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Beta-thalassemia is one of the most common monogenic disorders. Standard treatment of the most severe forms, i.e., transfusion-dependent thalassemia (TDT) with long-term transfusion and iron chelation, represents a considerable medical, psychological, and economic burden. Allogeneic hematopoietic stem cell transplantation from an HLA-identical donor is a curative treatment with excellent results in children. Recently, several gene therapy approaches were evaluated in academia or industry-sponsored clinical trials as alternative curative options for children and young adults without an HLA-identical donor. Gene therapy by addition of a functional beta-globin gene using self-inactivating lentiviral vectors in autologous stem cells resulted in transfusion independence for a majority of TDT patients across different age groups and genotypes, with a current follow-up of multiple years. More recently, promising results were reported in TDT patients treated with autologous hematopoietic stem cells edited with the clustered regularly interspaced short palindromic repeats-Cas9 technology targeting erythroid BCL11A expression, a key regulator of the normal switch from fetal to adult globin production. Patients achieved high levels of fetal hemoglobin allowing for discontinuation of transfusions. Despite remarkable clinical efficacy, 2 major hurdles to gene therapy access for TDT patients materialized in 2021: (1) a risk of secondary hematological malignancies that is complex and multifactorial in origin and not limited to the risk of insertional mutagenesis, (2) the cost—even in high-income countries—is leading to the arrest of commercialization in Europe of the first gene therapy medicinal product indicated for TDT despite conditional approval by the European Medicines Agency.

Because of chronic anemia, hypogonadotropic hypogonadism, and iron chelation, pregnancy in homozygous and heterozygous compound beta-thalassemia patients stays a challenge. Pregnancies of transfused beta-thalassemia women registered in the French National Registry, conducted between 1995 and 2015, are described. These pregnancies were compared with pregnancies in healthy women and to data previously published in the literature. Fifty-six pregnancies of 37 women were studied. There were 5 twin pregnancies. Assisted reproductive technologies (ART) were used in 9 pregnancies. Median term at delivery was 39 amenorrhea weeks, and median weight at birth was 2780 g. Cesarean section was performed in 53.6% of the pregnancies. There were 6 thromboembolic events, 6 serious infections, 6 pregnancy-induced hypertensions (PIH), 6 intrauterine growth retardations (IUGR), 5 severe hemorrhages, 4 gestational diabetes, 3 alloimmunizations, 2 heart diseases, and 1 pre-eclampsia. There were 5 infections and 4 osteoporosis in the first year of post-partum. ART and cesarean sections were more often used in the beta-thalassemia group, compared to control subjects. Thromboembolic events, PIH, hemorrhage at delivery, and IUGR were more frequent in the beta-thalassemia group. Time to delivery was not different, but infant weight at birth was significantly smaller in the beta-thalassemia group. In the post-partum period, global maternal complications were more frequent in the beta-thalassemia group. Pregnancy in transfused beta-thalassemia women is safe with rare obstetrical and fetal complications. Cesarean section remains often chosen, and infant weight at birth remains smaller than that in the general population, despite delivery at full term.

β-thalassemia is an haemoglobinopathy characterized by a defective synthesis of the β-globin chain. To assess the current state of health of paediatric patients with β-thalassemia, data from the French national registry regarding children born between 2005 and 2020 with β-thalassemia intermedia (TI) or major (TM) were collected. A total of 237 patients (median age 7.1 years at last visit) were analysed, of whom 156 (65.8%) were born in France and 162 (68.4%) had a TM phenotype. The probability of survival for children with TM born in France was 98.3% at 15 years. Fifty-four (22.8%) children received a haematopoietic stem cell transplant with a success rate of 88.8%. Hepatic and cardiac iron overload monitoring in non-transplanted patients showed moderate overload in 15.7% (18/115) and 7.1% (7/99) of cases, respectively, while clinical complications were found in only 4 patients with TM (hepatic in 3 cases). At last visit, mean ferritinemia was 1293 ng/ml (±759). Overall, less than 10% of children underwent splenectomy. No significant impact of the disease on growth or academic achievement was observed. Deferasirox was the main first-line chelator, prescribed in 78.2% of cases, with side effects reported in 11.7% of instances.

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INTRODUCTION: Because of iron overload complications, thrombosis and infectious predisposition, patients with severe forms of thalassemia are likely to be at increased risk of COVID-19 complications. RESULTS: A national survey conducted during the year 2020 across the French reference centers for hemoglobinopathies identified 16 cases of COVID-19 confirmed by RT-PCR in beta-thalassemia patients. Their age ranged from 11 months to 60 years. 15 patients were transfusion-dependent and 6 were splenectomized. Concerning iron overload related complications, none had diabetes or cirrhosis and only one had experienced heart failure. All 4 pediatric patients were pauci-symptomatic during the viral episode. Three patients (41, 49 and 57 years old) developed COVID-19 pneumonia requiring oxygen therapy without the need for mechanical ventilation. Neutropenia (absolute neutrophils count

