The Oxygenscan: A Rapid and Reproducible Test to Determine Patient-Specific, Clinically Relevant Biomarkers of Disease Severity in Sickle Cell Anemia

Abstract Background: In sickle cell anemia (SCA), hemoglobin S (HbS) polymerizes upon deoxygenation, resulting in sickling of red blood cells (RBCs). These deoxygenated RBCs have strongly reduced deformability, which contributes to the etiology of vaso-occlusive crises and chronic hemolytic anemia. There are no widely available clinical laboratory tests to directly monitor effects of disease modifying therapies (i.e. hydroxyurea) on RBC deformability. RBC deformability can be measured using a Laser Optical Rotational Red Cell Analyzer (Lorrca) ektacytometer (RR Mechatronics, the Netherlands), which measures RBC deformability over a range of osmolalities. Recently, a new module was added which consists of a method to measure RBC deformability, expressed as Elongation Index (EI), during controlled deoxygenation. This test, termed oxygenscan, has 3 key read out parameters: 1) EImax, which represents RBC deformability at normoxia; 2) EImin represents deformability upon deoxygenation; and 3) the point of sickling (PoS), the point at which a >5% decrease in EI is observed during deoxygenation, reflecting the patient-specific pO2 at which sickling begins (Figure 1). In this study, we correlated laboratory parameters associated with SCA disease severity with oxygenscan parameters to establish the clinical utility of this test. Methods: The discovery cohort consisted of 15 SCA patients (median age 22.0 years, 33.3% on hydroxyurea (HU)) enrolled at University Medical Center Utrecht (UMCU). The validation cohort consisted of 21 patients with SCA (median age 12.5 years, 76.2% on HU) from Texas Children's Hematology Center (TCHC). Oxygenscans were carried out in duplicates at both sites. Percentage dense RBC (%DRBC) were measured using an ADVIA hematology analyzer (Siemens) at TCHC only. In this study, we used Pearson's correlation to test for linear correlations between oxygenscan parameters EImax, EImin and PoS and clinically relevant laboratory parameters: total hemoglobin (Hb), absolute reticulocyte count (ARC), %HbS and %HbF, and %DRBC. Results: In both cohorts PoS significantly positively correlated with ARC (Figure 2A-B). In the UMCU cohort, total Hb levels also significantly positively correlated with EImax (Figure 2C), which was validated in the TCHC cohort (Figure 2D). HbF positively correlated with the EImin in both cohorts (Figure 2E-F). EImin also significantly negatively correlated with HbS (r=-0.828 p=<0.001 in the UMCU cohort, r=-0.936, p=<0.001 in the TCHC cohort data not shown). EImax showed a strong negative correlation with the %DRBC (Figure 2G) in the TCHC cohort. Individual test results were highly reproducible at both sites, with a median coefficient of variability of all tested parameters below 3%. Conclusion: The oxygenscan is a semi-automated, inexpensive, highly reproducible, and rapid test to fully characterize patient-specific RBC deformability under a range of oxygen concentrations. Key oxygenscan measurements- PoS, EImin, and EImax- correlated with known measures of SCA disease severity, namely ARC, HbF, HbS, total Hb and %DRBC. Patients with higher reticulocyte counts showed a clinically unfavorable increase of oxygen concentration at which RBCs start to sickle (termed PoS), than patients with lower ARC. Patients with higher HbF had more deformable RBCs even at the lowest oxygen concentrations, or EImin, while patients with higher HbS had lower EImin (low values indicate poor deformability under deoxygenated conditions). Patients with high %DRBC had lower EImax, indicating poor RBC deformability at normoxic conditions. Conversely, patients with high total Hb had high EImax. The very strong correlations of key oxygenscan measurements with different measures of SCA disease severity suggest that these parameters could be exploited as useful biomarkers of clinical severity and in the follow-up and treatment of SCA patients and warrant further investigation. Disclosures Rab: RR Mechatronics: Research Funding. Bos:RR Mechatronics: Research Funding. Cnossen:Roche: Research Funding; CSL Behring: Research Funding; Novartis: Research Funding; Novo Nordisk: Research Funding; Bayer: Research Funding; Shire: Research Funding; Pfizer: Research Funding. Schutgens:Bayer: Research Funding; CSL Behring: Research Funding; Pfizer: Research Funding; Uniqure BV: Research Funding; Novo Nordisk: Research Funding; Baxalta/Shire: Research Funding. van Wijk:Agios Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; RR Mechatronics: Research Funding. van Beers:RR Mechatronics: Research Funding; Bayer: Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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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.

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Outcomes in Children with Severe Vasculopathy from Sickle Cell Anemia after Treatment with Chronic Transfusion, Surgical Revascularization and/or Allogenic Hematopoetic Stem Cell Transplantation

Blood ◽

10.1182/blood-2018-99-118693 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1098-1098

Author(s):

Courtney W. Johnson ◽

Suvankar Majumdar ◽

Andrew D. Campbell ◽

Suresh Magge ◽

Deepika S. Darbari ◽

...

