Development of sEphB4-HSA as Novel Therapeutic in Cancer

描述（由申请人提供）：在胚胎发育期间，EphB 4和EphrinB 2都是新形成的血管成熟所必需的。EphrinB 2是激活VEGFR 2/3所必需的。EphrinB 2在肿瘤血管系统中上调，EphrinB 2的缺失导致肿瘤血管生成停滞并抑制肿瘤生长。另一方面，EphB 4在许多上皮癌中被高度诱导，并作为肿瘤存活因子。在肿瘤细胞上表达的EphB 4也与肿瘤血管上的EphrinB 2相互作用，并促进肿瘤细胞存活和肿瘤血管生成。我们已经开发了EphB 4-EphrinB 2抑制剂-EphB 4的细胞外片段与人血清白蛋白融合（sEphB 4-HSA）。在SBIR I期项目中，我们已经证明sEphB 4-HSA在许多异种移植和自发肿瘤模型中抑制肿瘤生长并导致肿瘤消退，并且与化疗药物组合具有累加/协同效应。特别地，sEphB 4-HSA在异种移植物和遗传肿瘤模型中高度有效地消退Kras突变体驱动的肿瘤。我们生产了GMP质量的sEphB 4-HSA，并在小鼠和猴中进行了GLP药代动力学（PK）和毒理学研究。IND申请已获批准，sEphB 4-HSA已进入人体I期临床试验。前三个剂量水平已累积，未观察到剂量限制性毒性。所有患者均未出现3级或4级毒性。也有临床受益的迹象。最低剂量组（2.5 mg/kg）的1例患者在治疗开始后4个月时病情稳定。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持续治疗3-4个月，并且所有患者都具有稳定的疾病，并且两名患者显示出肿瘤消退的迹象。因此，我们将生产大量（1.7kg）sEphB 4-HSA用于即将进行的Kras突变型肺癌和胰腺癌的人类II期临床试验。为了确定治疗方案，我们将在遗传Kras突变小鼠模型（伴或不伴p53突变）中进行疗效研究。我们将测试sEphB 4-HSA作为单一药剂以及与化疗剂组合。最后，我们将在不同时间点收集患者的血液，并应用新技术分离循环肿瘤细胞，分析sEphB 4-HSA靶点的表达。我们还将分析VEGF和可溶性VEGFR 2的循环水平，这两种已知的抗血管生成疗法的生物标志物。这些结果将指导我们确定sEphB 4-HSA的药效学生物标志物，这将是非常有用的，在临床上评估患者的反应。

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.