The role of circulating tumor DNA from cerebrospinal fluid as a minimal-invasive biomarker for comprehensive genetic profiling and improved outcome prediction in patients with CNS lymphoma

原发性中枢神经系统淋巴瘤(PCNSL)是一种异质性脑癌。PCNSL临床结果背后的遗传因素尚不清楚。从侵入性立体定向活检或脑外科手术中获得的肿瘤材料的基因分型往往由于样本量小或组织靶向不准确而不充分。此外，这些手术会导致一部分患者的术中和术后并发症，包括颅内出血和严重感染。循环肿瘤DNA(CtDNA)是一种新兴的跨肿瘤学的生物标志物，包括淋巴瘤。我们已经成功地将定向捕获下一代测序(NGS)方法(CAPP-SEQ，通过深度测序进行癌症个性化分析)转移到我们的机构，使其能够对淋巴瘤患者的ctDNA进行超灵敏和全面的分析。我们优化了CAPP-Seq用于PCNSL，并证明在血浆和脑脊液(CSF)中很容易检测到ctDNA。此外，脑脊液中的ctDNA似乎准确地反映了PCNSL肿瘤的突变情况和基因组成(n=4)。在这项拟议的研究中，我们的目标是利用一项前瞻性多中心试验(n=84，DRKS00005503)中可用的诊断脑脊液来建立脑脊液ctDNA作为一种无需活检的生物标记物，用于全面的肿瘤基因分型、肿瘤负荷评估、PCNSL突变情况的特征以及PCNSL结果的预测。我们将进一步利用来自脑脊液ctDNA基因分型的信息以及传统的临床和放射学风险因素来开发一种新的综合风险模型，该模型可以比单因素传统模型更准确和更好地预测结果。如果成功，我们设想脑脊液测序将作为一种微创方法，在不需要侵入性手术或足够数量的肿瘤DNA的情况下，全面评估PCNSL基因型别。此外，一种改进的、个性化的结果预测综合算法可能会显著加强PCNSL患者的临床管理，并有助于指导未来的治疗。

Primary central nervous system lymphoma (PCNSL) represents a heterogeneous brain cancer type. Genetic factors underlying PCNSL clinical outcomes are poorly understood. Genotyping from tumor material achieved from invasive stereotactic biopsies or brain surgery is often insufficient due to small sample size or inaccurate tissue targeting. Moreover, these procedures cause intra- and postsurgical complications in a subset of patients, including intracranial hemorrhage and severe infections. Circulating tumor DNA (ctDNA) is an emerging biomarker across oncology, including lymphomas. We have successfully transferred a targeted capture next-generation sequencing (NGS) approach (CAPP-Seq, Cancer Personalized Profiling by Deep Sequencing) to our institution that allows ultrasensitive and comprehensive profiling of ctDNA in lymphoma patients. We optimized CAPP-Seq for its use in PCNSL and demonstrated that ctDNA is readily detectable in blood plasma and cerebrospinal fluid (CSF). Moreover, ctDNA from CSF accurately seems to mirror the mutational landscape and genetic composition of PCNSL tumors (n=4). In the proposed study, we aim to utilize available diagnostic CSF from a prospective multi-center trial (n=84, DRKS00005503) to establish CSF ctDNA as a biopsy-free biomarker for comprehensive tumor genotyping, assessment of tumor burden, characterization of PCNSL mutation landscapes, and prediction of PCNSL outcomes. We will further utilize information from CSF ctDNA genotyping together with conventional clinical and radiographic risk factors to develop a novel integrative risk models that allows accurate and improved outcome prediction over single-factor traditional models. If successfull, we envision a role of CSF sequencing as a minimal-invasive way to comprehensively assess PCNSL genotypes without the need for invasive surgical procedures or sufficient amounts of tumor DNA. Moreover, an improved and personalized integrative algorithm for outcome prediction might significantly enhance clinical management of patients with PCNSL with and help guide therapies in the future.