Identification of Biomarkers That Are Associated with Clinical Complications of Hemoglobin SC Disease and Sickle Cell Anemia

Abstract Introduction: Sickle cell disease (SCD) is an umbrella term used to describe inherited anemias that originate from a mutation in HBB, the gene coding for β-globin, that causes the formation of the abnormal hemoglobin S (HbS). The two most common genotypes are HbSS, termed sickle cell anemia (SCA) and HbSC, termed hemoglobin SC disease. Due to the higher prevalence and more severe clinical symptoms in SCA, attention is focused on this latter group of patients. Patients with HbSC disease who report significant SCD related symptoms are treated largely the same as SCA patients, despite differences in disease pathophysiology. Objective: To evaluate rheological differences in red blood cells (RBC) and whole blood from individuals with SCA and HbSC, and examine for associations with clinical complications. Methods: We analyzed an adult (n=30) and pediatric cohort (n=226) of SCA and HbSC individuals. Blood samples were evaluated for percent dense red blood cells (% DRBC), whole blood viscosity, and several ektacytometry-derived parameters, such as the cell membrane stability test, osmotic gradient ektacytometry and Point of Sickling (PoS): an oxygen gradient ektacytometry-derived biomarker that depicts the oxygen tension at which sickling is initiated. Subsequently, we assessed in the pediatric cohort (189 SCA and 37 HbSC individuals) if PoS, dense RBCs or blood viscosity are associated with clinical complications. Results: In particular (micro)dense RBCs (Figure 1A and B), blood viscosity (Figure 1C) and point of sickling (PoS, Figure 1D-F), are notably different in HbSC disease compared to SCA. In SCA, PoS was associated with occurrence of acute chest syndrome (ACS, for every 10mmHg increase OR 1.84, p<0.0001, adjusted OR 1.67, p=0.002), but no such association was found in children with HbSC. In contrast, we found an association of blood viscosity and ACS (OR 9.3, p=0.012; adjusted OR 13.5, p=0.015) in HbSC children, while we found no such association in SCA. No significant association of micro dense RBCs was found in SCA or HbSC children. Conclusion: We found that associations between PoS and ACS found in SCA were not found in HbSC. Instead, in HbSC ACS was associated with higher whole blood viscosity. We therefore conclude that sickling is a key factor in the pathophysiology of SCA, whereas in HbSC disease blood viscosity might play a crucial role in development of certain complications like ACS. This study suggests that complications in SCA and HbSC disease are driven by different aspects of blood abnormalities, and may warrant a distinct treatment approach. Figure 1 Figure 1. Disclosures Rab: Axcella Health: Research Funding; Agios Pharmaceuticals: Research Funding. Schutgens: Shire/Takeda: Research Funding; Pfizer: Research Funding; OctaPharma: Research Funding; Novo Nordisk: Research Funding; CSL Behring: Research Funding; Bayer: Research Funding. Wijk: Axcella health: Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding. Van Beers: Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; RR Mechatronics: Research Funding; Pfizer: Research Funding. Sheehan: Beam Therapeutics: Research Funding; Novartis: Research Funding; Forma Therapeutics: Research Funding.

Download Full-text

Sickle-Cell Disease in Greece: Patient Reported Outcomes Related to Clinical Complications, Treatment Choices and Attitudes, Beliefs and Trends Affecting Potential Participation in Clinical Trials - a Greek National Multicentric Study

Blood ◽

10.1182/blood-2019-127966 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4838-4838

Author(s):

Sophia Delicou ◽

Michael D. Diamantidis ◽

Konstantinos Manganas ◽

Eftychios Eftychiadis ◽

Despoina Pantelidou ◽

...

Keyword(s):

Clinical Trial ◽

Clinical Trials ◽

Board Of Directors ◽

Sickle Cell ◽

Research Funding ◽

Educational Status ◽

Current Treatment ◽

Advisory Committees ◽

Chi Square ◽

Clinical Complications

Background: Sickle cell disease (SCD) is an autosomal recessive disorder caused by a point mutation in the β-globin chain of hemoglobin that forms hemoglobin S. It is clinically characterized by complicated episodes of veno-occlusive crises (VOC), emergency room (ER) visits and uncomplicated inpatient admissions. Aim: We investigated the clinical complications and treatment choices of a large cohort of Greek SCD patients, representative of the whole country. Most importantly, this study aimed to assess patients' attitudes and beliefs regarding their enrollment in clinical trials testing new drugs. We examined the factors influencing such a participation. Patients and Methods: A total of 254 patients from 10 Thalassemia and Sickle Cell Departments across Greece (110 men/144 women), aged 18 - over 65, 210 (82.7%) with β-thalassemia/sickle cell trait and 44 (17.3%) with homozygous SCD participated in the study. The participants had variable educational and socioeconomic background. They all answered an anonymous self-report questionnaire during their medical evaluations between November 2018 and May 2019, including their demographic and clinical characteristics, their current treatment and their opinion regarding a possible participation in a clinical trial for SCD. Descriptive statistical analysis using calculated scale variables and Chi-square test were performed. Results: All participants completed the survey. During the previous year, 64 patients (25.3%) had no admissions for VOC, 128 (50.6%) had 1-5, whereas 21 (8.3%) had 5-10 and 40 (15.8%) more than 10. Except for acute pain crises, the most frequent complications were chronic pain (59%), liver/spleen dysfunction (32.4%), infectious episodes (29.5%), iron overload (23.8%) and pulmonary hypertension (20.1%). In addition to hematological care, patients seeked medical attention from expert physicians for disease complications; 77.6% of the patients reported that they yearly visited a cardiologist, 42.4% an ophthalmologist, 31.9% an orthopedic, 28.4% a pneumonologist, 28.9% a hepatologist, 12.6% an urologist, 14% a nephrologist, 11.9% an infectious disease doctor, 10.1% a pain management specialist and 8.1% a neurologist. The therapeutic approaches included daily folic acid supplementation (86.1%), vaccines (68.3%), hydroxyurea (66.3%), antibiotics (57.1%), simple pain moderators (52.4%), opioids (48.8%) and iron chelators (30.2%). Previous experience in clinical trials was reported by only 17 patients (6.9%). Regarding the patients' attitudes towards a probable clinical trial, 41.3% were positive to try new therapies, 28.3% negative and 30.4% neutral. 67.2% were satisfied with their current treatment, without excluding a potential participation in clinical trials; such treatment satisfaction correlated significantly with older age, lower income and secondary hemochromatosis under chelation treatment (p<0.05). 40% reported that they had been waiting for years for a new treatment, but 43.2% strongly denied becoming an experimental mouse model, whereas 47.3% mentioned that they would trust their doctors' advice correlating positively with male gender and higher income (p<0.05). Lower educational status, prior intake of hydroxyurea and residence/origin in the capital in contrast to the countryside (chi-square, p<0.05) significantly correlated with a potential clinical trial participation. Internet and television information motivated patients to seek more details from their doctor. Concerning the factors rated as the most important for a potential participation in a clinical trial, 7 out of 10 patients of our cohort considered of utmost equal importance the effectiveness of a probable treatment and the relative toxicity. Conclusions: Most SCD patients have chronic complications and visit specialized physicians. Since the participation of larger number of patients in clinical trials is essential for the application of novel drugs, the most important factors of our cohort are the effectiveness of a probable treatment and the relative toxicity, along with the trust to the doctor. These factors are crucial, influencing patients' decision. Even though a proportion of our patients remain skeptical towards clinical trials, an increasing number is willing to participate, which correlates positively with residence in the capital, lower educational status and prior intake of hydroxyurea. Disclosures Kattamis: Apopharma: Honoraria; Vertex: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ionis: Membership on an entity's Board of Directors or advisory committees; ViFOR: Membership on an entity's Board of Directors or advisory committees; Novartis Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Symeonidis:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tekeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Download Full-text