Keyword(s):

Stem Cell ◽

Board Of Directors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Research Funding ◽

Moyamoya Syndrome ◽

Surgical Revascularization ◽

Advisory Committees ◽

Time Of Intervention

Abstract Background: Cerebral vasculopathy is a frequent complication of sickle cell anemia (SCA) and is associated with a high risk for stroke. This vasculopathy seen in SCA can be progressive and severe. Sickle cell patients with severe vasculopathy, including Moyamoya syndrome are at increased risk for neurological disabilities and death. While chronic transfusions decrease the risk of stroke in SCA; unfortunately, progression of vasculopathy can occur despite treatment. Limited data exists regarding long term outcomes for this population. We evaluated effectiveness of three treatment approaches at our center, namely chronic transfusions, surgical revascularization plus chronic transfusions and allogenic hematopoietic stem cell transplant (HSCT). Methods: A retrospective chart review was preformed to identify patients with SCA (hemoglobin SS, Sβ0) and severe vasculopathy including Moyamoya syndrome between 1986 to 2017. Severe vasculopathy was defined as having at least one cerebral artery with > 70% stenosis and/or occlusion as seen on MR angiogram (MRA), CT angiogram (CTA) or conventional angiogram (DSA) as determined by a neuroradiologist at our institution. Patients were identified from an institutional stroke database. Patients were included for analysis if they received at least one of the following: chronic transfusions, surgical revascularization (i.e. encephalo-duro-arterio-synagiosis (EDAS) plus chronic transfusions or HSCT. For HSCT, all graft types (bone marrow, peripheral blood stem cells, umbilical cord blood), conditioning regimens and donor types (related, unrelated and haploidentical) were included. Time to event analyses were performed from the time of intervention (transfusion, HSCT, EDAS/chronic transfusions) using overt clinical stroke, new silent infarcts, progression of vasculopathy or new vasculopathy. Survival curves were analyzed using the log-rank (Mantel-Cox) test. Results: Of 35 patients identified, 54% (n =19) underwent chronic transfusions, 23% (n=8) of patients underwent HSCT after being on chronic transfusions, 23% (n=8) underwent EDAS with chronic transfusions and 1 patient underwent each of the above three modalities (Table 1). Median age at time of intervention was similar for all three cohorts (Table 1). Males were overrepresented in all treatment arms (62.5-79% of patients). Average hemoglobin level prior to intervention was also similar: 7.6 g/dL (IQR 7.1-8.3) for the chronic transfusion cohort, 7.3 gm/dL (IQR 6.3-8.2) for the HSCT cohort, and 7.5 gm/dL (IQR 7.2-8) for the EDAS/chronic transfusion cohort. Absolute reticulocyte count was 492.9 K/ul (IQR 358.4-550) for the chronic transfusion group, 389.4 (IQR 174.3-449) for HSCT, and 250.2 (IQR 107.3-393) for EDAS/chronic transfusions (p=0.08). One patient died of overt stroke in the chronic transfusion cohort. The median follow-up times for the transfusion, HSCT and EDAS plus transfusion groups were 4.4, 2.4 and 6 years respectively. Time from date of intervention (transfusion, HSCT, EDAS) to overt clinical or silent stroke was evaluated (Fig 1). Two of the nineteen patients in the chronic transfusion cohort suffered an overt stroke, while one of eight and two of eight had strokes in the post-HSCT and EDAS plus chronic transfusion cohorts respectively. Fourteen of nineteen (74%) in the chronic transfusion cohort had progression of severe vasculopathy after being on transfusions while two of eight (25%) in the HSCT and four of the eight (50%) patients in the EDAS plus chronic transfusion cohorts had progression. The one patient with all three different interventions did not have additional infarction (clinical or silent) or vasculopathy progression during 1.5 years of follow-up. Conclusions: The risk for cerebral infarction and/or vasculopathy progression after initiation of treatment with either chronic transfusion, HSCT or EDAS is still a major concern. Our data suggest HSCT and surgical revascularization with chronic transfusion provide the greatest benefit in reducing stroke risk and HSCT reduces risk for progression of a severe vasculopathy. Additional, large population studies are needed to clarify the risk. Disclosures Majumdar: NIMHD: Research Funding. Campbell:Functional Fluitics: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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The Oxygenscan Provides Clinically Relevant Biomarkers for Treatment Efficacy That Are Associated with Frequency of Vaso-Occlusive Crisis in Sickle Cell Disease

Blood ◽

10.1182/blood-2019-128870 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2275-2275

Author(s):

Minke A.E. Rab ◽

Richard van Wijk ◽

Celeste K. Kanne ◽

Brigitte A. van Oirschot ◽

Jennifer Bos ◽

...

