Preclinical Development of Novel Targeted Therapeutics Against Pediatric Sarcoma

1. IGF 1 R靶向剂：与Lee Helman博士合作，我们先前的结果揭示了癌症中IGF 1 R水平的高度变化（Cao等人，癌症研究68：8039-48，2008）显示癌细胞中IGF 1 R的水平与对抗IGF 1 R抗体的抗增殖应答之间的直接相关性。我们还确定了一个模型系统，其中IGF 1 R抗体选择性地诱导快速肿瘤细胞死亡在体外和体内。我们的结果说明了通过AKT和BclxL介导的抗IGF 1 R诱导的癌细胞死亡的机制（Mayeenuddin等人，Oncogene 29：6367-6377，2010）。与Raffit哈桑博士合作，发现IGF 1 R抗体在间皮瘤中是有活性的，与IGF-1 R位点/细胞相关（Kalra et al.，Int J Cancer 131：2143-52，2012）。与Lee Helman博士合作，我们最近的数据显示IFG 1 R升高与横纹肌肉瘤的预后较差相关，对IGF 1 R靶向抗体的抗性与横纹肌肉瘤中IGFBP 2的下调相关（Kang et al.，Oncogene，33：5697-705，2014）。2.死亡受体靶向药物为了鉴定对肉瘤具有选择性活性的新型药物和预测反应的生物标志物，我们研究了儿科癌症中的死亡受体靶向抗体。在与Genentech的合作中，我们发现DR 5，而不是DR 4，在所有横纹肌肉瘤（RMS）细胞的表面持续高水平。DR 5抗体drozitumab在体外对大多数RMS细胞系有效。我们观察到半胱天冬酶-8的表达可预测对drozitumab的反应。更重要的是，半胱天冬酶-8的催化活性对于介导对drozitumab的敏感性是必要的，也是足够的。我们的结果进一步显示Drozitumab在体外和体内有效，并且可以提供RMS的长期控制（Kang Clin. Cancer Res.2011）。我们最近的研究集中在与安进公司的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对体外人DR 5激动剂抗体conatumumab的敏感性，该抗体诱导caspase-8的快速活化和细胞凋亡。进一步的分析揭示了对conatumumab的敏感性与caspase-8表达的相关性，其催化活性对于赋予这种敏感性是必要的和足够的。在体内，conatumumab对EWS细胞系和具有较高半胱天冬酶-8表达的患者来源的异种移植物都有活性，但对另一种具有较低半胱天冬酶-8表达的患者来源的异种移植物无效。这些研究表明，conatumumab作为针对尤文肉瘤的治疗剂的潜力，并且半胱天冬酶-8表达可以作为预测性生物标志物（Kang等人，Brit J of Cancer 2015）。3. SLFN 11作为尤文肉瘤药物反应的生物标志物在与Yves Pompeo博士的合作中，我们表明SLFN 11是EWS-FLI 1癌基因的直接靶点，并有助于尤文肉瘤中top-1抑制剂的药物反应（Tang et al.，Clin Cancer Res. 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 (Kang et al, Brit J of Cancer 2015). 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).