Association of CDKN2A/2B deletion with relapse after hematopoietic stem cell transplantation for acute lymphoblastic leukemia

The most important prognostic factor for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) is minimal residual disease (MRD).Previous studies have reported copy number variants of genes such as IKZF1, CDKN2A/2B, and PAX5.These gene mutations can be analyzed using multiplex ligation-dependent probe amplification (MLPA), which is less costly and easier to perform than large-scale gene mutation analyses.In this study, we performed copy number variant analysis of leukemia cells at the first onset of Ph+ALL in a case series of allogeneic hematopoietic stem cell transplantation (allo-HSCT) using the MLPA method.We analyzed how it influenced allo-HSCT prognosis together with MRD information.CDKN2A/2B copy number variations significantly increased the rate of post-transplant recurrence (P=0.025) and significantly reduced disease-free survival (P=0.015).Additionally, patients with IKZF1 deletions had a significantly higher post-transplant recurrence rate (P=0.042).Although they were positive for pre-transplant MRD, no relapse was observed in patients with wild-type copy number variations in IKZF1 or CDKN2A/2B.CDKN2A/2B copy number variation is a crucial factor that can be confirmed at initial onset as a post-transplant prognostic factor of Ph+ALL.