C022 | REAL-WORLD OUTCOMES OF HEMATOPOIETIC CELL TRANSPLANTATION IN TRANSFUSION-DEPENDENT THALASSEMIA (2010–2021): AGE AS A KEY FACTOR FOR GVHD-FREE, RELAPSE-FREE SURVIVAL. ANALYSIS OF THE EBMT HEMOGLOBINOPATHY WORKING PARTY

INTRODUCTION: Allogeneic hematopoietic cell transplantation (HCT) is the only diffuse curative option for transfusion dependent thalassemia(TDT). Here we report an updated analysis of the EBMT Hemoglobinopathy Registry limited to the 2000-2010 period. METHODS: Data on patients with TDT receiving HCT from January 2010 to December 2021 were extracted.Data are expressed as median with range.Event free survial and GRFS (abcence of second HCT,grade III-IV acute and extensive chronic GVHD)and overall survival (OS) were evaluated using Kaplan-Meier.Differences between outcomes were tested by log-rank and Gray tests and multivariable Cox models were using for adjustement including age at HCT in class, year in periods and donor type. RESULTS: 2,807 consecutive patients were transplanted: 2,601 children (up to 18 years of age) and 206 adults. Median age at transplant was 6.7 years (range 0.5-18)for children and 22.1 years (18-44.8) for adults.The numer of matched related, mismatched related and unrelated transplants were 1,879 (72.7%), 156 (6%) and 551 (21.3%) for children and 143 (69.4%), 14 (6.8%) and 49 (23.8%) for adults. 69.2% of children received bone marrow as the stem cell source whereas 59.3% adults received PBSC. After a median follow up of 24 months, the 2 years OS and EFS were 92.1% (90.8-93.3) and 87.4% (85.7- 88.9) for children and 84.4% (78.1-89) and 80.8% (73.9-86.1) for adults, respectively.Acute GVHD grade III/IV and chronic GVHD extensive occurred in 8.4% (7.2-9.6) and 4.4% (3.5-5.6) of children and 9.5% (5.8-14.3) and 7.2% (3.5-12.7) of adults, respectively. In multivariable analysis, impact of age of patient and donor type were statistically significant for age on overall survival and both on overall and severe GVHD; whereas year of HCT(before or after 2015) had a significant protective effect on severe chronic GVHD and overall survival. Compared to the class 0-4 years old, the impact on GRFS of age were HR 0.87 (0.65-1.16, p= 0.33) for the group 4-7years, HR 0.96 (0.73-1.27, p =0.8) for 7-12 years, HR 1.59(1.2-2.1,p =<0.001) for 12-18 years and HR 1.63 (1.15-2.32, p=0.006) for the group ≥18 years. CONCLUSIONS: These Real world data confirm HCT as curative therapy for TDT with high rate of cure. Age continues to be an important factor for outcome with best GFRS achieved in those transplanted up to 12 years of age. There was significant reduction in the risk of severe chronic GVHD over time despite almost a third of HCT being with alternative donors.