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Research Funding ◽

Clinical Severity ◽

Patient Specific ◽

Cell Disease ◽

Significant Difference ◽

Before And After ◽

Oxygen Concentrations ◽

Rbc Deformability

Background: In sickle cell disease (SCD), hemoglobin S (HbS) polymerizes upon deoxygenation, reducing red blood cell (RBC) deformability. RBC deformability can be measured over a range of oxygen concentrations using a Laser Optical Rotational Red Cell Analyzer (Lorrca) ektacytometer (RR Mechatronics, Zwaag, the Netherlands) with Oxygenscan module. The Oxygenscan measures 3 key parameters: 1) EImax, RBC deformability at normoxia; 2) EImin, RBC deformability upon deoxygenation; and 3) the point of sickling (PoS): the oxygen tension at which a 5% decrease in normoxic EI is observed during deoxygenation, reflecting the patient-specific pO2 at which sickling begins (Figure 1A). Previously we showed that Oxygenscan parameters correlate with measures of SCD disease severity and hemolysis (absolute reticulocyte count, %fetal hemoglobin, %HbS, total Hb, %dense RBC, (Rab et al. Blood 2018). In this study, we investigated the relationship between oxygenscan parameters and incidence of vaso-occlusive crisis (VOC), and we tested the ability of the Oxygenscan parameters to assess response to hydroxyurea (HU) and chronic transfusion (CTF) in patients with SCD. Methods: We analyzed 2 cohorts: a European cohort (EUC) of 62 SCD patients (all HbSS or HbS/β-thalassemia), enrolled at either University Medical Center Utrecht (UMCU, n= 42) or Hospital Lyon (LIBM, n=20), and a US cohort (USC) of 97 SCD patients enrolled at Texas Children's Hospital (TCH). Differences in Oxygenscan parameters in SCD patients without/with VOC (requiring a doctor's evaluation) in the past 2 years were measured in 46 adult EUC SCD patients and 80 pediatric USC SCD patients. EUC patients without VOC (n=18, median age 40.6 years (y); 11 female (F), 44% on HU, 6% on CTF, 28% on both treatments), were compared to patients with a positive history of VOC (n=28, median age 23.9y, 13F, 39% on HU, 11% on CTF and 11% on both). Patients without VOC in the USC (n= 34, median age 8.0y, 15F, 53% on HU, 15% on CTF and 21% on both treatments) were compared to patients with VOC (n=46, median age 11.8y, 20F, 74% on HU, 13% on CTF and 11% on both treatments). To establish treatment related Oxygenscan parameter changes, we analyzed RBCs from 9 SCD patients from UMCU (median age 19y, 5F), before and during HU treatment (measurements performed at baseline, and 1, 3 and 6 months after starting HU), 7 SCD patients from UMCU (median age 26.7y; 6F) before and after transfusion and 17 SCD patients from TCH (median age 10.8y; 6F) on HU before and after transfusion. Results: In the EUC, PoS differed significantly between patients without VOC in the last 2 years (median 41.6mmHg) and patients with VOC in the last 2 years (median 53.7 mmHg, p<0.001, Figure 1B). In the USC, PoS was also lower in patients without VOC compared to those with a VOC in past 2 years (p<0.05, Figure 1C). EImin in both cohorts was significantly lower in patients who experienced VOC (p<0.05). EImax did not show a significant difference in both cohorts. Correlation of PoS with VOC episodes was significant in the EUC (r=0.447, p<0.01, Figure 1D) and USC (r=0.228, p<0.05), indicating that RBCs start to sickle at a higher pO2 in patients where VOC occur more often. Differences found in median PoS between EUC and USC could be due to differences in treatment (EUC 30% no treatment, USC 5% no treatment), difference in age (EUC median age 28.5y, USC median age 11.6y), genetic background or technical differences between Oxygenscan devices. Transfusion improved EImax, EImin, and PoS (USC: p<0.001, p<0.0001, and p<0.01, EUC: all parameters p<0.05 Figure 1E). HU treatment improved all parameters after 3 and 6 months compared to baseline (p<0.05 and p<0.0001 Figure 1F). Conclusion: Our results show that RBC from SCD patients without VOC in the last two years were able to tolerate lower oxygen concentrations before sickling (PoS). RBCs from patients without VOC were also more deformable when deoxygenated (EImin) compared to patients who had experienced one or more VOCs in the last two years. In contrast, RBC deformability, when oxygenated (EImax) was not different in patients with or without VOC in the last two years. All 3 Oxygenscan parameters significantly improved with standard of care SCD treatments, namely CTF and/or HU. We therefore conclude that the PoS, EImax and EImin are useful biomarkers of clinical severity and treatment response, and may be essential in monitoring novel SCD treatments as part of a clinical trial as a surrogate endpoint. Disclosures Rab: RR Mechatronics: Research Funding. van Wijk:Agios Pharmaceuticals: Consultancy, Research Funding; RR Mechatronics: Research Funding. Bos:RR Mechatronics: Research Funding. Nur:Novartis Pharmaceuticals: Consultancy. Cnossen:NWO: Other: Governmental grants , ZonMW, Innovation fund and Nationale Wetenschapsagenda 2018; Roche: Other: Travel Grants; Takeda: Other: Travel Grants, Research Funding; Shire: Other: Travel Grants, Research Funding; Baxter: Other: Travel Grants, Research Funding; Sobi: Research Funding; CSL Behring: Other: Travel Grants, Research Funding; Nordic Pharma: Research Funding; Novo Nordisk: Research Funding; Bayer: Other: Travel Grants, Research Funding; Pfizer: Other: Travel Grants, Research Funding. van Beers:Agios Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Research Funding; RR Mechatronics: Research Funding.

