Preexisting Autoantibodies and Immune Related Adverse Events in Metastatic Urothelial Carcinoma Patients Treated by Pembrolizumab.

INTRODUCTION: Immune checkpoint inhibitor are standard therapy in metastatic urothelial carcinoma. No predictive biomarker of immune related adverse events (iRAE) exists. Antinuclear antibodies (ANA) can be the sign of a subclinical autoimmune condition that could be enhanced by Immune checkpoint inhibitor. We decided to assess the predictive value of baseline autoantibodies and ANA for iRAE in metastatic urothelial carcinoma patients treated with pembrolizumab and explore their prognostic signification. PATIENTS AND METHOD: Data concerning patients treated in our institution between 2015 and 2020 with pembrolizumab for metastatic urothelial carcinoma with available baseline value of ANA and other autoantibodies was collected. ANA with titer >1/80 were defined positive. RESULTS: A total of 68 patients were included. Fifty-five (80%) had ANA >1/80 and among them 21 patients (30%) had ANA >1/160. Seven patients with ANA >160 (33%) presented iRAE vs. 5 patients (10%) in the rest of the population. Presence of ANA >160 was significantly associated with iRAE (P = .029) and limiting toxicity (P = .048) in univariate analysis. iRAE tend to occur earlier, before the third cycle, for patients with ANA >1/160 as compared to rest of the patients (28% vs. 6%, P = .052). Exploratory analysis did not reveal correlation between progression free survival or overall survival and ANA >1/160 in univariate or in multivariate analysis including the Bellmunt score (HR = 0.7, 95%CI [0.38-1.35], P = .5). CONCLUSION: The presence of ANA >1/160 is associated with iRAE and limiting toxicity of pembrolizumab.