Targeting Ovarian Tumor Associated Myeloid Cells with Nanoparticles Therapeutics

描述（由申请方提供）：小鼠研究表明，肿瘤相关髓样细胞是实体瘤的合理治疗靶点。卵巢癌的研究已经证明了大量的肿瘤相关的髓样细胞，称为血管白细胞（VLC）。VLC是高度免疫抑制和促血管生成的，分泌许多血管生成因子以促进肿瘤生长。靶向VLC的治疗有效地限制血管生成并抑制卵巢癌生长。不幸的是，动物模型中使用的治疗剂在人类中的使用有限，这是由于与缺乏特异性相关的显著副作用。因此，我们开发了新型细胞毒性纳米颗粒（G5-MTX-Nps），其对VLC具有高度特异性。由于它们的特异性，预计这些NP具有有限的副作用。因此，我们建议（1）测试G5-MTX-Nps作为新的抗VLC、抗血管生成治疗剂。我们将使用鼠卵巢肿瘤模型和使用新鲜分离的人VLC的人肿瘤模型进行这些研究。其他抗血管生成疗法，如抗VEGF抗体和VEGFR 2受体酪氨酸激酶抑制剂，已在卵巢癌中显示出临床活性。不幸的是，这些治疗的患者经历快速复发。有趣的是，据报道，抗VEGF靶向治疗的复发继发于VLC的肿瘤募集。因此，我们假设从卵巢癌微环境中消除VLC可以克服抗VEGF治疗的耐药性。因此，我们提出（2）确定靶向VLC的细胞毒性G5-MTX-Nps是否可以克服对抗血管生成治疗的抗性。我们将使用三种抗VEGF耐药模型进行这些研究：通过抗VEGF治疗进展的ID 8鼠卵巢肿瘤，表达VEGF水平增加的ID 8-VEGF肿瘤，以及招募大量肿瘤VLC的ID 8-VEGF-BDef肿瘤。此外，我们将使用新鲜分离的人肿瘤VLC的人肿瘤模型。最后，VLC与肿瘤血管系统紧密相关。有趣的是，癌症干细胞（CSC）也与肿瘤血管紧密相关，从肿瘤内皮细胞接收基本的生存线索。事实上，抗血管生成治疗可通过内皮提供的存活因子的这种损失导致CSC减少。我们有初步证据表明，VLC也为CSC提供了重要的生长信号。因此，我们假设抗VLC Np治疗将限制CSC生长。CSC生长的限制可能通过VLC产生的生长因子的损失和通过对肿瘤血管系统的抗血管生成作用而发生。因此，我们建议（3）确定G5-MTX-Nps治疗对卵巢CSC存活和增殖的影响，在体外和体内。我们将使用体外球体测定法对原代人卵巢CSC以及卵巢癌干细胞小鼠模型和人CSC异种移植物进行测试。

DESCRIPTION (provided by applicant): Murine studies indicate that tumor associated myeloid cells are a legitimate therapeutic target in solid tumors. Studies in ovarian cancer have demonstrated an abundant population of tumor associated myeloid cells termed vascular leukocytes (VLCs). VLCs are highly immunosuppressive and proangiogenic, secreting numerous angiogenic factors to promote tumor growth. Therapies targeting VLCs potently restrict angiogenesis and inhibit ovarian cancer growth. Unfortunately the therapeutics used in animal models have limited use in humans due to significant side effects associated with the lack of specificity. We have therefore developed novel cytotoxic nanoparticles (G5-MTX-Nps) which are highly specific for VLCs. Because of their specificity, these Nps are expected to have limited side-effects. We therefore propose (1) to test G5-MTX- Nps as a novel anti-VLC, anti-angiogenic therapeutic. We will perform these studies using both murine ovarian tumor models, and human tumor models using freshly isolated human VLCs. Other anti-angiogenic therapies, such as anti-VEGF antibodies and VEGFR2 receptor tyrosine kinase inhibitors, have demonstrated clinical activity in ovarian cancer. Unfortunately patients on these therapies experience rapid relapses. Interestingly, relapses to anti-VEGF targeted therapies have been reported to be secondary to tumor recruitment of VLCs. We therefore hypothesize that elimination of VLCs from the ovarian cancer microenvironment can overcome resistance to anti-VEGF therapy. We therefore propose (2) to determine if cytotoxic G5-MTX-Nps targeting VLCs can overcome resistance to antiangiogenic therapy. We will perform these studies using three models of anti-VEGF resistance: ID8 murine ovarian tumors which progress through anti-VEGF therapy, ID8-VEGF tumors which express increased levels of VEGF, and ID8-VEGF-BDef tumors which recruit large numbers of tumor VLCs. In addition, we will use human tumor models using freshly isolated human tumor VLCs. Finally, VLCs are tightly associated with tumor vasculature. Interestingly, cancer stem cells (CSC) are also tightly associated with the tumor vascular, receiving essential survival cues from the tumor endothelial cells. In fact anti-angiogenic therapy can lead to a reduction in CSC via this loss of endothelial provided survival factors. We have preliminary evidence that VLCs also provide important growth signals for CSC. We therefore hypothesize that anti-VLC Np therapy will restrict CSC growth. Restriction of CSC growth may occur both via the loss of VLC produced growth factors and via the anti-angiogenic effects on tumor vasculature. We therefore propose to (3) to determine the impact of G5-MTX-Nps therapy on ovarian CSC survival and proliferation, both in vitro and in vivo. We will test these using in vitro sphere assays with primary human ovarian CSC as well as in mouse models of ovarian cancer stem cells, and human CSC xenografts.