Role of BCR-ABL1 isoforms on the prognosis of Philadelphia chromosome positive acute lymphoblastic leukemia in the tyrosine kinase inhibitor era: A meta-analysis

BCR-ABL1 fusion gene is the driver mutation of Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL). Although the prognostic value of BCR-ABL1 isoforms in Ph+ ALL patients has been investigated in numerous studies in the tyrosine kinase inhibitor (TKI) era, the results were still conflicting. Hence we performed herein the meta-analysis to comprehensively assess the impact of BCR-ABL1 isoforms on the clinical outcomes of Ph+ ALL patients. Systematic literature review was conducted in PubMed, Embase, and Cochrane databases with the data access date up to June 15, 2020. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated with fixed-effects or random-effects models. Furthermore, subgroup analyses were performed to assess the robustness of the associations. Nine studies with a total number of 1582 patients were eligible for this meta-analysis. Combined HRs suggested that p210 was slightly associated with inferior event-free survival (EFS) (HR = 1.34, 95% CI 1.05–1.72). The overall survival (OS) was not significantly affected (HR = 1.15, 95% CI 0.92–1.45). In subgroup analyses, the HRs showed a trend toward adverse impact of p210 on clinical outcomes. However, the confidence intervals were not crossing the null value only in a minority of subgroups including Caucasian studies, first-generation TKI treated cohort and transplant cohort. Our findings suggested that p210 might pose a mild adverse impact on the EFS of Ph+ ALL patients. This effect might be compromised by the use of second- or third-generation TKIs. Further studies are needed to verify our conclusions.