Purpose: In the Acute Lymphoblastic Leukemia (ALL) landscape, Adolescents and Young Adults (AYA) often present high-risk diseases and increased chemotherapy-related toxicity. Studies analyzing outcomes of AYA after Hematopoietic Stem Cell Transplant (HSCT) are scarce. Our study aimed to compare the outcomes of children and AYA with ALL after HSCT and to determine factors influencing potential differences.
Method: 891 patients, from the SFGM-TC registry, aged between 1 and 25 years who received HSCT between 2005 and 2012 were included. Outcomes of AYA were compared to the ones of their younger counterparts.
Results: Five-year OS and GRFS were lower in AYA: 53.1% versus 64% and 36% versus 47% (p = 0.0012 and p=0.007 respectively). While CIR were similar in both groups, 5 year-Treatment Related Mortality was higher in AYA: 19% versus 13% (p=0.04). The lower GRFS in AYA was mainly explained by a higher chronic Graft versus Host Disease (cGvHD) incidence: 32% versus 19% (p<0.001). Use of Peripheral Blood Stem Cells and use of anti-thymoglobulin appeared to be the main factors impacting cGvHD occurrence in AYA.
Conclusion: AYA have worse outcomes than children after HSCT for ALL because of a greater risk of TRM due to cGvHD. HSCT practices should be questioned in this population.