Abstract: Human parvovirus (HPV) B19, a common infection, frequently causes transient red cell aplasia in children with hemolytic anemia, such as sickle cell disease (SCD). It was considered to be a self‐limited condition, easily treated with blood transfusion. However, acute splenic sequestration, acute chest syndrome, nephrotic syndrome, and stroke have been reported in SCD patients following HPV B19 infection. We report a 3‐year‐old child with SCD who developed fulminant myocarditis following HPV B19‐related aplastic crisis. The diagnosis of myocarditis should be considered in a patient with hemolytic anemia with an infection with HPV B19 who develops signs of cardiopulmonary failure despite correction of anemia. Pediatr Blood Cancer 2007;49:1019–1021. © 2006 Wiley‐Liss, Inc.

Abstract: The hallmark of sickle cell disease (SCD) is pain from a vaso-occlusive crisis. Although ambulatory pain accounts for most days in pain, pain is also the most common cause of hospitalization and is typically treated with parenteral opioids. The evidence base is lacking for most analgesic practice in SCD, particularly for the optimal opioid dosing for patient-controlled analgesia (PCA), in part because of the challenges of the trial design and conduct for this rare disease. Purpose The purpose of this report is to describe our Network’s experiences with protocol development, implementation, and analysis, including overall study design, the value of pain assessments rather than ‘crisis’ resolution as trial endpoints, and alternative statistical analysis strategies. Methods The Improving Pain Management and Outcomes with Various Strategies (IMPROVE) PCA trial was a multisite inpatient randomized controlled trial comparing two PCA-dosing strategies in adults and children with SCD and acute pain conducted by the SCD Clinical Research Network. The specified primary endpoint was a 25-mm change in a daily average pain intensity using a Visual Analogue Scale, and a number of related pain intensity and pain interference measures were selected as secondary efficacy outcomes. A time-to-event analysis strategy was planned for the primary endpoint. Results Of 1116 individuals admitted for pain at 31 participating sites over a 6-month period, 38 were randomized and 4 withdrawn. The trial was closed early due to poor accrual, reflecting a substantial number of challenges encountered during trial implementation. Limitations While some of the design issues were unique to SCD or analgesic studies, many of the trial implementation challenges reflected the increasing complexity of conducting clinical trials in the inpatient setting with multiple care providers and evolving electronic medical record systems, particularly in the context of large urban academic medical centers. Lessons learned Complicated clinical organization of many sites likely slowed study initiation. More extensive involvement of research staff and site principal investigator in the clinical care operations improved site performance. During the subsequent data analysis, alternative statistical approaches were considered, the results of which should inform future efficacy assessments and increase future trial recruitment success by allowing substantial reductions in target sample size. Conclusions A complex randomized analgesic trial was initiated within a multisite disease network seeking to provide an evidence base for clinical care. A number of design considerations were shown to be feasible in this setting, and several pain intensity and pain interference measures were shown to be sensitive to time- and treatment-related improvements. While the premature closure and small sample size precluded definitive conclusions regarding treatment efficacy, this trial furnishes a template for design and implementation considerations that should improve future SCD analgesic trials.