Rheological Effects of L-Glutamine in Patients with Sickle Cell Disease

Blood ◽

10.1182/blood-2019-128891 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3567-3567

Author(s):

Celeste K. Kanne ◽

Varun Reddy ◽

Vivien A. Sheehan

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Blood Viscosity ◽

Whole Blood ◽

Blood Cells ◽

Cell Disease ◽

Phase 3 ◽

Whole Blood Viscosity

Background: ENDARITM (oral pharmaceutical L-glutamine powder) received FDA approval in 2017 as a treatment for sickle cell disease (SCD). A pivotal phase 3 clinical study conducted by Emmaus Medical, Inc. showed that L-glutamine resulted in a lower incidence of vaso-occlusive crises (VOC) as well as a lower rate of hospitalizations and shorter hospital stays. No changes in standard clinical laboratory values were noted. The clinical improvements associated with sickle cell complications are believed to be due to an increase in the proportion of the reduced form of nicotinamide adenine dinucleotides in the red blood cells (RBC) of patients with SCD, reducing the oxidative stress. While the endpoints in the phase 3 study are clinically important, it is essential that we identify biomarkers or measurable laboratory changes that can serve as endpoints for future clinical trials assessing dose optimization and the efficacy and safety of L-glutamine in SCD individuals, including those with hepatic and renal dysfunction. RBC rheology is markedly abnormal in SCD; blood is more viscous for a given hematocrit than normal individuals, dense red blood cells (DRBC) are packed with HbS, potentiating sickling, and RBCs are less deformable than those of HbAA or HbAS individuals. High whole blood viscosity, high DRBCs, and poor RBC deformability are associated with higher rates of VOC. Given the demonstrated reduction in pain events, we hypothesized that L-glutamine might improve RBC rheology and sought to test this in vitro and in vivo using a battery of rheological tests. Methods: For the in vitro study, 6 mL of whole blood was drawn into an EDTA vacutainer from ten pediatric patients with sickle cell anemia (HbSS or HbSβ0) during routine clinical checkups under an IRB approved protocol. The cohort included 3 female and 7 male patients, ages 2-19 years old. All patients were on a steady dose of hydroxyurea and did not receive a transfusion within the 3 months prior to sample collection. A 200 mM stock solution of L-glutamine and water was mixed and filtered under light-protected conditions. Aliquots were stored at -20°C to avoid multiple freeze/thaw cycles. L-glutamine was added to 3 mL of whole blood for a final concentration of 1 mM (average in vivo L-glutamine plasma concentration in patients with SCD treated with L-glutamine); 3 mL of the same patient sample with water added served as a control. After a 24-hour incubation period at 4°C, whole blood viscosity was measured using a cone and plate viscometer at 37°C (DV3T Rheometer, AMETEK Brookfield, USA), %DRBCs were measured on an ADVIA 120 Hematology System (Siemens Healthcare Diagnostics, Inc., USA), and deformability measured using a Laser Optical Rotational Red Cell Analyzer (Lorrca®) (RR Mechatronics, the Netherlands) with the Oxygenscan module. The Oxygenscan measures RBC deformability at normoxia (Elmax), deformability upon deoxygenation (EImin), and point of sickling (PoS), the oxygen tension at which deformability begins to decline, reflecting the patient-specific pO2 at which sickling begins. Paired samples (with and without added L-glutamine) were analyzed using Student's t-test. For the in vivo study, rheological tests were performed on peripheral blood from one patient (18-year-old male on hydroxyurea) at baseline and treated with L-glutamine as part of his routine clinical care. Results and conclusions: Addition of L-glutamine in vitro significantly reduced the PoS, meaning RBCs incubated with L-glutamine could tolerate a lower pO2 before sickling compared to the control. RBCs incubated with L-glutamine also had significantly higher EImin, meaning deoxygenated RBCs were more flexible and deformable. Whole blood viscosity at 45s-1 and 225s-1 did not change significantly following incubation with L-glutamine; %DRBCs also did not change significantly (Table 1). The in vivo patient sample tested exhibited a similar improvement in PoS and EImin (Figure 1). We therefore propose to further test the performance of the PoS and EImin as possible biomarkers of response to L-glutamine in vivo. If validated, these biomarkers may also help further elucidate the mechanisms of action of L-glutamine in SCD. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Clonal Tracking By Whole Genome Sequencing Permits Comprehensive Mapping of the Genomic Landscape in Pre- and Post-Gene Therapy Sickle Cell Patients

Blood ◽

10.1182/blood-2021-152262 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 559-559

Author(s):

Alyssa H. Cull ◽

Michael Spencer Chapman ◽

Marioara Ciuculescu ◽

Emily Mitchell ◽

Myriam Armant ◽

...