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Opioid Analgesics Are Associated with Albuminuria in Adult Patients with Sickle Cell Anemia

Blood ◽

10.1182/blood-2019-131368 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2308-2308

Author(s):

Ashley Thrower ◽

Zhou Laura ◽

Vimal K. Derebail ◽

David Wichlan ◽

Ashley Smith ◽

...

Keyword(s):

Board Of Directors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Research Funding ◽

Total Bilirubin ◽

Opioid Analgesics ◽

Cell Disease ◽

Opioid Use ◽

Advisory Committees ◽

Morphine Equivalent

Introduction: Sickle cell disease (SCD) is characterized by hemolytic anemia and vaso-occlusive episodes associated with multi-organ dysfunction. Chronic kidney disease is a common complication and associated with increased mortality. Opioid analgesics are used in SCD patients for pain relief, often starting at a young age and continuing through adulthood. In SCD mouse models, chronic opioid exposure worsens nephropathy leading to increased glomerular mesangial volume and fractional kidney mass as well as albuminuria. We evaluated the association of opioid analgesic use and albuminuria in adult patients with sickle cell disease. Methods: We conducted a cross-sectional study of patients with sickle cell anemia (HbSS and HbSβ0thalassemia) recruited into a prospective natural history cohort at two adult Sickle Cell Centers. Patients were enrolled during routine clinic visits and in a non-crisis, "steady state". We excluded patients with bone marrow or kidney transplant, diabetic nephropathy, hepatitis B or C, HIV, lupus or other glomerular diseases and those on dialysis. We collected data on treatment including use of hydroxyurea and ACE-inhibitors or angiotensin receptor blockers (ACE-I/ARB). Opioid exposure was determined from state narcotic databases for each patient during the year preceding enrollment. Clinical laboratory tests, including spot urine albumin-creatinine ratio (UACR), were acquired at the baseline visit. Patients were considered to have albuminuria if UACR was ≥30mg/g creatinine. Total opioid use, converted to morphine-equivalent units, was quantified in the preceding 1 month, 6 months, and 12 months. Morphine exposure in each time interval was categorized into three groups for analysis: no morphine exposure, exposure ≤50thpercentile, and exposure >50thpercentile. We used multivariable logistic regression models to assess the relationship between opioid use categories and presence of albuminuria adjusting for the following covariates: age, sex, hydroxyurea use, ACE-I/ARB use, total bilirubin, direct bilirubin, hemoglobin, white blood cell (WBC) count, systolic and diastolic blood pressure, hemoglobin F%, estimated glomerular filtration rate (eGFR) and site of enrollment. Results: Seventy-eight patients with sickle cell anemia who had complete data for the variables of interest and outcome were included. Mean age was 33.1 years (SD 11.5) and 45 (57.7 %) were female. When comparing patients by albuminuria status (Table), patients with albuminuria were older (36.1 v 30.8 years) and less likely to be female (45.5 % v 66.7 %). Patients with albuminuria had both higher systolic and diastolic blood pressures. Hydroxyurea use was similar between both groups, but albuminuria patients were more likely to receive ACE-I/ARB therapy. Patients with albuminuria were more likely to have lower hemoglobin, higher total bilirubin, alkaline phosphatase and absolute reticulocyte count. Patients with albuminuria also had lower eGFR and greater opioid exposure over each of the three time intervals evaluated. Opioid use in the preceding 1 month was not associated with albuminuria in the adjusted model (p=0.6). Opioid use in the preceding 6 months was associated with albuminuria (p=0.02), patients with opioid exposure >50thpercentile (>5500 mg of morphine equivalent) having a 39.1 (95% CI: 2.1, 719.8; p=0.01) higher odds of developing albuminuria compared to those without opioid exposure. Patients with less than the 50thpercentile also trended towards a higher odds of albuminuria (OR 6.3, 95% CI: 0.7, 58.1; p=0.1), but did not reach statistical significance. As estimates for odds of albuminuria were similar for patients with > 50thpercentile and ≤50thpercentile of opioid exposure over twelve months of exposure, we collapsed the categories into "no opioid exposure" vs. "any opioid exposure." Patients with any amount of opioid use over the preceding 12 months had a higher odds of albuminuria (OR 11.0, 95% CI 1.2, 104.4; p=0.04). Conclusion: While limited in sample size, our data demonstrate that higher opioid exposure over the preceding 6 months and any opioid exposure in the preceding year were independently associated with albuminuria in patients with sickle cell anemia. These findings suggest that opioid exposure may be associated with kidney disease in patients with SCD. This association warrants additional study given the common use of these agents in SCD. Disclosures Derebail: Retrophin: Consultancy; RTI: Honoraria; Novartis: Consultancy. Ataga:Bioverativ: Honoraria, Membership on an entity's Board of Directors or advisory committees; Emmaus Life Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Research Funding; Modus Therapeutics: Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Results from the Displace Consortium: Practice Patterns on the Use of Transcranial Doppler Screening for Risk of Stroke in Children with Sickle Cell Anemia

Blood ◽

10.1182/blood-2018-99-116709 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4697-4697

Author(s):

Shannon Phillips ◽

Martina Mueller ◽

Alyssa M Schlenz ◽

Cathy Melvin ◽

Robert J. Adams ◽

...

