CLINICAL SIGNIFICANCE OF MINIMAL RESIDUAL DISEASE IN CHILDHOOD ALL

越来越多的证据表明，消除微量残留 可检测到的白血病细胞是治愈所必需的。 大量努力 因此，在过去的十年中，开发了敏感的方法， 检测出患者体内残留的这些微小的白血病细胞。 聚合酶 非随机染色体易位的链式反应（PCR）扩增 允许灵敏地检测白血病。 但大多数 儿童急性淋巴细胞白血病（ALL）并没有表现出这种 非随机染色体易位，以及替代策略是 检测微小残留病（MRD）。 在B和T细胞中 ALL通常存在免疫球蛋白（IG）或T细胞的重排 受体（TCR）基因或两者，并且它们的克隆后代携带相同的 重排 这种独特的重排提供了一个目标， MRD的扩增和检测。 此外，竞争性PCR测定可 用于定量评估患者体内的肿瘤负荷。 PCR 在IG重链基因座和TCR δ基因座的分析将是 用于扩增白血病特异性抗原受体。 序列分析 将使我们能够设计连接特异性的 寡核苷酸探针检测和定量白血病负荷 所有的孩子。 这一建议的基本假设是， 诱导和强化治疗期间白血病负荷减少 预测更高的治愈率，消除可检测到的 白血病细胞是治愈所必需的。 为此，我们提出两个具体的建议。 目标。 第一：检测、定量和确定临床 MRD在儿童ALL中的意义，以评估 并确定是否减少的幅度 诱导治疗期间的白血病负荷，如项目4所述， 在随后的治疗中连续预测结果。 为此，我们 还应比较MRD检测的临床效用， 外周血和骨髓，并评估是否检测 寡克隆疾病或克隆进化具有预后意义。 第二：评估儿童MRD检测的临床意义 复发后，使用定量PCR分析评估白血病负荷 并将其与临床结果相关联，并确定 在自体骨髓移植后，根除MRD是治愈的必要条件 移植（ABMT）。 为此，我们将确定临床 患者在治疗时的白血病负担的意义， ABMT后PCR检测自体骨中是否有白血病细胞 免疫净化前后骨髓或外周血干细胞 与不良结局有关。 还将进行PCR分析， 评估项目中概述的新型治疗策略对MRD的影响 1.我们的总体目标是评估检测的临床意义 和MRD的量化，使我们能够识别高风险儿童 同样重要的是， 他们可能已经被治愈了， 疗法 通过这种方法，我们应该能够针对每个人的情况进行治疗。 根据随时间推移的风险来确定每个孩子，从而最大限度地提高 治疗指数

Increasing evidence suggests that the eradication of minimal residual detectable leukemia cells is necessary for cure. Considerable effort has therefore been made over the past decade to develop sensitive methods to detect these minimal residual leukemic cells in the patient. Polymerase chain reaction (PCR) amplification of non-random chromosome translocations permits sensitive detection of leukemia. However, the majority of children with acute lymphoblastic leukemia (ALL) do not demonstrate such non-random chromosomal translocations, and alternative strategies are necessary to detect minimal residual disease (MRD). In both B and T cell ALL there is usually rearrangement of immunoglobulin (Ig) or T cell receptor (TCR) genes or both, and their clonal progeny bear the identical rearrangement. This unique rearrangement provides a target for amplification and detection of MRD. Moreover, competitive PCR assays can be used to assess quantitatively the tumor burden within the patient. PCR analysis at both the Ig heavy chain locus and the TCR delta locus will be used to amplify the leukemia specific antigen receptor. Sequence analysis of the PCR product will enable us to design junctional specific oligonucleotide probes to detect and quantitate leukemic burden in children with ALL. The basic hypotheses of this proposal are that a rapid reduction in the leukemic burden during induction and intensification predicts for a higher cure rate and that the elimination of detectable leukemia cells is necessary for cure. To this end we propose two specific aims. FIRST: to detect, quantitate and determine the clinical significance of MRD in childhood ALL, to assess the leukemic burden at presentation and to determine whether the magnitude of reduction of leukemic burden during induction therapy as outlined in PROJECT 4 and serially throughout subsequent therapy predicts outcome. In this aim we shall also compare the clinical utility of the detection of MRD in peripheral blood and bone marrow and assess whether the detection of oligoclonal disease or clonal evolution has prognostic significance. SECOND: to assess the clinical significance of MRD detection in children after relapse, to assess leukemic burden using quantitative PCR analysis and to correlate this with clinical outcome, and to determine whether the eradication of MRD is necessary for cure after autologous bone marrow transplantation (ABMT). In this aim we shall determine the clinical significance of the leukemic burden in the patient at the time of and after ABMT and whether PCR detection of leukemia cells in autologous bone marrow or peripheral blood stem cells before and after immunologic purging is associated with poor outcome. PCR analysis will also be performed to assess the impact on MRD of novel treatment strategies outlined in PROJECT 1. Our overall goal is to assess the clinical significance of detection and quantification of MRD to enable us to identify children at high risk of subsequent failure, and just as importantly, to identify those children who may already be cured who could then be spared subsequent toxic therapy. With this approach we should be able to tailor treatment to each individual child based on the risk over time and thereby maximize the therapeutic index.