDIC registry. One hundred and twenty-eight participants (5%) died during the observation period (2017-2022). Six people died from trauma and were excluded from further analysis. Proximate cause of death was unwitnessed in 17% of the deaths, but commonest causes of death include cardiac (18%), acute chest or respiratory failure (11%), sudden unexplained death (8%). Enrollment characteristics of the individuals who died (n = 122) were compared to those of survivors (n = 2317). Several co-morbidities at enrollment increased the odds of death on univariate analysis. All co-morbidities were included in a multivariable model. After backward elimination, iron overload, pulmonary hypertension, and depression, remained statistically significant predictors of the risk of death. SCD reduces life expectancy. Improved comprehensive and supportive care to prevent end-organ damage and address comorbidities is needed for this population.

Pregnancy outcomes with hydroxyurea use in women with sickle cell disease.

Hydroxyurea reduces pain crises, acute chest syndrome, and blood transfusions in sickle cell disease (SCD), but potential detrimental effects on fertility and birth outcomes impede its use. Data on the effects of hydroxyurea taken for SCD during conception and pregnancy are scarce. The Sickle Cell Disease Implementation Consortium collected self-reported pregnancy history, corresponding hydroxyurea use, and pregnancy outcomes in women with SCD in the clinical setting. Among 1285 women 18-45 years of age, 737 (57.4%) reported 1788 pregnancies (1079 live births, 394 miscarriages, 40 stillbirths, 207 abortions, 48 current pregnancies, and 20 missing outcomes) of which 241 (15.9%) live births, miscarriages or stillbirths were conceived while on hydroxyurea. In univariate analyses, pregnancy number more than three, severe sickle genotype, history of stillbirth or miscarriage, and chronic kidney disease at enrollment were covariates significantly associated with a pregnancy ending in miscarriage or stillbirth. After adjustment for covariates and additional SCD severity markers in multivariate analyses, hydroxyurea use during conception and pregnancy, but not during conception only, was associated with an increase in the odds ratio (OR) of miscarriage or stillbirth (OR 2.21, 95% confidence interval [CI] 1.40-3.47). In analyses of live birth outcomes, hydroxyurea use during conception and pregnancy was associated with birth weight < 5.5 pounds in full-term infants (OR 2.98, 95% CI 1.09-7.38) but not with prematurity or serious medical problems at birth. These findings suggest that hydroxyurea use may be safe up to the time of conception, but that clinicians should continue to advise caution regarding use during pregnancy.

Indolent T-Lymphoblastic Proliferation in Idiopathic Multicentric Castleman Disease.

Benign and polyclonal proliferation of immature T cells in a lymph node with preserved morphological architecture is called indolent T-lymphoblastic proliferation (iT-LBP). Although overall rare, they have been described in association with both benign and malignant disorders including Castleman disease. We report the first case of idiopathic multicentric Castleman disease associated with iT-LBP, all previous reports of iT-LBP in Castleman disease were unicentric. A 37-year-old-male presented with 3 months of fevers and B-symptoms and was found to have enlargement of multiple bilateral lymph node sites on both sides of diaphragm along with splenomegaly. Anemia, elevated C-reactive protein, hypoalbuminemia, and elevated interleukin-6 levels were present. Biopsy of a lymph node showed features suggestive of idiopathic multicentric Castleman disease and iT-LBP. Bone marrow biopsy was unremarkable. Siltuximab and steroids were used to treat the condition.

Sickle cell disease: progress towards combination drug therapy.

Dr. John Herrick described the first clinical case of sickle cell anaemia (SCA) in the United States in 1910. Subsequently, four decades later, Ingram and colleagues characterized the A to T substitution in DNA producing the GAG to GTG codon and replacement of glutamic acid with valine in the sixth position of the ßS -globin chain. The establishment of Comprehensive Sickle Cell Centers in the United States in the 1970s was an important milestone in the development of treatment strategies and describing the natural history of sickle cell disease (SCD) comprised of genotypes including homozygous haemoglobin SS (HbSS), HbSß0 thalassaemia, HbSC and HbSß+ thalassaemia, among others. Early drug studies demonstrating effective treatments of HbSS and HbSß0 thalassaemia, stimulated clinical trials to develop disease-specific therapies to induce fetal haemoglobin due to its ability to block HbS polymerization. Subsequently, hydroxycarbamide proved efficacious in adults with SCA and was Food and Drug Administration (FDA)-approved in 1998. After two decades of hydroxycarbamide use for SCD, there continues to be limited clinical acceptance of this chemotherapy drug, providing the impetus for investigators and pharmaceutical companies to develop non-chemotherapy agents. Investigative efforts to determine the role of events downstream of deoxy-HbS polymerization, such as endothelial cell activation, cellular adhesion, chronic inflammation, intravascular haemolysis and nitric oxide scavenging, have expanded drug targets which reverse the pathophysiology of SCD. After two decades of slow progress in the field, since 2018 three new drugs were FDA-approved for SCA, but research efforts to develop treatments continue. Currently over 30 treatment intervention trials are in progress to investigate a wide range of agents acting by complementary mechanisms, providing the rationale for ushering in the age of effective and safe combination drug therapy for SCD. Parallel efforts to develop curative therapies using haematopoietic stem cell transplant and gene therapy provide individuals with SCD multiple treatment options. We will discuss progress made towards drug development and potential combination drug therapy for SCD with the standard of care hydroxycarbamide.