Keyword(s):

Board Of Directors ◽

Sickle Cell ◽

Cerebral Artery ◽

Sickle Cell Anemia ◽

Transcranial Doppler ◽

Research Funding ◽

Practice Patterns ◽

The United States ◽

Care Providers ◽

Advisory Committees

Abstract Introduction: Stroke is one of the most devastating complications of sickle cell anemia (SCA). The STOP (Stroke Prevention Trial in Sickle Cell Anemia) protocol has been adopted by National Heart Lung and Blood Institute (NHLBI) as the guideline for stroke screening using transcranial Doppler ultrasound (TCD) and prevention with chronic red cell transfusion therapy (CRCT). Evidence from the STOP I/II studies indicates the protocol is highly effective, yet wide scale implementation has not been achieved. The DISPLACE (Dissemination and Implementation Looking at the Care Environment) project is a multicenter, NHLBI funded consortium of 28 sites across the United States whose purpose is to identify barriers to the implementation of the STOP protocol and test novel methods for overcoming barriers. The purpose of this study was to use data on practice patterns to evaluate current measurement and practice standards at DISPLACE consortia sites. This abstract presents reported TCD screening and CRCT practices. Methods: A practice patterns survey was sent to the principal investigator (PI) for each DISPLACE site via RedCap ©. PIs were hematology/oncology specialty care providers for children with SCA. Sites represent urban and rural regions, large and small academic institutions, and community-based institutions. The survey was developed by the study investigators; questions were predominantly in a multiple-choice format. Items pertaining to TCD screening included: screening technique (including type of TCD); screening frequency; follow-up for abnormal, conditional, and inadequate results; standard value ranges. Results: All 28 PIs completed the survey. About half of the respondents were female (53.5%). Most identified as White (77.8%), followed by Asian (11.1%) and Black or African American (7.4%). Two identified as Hispanic or Latino (7.4%). Slightly more sites reported using standard TCD (57.1%) versus imaging TCD (TCDi) (42.9%). To calculate the time-averaged mean of the maximum (TAMM) velocities and characterize TCD results, nearly all sites use the middle cerebral artery (96.4%); a majority also use the anterior cerebral artery and/or the terminal internal cerebral artery or distal internal cerebral artery (71.4%). Fewer sites use the posterior cerebral artery (35.7%) or the basilar artery (14.3%). In 7.1% of sites, the radiologist determines which vessels to use during the exam. TCD screening is ordered for children with SCA annually in 92.9% of sites and every 6 months in 7.1% of sites. When TCD screening indicates abnormal TAMM velocities, 85.7% of sites initiate CRCT, 7.1% initiate hydroxyurea (HU) therapy, and 3.6% initiate both HU and CRCT. For additional evaluation, an MRI/MRA is obtained at 64.3% of sites. For high conditional results, the most common action is to initiate HU (67.9%). Other responses include obtaining an MRI/MRA (46.4%) and/or repeating the TCD in 2-4 weeks (25.0%), 6-8 weeks (35.7%), or 12-16 weeks (7.1%). Results deemed inadequate led to repeating the TCD in 2-12 weeks (57.1%) or in one year (3.6%), obtaining an MRI/MRA (57.1%), beginning HU therapy (7.1%), or no repeat TCD or change in management (3.6%). Actions for low conditional results include repeating the TCD (71.4%), obtaining an MRI/MRA (32.3%), and/or initiating HU therapy (57.1%). Surprisingly, sites use different TAMM ranges to characterize the normal/abnormal findings (Table 1). Conclusions: Nearly all DISPLACE sites order TCD screening annually, as recommended in the guidelines, with some ordering screening more frequently. A few sites did not report initiation of CRCT per STOP protocol for abnormal TCD results; however, over half of the sites reported following up with an MRI/MRA, which may suggest evaluating for vasculopathy prior to CRCT. Some sites reported beginning HU therapy for abnormal results; this may reflect consideration of patients for whom CRCT is not possible, but data were not collected for confirmation. Interestingly, results suggest a reliance on MRI/MRA since sites commonly reported ordering neuroradiology studies for abnormal, conditional, and inadequate TCD results. This may suggest an unclear pathway for children with borderline TCD results, and an area for future study. While reported value ranges closely approximated those in the STOP protocol, results indicate sites conducting screening with TCDi may use more conservative values than the validated protocol. Disclosures Phillips: NHLBI: Research Funding. Mueller:NHLBI: Research Funding. Schlenz:NHLBI: Research Funding. Melvin:NHLBI: Research Funding. Adams:NHLBI: Research Funding. Kanter:AstraZeneca: Membership on an entity's Board of Directors or advisory committees; bluebird bio: Membership on an entity's Board of Directors or advisory committees, Research Funding; Global Blood Therapeutics: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sancilio: Research Funding; NHLBI: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Apopharma: Research Funding; ASH: Membership on an entity's Board of Directors or advisory committees.

