Preclinical Development of Novel Targeted Therapeutics Against Pediatric Sarcoma

1.IGF1R靶向药物：我们之前与Lee Helman博士合作的结果显示，在癌症中IGF1R水平的高度变异(Cao等人，癌症研究，68：8039-48,2008)表明，癌细胞中的IGF1R水平与抗IGF1R抗体的抗增殖反应之间存在直接关联。我们还确定了IGF1R抗体选择性地在体内外诱导肿瘤细胞快速死亡的模型系统。我们的结果阐明了通过AKT和BclxL介导的抗IGF1R诱导癌细胞死亡的机制(Mayeenuddin等，Oncogene 29：6367-6377,2010)。与Raffit Hassan博士合作，发现IGF1R抗体在间皮瘤中活跃与IGF-IR位点/细胞相关(Kalra等人，Int J Cancer 131：2143-52,2012)。与Lee Helman博士合作，我们最近的数据表明IFG1R升高与横纹肌肉瘤更差的预后相关。对IGF1R靶向抗体的抵抗与横纹肌肉瘤中IGFBP2的下调有关(Kang等，Oncogene，33：5697-705,2014)。2.死亡受体靶向药物为了寻找具有选择性抗肉瘤活性的新药物和预测反应的生物标志物，我们研究了一种死亡受体靶向抗体在儿童癌症中的应用。在与基因泰克的合作中，我们发现DR5，而不是DR4，持续存在于所有横纹肌肉瘤(RMS)细胞的高水平和表面。DR5抗体Drozitumab在体外对大多数RMS细胞株有一定的抑制作用。我们观察到，caspase-8的表达对Drozitumab的反应有预测作用。更重要的是，caspase-8的催化活性是调节Drozitumab敏感性的必要条件和充分条件。我们的结果进一步表明Drozitumab在体外和体内都是有效的，并可能提供对RMS(康宁)的长期控制。癌症研究报告，2011)。我们最近的研究集中在与安进公司合作的M-CRADA上，以评估他们针对尤文肉瘤的治疗性抗体Conatumumab。我们的临床前研究表明，它们在体外对人DR5激动型抗体Conatumumab具有敏感性，可诱导caspase-8的快速激活和细胞凋亡。进一步的分析揭示了对conatumumab的敏感性与caspase-8表达的相关性，caspase-8的催化活性是赋予这种敏感性的必要条件和充分条件。在体内，Conatumab对EWS细胞系和caspase-8表达较高的患者来源的异种移植瘤都有活性，但对另一种caspase-8表达较低的患者来源的异种移植瘤无效。这些研究表明，Conatumab作为治疗尤文氏肉瘤的药物的潜力和caspase-8的表达可能作为一个预测生物标记物。关于这项研究的手稿已被接受出版。3.SLFN11作为尤文肉瘤药物反应的生物标志物。在与Yves Pommier博士的合作中，我们表明SLFN11是EWS-FLI1癌基因的直接靶点，并有助于TOP-1抑制剂在尤文氏肉瘤中的药物反应(Tang等人，临床癌症研究，2015)。

1. IGF1R targeted agents: Working with Dr. Lee Helman, we previous results revealed a high degree of variation of IGF1R levels in cancers (Cao et al., Cancer Res. 68: 8039-48, 2008) showed a direct correlation between the levels of IGF1R in cancer cells and the anti-proliferative response to anti-IGF1R antibodies. We also have identified a model system in which IGF1R antibody selectively induced rapid tumor cell death in vitro and in vivo. Our results illustrate the mechanism of anti-IGF1R-induced cancer cell death mediated via AKT and BclxL (Mayeenuddin et al., Oncogene 29:6367-6377, 2010). Working with Dr. Raffit Hassan, it was found that IGF1R antibody was active in mesothelioma is correlated with IGF-IR sites/cell (Kalra et al., Int J Cancer 131:2143-52, 2012). Collaborating with Dr. Lee Helman, our recent data showed that elevated IFG1R was associated with worse prognosis of rhabdomyosarcoma the resistance to IGF1R targeted antibody was associated with the down regulation of IGFBP2 in rhabdomyosarcoma (Kang et al., Oncogene, 33:5697-705, 2014). 2. Death Receptor targeted agents To identify novel agents with selective activity against sarcoma and biomarkers predictive of responses, we investigated a death receptor targeted antibodies in pediatric cancers. In working with Genentech, We showed that DR5, but not DR4, persisted at high levels and on the surface of all rhabdomyosarcoma (RMS) cells. DR5 antibody drozitumab was effective in vitro against the majority of RMS cell lines. We observed that the caspase-8 expression is predictive to the response to drozitumab. More importantly, caspase-8 catalytic activity was both necessary and sufficient for mediating the sensitivity to drozitumab. We results further showed Drozitumab was effective in vitro and in vivo, and may provide long-term control of RMS (Kang Clin. Cancer Res. 2011). Our recent study has been focused on an M-CRADA with Amgen to evaluate their therapeutic antibody conatumumab against Ewing's sarcoma. Our preclinical study indicates their sensitivity to human DR5 agonist antibody conatumumab in vitro, which induces rapid activation of caspase-8 and apoptosis. Further analysis reveals the correlation of sensitivity to conatumumab with the expression of caspase-8, with its catalytic activity both necessary and sufficient to confer such sensitivity. In vivo, conatumumab is active against both a EWS cell line and a patient-derived xenograft with higher caspase-8 expression, but is not effective against another patient-derived xenograft with lower caspase-8 expression. These studies suggest the potential of conatumumab as a therapeutic agent against Ewing's sarcoma and caspase-8 expression may serve as a predictive biomarker. A manuscript on this study has been accepted for publication. 3. SLFN11 as a biomarker for drug response in Ewing's sarcoma. In working with Dr. Yves Pommier, we showed that SLFN11 is a direct target of EWS-FLI1 oncogene and contributes to drug response of top-1 inhibitors in Ewing's sarcoma (Tang et al., Clin Cancer Res. 2015).