DIAPH1 Mutation as a Novel Cause of Autosomal Dominant Macrothrombocytopenia and Hearing Loss.

Macrothrombocytopenia (MTP) is a group of rare disorders characterized by giant platelets, thrombocytopenia, and variable association with abnormal bleeding. Inherited MTP are frequently misdiagnosed as immune thrombocytopenia. Associated second-organ manifestation can help narrow down syndromic MTPs. We describe a case of autosomal dominant sensorineural hearing loss and MTP caused by a gain of function mutation in DIAPH1. This mutation causes altered megarkaryopoiesis and platelet cytoskeletal deregulation. Although hearing loss and MTP were likely progressive, clinically significant bleeding was not observed. DIAPH1-related MTP can be distinguished clinically from MYH9 mutation by the absence of cataracts and glomerular disease.

Regulation of iron homeostasis through the erythroferrone-hepcidin axis in sickle cell disease.

Sickle cell disease (SCD) has a distinct pattern of transfusional iron overload (IO) when compared to transfusion-dependent ß-thalassaemia major (TDT). We conducted a single institution prospective study to evaluate plasma biomarkers of iron regulation and inflammation in patients with SCD with IO (SCD IO cases, n = 22) and without IO (SCD non-IO cases, n = 11), and non-SCD controls (n = 13). Hepcidin was found to be inappropriately low, as evidenced by a significantly higher median hepcidin/ferritin ratio in non-SCD controls compared to SCD IO cases (0·3 vs. 0·02, P < 0·0001) and SCD non-IO cases (0·3 vs. 0·02, P < 0·0001), suggesting that certain inhibitory mechanism (s) work to suppress hepcidin in SCD. As opposed to the SCD non-IO state, where hepcidin shows a strong significant positive correlation with ferritin (Spearman ρ = 0·7, P = 0·02), this correlation was lost when IO occurs (Spearman ρ = -0·2, P = 0·4). Although a direct non-linear correlation between erythroferrone (ERFE) and hepcidin did not reach statistical significance both in the IO (Spearman ρ = -0·4, P = 0·08) and non-IO state (Spearman ρ = -0·6, P = 0·07), patients with highest ERFE had low hepcidin levels, suggesting that ERFE contributes to hepcidin regulation in some patients. Our results suggest a multifactorial mechanism of hepcidin regulation in SCD.

Crizanlizumab for the Prevention of Pain Crises in Sickle Cell Disease.

BACKGROUND: The up-regulation of P-selectin in endothelial cells and platelets contributes to the cell-cell interactions that are involved in the pathogenesis of vaso-occlusion and sickle cell-related pain crises. The safety and efficacy of crizanlizumab, an antibody against the adhesion molecule P-selectin, were evaluated in patients with sickle cell disease. METHODS: In this double-blind, randomized, placebo-controlled, phase 2 trial, we assigned patients to receive low-dose crizanlizumab (2.5 mg per kilogram of body weight), high-dose crizanlizumab (5.0 mg per kilogram), or placebo, administered intravenously 14 times over a period of 52 weeks. Patients who were receiving concomitant hydroxyurea as well as those not receiving hydroxyurea were included in the study. The primary end point was the annual rate of sickle cell-related pain crises with high-dose crizanlizumab versus placebo. The annual rate of days hospitalized, the times to first and second crises, annual rates of uncomplicated crises (defined as crises other than the acute chest syndrome, hepatic sequestration, splenic sequestration, or priapism) and the acute chest syndrome, and patient-reported outcomes were also assessed. RESULTS: A total of 198 patients underwent randomization at 60 sites. The median rate of crises per year was 1.63 with high-dose crizanlizumab versus 2.98 with placebo (indicating a 45.3% lower rate with high-dose crizanlizumab, P=0.01). The median time to the first crisis was significantly longer with high-dose crizanlizumab than with placebo (4.07 vs. 1.38 months, P=0.001), as was the median time to the second crisis (10.32 vs. 5.09 months, P=0.02). The median rate of uncomplicated crises per year was 1.08 with high-dose crizanlizumab, as compared with 2.91 with placebo (indicating a 62.9% lower rate with high-dose crizanlizumab, P=0.02). Adverse events that occurred in 10% or more of the patients in either active-treatment group and at a frequency that was at least twice as high as that in the placebo group were arthralgia, diarrhea, pruritus, vomiting, and chest pain. CONCLUSIONS: In patients with sickle cell disease, crizanlizumab therapy resulted in a significantly lower rate of sickle cell-related pain crises than placebo and was associated with a low incidence of adverse events. (Funded by Selexys Pharmaceuticals and others; SUSTAIN ClinicalTrials.gov number, NCT01895361 .).

