Objective: To study the effects of minimal residual disease (MRD) level on day 33 of remission induction and IKZF1 genotype on the survival of children with B-lineage acute lymphoblastic leukemia (B-ALL).
Methods: A total of 152 children with newly-diagnosed B-ALL who had complete remission after the first cycle of the chemotherapy and had complete follow-up information were enrolled in this study. According to the MRD detection by flow cytometry on day 33 of remission induction, they were divided into three groups: standard-risk (SR) group (MRD <10-4; n=60), intermediate-risk (IR) group (10-4≤ MRD <10-2; n=55), and high-risk (HR) group (MRD ≥10-2; n=37). Nested RT-PCR was used to determine the IKZF1 genotype of all children before chemotherapy. The effects of MRD level on day 33 of remission induction and IKZF1 genotype on the recurrence-free survival (RFS) of children with B-ALL were analyzed.
Results: There were 7 common IKZF1 subtypes in all the 152 children with B-ALL: IK1, IK2/3, IK4, IK6, IK8, IK9, and IK10. Of the 152 children, 130 had functional subtypes of IKZF1 and 22 had non-functional subtypes of IKZF1. During the follow-up period, relapse occurred in 26 (17%) children, and the recurrence rate was highest in the HR group (P<0.05). However, there was no significant difference in the recurrence rate between the SR group and the IR group (P>0.05). The cumulative recurrence rate of the children with non-functional subtypes of IKZF1 was significantly higher than that of those with functional types of IKZF1 (P<0.01). The predicted 5-year RFS rates in the SR, IR, and HR groups were (94.2±2.9)%, (86.7±3.8)%, and (56.2±4.5)% respectively (P<0.05). The 5-year RFS rate of the children with functional subtypes of IKZF1 was significantly higher than that of those with non-functional subtypes of IKZF1 (P<0.01). There was no significant difference in the predicted 5-year RFS rate between the children with functional subtypes of IKZF1 and those with non-functional subtypes of IKZF1 in the SR group (P>0.05). However, the predicted 5-year RFS rate of the children with functional subtypes of IKZF1 was significantly higher than that of those with non-functional subtypes of IKZF1 in the IR group and the HR group (P<0.05).
Conclusions: B-ALL children with non-functional subtypes of IKZF1 have a high recurrence rate, and the recurrence rate will be even higher in B-ALL children with non-functional subtypes of IKZF1 and MRD ≥10-4 on day 33 of chemotherapy.
目的: 研究诱导缓解第33天微小残留病（MRD）与IKZF1基因型对于儿童急性B淋巴细胞白血病（B-ALL）生存率的影响。
方法: 以第一疗程化疗获得完全缓解且有完整随访信息的152例初诊B-ALL患为研究对象。采用流式细胞术检测化疗第33天MRD，并分为3组：残留白血病细胞 < 10-4者为MRD标危组（60例），10-4 ≤ MRD < 10-2为MRD中危组（55例），MRD ≥ 10-2为MRD高危组（37例）。应用巢式RT-PCR检测化疗前所有患儿的IKZF1基因型。分析诱导缓解第33天MRD及IKZF1基因型对B-ALL患儿无复发生存率的影响。
结果: 152例初诊B-ALL患儿有7种常见IKZF1基因亚型：IK1、IK2/3、IK4、IK6、IK8、IK9和IK10，其中130例表达IKZF1基因功能亚型、22例为IKZFl基因功能缺失亚型。随访期间26例（17%）患儿复发，以高危患儿复发率最高（P < 0.05），而标危、中危组复发率的差异无统计学意义（P > 0.05）。IKZFl基因功能缺失亚型阳性患儿的累计复发率高于IKZFl基因功能亚型阳性的患儿（P < 0.01）。MRD标危、中危、高危患儿的预计5年无复发生存率分别为（94.2±2.9）%、（86.7±3.8）%和（56.2±4.5）%，三组间的差异均有统计学意义（P < 0.05）。IKZFl基因功能亚型阳性患儿的5年无复发生存率高于功能缺失亚型阳性患儿（P < 0.01）。MRD标危组IKZFl基因功能亚型阳性患儿的预计5年无复发生存率与功能缺失亚型阳性患儿的差异无统计学意义（P > 0.05），中危组和高危组中IKZFl基因功能亚型阳性患儿的预计5年无复发生存率均高于功能缺失亚型阳性患儿（P < 0.05）。
结论: IKZFl基因功能缺失亚型阳性的B-ALL患儿复发率高，尤其是化疗第33天MRD ≥ 10-4的IKZF1基因功能缺失亚型阳性B-ALL患儿。