Abstract: Introduction: India has been identified as having the second largest number of births with sickle cell anemia (SCA) in the world after Africa, with estimated 44,400 new-borns affected per year. SCD was previously reported to have a milder course in children from India, with less severe disease among aboriginal tribal populations than in non-tribal populations. Recent reports indicate the occurrence of severe manifestations of SCD in both tribal and non-tribal populations in India. Stroke is one of the serious complications of SCD, but there are no data on transcranial Doppler (TCD) screening for evaluating children with SCD in India who may be at high risk for strokes. The objective of this study was to assess the feasibility of using TCD to measure time averaged maximum of the mean velocities (TAMMV) in the intracranial arteries in children attending a tertiary centre in central India. Methods: STUDY DESIGN: A cross sectional study was conducted in consecutively recruited stable children of either sex with homozygous SCA proven by electrophoresis and high performance liquid chromatography in the age group of 1-26 years. Patients who were febrile, acutely ill, hypoxic or asleep were not included in the study as these conditions can falsely elevate the intracranial blood flow velocities. Patients with hemoglobinopathies other than HbSS or S/b0 Thalassemia and those with a history of congenital neurological illness were excluded. DETERMINATION OF TCD VELOCITY: TCD was performed in a tertiary care center in Nagpur using either an imaging machine (Lasiq s8) in the department of radiology or a portable non-imaging TCD (Compumedics); for both a probe of frequency 2Mhz was used. Maximum values for TAMMV in the Middle (MCA) and Anterior (ACA) cerebral arteries were measured in all; for the non-imaging TCD values for posterior cerebral artery (PCA) and basilar artery were also obtained. The results of the first scan performed on these individuals were included in this study. Using values similar to the STOP trial, TAMMV of each of these vessels were categorized as follows: Normal 〈 = 170cm/s; Conditional - between 170 and 199 cm/s; Abnormal 〉 = 200 cm/s; Low 〈 50 cm/s and unobtainable. MEASUREMENT OF HAEMATOLOGICAL VALUES: Laboratory parameters such as Hemoglobin, white blood cell count (WBC), Mean corpuscular volume (MCV) and hemoglobin F (HbF) levels of the patients in the study were also included if the parameters were available on the day of TCD or within 90 days of TCD study. MEASUREMENT OF HEIGHT, WEIGHT AND BMI: The height and weight of each of the patients on the day of TCD or within a period of 60 days from the TCD were measured and the body mass index (BMI) was calculated. Results One hundred and twenty children and youth aged 1-26 (median 7) years, 67 male (56%), were recruited. Of the 120 patients, 106 (88.5%) belonged to the Scheduled Caste category, 3 (2.5%) to the Scheduled Tribe category and 11 (9.1%) to the Other Classes category. Three (2.5%) had had a clinical stroke and 8 (7%) had had seizures, one of whom also had a stroke. Twenty-seven (23%) children had TAMMV outside the normal range. Five had abnormal TAMMV in the MCA (n=4) and/or ACA (n=1), 8 had conditional TAMMV in the MCA (n=7) and/or ACA (n=1) while 14 patients had low (n=12) or unobtainable (n=2) TAMMV in the MCA. One child with stroke had low TAMMV and one had conditional TAMMV while the third had normal TAMMV. Of the 7 with isolated seizures, one had low TAMMV and one had conditional TAMMV while the remaining 5 were normal. BMI was 8.6-25.3 (median 14.1), height/weight was 3.4-10.3 (median 6.5), hemoglobin was 43-134 (median 81) g/L, oxygen saturation 87-100 (median 99)%, HbF was 1.9-60 (median 21) g/dL, MCV was 59.1-96.7 (median 83.2) fl, WBC was 2.3-35.9 (median 10.1)*109. Those with TAMMV outside the normal range were not different from those with normal TAMMV in terms of age, BMI, Height/weight, or recent hemoglobin, oxygen saturation, HbF, MCV, or WBC. Discussion This study demonstrates the feasibility and importance of TCD screening in Indian SCD population. TAMMV on TCD was outside the normal range in nearly a quarter of children with SCD, as has been reported in studies in other populations. The findings of this study may not be representative of stroke risk in tribal populations since they were underrepresented in this study. These data provide the rationale for implementing systematic screening with TCD to reduce the risk of stroke in children affected by SCD in India. Disclosures Darbari: Novartis: Membership on an entity's Board of Directors or advisory committees; Hilton Publishing: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Other: one day advisory board meeting .