Characteristics and potential biomarkers of adult sickle cell patients with chronic pain.

OBJECTIVES: In this study, we investigated the evolution of chronic pain in sickle cell patients (SCD) as an age-dependent phenomenon and studied the frequency of vaso-occlusive episode frequency, opioid use, quantitative sensory testing (QST), and biomarkers of chronic pain (CP). METHODS: We undertook a cross-sectional study of the evolution of CP in SCD. A total of 72 subjects (age 15-66) were enrolled. VOE frequency, presence of CP hydroxyurea (HU) therapy, opioid use, and laboratory parameters were collected. QST was performed, and plasma tryptase, substance P, and NGF (Nerve Growth Factor) levels were assayed. RESULTS: There was an age-dependent increase in frequency of CP, VOEs, opioid use, and Von Frey monofilament values. CP patients had significantly higher opioid use (daily morphine equivalents) (52.8 mg vs 6.94 mg, P = .009), suggesting a correlation between opioid use and hyperalgesia. NGF levels were also significantly higher (P = .051). Our results confirm previous observations of an age-dependent increase in the proportion of patients with CP and support the contributing role of mast cell activation and neurogenic inflammation. CONCLUSIONS: This is the first study of NGF as a possible biomarker of CP in SCD. If confirmed, this could provide a diagnostic marker and therapeutic target for CP in SCD.

Outcomes of an Emergency Department Observation Unit-Based Pathway for the Treatment of Uncomplicated Vaso-occlusive Events in Sickle Cell Disease.

STUDY OBJECTIVE: This was a prospective, pre-post, 13-year observational study documenting the multiyear implementation of an observation unit sickle cell pathway for patients with uncomplicated vaso-occlusive events. METHODS: The sickle cell pathway begins with rapid triage to identify patients with uncomplicated vaso-occlusive events for immediate transfer to the observation unit and initiation of patient-controlled analgesia followed by repeated evaluations of pain and identification of other complications. Data were abstracted from the electronic medical record or observation unit database. The sickle cell pathway was initiated in April 2006. Major revisions of it were carried out in June 2009 (physician evaluation occurs in sickle cell pathway and only patient-controlled analgesia administration of medications) and October 2010 (multidisciplinary management and individual dosing). RESULTS: Annual ED visits ranged between 287 and 528. The preimplementation hospital admission rate was 33% (123/368), 3-day return rate 16% (60/368), and 30-day return rate 67% (248/368). Refinements to the sickle cell pathway have resulted in a decrease in admission rate to 20% (258/1276); 3-day return rate, to 3.6% (46/1,276); and 30-day return rate, to 41% (525/1,276) for the past 3 years. CONCLUSION: The use of a sickle cell pathway for the treatment of uncomplicated vaso-occlusive events has been effective in providing rapid treatment and reducing hospital admissions. However, it was not only the intervention and its refinement that made the sickle cell pathway successful. With the Consolidated Framework for Implementation Research, it was discerned that outer setting factors of organizational commitment to the care of patients with SCD, inner setting factors of learning climate and leadership engagement, individuals, and process contributed to the success of the sickle cell pathway.

Effect of crizanlizumab on pain crises in subgroups of patients with sickle cell disease: A SUSTAIN study analysis.