Introduction Betibeglogene autotemcel (beti-cel; LentiGlobin for β-thalassemia) gene therapy is being evaluated for the treatment of transfusion-dependent β-thalassemia (TDT). Initial positive results of beti-cel in the phase 3 studies, HGB-207 (NCT02906202; non-β0/β0 genotypes) and HGB-212 (NCT03207009; β0/β0, β0/β+ IVS-I-110 and β+ IVS-I-110/β+ IVS-I-110 genotypes), showed 10/12 adult patients achieved transfusion independence. The studies expanded enrollment to include adolescents and children. We present interim results from pediatric patients Methods After mobilization and apheresis, autologous CD34+ cells were transduced ex vivo with BB305 lentiviral vector, containing a modified human β-globin gene to produce beti-cel drug product (DP). Patients underwent busulfan myeloablation and infusion with beti-cel and were then followed longitudinally. Transfusion independence (TI; weighted average hemoglobin [Hb] ≥9 g/dL without transfusions for ≥12 mo) was the primary endpoint in HGB-207 and a secondary endpoint in HGB-212. Transfusion reduction (≥60% reduction in transfusion volume between Month 12 to 24 versus baseline) is the primary endpoint in HGB-212. Hb levels, TI characteristics, and quality of life were secondary endpoints. Assessments of ineffective erythropoiesis were exploratory. Data presented as median (min-max). Results Twenty-four pediatric patients were treated including 13 patients 3 mo follow-up achieved platelet engraftment and had platelets ≥100 x109/L by Month 12; one 17-yr old patient did not have platelets ≥100 x109/L until Month 15. In HGB-207, 6/7 (86%) patients 3 mo follow-up have stopped transfusions for ≥6 mo. TI was achieved in 3/4 (75%) evaluable patients In HGB-212, 3/5 (60%) patients 3mo follow-up have stopped transfusions for ≥6 mo. TI was achieved in 1/2 evaluable patients Post-infusion non-hematologic grade ≥3 adverse events (AEs) in ≥3 patients aged Summary Interim results in HGB-207 and HGB-212 show that after treatment with beti-cel, pediatric patients Disclosures Thompson: CRISPR/Vertex: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Baxalta: Research Funding; BMS: Consultancy, Research Funding; Biomarin: Research Funding; bluebird bio, Inc.: Consultancy, Research Funding. Kwiatkowski:Novartis: Research Funding; Agios: Consultancy; Sangamo: Research Funding; bluebird bio,Inc.: Consultancy, Research Funding; Apopharma: Research Funding; Imara: Consultancy; BMS: Consultancy; Terumo Co: Research Funding; Celgene: Consultancy. Porter:Vifor Pharmaceuticals: Honoraria; bluebird bio, Inc.: Consultancy, Honoraria; Agios Pharmaceuticals: Consultancy, Honoraria; La Jolla Pharmaceuticals: Honoraria; Silence Therapeutics: Honoraria; Protagonist Therapeutics: Honoraria; BMS: Consultancy, Honoraria. Kulozik:Novartis: Consultancy, Honoraria; bluebird bio, Inc.: Consultancy, Honoraria. Thrasher:Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership; Orchard Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership; 4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees. Thuret:Novartis pharma: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials. Lal:Insight Magnetics: Research Funding; Celgene, BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Terumo Corporation: Research Funding; Agios Pharmaceuticals: Consultancy; Chiesi USA: Consultancy; La Jolla Pharmaceutical Company: Research Funding; bluebird bio, Inc.: Research Funding; Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding. Guo:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Liu:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Colvin:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Walters:Veevo Biomedicine: Consultancy; AllCells, Inc: Consultancy; Editas: Consultancy. Locatelli:Jazz Pharmaceeutical: Speakers Bureau; Medac: Speakers Bureau; Miltenyi: Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Introduction We investigated the impact of β-thalassemia genotypes and disease genetic modifiers including HBA and KLF1 genotype and sentinel single-nucleotide polymorphism (SNP) genotypes at 3 major HbF quantitative trait loci (QTL) on clinical outcomes of TDT patients treated with beti-cel gene therapy in two phase 3 studies, HGB-207 (NCT02906202) and HGB-212 (NCT03207009). Methods HBA deletions and triplications were determined by gap-polymerase chain reactions. HBG2 (including rs7482144, Xmn1 site) and HBG1 promoters, HBA2, HBA1, and KLF1 underwent individual nucleotide sequencing. Multiplex amplification refractory mutation system (ARMS) tests were used to identify HbF QTL SNPs (rs10128556 in HBBP1; rs766432, rs1427407, rs10189857 in BCL11A; rs9399137, rs66650371 in HMIP). Thalassemia severity score (TSS) was calculated as defined by Danjou et al, Haematologica, 2015, considering gender, HBB and HBA genotypes, and 4 SNPs in HbF QTL (HBG2, BCL11A, HMIP). Correlative analyses were performed to assess relationships between genotype, presence/absence of non-HBB mutations (HBA2, HBA1, KLF1), presence/absence of HbF QTL SNPs (HBG2, BCL11A, HMIP), and TSS with the achievement of transfusion independence (TI; weighted average hemoglobin [Hb] ≥9 g/dL without red blood cell [RBC] transfusions for ≥12 months). Correlation coefficients used percentage bend correlation. Statistical significance threshold was p ≤ 0.05. Results As of 3 March 2020, 38 patients were treated in HGB-207 and HGB-212 (β0/β0 genotype n=9; non-β0/β0 genotype n=29 [β+/β+ n=8; β0/β+ n=15; βE/β0 n=6]). All patients were heterozygous or homozygous for mutations or SNPs that may modulate disease severity; 20 patients were homozygous for ≥1 mutation or SNP. Patients had the following alleles associated with higher HbF synthesis: HBG2 rs7482144 C>T (Xmn1 site), C/T n=9, T/T n=1; BCL11A rs1427407 G>T, G/T n=8; BCL11A rs10189857 A>G, A/G n=16, G/G n=18; HMIP rs9399137 T>C, T/C n=9, C/C n=2. Three patients were heterozygous for single α-globin gene deletion (-α/αα) and 2 were heterozygous for α-globin gene triplication (αα/ααα). Median TSS was 3.65 (min - max 0.4 - 8.1). TI was achieved by 23/27 (85%) evaluable patients; 4 patients with ≥ 12 months follow-up have been transfusion free for > 10 months but were not yet evaluable for TI (Figure). β-thalassemia genotype did not strongly correlate with TI (two-sided Fisher's Exact Test, p-value = 0.78). Month 12 median (min - max) peripheral blood vector copy number (PB VCN) was 1.5 (0.2 - 5.0) c/dg in TI or transfusion-free patients (n=27) and 0.2 (0.2 - 0.4) c/dg in patients who did not achieve TI (n=4). The transfusion-free patient (β0/β0) with the lowest month 12 PB VCN was homozygous for T/T at rs7482144 (HBG2Xmn1 site) and G/G at rs10189857 (BCL11A), and heterozygous for single α-globin gene deletion. Endogenous Hb (5.9 g/dL HbF + 0.2 g/dL HbA2) and gene therapy-derived HbAT87Q (4.4 g/dL) at month 12 enabled this patient to stop transfusions. Tests of association of SNPs and mutations with TI were not significant; no p-value < 0.31 (chi-squared test). As only 4 patients did not achieve TI, the power to detect an association was limited. Larger sample sizes are needed to determine if individual SNPs and mutations may have an impact on TI. In TI or transfusion-free patients (n=27), TSS correlated strongly with month 12 endogenous unsupported Hb (HbA + HbA2 + HbF + HbE without RBC transfusions for 60 days) (correlation coeff. = -0.76, p < 0.0001), but not with HbAT87Q (correlation coeff. = 0.26, p = 0.19) or unsupported total Hb (correlation coeff. = 0.32, p = 0.10). Beti-cel-related adverse events (AE) in >1 patient were abdominal pain (n=2 non-β0/β0; n=1 β0/β0), thrombocytopenia (n=3 non-b0/b0). Serious AEs in ≥3 patients post-infusion were thrombocytopenia (n=2 non-β0/β0; n=1 β0/β0), pyrexia (n=1 non-b0/b0; n=2 β0/β0), veno-occlusive disease (n=3 non-β0/β0). Summary Genetic characterization of TDT patients treated with beti-cel revealed diverse HBB and non-HBB mutations and polymorphisms that may influence disease severity. Higher PB VCN and HbAT87Q levels were associated with increased likelihood of TI. In instances of lower HbAT87Q, higher endogenous HbF might be a determinant in whether TI is achieved. Despite genetic heterogeneity, beti-cel enabled patients to achieve TI regardless of β-thalassemia genotype, TSS, disease genetic modifiers including HBA, and HbF QTL SNP genotypes. Disclosures Walters: Veevo Biomedicine: Consultancy; AllCells, Inc: Consultancy; Editas: Consultancy. Chui:bluebird bio, Inc.: Other: Payment for lab use for the sequencing analyses done for the studies. Lal:bluebird bio, Inc.: Research Funding; Agios Pharmaceuticals: Consultancy; Celgene, BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; La Jolla Pharmaceutical Company: Research Funding; Novartis: Research Funding; Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Terumo Corporation: Research Funding; Chiesi USA: Consultancy; Insight Magnetics: Research Funding. Locatelli:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharmaceeutical: Speakers Bureau. Kwiatkowski:bluebird bio, Inc.: Consultancy, Research Funding; Agios: Consultancy; Apopharma: Research Funding; Bristol Myers Squibb: Consultancy; Imara: Consultancy; Celgene: Consultancy; Sangamo: Research Funding; Terumo Corp: Research Funding; Novartis: Research Funding. Porter:bluebird bio, Inc.: Consultancy, Honoraria; Vifor Pharmaceuticals: Honoraria; La Jolla Pharmaceuticals: Honoraria; Protagonist Therapeutics: Honoraria; Agios Pharmaceuticals: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Silence Therapeutics: Honoraria. Thuret:Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis pharma: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials. Kulozik:Novartis: Consultancy, Honoraria; bluebird bio, Inc.: Consultancy, Honoraria. Thrasher:4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership; Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership. Yannaki:bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Speakers Bureau; SANDOZ: Speakers Bureau; Gilead: Speakers Bureau. Yang:bluebird bio,Inc.: Current Employment, Current equity holder in publicly-traded company. Whitney:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Petrusich:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Colvin:bluebird bio, Inc.: Current Employment, Current equity holder in publicly-traded company. Thompson:BMS: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; CRISPR/Vertex: Research Funding; Biomarin: Research Funding; Baxalta: Research Funding.

Allogeneic stem cell transplantation remains the only curative treatment for sickle cell anemia (SCA), but the place of myeloablative conditioning in the procedure remains to be defined. The aim of the present study was to analyze long-term outcomes, including chimerism, SCA-related events and biological data (hemoglobin, reticulocytes, HbS%), and fertility in a French series of 234 SCA patients under 30 years of age who, from 1988 to 2012, received a matched-sibling-donor stem cell transplantation following standardized myeloablative conditioning [busulfan, cyclophosphamide and rabbit antithymocyte globulin (ATG)]. Since the first report of the series (1988-2004), 151 new consecutive patients with SCA have been similarly transplanted. Considering death, non-engraftment or rejection (donor cells 15 years (hazard ratio=4.37; P=0.002) and lower (5-15 vs. 20 mg/kg) ATG dose (hazard ratio=4.55; P=0.001). At one year, 44% of patients had mixed chimerism (5-95% donor cells), but those prepared with ATG had no graft rejection. No events related to SCA occurred in patients with mixed chimerism, even those with 15-20% donor cells, but hemolytic anemia stigmata were observed with donor cells

