Defining the novel cancer testis antigen HSPA1L as immunotherapeutic target in AML

科学摘要 急性髓系白血病(AML)包括一组遗传和临床上不同的 侵袭性血液系统恶性肿瘤。尽管在AML的分子特征方面取得了进展，但大多数 患者将复发并死于他们的疾病，这表明迫切需要新的治疗方法。 近年来，基于抗体的治疗方法已成为白血病治疗的有效工具，但仍需要 新的目标。我们使用来自不同白血病亚型的原始白血病细胞的蛋白质组学研究发现 一个可能的治疗靶点HSPA1L，表达于AML和其他血液病的细胞表面 恶性肿瘤，但保留男性生殖系统以外的正常组织。我们验证了这一表达 通过流式细胞术和共聚焦分析打靶。我们的假设是免疫治疗接近靶向 表面蛋白HSPA1L的特定表位可以选择性地消除靶向表达的AML 避免免疫相关的不良反应。重要的是，我们已经产生了单抗 抗HSPA1L单抗，经ELISA筛选阳性克隆，验证AML细胞表面靶向结合 细胞。在这个方案中，我们将描述HSPA1L在AML和AML干/祖细胞中的表达模式 细胞；并通过检测抗体，将首次生产的单抗用于治疗应用 单独、抗体-药物结合物或作为免疫参与的体外和体内靶向耗竭效应功能 活体白血病模型。 在目标1中，我们将对选定的候选抗体进行表征，探索单独使用它们的可行性，以 触发补体依赖性细胞毒(CDC)或使效应细胞(如NK和巨噬细胞)参与 触发抗体依赖细胞的细胞毒性或吞噬作用(ADCC或ADCP)；或作为抗体-药物结合物 (ADC)通过将单抗与金黄色葡萄糖素偶联。HSPA1L在AML及AML干/祖细胞中的表达 细胞和在正常骨髓细胞和造血干细胞将被研究。 在目标2中，我们将测试所选的具有或不具有偶联的先导HSPA1L单抗作为ADC的有效性 使用SCID小鼠的生物发光标记的AML细胞系模型和患者来源的异种移植(PDX)中的活体 NSG小鼠AML模型的建立。 我们已经组建了一支由经验丰富的具有深厚单抗背景的调查人员组成的多方面团队 成人和成人新药的产生和测试、蛋白质组学和靶点发现、临床前评估 儿童白血病的体外和体内模型，成人和儿童急性白血病的临床翻译。如果 成功，这一多研究者项目将产生新的抗体，为未来的临床开发的目标- 表达白血病，将在临床试验中单独测试或与标准化疗联合测试。

SCIENTIFIC ABSTRACT Acute myeloid leukemia (AML) comprises a genetically and clinically heterogeneous group of aggressive hematological malignancies. Despite advances in molecular characterization of AML, the majority of patients will relapse and die of their disease, indicating the urgent need for novel therapeutic approaches. Recently, antibody-based therapeutics have emerged as an effective tool in leukemia therapy but still in need of novel targets. Our proteomic studies using blast leukemia cells from different leukemia subtypes, have identified a putative therapeutic target HSPA1L, as being expressed on the cell surface of AML and other hematologic malignancies, but sparing normal tissues except for male reproductive system. We validated expression of this target by flow cytometry and confocal analyses. Our hypothesis is that immune therapy approaches targeting specific epitopes of the surface protein HSPA1L can selectively eliminate target-expressing AML while avoiding immune-related adverse effects. Importantly, we have already generated monoclonal antibodies (MAbs) against HSPA1L, selected positive clones by ELISA and validated cell surface target binding in AML cells. In this proposal, we will characterize expression patterns of HSPA1L in AML and AML stem/progenitor cells; and utilize first-time produced monoclonal antibodies for therapeutic applications, by testing antibodies alone, antibody-drug conjugates or as immune engaged targeted depletion effector function using in vitro and in vivo leukemia models. In Aim 1, we will characterize selected candidate antibodies exploring the feasibility of using them alone, to trigger complement depending cytotoxicity (CDC) or engage effector cells, such as NK and macrophages to trigger antibody dependent cell cytotoxicity or phagocytosis (ADCC or ADCP); or as antibody-drug conjugates (ADC) by conjugating MAbs to auristatin. The expression patterns of HSPA1L in AML, and AML stem/progenitor cells and in normal bone marrow cells and hematopoietic stem cells will be studied. In Aim 2, we will test the efficacy of the selected lead HSPA1L MAbs with or without conjugation as ADCs in vivo in bioluminescent-labeled AML cell line models using SCID mice, and in patient-derived xenograft (PDX) AML models in NSG mice. We have assembled a multi-faceted team of highly experienced investigators with deep background in MAbs generation and testing, proteomics and target discovery, pre-clinical assessment of novel agents in adult and pediatric leukemias in vitro and in vivo models, and clinical translation in adult and pediatric acute leukemias. If successful, this multi-investigator project will generate novel antibodies for future clinical development in target- expressing leukemias that will be tested in clinical trials, alone or in combination with standard chemotherapy.