Application And Sensitivity Comparison Of Three Minimal Residual Disease Detections In Children With B-lineage Acute Lymphoblastic Leukemia

Objective: We applied immune repertoire sequencing technology(IR-SEQ), real-time quantitative polymerase chain reaction(RQ-PCR) and flow cytometry(FCM) for detection of minimal residual disease(MRD) in children with B-lineage acute lymphoblastic leukemia, and compared sensitivities of the three methods.Methods: The three methods were used to detect MRD of bone marrow samples before and after induction treatment(day 0, 15,33 and 64 or 92) from 31 pediatric patients diagnosed as B-ALL in department of hematology in Shenzhen children’s hospital from January 2014 to April 2015. The differences for positive rates among the three methods were analyzed by Chi-square Test,P values <0.05 was accepted as significant.Results: 1.The thirty-one children with newly diagnosed B-ALL were enrolled in this study, including 20 males and 11 females; Ig H gene rearrangement was investigated in the 31 cases, of which 15 cases(48.3%) had one pathogenic clone, and two kinds of pathogenic clones were detected in the other 16 cases(51.6%). 2.On day 15 of remission induction therapy, MRD was measured by IR-SEQ, RQ-PCR and FCM(n=26,25,24), the positive rate was 100%(26/26), 100%(25/25) and 79%(19/24), respectively, in 5 samples, MRD was positive by sequencing and RQ-PCR, but no positive results by flow cytometry. On day 33, MRD was also measured by the above three methods, 6/21(28.6%)samples were MRD-negative by sequencing, 17/21(81%)by FCM, 9/19(47.4%)by RQ-PCR. In 4 samples at the end of remission induction therapy(day 64 or 92), MRD was undetectable by FCM and RQ-PCR, but 2 of the 4 samples were positive by IR-SEQ. 3. Comparisons of the three methods, there was a significant difference between IR-SEQ and FCM(P<0.01); no significant difference between IR-SEQ and RQ-PCR method(P=0.063); a significant difference were shown between FCM and RQ-PCR(P<0.01).Conclusion: IR-SEQ in the detection MRD in children with B-lineage ALL is the most sensitive way, but its significance of IR-SEQ need to be further evaluated in long-term prognosis of ALL patients.