Abstract: Abstract 3809 Background. The role of platelet transfusions in the management of immune thrombocytopenic purpura (ITP) is debatable. The 2010 international consensus guidelines on the diagnosis and management of ITP (Blood, 2010) recommends that platelet transfusions be reserved for use when an urgent restoration in platelet count is needed, such as for patients who are bleeding and those preparing for surgery. To date, the nationwide practices of platelet transfusion in hospitalized ITP patients in the US have not been reported. Objective. This study aims to quantify the current nationwide in-hospital ITP related bleeding complications, platelet transfusion practices and the associated mortality rates. Methods. Data from the Nationwide Inpatient Sample (NIS) 2007, the largest all-payer inpatient database in the U.S. were used. NIS is a powerful database which gives a stratified probability sample of 20% of all hospital discharges among U.S. community hospitals (n = 1,044). Sampling weights were applied to represent all community hospital discharges in the US in 2007. ITP was identified using the ICD9 code 287.31. ITP related major bleed was defined to include intracranial hemorrhage (ICH), gastrointestinal bleed (GIB) and/or genitourinary bleed (GUB). Results. In 2007, there were 50,275±1,596 hospital discharges with ITP as one of the all listed diagnoses. Of these, 4,016±520 were children (≤17years). Platelet transfusions were administered in 14.3±0.6% of the total discharges. Of the pediatric discharges, 4.8±0.9% received platelets. At least one major bleed occurred in 9.0±0.3% of the ITP discharges. Among those with a major bleed, 31.2±1.8% received platelets. Platelet transfusions occurred in 34.9±3.4% of patients with epistaxis, in the absence of a major bleed. The mean age was 45.9±1.3 years for all hospitalized patient with ITP, 60.8±0.8 years for patients with a major bleed, and 58.3±0.7 years for recipients of platelet transfusions. For all patients with ITP, mortality rate was 3.6±2.0%. Mortality rate of 9.5±1.0% among patients with a major bleed, was significantly higher (p 〈 0.001) than those without a major bleed (3.0±0.2%). There was no significant difference in mortality rate (p= 0.12) between patients who had a major bleed and received platelets (11.8±2.0%) and those who had a major bleed and did not receive platelets (8.5±1.5%). Conclusions. These data suggest that platelet transfusions are administered frequently in hospitalized patients with ITP in those who have bleeding complications and also in those who have epistaxis in the absence of a major bleed. Mortality rate is significantly higher in ITP patients with a major bleed as compared to those without a major bleed. Platelet transfusions in patients with major bleeds are not associated with improved mortality rates. The high rate of platelet transfusions with or without concomitant severe hemorrhage suggests the need for further studies to ascertain the role of platelet transfusion in the management of ITP. Disclosures: No relevant conflicts of interest to declare.

Abstract: Background Sickle cell disease (SCD) is caused by abnormal sickle hemoglobin (HbS) and results in chronic hemolytic anemia, painful vaso-occlusive events (VOEs), and progressive vasculopathy that lead to significant morbidity. While acute vaso-occlusive pain is a defining clinical feature, chronic daily pain also contributes significantly to poor quality of life in many adult patients. The ongoing Phase 1/2 HGB-206 Study (NCT02140554) evaluating safety and efficacy of LentiGlobin for SCD (bb1111) gene therapy (GT) uses a modified human β-globin gene that produces GT-derived anti-sickling hemoglobin (HbAT87Q). Data from Group C patients including red blood cell (RBC) physiology, clinical outcomes, and patient-reported pain intensity are presented here. Methods Patients (≥12 and ≤50 years) with SCD and stroke or severe VOEs, including acute episodes of pain and acute chest syndrome (ACS), were enrolled. CD34+ cells collected by plerixafor mobilization/apheresis were transduced with BB305 lentiviral vector. LentiGlobin was infused following myeloablative busulfan conditioning. Patients were monitored for laboratory evaluations including Hb levels and hemolysis markers, SCD-related outcomes, pain intensity using the Patient Reported Outcomes Measurement Information System (PROMIS)-57, and adverse events (AEs). Data are median (min-max) unless otherwise stated. Results As of 3 March 2020, 40 Group C patients (23.5 [12-38] years) initiated cell collection; 25/40 were treated with LentiGlobin and followed for 12.1 (2.8-24.8) months. Neutrophil and