Pediatric acute lymphoblastic leukemia with t(1;19)/TCF3-PBX1 in Taiwan

Area of Science:

• Pediatric Oncology
• Hematology
• Genetics

Background:

• The t(1;19)(q23;p13.3) translocation with TCF3-PBX1 fusion is a frequent genetic alteration in childhood acute lymphoblastic leukemia (ALL).
• Historically associated with a poor prognosis, intensive treatment strategies have improved outcomes for this subtype.
• This study evaluates the outcomes of Taiwanese children with t(1;19)/TCF3-PBX1 ALL treated with contemporary intensive chemotherapy.

Purpose of the Study:

• To determine the outcome of children with the t(1;19)/TCF3-PBX1 genotype treated with modern intensive chemotherapy.
• To compare the survival and relapse rates of t(1;19)/TCF3-PBX1 ALL patients with other B-ALL subtypes.

Main Methods:

• Analysis of data from the Taiwan Pediatric Oncology Group 2002 ALL studies.
• Genotyping performed using cytogenetic analysis and/or reverse transcriptase polymerase chain reaction (RT-PCR).
• Patients stratified into standard risk (SR), high risk (HR), or very high risk (VHR) groups; t(1;19)/TCF3-PBX1 patients were primarily treated in the HR arm.

Main Results:

• Of 1,129 B-ALL patients, 64 (5.7%) had the t(1;19)/TCF3-PBX1 translocation.
• The 5-year event-free survival for t(1;19)/TCF3-PBX1 ALL was 83.3%, comparable to TEL-AML1 (85.2%) and hyperdiploidy >50 (84.0%) ALL.
• The cumulative risk of central nervous system relapse in t(1;19)/TCF3-PBX1 ALL (8.7%) was not statistically significantly higher than in TEL-AML1 (5.8%) or hyperdiploidy (4.1%) ALL.

Conclusions:

• Contemporary intensive chemotherapy has significantly improved outcomes for children with t(1;19)/TCF3-PBX1 ALL.
• Children with this genotype now achieve survival rates similar to those with favorable genetic subtypes like TEL-AML1 and hyperdiploidy.
• While CNS relapse risk may be slightly elevated, it does not negate the overall improved prognosis with current treatment protocols.