Novel use of PI3K inhibition to prevent recurrence of B-cell acute lymphoblastic leukemia

摘要 高达10%的急性淋巴母细胞瘤患者发生中枢神经系统(CNS)转移和复发 白血病(ALL)，尽管以中枢神经系统为导向，通过细胞毒化疗或颅脑脊髓照射进行预防。使用 由于没有统一有效的治疗方案，CNS复发的预后不到6个月。到目前为止， 所有侵袭中枢神经系统的分子机制一直知之甚少，阻止靶向药物 发展。我们的实验室最近发现了B-ALL细胞使用的一种以前未知的机制来进入 中枢神经系统。这种侵袭途径依赖于表面蛋白6整合素之间的关键分子相互作用 在所有原始细胞上表达，其受体层粘连蛋白在连接血管的基底膜上表达 从颅骨和脊椎骨髓到中枢神经系统软脑膜。我们进一步证明了B-All6 整合素的表达受PI3K信号的调节，而PI3K异构体在小鼠模型中的体内抑制作用 白血病可阻断中枢神经系统的转移。使用B-ALL的体外和体内小鼠模型，我们现在证明了治疗 通过PAN-PI3K异构体抑制剂，Copanlisib具有额外的治疗作用，包括细胞周期停滞和 所有爆炸的化学敏化。这些转化为减少中枢神经系统转移，减少全身疾病 白血病小鼠的负担和延长存活时间。基于这些数据，我们设计了一种新颖的窗口。 机会(WOO)临床试验，以表征在人类ALL中对PAN-PI3K抑制的分子反应。我们 我还设计了小鼠模型来研究PI3Ki对微小残留病持久性的影响 化疗后的多药耐药(MRD)是疾病复发的关键预后指标。在目前的研究提案中， 我们的目标是：1)对患者样本中的B-ALL细胞分子反应进行详细的相关性分析 和在我们的WOO试验中服用Copanlisib后，以及2)确定Copanlisib是否抑制PAN-PI3K 在我们的B-ALL临床前模型中，联合挽救化疗可以减少MRD。治疗性 PI3K抑制在ALL中的作用尚未确定；因此，从我们的WOO方案和 这项研究提案中描述的实验将为试验设计提供关键信息，以确定潜在的后续研究。 将科帕利西布纳入现有所有治疗方案的第二阶段研究。如果成功，我们的工作将 代表着针对所有人的中枢神经系统预防治疗的新突破，解决了一个重大未满足的领域 患者的临床需求。

ABSTRACT Central nervous system (CNS) metastasis and relapse occurs in up to 10% of patients with acute lymphoblastic leukemia (ALL), despite CNS-directed prophylaxis with cytotoxic chemotherapy or craniospinal irradiation. With no uniformly effective treatment options, CNS relapse carries a grim prognosis of less than 6 months. Until now, the molecular mechanism of ALL invasion into the CNS has been poorly understood, preventing targeted drug development. Our lab recently discovered a previously unknown mechanism used by B-ALL cells to enter the CNS. This invasion pathway is dependent on key molecular interactions between 6 integrin, a surface protein expressed on ALL blasts, and its receptor laminin, expressed on the basement membrane of vessels connecting the calvarial and vertebral bone marrow to the CNS leptomeninges. We further demonstrated that B-ALL 6 integrin expression is regulated by PI3K signaling, and that PI3K isoform inhibition in vivo in mouse models of leukemia blocks CNS metastasis. Using in vitro and in vivo mouse models of B-ALL, we now show that treatment with the pan-PI3K isoform inhibitor copanlisib has additional therapeutic effects including cell cycle arrest and chemosensitization of ALL blasts. These translate to decreased CNS metastasis, reduced systemic disease burden and prolonged survival in leukemic mice. Based on these data, we have designed a novel window-of- opportunity (WoO) clinical trial to characterize molecular responses to pan-PI3K inhibition in ALL in humans. We have also designed mouse models to study the impact of PI3Ki on the persistence of minimal residual disease (MRD) following chemotherapy, a key prognostic indicator of disease relapse. In the current research proposal, we aim to: 1) Perform detailed correlative analyses of B-ALL cell molecular responses in patient samples pre- and post-copanlisib dosing in our WoO trial, and 2) Determine whether pan-PI3K inhibition by copanlisib combined with salvage chemotherapy can decrease MRD in our preclinical models of B-ALL. The therapeutic role of PI3K inhibition in ALL has not yet been established; therefore, data gathered from our WoO protocol and the experiments described within this research proposal will critically inform trial design of a potential follow-on phase II study of copanlisib incorporated into existing ALL treatment regimens. If successful, our work will represent a novel breakthrough in CNS prophylactic therapy for ALL, addressing an area of substantial unmet clinical need for patients.