类风湿性关节炎（RA）患者中，有些患者对英夫利昔单抗（IFX）出现次级无反应。尽管治疗药物监测（TDM）是优化IFX治疗的有用工具，但目前尚不清楚它是否能帮助识别次级无反应的风险。本研究旨在探讨血清IFX或其他生物标志物水平是否能预测因次级无反应而中断IFX的可行性。使用京都大学类风湿性关节炎管理联盟队列数据库，进行了一项单中心回顾性研究，时间范围为2011年至2020年。采用液相色谱串联质谱法测定血清IFX水平，采用电化学发光法定量血清肿瘤坏死因子-α和白细胞介素-6水平，并检测抗药物抗体。共有310名患者中纳入84名患者进行了分析。通过接收者操作特征分析确定了生物标志物的截断水平。使用IFX水平、肿瘤坏死因子-α水平、白细胞介素-6水平和抗药物抗体阳性进行分层分组，IFX的持续性在各组之间相似。IFX水平较低且白细胞介素-6水平较高的组有最差的治疗持续性（p = 0.017）和最频繁的疾病恶化（90.0%，p < 0.001）。通过评估白细胞介素-6和IFX水平，而不仅仅是IFX水平，我们能够确定处于中断IFX治疗风险中的患者。这些发现支持了测量IFX和白细胞介素-6水平用于成功维持RA治疗的可行性。

Secondary non-response to infliximab (IFX) occurs in some patients with rheumatoid arthritis (RA). Although therapeutic drug monitoring (TDM) is a useful tool to optimize IFX therapy, it is unclear whether it can help to identify the risk of secondary non-response. This study aimed to explore the utility of serum levels of IFX or other biomarkers to predict IFX discontinuation owing to secondary non-response. A single-center, retrospective study was conducted using the Kyoto University Rheumatoid Arthritis Management Alliance cohort database between 2011 and 2020. Serum IFX levels were measured using liquid chromatography-tandem mass spectrometry. An electrochemiluminescence assay was used to quantify serum levels of tumor necrosis factor-α and interleukin-6 and detect anti-drug antibodies. Eighty-four out of 310 patients were eligible for this study. The cutoff levels of biomarkers were determined by receiver operating characteristic analysis. IFX persistence was similar between groups stratified using IFX levels, tumor necrosis factor-α levels, interleukin-6 levels, and anti-drug antibodies positivity. The group with lower IFX and higher interleukin-6 levels had the worst therapy persistence (p = 0.017) and the most frequent disease worsening (90.0%, p < 0.001). Evaluating both interleukin-6 and IFX levels, not just IFX alone, enabled us to identify patients at risk of discontinuing IFX treatment. These findings support the utility of measuring IFX and interleukin-6 levels for successful maintenance therapy for RA.