B09 | HIGH CURE RATES AND LOW CHRONIC GVHD INCIDENCE ACROSS ALL AGES FOLLOWING ALLOGENEIC TRANSPLANTATION FOR SICKLE CELL DISEASE: REAL-WORLD EVIDENCE (2010–2021)

Background: Allogeneic hematopoietic cell transplantation (HCT) remains the most common curative treatment for sickle cell disease (SCD), though emerging gene therapies are providing alternatives. Real-world data from international registries is crucial for informed decision-making. Methods: Data from pediatric and adult SCD patients receiving their first HCT between January 2010 and December 2021 were extracted from the EBMT Hemoglobinopathy registry. Only first transplants were included. Data are reported as medians with ranges, and event-free survival (EFS), graft-versus-host disease-free survival (GRFS), and overall survival (OS) were analyzed using Kaplan-Meier. Results: A total of 1,815 patients, treated at centers across 36 countries in Europe, Asia, and Africa, were included: 1,331 children (up to 18 years) and 484 adults. Median transplant age was 9.6 years for children (range 1.1–18) and 26.5 years for adults (18–49.2). Of the children, 52% were male and 48% female, while 51.5% of adults were male and 48.5% female. The distribution of transplant types included 1,066 matched related (80.5%), 144 mismatched related (10.6%), and 115 unrelated (8.7%) transplants for children, and 401 matched related (83%), 72 mismatched related (14.9%), and 10 unrelated (2.1%) for adults. After a median follow-up of 24 months, 2-year OS and EFS were 95.7% (94.3–96.7) and 92.9% (91.3–94.3) for children, and 93.7% (91–95.7) and 80.8% (87.3–93) for adults. The incidence of acute grade III/IV GVHD was 3.9% (2.4–6) in children and 8.4% (7.2–9.6) in adults, while chronic GVHD occurred in 4.1% (2.5–6.3) of children and 4.4% (3.5–5.6) of adults. Multivariate analysis showed age significantly impacted OS (12-18 years HR 2.01 [1.01-3.99, p = 0.047]; >18 years HR 2.47 [1.23-4.94, p = 0.01]), but not acute or chronic GVHD incidence, which did not affect GFRS. The year of transplant significantly influenced OS (HR 0.59 [0.37-0.93, p = 0.02]) and reduced the risk of acute GVHD (HR 0.66 [0.44-1.04, p = 0.07]) and chronic GVHD (HR 0.54 [0.34-0.86, p = 0.01]) for transplants after 2015. Conclusions: Real-world data supports the effectiveness of allogeneic HCT as a curative treatment for SCD across all ages with high cure rates irrespective of age, likely due to the high proportion of adults using reduced intensity regimens with GVHD prevention strategies. The incidence of severe chronic GVHD is low irrespective of age.