Background There are increasing reports of myasthenia gravis (MG) following oncological treatment with immune checkpoint inhibitors (ICIs). Methods and results A 66-year-old man with stage 3A lung adenocarcinoma was treated with second weekly infusions of durvalumab, a programmed cell death ligand-1 inhibitor, at a dose of 10 mg/kg. After the fourth infusion, he developed diplopia, dyspnoea and constitutional symptoms including headache, weakness and anorexia. 1 month later, he developed dysphagia and dysphonia. Examination showed proximal limb weakness with fatigability. An ice pack test was positive. Blood tests revealed a raised creatine kinase and positive PM-Scl75 antibody. Antititin antibody was strongly positive in the serum and cerebrospinal fluid. Antibodies for acetylcholinesterase receptor and antimuscle-specific kinase were negative. Electromyography showed myopathic changes. The patient was treated with steroids, pyridostigmine, mycophenolate mofetil and intravenous immunoglobulin. Eight weeks after treatment initiation ptosis, eye movements and limb strength were markedly improved and repeat creatine kinase was normal. Conclusion Clinicians using ICIs should have a high index of suspicion for ICI-induced MG and concurrent myositis as disease can be severe and is associated with high mortality rates.

中文翻译：

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PD-L1检查点抑制剂治疗非小细胞肺癌后重症肌无力和并发肌炎

背景 越来越多的关于用免疫检查点抑制剂 (ICIs) 进行肿瘤治疗后出现重症肌无力 (MG) 的报道。方法和结果 一名患有 3A 期肺腺癌的 66 岁男性接受了第二周输注 durvalumab（一种程序性细胞死亡配体-1 抑制剂）治疗，剂量为 10 mg/kg。在第四次输注后，他出现复视、呼吸困难和全身症状，包括头痛、虚弱和厌食。1个月后，他出现吞咽困难和发音困难。检查显示肢体近端无力伴易疲劳。冰袋试验呈阳性。验血显示肌酸激酶升高和 PM-Scl75 抗体阳性。血清和脑脊液中的抗肌动蛋白抗体呈强阳性。乙酰胆碱酯酶受体抗体和抗肌肉特异性激酶抗体均为阴性。肌电图显示肌病改变。患者接受类固醇、吡啶斯的明、霉酚酸酯和静脉注射免疫球蛋白治疗。治疗开始八周后，上睑下垂，眼球运动和肢体力量明显改善，重复肌酸激酶正常。结论 使用 ICI 的临床医生应高度怀疑 ICI 引起的 MG 和并发肌炎，因为疾病可能很严重并且与高死亡率相关。