Establishing Drosophila melanogaster as part of the pre-clinical pipeline for anti-metastatic cancer drug discovery

在英国，每两分钟就有人被诊断出患有癌症。目前，这导致英国每年约有16.4万人死于癌症，主要是癌症转移。虽然某些类型的转移性癌症可以用现有的治疗方法治愈，但大多数都不能，目前的治疗旨在简单地阻止或减缓癌症的生长，或缓解由癌症引起的症状。这意味着迫切需要新的治疗方法。创新的新药物筛选正在体外开发，这在抗转移性癌症药物发现方面非常有希望。Berx和Goossens实验室已经开发出一种这样的筛选方法，其目标是寻找能够阻断一般细胞过程的化合物，这种过程被称为上皮细胞向间质细胞转化（EMT）。虽然EMT在正常的、受调节的发育过程中是必需的，但当它在癌细胞中被激活时，它可以促进细胞逃逸到体内，并驱动化疗耐药性。考虑到许多突变可能导致癌症转移，并且这些突变在个体之间可能存在很大差异，我们的方法是找到阻断EMT的化合物，而不管上游触发因素如何。Berx和Goossens设计了一种复杂的高通量体外筛选方法，旨在发现这些化合物，该方法已经产生了许多非常令人兴奋的成果。虽然这些化合物和药物库筛选可以在培养皿中的细胞上完成，但不幸的是，癌症的扩散和转移是一个复杂的多步骤过程，只能在整个动物身上完全模拟。因此，在对人类患者测试新化合物之前，在整个动物身上进行临床前研究对于测试它们在这种情况下的作用至关重要。因此，在体外筛选之后，Berx/Goossens实验室的下一步，就像在许多其他研究中一样，是在小鼠模型中测试他们鉴定的抗emt化合物的功效。由于毒性、稳定性或被人体吸收的能力等问题，许多在体外鉴定的化合物在小鼠身上测试时往往失败。在这里，我们建议不要直接从体外研究转移到老鼠身上，而是引入一个步骤，首先在黑腹果蝇身上测试化合物，作为第一个港口，看看这些化合物是否会在整个动物环境中起作用。我们假设建立果蝇作为体内功效的第一个测试具有巨大的潜力，可以消除假阳性，以及体内有毒或根本无法被人体吸收的化合物。虽然在过去，这可能受到缺乏苍蝇模型的限制，在这些模型中，细胞可以从开始迁移到在成年生物体中播种和生长，但我们最近克服了这个长期存在的限制。我们最近建立了转移性结直肠癌的果蝇模型，以及量化原发性肿瘤负荷、循环肿瘤细胞和宏观继发性转移形成的稳健、敏感的测定方法。我们建议将该模型引入Berx/Goossens抗emt药物发现管道，作为全动物试验的第一步。虽然在临床试验之前，化合物仍需要在更接近人类的哺乳动物模型中进行测试，但我们实验室的初步结果表明，只有在果蝇身上表现出强大功效的化合物才能向前推进，这将导致小鼠的使用至少减少75%。虽然该提案的重点是将果蝇作为抗转移性癌症药物发现管道中的一个步骤，但我们期望进一步模型的开发，并证明这种果蝇-小鼠实验室合作的力量，将导致这种方法的广泛采用，并在减少药物发现管道中使用的小鼠数量方面产生重大影响。

Every two minutes in the UK someone is diagnosed with cancer. Currently this leads to around 164,000 cancer deaths in the UK every year, mainly from metastasis. Although some types of metastatic cancer can be cured with existing treatments, most cannot, and current treatments are aimed at simply stopping or slowing the growth of the cancer, or to relieve symptoms caused by it. This means that there is an urgent need for new therapies.Innovative new drug screens are being developed in vitro, that are very promising in terms of anti-metastatic cancer drug discovery. One such screen has been developed by the Berx and Goossens labs, which is targeted at finding compounds that block a general cell process called the epithelial-to-mesenchymal transition (EMT). While EMT is required during normal, regulated development, when activated in cancer cells it can facilitate the escape of cells into the body, as well as drive chemoresistance. Given that many mutations can contribute to cancer metastasis, and that these can differ greatly between individuals, our approach is to find compounds that block EMT regardless of the upstream triggers. Berx and Goossens have designed a sophisticated high-throughput in vitro screen aimed at finding such compounds, that has already produced a number of very exciting hits.While these compound and drug library screens can be done on cells in a dish, unfortunately cancer spreading and metastasis is a complex multi-step process that can only be fully mimicked in a whole animal. Therefore, before moving on to testing new compounds on human patients, preclinical studies in whole animals are of utmost important to test that they work in this context. The next step in the Berx/Goossens labs after in vitro screens, as in many other studies, is therefore to test the efficacy of their identified anti-EMT compounds in mouse models. Many compounds identified in vitro often fail when tested on mice, due to issues such as toxicity, stability or ability to be absorbed into the body. Here we propose to that instead of moving directly from in vitro studies - to mice, to introduce a step where compounds are first tested on Drosophila melanogaster, as a first port of call to see if the compounds will work in a whole animal context. We hypothesise that establishing Drosophila as the first test for in vivo efficacy has huge potential to eliminate false positives, along with compounds that are toxic in vivo or simply cannot be absorbed into the body. While in the past, this would have been limited by a lack of fly models where cells can be followed from initiation of migration - to seeding and growth in adult organisms, we recently overcame this longstanding limitation. We have recently generated a Drosophila model for metastatic colorectal cancer, as well as robust, sensitive assays to quantify primary tumour burden, circulating tumour cells and formation of macroscopic secondary metastases. We propose to introduce this model into the Berx/Goossens anti-EMT drug discovery pipeline, as the first step for whole animal testing. While compounds will still need to be tested in a mammalian model closer to humans before clinical trials, by only moving forward with compounds that have demonstrated robust efficacy in Drosophila, preliminary results from our labs suggest that this will lead to at least 75% drop in the use of mice. While this proposal is focused towards establishing Drosophila as a step in the pipeline for anti-metastatic cancer drug discovery, we expect that the development of further models, and demonstrating the power of such a Drosophila-mouse lab collaboration, will lead to a wide uptake of this approach, and have a great impact in reducing the numbers of mice used in the drug discovery pipeline.