Src inhibition in Colorectal Cancer

描述(申请人提供)：奥沙利铂是转移性结直肠癌化疗方案中的一种有效药物，但大多数患者要么对5-FU和奥沙利铂(FOLFOX)联合治疗无效，要么随后产生耐药性。一个可能导致奥沙利铂耐药的候选分子是蛋白酪氨酸激酶，它的活性在结直肠癌进展过程中增加，在转移性疾病中最高。我们的初步研究表明，在体外和体内奥沙利铂处理后，结肠癌细胞系中的Src被激活。我们已经证明，siRNA对Src的抑制增加了对奥沙利铂的敏感性。同样，口服酪氨酸激酶抑制剂达沙替尼对Src的药物抑制在体外与奥沙利铂具有协同作用，并在原位小鼠模型中显示至少超相加减少肿瘤大小。这些发现导致以下假设将在本方案中得到验证：奥沙利铂治疗引起的SRC激活是一种促进生存的机制，因此抑制Src将改善奥沙利铂对转移性结直肠癌的细胞毒性。具体目的1是通过分子方法确定结构性的Src激活是否足以在细胞培养和原位裸鼠结直肠癌肝转移模型中诱导奥沙利铂耐药，以建立Src活性不受调控的结直肠肿瘤细胞系。这些研究将使用具有点突变的转基因Src，使Src具有结构性活性，从而可以评估奥沙利铂的敏感性和达沙替尼治疗的后续影响。具体目的2是确定奥沙利铂治疗后肝转移癌患者行肝转移切除术后Src激活的频率，以证明这些临床前发现的临床相关性。具体目的3旨在评价达沙替尼联合FOLFOX+西妥昔单抗治疗转移性结直肠癌的安全性、初步疗效和药效学。这项由研究人员发起的研究，包括广泛的相关研究，证明了在肿瘤中对Src和Src靶点的抑制。具体目的4进一步评估该方案在贝叶斯适应性随机、安慰剂对照的FOLFOX+西妥昔单抗+/-达沙替尼的II期研究中的疗效，同时评估Src抑制的生物标记物。成功的实施将提高目前转移性结直肠癌化疗的有效性，从而改善转移性结直肠癌人群的预后。

DESCRIPTION (provided by applicant): Oxaliplatin is an active agent in metastatic colorectal cancer regimens, but most patients either fail to respond to 5-FU and oxaliplatin (FOLFOX) combinations or subsequently develop resistance. A candidate molecule that might contribute to oxaliplatin resistance is the protein tyrosine kinase, Src, the activity of which is increased during colorectal tumor progression and highest in metastatic disease. Our preliminary studies demonstrate that Src is activated in colon cancer cell lines after oxaliplatin treatment in vitro and in vivo. We have shown that inhibition of Src by siRNA increases sensitivity to oxaliplatin. Likewise, pharmacologic inhibition of Src with dasatinib, an oral tyrosine kinase inhibitor, is synergistic with oxaliplatin in vitro and demonstrates at least supra-additive reductions in tumor size in an orthotopic murine model. These findings lead to the following hypothesis to be tested in this proposal: Src activation resulting from oxaliplatin treatment is a pro-survival mechanism and inhibition of Src will therefore improve oxaliplatin cytotoxicity in metastatic colorectal cancer. Specific aim 1 is to determine if constitutive Src activation is sufficient to induce oxaliplatin resistance in both cell cultures and an orthotopic nude mouse model of colorectal liver metastases by molecular approaches to develop colorectal tumor cell lines in which Src activity cannot be regulated. These studies will use transfected Src with a point mutation rendering Src constitutively active, thereby allowing evaluation of oxaliplatin sensitivity and the subsequent impact of dasatinib therapy. Specific aim 2 is to determine the frequency of Src activation in liver metastases after oxaliplatin treatment in colorectal patients undergoing liver metastasectomy in order to demonstrate the clinical relevance of these preclinical findings. Specific aim 3 is designed to evaluate the safety, preliminary efficacy, and pharmacodynamics of the combination of dasatinib and FOLFOX + cetuximab in patients with metastatic colorectal cancer. This investigator-initiated study, to which we have recently initiated accrual, includes extensive correlative studies to demonstrate inhibition of Src and Src targets in the tumor. Specific aim 4 further evaluates the efficacy of this regimen in a Bayesian adaptively randomized, placebo-controlled phase II study of FOLFOX + cetuximab +/- dasatinib, with concurrent evaluation of a biomarker of Src inhibition. Successful implementation will improve the effectiveness of current chemotherapies for metastatic colorectal cancer, resulting in improved outcomes for the metastatic colorectal cancer population.