Keyword(s):

Gene Therapy ◽

Stem Cell ◽

Board Of Directors ◽

Sickle Cell ◽

Research Funding ◽

Phylogenetic Trees ◽

Insertion Site ◽

Advisory Board ◽

Advisory Committees ◽

Genomic Landscape

Abstract Recent advances in clonal stem cell tracking strategies have enabled interrogation of unperturbed human hematopoiesis. Whole genome sequencing (WGS) can be used to map the clonal dynamics of hematopoietic stem and progenitor cells (HSPCs) by employing spontaneous somatic mutations as unique clonal tags (Lee-Six et al., Nature, 2018). These tags allow for retrospective analysis of individual stem cell clones and the construction of phylogenetic trees mapping out stem cell relatedness, with mutations being acquired in a near-linear fashion over the course of an individual's life. The unprecedented level of information obtained in these studies is particularly well-suited to understanding genomic changes in gene therapy trials aimed at curing diseases such as sickle cell disease (SCD). In addition to mapping relatedness between stem cells, sequencing data can be used to better define mutational signatures for HSPC clones that have been successfully gene-modified as well as those that lack an integrated copy of the therapeutic vector. Given this method's ability to identify low frequency mutations in individual HSPC clones, mutations with extremely low variant allele frequencies can be detected much more readily than through traditional bulk sequencing approaches, something that is particularly relevant given recent safety concerns in some SCD gene therapy trials. In this study, we have mapped the clonal dynamics of HSPCs obtained from pre- and post-gene therapy samples from 4 SCD patients who have undergone autologous gene therapy performed using a BCL11A shmiR lentivirus vector (NCT 03282656, 12-36 months follow-up). HSPCs from mobilized peripheral blood (pre-gene therapy), bone marrow aspirates (both pre- and post-gene therapy) or unmobilized peripheral blood (post-gene therapy) were expanded as single clones and 1508 individual colonies were then sequenced using WGS to an average sequencing depth of 12.3x. Initial results indicate that the mean mutation burden per cell in a pre-gene therapy sample is elevated for some patients compared to what would be expected based on patient age in similar studies. In pre-gene therapy samples, the structure of the phylogenetic trees appeared to be highly polyclonal, indicating that there were no significant clonal expansion events prior to gene therapy. In one patient where we undertook extensive profiling, approximately 15-20 excess mutations per HSPC were observed across the entire genome 24 months after transplantation, presumably acquired as a consequence of gene therapy and/or reconstitution post-transplantation, which is equivalent to approximately one year of normal ageing without a transplantation intervention. However, no clonal expansions or driver mutations were identified at this 24 month follow-up timepoint, suggesting that no strong selective advantage or pre-leukemic events were present prior to or following the gene therapy protocol. Extending this approach to a wider range and larger number of patients will allow for comprehensive mapping of the genomic landscape and clonal evolution of stem cells in sickle cell patients and will also set the stage for improved assessment of safety and potential leukemia-initiating events in the context of gene therapy. Disclosures Esrick: bluebird bio: Consultancy. Williams: bluebird bio: Membership on an entity's Board of Directors or advisory committees, Other: Insertion Site Analysis Advisory Board, Patents & Royalties: BCH licensed certain IP relevant to hemoglobinopathies to bluebird bio. The current license includes the potential for future royalty/milestone income. Bluebird has indicated they will not pursue this as a clinical program and BCH is negotiating return of, Research Funding; BioMarin: Membership on an entity's Board of Directors or advisory committees, Other: Insertion Site Advisory Board; Beam Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Scientific Advisory Board; Emerging Therapy Solutions: Membership on an entity's Board of Directors or advisory committees, Other: Chief Scientific Chair; Geneception: Membership on an entity's Board of Directors or advisory committees, Other: Scientific Advisory Board; Alerion Biosciences: Other: Co-founder (now licensed to Avro Bio, potential for future milestones/royalties); Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Steering Committee, Novartis ETB115E2201 (eltrombopag in aplastic anemia). Advisory fees donated to NAPAAC.; Orchard Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Membership on a safety advisory board (SAB): SAB position ended 05/20/2021. Co-founder , Patents & Royalties: Potential for future royalty/milestone income, X-SCID. Provided GMP vector for clinical trial, Research Funding. Campbell: Mu Genomics: Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees. Kent: STRM.bio: Research Funding.

Download Full-text

Clinical and Biomarker Predictors for Avascular Necrosis in Sickle Cell Disease

Blood ◽

10.1182/blood-2021-147829 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3091-3091

Author(s):

Michael Rabaza ◽

Maria Armila Ruiz ◽

Liana Posch ◽

Faiz Ahmed Hussain ◽

Franklin Njoku ◽

...

Keyword(s):