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Geographic Differences in Phenotype and Treatment of Children with Sickle Cell Anemia from the Multinational DOVE Study

Blood ◽

10.1182/blood.v128.22.3653.3653 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3653-3653 ◽

Cited By ~ 2

Author(s):

Baba Inusa ◽

Raffaella Colombatti ◽

David C Rees ◽

Matthew M Heeney ◽

Carolyn C Hoppe ◽

...

Keyword(s):

Middle East ◽

Board Of Directors ◽

Sickle Cell ◽

North Africa ◽

Sickle Cell Anemia ◽

Research Funding ◽

Acute Chest Syndrome ◽

Advisory Committees ◽

Hospital Visits ◽

Painful Crisis

Abstract Background: Sickle cell anemia (SCA) is characterized by significant phenotypic variability. DOVE1 was a Phase 3, double-blind, randomized, parallel-group, placebo-controlled, multinational study that investigated the efficacy and safety of prasugrel, a P2Y12 adenosine diphosphate receptor antagonist, for reduction of vaso-occlusive crises (VOCs), a composite of painful crisis or acute chest syndrome, in 2- to <18-year-olds with SCA (age cohorts: 2 to <6 years, 6 to <12 years, and 12 to <18 years) (NCT01794000). Methods: DOVE was conducted at 51 sites in 13 countries across 4 continents. A total of 341 subjects were randomized (prasugrel, n=171; placebo, n=170) and SCA genotypes (homozygous hemoglobin S; hemoglobin Sβ0 thalassemia) were included. Eligibility required ≥2 VOCs in the prior year. Baseline clinical and laboratory characteristics and study endpoints were compared by region. Since no overall treatment effect was found, data provided reflect the combined 341 subjects (Americas, N=57; sub-Saharan Africa [SSA], N=148; North Africa/Middle East, N=110; Europe, N=26). Results: Per regional enrollment, the largest proportion of subjects were 6 to <12 years in SSA (48.6% [n=72]), 12 to <18 years in the Americas (45.6% [n=26]) and North Africa/Middle East (58.2% [n=64]), but more evenly divided among the 3 age groups in Europe (30.8-34.6% [n=8-9]). Self-reported racial groupings differed by region (p<0.001): 100% white in North Africa/Middle East; 100% black in SSA; 19.2% white, 76.9% black, and 3.8% multiple in Europe; and 1.8% white, 96.4% black, and 1.8% multiple in the Americas. Mean body mass index was <17 in SSA and Europe (15.3 and 16.6 kg/m2) but >18 in North Africa/Middle East and the Americas (18.3 and 18.1 kg/m2) (p<0.001). Mean blood pressures were lowest in SSA (systolic: 99.0 vs. 105.4-108.0 mmHg, p=0.004; diastolic: 58.3 vs. 60.4-62.9 mmHg, p=0.003). The proportion of subjects with history of acute chest syndrome prior to enrollment was lower in SSA (6.1%) than other regions (18.2-66.7%, p<0.001). Mean number of VOCs in the year prior to enrollment was higher in the Americas than other regions (5.8 vs. 3.2-3.4, p=0.041). Hydroxyurea (HU) use at baseline varied by region: 91.2% in the Americas, 72.7% in North Africa/Middle East, 42.3% in Europe, and 6.8% in SSA (p<0.001). For subjects not on HU at baseline (Table 1), mean hemoglobin at baseline was lowest in SSA (7.6 g/dL); reticulocyte count was lowest in the Americas (214.8 billion/L) and highest in Europe (327.8 billion/L) (p=0.004). For all geographic regions, the most frequent serious adverse events (SAEs) were classified as blood and lymphatic system disorders, with the highest percentage reported as painful crisis. The second most frequent SAEs in SSA, North Africa/Middle East, and Europe were various infections and infestations. The second most frequent in the Americas was respiratory, thoracic, and mediastinal disorders; all were reported as acute chest syndrome. The overall rate of VOCs (events per patient-year) was 3.2 in Europe, 3.0 in the Americas, 2.6 in SSA, and 2.0 in North Africa/Middle East. The percentage of patients hospitalized for VOCs was greatest in Europe (76.9%) compared to other regions (28.4-57.9%); however, mean hospital stay per VOC was similar across regions (5.3-6.2 days). The percentage of VOCs causing hospitalization was highest in Europe (67.7%), followed by North Africa/Middle East (48.7%), the Americas (46.5%), and SSA (26.4%). In SSA, the majority of VOCs were managed as outpatient hospital visits (67.9%), whereas other regions more frequently used inpatient hospital visits (33.2-55.2%). Regardless of region, almost all VOCs were treated with analgesics (overall: 99.5%) and approximately half were treated with intravenous (IV) fluids (overall: 54.4%). In contrast, the proportion of VOC-related transfusions was greater in North Africa/Middle East and Europe (18.6% and 18.8%) than in the Americas and SSA (10.0% and 6.4%). Conclusions: In the DOVE study, management of VOCs with analgesics and IV fluids was similar across regions. However, there were regional differences in VOC-related hospitalizations and transfusions that may reflect differences in culture, utilization of resources, disease severity, or a combination of factors. References: 1Heeney MM, et al. A multinational trial of prasugrel for sickle cell vaso-occlusive events. N Engl J Med. 2016;374:625-635. Disclosures Colombatti: Eli Lilly and Company: Research Funding. Heeney:Eli Lilly and Company: Research Funding; Sancilio and Company: Consultancy, Research Funding; Pfizer: Research Funding. Hoppe:Eli Lilly and Company: Consultancy. Ogutu:Eli Lilly and Company: Research Funding. Hassab:Eli Lilly and Company: Research Funding. Zhou:Eli Lilly and Company: Employment, Other: Minor Shareholder. Yao:Eli Lilly and Company: Employment. Brown:Eli Lilly and Company: Employment, Other: Minor Shareholder. Heath:Eli Lilly and Company: Employment. Jakubowski:Eli Lilly and Company: Employment, Other: Minor Shareholder. Abboud:Eli Lilly and Company: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; MAST Therapeutics: Research Funding; Novartis: Honoraria.