Introduction: Transfusion-dependent β-thalassemia (TDT) is a severe genetic disease requiring lifelong, regular packed red blood cell (pRBC) transfusions and iron chelation treatment. Betibeglogene autotemcel (beti-cel) is a one-time ex vivo gene therapy that addresses the underlying cause of TDT to potentially enable lifelong, stable production of modified adult hemoglobin (Hb) sufficient to achieve transfusion independence (TI). Patients (pts) with TDT (N=63) were treated with beti-cel in 2 completed phase 1/2 studies (HGB-204, HGB-205) and 2 ongoing phase 3 studies (HGB-207, HGB-212). After 2 y of follow-up, pts could enroll in a long-term follow-up study (LTF-303 [NCT02633943]) for up to an additional 13 y. We report results from LTF-303 in pts with up to 7 y of follow-up. Methods: Pts underwent single-agent, pharmacokinetic-adjusted busulfan myeloablation and were infused with autologous CD34+ cells transduced with BB305 lentiviral vector. The phase 3 studies used a refined transduction process compared with the phase 1/2 studies. LTF-303 assessments included transfusion status, Hb, iron overload, and safety. Around the time of beti-cel infusion, pts stopped iron chelation; however, chelation could be resumed post-infusion at the physician's discretion. A subanalysis was conducted to assess iron status in pts who restarted then stopped chelation. Pts who achieved TI and had a minimum of 9 mo of follow-up after discontinuation of chelation were included in the subanalysis to assess iron parameters while off chelation. Data are reported as median (min-max) unless otherwise stated. Results: As of March 9, 2021, LTF-303 enrolled 51 pts (phase 1/2: 22 pts; phase 3: 29 pts), of which 55% were female; the median age was 19 (7-35) y. Post-infusion follow-up was 44.2 (22.9-86.5 mo; 1 pt had their Month 24 visit at 22.9 mo). TI (weighted average Hb ≥9 g/dL without pRBC transfusions for ≥12 mo) was achieved in 15/22 (68%) pts treated in the phase 1/2 studies and in 25/29 (86%) pts treated in the phase 3 studies (all during parent study); at last follow-up, all pts had remained TI for 32.2 (13.1-84.1) mo. Median (Q1, Q3) gene therapy-derived Hb (HbA T87Q) in pts treated in the phase 1/2 studies who achieved TI was stable over time: 7.3 (5.4-8.4) g/dL at Month 24 (n=15) and 7.6 (6.6-9.3) g/dL at Month 72 (n=7). Median (Q1, Q3) HbA T87Q in pts treated in the phase 3 studies was also stable: 9.1 (8.5-10.3) g/dL at Month 24 (n=24) and 9.9 (9.8-10.0) g/dL at Month 42 (n=2). HbA T87Q helped to sustain total Hb. Total Hb was a median (Q1, Q3) of 10.0 (9.7-11.8) g/dL at Month 24 and 10.5 (10.3-12.1) g/dL at Month 72 in phase 1/2 studies and 12.1 (10.8-13.1) g/dL at Month 24 and 12.2 (11.7-12.8) g/dL at Month 42 in phase 3 studies. Pts who achieved TI (n=40) experienced reductions in iron burden over time; all pts had normal cardiac T2* levels at last follow-up and liver iron concentration (LIC) and serum ferritin were positively and strongly correlated at Months 24, 36, and 48 (Table). The subanalysis showed iron reduction in response to chelation and stabilization of iron markers after chelation was discontinued (Figure). Of the 15 pts who achieved TI in phase 1/2 studies, 10 (67%) restarted and then stopped iron chelation 25 (12-56) mo after beti-cel infusion; the 5 remaining pts continued on chelation. Of the 25 pts who achieved TI in phase 3 studies, 18 (72%) stopped iron chelation 29 (6-47) mo after beti-cel infusion; 11 (44%) pts never restarted and 7 (28%) restarted and then stopped again. Two pts in the subanalysis treated in a phase 1/2 study also received phlebotomy for approximately 20 and 56 mo post-infusion. Serious AEs occurring after 2 y in LTF-303 were reported in 8 pts (diabetic ketoacidosis, gonadotropic insufficiency, ectopic pregnancy, fetal death, cholelithiasis, gallbladder wall thickening/polyp, bacteremia with neutropenia, pulmonary embolism, and major depression; each n=1). No beti-cel-related AEs were observed beyond 2 y post-infusion. No deaths, replication-competent lentivirus, insertional oncogenesis, or malignancies were reported. Insertion site analysis indicated sustained polyclonal hematopoiesis. Conclusions: Beti-cel is a potentially curative gene therapy for pts with TDT through the ability to achieve TI with near-normal Hb levels. Sustained levels of HbA T87Q and effective restoration of iron homeostasis over time reduced iron management burden in pts treated with beti-cel. Figure 1 Figure 1. Disclosures Thompson: Baxalta: Research Funding; Biomarin: Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding; CRISPR Therapeutics: Research Funding; Vertex: Research Funding; Editas: Research Funding; Graphite Bio: Research Funding; Novartis: Research Funding; Agios: Consultancy; Beam: Consultancy; Global Blood Therapeutics: Current equity holder in publicly-traded company. Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau. Yannaki: Novartis: Speakers Bureau; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; SANDOZ: Speakers Bureau; Gilead: Speakers Bureau. Walters: Vertex pharmaceuticals: Consultancy; Ensoma, Inc.: Consultancy; BioLabs, Inc: Consultancy; AllCells, Inc: Consultancy. Porter: Agios: Consultancy, Honoraria; Protagonism: Honoraria; La Jolla Pharmaceuticals: Honoraria; Celgene (BMS): Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Silence Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Vifor: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kulozik: Sanofi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BioMedX: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Thrasher: Orchard Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; 4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees. Thuret: Novartis: Other: investigators for clinical trials, participation on scientific/medical advisory board; Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio, Inc.: Other: investigators for clinical trials, participation on scientific/medical advisory board; Celgene: Other: investigators for clinical trials, participation on scientific/medical advisory board. Lal: Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Insight Magnetics: Research Funding; Chiesi: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio, Inc.: Research Funding; Agios Pharmaceuticals: Consultancy; Terumo Corporations: Research Funding; Novartis: Research Funding; La Jolla Pharmaceutical Company: Research Funding. Cavazzana: Smart Immune: Other: co-founder. Rasko: Australian Government: Membership on an entity's Board of Directors or advisory committees; Cynata: Honoraria, Speakers Bureau; Genea: Current equity holder in publicly-traded company; Cure the Future Foundation: Membership on an entity's Board of Directors or advisory committees; Imago: Consultancy; Gene Technology Technical Advisory Board: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Speakers Bureau; NHMRC Mitochondrial Donation Expert Working Committee: Membership on an entity's Board of Directors or advisory committees; Australian Cancer Research: Membership on an entity's Board of Directors or advisory committees; FSHD Global Research Foundation: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Pfizer Inc: Honoraria, Speakers Bureau; Glaxo-Smith-Kline: Honoraria, Speakers Bureau; Spark: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; bluebird bio: Honoraria, Speakers Bureau. Du: bluebird bio, Inc.: Current Employment, Other: bluebird bio, Inc.: Employee, Ownership Interest and Salary. Colvin: bluebird bio, Inc.: Current Employment, Other: Employee, Ownership Interest and Salary. Kwiatkowski: Agios: Consultancy; Bioverativ: Research Funding; Imara: Consultancy, Research Funding; bluebird bio,Inc.: Consultancy, Research Funding; Sangamo: Research Funding; Silence Therapeutics: Consultancy; Bristol Myers Squibb: Consultancy; Apopharma: Research Funding; Celgene: Consultancy.

Introduction: Patients with transfusion-dependent β-thalassemia (TDT) have increased morbidity and mortality and reduced health-related quality of life (HRQoL) compared with the general population owing to the mental, physical, and time demands of chronic transfusions, iron chelation, and treatment. Betibeglogene autotemcel (beti-cel) is a one-time ex vivo gene therapy for TDT that enables stable production of functional adult hemoglobin (Hb) sufficient for transfusion independence (TI). In 2 ongoing, fully enrolled, phase 3 studies, HGB-207 (Northstar-2; NCT02906202) and HGB-212 (Northstar-3; NCT03207009), 32/36 (89%) evaluable patients achieved TI (weighted average Hb ≥9 g/dL without packed red blood cell transfusions for ≥12 mo after drug product infusion) with a median (min-max) weighted average Hb of 11.52 (9.3-13.7) g/dL during TI (as of March 9, 2021). In the current analysis, we evaluated the effect of beti-cel on HRQoL in 12 adults and 18 pediatric/adolescent patients with TDT enrolled in phase 3 studies who achieved TI. Methods: CD34+ cells were mobilized using granulocyte-colony stimulating factor and plerixafor, collected via apheresis, transduced with BB305 lentiviral vector, and infused back into patients after single-agent, pharmacokinetic-adjusted, busulfan-based myeloablation. HRQoL over time was assessed using the Pediatric Quality of Life Inventory (PedsQL; range, 0-100) for pediatric and adolescent patients ( Results: Forty-one patients were infused with beti-cel (HGB-207, n=23; HGB-212, n=18). Age at informed consent was 4-34 years; most patients (27/41, 66%) were Conclusions: Beti-cel is potentially curative in patients with TDT through the achievement of TI and near-normal Hb levels. Beti-cel addresses the disease pathophysiology at a genetic level and allows patients to achieve TI. Pediatric and adult patients with TDT who achieved TI after receiving beti-cel in phase 3 studies showed early and sustained improvements in HRQoL, despite relatively high HRQoL with supportive care at baseline. Figure 1 Figure 1. Disclosures Kwiatkowski: bluebird bio,Inc.: Consultancy, Research Funding; Celgene: Consultancy; Sangamo: Research Funding; Apopharma: Research Funding; Bristol Myers Squibb: Consultancy; Imara: Consultancy, Research Funding; Agios: Consultancy; Silence Therapeutics: Consultancy; Bioverativ: Research Funding. Locatelli: Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyl: Honoraria; bluebird bio, Inc.: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Walters: AllCells, Inc: Consultancy; BioLabs, Inc: Consultancy; Vertex pharmaceuticals: Consultancy; Ensoma, Inc.: Consultancy. Porter: Silence Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene (BMS): Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; La Jolla Pharmaceuticals: Honoraria; Protagonism: Honoraria; Vifor: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Honoraria. Yannaki: Gilead: Speakers Bureau; SANDOZ: Speakers Bureau; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Speakers Bureau. Kulozik: bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BioMedX: Consultancy, Honoraria. Thrasher: Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; 4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Thuret: bluebird bio, Inc.: Other: investigators for clinical trials, participation on scientific/medical advisory board; Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Other: investigators for clinical trials, participation on scientific/medical advisory board; Celgene: Other: investigators for clinical trials, participation on scientific/medical advisory board. Lal: Insight Magnetics: Research Funding; Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; La Jolla Pharmaceutical Company: Research Funding; Chiesi: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio, Inc.: Research Funding; Agios Pharmaceuticals: Consultancy; Terumo Corporations: Research Funding. Guo: bluebird bio, Inc.: Current Employment, Other: Employee, Ownership Interest and Salary. Colvin: bluebird bio, Inc.: Current Employment, Other: Employee, Ownership Interest and Salary. Gruppioni: bluebird bio, Inc.: Current Employment, Other: Employee, Ownership Interest and Salary. Thompson: Baxalta: Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; Biomarin: Research Funding; Celgene/BMS: Consultancy, Research Funding; CRISPR Therapeutics: Research Funding; Vertex: Research Funding; Editas: Research Funding; Graphite Bio: Research Funding; Novartis: Research Funding; Agios: Consultancy; Beam: Consultancy; Global Blood Therapeutics: Current equity holder in publicly-traded company.

