TY - JOUR T1 - Pre-existing antiacetylcholine receptor autoantibodies and B cell lymphopaenia are associated with the development of myositis in patients with thymoma treated with avelumab, an immune checkpoint inhibitor targeting programmed death-ligand 1 JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 150 LP - 152 DO - 10.1136/annrheumdis-2018-213777 VL - 78 IS - 1 AU - Andrew L Mammen AU - Arun Rajan AU - Katherine Pak AU - Tanya Lehky AU - Livia Casciola-Rosen AU - Renee N Donahue AU - Lauren M Lepone AU - Anastasia Zekeridou AU - Sean J Pittock AU - Raffit Hassan AU - Jeffrey Schlom AU - James L Gulley Y1 - 2019/01/01 UR - http://ard.bmj.com/content/78/1/150.abstract N2 - Immune checkpoint inhibitors enhance the immune response against tumours but may also trigger immune-related adverse events (IRAEs). Myositis is a rare IRAE. For example, creatine kinase (CK) elevations occurred in just 0.3% of those treated with avelumab, an antiprogrammed death-ligand 1 antibody.1 Thymomas are the most common anterior mediastinal masses in adults. Since effective systemic therapies for thymic epithelial tumours are lacking, we included seven patients with recurrent thymoma and one patient with recurrent thymic carcinoma in a phase I trial of avelumab (NCT01772004). Details regarding this trial have been published separately.2 Myasthenia gravis and myositis occur in up to 30% and 5% of patients with thymoma, respectively.3 Although no patient had a history of autoimmunity or weakness and each had normal baseline CK levels, four patients developed weakness and elevated CK levels, ranging from 762 IU/L to 16 037 IU/L, within 5 weeks of avelumab administration (see online supplementary text and table 1). CK levels normalised in patients within weeks of stopping avelumab and starting immunosuppressive therapy. Of note, … ER -