Abstract
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.