目的：探讨仑卡奈单抗（lecanemab）在早发型阿尔茨海默病（early onset Alzheimer’s disease，EOAD）患者中的临床疗效及安全性，为疾病修饰治疗（disease modification therapy，DMT）的临床应用提供参考。

方法：报告 1 例 54 岁男性 EOAD 患者的诊疗过程，结合临床表现、影像学特征、治疗反应以 及相关文献，分析仑卡奈单抗的疾病修饰作用。

结果：患者在接受传统抗痴呆药物治疗基础上，启动仑卡奈单抗（静脉注射10 mg/kg体质量， 1次/2周）治疗，并且随访 9 个月。患者治疗前的简易智力状态检查（Mini-mental State Examination，MMSE）量 表 评 分 为 20 分 ，蒙 特 利 尔 认 知 评 估（Montreal Cognitive Assessment，MoCA）量表评分为12分，β-淀粉样蛋白（amyloid β-protein，Aβ）-PET显示标 准化摄取值比（standardized uptake value ratio，SUVR）为 1.325（阳性），Centiloid 值为 51.073。治疗后 9 个月，Aβ-PET 显示 SUVR 降至 1.015（阴性阈值为 1.100），Centiloid 值降 低55.688；Tau-PET显示病理沉积未进一步进展。临床量表评估显示MMSE量表评分提高 1分（达到21分），MoCA量表和波士顿命名测试（Boston Naming Test，BNT）量表评分维持 稳定。治疗期间，患者未发生脑微出血和脑水肿等不良反应。

结论：本病例报告显示，仑卡奈单抗可有效清除脑内 Aβ 沉积，延缓 Tau 病理进展，改善 EOAD患者的功能，并且安全性良好。该病例为EOAD的早期DMT干预提供了临床证据。

Objective: To investigate the clinical effectiveness and safety of lecanemab in patients with early-onset Alzheimer's disease (EOAD), thereby providing a reference for the clinical application of disease-modifying treatment (DMT).

Methods: The diagnosis and treatment process of a 54-year-old male patient with EOAD were reported, and the disease modifying effect of lecanemab was analyzed based on clinical manifestations, imaging features, treatment response and relevant literature.

Results: After receiving traditional anti-dementia drug treatment, the patient initiated treatment with lecanemab (10 mg/kg body weight, once every 2 weeks) and was followed up for 9 months. Before treatment, the Mini-mental State Examination (MMSE) scale score was 20, Montreal Cognitive Assessment (MoCA) scale score was 12, amyloid β-protein (Aβ)- PET showed a standardized uptake value ratio (SUVR) of 1.325 (positive), and the Centiloid value was 51.073. After 9 months of treatment, β -PET indicated a reduction in SUVR to 1.015 (below the negative threshold of 1.10) and a decrease of 55.688 units in Centiloid value; Tau-PET showed no further progression of pathological deposits. Clinical assessments revealed improvement of 1 point in MMSE score (to 21 points), and stable scores in MoCA and Boston Naming Test (BNT). No adverse effects, such as cerebral microhemorrhages or edema, were observed during treatment.

Conclusion: This case report shows that lecanemab can effectively clear the deposition of Aβ in the brain, delay the pathological progression of Tau protein, improve the function in the patient with EOAD, and has good safety. This case provides clinical evidence for early DMT intervention in EOAD.