Introduction: Hemoglobin (Hb) Agrinio (HBA2: c.89T>C (Leu29Pro) mutation) is a rare highly unstable Hb variant resulting from a leucine to proline substitution at codon29 of the alpha2-globin gene. Eleven homozygous cases of this non-deletional alpha thalassemia were described in literature. Clinical course ranged from moderate (non-transfusion dependent anemia) to severe (transfusion dependent thalassemia). In addition, one probable case of Hb barts hydrops fetalis was also reported in a Greek series. Hb Agrinio was first described in individuals of Greek or Cypriot origins. Subsequently, some cases were reported among patients living in Spain and Macedonia, most often of Gypsy origin. We report here the clinical presentation of the 8 homozygous cases diagnosed by molecular biology analysis in France and underline the severity of the antenatal phenotype of the disease. Methods: Cases were identified by contacting all the French laboratories involved in the molecular diagnosis of hereditary red blood cell (RBC) disorders. Three different families were retrieved, including 8 pediatric homozygous cases diagnosed by alpha globin gene sequencing between 2006 and 2020. Standardized clinical and laboratory data were obtained from treatment centers. All parents gave their written consent for molecular analysis and their authorization for participating in this study. Results: Consanguinity was present in all 3 families, however no obvious link was found between the 3. Two originated from Spain (1 of gypsy origin) and 1 from Bulgaria. All patients were homozygous for the HBA2: c.89T>C mutation, without any additional beta or alpha anomalies using gene sequencing and MLPA. Main clinical presentation findings of homozygous patients are reported in the table. Among the 8 cases, there was one in utero death at 22 weeks GA and 7 living births. Three patients, the more anemic at birth, died during the first hours of life with a clinical picture of hydrops fetalis for 2 of them. Despite a normal cerebral doppler at 32 weeks of GA, the third newborn (II2), presented at birth with a blueberry syndrome with cutaneous and hepatic extramedullary hematopoiesis, severe pulmonary arterial hypertension and Hb value of 6 g/dl, leading to neonatal death. Among the 4 survivor patients, one (III3), diagnosed in the antenatal period, benefited from in utero transfusions (TF) administered at 23 and 27 weeks because an accelerated middle cerebral artery peak systolic velocity of 52cm/s was measured. Hypospadias with ambiguous genitalia requiring surgical treatment was present in one patient and micropenis treated medically and undescended testis in a second one. All survivors (n=4/8) are currently under regular TF and chelation therapy. TF were generally (3/4) occasional in the first years of life and then became regular (>8 TF/year) later in childhood (at 6, 6, 7 years of age respectively). Conclusions: our national experience of homozygous Hb Agrinio cases revealed a more severe clinical course than reported in literature, with clinical presentation ranging from alpha-thalassemia major (Hb Barts hydrops fetalis) to severe non deletional HbH disease. Antenatal anemia was profound. In utero or neonatal deaths concerned half of the patients and additional ones were, even not biologically confirmed, also found in the family histories. Of note, congenital urogenital abnormalities similar to those found in the classical Hb Bart's Hydrops FetalisSyndrome were found in 2 patients. This up to now unreported severity could be explained by a closer monitoring and a more comprehensive clinical study of the cases/siblings allowing the antenatal period to be better described. The existence of aggravating genetic factor is another hypothesis and NGS analysis of genes involved in RBC disorders is planned. In couples at risk for homozygous Hb Agrinio, early genetic counseling and prenatal diagnosis should be offered. If the pregnancy is continued, a very close fetal ultrasound monitoring is mandatory and intrauterine TFs can be administered when severe fetal anemia is detected. Table Disclosures Thuret: Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Novartis pharma: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Introduction A phase 1/2 study of betibeglogene autotemcel (beti-cel; LentiGlobin for β-thalassemia) gene therapy in patients with transfusion-dependent β-thalassemia (TDT) demonstrated stable transgene expression with up to 4.5 years follow-up and enabled some patients to achieve transfusion independence. The interim results of two phase 3 studies, HGB-207 (NCT02906202; non-β0/β0 genotypes) and HGB-212 (NCT03207009; β0/β0, β0/β+ IVS-I-110 or β+ IVS-I-110/β+ IVS-I-110 genotypes), are presented here. Methods After G-CSF and plerixafor mobilization, autologous hematopoietic stem cells were collected via apheresis. Using a refined manufacturing process compared to the phase 1/2 study, CD34+ cells were transduced with BB305 lentiviral vector. Patients were infused with transduced cells following pharmacokinetic-adjusted, single-agent busulfan myeloablation. Target busulfan AUC was 3800–4500 (once daily) or 950–1125 (Q6H) μM*min. Statistics are shown as median (min–max). Results As of 13 Dec 2018 and 12 Apr 2019, 31 patients were treated in HGB-207 and HGB-212 with a follow-up of 8.1 (0.5–22.2) and 4.6 (1.5–15.7) months, respectively. Daily average busulfan AUC was 4450 (3709–9087) μM*min. Neutrophil and platelet engraftment were achieved at 25 (13–38) and 44 (20–84) days, respectively. Hospitalization from conditioning to discharge ranged from 30–92 days. In HGB-207, 10/11 patients followed for ≥6 months have stopped transfusions for ≥5.9 months (Figure 1). HbAT87Q levels at Months 6 (n=11), 12 (n=8) and 18 (n=3) were 9.5, 9.2, and 9.5 g/dL, respectively, which contributed to total hemoglobin (Hb) of 11.9, 12.4, and 11.3 g/dL at these time points, respectively. Marrow myeloid:erythroid ratios in 7/8 patients at Month 12 were 0.63–1.90 versus 0.14–0.48 at baseline, indicating improved erythropoiesis. In HGB-212, 3/4 patients followed for ≥6 months stopped transfusions for ≥6 months. Total Hb at last visit ranged from 10.5–13.6 g/dL and HbAT87Q was 9.5–12.6 g/dL at last assessment. Transfusion independence (weighted average Hb ≥9 g/dL without transfusions for ≥12 months) was achieved in 4/5 evaluable patients in HGB-207 and in the only evaluable patient in HGB-212. Post-infusion non-hematologic grade ≥3 adverse events (AEs) in ≥3 patients in either study were stomatitis (n=17), febrile neutropenia (n=11), pyrexia (n=4), epistaxis (n=3), and veno-occlusive liver disease (VOD; n=3). VOD prophylaxis with ursodiol or ursodiol/defibrotide was used in 24/31 patients. One beti-cel-related serious AE of thrombocytopenia was reported; platelet count was 63 × 109/L at last visit (Month 7). All patients remain alive. Summary Following treatment with beti-cel gene therapy, 10/11 and 3/4 patients with ≥6 months follow-up have stopped transfusions in HGB-207 and HGB-212, respectively. The safety profile of treatment with beti-cel is consistent with busulfan myeloablation.

This study&rsquo, s objective was to assess, on a national scale, residual risks of death, major disease-related events, and quality of care during the first five years in children diagnosed at birth with sickle cell disease (SCD). Data were retrospectively collected from medical files of all children with SCD born between 2006&ndash, 2010 in France. Out of 1792 eligible subjects, 1620 patients (71.8% SS or S/beta&deg, thalassemia -SB&deg, ) had available follow-up data, across 69 centers. Overall probability of survival by five years was 98.9%, with 12/18 deaths related to SCD. Probability of overt stroke by five years in SS/SB&deg, patients was 1.1%, while transcranial Doppler (TCD) was performed in 81% before three years of age. A total of 26 patients had meningitis/septicemia (pneumococcal in eight cases). Prophylactic penicillin was started at a median age of 2.2 months and 87% of children had received appropriate conjugate pneumococcal vaccination at one year. By five years, the probability of survival without SCD-related events was 10.7% for SS/SB&deg, patients. In contrast, hydroxyurea was prescribed in 13.7% and bone marrow transplant performed in nine patients only. In this study, residual risks of severe complications were low, probably resulting from a good national TCD, vaccination, and healthcare system coverage. Nonetheless, burden of disease remained high, stressing the need for disease-modifying or curative therapy.

International audience; We describe the clinical, hematologic and genetic characteristics of a retrospective series of 126 subjects from 64 families with hereditary xerocytosis. Twelve patients from six families carried a KCNN4 mutation, five had the recurrent p.Arg352His mutation and one had a new deletion at the exon 7-intron 7 junction. Forty-nine families carried a PIEZO1 mutation, which was a known recurrent mutation in only one-third of the cases and private sequence variation in others; 12 new probably pathogenic missense mutations were identified. The two dominant features leading to diagnosis were hemolysis that persisted after splenectomy and hyperferritinemia, with an inconstant correlation with liver iron content assessed by magnetic resonance imaging. PIEZO1-hereditary xerocytosis was characterized by compensated hemolysis in most cases, perinatal edema of heterogeneous severity in more than 20% of families and a major risk of post-splenectomy thrombotic events, including a high frequency of portal thrombosis. In KCNN4-related disease, the main symptoms were more severe anemia, hemolysis and iron overload, with no clear sign of red cell dehydration; therefore, this disorder would be better described as a ‘Gardos channelopathy’. These data on the largest series to date indicate that PIEZO1-hereditary xerocytosis and Gardos channelopathy are not the same disease although they share hemolysis, a high rate of iron overload and inefficient splenectomy. They demonstrate the high variability in clinical expression as well as genetic bases of PIEZO1-hereditary xerocytosis. These results will help to improve the diagnosis of hereditary xerocytosis and to provide recommendations on the clinical management in terms of splenectomy, iron overload and pregnancy follow-up.

IMPORTANCE: In children with sickle cell anemia (SCA), high transcranial Doppler (TCD) velocities are associated with stroke risk, which is reduced by chronic transfusion. Whether matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT) can reduce velocities in patients with SCA is unknown. OBJECTIVE: To determine the association of MSD-HSCT with TCD velocities as a surrogate for the occurrence of ischemic stroke in children with SCA. DESIGN, SETTING, AND PARTICIPANTS: Nonrandomized controlled intervention study conducted at 9 French centers. Patients with SCA were enrolled between December 2010 and June 2013, with 3-year follow-up ending in January 2017. Children with SCA were eligible if younger than 15 years, required chronic transfusions for persistently elevated TCD velocities, and had at least 1 sibling without SCA from the same 2 parents. Families agreed to HLA antigen typing and transplantation if a matched sibling donor was identified or to standard care in the absence of a matched sibling donor. EXPOSURES: MSD-HSCT (n = 32), compared with standard care (n = 35) (transfusions for ≥1 year with potential switch to hydroxyurea thereafter), using propensity score matching. MAIN OUTCOMES AND MEASURES: The primary outcome was the highest time-averaged mean of maximum velocities in 8 cerebral arteries, measured by TCD (TCD velocity) at 1 year. Twenty-five of 29 secondary outcomes were analyzed, including the highest TCD velocity at 3 years and normalization of velocities (

