Autoimmune Disease in Patients With Advanced Thymic Epithelial Tumors.

Introduction: Paraneoplastic autoimmune diseases (ADs) are a hallmark of thymic epithelial tumors (TETs) and affect treatment management in patients with advanced-stage tumors, yet the risk factors for development of AD in advanced TET remain poorly understood.

Methods: All patients with advanced TET treated at Stanford University between 2006 and 2020 were included. Charts were retrospectively reviewed for the presence of AD, demographic information, and treatment history. Next-generation sequencing was performed on available TET tissue. Multivariate regression was used to evaluate variables associated with AD.

Results: A total of 48 patients were included in the analysis with a median follow-up of 5.4 years. One-third (n = 16, 33%) were diagnosed with having ADs, with 28 distinct ADs identified. The only significant difference observed in the AD cohort compared with the non-AD cohort was a higher proportion of thymoma histotype (81% versus 47%,  = 0.013). The most common AD events were myasthenia gravis (n = 7, 44%) followed by pure red cell aplasia (n = 5, 31%). In the multivariate models, there were no independent factors associated with AD, either at TET diagnosis or subsequent to TET diagnosis. Genomic data were available on 18 patients, and there were no overlapping mutations identified in the nine patients with AD.

Conclusions: ADs are common in patients with advanced TETs. Prior total thymectomy does not affect the development of subsequent AD. Patients who developed AD other than myasthenia gravis were more likely to do so several years after TET diagnosis. Additional work, including multiomic analyses, is needed to develop predictive markers for AD in advanced TET.