Table3_Application of circulating tumour DNA in terms of prognosis prediction in Chinese follicular lymphoma patients.XLSX

Background: Follicular lymphoma (FL), an indolent non-Hodgkin lymphoma (NHL), is generally incurable. Favourable prognosis and durable remission are crucial for FL patients. The genetic mutation spectrum provides novel biomarkers for determining the prognosis of FL patients, but its detection is easily affected by the collection of tumour tissue biopsies. In this study, we aimed to describe the mutational landscape of FL using circulating tumour DNA (ctDNA) samples and to explore the relationship between mutations and prognostic indicators of clinical outcome in patients with newly diagnosed follicular lymphoma and the prognostic value of such mutations.
Methods: A total of 28 patients with newly diagnosed FL were included in this study. A targeted NGS-based 59-gene panel was used to assess the ctDNA mutation profiles. Differences in clinical factors between patients carrying mutations and those without mutations were analysed. We also explored the relationship between gene mutation status, mean VAFs (variant allele frequencies) and clinical factors. The Kaplan‒Meier method was applied to analyse the overall survival (OS) and progression-free survival (PFS) of patients carrying mutations and those without mutations.
Results: ctDNA mutations were detectable in 21 (75%) patients. The most commonly mutated genes were CREBBP (54%, 15/28), KMT2D (50%, 14/28), STAT6 (29%, 8/28), CARD11 (18%, 5/28), PCLO (14%, 4/28), EP300 (14%, 4/28), BCL2 (11%, 3/28), and TNFAIP3 (11%, 3/28), with a mutation frequency of >10%. Patients with detectable ctDNA mutation tended to present with advanced Ann Arbor stage (III-IV) (p = 0.009), high FLIPI risk (3–5) (p = 0.023) and severe lymph node involvement (No. of involved areas ≥5) (p = 0.02). In addition, we found that the mean VAF was significantly higher in patients with advanced Ann Arbor stage, high-risk FLIPI, elevated lactate dehydrogenase (LDH: 0–248U/L), advanced pathology grade, bone marrow involvement (BMI) and lymph node involvement. Additionally, KMT2D, EP300, and STAT6 mutations were associated with inferior PFS (p < 0.05).
Conclusion: We described the ctDNA mutation landscapes in Chinese patients with newly diagnosed FL and found that ctDNA VAF means reflect tumour burden. Moreover, PFS was shorter in patients with KMT2D, EP300 and STAT6 mutations.

背景：滤泡性淋巴瘤（Follicular lymphoma, FL）是一种惰性非霍奇金淋巴瘤（non-Hodgkin lymphoma, NHL），目前通常难以治愈。对于FL患者而言，获得良好预后与持久缓解至关重要。遗传突变谱可为FL患者的预后判断提供新型生物标志物，但此类突变的检测极易受肿瘤组织活检样本采集环节的影响。本研究旨在利用循环肿瘤DNA（circulating tumour DNA, ctDNA）样本描绘FL的突变图谱，并探讨初诊滤泡性淋巴瘤患者的基因突变与临床预后指标之间的关联，以及此类突变的预后价值。
方法：本研究共纳入28例初诊FL患者。采用基于靶向二代测序（next-generation sequencing, NGS）的59基因检测panel，对ctDNA突变谱进行分析。对比分析携带突变与未携带突变患者的临床因素差异，同时探究基因突变状态、平均变异等位基因频率（variant allele frequencies, VAF）与临床因素之间的关联。采用Kaplan-Meier法分析携带突变与未携带突变患者的总生存期（overall survival, OS）与无进展生存期（progression-free survival, PFS）。
结果：21例（75%）患者可检测到ctDNA突变。突变频率超过10%的高频突变基因依次为CREBBP（54%，15/28）、KMT2D（50%，14/28）、STAT6（29%，8/28）、CARD11（18%，5/28）、PCLO（14%，4/28）、EP300（14%，4/28）、BCL2（11%，3/28）与TNFAIP3（11%，3/28）。携带可检测ctDNA突变的患者更易表现为Ann Arbor分期Ⅲ~Ⅳ期（p=0.009）、高FLIPI风险（3~5分，p=0.023）以及严重淋巴结受累（受累区域数≥5，p=0.02）。此外，本研究发现，Ann Arbor分期晚期、高FLIPI风险、乳酸脱氢酶（lactate dehydrogenase, LDH）升高（参考值0~248U/L）、病理分级晚期、骨髓受累（bone marrow involvement, BMI）及淋巴结受累患者的平均VAF显著升高。同时，KMT2D、EP300与STAT6突变与较差的无进展生存期相关（p<0.05）。
结论：本研究描绘了中国初诊FL患者的ctDNA突变图谱，并发现ctDNA平均VAF可反映肿瘤负荷。此外，携带KMT2D、EP300及STAT6突变的患者无进展生存期更短。