platelet engraftment were achieved at 19 (12-27) days and 28 (19-136) days, respectively. All patients stopped RBC transfusions by 90 days post-treatment. In 16 evaluable patients with ≥6 months of follow-up, total Hb at last visit was 11.5 (9.6-16.2) g/dL, with HbAT87Q contribution of 5.2 (2.7-9.4) g/dL, HbS of 6.1 (4.9-7.8) g/dL, and median HbS ≤ 60% of total Hb. Exploratory assays showed near pancellular expression of HbAT87Q ≥6 months post-treatment (N=9 patients), with ~90% of RBCs containing βA-T87Q by 18 months, and reduction in sickling propensity comparable to sickle cell trait. At last visit post-treatment, key hemolysis markers were trending towards normalization with median (quartile [Q] 1-Q3) lactate dehydrogenase of 212 (201-287) U/L, reticulocyte count of 178 (146.5-236.3) ×109/L, and total bilirubin of 19 (15.4-27.4) µmol/L (all for n=25). In 14 patients with ≥6 months of follow-up and history of vaso-occlusive crisis (VOC) or ACS, the annualized VOC+ACS rate was 4.0 (2.0-14.0) in the 2 years prior to treatment. Post-treatment, no ACS or serious VOCs were observed in these patients. One non-serious Grade 2 VOC occurred ~3.5 months after LentiGlobin infusion, resulting in a 99.5% (95% confidence interval, 92.4%-100%) mean reduction in the annualized VOC+ACS rate post-treatment (Figure 1). Patients with PROMIS-57 pain intensity scores "worse" than the population norm at baseline reported clinically meaningful improvements in pain reduction at 12 months post-treatment (n=5). Patients with scores near or "better" than the population norm at baseline (n=5) remained stable over time (Figure 2). The most common non-hematologic Grade ≥3 AEs post-treatment were stomatitis (n=15) and febrile neutropenia (n=11). Serious AEs reported in ≥2 patients post-treatment were nausea, opioid withdrawal syndrome, and vomiting (all for n=2); 3 patients had LentiGlobin-related nonserious Grade ≤2 AEs. There has been one death, unlikely related to LentiGlobin, & gt;18 months post-treatment in a patient with significant baseline SCD-related cardiopulmonary disease. There have been no events of graft failure, vector-mediated replication-competent lentivirus, or clonal dominance. Summary LentiGlobin for SCD GT results in near pancellular βA-T87Q expression and reduced HbS expression, which impacts the pathophysiology of SCD as demonstrated by reduced RBC sickling and hemolysis and increased total Hb. Complete resolution of VOC/ACS was observed in almost all patients, with 99.5% mean reduction in the annualized VOC+ACS rate post-treatment. In addition, patients overall reported an improved pain intensity score. The safety profile post-LentiGlobin remains generally consistent with myeloablative single-agent busulfan conditioning and underlying SCD. Longer follow-up and additional patients will be presented. Disclosures Thompson: CRISPR/Vertex: Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Biomarin: Research Funding; Baxalta: Research Funding; BMS: Consultancy, Research Funding. Walters:AllCells, Inc: Consultancy; Veevo Biomedicine: Consultancy; Editas: Consultancy. Kwiatkowski:Agios: Consultancy; bluebird bio, Inc.: Consultancy, Research Funding; Apopharma: Research Funding; Novartis: Research Funding; Terumo Corp: Research Funding; Sangamo: Research Funding; Celgene: Consultancy; Imara: Consultancy; Bristol Myers Squibb: Consultancy. Aygun:Patient-Centered Outsomes Research Institute: Research Funding; National Heart, Lung, and Blood Institute: Research Funding; National Institute of Nursing Research: Research Funding; bluebird bio: Membership on an entity's Board of Directors or advisory committees, Research Funding. Schmidt:German Cancer Research Center, Heidelberg, Germany: Current Employment; GeneWerk GmbH, Heidelberg, Germany: Other: Equity ownership. DelCarpini:bluebird bio, Inc.: Current Employment, Other: Ownership Interest and Salary. Pierciey:bluebird bio, Inc.: Current Employment, Other: Ownership Interest and Salary. Miller:bluebird bio, Inc.: Current Employment, Other: Ownership Interest and Salary. Gallagher:bluebird bio, Inc.: Current Employment, Other: Ownership Interest and Salary. Chen:bluebird bio, Inc.: Consultancy. Goyal:bluebird bio, Inc.: Current Employment, Other: Ownership Interest and Salary. Kanter:Wells Fargo: Honoraria; Cowen: Honoraria; Jeffries: Honoraria; AGIOS: Membership on an entity's Board of Directors or advisory committees; Medscape: Honoraria; GLG: Honoraria; 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; BEAM: Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy; bluebird bio, inc: Consultancy, Honoraria; Novartis: Consultancy; Guidepoint Global: Honoraria.

