FRI0329 ANALYSIS OF 11 CASES OF ANTI-PL-7 ANTIBODY POSITIVE PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES. MALIGNANCY MAY NOT BE UNCOMMON COMPLICATION IN ANTI-PL-7 ANTIBODY POSITIVE MYOSITIS PATIENTS
Authors: Taiga Kuga, Yoshiyuki Abe, Masakazu Matsushita, Kurisu Tada, Ken Yamaji, Naoto Tamura
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Various autoantibodies are known to be related to idiopathic inflammatory myopathies (IIM). Anti-PL-7 antibody is anti-threonyl-tRNA synthetase antibody associated with antisynthetase syndrome (ASS). Since anti-PL-7 antibody is rare (mostly 1-4% of myositis, while a Japanese study reported 17%), little is known as to clinical characteristics of it (1). <h3>Objectives</h3> To analyze clinical characteristics of anti-PL-7 positive IIM patients. <h3>Methods</h3> Anti-PL-7 antibody was detected by EUROLINE Myositis Profile 3. IIM diagnosis was made by the 2017 EULAR/ACR classification criteria (2) and/or Bohan And Peter classification (3). Eleven anti-PL-7 antibody positive adult patients (all female), age at onset (61.5±12.6 years) were enrolled in this study between 2009 and 2018. Clinical manifestations, laboratory and instrumental data were reviewed in this single centre retrospective cohort. <h3>Results</h3> Characteristic symptoms were identified at diagnosis: skin manifestations (7/11 cases, 63.6%), muscle weakness (8/11 cases, 72.7%), arthralgia (5/11 cases, 45.5%) and Raynaud's phenomenon (4/11 cases, 36.4%). Myogenic enzymes were elevated in most cases (10/11 cases, 90.9%). ILD was detected in all patients (11/11 cases, 100%) and 2 patients (18.2%) developed rapidly progressive ILD. Largest IIM subtype was polymyositis (PM, 5/11 cases), followed by dermatomyositis (DM, 3/11 cases) and amyopathic dermatomyositis (ADM, 3/11 cases). Five patients (45.5%) complicated with malignancy within 3 years from the diagnosis of IIM. Though clinical manifestations and laboratory data showed any difference between malignancy group and non-malignancy group, all 3 ADM cases but no DM cases complicated with malignancy in this study. <h3>Conclusion</h3> Anti-PL-7 antibody positive IIM patients frequently complicated with ILD. Frequency of cancer in ASS patients within three years from diagnosis was 1.7% and not much different from the general population in previous report from France (4). Though this study only included IIM patients and may have selection bias, careful malignancy survey may be essential in Anti-PL-7 antibody positive IIM patients. <h3>References</h3> [1] Y Yamazaki, et al. Unusually High Frequency of Autoantibodies to PL-7 Associated With Milder Muscle Disease in Japanese Patients With Polymyositis/DermatomyositisARTHRITIS &amp; RHEUMATISM Vol. 54, No. 6, June 2006, pp 2004–2009 [2] Lundberg IE, Tjärnlund A, Bottai M, et al. EULAR/ACR classification criteria for adult and juvenile idiopathic inflammatory myopathies and their Major Subgroups. Ann Rheum Dis. 2017;76:1955–64. [3] Bohan A, Peter J. Polymyositis and dermatomyositis. N Engl J Med 1975, 292: 344-347; 403-407. [4] Hervier B, et al. Hierarchical cluster and survival analyses of antisynthetase syndrome: phenotype and outcome are correlated with anti-tRNA synthetase antibody specificity. Autoimmunity reviews. 2012; 12:210–217. <h3>Disclosure of Interests</h3> Taiga Kuga: None declared, Yoshiyuki Abe: None declared, Masakazu Matsushita: None declared, Kurisu Tada Grant/research support from: Eli Lilly, Ken Yamaji: None declared, Naoto Tamura Grant/research support from: Astellas Pharma Inc., Asahi Kasei Pharma, AYUMI Pharmaceutical Co., Chugai Pharmaceutical Co. LTD, Eisai Inc., :Takeda Pharmaceutical Company Ltd., Speakers bureau: Janssen Pharmaceutical K.K., Bristol-Myers Squibb K.K., :Mitsubishi Tanabe Pharma Co.