Interferon Activated Necroptosis as a New Therapeutic Avenue for Kidney Cancer

描述（由申请人提供）：晚期肾细胞癌 (RCC) 是一种致命的癌症，2013 年将在美国夺走超过 13,000 人的生命。目前，针对血管生成或营养感应途径的小分子抑制剂代表了该疾病的主要药物干预措施，但这些抑制剂只能延缓肿瘤进展，不能治愈。因此，肾细胞癌代表着重大的治疗挑战。与当前的小分子疗法不同，细胞因子干扰素-γ (IFN-γ) 在多项针对转移性肾细胞癌的 I/II 期试验中显示出提供持久缓解的潜力。然而，IFN-γ具有严重的毒副作用，削弱了其在临床使用的热情。这些副作用源于需要高剂量才能获得临床益处的两个主要限制：(1) RCC 细胞在很大程度上对 IFN-γ 的直接杀肿瘤作用有抵抗力，(2) IFN-γ 在循环中的半衰期非常短，因此在肿瘤中的生物利用度较差。在本提案中，我们概述了克服这两个缺点的途径。首先，我们确定了两种保护 RCC 细胞免受 IFN-γ 侵害的生存机制；在这两种机制都不存在的情况下，IFN-γ会在肾细胞癌细胞中引发一种新形式的程序性坏死（或坏死性凋亡）。其中一种机制 (NF-κB) 可以被 FDA 批准的小分子药物硼替佐米 (bortezomib) 禁用，硼替佐米 (bortezomib) 可以通过临床上容易实现的剂量的 IFN-γ 使 RCC（而非正常）细胞对坏死性凋亡敏感。其次，我们生成了新型 IFN-γ-抗体融合抗体，其 (1) 稳定血清中的 IFN-γ，以及 (2) 将 IFN-γ 靶向 RCC 细胞。我们预计这种 IFN-γ 融合物与硼替佐米的组合将发挥有效的杀肿瘤活性，同时大大降低全身毒性。为了实现三个目标，我们将 (1) 确定 IFN-γ 激活坏死性凋亡的机制，(2) 确定硼替佐米抑制途径中的其他靶标 通过确定 IFN-γ 如何激活 NF-κB，以及 (3) 在 RCC 小鼠模型中将天然 IFN-γ 和 IFN-γ 抗体融合物与硼替佐米结合起来。这项研究的结果直接适用于干扰素先前已显示出治疗潜力的几种人类癌症。

DESCRIPTION (provided by applicant): Advanced renal cell carcinoma (RCC) is an invariably fatal cancer that will claim over 13,000 lives in the US in 2013. Currently, small-molecule inhibitors that target angiogenesis or nutrient-sensing pathways represent the primary pharmacological interventions for this disease, but these inhibitors only delay tumor progression and are not curative. RCC therefore represents a significant therapeutic challenge. Unlike current small-molecule therapies, the cytokine interferon-gamma (IFN-γ) showed the potential to provide lasting remission in several phase I/II trials for metastatic RCC. IFN-γ, however, has severe toxic side-effects that have dampened enthusiasm for its use in the clinic. These side-effects arise from two major limitations that require high doses for clinical benefit: (1) RCC cell are largely resistant to IFN-γ's direct tumoricidal effects, and (2) IFN-γ has a very short half-lie in circulation, with consequently poor bioavailabity at the tumor. In this proposal, we outline avenues to overcome both these shortcomings. First, we have identified two survival mechanisms that protect RCC cells from IFN-γ; in the absence of either mechanism, IFN-γ triggers a novel form of programmed necrosis (or necroptosis) in RCC cells. One of these mechanisms (NF-κB) can be disabled by the small molecule FDA-approved agent bortezomib, and bortezomib sensitizes RCC - but not normal - cells to necroptotic death by doses of IFN-γ that are easily clinically achievable. Second, we have generated novel IFN-γ-antibody fusion antibodies that (1) stabilize IFN-γ in serum, and (2) target IFN-γ to RCC cells. We expect that the combination of such IFN-γ fusions and bortezomib will exert potent tumoricidal activity while greatly minimizing systemic toxicity. In three aims, we will (1) identify the mechanism by which IFN-γ activates necroptosis, (2) identify additional targets in the pathway inhibited by bortezomib by identifying how IFN-γ activates NF-κB, and (3) combine native IFN-γ and IFN-γ-antibody fusions with bortezomib in murine models of RCC. The findings from this study are directly applicable to several human cancers in which IFNs have previously shown therapeutic potential.