Our findings suggest that anti-CD19 CAR-T cells therapy with a remarkable MRD eradicating ability might be an effective option for patients with relapsed and refractory E2A-PBX1 positive B-ALL.
Taken all together, E2A-PBX1 expression determined by real-time quantitative reverse transcriptase polymerase chain reaction (RQ-PCR) could be used to evaluate MRD status after allo-HSCT.
Patients with E2A-PBX1 showed a favorable treatment response with a lower minimal residual disease (MRD) level (< 10-4) at the time point 1 (TP1, p = 0.039) and the highest proportion of the 5-year EFS, RFS, and OS.
Patients with TEL-AML1 and E2A-PBX1 fusion genes or other B cell precursor ALLs (BCP-ALL) had favorable clinical features, were sensitive to prednisone, had low minimal residual disease (MRD), and an excellent prognosis, with a 5-year event-free survival (EFS) of 84-92%.
We conclude that qualitative detection of MRD by amplification of E2A-PBX1 chimeric mRNAs at the end of consolidation was not significantly predictive of outcome for children treated on POG 9005/9006 and that such results should not be used to alter therapy for patients with t(1;19)+ ALL.
Molecular evidence of E2A/PBX1 fusion transcripts was also observed in a patient in whom a t(1;19) was not detected cytogenetically and in one patient with subclinical levels of minimal residual disease before overt clinical relapse.