Several regimes of motion are evident in red blood cells (RBCs) under shear flow and are known to be controlled by the shear flow rate and by the deformability of the cell. Above a certain shear flow rate, healthy RBCs present a fluidized regime analogous to that of a droplet: the membrane adopts a tank-treading motion, i.e. rotates around the centre of mass of the cell, and its orientation oscillates around a mean value (Fig. 1). This motion is not observed in rigid RBCs which keep the same regime of motion as with low shear flow rate. The transition from one motion to the other depends on several intrinsic parameters including membrane viscosity, elasticity and cytoplasmic viscosity. Sickle cell disease (SCD) is a hereditary hemolytic anemia due to the presence of mutant hemoglobin, Hb S, which tends to polymerize in RBCs, reducing its deformability and resulting ultimately in RBC sickling. We postulate that SCD may affect RBCs capacity to adopt the tank-treading motion. Thanks to microfluidic chips coupled with high speed video, we studied the fraction of RBCs displaying a tank-treading motion (% of TT) at moderate shear stresses (0.4-0.6 Pa), in homozygous SCD patients (n=30) and in normal subjects (n=12). At the time of sampling, SCD patients were in steady state (no vaso-occlusive crisis or other acute complications) and not transfused for at least 3 months. Around 3 microL of total blood were necessary for each measurement. RBCs were studied under atmospheric conditions and exhibited the normal discoid shape. We showed first that the % of TT is significantly different in SCD patients compared to controls, with no overlap between the values of each groups (respectively 70.4±12.9% versus 98.6±0.9%). Second, measurements performed on different cells fractions isolated by cell density or in the presence of different NaCl concentrations, showed that the % of TT cells is sensitive to cell density and hydration status, both in normal subjects and in SCD patients. Finally, we evaluate the % of TT in RBC samples drawn just before or during 10 episodes of vaso-occlusive crisis from 8 different patients. The definition of a vaso-occlusive crisis, for this specific study, was set as an episode with pain in at least 2 different locations requiring hospitalization at least for 24h. The results revealed that, for a given patient, the % of TT cells varies significantly for 12h before as well as during vaso-occlusive crises with kinetics comparable from one patient to another. In conclusion, we described here a new inexpensive biological test able to discriminate healthy RBCs from sickle RBCs, with preliminary results suggesting potential interest for monitoring the clinical status of SCD patients. Further analysis will be necessary to determine if this parameter is suitable for predicting the occurrence of vaso-occlusive crises early enough to allow preventive actions. Fig1: Schematic view of the regime of motion corresponding to tank-treading. Flow direction is from left to right and RBCs are observed from the direction of the shear gradient. The black dot on the RBCs displays the motion of a membrane element on the RBC surface. The axis of symmetry remains in the shear plane, the body of the RBC oscillates slightly as the membrane rotates around it Disclosures Thuret: Addmedica: Research Funding; bluebird bio: Research Funding; Novartis: Research Funding.

International audience; In this retrospective study, we evaluate long-term complications in nearly all β-thalassemia-major patients who successfully received allogeneic hematopoietic stem cell transplantation in France. Ninety-nine patients were analyzed with a median age of 5.9 years at transplantation. The median duration of clinical follow up was 12 years. All conditioning regimens were myeloablative, most were based on busulfan combined with cyclophosphamide, and more than 90% of patients underwent a transplant from a matched sibling donor. After transplantation, 11% of patients developed thyroid dysfunction, 5% diabetes, and 2% heart failure. Hypogonadism was present in 56% of females and 14% of males. Female patients who went on to normal puberty after transplant were significantly younger at transplantation than those who experienced delayed puberty (median age 2.5 vs. 8.7 years). Fertility was preserved in 9 of 27 females aged 20 years or older and 2 other patients became pregnant following oocyte donation. In addition to patient’s age and higher serum ferritin levels at transplantation, time elapsed since transplant was significantly associated with decreased height growth in multivariate analysis. Weight growth increased after transplantation particularly in females, 36% of adults being overweight at last evaluation. A comprehensive long-term monitoring, especially of endocrine late effects, is required after hematopoietic stem cell transplantation for thalassemia.

Clinical and hematologic characteristics of beta(β)-thalassemia are determined by several factors resulting in a wide spectrum of severity. Phenotype modulators are: HBB mutations, HBA defects and fetal hemoglobin production modulators (HBG2:g.-158C>T polymorphism, HBS1L-MYB intergenic region and the BCL11A). We characterized 54 genetic variants at these five loci robustly associated with the amelioration of beta-thalassemia phenotype, to build a predictive score of severity using a representative cohort of 890 β-thalassemic patients. Using Cox proportional hazard analysis on a training set, we assessed the effect of these loci on the age at which patient started regular transfusions, built a Thalassemia Severity Score, and validated it on a testing set. Discriminatory power of the model was high (C-index=0.705; R(2)=0.343) and the validation conducted on the testing set confirmed its predictive accuracy with transfusion-free survival probability (P, peer-reviewed

Mutations in genes encoding proteins that are involved in mitochondrial heme synthesis, iron-sulfur cluster biogenesis, and mitochondrial protein synthesis have previously been implicated in the pathogenesis of the congenital sideroblastic anemias (CSAs). We recently described a syndromic form of CSA associated with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD). Here we demonstrate that SIFD is caused by biallelic mutations in TRNT1, the gene encoding the CCA-adding enzyme essential for maturation of both nuclear and mitochondrial transfer RNAs. Using budding yeast lacking the TRNT1 homolog, CCA1, we confirm that the patient-associated TRNT1 mutations result in partial loss of function of TRNT1 and lead to metabolic defects in both the mitochondria and cytosol, which can account for the phenotypic pleiotropy.

The presence of cerebral macrovasculopathy as detected by transcranial Doppler (TCD) exposes children with sickle cell anemia (SCA) to a high risk of stroke, preventable by chronic transfusion or stem cell transplantation (SCT). However, long-term outcomes of stenosis have not been well described. The Drepagreffe trial (NCT01340404) was a prospective trial comparing cerebral vasculopathy outcome after SCT vs standard-care in children with abnormal TCD with or without stroke history. Results from the whole population have recently been reported (Bernaudin et al, JAMA 2019). The decrease in velocities was significantly higher after SCT than standard-care (p Sixty-seven SCA-children on chronic transfusion for abnormal-TCD history were enrolled (Dec-2010/June-2013) in this prospective trial with two treatment groups defined by the random-availability of having a matched-sibling donor (MSD). Thirty-two with MSD were transplanted while 35 without MSD were maintained on chronic transfusion for at least one-year and eventually switched to hydroxyurea thereafter if no stenosis and normalized velocities. Cerebral and cervical magnetic-resonance angiography (MRA) was systematically performed at enrollment, and 1- and 3-year post-enrollment. Stenosis was defined as a narrowing ≥25%. The MRA stenosis-score, was calculated as the weighted sum of the scores in the 8 assessed cerebral arteries (right and left middle cerebral (MCA), anterior (ACA), internal carotid (ICA) and extracranial internal carotid arteries (eICA)), with 0 = stenosis, 1 = mild stenosis (25-49%), 2 = moderate stenosis (50-74%), 3 = severe stenosis (75-99%), and 4 = occlusion. All 67 patients were alive at 3-year, and the 32 transplanted patients successfully engrafted. No stroke or recurrence occurred during the follow-up. No chronic-GVHD was observed. Among the 7 patients with stroke-history, all had stenosis at enrollment and the stenosis score increased in the 4 transplanted patients, but always in the arteries with previous stenosis and those feeding ischemic territories, while stenosis score remained mostly stable in the 3 patients maintained on chronic transfusion,. However, the difference between treatment groups was not significant (p=0.057). Among the 60 stroke-free patients at enrollment, 28 with MSD were transplanted while 32 without MSD were maintained on chronic transfusion. At enrollment, 28 patients (14 patients in each treatment group) had stenosis. At 1-year, 9 patients in the SCT group had stenosis, whereas in the transfusion/standard-care group, 10 had stenosis. At 3-year, 5 patients in the SCT group had stenosis, while 10 still had stenosis in the standard-care group. Moreover, 2 patients, who had no stenosis at enrollment, developed one stenosis between 1 and 3-year, despite chronic transfusion in one case and after switch to hydroxyurea in the other. In another patient, stenosis had disappeared on chronic transfusion at 1-year, although it reappeared at 3-year after a switch to hydroxyurea. In the SCT group, no worsening of stenosis was observed, and stenosis improved in 13/14 and was stable in one; in contrast, worsening of stenosis score was observed in the standard-care group in 6 patients on chronic transfusion (p=0.035), The stenosis-score between enrollment and 3-year improved more significantly in the SCT group (mean (SD): -1.39 (2.47)) than in the standard care group (-0.06 (1.18)); (p=0.012). Conclusions: This prospective trial reporting the outcome of stenosis in stroke and stroke-free SCA-patients with a history of abnormal-TCD shows a trend to worsening of the stenosis-score after SCT in stroke-patients, but no stroke recurrence; in contrast, in stroke-free patients, stenosis outcome was significantly better after SCT and with better prevention of stenosis occurrence than on standard care. These results support early recommendation of SCT in children with a history of abnormal-TCD and an MSD. Figure Disclosures Verlhac: Addmedica, Paris: Other: Financial Support; Bluebird Bio: Consultancy. Brousse:bluebird bio: Consultancy; Add medica: Consultancy. De Montalembert:Addmedica: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees. Thuret:BlueBird bio: Other: investigators for clinical trials, participation on scientific/medical advisory board; Celgene: Other: investigators for clinical trials, participation on scientific/medical advisory board; Novartis: Other: investigators for clinical trials, participation on scientific/medical advisory board; Apopharma: Consultancy. Bernaudin:GBT: Membership on an entity's Board of Directors or advisory committees; AddMedica: Honoraria, Other: Help for travel to meeting; BlueBirdBio: Consultancy.