The cell adhesion molecule P-selectin plays a key role in the pathogenesis of a vaso-occlusive crisis (VOC) in patients with sickle cell disease (SCD). In the double-blind, placebo-controlled phase 2 SUSTAIN study, crizanlizumab (humanized, anti-P-selectin monoclonal antibody) 5 mg/kg significantly lowered the rate of VOC in patients with SCD by 45% vs placebo. In SUSTAIN, patients with SCD were randomized to crizanlizumab 2.5 mg/kg, crizanlizumab 5 mg/kg, or placebo intravenously 14 times over 52 weeks. The primary endpoint was the annual rate of VOC with crizanlizumab vs placebo. This post hoc descriptive analysis evaluated the proportion of patients who did not experience a VOC during the study in the following subgroups: VOCs in the year prior to study entry (2-4/5-10), SCD genotype (HbSS/non-HbSS), and concomitant hydroxyurea use (yes/no). More patients were VOC event-free in the crizanlizumab 5 mg/kg arm than in the placebo arm, including those with more frequent prior VOCs (ie, 5-10; 28.0% vs 4.2%), the HbSS genotype (31.9% vs 17.0%) and/or using concomitant hydroxyurea (33.3% vs 17.5%). Further analyses of secondary endpoints demonstrated that crizanlizumab treatment significantly increased time-to-first VOC vs placebo in these subgroups. The rates of treatment-emergent adverse events were similar between treatment arms across all subgroups. This post hoc analysis of SUSTAIN shows that in patients with a high number of prior VOCs, on concomitant hydroxyurea and/or with the HbSS genotype, crizanlizumab treatment increases the likelihood of patients being VOC event-free and delays time-to-first VOC.

Long-Term Endothelin-A Receptor Antagonism Provides Robust Renal Protection in Humanized Sickle Cell Disease Mice.

Sickle cell disease (SCD)-associated nephropathy is a major source of morbidity and mortality in patients because of the lack of efficacious treatments targeting renal manifestations of the disease. Here, we describe a long-term treatment strategy with the selective endothelin-A receptor (ETA) antagonist, ambrisentan, designed to interfere with the development of nephropathy in a humanized mouse model of SCD. Ambrisentan preserved GFR at the level of nondisease controls and prevented the development of proteinuria, albuminuria, and nephrinuria. Microscopy studies demonstrated prevention of podocyte loss and structural alterations, the absence of vascular congestion, and attenuation of glomerulosclerosis in treated mice. Studies in isolated glomeruli showed that treatment reduced inflammation and oxidative stress. At the level of renal tubules, ambrisentan treatment prevented the increased excretion of urinary tubular injury biomarkers. Additionally, the treatment strategy prevented tubular brush border loss, diminished tubular iron deposition, blocked the development of interstitial fibrosis, and prevented immune cell infiltration. Furthermore, the prevention of albuminuria in treated mice was associated with preservation of cortical megalin expression. In a separate series of identical experiments, combined ETA and ETB receptor antagonism provided only some of the protection observed with ambrisentan, highlighting the importance of exclusively targeting the ETA receptor in SCD. Our results demonstrate that ambrisentan treatment provides robust protection from diverse renal pathologies in SCD mice, and suggest that long-term ETA receptor antagonism may provide a strategy for the prevention of renal complications of SCD.

Hydroxycarbamide versus chronic transfusion for maintenance of transcranial doppler flow velocities in children with sickle cell anaemia-TCD With Transfusions Changing to Hydroxyurea (TWiTCH): a multicentre, open-label, phase 3, non-inferiority trial.

