To identify novel predictive biomarkers, we explored the characteristics of blood-circulating immune cell subsets within the population of the TITAN-RCC trial (NCT02917772)....Higher percentages of blood-circulating 4-1BB+ CD4+ T cells (adjusted odds ratio (ORadj) 1.05, 95% CI 1.02-1.08), 4-1BB+ CD8+ T cells (ORadj 1.03, 95% CI 1.01-1.07) and LAG3+ CD4+ T cells (ORadj 1.03, 95% CI 1.01-1.05) were found in responders to nivo induction compared to non-responders.