Clinical characteristics and outcomes of mixed phenotype acute leukemia with Philadelphia chromosome positive and/or bcr-abl positive in adult

Knowledge of mixed phenotype acute leukemia (MPAL) with t(9;22)(q34;q11.2) and/or bcr-abl (Ph-positive MPAL) is limited. In this report, we review 21 adult patients with Ph-positive and/or bcr-abl positive MPAL. They were predominantly male, and presented with high WBC counts; 61.9% patients had WBC counts higher than 30 × 10⁹/L, and 33.3% patients had WBC counts higher than 100 × 10⁹/L. Electron microscopy (EM)-determined positivity for myeloperoxidase (MPO) should be considered for the classification of acute leukemia because MPO was positive by EM and flow cytometry only in 14.3% of cases in our study. Six cases (30.0%) had additional chromosome aberrations. Expression of p190 ^bcr-abl was more common than that of p210 ^bcr-abl . There was no difference in characteristics between the p190 ^bcr-abl positive and p210 ^bcr-abl positive groups. The overall complete remission (CR) rate was 81.0%. Females, and patients with high WBC (>100 × 10⁹/L) at baseline had lower CR rate (57.1, 57.1%, respectively). The treatment outcome of Ph-positive MPAL is poor; the 1-year overall survival (OS) and relapse-free survival (RFS) rate were 28.0 and 18.0%, respectively. Imatinib and allogeneic hematopoietic stem cell transplantation can improve survival with Ph-positive MPAL.