Reduced intensity conditioning with 8 Gy total body irradiation in adult patients with acute lymphoblastic leukemia

Total body irradiation (TBI) plus chemotherapy is commonly applied prior to allogeneic hematopoietic stem cell transplantation (SCT) for patients with acute lymphoblastic leukemia (ALL). Here, we retrospectively analyzed registry data from the German Multicenter Study Group for Adult ALL (GMALL) and report the outcomes for 111 adult ALL patients who received 8 Gy TBI-based SCT conditioning in first complete remission between 2002 and 2018 after initial treatment with pediatric-based approaches. Patients had a median age of 52 years (range 18-65) at initial diagnosis, and the majority of patients (93%) had a good performance status (ECOG 0/1). 97 patients (87%) showed high-risk features according to GMALL criteria, of whom 58 (60%) were Philadelphia chromosome/BCR::ABL1-positive. With a median follow-up of 3.1 years after SCT, the survival rates at one, three, and five years were 72%, 64%, and 57% for disease-free survival, and 76%, 67%, and 61% for overall survival, respectively. The rates of non-relapse mortality at one, three, and five years were 22%, 26%, and 30%, while the cumulative incidences of relapse were 7%, 10%, and 14%, respectively. In summary, 8 Gy TBI conditioning in ALL patients was feasible and resulted in outcomes similar to those previously reported for 12 Gy conditioning regimens.