The role of liquid biopsy in identifying circulating molecular predictors of response or resistance to systemic therapy in hepatocellular carcinoma

尽管最近关于肝细胞癌的分子知识和许多新的系统治疗方案具有优势，但预后仍然令人沮丧。具体地说，可药物改变很少，也没有可用的生物标记物来预测对许多可用的全身药物的反应或耐药性(除了Ramucirumab的血清甲胎蛋白(AFP))。我们对晚期肝癌患者进行了液体活检研究，发现晚期肝癌患者循环肿瘤DNA(CtDNA)的突变谱与早期切除患者组织中的突变谱相似。我们的初步结果表明，PI3K-MTOR通路突变的患者对索拉非尼存在主要耐药，导致较短的无进展生存期。另一项研究表明，Wnt通路激活与体内对PD-1抑制剂的耐药性有关。因此，我们假设，在ctDNA中检测特定的通路改变，例如在PI3K-MTOR通路或Wnt/β-catenin通路中，能够分别预测对酪氨酸激酶或检查点抑制剂的耐药性。最终，这项翻译研究项目旨在通过建立液体活检在肝细胞癌患者临床治疗中的作用来改善肝细胞癌治疗和疾病监测的核心问题，特别是通过将来自循环肿瘤DNA(CtDNA)的连续采样的分子结果与患者的临床终点相结合。具体地说，我们将使用最先进的液体活检技术来解决肝细胞癌临床治疗中的两个关键问题：如何识别对系统治疗有反应或抵制的患者，以及什么是原始和获得性耐药的驱动因素。该项目的成功实施将产生一套全面的液体活组织检查生物标记物，用于在前瞻性登记临床试验中进行测试，以预测对系统治疗的反应。该项目有可能重新定义指导肝癌决策的模型，特别是在系统治疗分配方面，目前系统治疗依赖于横断面成像和血清AFP水平，缺乏有效治疗分配的分子生物标志物。此外，该项目将在耐药时提供新的分子发现，这对未来治疗方法的发展是有用的。与传统的组织活检相比，使用液体活检来解决这些问题的明显优势是多方面的(微创采血、顺序应用和纵向采样、捕获肿瘤异质性)。这促进了基于生物标记物的临床试验的实施，并克服了晚期患者有限的组织可获得性，这显然是肝细胞癌研究中尚未满足的需求。克服肿瘤异质性对于肿瘤负荷大、多发结节和转移扩散的晚期患者尤为重要。

Despite recent advantages regarding molecular knowledge of HCC and many novel systemic treatment options, the prognosis remains dismal. Specifically, druggable alterations are scarce and there are no biomarkers available to predict responsiveness or resistance to the many available systemic drugs (except serum alpha-fetoprotein (AFP) for ramucirumab). We have conducted a liquid biopsy study on patients with advanced HCC found that the mutation profile in circulating tumor DNA (ctDNA) of advanced HCC patients is similar to that in tissue of early stage patients undergoing resection. Our preliminary results suggest a primary resistance to sorafenib in patients with mutations in the PI3K-MTOR pathway resulting in shorter progression-free survival. Another study has suggested an association between Wnt pathway activation and resistance to PD-1 inhibitors in vivo. Therefore, we hypothesize that detection of specific pathway alterations, e.g. in the PI3K-MTOR pathway or Wnt/beta-catenin pathway, in ctDNA is capable to predict resistance to tyrosine kinase or checkpoint inhibitors, respectively.Ultimately, this translational research project aims to improve core problems in HCC management and disease monitoring by establishing the role of liquid biopsy in the clinical management of HCC patients, specifically by incorporating molecular findings derived from sequential sampling of circulating tumor DNA (ctDNA) with clinical endpoints of patients. Specifically, we will use state-of-the-art liquid biopsy technologies to tackle two crucial questions in the clinical management of HCC: How can patients who respond to or resist systemic therapies be identified and what are the drivers of primary and acquired resistance. The successful execution of this project will yield a comprehensive set of liquid biopsy biomarkers to be tested in prospective registration clinical trials for the prediction of response to systemic therapy. The project has the potential to redefine the model that guides decision-making in HCC, particularly in the area of allocation to systemic therapies, which currently relies on cross-sectional imaging and serum levels of AFP and lacks molecular biomarkers for effective treatment allocation. Furthermore, this project will provide novel molecular findings at the time of resistance that are useful for the development of future therapeutic approaches. The obvious advantage of using liquid biopsy over conventional tissue biopsies to address these questions are manifold (minimally invasive blood draw, sequential applications and longitudinal sampling, capture of tumor heterogeneity). This facilitates the implementation of biomarker-based clinical trials and overcome limited accessibility to tissue of advanced patients, a clear unmet need in HCC research. Overcoming tumor heterogeneity is of particular interest in advanced stages with large tumor burden, multiple nodules and metastatic spread.