Detection of circulating cell free tumour DNA in renal cancer patients for the prediction and detection of early disease recurrence

在过去的10年里，被诊断为肾癌(RCC)的患者数量一直在增加，占英国所有癌症的4%。透明细胞肾癌(CcRCC)是主要的亚型，约占所有病例的75%。如果疾病在早期阶段被发现，手术通常是治愈的。然而，大约三分之一的患者接受了旨在切除所有肾癌的手术，他们的疾病在未来会复发，这通常是无法治愈的。正因为如此，肾癌被认为是最致命的尿路癌症，高达50%的患者死于他们的疾病。癌细胞将DNA注入患者的血液中。通过对患者血液的研究和对循环中无细胞肿瘤DNA(CtDNA)的鉴定，液体活检有望为预测疾病复发和监测疾病复发提供有用的信息。这将使量身定做的干预措施能够改善患者的预后。然而，这种ctDNA只是血液循环中发现的全部游离DNA的一小部分，血液循环中也有来自体内健康细胞的游离DNA。无细胞肿瘤DNA的一小部分使这一点很难被检测到。尽管如此，对其他癌症的研究，如肺癌、乳腺癌和结肠癌，已经显示出在检测这些癌症患者血液中肿瘤特异性DNA变化方面的有希望的结果，这可能具有临床意义。不幸的是，使用同样的方法来鉴定肾细胞癌中的ctDNA更加困难和令人失望。我们自己实验室之前的工作已经显示了ccRCC中一种名为甲基化的DNA修饰的显著变化。此外，最近的小规模研究表明，当甲基化变化用于询问血液和尿液中的cfDNA时，ccRCC患者的ctDNA水平比以前报道的要高得多。因此，我们假设使用肾癌特异性甲基化变化(而不是DNA突变变化)来鉴定肾癌患者血液中的ctDNA将改善肾癌患者中ctDNA的检测。我们利用公开的数据进行了一项大规模研究，以开发ccRCC特异性甲基化的ctDNA图谱，该图谱将在我们自己队列中的肿瘤样本中得到验证。之后，我们将利用创新技术，检测患者血液或尿液中多达10000的甲基化变化，研究大量慢性肾细胞癌患者的血液，包括诊断时和整个随访过程中的血液以及健康对照组。患者会有代表肾细胞癌的疾病谱。所有样本都有高质量的、注释良好的临床数据，这些数据将与ctDNA发现相关联，以确定这一特征在预测和检测手术后疾病复发方面的效用。这可能会导致临床上适用的测试的发展，以改善患者的结果。

The number of patients diagnosed with kidney cancer (RCC) has been increasing over the last 10 years and accounts for 4% of all cancers in the UK. Clear cell RCC (ccRCC) is the predominate subtype accounting for approximately 75% of all cases. Surgery is often curative if the disease is identified at an early stage. However approximately 1/3 of patients who undergo surgery with the aim of removing all the kidney cancer, develop recurrence of their disease in the future, which is often incurable. Because of this, RCC is recognised as the most lethal cancer of the urinary tract with up to 50% of patients dying of their disease. Cancer cells shed DNA into the blood of patients with the disease. It is anticipated that liquid biopsy, through study of the patients' blood and identification of this circulating cell free tumour DNA (ctDNA) will provide useful information for predicting disease recurrence and monitoring for this disease recurrence. This would then allow tailored interventions to improve patient outcomes. However, this ctDNA is a small fraction of the overall cell free DNA found in the circulation, which also has cell free DNA derived from healthy cells within the body. The small fraction of cell-free tumour DNA makes this difficult to detect. Nonetheless, studies in other cancers, such as lung, breast and colon cancer, have shown promising results for the detection of tumour specific DNA changes in the blood of patients with those respective cancers, which could have clinically meaningful implications. Unfortunately using the same approaches to identify ctDNA in RCC has been more difficult and disappointing. Previous work in our own lab has shown significant changes in a DNA modification called methylation, in ccRCC. Furthermore, very recent small-scale studies have demonstrated much higher levels of ctDNA in ccRCC patients than previously reported, when methylation changes are used to interrogate the cfDNA in both blood and urine. We therefore hypothesis that using RCC specific methylation changes (rather than DNA mutational changes) to identify ctDNA in the blood of patients with RCC will improve the detection of ctDNA in RCC patients. We have performed a large-scale study with publicly available data to develop a ccRCC specific methylated ctDNA profile, which will be validated in tumour samples from our own cohort. Thereafter using innovative technology, that allows the detection of up to 10000 methylation changes in the blood or urine of patients, we will study the blood from a large number of patients with ccRCC both at diagnosis and throughout follow-up as well as healthy controls. Patients will have RCC representative of the spectrum of disease. All samples have high quality well annotated clinical data which will be correlated with ctDNA findings to identify the utility of this profile for predicting and detecting disease recurrence following surgery. This will potentially lead to the development of clinically applicable tests to improve patient outcomes.