Risk Factors ◽

Sickle Cell Disease ◽

Board Of Directors ◽

Avascular Necrosis ◽

Sickle Cell ◽

Research Funding ◽

Medical Attention ◽

Cell Disease ◽

Advisory Committees ◽

Early Management

Abstract Introduction Sickle cell disease (SCD) affects 1 in 365 African Americans and approximately 25 million people world-wide. A common skeletal system complication is avascular necrosis (AVN), which can cause substantial pain and a reduced quality of life. While early management of AVN is focused on increasing range of motion with physical therapy and pain relief, there are no clear predictors for who is more likely to develop AVN and earlier institution of these preventive measure could help decrease disease progression. Vascular endothelial growth factor (VEGF) is a biomarker of endothelial injury and may indicate reduced vascular supply to the femoral or humeral head. Here we describe potential risk factors and biologic pathways for AVN in SCD, as understanding these may lead to improvements in future monitoring, early detection, and early intervention practices. Methods We investigated clinical and laboratory risk factors associated with AVN in a cohort of 435 SCD patients from our center. Blood samples, clinical, and laboratory data were collected at the time of enrollment during a clinic visit. Genotyping for alpha thalassemia was performed by PCR and the serum concentration of VEGF was measured by ELISA. AVN status was confirmed by review of the medical record and available imaging. We conducted a cross-sectional analysis comparing categorical and linear variables by AVN status using the chi-square and Kruskal-Wallis test, respectively. The independent association of the clinical and laboratory variables with AVN status was determined by logistic regression analysis. The initial model included variables with a P-value < 0.1 on univariate analysis and the final model was ascertained by stepwise forward and backward selection. Median values and interquartile range (IQR) are provided. Results The median age of the cohort was 32 (IQR, 24 - 43) years, 57% (250/435) were female, and 46% (198/435) were on hydroxyurea. AVN was observed in 34% (149/435) of SCD patients. SCD patients with AVN were older, had more frequent vaso-occlusive crises requiring medical attention, and had a higher body mass index (Table I) (P ≤ 0.002). We measured VEGF in 241 of the SCD patients with serum samples available at the time of enrolment. Serum VEGF concentrations trended higher in SCD patients with versus without AVN (420 vs. 359 pg/mL, respectively; P = 0.078). In the multivariate analysis model, AVN was independently associated with increased number of vaso-occlusive crises (OR 1.1, 95% CI: 1.0 - 1.14; P = 0.02), AST concentration (natural log OR 0.5, 95% CI: 0.2 - 0.9; P = 0.03), VEGF concentration (natural log OR 1.4, 95% CI: 1.0 - 1.9; P = 0.047), and tobacco use (OR 1.9, 95% CI: 0.9 - 3.7; P = 0.078). Discussion In conclusion, we demonstrate a high prevalence of AVN in an adult cohort of SCD patients. The presence of AVN was independently associated with a greater frequency of vaso-occlusive pain episodes, which may demonstrate a shared pathophysiology between AVN and vaso-occlusion that merits further investigation. We demonstrate that serum VEGF concentrations are higher in SCD patients with AVN and may be a clinical tool to identify those at high-risk and for earlier intervention for this complication. Figure 1 Figure 1. Disclosures Gordeuk: Modus Therapeutics: Consultancy; Novartis: Research Funding; Incyte: Research Funding; Emmaus: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; CSL Behring: Consultancy. Saraf: Pfizer: Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Download Full-text

Predictors of Maternal Morbidity Among Participants Enrolled in the Sickle Cell Disease Implementation Consortium Registry

Blood ◽

10.1182/blood-2020-140743 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 3-3

Author(s):

Rita V Masese ◽

Dominique Bulgin ◽

Liliana Preiss ◽

Mitchell Knisely ◽

Eleanor Stevenson ◽

...

Keyword(s):

Board Of Directors ◽

Sickle Cell ◽

Research Funding ◽

Transfusion Requirement ◽

The United States ◽

Acute Chest Syndrome ◽

Maternal Outcomes ◽

Maternal Complications ◽

Advisory Committees ◽

Increased Risk

Introduction Pregnancy in sickle cell disease (SCD) is associated with an exacerbation of SCD-related complications and an increased risk of maternal complications. The increased risk is partly due to physiologic adaptations in pregnancy, which include increased metabolic demands and a hypercoagulable state. The maternal death rate for SCD is 629 per 100,000 deliveries, compared to 12 per 100,000 deliveries in black women and 6 per 100,000 deliveries in the general population (Raider et al., 2016). Studies on maternal and perinatal outcomes of patients with SCD present inconsistent and conflicting results. Some studies have reported an increase in maternal complications such as pre-eclampsia, acute chest syndrome and thromboembolic events, while other studies have reported no significant risk in adverse maternal outcomes. The inconsistent findings reported in prior studies may be attributed to small sample sizes and single-centered sites. Our study aims to determine the prevalence and predictors of maternal morbidity among participants enrolled in the SCD Implementation Consortium (SCDIC) registry, which is the largest, most geographically diverse SCD participant sample in the United States. Methods This cross-sectional study included women enrolled in the SCDIC registry who had at least one pregnancy event. The SCDIC is composed of eight academic SCD centers across the United States and one data-coordinating center. Participants were enrolled in the SCDIC registry if they were 18 to 45 years of age and had a confirmed diagnosis of SCD. Enrolled participants completed a series of surveys that collected sociodemographic information, SCD and pregnancy history and data abstractions of participants' medical records was completed. Medical complications queried during pregnancy included: vaso-occlusive episodes, acute chest syndrome, blood transfusion requirement, preeclampsia, maternal diabetes and deep venous thrombosis. Descriptive analysis of sociodemographic, clinical and maternal characteristics was conducted. Bivariate analysis was performed using Chi-Square test, Mann-Whitney U test, t-test, and logistic regressions, as appropriate. A p-value of ≤ 0.05 was considered statistically significant for all analysis. Results The study sample included 743 women who had at least one pregnancy event, and a total of 1066 live births. Almost all women (96.3%) were African American, with a median age of 21 years (inter-quartile range of 19 to 23 years) at first birth. The majority had Hb SS SCD genotype (69.5%; 513 of the 738 with SCD genotype data). Of all reported pregnancies, participants did not use hydroxyurea during conception (78%), and pregnancy (84.5%). Only 2.7 % of the women reported using fertility drugs or assisted reproductive procedures. Seventy five percent of the pregnancies that ended in live births had maternal complications. The leading complications were vaso-occlusive episodes (61.2%), pregnancy requiring blood transfusion(s) (33.2%), preeclampsia (15.4%), deep venous thrombosis (5.6%) and acute chest syndrome (7.7%). When the pregnancies were stratified by SCD genotype, women with Hb SS had a higher occurrence of acute chest syndrome (63.4% vs. 26.7%), transfusion requirement (70.8% vs. 21%) and preeclampsia (66.7% vs 22.4%). In the univariate logistic regressions, multiparous women, with a history of adverse maternal outcomes in a previous pregnancy, had higher odds of vaso-occlusive episodes (OR: 3.42; 95% CI: 2.42-4.94) acute chest syndrome (OR:4.99; 95% CI:2.56- 9.48), transfusion requirement (OR:3.86; 95% CI:2.64- 5.69), and pre-eclampsia (OR:3.36; 95% CI:2.05-5.45). Conclusion In this large multicenter registry, we found pregnant women with SCD have significant maternal complications. Early antenatal care by healthcare providers knowledgeable about risk factors for adverse maternal outcomes in SCD is essential improve maternal and fetal outcomes and reduce the maternal death rate for SCD. Disclosures Hankins: Novartis: Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; MJH Life Sciences: Consultancy, Patents & Royalties; UptoDate: Consultancy; National Heart, Lung, and Blood Institute: Honoraria, Research Funding; LINKS Incorporate Foundation: Research Funding; American Society of Pediatric Hematology/Oncology: Honoraria. Treadwell:Global Blood Therapeutics: Consultancy; UpToDate: Honoraria. King:Amphivena Therapeutics: Research Funding; Bioline: Consultancy; Celgene: Consultancy; Cell Works: Consultancy; Incyte: Consultancy; Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees; Novimmune: Research Funding; RiverVest: Consultancy; Tioma Therapuetics: Consultancy; WUGEN: Current equity holder in private company. Gordeuk:CSL Behring: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; Imara: Research Funding; Ironwood: Research Funding; Novartis: Consultancy. Kanter:SCDAA Medical and Research Advisory Board: Membership on an entity's Board of Directors or advisory committees; AGIOS: Membership on an entity's Board of Directors or advisory committees; BEAM: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; GLG: Honoraria; Jeffries: Honoraria; Cowen: Honoraria; Wells Fargo: Honoraria; NHLBI Sickle Cell Advisory Board: Membership on an entity's Board of Directors or advisory committees; Medscape: Honoraria; Guidepoint Global: Honoraria; bluebird bio, inc: Consultancy, Honoraria; Sanofi: Consultancy. Glassberg:Pfizer: Research Funding; Global Blood Therapeutics: Consultancy; Eli Lilly and Company: Research Funding. Shah:Novartis: Consultancy, Research Funding, Speakers Bureau; Alexion: Speakers Bureau; CSL Behring: Consultancy; Bluebird Bio: Consultancy; Global Blood Therapeutics: Consultancy, Research Funding, Speakers Bureau.

