Development of sEphB4-HSA as Novel Therapeutic in Cancer

描述(申请人提供)：在胚胎发育过程中，EphB4和EPhinB2都是新形成的血管成熟所必需的。它是VEGFR2/3激活所必需的，在肿瘤血管中表达上调，其缺失导致肿瘤血管生成受阻，抑制肿瘤生长。另一方面，EphB4在许多上皮性癌症中被高度诱导，并作为一种肿瘤生存因子。表达在肿瘤细胞上的EphB4还与肿瘤血管上的EPhinB2相互作用，促进肿瘤细胞存活和肿瘤血管生成。我们开发了一种EphB4-EPhinB2抑制剂--EphB4与人血清白蛋白融合的胞外片段(sEphB4-HSA)。在SBIR一期项目中，我们已经在许多异种移植瘤和自发性肿瘤模型中证明了sEphB4-HSA抑制肿瘤生长和导致肿瘤消退，并且与化疗药物联合使用具有相加/协同作用。特别是，sEphB4-HSA在异种移植瘤和遗传性肿瘤模型中对Kras突变驱动的肿瘤的消退非常有效。我们已经生产了GMP质量的sEphB4-HSA，并在小鼠和猴子身上进行了GLP药代动力学(PK)和毒理学研究。IND的申请已经获得批准，sEphB4-HSA目前正在进行人类I期临床试验。首先，累积了三个剂量水平，没有观察到剂量限制性毒性。所有患者均未出现三级或四级毒性反应。也有临床受益的迹象。1名最低剂量(2.5 mg/kg)的患者在开始治疗后的4个月内病情稳定。包括第二剂量水平(5 mg/kg)的KRAS肺腺癌在内的三名患者已经接受治疗3-4个月，所有患者都有稳定的疾病，两名患者显示出肿瘤消退的迹象。因此，我们将生产大量(1.7公斤)的sEphB4-HSA，用于即将到来的Kras突变肺癌和胰腺癌的人类第二阶段临床试验。为了确定治疗方案，我们将在Kras基因突变小鼠模型中进行疗效研究(同时存在或不存在P53突变)。我们将测试sEphB4-HSA作为单一药物，也将与化疗药物联合使用。最后，我们将在不同的时间点采集患者的血液，并应用新技术分离循环中的肿瘤细胞，并分析sEphB4-HSA靶标的表达。我们还将分析抗血管生成治疗的两个已知生物标志物--血管内皮生长因子和可溶性血管内皮生长因子-2的循环水平。这些结果将指导我们确定sEphB4-HSA的药效学生物标志物，这将在临床评估患者的反应中非常有用。

DESCRIPTION (provided by applicant): During embryonic development, EphB4 and EphrinB2 are both critically required for maturation of newly forming blood vessels. EphrinB2 and is critically required for activation of VEGFR2/3. EphrinB2 is up-regulated in tumor vasculature and loss of EphrinB2 led to arrested tumor angiogenesis and inhibited tumor growth. On the other hand, EphB4 is highly induced in many epithelial cancers and serves as a tumor survival factor. EphB4 expressed on tumor cells also interacts with EphrinB2 on tumor vessels and promotes both the tumor cell survival and the tumor angiogenesis. We have developed an EphB4-EphrinB2 inhibitor - the extracellular fragment of EphB4 fused with human serum albumin (sEphB4-HSA). In SBIR phase I project, we have shown that sEphB4-HSA inhibits tumor growth and causes tumor regression in many xenograft and spontaneous tumor models, and combination with chemotherapy agents has additive/synergistic effect. Particularly sEphB4-HSA is highly effective in regressing Kras mutant driven tumors in xenograft and genetic tumor models. We have produced GMP quality sEphB4-HSA and performed GLP pharmacokinetics (PK) and toxicology studies in mice and monkeys. The IND application has been approved and sEphB4-HSA now is in human phase I clinical trial. First three dose levels have been accrued and no dose limiting toxicity has been observed. None of the patients have experienced grade three or grade four toxicity. There are also signs of clinical benefit. One patient at the lowest dose (2.5mg/kg) has had stable disease at 4 months since the initiation of the treatment. Three patients including a kras lung adenocarcinoma at the second dose level (5mg/kg) have stayed on therapy for 3-4 months and all have had stable diseases and two have shown signs of tumor regression. Therefore, we will manufacture large quantity (1.7 kg) of sEphB4-HSA for the coming human Phase II clinical trials in Kras mutant lung and pancreatic cancers. To determine the treatment regimens, we will conduct efficacy studies in genetic Kras mutant mouse models (with or without concurrent p53 mutation). We will test sEphB4-HSA as a single agent and also combined with chemotherapy agents. Finally we will collect blood from patients at various time points and apply novel technology to isolate circulating tumor cells and analyze the expression of sEphB4-HSA targets. We will also analyze the circulating levels of VEGF and soluble VEGFR2, two known biomarkers of anti-angiogenesis therapies. These results will guide us to identify the pharmacodynamic biomarker of sEphB4-HSA, which will be very useful in the evaluation of patient responses in the clinic.