Outcomes of allogeneic stem cell transplant in adult Philadelphia negative acute lymphoblastic leukemia patients treated with the pediatric-inspired GIMEMA 1913 protocol. A Campus ALL study.

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the best consolidative treatment for high-risk acute lymphoblastic leukemia (ALL). The Campus ALL study group analyzed the clinical outcomes of patients treated in the real-life with the pediatric-inspired and minimal/measurable residual disease (MRD)-oriented GIMEMA LAL1913 protocol who underwent alloHSCT. Key factors impacting on outcomes were MRD and remission status (1 complete remission vs 2 complete remission) at transplant. MRD positivity was associated with poorer outcomes, with 3-year overall survival (OS) and disease-free survival (DFS) of 47% and 41% in MRD-positive patients compared to 80% and 70% in MRD-negative patients. Additionally, MRD negativity was associated with improved outcomes also for patients in 2nd complete remission with 3-year OS and DFS rates of 60% and 56%, respectively, compared to only  13% for both outcomes in MRD-positive cases. Patients older than 55 years showed survival rates comparable to younger patients, despite having a slightly higher non-relapse mortality, which remained below 20% at 3 years. These findings underscore the crucial role of alloHSCT in high-risk ALL and emphasize the importance of an early accurate disease risk allocation. The adverse outcome observed with MRD positivity advocates for early pre-transplant intervention with immunotherapy, whenever possible.