Download Full-text

Hydroxyurea Improves Oxygen Transport Effectiveness in Sickle Cell Anemia Patients

Blood ◽

10.1182/blood.v124.21.2716.2716 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2716-2716

Author(s):

Vivien A. Sheehan ◽

Sheryl Nelson ◽

Caroline Yappan ◽

Bogdan R. Dinu ◽

Danielle Guffey ◽

...

Keyword(s):

Blood Flow ◽

Sickle Cell ◽

Blood Viscosity ◽

Whole Blood ◽

Patient Characteristics ◽

Whole Blood Viscosity ◽

Shear Rates ◽

High Shear Rates ◽

Altered Blood ◽

Low Shear

Abstract Background: Sickle cell disease (SCD) patients have altered blood rheology due to erythrocyte abnormalities, including increased aggregation and reduced deformability, which together affect microcirculatory blood flow and tissue perfusion. At equal hematocrit, sickle cell blood viscosity is increased compared to normal individuals. The hematocrit to viscosity ratio (HVR) is a measure of red blood cell (RBC) oxygen carrying capacity, and is reduced in SCD with clinical consequences related to altered blood flow and reduced tissue oxygenation. Erythrocyte transfusions reduce HVR at low shear rates that mimic venous circulation, and do not change HVR at high shear rates that mimic arterial blood flow. Hydroxyurea is a safe and effective therapy for SCD; however, its effects on sickle cell rheology and HVR have not been fully investigated. Evaluating the effects of hydroxyurea on viscosity is especially critical, before its use is extended widely to patients with cerebrovascular disease or genotypes with higher hematocrit and higher viscosity such as Hemoglobin SC (HbSC). Methods: To determine the effects of hydroxyurea on viscosity and HVR, we designed a prospective study to measure whole blood viscosity at 45 s-1 (low shear) and 225 s-1(high shear) rates in pediatric patients with SCD using a Brookfield cone and plate viscometer under oxygenated conditions. Venous blood samples (1-3mL) were collected in EDTA and analyzed no more than 4 hours after phlebotomy; samples were run in duplicate by persons blinded to the patient’s sickle genotype and treatment status. Laboratory values were obtained using an ADVIA hematology analyzer. Samples were analyzed from three non-overlapping cohorts of patients with SCD and HbAA individuals for comparison: untreated HbSS patients (n= 43), HbSS patients treated with hydroxyurea at maximum tolerated dose (n=98), untreated HbSC patients (n=53) and HbAA patients (n=19). Laboratory parameters that differed significantly among the SCD groups were analyzed by simple linear regression. Results: Patient characteristics and viscosity measurements are shown in the Table. Within the SCD population, the viscosity was lowest among the untreated HbSS patients, presumably due to their low hematocrit, while viscosity was higher in HbSS patients on hydroxyurea and HbSC patients. When the HVR was calculated for each group, no significant difference was identified between untreated HbSS and untreated HbSC patients. However, hydroxyurea treatment significantly increased HVR at both 45s-1 and 225 s-1 (p<0.001), indicating that the slightly increased viscosity in this cohort was more than compensated by a higher hematocrit. Correlations were tested for hemoglobin (Hb), mean corpuscular volume (MCV), white blood cell count (WBC), absolute neutrophil count (ANC), absolute reticulocyte count (ARC), % fetal hemoglobin (HbF), and average red cell density in g/dL with HVR, at both shear rates. The hydroxyurea-associated HVR increase at both shear rates was independent of %HbF or MCV, but the increased HVR at 225 s-1was associated with lower WBC (p<0.001), lower ANC (p=0.002), and lower red cell density (p=.009). Conclusions: We provide prospective data on whole blood viscosity measurements in a large cohort of children with SCD. Hydroxyurea increases the hematocrit in HbSS patients more than the viscosity, and thus improves HVR. These findings imply that hydroxyurea improves RBC oxygen transport at both high and low shear rates, which should confer clinical benefits, and these effects are independent of HbF induction. Concerns about hydroxyurea increasing whole blood viscosity and reducing tissue oxygenation in children with cerebrovascular disease or HbSC patients may not be warranted, if the same beneficial HVR effects are achieved. Abstract 2717. Table 1. Patient characteristics. Viscosity was typically measured in duplicate and averaged for each patient. HVR at 45 s-1 and 225s-1 was calculated as hematocrit/viscosity. Results are presented as mean ± 2SD. HbAAn=19 HbSS, untreatedn=43 HbSS, on Hydroxyurean=98 HbSCn=53 Age (years) 15.4 ± 3.8 10.4 ± 5.1 10.7 ± 3.4 10.5 ± 4.3 Hemoglobin (gm/dL) 13.5 ± 1.7 8.5 ± 1.0 9.9 ± 1.4 11.0 ± 1.2 Hematocrit (%) 40.9 ± 5.3 25.5 ± 3.1 28.4 ± 3.7 31.3 ± 3.2 Viscosity (cP) at 45s-1 5.3 ± 0.9 4.6 ± 1.2 4.3 ± 0.9 5.5 ±0.9 HVR at 45s-1 7.5 ± 0.9 5.8 ± 1.1 6.75 ± 1.0 5.77 ± 0.7 Viscosity (cP) at 225s-1 3.8 ± 0.5 3.3 ± 0.5 3.4 ± 0.5 4.1 ± 0.5 HVR at 225s-1 10.3 ± 0.7 7.7 ± 0.8 8.53 ± 0.8 7.72 ± 0.6 Disclosures Off Label Use: Hydroxyurea is not FDA approved for use in pediatric sickle cell patients.

Download Full-text

Whole blood viscosity and red blood cell adhesion: Potential biomarkers for targeted and curative therapies in sickle cell disease

American Journal of Hematology ◽

10.1002/ajh.25933 ◽

2020 ◽

Vol 95 (11) ◽

pp. 1246-1256 ◽

Cited By ~ 1

Author(s):

Erdem Kucukal ◽

Yuncheng Man ◽

Ailis Hill ◽

Shichen Liu ◽

Allison Bode ◽

...

Keyword(s):

Cell Adhesion ◽

Sickle Cell Disease ◽

Blood Cell ◽

Sickle Cell ◽

Red Blood Cell ◽

Blood Viscosity ◽

Whole Blood ◽

Cell Disease ◽

Whole Blood Viscosity ◽

Potential Biomarkers

Download Full-text

Inhibition of the Proteasome in Bone Marrow-Derived CD138+ Tumor Cells Following Carfilzomib Administration in Relapsed or Refractory Myeloma Patients.

Blood ◽

10.1182/blood.v114.22.1845.1845 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1845-1845

Author(s):

Suzanne Trudel ◽

Susan Lee ◽

Christopher J. Kirk ◽

Nashat Gabrail ◽

Sagar Lonial ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Tumor Cells ◽

Whole Blood ◽

Research Funding ◽

Proteasome Inhibition ◽

Proteasome Activity ◽

Advisory Committees ◽

Post Dose ◽

Blood Samples

Abstract Abstract 1845 Poster Board I-871 Background: Proteasome inhibition is an effective strategy for the treatment of multiple myeloma. In patients, proteasome inhibition has primarily been measured in peripheral blood samples (whole blood or mononuclear cells). However, it is unknown whether myeloma cells in the bone marrow (BM) are equally sensitive to proteasome inhibitors such as bortezomib (BTZ) and carfilzomib (CFZ). Aim: To measure proteasome inhibition in purified tumor cells from BM samples taken from patients enrolled in two ongoing Phase 2 trials of single agent CFZ in relapsed or refractory myeloma: PX-171-003 (003) and PX-171-004 (004). Methods: CFZ was administered as an IV bolus of 20 mg/m2 on Days 1, 2, 8, 9, 15 and 16 of a 28-day cycle on both trials. Bone marrow samples, from an optional sub-study of both trials, were taken during screening and Day 2 (post-treatment) and sorted into CD138+ and CD138− cells. Proteasome activity was measured by an enzymatic assay using a fluorogenic substrate (LLVY-AMC) for the chymotrypsin-like (CT-L) activity and an active site ELISA (ProCISE) to quantitate levels of the CT-L subunits of the constitutive proteasome (Beta5) and immunoproteasome (LMP7) and the immunoproteasome subunit MECL1. Results: Whole blood samples from patients treated with CFZ showed inhibition of CT-L activity of ∼80+, similar to values obtained in Phase 1 studies. A total of 10 CD138+ screening samples, 6 from 004 and 4 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed for proteasome levels and activity. In addition, 15 CD138−screening samples, 7 from 004 and 8 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed. When compared to the average base-line activity, CFZ treatment resulted in 88% CT-L inhibition in CD-138+tumor cells from 004 patients (P = 0.0212 by unpaired t-test) and 59% CT-L inhibition in CD-138+ tumor cells from 003 patients (P = 0.25). Baseline CT-L activity in CD138+ tumor cells was 3-fold higher in 004 than 003, which includes a more heavily pre-treated patient population with greater prior exposure to BTZ. Higher specific enzymatic activity was due to increased levels of both constitutive and immunoproteasomes in tumor cells, where immunoproteasomes account for >75% of total cellular proteasomes. No differences between trials were seen in baseline CT-L activity from non-tumor (CD138−) cells. Inhibition in CD138− cells was 84% (P = 0.0380 and 42% (P = 0.38) in 004 and 003, respectively. Using ProCISE, we measured inhibition of LMP7 (66%), beta5 (48%) and MECL1 (64%) in CD138+ tumor cells from 004 patients. Three patients from 004 and one from 003 had both a screening and post-dose tumor cell samples available for analysis. Inhibition of CT-L activity was >80% in two of the 3 patients on 004; the third patient showed no proteasome inhibition by ProCISE and was unavailable for analysis by CT-L. CT-L activity in the CD138+ tumor cells in the 003 patient was not inhibited, however, inhibition was seen in non-tumor cells. Conclusions: CFZ inhibits the proteasome activity of myeloma cells in the bone marrow of relapsed and refractory myeloma patients. The levels of inhibition were similar to those measured in whole blood samples, supporting the use of the blood-based assay as a surrogate marker for proteasome inhibition in tumor cells. CFZ treatment resulted in inhibition of both CT-L subunits as well as additional subunits of the immunoproteasome in tumor cells. Reduced baseline activity in the more heavily pretreated 003 patients may reflect reduced tumor-dependency on the proteasome and may be related to prior treatment with BTZ in these patients. More samples are needed in order to make correlations between levels of proteasome inhibition in bone marrow tumor cells and prior therapies or response. These observations support further evaluation of proteasome activity and the effects of this promising new agent in primary tumors cells from myeloma patients. Disclosures: Trudel: Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria. Lee:Proteolix, Inc.: Employment. Kirk:Proteolix, Inc.: Employment. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Wang:Proteolix, Inc.: Research Funding. Kukreti:Celgene: Honoraria. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. McDonagh:Proteolix: Research Funding. Zonder:Celgene: Speakers Bureau; Pfizer: Consultancy; Seattle Genetics, Inc.: Research Funding; Amgen: Consultancy; Millennium: Research Funding. Bennett:Proteolix: Employment.

