单细胞测序技术探索儿童B-ALL克隆演化规律和复发机制

B-cell acute lymphoblastic leukemia is the most common malignancy affecting children. Outcomes for children improved over the last 50 years due to the advent of multidrug, risk-adapted chemotherapy and the recognition of clinical, biological, and treatment response characteristics that identify patients at risk for treatment failure. Cure rate are now approximately 85%. However, the prognosis for the 10-15% of children who relapse remains dismal and has not improved over the past two decades. Clonal evolution and drug resistance drive the initiation of relapse of pediatric B-ALL. However, the mechanism of clonal evolution and resistance upon chemotherapy drugs are still unclear. In our previous study, we had investigated the clonal evolution and drug resistance via whole genome sequence, RNA sequence and single cell transcription sequence and we found that mutation of PDGFRB C843 played a critical role in the drug resistance. Based on this study, we plan to investigate the clonal evolution and drug resistance of relapse B-ALL via whole genome sequence, RNA sequence and single cell transcription sequence of 8 relapsed B-All samples. Out study will clarify the clonal evolution and the mechanism of B-ALL relapse and shed light on the precise therapy of relapse pediatric B-ALL patients.

B细胞急性淋巴细胞白血病（B-cell acute lymphoblastic leukemia，B-ALL）是最常见的儿童恶性肿瘤。基于危险度分层治疗的诊疗方案已经使得儿童B-ALL的5年总体生存率上升至85%以上，但仍有10-15%的患儿发生复发。克隆演变是B-ALL复发的内在动力，化疗耐药是B-ALL复发的本质，但克隆演变的规律和化疗耐药的机制尚不完全清楚。在前期工作中，通过对一名复发B-ALL患儿进行多组学测序，我们初步发现了B-ALL克隆演变的规律及耐药复发的机制。在此基础上，本课题拟对8名复发B-ALL患儿初诊、缓解和复发等不同时间点白血病细胞进行全基因组，转录组和单细胞转录组测序，结合大规模临床标本验证及体内外功能实验，揭示复发B-ALL克隆演化规律及复发机制，筛选靶向小分子化合物，开发精准治疗复发B-ALL的诊疗方案，提升我国儿童B-ALL的诊疗水平。

化疗后持续存在的微小残留疾病是血液学恶性肿瘤和实体癌最有价值的预后指标。不幸的是，由于残留细胞的稀少性和异质性，我们对微小残留疾病引起的耐药性的研究目前还十分有限。在这里，我们生成了161986个单细胞转录组，通过结合单细胞RNA测序和B细胞受体测序结果，对比分析了儿童B细胞急性淋巴细胞白血病（B-ALL）在初诊、残留和复发时的动态变化。与初诊时相比，复发时的白血病细胞倾向于转移到低分化状态，而残余细胞的变化更为复杂。差异分析结果表明残余细胞、耐药克隆和具有MLL重排的B-ALL中缺氧信号通路的激活。随后体外和体内实验均证实，缺氧信号通路的抑制使白血病细胞对化疗药物更为敏感。因此这种微小残留疾病的单细胞分析为确定B-ALL的有效治疗机会开辟了一条途径。