Background: The goals of newborn screening programs (NBS) for sickle cell disease (SCD) are to reduce early mortality and morbidity, by introducing preventive measures like penicillin prophylaxis, pneumococcal vaccines and Transcranial Doppler (TCD) screening. The main objective of this study (NCT 03119922) was to assess on a national scale and during the first 5 years residual risks of death, overt stroke and bacterial meningitis/septicemia resulting from current TCD and pneumococcal prophylactic utilization in SCD children diagnosed at birth. An additional objective was to determine the frequency of other main SCD-related events and the use of disease-modifying or curative therapy. Methods: Using the national NBS database between 2006-2010, data was collected in 2014/2015 from the patients' medical files up to the age of 5 years, and included age at first prescription of penicillin, occurrence of death/overt stroke/bacterial meningitis and septicemia, age at first transfusion (TF), use of pneumococcal vaccines/chronic transfusion program/hydroxyurea (HU)/hematopoietic stem cell transplantation (HSCT) and TCD results. Results: Out of 1792 eligible subjects, 152 (8%) were lost to follow-up. A total of 1620 patients with available follow-up data across 69 centers constituted the EVADREP cohort. Of them, 71.8% had SS or S beta°-thalassemia (SB°) while 20.3% had SC /S Beta+-thalassemia (SB+) disease, and 59.6% resided in Paris area. Overall mortality rate for all patients was 0.23/100 person-years during the 5 first years of life and probability of survival at 5 years was 98.9% (95%CI: 98.2-99.3), with 18 deaths during the study period, 12 related to SCD (11 patients SS or SB°). The probability of overt stroke at 5 years was 1.1% all in SS/SB° patients. DTC was performed in 56% and 81% of patients before 2 and 3 years of age, respectively. The probability of abnormal TCD at 5 years was 10.4%. A total of 26 patients had a severe infection (meningitis or septicemia), lethal in 8 cases and caused by a pneumococcal strain in 8 cases. More than 99% of patients were prescribed prophylactic penicillin, started at a median age of 2.2 months of life. Full pneumococcal vaccination (at least 4 PCV and one P23) was performed in only 47.4% before 3 years but the probability of receiving P23 was 90% at 5 years. At 3 years, 42.9% of the EVADREP cohort had experienced a first VOE and the probability of survival without VOE was 62.4% [60.0-64.8] at 5 years. When pooling all SCD-related events (death, stroke, severe infection, VOE, acute anemia, as well as abnormal DTC, pneumonia and/or ACS and transfusion), 58.6% of children had experienced at least one event at 3 years. The probability of survival without SCD-related events at 5 years was 10.7% [0.9-12.6] for SS/SB° patients and 46.3% (41.5-51) for SC/SB+. In sharp contrast, HU was prescribed in 13.7% and HSCT performed in 9 patients only. Vaccination and DTC coverage, use of TF program and HU were significantly higher in larger centers. Summary/Conclusion: Current residual risks of severe complications and mortality rates on a national scale are similar to those observed in SCD expert center cohorts, presumably as a result of good TCD and vaccination coverage and an easy access to health care in France. Further improvement could be achieved with better referral to centers of expertise. The burden of disease is still high and increased use of disease modifying or curative therapy should benefit more children in the future. Disclosures Brousse: Add medica: Consultancy; bluebird bio: Consultancy. Bernaudin:BlueBirdBio: Consultancy; AddMedica: Honoraria, Other: Help for travel; GBT: Membership on an entity's Board of Directors or advisory committees. de Montalembert:AddMedica: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; bluebird bio, Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background Transfusion-dependent β-thalassemia (TDT) is a severe genetic disease caused by impaired β-globin production leading to severe anemia and lifelong transfusion dependence. Autologous CD34+ cells encoding a βA-T87Q-globin gene (LentiGlobin for β-thalassemia) is currently being evaluated in patients with TDT. In the phase 1/2 Northstar study, 3/8 patients with β0/β0 genotypes became transfusion independent. The drug product (DP) manufacturing process (CD34+ cell transduction) was then refined to improve clinical outcomes. Interim results are presented here from the ongoing, international, single-arm, phase 3 Northstar-3 study (HGB-212; NCT03207009) evaluating LentiGlobin gene therapy in patients ≤50 years of age with TDT and either β0 or β+ IVS-I-110 mutations on both HBB alleles. Methods Patients with TDT undergo hematopoietic stem cell mobilization with G-CSF and plerixafor. CD34+ cells collected via apheresis are transduced with BB305 lentiviral vector. Patients undergo myeloablative, single-agent, pharmacokinetic-adjusted busulfan conditioning over 4 days and are infused with transduced cells. The primary efficacy endpoint is transfusion reduction (≥60% reduction in transfused red blood cell (RBC) volume post-DP infusion compared with pre-DP infusion). A key secondary endpoint is transfusion independence (TI; weighted average hemoglobin [Hb] ≥9 g/dL without RBC transfusions for ≥12 months). Patients are followed for 2 years and offered participation in a long-term follow-up study. Summary statistics presented as median (min - max). Results As of 12 April 2019, 11 patients (7 β0/β0, 2 β0/IVS-I-110, 2 homozygous IVS-I-110genotypes) were treated with LentiGlobin and have a median follow-up of 4.6 (1.5 - 15.7) months. Median age at enrollment was 17 (7 - 33) years; 3 patients were Median time to neutrophil and platelet engraftment was 26 (14 - 38) days and 36 (25 - 64) days, respectively; 3 patients with 1 - 3 months follow-up had not yet achieved platelet engraftment. There was one grade 3 bleeding adverse event (AE) of epistaxis from DP infusion to platelet engraftment, but no grade ≥ 3 bleeding AEs after platelet engraftment. Non-hematologic grade ≥3 AEs in ≥2 patients after DP infusion were febrile neutropenia, stomatitis, and pharyngeal inflammation. AEs considered possibly related to LentiGlobin were abdominal pain (n=2) and leukopenia and thrombocytopenia in one patient. Serious AEs after DP infusion were pyrexia (n=2), and one event each of febrile neutropenia, headache, neutropenia, stomatitis, thrombocytopenia, and congestive heart failure. Congestive heart failure occurred in a patient (screening cardiac T2* 16.6 msec) who had a fall in left ventricular ejection fraction associated with worsening of cardiac iron pre-engraftment. Three of 4 patients followed for ≥ 6 months have stopped transfusions for ≥ 6 months with total Hb of 10.5 - 13.6 g/dL at last visit. Gene therapy-derived HbAT87Q stabilized approximately 6 months after infusion and was 9.5 - 12.6 g/dL at last assessment. The fourth patient with ≥ 6 months follow-up had a Hb of 8.6 g/dL at last visit after being off transfusions for 2.8 months; however, has since received additional transfusions due to symptomatic anemia. The only patient with ≥12 months follow-up (β0/β0 genotype) achieved transfusion independence. Of the 5 patients with ≥3 to Summary Interim results from Northstar-3 indicate that refinements in the manufacturing of LentiGlobin gene therapy led to higher DP VCN and proportion of transduced cells. In patients with TDT and either a β0 or IVS-I-110 mutation at both alleles of the HBB gene, 3/4 with ≥ 6 months have stopped transfusions and one patient has achieved the protocol definition of transfusion independence. The safety profile of LentiGlobin gene therapy was generally consistent with myeloablative busulfan conditioning. Disclosures Lal: Terumo Corporation: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Insight Magnetics: Research Funding; Protagonist Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio: Research Funding; Novartis: Research Funding; La Jolla Pharmaceutical Company: Research Funding. Locatelli:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kwiatkowski:Terumo: Research Funding; Novartis: Research Funding; Imara: Consultancy; Apopharma: Research Funding. Kulozik:Bluebird Bio: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Porter:Celgene: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Protagonism: Honoraria; La Jolla: Honoraria; Vifor: Honoraria; Silence therapeutics: Honoraria; Bluebird bio: Consultancy, Honoraria. Thuret:Celgene: Other: investigators for clinical trials, participation on scientific/medical advisory board; Novartis: Other: investigators for clinical trials, participation on scientific/medical advisory board; Apopharma: Consultancy; BlueBird bio: Other: investigators for clinical trials, participation on scientific/medical advisory board. Elliot:bluebird bio, Inc.: Employment, Equity Ownership. Chen:bluebird bio, Inc.: Consultancy. Colvin:bluebird bio, Inc.: Employment, Equity Ownership. Thompson:bluebird bio, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Baxalta: Research Funding.