Abstract: Introduction: The pan-selectin antagonist rivipansel (GMI-1070) reduced intravascular arrest of red/white blood cell aggregates and improved blood flow and survival in a mouse model of sickle cell disease vaso-occlusive crisis (SCD VOC). In a Phase 1 study of GMI-1070 infusion in SCD adults at steady state (not in VOC), GMI-1070 decreased markers of cellular activation including neutrophil integrins, platelet/neutrophil aggregates, soluble adhesion molecule concentration; and markers of hemostatic activation. Furthermore, in a randomized Phase 2 study of SCD patients, treatment of VOC with GMI-1070 improved clinical outcomes such as time to resolution of crisis, time to discharge, and IV opioid use. Herein we report on the effect of GMI-1070 on biomarkers of cellular and hemostatic cascade activation from this Phase 2 trial. Methods: Patients in VOC enrolled in a prospective, randomized multi-center double-blind Phase 2 trial, ages 12-60 with HbSS or HbSB0thalassemia were treated with GMI-1070 q12h or placebo, in addition to standard treatment per institutional practice, until resolution of VOC. Clinical outcomes and pharmacokinetics have been previously reported (ASH 2013 Abstracts 775, 776, and 2206). Biomarker blood samples were drawn prior to study drug, and on a sparse sampling basis at times starting 30 minutes after initial dose and continuing until 36 hours after the last dose. Analytes measured included: soluble adhesion molecules E-selectin (sEsel), P-selectin, L-selectin, intercellular adhesion molecules 1 and 3, vascular cell adhesion molecule-1; and tissue factor and thrombin-antithrombin complexes by ELISA. At some sites, surface expression of monocyte b2 integrins MAC-1 & LFA-1 and platelet-monocyte aggregates were also measured by flow cytometry. Comparisons were made between the GMI-1070 and placebo groups, and serial expression levels were compared over time. Subgroup analyses were performed by hydroxyurea (HU) use, age group, baseline WBC, and responders' based on clinical outcomes. A mixed effect model was used to test the LS means difference at each time point and ANCOVA model was used to analyze the nadir, peak, and last dose values. Results: ELISA and flow cytometry samples were collected from 70 and 15 subjects, respectively. Soluble E-selectin levels were reduced for the group on GMI-1070 compared to placebo throughout hospitalization, and the differences were statistically significant at some time-points (Figure 1). Baseline sEsel levels were similar; but the peak, nadir, and level at last dose were all lower in the GMI-1070 group (Figure 2). Exploratory subgroup analysis by HU use, age group, response as measured by visual analog scale or opiate use, frequency of VOC in the past, and baseline white blood cell count revealed consistently lower sEsel levels in the GMI-1070 group. Many, but not all, of these differences reached statistical significance. Conclusion: GMI-1070 use during VOC resulted in consistent and significant reductions of sEsel, overall and in sub-groups as compared to placebo. These findings are consistent with the hypothesized effect of GMI-1070 on endothelial activation and/or apoptosis, mediated by inhibition of E-selectin, although an effect on sEsel clearance cannot be excluded. A Phase 3 study is planned to evaluate efficacy and safety of GMI-1070 as treatment for VOC. Soluble E-selectin concentrations may be useful as a biomarker of pharmacodynamic effect. Figure 1: sE-sel was reduced in the