CNS Relapse Risk in Leukemia After Transplant

Central nervous system (CNS) relapse remains a critical challenge in adults with acute lymphoblastic leukaemia after allogeneic haematopoietic cell transplantation. A retrospective analysis of 748 patients from 2009 to 2022 found a 5.1% CNS relapse rate, with a median onset at 10.6 months.

Philadelphia chromosome-positive (Ph+) disease emerged as the strongest predictor, with a 9.7% relapse rate compared to 1.4% in Ph- cases (p<0.001). Hyperleukocytosis at diagnosis also increased risk (8.1% vs. 2.5%).

Patients with negative measurable residual disease pre-transplant had lower CNS relapse rates. Prophylactic intrathecal therapy and total body irradiation reduced risk in Ph- patients.

Survival outcomes were stark: five-year overall survival was 30.4% for isolated CNS relapse versus 7.6% for other patterns-highlighting improved prognosis when CNS is the sole site of recurrence.