Background Transfusion-dependent β-thalassemia (TDT) is treated with regular, lifelong red blood cell (RBC) transfusions and despite iron-chelating therapy, carries a risk of serious organ damage from iron overload and other complications. Transplantation with autologous CD34+ cells encoding a βA-T87Q-globin gene (LentiGlobin for β-thalassemia) is being evaluated in patients with TDT. Interim results are presented here from the ongoing, international, single-arm, phase 3 Northstar-2 study (HGB-207; NCT02906202) of LentiGlobin gene therapy in pediatric, adolescent, and adult patients with TDT (defined by receiving ≥100 mL/kg/yr of RBCs or ≥8 RBC transfusions/yr) and non-β0/β0 genotypes. Methods Patients undergo hematopoietic stem cell (HSC) mobilization with G-CSF and plerixafor. Following apheresis, CD34+ cells are transduced with BB305 lentiviral vector and infused into patients after pharmacokinetic-adjusted, single-agent busulfan myeloablation. The primary efficacy endpoint is transfusion independence (TI; weighted average hemoglobin [Hb] ≥9 g/dL without RBC transfusions for ≥12 months). HSC engraftment, βA-T87Q-globin expression, Hb levels, detection of replication competent lentivirus (RCL), and adverse events (AE) are also assessed. Patients are followed for 2 years and offered participation in a long-term follow-up study. Summary statistics are presented as median (min - max). Results Twenty patients were treated in Northstar-2 as of 13 December 2018 and have been followed for a median of 8.1 (0.5 - 22.2) months. At enrollment, median age was 16 (8 - 34) years; 5 patients were Non-hematologic grade ≥3 AEs in ≥3 patients after LentiGlobin infusion included stomatitis (n=12), febrile neutropenia (n=6), pyrexia (n=4), epistaxis (n=3), and veno-occlusive liver disease (n=3). One serious AE of grade 3 thrombocytopenia was considered possibly related to LentiGlobin. No patient died, had graft failure, or had detection of RCL. No insertional oncogenesis has been observed. Gene therapy-derived HbAT87Q stabilized approximately 6 months after infusion. In adolescent and adult patients treated with LentiGlobin, median HbAT87Q at Months 6, 12 and 18 was 9.5 (n=11), 9.2 (n=8), and 9.5 (n=3) g/dL, respectively. The median total Hb without transfusions at Months 6, 12, and 18 were 11.9 (n=11), 12.4 (n=8), 12.3 (n=2) g/dL, respectively. At Month 6, 91% (10/11) of patients had total Hb of >11 g/dL without transfusions. Five adolescent and adult patients were evaluable for the primary endpoint of transfusion independence, 4 (80%) of whom achieved TI. The median weighted average Hb during TI was 12.4 (11.5 - 12.6) g/dL which compared favorably to pre-transfusion nadir Hb levels before enrollment (median 9.1 g/dL [7.5 - 10.0 g/dL]). At time of analysis, the median duration of TI was 13.6 (12.0 - 18.2) months. One patient who did not achieve TI stopped transfusions for 11.4 months but resumed transfusions due to recurrent anemia. This patient had a 71.4% reduction in RBC transfusion volume from Month 6 to Month 18 compared to baseline. Marrow cellularity and myeloid:erythroid (M:E) ratios were evaluated in 8 adolescent and adult patients with ≥12 months follow-up to assess the effect of LentiGlobin treatment on dyserythropoiesis. Seven of 8 patients had improved marrow M:E ratios at Month 12 (0.63 - 1.90) compared with baseline (0.14 - 0.48). In patients who stopped transfusions, soluble transferrin receptor levels were reduced by a median of 72% (58% - 78%) at Month 12 (n=6). Updated outcomes in adolescents and adults and outcomes in pediatric patients will be reported. Summary In this update of the Northstar-2 study of LentiGlobin gene therapy in patients with TDT and non-β0/β0 genotypes, transfusion independence was observed in 4/5 evaluable adolescent and adults and 10/11 treated patients had total Hb of >11 g/dL without transfusion support 6 months after LentiGlobin infusion. HbAT87Q stabilized approximately 6 months after treatment and patients who stopped RBC transfusions had improved erythropoiesis. A safety profile consistent with busulfan conditioning was observed after LentiGlobin gene therapy. Disclosures Thompson: bluebird bio, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Baxalta: Research Funding. Walters:TruCode: Consultancy; AllCells, Inc: Consultancy; Editas Medicine: Consultancy. Kwiatkowski:bluebird bio, Inc.: Consultancy, Research Funding; Terumo: Research Funding; Celgene: Consultancy; Agios: Consultancy; Imara: Consultancy; Apopharma: Research Funding; Novartis: Research Funding. Porter:Protagonism: Honoraria; Celgene: Consultancy, Honoraria; Bluebird bio: Consultancy, Honoraria; Agios: Consultancy, Honoraria; La Jolla: Honoraria; Vifor: Honoraria; Silence therapeutics: Honoraria. Thrasher:Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Generation Bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; 4BIOCapital: Membership on an entity's Board of Directors or advisory committees. Thuret:BlueBird bio: Other: investigators for clinical trials, participation on scientific/medical advisory board; Celgene: Other: investigators for clinical trials, participation on scientific/medical advisory board; Novartis: Other: investigators for clinical trials, participation on scientific/medical advisory board; Apopharma: Consultancy. Elliot:bluebird bio, Inc.: Employment, Equity Ownership. Tao:bluebird bio, Inc.: Employment, Equity Ownership. Colvin:bluebird bio, Inc.: Employment, Equity Ownership. Locatelli:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Miltenyi: Honoraria.

Congenital sideroblastic anemias (CSAs) are a heterogeneous group of inherited disorders identified by pathological erythroid precursors with perinuclear mitochondrial iron deposition in bone marrow. An international collaborative group of physicians and laboratory scientists collated clinical information on cases of CSA lacking known causative mutations, identifying a clinical subgroup of CSA associated with B immunodeficiency, periodic fevers, and development delay. Twelve cases from 10 families were identified. Median age at presentation was 2 months. Anemia at diagnosis was sideroblastic, typically severe (median hemoglobin, 7.1 g/dL) and markedly microcytic (median mean corpuscular volume, 62.0 fL). Clinical course involved recurrent febrile illness and gastrointestinal disturbance, lacking an infective cause. Investigation revealed B-cell lymphopenia (CD19⁺ range, 0.016-0.22 × 10⁹/L) and panhypogammaglobulinemia in most cases. Children displayed developmental delay alongside variable neurodegeneration, seizures, cerebellar abnormalities, sensorineural deafness, and other multisystem features. Most required regular blood transfusion, iron chelation, and intravenous immunoglobulin replacement. Median survival was 48 months, with 7 deaths caused by cardiac or multiorgan failure. One child underwent bone marrow transplantation aged 9 months, with apparent cure of the hematologic and immunologic manifestations. We describe and define a novel CSA and B-cell immunodeficiency syndrome with additional features resembling a mitochondrial cytopathy. The molecular etiology is under investigation.

PubMed ID: 23812939, Accumulation of myocardial iron is the cause of heart failure and early death in most transfused thalassemia major patients. T2* cardiovascular magnetic resonance provides calibrated, reproducible measurements of myocardial iron. However, there are few data regarding myocardial iron loading and its relation to outcome across the world. A survey is reported of 3,095 patients in 27 worldwide centers using T2* cardiovascular magnetic resonance. Data on baseline T2* and numbers of patients with symptoms of heart failure at first scan (defined as symptoms and signs of heart failure with objective evidence of left ventricular dysfunction) were requested together with more detailed information about patients who subsequently developed heart failure or died. At first scan, 20.6% had severe myocardial iron (T2*?10ms), 22.8% had moderate myocardial iron (T2* 10-20ms) and 56.6% of patients had no iron loading (T2*>20ms). There was significant geographical variation in myocardial iron loading (24.8-52.6%; P

Although hematopoietic stem cell transplantation (HSCT) offers curative potential for beta-thalassemia major (beta-TM), it is associated with a variable but significant incidence of graft rejection. We studied the French national experience for improvement over time and the potential benefit of antithymocyte globulin (ATG). Between December 1985 and December 2007, 108 patients with beta-TM underwent HSCT in 21 different French transplantation centers. The majority of patients received a matched sibling transplant (n = 96) and a busulfan- and cyclophosphamide-based conditioning regimen (n = 95), also with ATG in 57 cases. Ninety-five of the 108 patients survived, with a median follow-up of 12 years. Probabilities of 15-year survival and thalassemia-free survival after first HSCT were 86.8% and 69.4%, respectively. Graft failure occurred in 24 patients, 11 of whom underwent a second HSCT. The use of ATG was associated with a decrease in rejection rate from 35% to 10%. Thalassemia-free survival improved significantly with time, reaching 83% in the 54 patients undergoing HSCT after 1994 (median time of HSCT). In view of the increased risk of graft rejection after matched sibling HSCT, current French national guidelines recommend, for all children at risk for beta-TM, the systematic addition of ATG to the myeloablative conditioning regimen and special attention to optimize transfusion and chelation therapy in the pretransplantation period.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Lopinavir/ritonavir pharmacokinetics have been fully investigated in adults and children. WHAT THIS STUDY ADDS • Lopinavir/ritonavir population pharmacokinetics in 96 neonates and infants from birth to less than 2 years (1.16 to 10.4 kg) showed that CL/F and V/F were dependent on body weight on an allometric basis and post-menstrual age. AIMS Because of immature hepatic metabolism, lopinavir could present specific pharmacokinetics in the first weeks of life. We aimed at determining the optimal dosing regimen in neonates and infants weighing 1 to 10.5 kg. METHODS Lopinavir/ritonavir (LPV/r) pharmacokinetics were studied in 96 infants using a population approach. RESULTS A one-compartment model described LPV/r pharmacokinetics. Normalized to a 70 kg adult using allometry, clearance (CL/F) and distribution volume (V/F) estimates were 5.87 l h−1 70 kg−1 and 91.7 l 70 kg−1. The relative bioavailabilty, F, increased with post-menstrual age (PMA) and reached 50% of the adult value at 39.7 weeks. CONCLUSIONS Size and PMA explained some CL/F and V/F variability in neonates/infants. Based upon trough concentration limitations, suggested LPV/r dosing regimens were 40 mg 12 h−1, 80 mg 12 h−1 and 120 mg 12 h−1 in the 1–2 kg, 2–6 kg and 6–10 kg group, respectively.

