Analysis of myositis autoantibodies in Chinese patients with cancer-associated myositis

Background Cancer-associated myositis (CAM) has poor prognosis and causes higher mortality. In general, myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) have been shown to be useful biomarkers for its diagnosis. Methods In the present study, focus was given in assessing the presence, prevalence, and diagnostic values of myositis autoantibodies in Chinese patients diagnosed with CAM. The sera collected from 49 CAM patients, 108 dermatomyositis/polymyositis (DM/PM) patients without cancer, 105 disease controls, and 60 healthy controls were detected for the presence of 16 autoantigens (Jo-1, OJ, EJ, PL-7, PL-12, MDA5, TIF1 gamma, Mi-2 alpha, Mi-2 beta, SAE1, NXP2, SRP, Ku, PM-Scl75, PM-Scl100, and Ro-52) using a commercial Euroline assay. Results The frequency of anti-TIF1 gamma was significantly higher in CAM patients than in DM/PM patients without cancer (46.9% vs 14.8%, P < .001). Importantly, the sensitivity and specificity for this MSA were 46.9% and 85.2%, respectively. These helped to differentiate CAM patients from DM/PM patients without cancer. However, there was no difference in other MSAs and MAAs between CAM and DM/PM patients without cancer. Conclusion The present study indicates that anti-TIF1 gamma levels can serve as important biomarkers for CAM diagnosis and help in distinguishing between CAM and DM/PM patients without cancer.