ALL-154: t(1;19)(q23;p13) TCF3-PBX1 May Not Be an Intermediate-Risk Subtype in Adult B-Cell Precursor Acute Lymphoblastic Leukemia Patients Treated With MRD-Oriented Protocols from the PETHEMA Group

Abstract

Context: There is a debate regarding the impact of t(1;19) (q23;p13) in adult BCP ALL. While the MD Anderson group suggests it may be a low-risk subtype, the German, English, and French study groups have shown no differential outcome, and Italian and SWOG groups have reported poor outcomes. Objective: To analyze the frequency and clinical impact of t(1;19) in a series of adult BCP ALL patients (pts). Design & Patients: A review of 513 adult BCP ALL pts (15 to 60 years) diagnosed between 2003 and 2017 and treated with MRD-oriented protocols of the PETHEMA Group. Interventions: G-banding and FISH were performed on BM samples. Measurable residual disease (MRD) was centrally assessed by multi-parametric flow cytometry. Main Outcomes Measures: Complete response (CR), overall survival (OS) and cumulative incidence of relapse (CIR), assessed by competing risk analysis. Results: Total of 26 pts with t(1;19)/TCF3-PBX1 (representing 5% of all BCP ALL). 9/23 (39%) cases showed isolated t(1;19) while 14/23 (61%) had additional chromosomal aberrations (ACA). Pts with t(1;19) were more likely to be female (73% vs 45%, p=0.006) and pre-B phenotype (63% vs 17%, p Conclusions: Although showing favorable initial treatment response, pts with t(1;19) experience a higher rate of relapse (especially those with ACA to t(1;19)) than the remaining BCP ALL pts, without differences in OS. A deeper genetic analysis may identify markers of poor outcome enabling a more precise risk stratification of t(1;19) pts.