GMI-1070 group at all timepoints tested. Comparison to placebo for change from baseline over time is shown. *p 〈 0.05 ***p 〈 0.001 Figure 1:. sE-sel was reduced in the GMI-1070 group at all timepoints tested. Comparison to placebo for change from baseline over time is shown. *p 〈 0.05 ***p 〈 0.001 Figure 2: Figure 2: sE-sel was similar at baseline between GMI-1070 and placebo groups; mean change was different for GMI-1070 compared to placebo at the nadir, peak, and last dose values. Change from baseline is shown. *p 〈 0.05 **p 〈 0.01 Figure 2:. Figure 2: sE-sel was similar at baseline between GMI-1070 and placebo groups; mean change was different for GMI-1070 compared to placebo at the nadir, peak, and last dose values. Change from baseline is shown. *p 〈 0.05 **p 〈 0.01 Disclosures Wun: GlycoMimetics: Research Funding; Pfizer: Steering Committee, Steering Committee Other; Emmaus Medical: Consultancy. Telen:GlycoMimetics: Research Funding; Pfizer: Consultancy; Dilaforette: Research Funding. Krishnamurti:GlycoMimetics: Research Funding. McCavit:GlycoMimetics: Research Funding; Pfizer: Consultancy. DeCastro:GlycoMimetics: Research Funding. Flanner:GlycoMimetics: Employment, Equity Ownership. Kuypers:GlycoMimetics: Research Funding. Larkin:GlycoMimetics: Research Funding. Rhee:GlycoMimetics: Consultancy. Magnani:GlycoMimetics Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Thackray:GlycoMimetics: Employment, Equity Ownership.

Abstract: Background β-globin gene transfer into hematopoietic stem cells (HSCs) could reduce or eliminate sickle cell disease (SCD)-related manifestations. LentiGlobin for SCD gene therapy contains autologous CD34+ cells transduced with the BB305 lentiviral vector (LVV), encoding a human β-globin gene with the anti-sickling T87Q mutation (βA-T87Q). The safety and efficacy of LentiGlobin for SCD is being evaluated in the ongoing Phase 1/2 HGB-206 Study (NCT02140554). The initial 7 patients (Group A) were treated with LentiGlobin made from bone marrow harvested HSCs. The protocol was modified to improve HbAT87Q production by including pre-harvest red blood cell (RBC) transfusions, increasing the total busulfan exposure, and using a refined LentiGlobin manufacturing process (Group B, n=2). An additional modification was made for Group C patients where HSC collection by plerixafor mobilization followed by apheresis was instituted. Data from these Group C patients are discussed here. Results from patients in Groups A and B are reported separately. Methods Patients (≥ 18 years) with severe SCD (including those with recurrent vaso-occlusive crisis [VOC] and acute chest syndrome [ACS] ) were screened for eligibility. Patients received 240 µg/kg of plerixafor 4-6 hours prior to HSC collection via apheresis. CD34+ cells were transduced with BB305 LVV. Patients underwent myeloablative busulfan conditioning and subsequent LentiGlobin drug product (DP) infusion. Patients were monitored for adverse events (AEs), engraftment, vector copy number (VCN), total hemoglobin (Hb) and HbAT87Q expression, hemolysis markers, and SCD clinical manifestations. Data are presented as median (min-max). Results: As of 7 March 2019, 19 Group C patients, aged 26 (18-36) years, had initiated mobilization/apheresis and 13 patients were treated with LentiGlobin for SCD gene therapy. Median DP VCN, % transduced cells, and CD34+ cell dose in the 13 treated patients were: 3.8 (2.8-5.6) copies/diploid genome (c/dg), 80 (71-88) %, and 4.5 (3.0-8.0) x 106 CD34+ cells/kg, respectively. The median follow-up was 9.0 (1.0-15.2) months. Twelve patients achieved neutrophil and platelet engraftments at a median of 19 (15-24) days and 28 (19-136) days, respectively. As of the data cut-off, engraftment was not yet evaluable in 1 patient at 1-month post-infusion. All patients stopped red blood cell (RBC) transfusions within about 3 months post-LentiGlobin gene therapy. Median total hemoglobin (Hb) and Hb fractions in patients at various time points are shown in Figure 1. Median HbS levels were at or below 50% in all patients with at least 6 months follow-up. The median total Hb at last visit in 8 patients with at least 6 months of follow-up, was 11.5 (10.2-15.0) g/dL, with a corresponding HbAT87Q median contribution of 5.3 (4.5-8.8) g/dL and a median HbS 5.7 (4.8-8.0) g/dL. Of these 8 patients, 6 had a history of VOCs or ACS. The median annualized VOC+ACS rate in these patients was 5.3 (3-14) pre-treatment and decreased to 0 (0-2) post-treatment. One Grade 2 VOC was observed 3.5 months post-treatment. No ACS or serious VOCs were observed in Group C patients' post- treatment. Lactate dehydrogenase, reticulocyte count, and total bilirubin at last visit post-LentiGlobin infusion were 225.0 (130.0-337.0) U/L, 150.0 (42.1-283.0) 109/L, 22.2 (3.42-39.3) µmol/L, respectively, trending towards normalization. The most common non-hematologic Grade ≥ 3 AEs were febrile neutropenia (n=10) and stomatitis (n=7) post-DP infusion. Serious AEs were reported in 6 patients post-LentiGlobin treatment, most common being nausea and vomiting. To date, there have been no DP-related AEs or graft failure, vector-mediated replication competent lentivirus detected, or clonal dominance reported. Longer follow-up and additional patient data will be presented. Summary The safety profile of LentiGlobin gene therapy for SCD remains consistent with single-agent busulfan conditioning and underlying disease. Patients in HGB-206 Group C experienced high-level, sustained expression of gene-therapy derived hemoglobin, with median HbS levels reduced to ~50% and median total Hb levels of 11.5 g/dL at 6 months. The cessation of clinical complications (no ACS or serious VOCs) and decreased hemolysis suggest a strong therapeutic effect after LentiGlobin gene therapy in patients with SCD. Disclosures Kanter: Peerview: Honoraria; NHLBI: Membership on an entity's Board of Directors or advisory committees; Rockpointe: Honoraria; SCDAA: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria; Imara: Consultancy; Jeffries: Consultancy; Modus: Consultancy; Guidepoint Global: Consultancy; GLG: Consultancy; Cowen: Consultancy; bluebird bio, Inc: Consultancy; Medscape: Honoraria; Sangamo: Consultancy. Kwiatkowski:Terumo: Research Funding; Novartis: Research Funding; Apopharma: Research Funding; Imara: Consultancy; Celgene: Consultancy; bluebird bio, Inc.: Consultancy, Research Funding; Agios: Consultancy. Schmidt:German Cancer Research Center, Heidelberg, Germany: Employment; GeneWerk GmbH, Heidelberg, Gemrany: Equity Ownership. Miller:bluebird bio, Inc.: Employment, Equity Ownership. Pierciey:bluebird bio, Inc.: Employment, Equity Ownership. Huang:bluebird bio, Inc.: Employment, Equity Ownership. Ribeil:bluebird bio, Inc.: Employment, Equity Ownership. Thompson:Baxalta: Research Funding; Novartis: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; bluebird bio, Inc.: Consultancy, Research Funding. Walters:AllCells, Inc: Consultancy; TruCode: Consultancy; Editas Medicine: Consultancy.