Ex vivo purging strategy for treatment of multiple myeloma

描述(申请人提供)：本申请的最终目标是开发一种新的使用兔特异性痘病毒粘液瘤病毒(MYXV)的体外净化方法，以改善多发性骨髓瘤(MM)的临床疗效。MM是一种克隆性浆细胞恶性肿瘤，到目前为止基本上抵抗了所有的治疗策略。目前，多发性骨髓瘤患者的治疗标准是先进行大剂量化疗，然后进行自体干细胞移植。虽然ASCT通常可以增加符合条件的患者的无病间隔时间，但这种疾病通常会复发。这种癌症复发是由来自两个来源中的一个或两个来源的细胞介导的：残留在患者造血系统中的抵抗化疗的骨髓瘤细胞，和/或污染自体干细胞移植样本的残留骨髓瘤细胞。最近，当MYXV被用于对原发MM患者ASTC样本进行预处理时，被发现能够删除所有残留的MM细胞，同时完全保留在异种移植动物模型中重建受体免疫系统所需的正常人类干细胞。MYXV对人类或小鼠完全没有致病性，但对多种人类癌细胞具有天然的趋向性，正被开发为一种用于治疗各种癌症的病毒溶瘤剂。我们认为，移植前对ASCT移植物进行体外MYXV治疗将降低MM病的复发率。在这一第一阶段的STTR应用中，MYXV被提出了三个具体目标，以促进MYXV作为一种安全的治疗药物在多发性骨髓瘤患者ASCT前用于体外清除癌细胞：(1)通过体外测试MYXV与原代人类移植骨髓细胞和外周血单核细胞的相互作用来评估安全性。(2)在合适的动物模型中评估用于临床开发的特定MYXV载体克隆和净化方法学。这一目标的目的是复制将向FDA建议用于人类I期临床试验的准确的临床体外净化策略。(3)优化MYXV体外治疗人骨髓或外周血单核细胞的程序，以提供支持未来人类临床安全性试验所需的临床前数据。需要优化的各种因素包括确保产品稳定性和与体外治疗相容的MYXV菌种配方、孵育缓冲液和条件、移植中MXYV颗粒或感染单位与有核细胞总数的比率、体外孵育过程中病毒和细胞的浓度，以及MYXV的最小和最大有效和无作用剂量。

DESCRIPTION (provided by applicant): The ultimate goal of this application is to develop a novel ex vivo purging method using myxoma virus (MYXV), a rabbit-specific poxvirus, to improve the clinical outcomes in treatment of multiple myeloma (MM). MM is a clonal plasma cell malignancy that has to date resisted essentially all therapeutic strategies. Currently, the standard of care for patients with MM is treatment with high-dose chemotherapy followed by autologous stem cell transplantation (ASTC). Although ASCT can often increase the disease-free interval for eligible patients, the disease generally relapses. This cancer relapse is mediated by cells derived from one or both of two sources: myeloma cells remaining within patient's hematopoietic system that resist the chemotherapy, and/or residual myeloma cells that contaminate the autologous stem cell graft sample. Recently, MYXV, when used to pre-treat primary MM patient ASTC samples, was found to be able to delete all residual MM cells while completely sparing the normal human stem cells needed to reconstitute the recipient immune system in a xenotransplantation animal model. MYXV is completely nonpathogenic to humans or mice, but has a natural tropism for a variety of human cancer cells and is being developed as a viral oncolytic agent for the treatment of a variety of cancers. We propose that ex vivo MYXV treatment of ASCT grafts prior to transplant will reduce MM disease relapse rates. In this Phase I STTR application, three specific aims are proposed to progress the development of MYXV as a safe therapeutic drug for the ex vivo purging of cancer cells to be used before ASCT in MM patients: (1) Evaluate safety by in vitro testing the interaction of MYXV with primary human transplant bone marrow cells and peripheral blood mononuclear cells. (2) To assess the specific MYXV vector clone chosen for clinical development and the purging methodology in an appropriate animal model. The intention of this Aim is to replicate in toto the exact clinical ex vivo purging strategy that will be proposed to the FDA for the human Phase I clinical trial. (3) Optimize the procedures for the ex vivo treatment of human bone marrow or peripheral blood mononuclear cells with MYXV to provide preclinical data required to support a future human clinical safety trial. The various factors to be optimized include the formulation for the MYXV stocks that ensures product stability and is compatibility with ex vivo treatment, the incubation buffer and conditions, the ratio of MXYV particles or infectious units to total nucleated cells in the transplant, the concentration of virus and cells during ex vivo incubation, and the minimum and maximally effective and no- effect doses of MYXV.