C-reactive protein kinetics as prognostic biomarkers in advanced melanoma treated with immune checkpoint inhibitors.

C-reactive protein (CRP) kinetics has emerged as a potential biomarker for predicting treatment response and survival in various tumors treated with immune checkpoint inhibitors (ICIs). However, data on CRP kinetics in melanoma are limited. This study evaluates the relationship between CRP kinetic groups and progression-free survival (PFS) and overall survival (OS) in 104 advanced melanoma patients treated with ICIs from 2015 to 2023. Patients were classified into four CRP kinetic groups: CRP flare responders, defined as patients whose CRP at least doubles within 1 month and then falls below baseline by 3 months; CRP responders, whose CRP decreases by ≥30% from baseline within 3 months without doubling; all-normal CRP, whose CRP remains below the upper limit of normal throughout the first 3 months; and CRP nonresponders, who do not meet these criteria. Amongst patients, 64.4% received anti-programmed death-1 monotherapy and 35.6% received the nivolumab-ipilimumab combination. Median PFS was 4.80 months in CRP nonresponders, 10.90 months in CRP responders, 8.83 months in CRP flare responders and 33.57 months in all-normal CRP patients (P < 0.001). Similarly, median OS was 11.9 months in CRP nonresponders, 38.1 months in CRP responders, 21.5 months in CRP flare responders and 54.5 months in all-normal CRP patients (P < 0.001). Multivariate analysis confirmed CRP kinetic groups as an independent predictor of PFS, OS and objective response. CRP kinetic classification is a simple prognostic tool for advanced melanoma patients treated with ICIs and is associated with improved survival outcomes, underscoring the clinical value of CRP monitoring.