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3904 Circulating Erythroblasts Are Associated with Specific Characteristics in Adult Patients with Sickle Cell Disease: The Drepablast Study

Program: Oral and Poster Abstracts
Session: 114. Sickle Cell Disease, Sickle Cell Trait, and Other Hemoglobinopathies, Excluding Thalassemias: Clinical and Epidemiological: Poster III
Hematology Disease Topics & Pathways:
Sickle Cell Disease, Research, Adult, Translational Research, Hemoglobinopathies, Diseases, Human, Study Population
Monday, December 9, 2024, 6:00 PM-8:00 PM

Ugo Boccadifuoco1*, Ivan Lerner, MD2,3,4*, Auria Godard, PhD5,6*, Laure Joseph, MD6,7*, Wassim El Nemer, PhD5,6, Geoffrey Cheminet, MD1,6,8* and Jean-Benoit Arlet, MD, PhD1,6,8,9*

1Department of internal medicine, French Sickle Cell Disease Referral Center, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
2Department of Medical Informatics, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
3Inserm, Centre de Recherche des Cordeliers, Sorbonne Université, Université Paris Cité, Paris, France
4HeKA, Inria Paris, Paris, France
5Établissement Français du Sang PACA-Corse, Aix Marseille Université, CNRS, UMR 7268 ADES, Marseille, France
6Laboratory of Excellence GR-Ex, Paris, France
7Biotherapy Department, French National Sickle Cell Referral Center, Hopital Necker, AP-HP, Paris, France
8Université Paris Cité, Inserm U1163, Imagine Institute, Laboratory "Molecular mechanisms of hematological disorders and therapeutic implications", Paris, France
9Université Paris Cité, Faculté de Santé, Paris, France

Introduction

Circulating erythroblasts (cEB) in the peripheral blood of patients with sickle cell disease (SCD) may be detected in acute situations such as vaso-occlusive events or at steady-state, and the significance of their presence in this context is unknown. Our objective was to compare clinical and biological characteristics of adult patients with SCD depending on the presence or not of cEB at steady state.

Methods

We conducted a monocentric, retrospective, observational study in a French Referral Center, involving patients ≥ 18 years with SCD, who had at least two visits (with a minimum interval of 3 months) at steady state (consultation or day hospital), with a biological evaluation comprising a complete blood count, between 01/01/2017 and 07/31/2023. Two groups of patients were defined: presence (cEB+) or absence (cEB-) of cEB (threshold: 1/100 leukocytes) at inclusion. Visits occurring after a transfusion within 3 months or after a bone marrow transplantation were excluded. Data were extracted from the hospital's clinical data warehouse and the diagnosis of hospitalized vaso-occlusive crisis (HVOC) was determined based on the presence of the International Classification of Diseases code D57.0. Continuous variables were compared using Kruskal-Wallis rank sum test, categorical variables with Pearson’s Chi-squared test, and ordinal variables with trend test. P-values of baseline covariates were adjusted for multiple comparisons following the Benjamini and Hochberg procedure of false discovery rate. Time to new HVOC was analyzed using Cox proportional Hazard model.

Results

We included 384 patients with a median age of 26.0 [19.5;34.1] years: 201 (52.3%) women, 278 (76.8%) had HbSS, 60 (16.6%) HbSC, 9 (2.5%) HbS/β0-thalassemia, and 15 (4.1%) HbS/β+-thalassemia genotype, respectively. Median age, sex ratio or rate of chronic complications showed no statistically significant difference between the 2 groups. Patients with cEB+ (n = 212, 55.2%) more often had a history of acute chest syndrome (158/212 (74.5%) vs 100/172 (58.1%), p <0.001) and HbSS or HbS/β0-thalassemia genotype (184/212 (86.7%) vs 103/172 (66.9%), p <0.001). These patients had a lower hemoglobin (Hb) level (8.9 [7.9;10.1] vs 10 [9.1;11.4] g/dL, p <0.001), a higher mean corpuscular volume (MCV) (88.5 [79;98] vs 79 [70;89] fL, p <0.001), a higher reticulocyte count (224 [149;307.5] vs 159 [112;241.5] G/L, p <0.001) and a higher ferritin level (136 [55;287] vs 58 [32;168], p <0.001). Lactate dehydrogenase (LDH) and total bilirubin levels were also higher in cEB+ patients: 378 [292;504] vs 320 [250;425] UI/L, p <0.001; 41 [25;67] vs 29 [19.8;46.2] µmol/L, p <0.001, respectively.

In the HbSS and HbS/β0-thalassemia population (n=287), cEB+ patients (n=184, 64.1%) had no specific clinical features but a significantly lower Hb level (8.7 [7.7;9.8] vs 9.4 [8.4;10] g/dL, p = 0.033), a higher MCV (90 [81;99] vs 85 [78;92] fL, p = 0.011) and a higher ferritin level (150 [62;305.8] vs 73 [36;254] µmol/L, p = 0.048). Moreover, higher cEB (in logarithmic scale) correlated linearly with lower Hb (g/dL) level and higher MCV (fL) values. No significant difference were observed between cEB+ and cEB- patients concerning reticulocyte count (233 [154.5;319.5] vs 211 [146;263.5] G/L, p = 0.102), LDH (409 [319;521.8] vs 364 [293;467] UI/L, p = 0.115), total bilirubin (44 [28;70] vs 37 [26;56] µmol/L, p = 0.277), hydroxyurea use, β-globin haplotype distribution or presence of alpha-thalassemia. In multivariate analysis, during follow-up, every increase of 10% of cEB was independently associated with a shorter time to a new HVOC (HR 1.015 (IC 95 [1.003-1.028]), p = 0.02).

We characterized cEB of 5 HbSS patients by flow cytometry and May-Grünwald Giemsa staining. cEB represented all stages of terminal erythroid differentiation, with similar proportions to those of the bone marrow. In vitro erythroid differentiation of circulating CD34+ cells from cEB- and cEB+ patients showed accelerated differentiation in cEB+ patients.

Conclusion

The presence of cEB in adult patients with SCD appears as a frequent feature (more than half of patients) and is associated with lower Hb level with inadequate reticulocyte response, higher MCV, and shorter time to a new HVOC, but not with chronic complications. Other studies are needed to better characterize these cEB, and to better explore dyserythropoiesis in this population as suggested by our preliminary results.

Disclosures: Godard: Agios: Research Funding. Joseph: Vertex: Honoraria; GBT: Honoraria; Addmedica: Honoraria; Novartis: Honoraria. El Nemer: Agios: Research Funding; LGD SARL: Consultancy; Imalia SA: Consultancy. Arlet: Addmedica: Research Funding; GBT-Pfizer: Honoraria, Research Funding; Vertex: Research Funding; Novartis: Honoraria, Research Funding.

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