ESTRO 2024 - Abstract Book

S1147

Clinical - Haematology

ESTRO 2024

paediatric patients (1).The aim of this large database study is to assess whether the TBI-based protocols are superior to CT alone conditioning protocols for allo-HSCT in ALL adult patients.

Material/Methods:

This European retrospective study included adult patients with ALL who underwent HSCT registered in the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) database and treated between 1979 and 2019. The cohort included 4571 patients from 70 hospitals treated with HSCT for ALL. The median age was 34.1y (range: 18-75.7). The majority of patients were male (61%) and related to the donor (59.5%). Most patients had B-ALL (79%) and received conditioning based on TBI (77%) with a myeloablative radiation schedule (80%). The mean and median TBI doses were 10.8 ± 2.5Gy and 12Gy (range, 2-14.85Gy), respectively. Overall, 61% of the patients were grafted after the first complete remission Primary endpoints include overall survival (OS), leukemia-free survival (LFS), relapse incidence (RI), and non-relapse mortality (NRM). Univariate analyses were performed using the Gray test for the cumulative incidence of NRM and RI and the log-rank test for OS and LFS. A Cox proportional hazards model was used for multivariate regression. After a median follow-up of 71 months, all oncological outcomes were improved after TBI-based conditioning compared to CT alone regimens. The 5-year OS, LFS and RI were 47.5% vs. 36.1%, (p < 0.0001), 44.5% vs. 29.1% (p < 0.0001) and 47.5% vs. 57.7% (p < 0.0001) in the TBI and the CT alone groups respectively. The 5-year cumulative incidence of NRM was 30% with TBI versus 30.1% with CT alone (p=0.38). In the multivariate analysis, TBI was an independent parameter for better outcomes in terms of OS (HR=0.87 (CI 95% [0.77 – 0.98]; p=0.03), LFS (HR=0.82 (CI 95% [0.73-0.93]; p=0.001) and RI (HR=0.75 (CI 95% [0.64-0.87]; p=0.0003). The other unfavorable prognostic factors for OS were: age > 40 (HR=1.42; CI 95% [1.29-1.57]; p=0.001), male gender (HR=1.12; CI 95% [1.03-1.22]; p=0.004), year of transplant before 2008 (HR=0.62; CI 95% [0.57-0.68]; p<0.0001), graft after CR > 2 (HR=0.44; CI 95% [0.4-47.7] p<0.0001). For NRM the unfavorable prognostic factors were: age > 40y, year of transplant (before 2008) and disease status at transplant (no CR1). There was no impact of type of conditioning regimen. In terms of cGVHD, gender, BCR/ABL status and year of transplant were independent prognostic factors in multivariate analysis. Results: