IHC Test for BRCA1 Hereditary Ovarian Cancer

描述（由申请人提供）：这是一项快速通道提案，旨在开发BRCA1遗传性卵巢癌的基于组织的基因检测。10%的未选择的美国卵巢癌是BRCA1基因突变的BRCA1遗传性癌症。了解哪些卵巢癌患者患有BRCA1遗传性卵巢癌是很重要的，因为BRCA1患者患乳腺癌的风险增加，其突变亲属患乳腺癌和卵巢癌的风险增加。如果可以进行广泛的基因筛查，这些后续癌症将被早期发现或预防。最近的数据表明，BRCA遗传性癌症对顺铂和PARP抑制剂等靶向治疗有反应。我们开发了一种基于抗体的组织截断方法来识别BRCA1遗传性癌症，并在一项初步研究中能够正确识别5/5 BRCA1遗传性癌症和20/200散发性癌症。该方法通过免疫组织化学（IHC）显示n端存在而c端缺失，从而可视化蛋白质截断。该产品（测试）将是一种基于抗体的免疫组化诊断试剂盒，用于癌症组织样本，医院实验室将使用它来识别遗传性癌症。我们已经成功开发并发表了一种类似的IHC方法，用于识别BRCA2遗传性癌症，灵敏度为95%，特异性为98%。I期提案的里程碑是：1)确定具有n端和c端BRCA1抗体的IHC的最佳组织制备方案。2)建立卵巢组织n端和c端BRCA1免疫染色定量评分系统，检测内变异性为15%，检测间变异性为20%或以下。3)证明蛋白质截断的c端与n端比值（BRCA1截断比）可以区分20例遗传性BRCA1卵巢癌和50例散发性卵巢癌，敏感性和特异性大于90%（比较不同评分系统）。完成这些里程碑后，我们将追求以下II期里程碑：里程碑1a：确定已知BRCA2突变的20例卵巢癌患者中BRCA1截断率的特异性。里程碑1b：在10例报告有BRCA1多态性/错义变异体的卵巢癌患者中确定截断比的特异性。里程碑2：在300例卵巢癌样本（样本量为30例BRCA1遗传性癌症）的临床试验中，确定BRCA1截断检测是否可以达到90%的灵敏度和特异性。乳腺癌/卵巢癌基因检测的医学应用是一个成熟的市场，因为Myriad Genetics每年在DNA测序上的总收入为1.5亿美元。

DESCRIPTION (provided by applicant): This is a Fast-Track proposal to develop a tissue-based genetic test for BRCA1 hereditary ovarian cancer. Ten percent of unselected US ovarian cancers are BRCA1 hereditary cancers with truncating mutations in the BRCA1 gene. It is important to know which ovarian cancer patients have BRCA1 hereditary ovarian cancer because BRCA1 patients have an increased risk of breast cancer and their relatives with mutations have an increased risk of breast and ovarian cancer. These subsequent cancers would be discovered early or prevented if widespread genetic screening was available and recent data indicates that BRCA hereditary cancers respond to targeted therapies such as cis-platinum and PARP inhibitors. We have developed an antibody-based tissue truncation method to identify BRCA1 hereditary cancers and were able to correctly identify 5/5 BRCA1 hereditary cancers and 20/200 sporadic cancers in a pilot study. This approach visualizes protein truncation by showing with immunohistochemistry (IHC) that the N-terminus is present but the C-terminus is absent. The product (test) will be an antibody-based IHC diagnostic kit for cancer tissue samples which hospital labs will use to identify hereditary cancers. We have already successful developed and published a similar IHC method to identify BRCA2 hereditary cancers with sensitivity of 95% and specificity of 98%.The milestones for the Phase I proposal are: 1) Determine optimal tissue preparation protocols for IHC with both N-terminal and C-terminal BRCA1 antibodies. 2) Develop a quantitative scoring system for N-terminal and C-Terminal BRCA1 immunostaining on ovarian tissues with intra-assay variability of 15% and inter-assay variability of 20% or less. 3) Demonstrate that a C-terminal to N-terminal ratio for protein truncation (BRCA1 Truncation Ratio) can distinguish 20 hereditary BRCA1 ovarian cancers from 50 sporadic ovarian cases with greater than 90% sensitivity and specificity (comparing different scoring systems). Upon completion of these milestones we would pursue the following Phase II milestones: Milestone 1a: Determine the specificity of the BRCA1 truncation ratio in 20 ovarian cancers in patients known to have BRCA2 mutations. Milestone 1b: Determine the specificity of the truncation ratio in 10 ovarian cancers in patients reported to have polymorphisms/missense variants of BRCA1. Milestone 2: Determine if the BRCA1 truncation test can achieve 90% sensitivity and specificity in a clinical trial of 300 ovarian cancer samples (sample size to provide 30 BRCA1 hereditary cancers). The medical application of breast/ovarian cancer genetic testing is a proven market since Myriad Genetics annually grosses $150 million on DNA sequencing. PUBLIC HEALTH RELEVANCE: Successful completion of this Fast-track research will establish a new tissue- based genetic test for BRCA1 hereditary ovarian cancer based on an IHC method to visualize protein truncation. This simpler more widely applicable approach will help predict appropriate therapy for patients with BRCA1 hereditary cancer and identify many more families with hereditary breast and ovarian cancer and consequently help patients and their relatives by identifying individuals likely to develop subsequent breast or ovarian cancer which might be prevented by tamoxifen and/or screening.