Clinical characteristics and prognosis analysis of adult B-cell acute lymphoblastic leukemia with E2A-PBX1 fusion gene positive / 白血病·淋巴瘤

ABSTRACT

Objective@#To investigate the clinical features of adult B-cell acute lymphoblastic leukemia (B-ALL) with E2A-PBX1 fusion gene positive.@*Methods@#The clinical data of 91 Philadelphia chromosome negative B-ALL patients who received chemotherapy regularly in Nanfang Hospital of Southern Medical University from March 2015 to December 2017 were collected. According to the fusion gene detection results, the patients were divided into E2A-PBX1 fusion gene positive group and E2A-PBX1 fusion gene negative group. The clinical features and prognosis of both groups were retrospectively analyzed. And then E2A-PBX1 fusion gene negative group was further divided into MLL-AF4 fusion gene positive group and the other ALL groups,which were compared with E2A-PBX1 fusion gene positive group in the prognosis.@*Results@#There were 11 ALL patients with E2A-PBX1 fusion gene positive, and 80 ALL patients with E2A-PBX1 fusion gene negative. The level of lactic dehydrogenase (LDH) in E2A-PBX1 fusion gene positive group was higher than that in E2A-PBX1 fusion gene negative group [4 063 U/L (1 070- 9 554 U/L) vs. 454 U/L (103- 18 651 U/L), U=-4.700, P < 0.01], and there were no statistically significant differences in age, gender, white blood cell count and extramedullary invasion (all P > 0.05). The immunophenotypes of ALL patients with E2A-PBX1 fusion gene positive were all common B-cell phenotype. Out 4 of 7 ALL patients showed the different expression of Philadelphia-like ALL phenotype CRLF2 or phosphorylated CRKL or phosphorylated STAT5 by using flow cytometry. The complete remission (CR), minimal residual disease (MRD)-negative and the recurrence for 11 cases of E2A-PBX1 fusion gene positive group included 9, 7, 8 cases, respectively after first course of induction chemotherapy. The CR, MRD-negative and the recurrence for 80 cases of E2A-PBX1 fusion gene negative group included 71, 53, 26 cases, respectively after the first course of induction chemotherapy. There were no statistically significant differences in the CR and MRD-negative between the two groups after the first course of induction chemotherapy (P= 0.721, P= 0.487), but there was a statistical difference in the recurrence (χ2= 7.751, P= 0.012). The median follow-up time was 17 months (1-44 months), and the 1-year overall survival (OS) rate and 1-year event-free survival (EFS) rate of E2A-PBX1 fusion gene positive ALL group were lower than those of the negative group (OS 43.6% vs. 70.0%, P= 0.020; EFS 13.6% vs. 60.0%, P= 0.002). Subgroup analysis showed that there were no statistical differences between E2A-PBX1 fusion gene positive group and MLL-AF4 fusion gene positive group in 1-year OS rate and 1-year EFS rate (P= 0.617, P= 0.984).@*Conclusions@#E2A-PBX1 fusion gene positive rate is low in adult B-ALL patients with a good response to traditional chemotherapy in the early stage, but its cumulative recurrence rate is high. It is a high-risk cytogenetic abnormality which is similar to MLL gene rearrangement and needs to explore novel therapy strategies.