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Splenomegaly in Children with Sickle Cell Anemia Receiving Hydroxyurea in Sub-Saharan Africa

Blood ◽

10.1182/blood-2019-129937 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 993-993

Author(s):

Leon Tshilolo ◽

George A. Tomlinson ◽

Patrick T. McGann ◽

Teresa S. Latham ◽

Peter Olupot-Olupot ◽

...

Keyword(s):

Board Of Directors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Growth Parameters ◽

Sub Saharan Africa ◽

Advisory Committees ◽

Splenic Enlargement ◽

Hydroxyurea Treatment ◽

Lower Blood ◽

Sub Saharan

Introduction. Children with sickle cell anemia enrolled in Realizing Effectiveness Across Continents with Hydroxyurea (REACH, NCT01966731) received open-label hydroxyurea at maximum tolerated dose (MTD) in four countries within sub-Saharan Africa (Tshilolo et al, NEJM 2019;380:121-131). Unlike children in the United States or Europe, a substantial proportion of REACH participants had splenomegaly at enrollment, and more developed splenomegaly while receiving hydroxyurea. Splenic enlargement in association with hydroxyurea treatment in sub-Saharan Africa is previously unrecognized, and its causes and consequences remain unclear. Methods. Palpable splenomegaly was evaluated at both the mid-clavicular and mid-axillary lines at each scheduled and unscheduled sick visit. The size of the spleen, defined as the greatest distance (cm) below the subcostal margin, was recorded in the REDCap trial database at all four clinical sites. Cross-sectional analysis was performed at baseline enrollment using four spleen categories (Not Palpable, 1-4 cm, ≥5 cm, or Splenectomy) with correlations for age, sex, site, growth parameters, alpha-thalassemia trait and G6PD deficiency. This analysis was repeated using the largest spleen size over the first two years on hydroxyurea, but examining two-year laboratory values and also the hydroxyurea dose at MTD, time to MTD, dose-limiting toxicities, and clinical outcomes including acute splenic sequestration, malaria infections, and sepsis. Results. A total of 606 children started hydroxyurea study treatment, including 6 (1.0%) with previous splenectomy, 59 (9.7%) with previous splenic sequestration, and 99 (16.3%) with palpable splenomegaly at enrollment (52 children with 1-4 cm and 47 with ≥5 cm). Large spleens (≥5 cm) were commonly observed at baseline at all clinical sites except Uganda, which identified only 1 child. Compared to those with no palpable spleen, children with large spleens at baseline had similar age and growth parameters, but were significantly more likely to have alpha-thalassemia (78.7% versus 56.2%, P=0.004) and also G6PD deficiency among males (28.0% versus 17.6%, P=0.32). Children with large spleens at enrollment also had a lower hemoglobin (Hb = 6.5 versus 7.3 g/dL, P<0.001) and lower platelet count (platelets = 227 versus 410 x 109/L, P<0.001), but equivalent fetal hemoglobin (HbF = 10.2 versus 9.4%, P=0.82). On hydroxyurea treatment with escalation to MTD, 262 children (43.7%) had palpable splenomegaly recorded, including 120 (20.0%) with spleens ≥5 cm. These large spleens were observed at all four clinical sites, with DRC having the most (52) and Uganda with the least (14). After 24 months of hydroxyurea treatment, laboratory differences were noted according to the cumulative occurrence of splenomegaly including a significantly lower hemoglobin and platelet count, higher absolute reticulocyte count, and lower hydroxyurea dose at MTD (Table). Large spleens were associated with a high cumulative incidence of laboratory dose-limiting toxicities, as well as a significantly higher risk of having clinically symptomatic malaria and receiving blood transfusions (Table). A total of 31 children (5.2%) on hydroxyurea treatment received elective splenectomy, including one partial splenectomy using arterial embolization. Conclusion. Children with sickle cell anemia living in sub-Saharan Africa have an increased risk of having palpable splenomegaly, which is further increased while receiving hydroxyurea treatment. Large spleen at baseline were associated with lower blood counts, consistent with hypersplenism. On hydroxyurea treatment, children with large spleens had significantly lower blood counts and more dose-limiting toxicities, which lowered their eventual hydroxyurea dose at MTD but still led to robust HbF responses. Children with large spleens were also at higher risk of developing malaria infections, receiving transfusions, and requiring surgical splenectomy. Splenic enlargement in association with hydroxyurea treatment was common in children with sickle cell anemia in the REACH trial; its cause remains unclear but the consequences include substantial laboratory toxicity and clinical morbidity. Investigating the etiologies and management of children with chronically enlarged spleens is crucial before expanding hydroxyurea access across Africa for sickle cell anemia. Disclosures Ware: Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Other: Research Drug Donation; Nova Laboratories: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: DSMB; Agios: Membership on an entity's Board of Directors or advisory committees; Addmedica: Other: Research Drug Donation.