Background Transfusion-dependent β-thalassemia (TDT) is a severe genetic disease caused by impaired β-globin production, leading to severe anemia, lifelong transfusion dependence with iron overload and serious comorbidities. Gene therapy (GT) offers a potentially transformative option for these patients. LentiGlobin GT contains autologous CD34+ hematopoietic stem cells (HSCs) transduced ex vivo with the BB305 lentiviral vector (LVV) encoding β-globin with a T87Q substitution. The safety and efficacy of LentiGlobin in patients with TDT was assessed in the phase 1/2 Northstar study in which 8/10 patients with non-β0/β0 genotypes and 3/8 patients with a β0/β0 genotype stopped transfusions. A refined manufacturing process to improve drug product (DP) characteristics is being evaluated in the studies presented here. Methods Northstar-2 (HGB-207; NCT02906202) and Northstar-3 (HGB-212; NCT03207009) are ongoing, international, single-arm, phase 3 studies in patients with TDT (≥ 100 mL/kg/yr of red blood cells [RBCs] or ≥ 8 RBC transfusions/yr) and non-β0/β0 genotypes or a β0/β0 genotype, respectively. HSCs were collected by apheresis after G-CSF and plerixafor mobilization. CD34+ HSCs were transduced with the BB305 LVV using a refined manufacturing process. Patients received single-agent, myeloablative busulfan conditioning and transduced cells were infused. The primary endpoint in Northstar-2 is the proportion of patients achieving transfusion independence (TI, weighted average hemoglobin [Hb] ≥ 9g/dL without RBC transfusions for ≥ 12 months continuously) and in Northstar-3 is the proportion of patients achieving transfusion reduction (≥ 60% reduction in transfused RBC volume post-DP infusion compared to pre-DP infusion). Patients were evaluated for engraftment, DP and peripheral blood vector copy number (VCN), GT-derived Hb (HbAT87Q), adverse events (AEs), vector integration, and evidence of replication competent lentivirus (RCL). Patients are followed for 2 years and offered participation in a long-term follow-up study. Results Eleven patients (median age 20 [min - max: 12 - 24] years) with TDT and non-β0/β0 genotypes (5 β+/β0, 4 βE/β0, 2 β+/β+) have been treated in Northstar-2 as of May 15, 2018 with a median follow-up of 8.5 (min - max: 0.3 - 16.2) months. DPs had a median cell dose of 7.4 x 106 (min - max: 5.0 - 19.4 x 106) CD34+ cells/kg, median VCN of 3.4 (min - max: 2.4 - 5.6) copies/diploid genome (c/dg) and a median of 82% (min - max: 53 - 90%) CD34+ cells were transduced. Median time to neutrophil and platelet engraftment was 21.5 (min - max: 16 - 28) and 44.5 (min - max: 34 - 84) days, respectively, in 10 patients; 1 patient was not yet evaluable. Serious AEs after DP infusion included 2 events of grade 4 liver veno-occlusive disease treated with defibrotide and 1 event each of hypotension, hypoxia, sepsis, and transfusion reaction, all resolved. Only 1 AE (grade 1 abdominal pain) was related to LentiGlobin. There were no deaths or graft failure and no evidence of vector-mediated RCL or clonal dominance. Of 8 patients with ≥ 6 months follow-up, 7 have stopped RBC transfusions. At last study visit, peripheral blood VCN was 1.1 - 5.0 c/dg and total Hb was 11.1 - 13.3 g/dL of which 7.6 - 10.2 g/dL (68 - 92%) was contributed by HbAT87Q. Median Hb at month 6 was 11.9 (min - max: 11.2 - 13.3) g/dL. The first treated patient achieved TI. The additional patient with ≥ 6 months follow-up had no transfusions for 11 months, however had a peripheral blood VCN of 0.2 c/dg and resumed transfusions due to symptomatic anemia. Bone marrow assessment of dyserythropoesis and data with longer follow-up will be presented. Two patients, 26- and 7- years old, have been treated in Northstar-3. Both had 2 DP lots manufactured with DP VCNs of 2.9/3.3 and 3.4/3.9 c/dg and 82%/85% and 78%/78% CD34+ cells were transduced, respectively. Both successfully engrafted. Additional data for these patients will be presented. Summary Seven of 8 patients with TDT and non-β0/β0 genotypes produced sufficient HbAT87Q to stop chronic transfusions following LentiGlobin GT in Northstar-2. The safety profile appears consistent with busulfan myeloablative conditioning with no grade ≥ 3 DP-related AEs. Initial results show DP characteristics in Northstar-3 are consistent with those in Northstar-2. Additional data from Northstar-3 will determine the impact of HbAT87Q production on transfusion reduction in patients without endogenous β-globin production. Disclosures Locatelli: bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Walters:AllCells Inc.: Other: Medical Director; ViaCord Processing Lab: Other: Medical Director; bluebird bio: Research Funding; Sangamo Therapeutics: Consultancy. Kwiatkowski:Terumo: Research Funding; Apopharma: Research Funding; Novartis: Research Funding; Agios Pharmaceuticals: Consultancy, Research Funding; bluebird bio: Consultancy, Honoraria, Research Funding. Porter:Agios: Honoraria; Cerus: Honoraria; Novartis: Consultancy. Thuret:Addmedica: Research Funding; bluebird bio: Research Funding; Novartis: Research Funding. Kulozik:bluebird bio: Consultancy, Honoraria. Lal:Terumo Corporation: Research Funding; Celgene Corporation: Research Funding; Insight Magnetics: Research Funding; Bluebird Bio: Research Funding; La Jolla Pharmaceutical Company: Consultancy, Research Funding; Novartis: Research Funding. Thrasher:Orchard Therapeutics: Consultancy, Equity Ownership; Generation Bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Elliot:bluebird bio: Employment, Equity Ownership. Tao:bluebird bio: Employment, Equity Ownership. Asmal:bluebird bio: Employment, Equity Ownership. Thompson:Amgen: Research Funding; Baxalta/Shire: Research Funding; La Jolla Pharmaceutical: Research Funding; Novartis: Research Funding; bluebird bio: Consultancy, Research Funding; Celgene: Research Funding; Biomarin: Research Funding.

Hydroxyurea (HU) is approved in EU and USA for preventing vaso-occlusive crises (VOC) including acute chest syndromes (ACS) in adults, adolescents and children ≥2 years with sickle-cell disease (SCD). Further to the double blinded, randomized controlled Multicenter Study of Hydroxyurea administration (MSH) which provided the first data on clinical efficacy of HU (Charache 1995), a few follow-up studies suggested that long-term use of HU resulted in significant clinical benefit on patient outcome. This was reflected by lower mortality rates in HU-treated patients compared to conventionally treated patients (Steinberg 2003 & 2010, Voskaridou 2010, Lê 2015). Sustained hematological and clinical response after several years of follow-up at maximal tolerated dose was further shown in subsequent studies, especially the LaSHS study (Voskaridou 2010). Based on these data, the ESCORT-HU (European Sickle Cell Disease COhoRT - HydroxyUrea) study was launched aiming in the establishment of the safety and the sustainability of hematological and clinical benefits to HU administration in the prevention of sickle-cell vaso-occlusive crises in routine practice. We hereby present preliminary results from a large cohort of patients enrolled in the study between January 2009 and June 2017. 1920 patients were enrolled from 63 centers in France, Germany, Greece and Italy, For 147 of the 600 HU-naive patients (never treated with HU before enrolment) and started on HU for VOC or ACS, there was documented clinical outcome (number of VOC >48h and ACS episodes per year) over a 4-year follow-up period. These patients were selected for analysis to evaluate sustainability of clinical and hematological HU response in routine practice. Demographic data and Hb genotypes are displayed in table 1. The children group was mainly composed of βS/βS patients, while adults were mainly βS/βS and βS/β-thal patients. As shown in figure 1 and 2, there was a dramatic reduction in the number of VOC >48h and ACS episodes (-79%) from year 1 in adults and children, with results comparable to previous randomised clinical trials in adults (Charache et al., 1995) and children (Jain et al, 2012). Overall, the reduction in number of VOC (>48h) and ACS was stable over the 4 years of follow-up. This reduction is inversely proportional to the increase in HbF. There were however a moderate rebound in children from year 2 while adults remained stable. Similarly, there was reduction in the proportion of adults and children requiring transfusion (figure 3). The clinical benefit of HU was higher in severe forms of SCD, as displayed by the markedly reduced number of patients with ≥ 3 VOC episodes (>48h)/year at year 1 (figure 4). Hematological response to HU was evidenced as soon as year 1 with a marked increase in HbF% (+6-10) and were maintained over subsequent years of treatment (figure 1 and 2) as the dose of HU was further increased. While there was no striking differences in HbF% variation between age groups and genotypes, the requirement for increase in HU dose over the 4 years of follow-up was markedly higher in children, probably reflecting the different severity between the two population at entry (figure 5). The red cell red cell mean corpuscular volume (MCV) could be used as a measurement of compliance, showing differences between age group (figure 5). There was, as expected, an apparent negative correlation between induction of HbF synthesis and number of VOC >48h and ACS episodes at year 1, attesting to reduced effectiveness of treatment in some patients (figure 6). Improvement in blood parameters was accompanied by mild reduction of absolute neutrophil and platelet count although not to the point of myelosuppression (defined as ANC < 2 x 109/L), showing that MTD was not targeted in routine practice. Treatment-emergent adverse reactions occurring in the 147 patients of the cohort over the 4 years of follow-up were consistent with the known safety profile of hydroxyurea. The commonest effects included neutropenia and thrombocytopenia (25 events in 13 patients) and were easily manageable with temporary discontinuation of treatment. No tumorigenesis was reported. In conclusion, preliminary results from ESCORT-HU in 147 patients treated with HU showed sustained hematological and clinical response while MTD was not targeted, with differences between adults and children which may be attributed in part to reduced compliance in the latter group. Disclosures Voskaridou: Celgene Corp: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acceleron: Membership on an entity's Board of Directors or advisory committees, Research Funding. Oevermann:Addmedica: Membership on an entity's Board of Directors or advisory committees. Thuret:Addmedica: Research Funding; bluebird bio: Research Funding; Novartis: Research Funding. Steschenko:Novartis: Membership on an entity's Board of Directors or advisory committees.

Deferoxamine (DFO) is an iron chelator used to treat iron overload in patients receiving chronic blood transfusions, and is usually administered as overnight subcutaneous infusions. ISOSFER was a prospective, observational, cross-sectional study conducted in metropolitan France that evaluated patient characteristics, quality of life (QoL), compliance and patient satisfaction with DFO monotherapy. Of 70 patients with either thalassemia, sickle cell disease or myelodysplastic syndromes, 30% were 'satisfied' or 'very satisfied' with DFO. Patients' SF-36 scores were lower than those of the general French population, and lower among patients with comorbidities and those dissatisfied with treatment. Although 72% of patients had good compliance to DFO, 57% reported missing at least one infusion in the previous month, and 82% of patients expressed a preference for oral therapy. These results suggest that QoL is severely compromised in patients receiving DFO, and that compliance is not optimal.