Increased levels of IL-6, BCA and BAFF were significantly negatively associated with survival (IL-6: HR=4.41, 95%CI: 1.26-15.43, p=0.0112; BCA: HR=4.74, 95%CI: 1.35-16.64, p=0.0076, and BAFF: HR=4.39, 95%CI:1.26-15.32, p=0.0114)...Higher baseline plasma levels of IL-6, BCA and BAFF were significantly associated with worse survival outcomes in mRCC pts treated with nivolumab within an exploratory cohort of NIVOREN trial.