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Sickle Stroke Screen: A Patient-Centered Educational Initiative for Children with Sickle Cell Anemia in the Displace Consortium

Blood ◽

10.1182/blood-2020-141963 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 43-44

Author(s):

Alyssa M Schlenz ◽

Shannon Phillips ◽

Martina Mueller ◽

Cathy L Melvin ◽

Robert J Adams ◽

...

Keyword(s):

Needs Assessment ◽

Board Of Directors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Stroke Prevention ◽

Stroke Risk ◽

Advisory Board ◽

Educational Initiative ◽

Advisory Committees ◽

Board Membership

Introduction: The NHLBI funded Dissemination and Implementation of Stroke Prevention Looking at the Care Environment (DISPLACE) study was designed to improve implementation of stroke prevention guidelines in children with sickle cell anemia (SCA), particularly implementation of transcranial Doppler (TCD) ultrasound for identifying individuals at risk of stroke. The study consists of 3 phases: 1) evaluating current stroke risk screening practices, 2) exploring barriers and facilitators to guideline implementation (needs assessment), and 3) designing and implementing interventions to improve stroke risk screening. A key barrier identified through qualitative methods during the needs assessment was a gap in education, including an overall lack of understanding among patients and caregivers of the purpose of TCD screening. This abstract describes the process of developing one of the interventions for phase 3, a rebranding and educational initiative. Methods: During the needs assessment, 27 key informant interviews and 173 complete surveys were conducted with individuals with SCA and their caregivers. Transcripts from the interviews and survey responses were reviewed to better understand the extent of educational gaps described by families as well as to guide initial rebranding prototypes. Prototypes were developed by the study team, including a new name and logo for TCD as well as an infographic. An interview guide was then created to obtain feedback on the prototypes from individuals with SCA and/or the parent or primary caregiver from two sites in the consortium. Cue cards with prototypes were included with prompts for the "think aloud" method to be applied during interviews. Cue cards were presented first with prototypes for the new name in black font on a white background to solicit feedback on the wording alone. Then, cue cards included various layouts, fonts, and graphics with the prototype names for in-depth feedback on the logo appearance. Finally, participants were asked questions pertaining to the infographic. Results: Twenty interviews were conducted with individuals with SCA and/or the parent/caregiver at two DISPLACE sites. Almost all participants (95%) made the connection between the wording prototypes and TCD without prompting. Many participants expressed that the word "stroke" in both options was "scary," and sometimes chose the option that was "less scary to them." However, many participants also felt that the word "stroke" was necessary to explain the reason for the procedure and would prompt families to ask about the screening as opposed to making them more fearful. The majority of participants (60%) chose "Sickle Stroke Screen" over "Stroke Risk Screen." Participants reported preferring this wording because it is specific to SCA, was easier to remember and represented a less "scary" option. The most commonly preferred logo is presented in Figure 1. Participant reasons for selecting this option were: it is easier to read; they preferred the stacked layout; it is less spread out; they liked the bold letters; it is more eye catching; and it includes the words "sickle cell" in the logo. When asked about preferences for an infographic, the majority described including a picture of a brain. Nearly all participants believed a reassuring message was needed to balance out the fear of the word "stroke." The message, "knowledge is power" provided this balance and resonated with nearly all participants (95%). Figure 2 presents the infographic developed based on participant feedback. Conclusions: Results from this educational rebranding effort highlight the importance of understanding patient and family educational gaps and incorporating their perspective and feedback into educational campaigns. The new logo and infographic were integrated into an educational pamphlet, informative posters and other material designed by the DISPLACE site principal investigators. Part 3 of the study is underway including implementation of the educational initiative at the DISPLACE sites. The new terminology and logo have also been broadly distributed throughout the US through community-based organizations to other patients, families, and stakeholders. Disclosures Kanter: AGIOS: Membership on an entity's Board of Directors or advisory committees; NHLBI Sickle Cell Advisory Board: Membership on an entity's Board of Directors or advisory committees; SCDAA Medical and Research Advisory Board: Membership on an entity's Board of Directors or advisory committees; Wells Fargo: Honoraria; Jeffries: Honoraria; Cowen: Honoraria; bluebird bio, inc: Consultancy, Honoraria; Novartis: Consultancy; Sanofi: Consultancy; Medscape: Honoraria; Guidepoint Global: Honoraria; GLG: Honoraria; BEAM: Membership on an entity's Board of Directors or advisory committees.

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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.

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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.

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