Download Full-text

Ex Vivo Evaluation of Red Blood Cell Adhesion and Whole Blood Thrombosis in Pyruvate Kinase Deficiency

Blood ◽

10.1182/blood-2021-149744 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 923-923

Author(s):

Patrick C. Hines ◽

Xiufeng Gao ◽

Andrew Herppich ◽

Wendy Hollon ◽

Meera B. Chitlur ◽

...

Keyword(s):

Blood Cell ◽

Sickle Cell ◽

Red Blood Cell ◽

Whole Blood ◽

Research Funding ◽

Thrombin Generation ◽

Healthy Controls ◽

Cell Disease ◽

Adhesive Properties ◽

Advisory Committees

Abstract Introduction Pyruvate Kinase Deficiency (PKD) is an inherited glycolytic enzymopathy that is characterized by a life-long chronic hemolytic anemia with severe comorbidities. Hypercoagulability due to increased platelet activity caused by nitric oxide sequestration by cell free hemoglobin has been well-described not just in PKD, but in other hemolytic anemias as well, such as e.g., sickle cell disease (SCD). Hypercoagulability is often accompanied by a cascade of pathophysiological events leading to cell oxidative damage, endothelial activation, and changes in both cell stability and adhesive properties. Increased red blood cell (RBC) adhesion and hypercoagulability may impair microvascular blood flow. Despite these well-recognized rheological changes that are similar to those that occur in other hemolytic anemias, the relationship between baseline erythrocyte adhesion and thrombosis potential have not been well-studied in PKD. Methods 10 PKD subjects and 5 healthy controls were recruited under the IRB-approved protocol from Wayne State University. Flow adhesion of whole blood to vascular cell adhesion molecule-1 (FA-WB-VCAM) was performed by flowing whole blood (1:1 dilution) through a microfluidic channel for 3 minutes (1 dyne/cm 2 shear stress, 1.67Hz pulse frequency). Flow adhesion avidity of the whole blood sample to VCAM-1 (FAAv-WB-VCAM), representing the strength of the RBC-VCAM-1 adhesive interactions, was assessed by quantifying adhesion following sequential increase in shear (5, 10, 20 dyne/cm 2). Thrombin generation assay was conducted using platelet poor plasma with and without thrombomodulin and microparticles (MP) as previously published [1]. Clotting time - reported as lag time (LT), time to peak (ttPeak) and peak height (velocity and amount of net thrombin production), and endogenous thrombin potential (ETP), representing number of substrates potentially convertible by thrombin, were measured. Significance was at p < 0.05. Results FA-WB-VCAM at baseline sample hematocrit was significantly elevated (Figure 1) in PKD subjects (808±377 cells/mm², n=10) compared to healthy controls (6±4 cells/mm², n=4) and even to our previously reported steady state levels in sickle cell samples (290±50 cells/mm² [2]. Thrombin generation profiles were similar between PKD subjects and healthy controls with the exception of the thrombin generation index (PPP+TP/PPP)*100ETP that was significantly (p<<0.01) elevated in citrated plasma of PKD subjects (92.9±6.8) as compared to healthy controls (68.6±11.9). For PKD subjects, FA-WB-VCAM correlated significantly with platelet counts (R²=0.81, p<0.05), and FAAv-WB-VCAM was negatively correlated with platelet (P=0.03, R 2=0.5), but not with erythrocyte-derived microparticles (MP). Platelet-derived MP strongly correlated with thrombin generation (ETP, p<0.01, R 2=0.76) but not with LT or ttPeak of thrombin generation. Red blood cell MP were significantly (p=0.02) decreased in splenectomized patients (200±170, n=7) vs. non-splenectomized subjects (2090±1860, n=3). LT and ttPeak were significantly longer in PKD subjects with thrombosis history than without. Conclusions PKD subjects in this study had elevated RBC adhesive properties similar to that observed in SCD, confirming that pathologic RBC membrane damage resulting in increased adhesion is a common feature of hemolytic anemias. The hemoglobin level of 7.8±1.1 g/dL (mean±SD) for PKD patients was within 6 to 11 g/dl range of hemoglobin levels typical for SCD. There was no significant difference in any other measured parameters (thrombin generation, adhesion avidity, microparticles data). Thrombin generation in PKD subjects was not consistent with hypercoagulability. Based on these observations, pathologic RBC adhesion may be both a novel a mechanism driving hypercoagulability in individuals with PKD. Further studies to determine whether RBC-modifying therapies may decrease thrombosis risk in PKD are warranted. 1. Zia A, Callaghan MU, Callaghan JH, et al. Hypercoagulability in adolescent girls on oral contraceptives - global coagulation profile and estrogen receptor polymorphisms. Am J Hematol, 2015;90:725-31 2. Pittman DD, Hines PC, Beidler D, et al. Evaluation of Longitudinal Pain Study in Sickle Cell Disease (ELIPSIS) by patient-reported outcomes, actigraphy, and biomarkers. Blood. 2021;137(15):2010-20 Figure 1 Figure 1. Disclosures Hines: Functional Fluidics: Current holder of stock options in a privately-held company. Gao: Functional Fluidics: Current Employment. Herppich: Functional Fluidics: Ended employment in the past 24 months. Kwiatkowski: Imara: Consultancy, Research Funding; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Sangamo: Research Funding; Bioverativ: Research Funding; Vertex: Research Funding; Silence Therapeutics: Consultancy; bluebird bio: Consultancy, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Chiesi: Research Funding; CRISPR: Research Funding. Tarasev: Functional Fluidics: Current holder of stock options in a privately-held company.

