CRP kinetics to predict long-term efficacy of first-line immune-checkpoint inhibition combination therapies in metastatic renal cell carcinoma: An updated multicenter real-world experience applying different CRP kinetics definitions.

Abstract

405 Background: Although biomarkers predicting therapy response in 1st line metastatic renal carcinoma (mRCC) therapy remain to be defined, C-reactive protein (CRP) kinetics have recently been associated with immunotherapy (IO) response. To assess the predictive and prognostic power of two contemporary CRP kinetics definitions in a large, real-world 1st line mRCC cohort. Methods: mRCC patients treated with IO-based 1st line therapy within 5 years were retrospectively included in this multi-center study. According to Fukuda et al., patients were defined as ‘CRP flare-responder’, ’CRP responder’ and ‘non-CRP responder’; according to Ishihara et al., as ‘normal’, ‘normalized’ and ‘non-normalized’ based on their early CRP kinetics. Patient and tumor characteristics were compared, and treatment outcome was measured by overall (OS) and progression-free survival (PFS), including multivariable Cox regression analyses. Results: Out of 316 mRCC patients, 227 (72%) were assigned to CRP groups according to Fukuda. Both CRP flare- (HR [Hazard ratio]: 0.59) and CRP responders (HR: 0.52) had a longer PFS, but not OS, than non-CRP responders. According to Ishihara, 276 (87%) patients were assigned to the respective groups, and both normal and normalized patients had a significantly longer PFS and OS, compared to non-normalized group. Conclusions: Different early CRP kinetics may predict therapy response in 1st line mRCC therapy in a large real-world cohort. However, further research regarding the optimal timing and frequency of measurement is needed.