BACKGROUND: For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions. METHODS: TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD flow velocities (≥ 200 cm/s) but no severe vasculopathy. After screening, eligible participants were randomly assigned 1:1 to continue standard transfusions (standard group) or hydroxycarbamide (alternative group). Randomisation was done at a central site, stratified by site with a block size of four, and an adaptive randomisation scheme was used to balance the covariates of baseline age and TCD velocity. The study was open-label, but TCD examinations were read centrally by observers masked to treatment assignment and previous TCD results. Participants assigned to standard treatment continued to receive monthly transfusions to maintain 30% sickle haemoglobin or lower, while those assigned to the alternative treatment started oral hydroxycarbamide at 20 mg/kg per day, which was escalated to each participant's maximum tolerated dose. The treatment period lasted 24 months from randomisation. The primary study endpoint was the 24 month TCD velocity calculated from a general linear mixed model, with the non-inferiority margin set at 15 cm/s. The primary analysis was done in the intention-to-treat population and safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, number NCT01425307. FINDINGS: Between Sept 20, 2011, and April 17, 2013, 159 patients consented and enrolled in TWiTCH. 121 participants passed screening and were then randomly assigned to treatment (61 to transfusions and 60 to hydroxycarbamide). At the first scheduled interim analysis, non-inferiority was shown and the sponsor terminated the study. Final model-based TCD velocities were 143 cm/s (95% CI 140-146) in children who received standard transfusions and 138 cm/s (135-142) in those who received hydroxycarbamide, with a difference of 4·54 (0·10-8·98). Non-inferiority (p=8·82 × 10(-16)) and post-hoc superiority (p=0·023) were met. Of 29 new neurological events adjudicated centrally by masked reviewers, no strokes were identified, but three transient ischaemic attacks occurred in each group. Magnetic resonance brain imaging and angiography (MRI and MRA) at exit showed no new cerebral infarcts in either treatment group, but worsened vasculopathy in one participant who received standard transfusions. 23 severe adverse events in nine (15%) patients were reported for hydroxycarbamide and ten serious adverse events in six (10%) patients were reported for standard transfusions. The most common serious adverse event in both groups was vaso-occlusive pain (11 events in five [8%] patients with hydroxycarbamide and three events in one [2%] patient for transfusions). INTERPRETATION: For high-risk children with sickle cell anaemia and abnormal TCD velocities who have received at least 1 year of transfusions, and have no MRA-defined severe vasculopathy, hydroxycarbamide treatment can substitute for chronic transfusions to maintain TCD velocities and help to prevent primary stroke. FUNDING: National Heart, Lung, and Blood Institute, National Institutes of Health.

Hydroxyurea differentially modulates activator and repressors of γ-globin gene in erythroblasts of responsive and non-responsive patients with sickle cell disease in correlation with Index of Hydroxyurea Responsiveness.

Hydroxyurea (HU), the first of two drugs approved by the US Food and Drug Administration for treating patients with sickle cell disease (SCD), produces anti-sickling effect by re-activating fetal γ-globin gene to enhance production of fetal hemoglobin. However, approximately 30% of the patients do not respond to HU therapy. The molecular basis of non-responsiveness to HU is not clearly understood. To address this question, we examined HU-induced changes in the RNA and protein levels of transcription factors NF-Y, GATA-1, -2, BCL11A, TR4, MYB and NF-E4 that assemble the γ-globin promoter complex and regulate transcription of γ-globin gene. In erythroblasts cultured from peripheral blood CD34+ cells of patients with SCD, we found that HU-induced changes in the protein but not the RNA levels of activator GATA-2 and repressors GATA-1, BCL11A and TR4 correlated with HU-induced changes in fetal hemoglobin (HbF) levels in the peripheral blood of HU high and low responders. However, HU did not significantly induce changes in the protein or RNA levels of activators NF-Y and NF-E4. Based on HU-induced changes in the protein levels of GATA-2, -1 and BCL11A, we calculated an Index of Hydroxyurea Responsiveness (IndexHU-3). Compared to the HU-induced fold changes in the individual transcription factor protein levels, the numerical values of IndexHU-3 statistically correlated best with the HU-induced peripheral blood HbF levels of the patients. Thus, IndexHU-3 can serve as an appropriate indicator for inherent HU responsiveness of patients with SCD.

Pulmonary platelet thrombi and vascular pathology in acute chest syndrome in patients with sickle cell disease.

A growing body of evidence suggests a role for platelets in sickle cell disease (SCD). Despite the proinflammatory, occlusive nature of platelets, a role for platelets in acute chest syndrome (ACS), however, remains understudied. To provide evidence and potentially describe contributory factors for a putative link between ACS and platelets, we performed an autopsy study of 20 SCD cases-10 of whom died from ACS and 10 whose deaths were not ACS-related. Pulmonary histopathology and case history were collected. We discovered that disseminated pulmonary platelet thrombi were present in 3 out of 10 of cases with ACS, but none of the matched cases without ACS. Those cases with detected thrombi were associated with significant deposition of endothelial vWF and detection of large vWF aggregates adhered to endothelium. Potential clinical risk factors were younger age and higher platelet count at presentation. However, we also noted a sharp and significant decline in platelet count prior to death in each case with platelet thrombi in the lungs. In this study, neither hydroxyurea use nor perimortem transfusion was associated with platelet thrombi. Surprisingly, in all cases, there was profound pulmonary artery remodeling with both thrombotic and proliferative pulmonary plexiform lesions. The severity of remodeling was not associated with a severe history of ACS, or hydroxyurea use, but was inversely correlated with age. We thus provide evidence of undocumented presence of platelet thrombi in cases of fatal ACS and describe clinical correlates. We also provide novel correlates of pulmonary remodeling in SCD.