Download Full-text

Iron Unloading By Therapeutic Phlebotomy in Previously Transfused Children with Sickle Cell Anemia: The Twitch Experience

Blood ◽

10.1182/blood.v128.22.1018.1018 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1018-1018 ◽

Cited By ~ 1

Author(s):

Banu Aygun ◽

Nicole Mortier ◽

Zora R. Rogers ◽

William Owen ◽

Beng Fuh ◽

...

Keyword(s):

Iron Overload ◽

Board Of Directors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Research Funding ◽

Chelation Therapy ◽

Venous Access ◽

Study Entry ◽

Iron Loading ◽

Advisory Committees

Abstract Background: TCD With Transfusions Changing to Hydroxyurea (TWiTCH, ClinicalTrials.gov NCT01425307), an NHLBI-sponsored Phase III multicenter trial, compared transfusions to hydroxyurea for maintaining TCD velocities in children with sickle cell anemia who previously received transfusions for abnormal TCD velocities. Iron overload was treated with serial phlebotomy in children randomized to hydroxyurea. At the first scheduled interim analysis, non-inferiority of hydroxyurea was demonstrated and the study was terminated prematurely. Methods: Participants randomized to hydroxyurea received decreasing volumes of monthly transfusions during hydroxyurea dose escalation to maximum tolerated dose (MTD), averaging 6-7 months. During this transfusion overlap period, no chelation therapy was given. After hydroxyurea MTD was reached, transfusions were discontinued and children started monthly phlebotomy if their entry liver iron concentration (LIC) by MRI-R2 (FerriScan®) was ≥2 mg Fe/g dry weight liver (DWL). The prescribed phlebotomy volume was 10 mL/kg (maximum 500 mL) with adjustments for anemia (5 mL/kg for Hb 8.0-8.5 g/dL and held if Hb <8.0 g/dL). Phlebotomy was performed over 30 minutes with immediate equal volume normal saline replacement, typically using peripheral venous access. LIC was assessed at study entry, midpoint (12 months), and exit (24 months/early closure). Ferritin was monitored monthly using a centralized laboratory. Iron loading calculations were based on actual transfusion and phlebotomy volumes. Results: Sixty children (mean age 9.7±3.2 years; range 5.2-19.0 years; 48% male) were randomized to the Hydroxyurea Treatment Arm. The average duration of previous transfusions was 4.5±2.8 years. Almost all (51/60, 85%) had previously received chelation, primarily deferasirox, and 48 (80%) were on chelation therapy at study enrollment. Hydroxyurea MTD was achieved in 57 children (95%), and 54 commenced phlebotomy (two had low iron burden with LIC <2 and one had Hb <8.0 g/dL). A total of 914 phlebotomy procedures were scheduled per protocol for these 54 children and 756 (83%) were fully completed. There were 77 procedures cancelled due to anemia and another 81 procedures cancelled due to planned anesthesia (16), provider preference (14), hydroxyurea-related cytopenia (13), intercurrent illness (11), inadequate iv access (9), family request (5) or other (13). In 94% of phlebotomy procedures that were initiated, the full volume was removed; for the remaining 6% (47 procedures), a reduced volume was removed due to loss of venous access (37), symptoms such as headache or lightheadedness (7), or other reasons (3). A total of 18 Adverse Events (17 Grade 2 and one Grade 3) occurred in 14 participants in association with phlebotomy (2.3% prevalence). The most common complication was light headedness/near-syncope (6) followed by anemia (4), hypotension (3), headache (3), and pain at the venous access site (1). One subject had a syncopal episode followed by transient weakness, which was centrally adjudicated as TIA. An average of 53.6±21.8 mL/kg blood was administered in the hydroxyurea-treated arm, which calculates to an average iron loading of 40.1±16.3 mg Fe/kg, while an average of 112 mL/kg of venous blood was removed by phlebotomy, which calculates to an average iron unloading of 36.1±15.7 mg Fe/kg. For the 54 children who received phlebotomy, the average LIC was 12.0± 9.7 mg/g at study entry, 13.4±10.3 at midpoint reflecting overlap transfusions without chelation, and 9.7±8.9 at study exit reflecting serial phlebotomy, for an average net LIC decrease of 2.3±4.1 mg/g. Average serum ferritin at study entry was 3105±741 ng/mL and 1392±1542 ng/mL at study exit. For 39 children who completed all 24 months of treatment before study closure, the overall average LIC decrease was 3.2±3.8 mg/gram DWL and 10 had final LIC measurements <3 mg Fe/g. Calculated net iron loading was not significantly associated with measured changes in LIC or ferritin. Conclusions: In the TWiTCH trial, phlebotomy was a feasible, safe, well-tolerated, and effective treatment for transfusional iron overload in children with sickle cell anemia. Although initial overlap transfusions without chelation limited the phlebotomy effects, in children who reached hydroxyurea MTD and discontinued chronic transfusions, monthly phlebotomy led to net iron unloading and lower LIC, and significantly reduced iron burden. Disclosures Rogers: Apopharma: Consultancy. Kalfa:Baxter/Baxalta/Shire: Research Funding. Kwiatkowski:Sideris Pharmaceuticals: Consultancy; Luitpold Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Apopharma: Research Funding; Ionis pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Shire Pharmaceuticals: Consultancy. Wood:World Care Clinical: Consultancy; Biomed Informatics: Consultancy; Biomed Informatics: Consultancy; Celgene: Consultancy; Celgene: Consultancy; AMAG: Consultancy; Apopharma: Consultancy; Apopharma: Consultancy; AMAG: Consultancy; World Care Clinical: Consultancy; Vifor: Consultancy; Vifor: Consultancy; Ionis Pharmaceuticals: Consultancy; Ionis Pharmaceuticals: Consultancy. Ware:Global Blood Therapeutics: Consultancy; Biomedomics: Research Funding; Bayer Pharmaceuticals: Consultancy; Addmedica: Research Funding; Nova Laboratories: Consultancy; Bristol Myers Squibb: Research Funding.

Download Full-text