Targeting Ovarian Tumor Associated Myeloid Cells with Nanoparticles Therapeutics

描述(申请人提供)：小鼠研究表明，肿瘤相关的髓系细胞是实体肿瘤的合法治疗靶点。对卵巢癌的研究表明，大量的肿瘤相关髓系细胞被称为血管白细胞(VLCs)。VLCs具有高度的免疫抑制和促血管生成作用，可分泌多种血管生成因子促进肿瘤生长。针对VLC的治疗有效地限制了血管生成，抑制了卵巢癌的生长。不幸的是，动物模型中使用的疗法在人类中的应用有限，因为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)，这种纳米颗粒对血管内皮细胞具有高度特异性。由于它们的特殊性，预计这些NPS的副作用有限。因此，我们建议(1)测试G5-MTX-NPS作为一种新型的抗VLC、抗血管生成治疗药物。我们将使用小鼠卵巢肿瘤模型和使用新鲜分离的人类VLCs的人类肿瘤模型来进行这些研究。其他抗血管生成疗法，如抗血管内皮生长因子抗体和血管内皮生长因子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，接受这些疗法的患者会迅速复发。有趣的是，据报道，抗血管内皮生长因子靶向治疗的复发是血管内皮细胞肿瘤募集的次要原因。因此，我们假设，清除卵巢癌微环境中的VLC可以克服抗血管内皮生长因子治疗的耐药性。因此，我们建议(2)确定靶向血管内皮细胞的细胞毒性G5-MTX-NPS是否能够克服抗血管生成治疗的耐药性。我们将使用三种抗血管内皮生长因子耐药模型进行这些研究：通过抗血管内皮生长因子治疗进展的ID8小鼠卵巢肿瘤，表达高水平血管内皮生长因子的ID8-VEGF肿瘤，以及募集大量肿瘤VLC的ID8-VEGF-BDef肿瘤。此外，我们将使用新鲜分离的人类肿瘤VLC来建立人类肿瘤模型。最后，VLC与肿瘤血管密切相关。有趣的是，肿瘤干细胞(CSC)也与肿瘤血管密切相关，从肿瘤内皮细胞接收必要的生存信号。事实上，抗血管生成治疗可以通过这种内皮细胞提供的生存因子的丧失而导致CSC的减少。我们有初步证据表明，VLCs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的生长。抑制CSC生长既可能是通过VLC产生的生长因子的丢失，也可能是通过对肿瘤血管的抗血管生成作用。因此，我们建议(3)确定G5-MTX-NPS治疗在体外和体内对卵巢CSC存活和增殖的影响。我们将使用原代人卵巢CSC以及卵巢癌干细胞和人类CSC异种移植的小鼠模型的体外球体分析来测试这些方法。

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.